EPA-600/3-77-086
    1977                                         Ecological Research Series
                                                       ENVIRONMENTAL
                                                         PROTECTION
                                                          AGENCY

                                                        DALLAS. TEXAS
                             NORTH  AMERICAN PROJECT  •
                          A  Study  of  U.S.  Water Bodies
                                            Environmental Research Laboratory
                                           Office of Research and Development
                                          U.S. Environmental Protection Agency
                                                   Corvallis, Oregon  97330

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                RESEARCH REPORTING SERIES

Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series  These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology  Elimination of traditional grouping was  consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are

      1   Environmental  Health Effects Research
      2   Environmental  Protection Technology
      3   Ecological Research
      4   Environmental  Monitoring
      5   Socioeconomic Environmental Studies
      6   Scientific and Technical Assessment Reports (STAR)
      7   Interagency Energy-Environment Research and Development
      8   "Special" Reports
      9   Miscellaneous Reports

This report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal spe-
cies, and materials. Problems  are assessed for their long- and short-term influ-
ences. Investigations include formation, transport, and pathway studies to deter-
mine the fate of pollutants and their effects. This work provides the technical basis
for setting standards to minimize undesirable changes in living organisms in the
aquatic, terrestrial, and atmospheric environments
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.

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                                                    EPA-600/3-77-086
                                                    July  1977
       NORTH AMERICAN PROJECT — A STUDY OF U.S. WATER BODIES

A Report for the Organization for Economic Cooperation and Development



                            compiled by
                    Les Seyb and Karen Randolph
             Environmental Research Laboratory-Corvallis
                       Con/all is, Oregon  97330
            ENVIRONMENTAL RESEARCH LABORATORY-CORVALLIS
                OFFICE OF RESEARCH AND DEVELOPMENT
               U.S.  ENVIRONMENTAL PROTECTION AGENCY
                      CORVALLIS, OREGON  97330

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                                 DISCLAIMER
     This report has been reviewed by the Corvallis Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publica-
tion.  Approval  does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial  products constitute endorsement or
recommendation for use.
                                    ii

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                                   PREFACE


     The Organization for Economic Cooperation and Development, an independent
international organization for promotion of economic development in member
countries, is concerned with both the qualitative and quantitative aspects of
economic growth.  The Environment Committee of OECD is assisted by a number of
delegate groups concerned with policy development in specific sectors of the
overall environmental problem.  One of these groups is the Water Management
Sector Group, which in 1971  established a Steering Group on Eutrophication
Control to develop a series  of cooperative projects for monitoring eutrophica-
tion in inland waters.  The  overall objective of these projects was the achieve-
ment of comparability on nutrient budgets, chemical balances, and biological
productivity in water bodies.

     A regional approach was utilized to develop four project groups designed
to collect comparable data for developing evidence on the degree and extent to
which nutrient loading is correctable with the eutrophic state, and to meas-
ure the rate at which eutrophication is developing.  The projects and partici-
pating countries were:

     Nordic Project           Denmark, Finland, Norway, Sweden

     Alpine Project           Austria, France, Germany, Italy, Switzerland

     North American Project    Canada, United States

     Reservoir and Shallow    Belgium, Germany, Netherlands, Spain, United
        Lakes Project         Kingdom, United States

Dr. Richard Vollenweider of the Canada Center for Inland Waters was designated
Director of the North American Project, with Dr. Norbert Jaworski of the U.S.
Environmental Protection Agency the United States representative.  The specific
objectives of the North American Project are:

     Develop detailed nutrient (phosphorus and nitrogen) budgets for a given
     selected number of water bodies,

     Assess the chemical, physical, and biological characteristics of these
     water bodies,

     Relate the trophic state of the water body to the nutrient budgets and to
     limnological and environmental factors, and

     Synthesize, based on data from all projects, an optimal strategy for
     controlling the rate of eutrophication.

     In the United States, twenty-two water bodies were included in the pro-
gram.  Final reports on the limnology of each, emphasizing the objective of
the Project, have been compiled by the United States investigators and are con-
tained in this publication.   A synthesis based on the combined data from these
reports, and representing the fourth specific objective, will be published
subsequently.
                                      tit

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                                   CONTENTS


PREFACE                                                                    iii

LIST OF AUTHORS                                                            vii

SECTIONS

   I. FLORIDA

      Analysis of Trophic Conditions and Eutrophication
      Factors in Lake Weir, Florida                                          1

  II. MINNESOTA

      An Overview of Limnological  Characteristics
      of Shagawa Lake, Minnesota                                            25

      Lake Sal lie, Minnesota                                                47

      Three Oligotrophic Lakes  in  Northern Minnesota                         64

      Phytoplankton, Phosphorus and Sewage Effluents
      in Lake Minnetonka                                                    91

      Report on the Minneapolis City Lakes                                  117

 III. NEW YORK

      A Description of the Trophic Status and  Nutrient
      Loading for Lake George,  New York                                    135

      The Limnology of Cayuga Lake, New York - A  Summary                   182

      Trophic Status and Nutrient  Balance for  Canadarago Lake              205

  IV. OHIO

      Limnological and Geochemical Characteristics
      of the Twin Lakes Watershed, Ohio                                    242

   V. OREGON

      Waldo Lake, Oregon                                                   271

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  VI. WASHINGTON
      Lake Washington                                                      288
      Nutrient Loading and Trophic State of
      Lake Sammamish, Washington                                           301
 VII. WISCONSIN
      Lake Mendota--Nutrient Loads and Biological  Response                 321
      Report on Nutrient Load--Eutrophication Response
      of Lake Wingra, Wisconsin                                            337
      Report on Nutrient Load--Eutrophication Response
      of Selected South-Central Wisconsin Impoundments                     373
VIII. MULTIPLE-STATE LAKES AND SPECIAL TOPICS
      Limnological Characteristics of the Potomac  Estuary
      (Maryland-Virginia)                                                  402
      The John H. Kerr Reservoir (Virginia-North Carolina)                 426
      Trophic Status and Nutrient Loading for Lake Tahoe
      (California-Nevada)                                                  465
      Report on Nutrient Load--Eutrophication Response
      for the Open Waters of Lake Michigan
      (Michigan-Indiana-Illinois-Wisconsin)                                481
      Trophic Status and Nutrient Loading for Lake Michigan                499
                                      VI

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                               LIST OF AUTHORS
Susan P. Allen, Environmental Health Center, Division of Laboratories and
   Research, New York State Department of Health, Albany, NY 12201

Patrick L. Brezonik, Department of Environmental Engineering Sciences,
   University of Florida, Gainesville, FL 32601

Nicholas L. Clesceri, Rensselaer Fresh Water Institute at Lake George,
   Rensselaer Polytechnic Institute, Troy, NY 12181

G. Dennis Cooke, Center for Urban Regionalism and Environmental  Systems,
   Kent State University, Kent, OH 44240

W. T. Edmondson, Department of Zoology, University of Washington,
   Seattle, WA 98105

James J. Ferris, Rensselaer Fresh Water Institute at Lake George,
   Rensselaer Polytechnic Institute, Troy, NY 12181

G. Wolfgang Funs, Environmental Health Center,  Division of Laboratories and
   Research, New York State Department of Health, Albany, NY 12201

Charles R. Goldman, Division of Environmental Studies, University of
   California, Davis, CA 95616

Thomas E. Harr, Environmental  Quality Research  Unit, New York State
   Department of Environmental Conservation, Albany, NY 12233

Robert T. Heath, Kent State University, Kent, OH 44240

Leo J. Hetling, Environmental  Quality Research  Unit, New York State
   Department of Environmental Conservation, Albany, NY 12233

Norbert Al Jaworski, I.E.R.L., U.S.  Environmental Protection Agency,
   Research Triangle Park, NC 27711

D. Phillips Larsen, Corvallis Environmental  Research Laboratory,
   U.S. Environmental Protection Agency, Corvallis, OR 97330

G. Fred Lee, Institute for Environmental Sciences, University of Texas
   at Dallas, Richardson, TX 75080

Jose M. Lopez, Institute for Environmental Sciences, University of Texas
   at Dallas, Richardson, TX 75080
                                     vu

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Kenneth W.  Malueg, Corvallis Environmental  Research Laboratory,
   U.S. Environmental  Protection Agency, Corvallis, OR 97330

Murray R.  McComas, Kent State University, Kent, OH 44240

Robert 0.  Megard, Department of Ecology and Behavioral Biology, University
   of Minnesota, St. "Paul, MN 55108

J. J. Messer, Department of Environmental Engineering Sciences, University
   of Florida, Gainesville, FL 32601

Julie H. Moore, Department of Environmental Sciences and Engineering,
   School  of Public Health, University of North Carolina, Chapel Hill, NC 27514

Joe K. Neel, Department of Biology, University of North Dakota, Grand
   Forks,  ND 58202

Ray T. Oglesby, Department of Natural  Resources, New York State College of
   Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853

M. D. Piwoni, Institute for Environmental Sciences, University of Texas
   at Dallas, Richardson, TX 75080

Charles F.  Powers, Corvallis Environmental  Research Laboratory, U.S.
   Environmental Protection Agency, Corvallis, OR 97330

Walter Rast, Institute for Environmental Sciences, University of Texas
   at Dallas, Richardson, TX 75080

C. A. Rock, Department of Civil Engineering, University of Washington,
   Seattle, WA 98105

William D.  Sanville, Corvallis Environmental Research Laboratory, U.S.
   Environmental Protection Agency, Corvallis, OR 97330

Claire L.  Schelske, Great Lakes Research Division, University of Michigan,
   Ann Arbor, MI 48105

Donald W.  Schults, Corvallis Environmental  Research Laboratory, U.S.
   Environmental Protection Agency, Corvallis, OR 97330

Joseph Shapiro, Limnological Research Center, University of Minnesota,
   St. Paul, MN 55108

D. E. Spyridakis, Department of Civil  Engineering, University of Washington,
   Seattle, WA 98105

Francis S.  Stay, Corvallis Environmental Research Laboratory, U.S.
   Environmental Protection Agency, Corvallis, OR 97330

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Stephen J.  Tarapchak, Great Lakes Environmental  Research Laboratory,
   National Oceanic and Atmospheric Administration, Ann Arbor, MI 48105

David W. Waller, Kent State University, Kent, OH 44240

Charles M.  Weiss, Department of Environmental Sciences and Engineering,
   School  of Public Health, University of North  Carolina, Chapel  Hill, NC 27514

Eugene B.  Welch, Department of Civil  Engineering, University of Washington,
   Seattle, WA 98105


T. Wiederholm, Department of Civil  Engineering,  University of Washington,
   Seattle, WA 98105

Richard F.  Wright, Norwegian Institute for Water Research, Oslo,  Norway
                                     IX

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                             SECTION I - FLORIDA


             ANALYSIS OF TROPHIC CONDITIONS AND EUTROPHICATION

                       FACTORS IN LAKE WEIR, FLORIDA


                      P. 0. Brezonik and J. J.  Messer
              Department of Environmental  Engineering Sciences
                           University of Florida
                           Gainesville, Florida
                                INTRODUCTION
     Lake Weir is a medium size recreational  lake in central  Florida.
Present water quality is good and the lake is classified as mesotrophic.
Uses of the lake are nearly exclusively recreational -- swimming,  boating
and fishing, and many residences along the shore are second homes.   Although
the lake is well-known to sport fishermen, especially for its largemouth
bass, until recently the lake had received no limnological  attention,  per-
haps because of its good water quality and lack of problems.   Background
limnological information on Lake Weir is thus sparse.  Early scientific
expeditions to Florida during the late 1700's by John and William  Bartram
and nineteenth century excursions by J. W. Bailey generally followed water-
ways for ease of transportation; thus Lake Weir, with no navigable streams
entering or leaving it, was apparently missed by these early naturalists
(Yount 1963).  Stage data has been gathered for the lake since 1936, and
a broad-crested, fixed level weir was built in April of 1938 to prevent
possible flood damage resulting from hurricanes.  A bathymetric map drawn
by U.S.G.S. was published for the lake by Kenner (1964).  Lake Weir was
included in a 1969-70 study of 55 lakes in north central Florida by Brezonik
and Shannon (1971), resulting in the first systematic limnological  study  of
the lake.
                       DESCRIPTION OF THE STUDY AREA
     Lake Weir, Florida is located on the Central  Florida Ridge at
the southern edge of Marion Country, Florida, about one third of the
way down the Florida peninsula and midway between the Atlantic Ocean
and the Gulf of Mexico (Figure 1).  The centroid of the lake is at

                                      1

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 Figure 1.  Map  of  Lake Weir area showing major  roads,  cities and
            water bodies.
        16 r  ">
-  15

  13
  12
  11
 ;10
 - 9
 i 8


  5
  •4
  3
  2
  I
                 .IKMAM.IJASONDJFMAMJJASI
                          1973                     1974
                                                             N D
                                                                 80
                                                                 75
                                                                 70
                                                                 65
                                                                 60
                                                                 55
                                                                 50
                                                                    I
Figure 2.
 Mean monthly temperature (continuous  lines),  total monthly
 rainfall  (solid bars) and total monthly wind  miles (open
 bars)  for Ocala, Florida, during 1973 and 1974.

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 29°  1' N,  81° 56' W, and the lake is located in the Lake Weir and Lady
 Lake Quadrangles of the U.S.G.S. 7.5' topographic maps of Florida.
 Little Lake Weir is a smaller basin located to the west of the larger
 lake and is connected to it by an artificial waterway to accomodate
 the  passage of small pleasure boats.  The surface elevation of the
 lakes is 17.4 m above MSL, and the maximum elevation of the surround-
 ing  watershed is 42.7 m above MSL.  The surrounding terrain consists
 of numerous small sand hills, and the high permeability of the soil
 precludes  the presence of permanent surface streams in the watershed.
 Since piezometric maps of the watertable aquifer in the study area do
 not  exist, the area of the watershed was calculated from topographic
 maps.  The Florida Gazeteer of Lakes lists the drainage areas of Lake
 Weir and Little Lake Weir as 130 km2 and 33.8 km2, exclusive of lake
 surface, respectively.  Analysis of the topographic maps, however,
 revealed a more realistic estimate of 22 km2 for the watershed of both
 lakes, exclusive of lake surface.  The surface area of the lake was
 found to be 24.29 km2 including both basins.

       The climate in north central Florida is best described as humid
 sub-tropical, with short, mild winters and long, hot summers.  Average
 monthly temperatures for Ocala, Florida, 25 km to the northwest, sub-
 stantiate this point (Figure 2).   Average annual rainfall in the area
 is approximately 133 cm, mainly occurring in the summer months, fall
 and  spring being rather dry (Butson and Prine 1968).  Summer rains
 usually occur as short, convective afternoon showers, while winter
 precipitation is usually associated with frontal activity.   Although
 the  area experiences occasional frosts during the winter months, the
 total number of hours during which the temperature remains  below 0°C
 averages 50 - 67 hr/yr, and below -2°C, 17 -33 hr/yr (Johnson 1970).
 Wind speed is generally light to moderate, blowing from the north and
west during the winter, but shifting to easterly in the summer.
Hurricanes are seldom in this part of the state.   Evaporation from the
basin during the study period (1974 calendar year) was calculated to
be 122.2 cm/yr,  using evaporation data from a standard Weather Bureau
 pan  at Lisbon, Florida, 24 km to the southeast, and monthly pan coef-
 ficients determined by Kohler (1954) for Lake Okeechobee, Florida.
 Evapotranspiration from the watershed was 27.6 x 10" m^ during 1974,
based on unpublished calculations by S.  Bayley for similar  latitudes
 in the State.

       Two distinct aquifers exist in the area of the lake.   The upper
or watertable aquifer is composed of permeable sand at shallow depth
and clayey sand interbedded with some clay lenses at greater depths
 (Hughes 1974).  This shallow aquifer is underlain with a low-perme-
ability sand and clay formation of Miocene origin called the Hawthorn
Formation (Snell and Anderson 1970).  Below this confining  stratum
lies the permeable Eocene limestone, the Floridan aquifer,  which sup-
plies the State with most of its  drinking water (Faulkner 1970; Snell
and Anderson 1970).   The area surrounding the lake is a principal
recharge area for the Floridan aquifer,  and in places is covered by
only a thin veneer of sand (Snell and Anderson 1970).  Most Florida
lakes are not connected directly to the deep aquifer, as is evident
                               3

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from their soft water (Brezonik et al.  1969).   The General Soil Map
of Florida (Beckenbach and Hammett 1962)  characterizes the soil in
the area as being well-drained to moderately  well-drained, thick to
moderately thick, acid sands of the Lakeland-Eustis-Blanton association.
Because of the high permeability of the soil,  land erosion is not a
problem in the study area, overland flow being virtually absent except
during heavy, long-duration convective storms.

       Approximately 55 percent of the land in the watershed is covered
by mature citrus groves, and the remaining undeveloped land in the
watershed is mainly forested.  The area east  of the lake is dominated
by a pine sandhill association with some mixed hardwoods  (oaks, hickory
and sweet gum).               To the west of  the lake, a scrub (turkey)
oak association is indicative of the nutrient impoverishment of the
well-drained soil.  Cypress are found in marshy areas surrounding the
lake, and willows can be seen on the undeveloped shoreline.  The area
between Lake Weir and Little Lake Weir is a marsh dominated by cattail,
unbrella-grass, and sawgrass.  Some of the shoreline is bordered by
well-manicured lawns.

       An analysis of 1972 aerial photographs indicates 425 residences
in the watershed.  Using an average value of 2.5 persons per single
family rural residence, a population of 1012  persons is obtained for
the watershed.  This amounts to a population density of 46.5 persons
per km .  Interviews with local residents reveal, however, that many
of the residents are seasonal; thus the year-round population is some-
what lower.  The land use characteristics as  determined from the aerial
photographs are summarized in Table 1.  The combination of hilly
terrain, well-drained, high hammock soil, and the propinquity of a
frost-damping deep lake make the area particularly suited for the grow-
ing of citrus crops (Lawrence 1963) which, besides recreation, accounts
for most of the economy in the area.  Many of the homes are built
around the edge of the lake, and three public boat ramps  and several
public and private beaches provide lake access for residents and
visitors.  Fishing for largemouth bass and water sports are popular
activities.  No sewage treatment plants discharge into the lake, and
the residences are served by individual septic tanks.  Because of
the availability of high-quality groundwater from the Floridan aquifer,
lake water is used neither for drinking nor irrigation.
                    MORPHOMETRY AND HYDROLOGY
       A  comparison of  the morphometric characteristics features of
 Lake  Weir (Table  2) with those of temperate lakes of glacial origin
 indicates that  the lake is of rather modest proportion.  Compared to
 sub-tropical Florida  lakes, however, it is one of the deeper lakes in
 the state (Kenner 1964; Brezonik and Shannon 1971).  Hypsographic
 curves for the  lake basins (Figure 2') and the bathymetric map  (Figure
 4) indicate that  the  lake has relatively steep sides, and a relatively
                                4

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Table 1.  Land use characteristics of the Lake Weir watershed.


     J^ricultural land
           (primarily citrus groves)          12,2  km2

     Pasture                                  1.1

     Forest                                   3.5

     Urban (suburban) area                    1.5

     Wetlands                                 3.7


     Total land area                         22.0  km2
         Table 2.   Morphometric features of Lake Weir.


     Surface area
               main basin                   22.78  km?,
               Little Lake Weir              1.51  knu
               total                        2iu29  km

     Maximum length                          5»3   km

     Maximum width                           5.0   km

     Shoreline development index (D^)         1 .7

     Volume                                          ^
               main basin                  1U6.7 x 10,
               Little Lake Weir              5.3 x 10^
               total                       152.0 x 10°
     Itocimum depth
               main basin                   10.1;  m
               little Lake Weir              6.U  m

     Mean depth (both basins)   (iz)           6.3  m

     Volume development index (D^)           1.8

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500     1000      1500      20(10


      Radius (-/A/- ) , m.(»)
                                                        2500
 Figure 3.  Hypsographic curves for Lake Weir.  A:  Little Lake Weir,
            B and  C:  Lake Weir including both basins.
                           LAKE   WEIR
                                                                 \ KM
Figure 4.  Bathymetric map of Lake Weir, Florida.   Bottom contours are
           in feet.
                                 6

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underdeveloped littoral zone (for a Florida lake). The lake is of
solution origin and probably resulted from the fusion of three
dolines; this is a common lake form in areas of karst topography
(Hutchinson 1957; Yount 1963).  The development of volume index (1.92)
and the z/zm value (0.64) are indicative of the relatively flat lake
bottom.  Little Lake Weir has a smaller area/depth ratio than the
larger basin.  Bird Island, located in the southwestern basin and
connected to the mainland by a causeway, was developed by dredge and
fill methods in the 1950's.  Lake volume and elevation are regulated
to some extent by a fixed-level weir at the north end of the lake.
Maximum and minimum lake level elevations for the period of record
are 18.17 and 16.29 m, respectively, but an examination of the hydro-
graph indicates much smaller annual and monthly fluctuations (0.4 m
for 1974 water year).

       At no time during the period of study was there observed evi-
dence of stable stratification of the water column.  This apparently
reflects the lake's large area/depth ratio; stable stratification
occurs in many smaller Florida lakes of comparable depth.  The
largest difference between surface and bottom temperatures observed
was 2.3°C, 1.1°C of which was accounted for in the first meter below
the surface.  This is a common situation in Florida lakes experiencing
intense heating by the summer sun.  Temperatures as high as 30°C were
observed in the surface waters, and the minimum temperature in winter
is about 11°C.  In light of the absence of stratification of chemical
parameters, and considering the long fetch of the lake, it does not
appear that the water column stratifies for more than a few days at a
time.

       The littoral areas of Lake Weir and the center of the big basin
have a sandy bottom, but a loose organic ooze is found in most of the
lake bottom.  In areas covered by Nuphar in sheltered bays and in the
bay north of Bird Island, the sediments are composed of a reddish peat.
The smaller, southwestern basin of the big lake is covered by a gela-
tinous muck.  Organic silt deposits are found in some shallow areas.
The organic muck is dark-gray to brown in color and has a faint odor
of H2S.  The muck in the big lake is thin and unconsolidated, as can
be seen from the depths to which a weighted pail and a narrow pipe
sank at three locations:

              Apparent depth (m)                 Difference (cm)

          Pipe                 Pail

          7.21                 6.80                    41
          7.00                 7.00                     0
          8.02                 7.45                    57

The narrow pipe penetrated the thin sediment, while the broader pail
was stopped more readily.  These data indicate that about a half meter
of thin, unconsolidated sediment occurs in some areas of the lake.
Table  3  gives some chemical characteristics of Lake Weir sediments.
                                 7

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     Table 3.   Chemical Characteristics of Lake Weir sediment*
             Volatile  solids  (%)               54.7
             Total  carbon  (%)                  31.8
             Total  nitrogen  (mg/g)             23.9
             Free ammonia  (mg/g)               -0.15
             Total  phosphate  (mg/g)             0.62
                    C/N                        13.3
                    N/P                        38.5
             Iron  (mg/g)                        3.4
             Manganese (mg/g)                   0.1
              *Results  expressed on a dry weight basis.



Table 4.  Precipitation recorded- at stations near Lake Weir (in cm)


       197U                 Lisbon, EL.       Ocala, Fl.


    January

    February

    March

    April

    May

    June

    July

    August

    September

    October

    November

    December


    Total                      109.B            126.82

        Average  rainfall                119.7
                                8
0.25
U.27
9.07
2.57
9.58
3U.29
17.70
1U.20
10. 3U
0.58
1.65
U.93
0.30
1.60
12.60
1.12
11.8U
Ii0.59
23.16
18.72
12.0U
0.05
1.78
3.02

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Warburg respirometry indicated that the sediments consumed 310 yl 0?
g/dry wt. during a 24 hr period.  This value is intermediate between
the low oxygen demand of oligotrophic lake sediments (50-200 yl C^/g
dry wt.-day) and eutrophic Florida lake sediments (1500-4000 yl 0£/g
dry wt.-day)(Brezonik, unpublished data).  Since Lake Weir is a soft
water lake, there is no CaC03 in the sediment; volatile solids should
reflect its organic content.  The high C:N ratio is typical of Florida
lakes and the high N:P ratio reflects the chemical conditions in the
overlying water.

       Calculation of a water budget for the lake is complicated by
the lack of surface drainage in the sandy watershed.  Water input is
thus the sum of rainfall on the lake surface plus seepage from the
shallow watertable aquifer.  Some surface sheet-flow from the immediate
shoreland area probably occurs during intense rainfalls, but on a
relative basis this is considered a negligible input.  Atmospheric
precipitation is recorded at Ocala (25 km northwest) and at Lisbon
(24 km southeast)  of  the Lake Weir watershed.  While micrometerolog-
ical peculiarities may influence convective precipitation patterns
near the lake, the Lisbon station is located in an area surrounded by
lakes and probably has similar precipitation patterns.  In a similar
hydrologic study on Lake Kerr in the nearby Ocala National Forest,
Hughes (1974) found that averaging rainfall measurements from stations
at this distance resulted in 70-85 percent of the calculated monthly
rainfall averages being within 3 cm of the "actual" value.  The rain-
fall patterns on the watershed are summarized in Table 4.

       On an annual basis the net contribution of groundwater (i.e.
seepage into lake minus groundwater recharge) is small.  The net con-
tribution can be calculated from the formula

                    AS  =  R + (S - GWR) - E - 0

where AS is change in storage, R is rainfall on lake surface, (S-GWR)
is net groundwater contribution (S = seepage, GWR = groundwater
recharge), E is evaporation and 0 is surface outflow.  Outflow occurs
during part of the year over a broadcrested weir at the north end of
the lake and into a canal that feeds into a marsh and eventually to
the Oklawaha River.  All of the above terms except S and GWR can be
directly evaluated:  AS from stage records for the lake, R and E from
rainfall and pan evaporation measurements as described above, and 0
by calculation from the difference between recorded lake stage and the
known elevation of the weir using the formula

                           Q  =  3.3 b (AH)3/2

where Q is flow (in cfs), b is width of weir (in feet) and H is differ-
ence between lake and weir elevations  (in  feet )•  These terms are
tabulated in Table 5, and from the values a net groundwater contribu-
tion of 0.83 x 10 nr* for calendar year 1974 is calculated.

       The above value is misleadingly small in terms of the importance
of groundwater flows into and out of the lake.  Depending on the

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    Table 5.  Water budget for Lake Weir (Calendar 1974)


A.  Water In                                                  106 m3
         Rainfall (Table 4 and Figure 5
           (1.20 m/yr)(24.3 km2)                   =          29.1
         Seepage*                                  =           2.87

                                                 Total        31.97
B.  Water Out
         Evaporation                               =          29.6
         Outflow                                   =           1.1
         Groundwater recharge*                     =           4.96

                                                 Total        35.66
C.  Change in Storage
         Measured:  AS = (-O.lm)(24.3km2)          =          -2.43
         Calculated:  AS = I Inputs - Z Outputs
                         = 31.97 - 35.66           =          -3.69
                           Unaccounted for outflow:            1.26
D.  Retention Time = V/Qout =

                                 152 x lO^m3
         Including evaporation:  — „_   -       =           4.2 yr
                                   JJ . DO
         Including only surface and subsurface outflows:

           152 x 106
           6.06 x 10&


E.  Hydraulic Loading = Qin/A

                      = 8.76 x 104m3/day
                         24.3 x
                                                              0, n
                                                              25'°
* Seepage and recharge calculated by integrating the areas above and
  below the axis of Figure 5, respectively.
                               10

-------
relative levels of the lake surface and the shallow watertable aquifer,
both of which fluctuate seasonally or even weekly, groundwater can flow
into or out of the lake.  Monitoring the direction and magnitude of
these flows would be an extensive undertaking, requiring a network of
wells around the lake.  However the net flow on a weekly basis can be
calculated from the weekly data for all the other hydrologicalpara-
meters.  If one makes the assumption that simultaneous seepage into the
lake and recharge to the aquifer, do not occur, weekly net flows (Figure 5)
probably approximate the gross flows during this time interval, and by
summing over the year the weeks with net seepage and the weeks with
net recharge, the gross flows in each direction can be estimated.  It
should be noted that Lake Weir is evidently not directly connected with
the deeper Floridan aquifer.  The low alkalinity and hardness values
in the lake indicate  no flow of water from this aquifer into the lake.
Also, the piezometric surface of the aquifer in this area lies below
the surface lake evlevation (Mills and Laughlin 1974).  The estimated
water budget and hydraulic retention time for Lake Weir is summarized
in Table 5.
            SUMMARY OF LIMNOLOGICAL CHARACTERISTICS
       The physical and chemical characteristics of Lake Weir are sum-
marized in Table 6 .   The high temperatures are characteristic of Flori-
da lakes (Yount 1963) and probably lead to more stability in the water
column than would occur in colder waters.  Secchi disc transparency
falls within the mesotrophic range defined for low-color lakes by
Brezonik and Shannon (1971).  The low color reflects the absence of
extensive swamps and pine woods in the area, and turbidity is in
the lowest third of the 55 lakes studied by Brezonik and Shannon (1971).
The mean solar radiation on the watershed is 400 langleys/day.

       The chemical data (Table 6 ) indicate a slightly acid lake with
intermediate levels of nitrogen and phosphorus.  Dissolved oxygen is
always high throughout the water column during the day, and it is
unlikely that anoxic conditions ever develop in the water column.
Alkalinity is low,  and the pH is near nutrality, showing little
seasonal variation.  The dominant ions are Na+ and Cl~, the concen-
trations of which are somewhat higher than those in soft water, oligo-
trophic lakes in unpopulated watersheds east of Gainesville, Florida
(Brezonik et_ al_. 1969).  Cultural sources may be responsible for some
of these ions, but there is little other evidence to indicate much
cultural influence on the general chemical composition of the lake.
Iron and manganese are near or below their limits of detection through-
out the water column at all times.  Silica is relatively low and fails
to show a pronounced seasonal trend.

       Levels of nitrogen and phosphorus species are given in Table 7 ,
for the 1974 study period, for the period of maximum insolation, and
for the earlier (1969-70) study.  The mean concentrations represent
arithmatic means for all of the samples taken during the study period,
                               11

-------
(mo)
                                                                                        i
                                                                                       •rl
                                                                                    0)  0)
                                                                                    (0  ,fl
                                                                                    0)  4J

                                                                                   rH  £
                                                                                    co  5
                                                                                   >  rH
                                                                                    rt   en
                                                                                    •u   OJ
                                                                                    tfl   3
                                                                                   T3  i-H
                                                                                        n)
                                                                                    o   F>
                                                                                   •rl
                                                                                    GOT3
                                                                                    O
                                                                                   13  O
                                                                                    0)  4-1
                                                                                    4-J  C
                                                                                    tfl -rl
                                                                                   iH
                                                                                    3  a)
                                                                                    O  £)0
                                                                                   rH  Cd
                                                                                    n)  a.
                                                                                    a  a)
                                                                                        d)
                                                                                    ^  w
                                                                                   <4-i  C
                                                                                        ai
                                                                                   TJ  w
                                                                                    C  cu
                                                                                    3  M
                                                                                    o  a.
                                                                                    n  a)
                                                                                    4-1 rH
                                                                                    0)  CO
                                                                                    
-------
 Table 6.  Physical and chemical characteristics of Lake Weir.
Parameter
Turbidity (JTU)
Secchi disc (m)
Color (Pt units)
Conductance (ymho cm"-'-)
pH
Alkalinity as CaCO-
Acidity2
Cl2
so42
Ca2
Mg2
Na2
K2
Fe2
Mn2
Fe2
COD2
Si022
Range
0.7 - 3.1
1.1 - 2.8
5.0 - 30
16 - 520
5.3 - 7.2
0-54

26.0 - 29.5
4.2 - 8.4
3.6 - 7.8
3.1 - 5.8
10 - 21
1.0 - 3.0

.001 - .03
.16 - .26
16 - 45
0.24 - 0.39
Mean
1.5 + .4
1.9 + .4
16+6
133 + 64
6.6 + .5
11.5 + 6.0
1.0
27.5
6.0
5.3
3.9
14.9
1.9
Trace
.01
.21
28
0.33
•'-Values in mg liter ^- except where units are specified and pH.




2Range of 4-7 measurements during the period 10-68 to 6-70.
                                13

-------
       Table 7.  Summary of nutrient levels in Lake Weir-1-
 Constituent
  1969-19702
Range      Mean
   1974-19753
Range       Mean
Total organic N
Ammonia
Nitrate
Orthophosphate
Total phosphate
0.
0.
0.
0.
0.
67-L07
04-0.55
00-0.06
001-0.014
01-0.055
0.
0.
0.
0.
0.
84
17
035
0065
024
0.
0.
0.
0.
0.
45-1.
005-0
00-0.
005-0
019-0
49
.30
20
.15
.40
0.
0.
0.
0.
(0
90+0.26 (0.98)
038+0.050 (0.018)
033+0.038 (0.019)
025+0.020 (0.022)
.083+0. 062) (0.072)
iResults in mg N or P/£.
^Range and mean of 7 measurements over 13 months.
3Range mean and standard deviation of 15 measurements over 15 months;
 numbers in parentheses represent means during nominal growing
 season (June-October).
     Table 8.  Summary of Biological Parameters for Lake Weir
   Parameter
              1969-1970*
           Range        Mean
                  1974-1975**
               Range      Mean
Phytoplankton
  (cells-filaments/£)

Phytoplankton equitability

Chlorophyll a_
  (mg/m3)

Primary production
  (mg/m^-hr)

Zooplankton
  (organisms/A)
           4.0-10.0
           5-30
    2626     193-2685     1358

                          0.57


     6.0     0.0-33.9     8.2


    12.5        -         7.6
                                 96-403
                          261
 *  Range and mean of 7 measurements over 13 months except for phyto-
    plankton count  which is a single composite sample for May 28, 1969,

**  Range and mean of 11 sampling dates for all but primary production
    which was measured 3 times:  March, August and December.
                                14

-------
regardless of station, depth or date.  Since the lake does not stratify
stably and no pronounced trends were ever observed depth profiles or
areal surveys, the lake can be regarded as essentially homogeneous.
Ortho- and toal phosphate were determined by the Murphy and Riley
single-reagent molybdenum blue method, adapted to the Technicon Auto-
Analyzer (EPA 1971), the total P analysis following digestion with
acid persulfate.  Inorganic N was determined by AutoAnalyzer methods
(EPA 1971), and Kjeldahl nitrogen was determined by Standard Methods
(A.P.H.A. 1971).  Seasonal variations in these nutrients are graphed
in Figure 6.

       Brezonik and Shannon (1971) proposed criteria for common trophic
state indicators for north central Florida lakes based on similarity
(cluster) analysis performed on trophic indicator data from their
Florida lake survey, which included Lake Weir.  They arrived at
ranges for clear mesotrophic lakes of 23 + 14 mg/m^ for total P and
730 + 300 mg/m^ for total organic N.  The values for Lake Weir indi-
cate that the lake exceeds this range for total P, being at the lower
edge of the eutrophic range, but the organic N concentration falls
within the mesotrophic range.  The ratio of total N:total P for 1974
was 13.2 by weight (29 by atoms) which is a considerable decrease from
the average ratio for 1969-70.  Both ratios are indicative of phos-
phorus limitation in the lake biocoenosis.

       The result of an intensive plankton monitoring program are
summarized in Table 8.  Chlorophyll analyses (corrected for phaeopig-
ments) on water samples filtered through 0.8 ym membrane filters indi-
cated that chlorophyll a. was the only important chlorophyll in the
water column; phaeopigments were rarely encountered, except in the
surface samples.  The mean, chlorophyll a_ concentration (8.24 mg/rn^)
for 1974 compares with a mean of 6.0 mg/m^ for 1969-70 and is between
the ranges reported for mesotrophic and eutrophic lakes by Brezonik
and Shannon (1971).  Primary production was measured on three occasions
during 1974 using the   C assimilation method.  The mean volumetric
fixation rate was 7.6 mg C/m^-hr.  These in situ values compare with
a mean of 12.5 mg C/rrr-hr obtained for 7 measurements during 1969-70
using a laboratory light box.  Integrating the in situ measurements
taken over the water column during midday incubations and extrapolat-
ing to daily rates using diurnal productivity curves typical of the
area, yields a very approximate annual C fixation rate of 36 g C/m -
yr.  Again, this represents a value intermediate between mesotrophy
and oligotrophy.

       The phytoplankton of Lake Weir is dominated by blue-green algae
(Cyanophyta).  The dominant plankter during summer 1974 was Oscillatoria
submembranesa Drouet (= Lyngbya digusteii Tiffany).  During the autumn
and winter, Oscillatoria  alternated with Microcystis aeruginosa as
the dominant plankter, depending on the station and date.  An unidenti-
fied coccoid green alga was occasionally dominant in numbers, but was
never important in terms of biomass.  The pelagic diatom, Synedra ulna,
was frequently observed in the summer plankton, but disappeared in
the winter.  Desmids, particularly Staurastrum spp., were always

                                15

-------
      18 -
      16
      U
    e 12
    I 10
             -30
             -20
                        . Chlorophyll a^

                        -Phytoplankton
      1.2
     -I

     S i.o
       .2
 TON


• TOTAL P
                                                0    H    D    J    F    M
Figure  6.   Seasonal variation in  Secchi disc  transparency  phytoplankton,
            chlorophyll a_, and nutrient concentrations in Lake Weir
            during 1974-1975.
                                  16

-------
present.  January 19, 1975, a bloom of Glenodinium quadriens (Pyrrophyta)
in Little Lake Weir resulted in a chlorophyll a_ concentration of 33.9
mg/m^, the highest value observed in the lake to date.  Although
Anabena spp. and Aphanizomenon flos-aquae were occassionally observed
in the net plankton, these species, which are common in eutrophic
Florida lakes, were never of numerical importance.  The mean cell
was 1358  cells-filaments/ml, and there was no pronounced seasonal
trend in plankton counts.  Regression analysis yielded no significant
relationship between chlorophyll ji and cell counts, but a moderate
correlation (r =-0.57) was observed between cell counts and Secchi
disc transparency ,   Equitability was calculated by comparing the
Shannon-Weaver diversity indices against the MacArthur broken stick
model (EPA 1973).  This parameter is thought to be a more sensitive
indicator of stress than the diversity index alone, and the value for
the Lake Weir phytoplankton (.57) is indicative of relatively healthy
biocoenosis.

       Zooplankton were collected and counted from several stations in
the pelagic zone.  The mean concentration and standard deviation of
all of the samples was 261 + 99 organisms/^, with the majority of
zooplankton being immature stages of copepods.  Rotifers were also
abundant, particularly Nothalca sp., and Monostyla and Branchionus spp.
The cladocera were occasionally represented by Bosmina coregoni, an
indicator of good water quality in temperate lakes.

       Dredge transects of the pelagic zone indicated that both the
muck and sand of the large basin were largely devoid of macroinverte-
brates.   As the shore is approached (<100m), the ooze and also the
sand beaches are populated with Sphaeriid clams, a few gastropods,
Hexagenia sp., chironomids, and tubificid worms.  These communities
are never dense (<500 organisms m~2), and diversity was moderate to
high.   The presence of Hexagenia is encouraging, as this organism,
which is particularly susceptible to low dissolved oxygen levels,
provides excellent food for sportfish.

       The unconsolidated sediments in the large basin provide an un-
suitable substrate for submerged flora, but the shallower bays are
covered with Eliocharis elongata and Utricularia sp.  The latter covers
nearly the entire bottom of the bay north of Bird Island.  Potomogeton
illinoensis can be observed growing on the sandy beaches.  The most
conspicuous macrophytes in the lake are the emergent species growing
in the littoral.  The margin of all three basins exhibits a fringe of
Juneus effusus and the grass, Panicum hemitomon, growing out from the
shore as far as 20-25 m, particularly between boat docks and wherever
shelter is afforded.  Juncus grows closer to shore; the Panicum
grows out into depths greater than 2 m.  In the marsh separating
Little Lake Weir from the larger basin, cattail (Typha), bulrush
(Scirpus), sawgrass (Cladium), and Pontederia are the dominant forms.
The bay north of Bird Island displays Nymphoides aquaticum (big float-
ing heart) and patches of spatterdock (Nuphar lutem) which also grows
in sheltered coves.  Although waterhyaciuth (Eichhornia crassipes)
occasionally has been observed in the lake, and along with Salvinia is
                                17

-------
often in nuisance proportions in the canal leading to the outflow weir,
this common pest in Florida waters does not form floating mats in the
lake.
                    NUTRIENT BUDGETS SUMMARY
       One of the most unfortunate difficulties encountered in the study
of Florida watersheds is the virtually complete lack of data for nu-
trient loading rates measured in the State.  The highly permeable sands,
high soil temperatures, unique geology and sub-tropical climate would
seem to make application of temperate zone data to southern watersheds
a questionable procedure.  Nonetheless, with the exception of the data
on N and P in rainfall in the Gainesville, Florida area (Brezonik
et_ a^. 1969), the reviews of Loehr (1974), Chiu et^ al_. (1973), Na-
tional Eutrophication Survey (1974), and Uttormark et_ al. (1974) do
not include a single study on sub-tropical watersheds.  Determination
of a nutrient budget for Lake Weir is further complicated by the fact
that the lake has no surface streams or other point nutrient sources
flowing into it, and all nutrient loading thus is diffuse.  Because of
the dearth of information on nonpoint loadings in Florida, nutrient
loading rates were calculated for the Lake Weir watershed (Table 9 )
using a variety of assumptions and areal yield rates for N and P from
the literature.  In light of this, the loading estimates must be
viewed as only approximate and subject to revision as more becomes
known about nutrient runoff from the land and subsurface nutrient
transport in Florida soils.

       Rainfall nutrient levels were taken from Brezonik et al. (1969)
for rainfall at Gainesville, 60 miles north of the lake.  Urban runoff
values are from Weibel (1969) and represent averages for residential-
light commercial areas found in the study area.  Septic tank contri-
butions were estimated following Brezonik and Shannon (1971).  An
average septic tank was assumed to have a daily effluent flow of 475 £
with total N and P concentrations of 35 and 8 mg/£, respectively.  For
homes located on the lakeshore, 25 percent of the N and 10 percent of
the P were assumed transported to the lake.  These values were reduced
to 10 percent of the N and 1 percent of the P for houses'in the water-
shed not adjacent to the lake shore.  Pasture land and forested land
values were obtained from Uttormark et_ al_. (1974).  In order to take
into account the low nutrient binding capacity of the sandy acid soils
in this area, their "average" and "high" areal yield rates were aver-
aged for these two land-use classifications.   Nitrogen and phosphorus
contributions of citrus groves were taken from estimates by Brezonik
and Shannon (1971) based on the average fertilizer composition and
application rates to the groves.  It was assumed that 10 percent of
the N and 1 percent of the P reached the lake water.  It is generally
agreed (Uttormark &t_ _§J^.  1974; Lee et^ al. 1975) that wetlands of the
general type found in the Lake Weir watershed make no net contributions
of N or P to aquatic systems, although they may affect nutrient con-
centrations by acting as "sinks" during the growing season and as
                               18

-------
            Table 9.  Nutrient Budget for Lake Weir, 1974.
                        Areal Yield Rate      Nutrient Loading Rate
Source
Rainfall
Urban

Pasture
Forest

Agriculture
Septic tanks

Loss through
Area
(km2)
24
1

1
3

12


.29
.5

.1
.5

.8


(g/m2 - yr)
N P
0.58 0.044
0.88 0.11

0.75 0.065
0.37 0.060

2.24 0.018



1
0

0
0

2
0
4
N
.409 x
.132 x

.083 x
.130 x

.867 x
.052 x
.67 x
(g/yr)
10
10

10
10

10
10
10
7
7
7

7
7

7
7
outflow (0 ^ x P )
1
0

0
0

0
0
1
0
P
.06 x
.165 x

.072 x
.216 x

.230 x
.042 x
.79 x
.097 x

io6
10

10
10

10
10
10
10


6
6

6
6

6
6
6
                       out      ave
                         2
Surface loading rate (g/m  - yr)             1.92          0.074

                            3
Volumetric loading rate (g/m  - yr)          0.30          0.012
              z/t  = 6.3/25 =0.25  (without evaporation)
                 w
              z/t  = 6.3/4.2 =1.5  (with evaporation)
                 w
                                 19

-------
"sources" during decomposition in the colder months.   Lake Weir supports
seasonal populations of water fowl, but lack of reliable census
figures make an estimate of their nutrient contributions impossible.
The densities do not appear to be large, however, and this is unlikely
to be a serious source of error.
                           DISCUSSION
       Lake Weir can be characterized as a sub-tropical, low-acidity,
soft water lake, low in color and turbidity, and exhibiting no thermal
stratification.  Although the lake is relatively deep for Florida, the
lack of stable stratification precludes formation of a hypolimnion,
and dissolved oxygen concentrations are high throughout the water
column at all times.  Concentrations of nitrogen and phosphorus are
moderate to high, exhibiting no distinct seasonal trends.  Although
the phytoplankton is dominated throughout the year by blue-green
algae, diversity in this biocoenosis is relatively high, and nuisance
conditions do not occur.  Primary productivity in this community is
low to moderate.  Although macrophytes are common, floating mats of
hyacinths or nuisance growths of Hydrilla, Salvinia, or Pistia are not
found in the lake.  Diversity is relatively high among both the
zooplankton and the benthos, and the presence of Bosmina coregoni and
Hexagenia in these two habitats, respectively, are indicative of good
general water quality.  Largemouth bass and a variety of other sport
fish are abundant.

       Comparability between trophic state indicators in temperate and
subtropical lakes, and perhaps permissable nutrient loading rates as
well, must be viewed in the light of the fundamentally different
patterns of organization in temperate and tropical systems.  Whereas
the former are adapted to a strong seasonal pulse of insolation which
is used to build storages that must tide the community over until
the following spring, the latter is organized around a higher overall
energy input with much less severe seasonal variation (Odum 1971).  In
a temperate lake, the spring overturn coincides with a period of high
insolation, offering the plankton a banquet of readily assimilable
inorganic nutrients regenerated during winter stratification along with
the sunlight necessary to incorporate them into biomass.  While
insolation is lower at the time of fall circulation, a pulse of nutri-
ents from the hypolimnion probably is instrumental in supporting an
autumn algal maximum.  In tropical lakes insolation is relatively high
during the entire year but falls below that of northern latitudes
during the summer.  In many Florida lakes, spring and fall phytoplankton
maxima are replaced by oscillations occurring, seemingly at random,
throughout the year.  It would seem that a system in which a signifi-
cant portion of the nitrogen and phosphorus is tied up in more or less
refractory algal biomass (Gunnison and Alexander 1975) would be unable
to support the same sized blooms, given the same total N and P concen-
trations or loadings, as a system in which virtually the entire nutri-
ent pool is in the inorganic form at a time favorable for algal growth.


                                20

-------
       These differences are important not only in measuring the trophic
status of tropical and subtropical lakes  but may also modify their
critical nutrient loading rates.  Chlorophyll a_ values in nutrient rich
tropical lakes not dominated by motile Pyrrophyta are reported to be
remarkably low (Berman and Pollingher 1974) compared to temperate
lakes of similar trophic status.  Inasmuch as high gross primary pro-
ductivity is reported by these authors, the low chlorophyll values
probably represent "sun" plants with high gross to net production
ratios.  Relatively lower net carbon assimilation rates may be ex-
pected in the spring in subtropical systems, due to relatively lower
vernal insolation and higher maintenance costs of overcoming thermal
disordering at the higher water temperatures.  Berman and Pollingher
(1974) report plankton respiration rates for Lake Kinneret of 40-50
percent of gross photosynthesis.

       Several reported criteria for N and P levels associated with
various trophic states in temperate lakes were reviewed by Vollenweider
(1968).  N and P concentrations in Lake Weir exceed the critical con-
centration for one or both nutrients in every case.  The concentrations
of total N and P fall just above the mesotrophic range for uncolored
north central Florida lakes (Brezonik and Shannon 1971).  Most of the
biological parameters, however, fall within the mesotrophic (or occa-
tionally the oligotrophic) range for either European or Japanese
temperate lakes (Vollenweider 1968; Sakamoto 1966)  or for Florida lakes
(Brezonik and Shannon 1971).   If maximum available nutrient levels
after the season of minimum growth are indeed relatively lower in
tropical than in temperate lakes, maximum biomass during the season of
maximum growth would expectedly be lower in comparably loaded tropical
lakes than in temperate lakes.

       In order to clarify further the trophic status of Lake Weir,
various trophic state indices were calculated for the lake.  The TSI
derived by Brezonik and Shannon (1971) was recalculated for the recent
data and yielded a value of 3.58, within the range for mesotrophic
lakes.  However,  the value has risen from the value (3.30) calculated
from 1969-70 data.  An increase since 1969-70 was also noted in the
concentrations of N and P, and in a decrease in the N:P ratio from 96
(by atoms) to 29.   Little change was noted in the biological parameters,
although chlorophyll concentrations increased somewhat.  It is not known
to what extent these changes  represent experimental artifacts, sto-
chastic elements in the environment, long term system cycles, or the
impact of cultural encroachment on the lake.  The TSI equations
formulated by Carlson (1975)  based on Secchi disk transparencey was
applied to the lake data, and values of 51, 51 and 64 were derived
for Secchi disk, chlorophyll,  and total phosphorus data, respectively.
This would indicate that the  lake falls almost directly in the middle
of a scale based on Secchi disk transparency, but again the nutrient
concentration overrates the lake in the direction of eutrophy.  While
the possibility exists that some of the measured phosphorus is not
available to the plankton, it is still tempting to suggest that higher
nutrient concentrations are required to produce the same standing crop
in southern waters.  The agreement of the trophic state indices with
the more qualitative biological observations in the lake clearly
delineate Lake Weir as a mesotrophic lake.

                               21

-------
       Calculation of the nutrient loading rates for Lake Weir based
on the nutrient and hydrologic budgets presented previously leads to
the values presented in Table 9 .   Plotting areal P loading against
z/tw (Vollenweider 1974), Lake Weir is found to have a P loading rate
which falls within twice the permissable loading for a lake of its
depth and flushing time.  Inasmuch as one of the constraints on this
model is that the lake act as a mixed reactor, Lake Weir should be
an ideal case.  The observed decrease in the N:P ratio in the lake
during the past five years is consistent with a relatively high P
loading rate, while the relatively stable biological system renders
a condition of severe stress unlikely.  It is interesting to note that
the empirical loading rates for Florida lakes by Brezonik and Shannon
(1971) permit higher areal P (and N) loading rates, Lake Weir falling
just above the permissible range for nitrogen and at the maximum per-
missible rate for phosphorus.  This model does not take the flushing
rate into account.
                             SUMMARY
       Lake Weir, Florida, a 2200 ha soft water lake located on the
central Florida ridge, has a watershed dominated by citrus groves and
receives no permanent surface streams or wastewater influents.  Bio-
logical parameters in the lake indicate a diverse,moderately productive
ecosystem which exhibits no nuisance conditions associated with exces-
sive growth of macrophytes or algae.  Two independently derived trophic
state indices bear out biological delineation of the mesotrophic status
of the lake.  Nitrogen and phosphorus concentrations in the lake are
indicative of borderline eutrophic conditions in the lake, and there
is some evidence for a significant increase in phosphorus in the lake
since a previous study.  Lake Weir has a low flushing rate which makes
it sensitive to nutrient loading, and application of lake data to the
Vollenweider input-output model, indicates that areal P loading rates
are just at the danger level.
                           REFERENCES
American Public Health Association.  Standard Methods for the Analysis
     of Water and Wastewater, 13th Ed.  New York, 1971.

Beckenbach, J. R. and J. W. Hammett.  General Soil Map of Florida.
     Florida Agricultural Experiment Stations, 1962.

Berman, T. and U. Pollingher.  Annual and Seasonal Variations of Phyto-
     plankton, Chlorophyll, and Photosynthesis in Lake Kinneret.
     Limnol. Oceanogr.  19:31-54, 1974.

Brezonik, P. L., W. H. Morgan, E. E. Shannon, and H. D. Putnam,  Eutro-
     phication Factors in North Central Florida Lakes.  Florida
     Engineering and Industrial Research Station.  Gainesville, Florida.
     1969.
                               22

-------
Brezonik, P. L. and R. L. Shannon.  Trophic State of Lakes in N.
     Central Florida.  Water Resources Research Center,  Gainesville,
     Florida.  Number 13.  1971.  102 p.

Butson, K. D. and G. M. Prine.  Weekly Rainfall Frequencies in Florida.
     Agriculture Experiment Station Circular, Gainesville, Florida.
     Number S-187.  1968.

Carlson, R. E.  A Trophic State Model for Lakes.  Limnol. Oceanogr.
     1975.  20 p. (in press).

Chiu, S. Y., J. W. Nebgen, A. Aleti, and A. D. McElroy.  Methods for
     Identifying and Evaluating the Nature and Extent of Nonpoint
     Sources of Pollutants.  EPA-430/9-73-014.  1973.

E. P. A .   Methods for Chemical Analysis of Water and Wastes.  Number
     16020-07/71.  1971.

E.P.A.   Biological Field and Laboratory Methods for Measuring the
     Quality of Surface Waters and Effluents.  Number  670/4-73-001.
     1973.

E.P.A.   Relationships Between Drainage Area  Characteristics and Non-
     point Source Nutrients in Streams.  Pacific Northwest Environ-
     mental Research Laboratory, Corvallis, Oregon.  Working Paper
     Number 25.  1974.

Faulkner, G. L.  Geo-Hydrology of the Cross-Florida Barge Canal Area.
     U.S. Geol. Survey, Tallahassee, Fl.  Open-File Report.  1970.
     222 p.

Gunnison, D.- and M. Alexander.  Resistance and Susceptibility of Algae
     to Decomposition by Natural Microbial Communities.  Limnol.
     Oceanogr.  20:64-70, 1975.

Hughes, G. H.  Water Balance of Lake Kerr - A Deductive Study of a
     Landlocked Lake in North-Central Florida.  Fla. Bur. Geol. Rept.
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Hutchinson, G. E.  A Treatise on Limnology.  New York, Wiley, 1957.
     1015 p.

Johnson, W. 0.  Minimum Temperatures in the Agricultural Areas of
     Peninsular Florida.  University of Florida.  Gainesville, Florida.
     IFAS Publication Number 9.  1970.   154 p.

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     Geol. Surv.  Information Circ. Number 40.  1964.  82 p.

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     Lake Hefner Studies.   U.S.G.S. Prof.  Paper.  Technical Rept.
     Number 269.  1954.   127-148 p.

Lawrence, F.  P.   Selecting a Grove Site.   Agriculture Extension Service.
     Gainesville, Florida.   Circular Number 185A.   1963.

                                23

-------
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     1971.  331 p.

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      733 p.
                               24

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                            SECTION II - MINNESOTA


                AN OVERVIEW OF LIMNOLOGICAL CHARACTERISTICS OF

                            SHAGAWA LAKE, MINNESOTA

                 K. W. Malueg, D. W. Schults and D. P.  Larsen

                     U.S. Environmental  Protection Agency
                  Con/all is Environmental Research Laboratory
                               Corvallis, Oregon

                                 INTRODUCTION

     Shagawa Lake, known to the Chippewa Indians as Ga-Shagawigumag-sag  or "long
narrow lake" (Winchell, 1887), is located adjacent to the city of Ely in north-
eastern Minnesota.  The lake, formed during the retreat of the Wisconsin Glacier
about 10,000 years ago, lies in a bedrock basin partially dammed by drift produced
by glacial erosion and deposition.  Significant point-source nutrient enrichment
of Shagawa Lake began in 1901 when untreated wastewater from about 3500  people
was discharged directly into the lake.  Primary treatment began in 1912  and sec-
ondary treatment in 1954.  This nutrient enrichment distinguished Shagawa from
the oligotrophic lakes typically found in this region of Minnesota.  In  1973,
tertiary treatment was initiated for phosphorus removal.

                     GEOGRAPHICAL DESCRIPTION OF THE LAKE

     The lake is located at latitude 47°55'N, and longitude 91°52'W, and at an
altitude of 407.8 m above mean sea level.  The drainage basin covers 269 km2.
About 160 km2 of that includes and drains into Burntside Lake (located to the
NW), then into Shagawa Lake through Burntside River.  The drainage basin below
Burntside Lake and including Shagawa Lake is 109 km2 (Malueg, et al. 1975).

     The climate is relatively severe for the continental United States.  Ice
covers the lake about 6 mo/yr.  For example, the open-water period in 1972 was
from 10 May to 15 November.*  Monthly air temperature and precipitation  averaged
2.8°C and 5.1 cm/mo, respectively.  About 70% of the precipitation fell  during
the open-water season.  Lake evaporation for the open-water season was 7.6 cm/mo,
while the annual lake evaporation value  was 66.7 cm.  Wind direction was gen-
erally from the N or NW.
*A11 data unless otherwise stated are for 1972,  the year prior to operation  of
 the tertiary wastewater treatment plant at Ely.


                                       25

-------
 The geological  formation  in  the area  resists erosion and leaching by
.surface  waters.   The  bedrock consists of  Precambrian, metamorphic rock
 including  granite,  slate,  and greenstone.  A rich  iron ore deposit lies
 along  the  southern  shore  of  the lake.  Overlying the bedrock is a patchy
 distribution  of glacial  sediments  including sand and gravel, plus lucustrine
 silts  and  calcareous  clays that apprently also underlie the organic
 sediments  of  Shagawa  Lake  (Bradbury and Waddington, 1973).

 Forest and marsh comprise  most of  the land, 77% and 15% respectively,
 while  construction  and agriculture use 7% and 1%,  respectively.  Deciduous
 forests  of aspen (Populus  tremuloides) and birch (Betula papyrifera),
 plus coniferous forests  of jack pine  (Pinus banksiana), spruce  (Picea
 mariana),  and fir (Abies  balsomea) are the dominant forms of vegetation.

 In  1888  Ely was incorporated as a  village with a population of  104.  By
 1900 the population had  increased  to  3717 as a result of the developing
 iron mining and logging  industries.   The  population peaked at 6151 in
 1930,  and  has since declined and stabilized at about 5000 residents
 today.   Now the major industry is  tourism, with heavy emphasis  on water
 sports,  primarily fishing  and some "sea plane" activity.

 In  1901  Ely began discharging its  untreated municipal wastewater directly
 into Shagawa  Lake.  Although primary  treatment began in 1912, secondary
 treatment  did not follow  until 1954--and  all treated water was  discharged
 into the lake.   Furthermore, during the mining years of 1884-1967 (Somrock,
 1974)  an unknown amount  of mine sump water was discharged into  the lake.

 That dual  abuse of  Shagawa Lake has produced problems.  Although Shagawa
 Lake was the  original source of Ely's drinking water, in 1932,  the city
 constructed a pipeline to  draw drinking water from nearby Burntside

-------
Lake.  Furthermore, Shagawa Lake was closed to swimming between 1968 and
1972 because bacteria originating from wastewater sometimes exceeded
health standards.

A tertiary treatment plant designed to reduce wastewater total  phosphorus
concentration to <50 yg/1 commenced operation in early 1973, thus reducing
the input of wastewater phosphorus by 99% and the total phosphorus input
to the lake by 70-80%.  Approximately 100 unsewered homes and resorts
which dot the lake shoreline have septic tanks and contribute an unknown
amount of phosphorus to the lake.

Descriptions of Morphometric and Hydro! ogic Characteristics of Shagawa Lake

                                         2
Shagawa Lake has a surface area of 9.2 km  and is approximately 6.6 km
long and 2.9 km wide (Figure 1).  The 34.1 km of shoreline includes 5.1
km of island shoreline.  The lake has a maximum depth of 13.7 m, mean
                                      7  3
depth of 5.7 m, and volume of 5.3 x 10  m .  There is no man-made regu-
lation for depth control.  Natural  volume variation is approximately jj>
of the mean.  The surface area ratio of "shallow" to "deep" waters is
1.54 with the 5.25 m depth arbitarily separating shallow and deep water;
the ratio of volume is 2.75.  A clearly defined hypolimniom rarely
exists.  Summer thermal stratification usually develops in early June
and extends to early September, although gradients are sometimes minimal.

Generally the sediments of nearshore areas are very sandy with little
organic matter, the sediments of the mid-depths are composed of algal
biopel and silt-sized particles, and the sediments of the deep holes are
composed of algal biopel and clay-sized particles (Waddington & Wright,
1974).  Phosphorus primarily exists in the sediments in association with
iron.
                                   2-7

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                        I     I    I         I
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Figure 2      Seasonal  variation of precipitation (cm/mo) for 1972.
             (National Weather Service data).
                              29

-------
                                     7  3
During 1972 water inflow was 6.2 x 10  m ,  approximately 70% from Burnt-
side River and the remainder from minor tributaries,  wastewater,  indirect
flow, and precipitation.  The U.S. Geological  Survey  determined that
groundwater flow was negligible.  The outflow was 6.7 x 10  m .  Malueg,
et al. (1975) present details of the water  budget for the years 1967-
1972.  The water retention time (based upon outflow)  was 0.79 yr during
1972.  Figure 2 summarizes seasonal variation in rainfall.
Water currents have not been surveyed extensively.   Some dye studies
indicate that treated effluent may move along the shore to the east
while other dye studies show movement towards the central  basin of the
lake.  Aerial photographs generally show surface algae "streaming" from
west to east in the lee of islands.

Limnological Characterization of Shagawa Lake

Physical, chemical, and biological sampling and analytical techniques
are summarized in Larsen and Malueg (1975).  Most of the data reported
herein are from that paper and, as such, represent only one sampling
station, Brisson's Point (Figure 1).  Variables were monitored approxi-
mately weekly at 1.5-m depth intervals.

During the ice-covered months, temperatures ranged from near 0°C at the
surface to slightly greater than 5°C at the bottom (Figure 3a).  After
the ice broke up in May, the lake rapidly warmed.  A thermocline developed
in June and deepened during the summer, although thermal gradients were
slight.  Late summer surface temperatures exceeded 20°C while bottom
temperatures were as high as 15°C.  Fall circulation began in early
September, and the lake froze over in mid-November.

The specific conductance was about 65 ymhos/cm during fall circulation
(Figure 3b); values as high as 150 ymhos/cm were observed in the anoxic
deep water during the winter and summer.
                                   30

-------
                                                OJ
31

-------
Maximum pH values of slightly greater than 9.5 occurred in surface
waters during algal blooms; low values of 6.5 were observed in deep
water (Figure 3c).  Under ice cover and during fall circulation, pH
values were generally 7.0-7.5.

During summer stratification anoxic conditions developed below 8 m
(Figure 3d).  In other years anoxia was observed in the bottom waters
during February and March.  Oxygen supersaturation often existed in
surface waters during summer algal blooms.

The average total alkalinity concentration (as CaCO-J was about 22 mg/1
during the fall circulation (Figure 4a).  Summer values ranged from 17
to more than 20 mg/1 in surface waters, slightly exceeding 40 mg/1 in
deeper anoxic waters.

Total phosphorus concentration in surface waters ranged between 0.025-
0.05 mg/1 during most of the year but increased to 0.075 mg/1 prior to
fall circulation  (Figure 4b).  Bottom concentrations exceeded 1.0 mg/1
during anoxic periods.  Soluble reactive phosphorus concentrations
reached 0.6 mg/1  in the bottom waters during anoxic periods but were
depleted in surface waters during most of the summer months (Figure 4c).
Winter concentrations in surface waters often were greater than 0.020
mg/1.

Inorganic nitrogen concentrations were high during the ice-covered
interval, sometimes exceeding 0.20 mg/1, but depletion occurred during
summer months.  Nitrate and nitrite  (Figure 4d) were undetectable during
summer throughout  the lake, but ammonia (Figure 5) increased slightly  in
the surface waters and to more than  1.0 mg/1 in the anoxic bottom waters
prior to fall circulation.
                                  32

-------
                                                  (O
                                               Ol  U
33

-------
           14 0
           14
                              A    M
Figure 5 (top)   Isopleth  of ammonia  nitrogen  (mg/1)  for  1972.   Cross-hatching
                indicates ice cover  (from Larsen  and Malueg,  1975).

Figure 6 (bottom)  Isopleth of chlorophyll  a  (yg/1)  for 1972.   Cross-hatching
                indicates ice cover  (from Larsen  and Malueg,  1975).
                                      34

-------
Major cation concentrations (Ca  ,  Mg  ,  K ,  and Na )  are summarized in
Table 1.  Table 2 summarizes trace  element concentrations.

Average chlorophyll ^concentrations (Figure  6) increased in surface
waters from 1 yg/1 under ice-cover  to 30  yg/1 during the spring maxima,
then decreased to about 10 yg/1.  A summer bloom developed  later raising
the average chlorophyll value to  about 60 yg/1.  Following  fall-overturn,
values declined to 1 yg/1  under ice-cover. Minimum secchi  disc depth
was 1.1 m, maximum was 6.1 m, and the average for the  open  water season
was 2.3 m.

Primary productivity profiles were  obtained weekly or  bi-weekly at one
station (E) using the dissolved oxygen, light/dark bottle technique.
Measurements were conducted over  a  four-hour  interval  from  1000-1400 hrs
                                                       2
(CST).  Maximum areal productivity  values of  260 mg C/m /hr were attained
in late summer (Figure 7)  corresponding to peak chlorophyll ^concentrations.
Extrapolation of four-hour values to daily values -- assuming productivity
proportional to incident solar radiation  and  integrating over time --
                                     2
suggests that approximately 220 g C/m  were fixed during the ice free
season.  Solar radiation weekly averages  as measured with a pyranometer
are summarized in Figure 8.

Laboratory algal assays (National Eutrophication Research Program, 1971)
conducted quarterly during 1972 indicated phosphorus limitation in •
surface samples; however,  nitrogen  limitation was observed  by assays in
other years during the ice free season.

During 1972 the pattern of algal  succession was a spring pulse of greens
followed by diatoms in early summer and blue-greens during  mid to late
summer.  The greens were dominated  by Chiamydomonas sp.; the diatoms by
Synedra spp.; and the blue-greens by Anabaena circinalis, Anabaena
spiroides and Coelosphaerium naegelianum  in early July, late July, and
                                  35

-------
 TABLE 1.   Summary of Major  Cation  Concentrations (mg/1) for 1972

                          3/7       6/6        8/21           11/14
Calcium           OM
                  6M
                 12M
       Bright (1968)

Potassium         OM
                  6M
                 12M
       Bright (1968)

Magnesium         OM
                  6M
                 12M
       Bright (1968)

Sodium            OM
                  6M
                 12M
       Bright (1968)
-
14.2
25.0
10.2
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0.6
0.9
0.78
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2.0
2.8
3.04
—
1.5
2.3
1.6
7.0
8.0
8.0

0.5
0.6
0.6

1.4
2.1
2.1

1.4
1.5
1.4

8.3
8.9
11.1

0.6
0.6
0.7

1.4
2.1
2.5

1.4
1.5
1.6

-
9.1
9.9

0.7
0.7


1.7
2.1
2.1

1.7
1.6
1.6

                                36

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                            38

-------
late August, respectively (Schults et al. 1975).  Protozoans and rotifers
were the most numerous zooplankton in Shagawa Lake, foVIowed by copepods
and cladocerans (Figure 9).  Maximum production of benthos,  dominated
by Chaoborus spp., occurred in October when total organisms reached
20 x 103/m2 (Figure 10).

Macrophytes covered less than 1% of the lake surface.  Dominant species
of emergent vegetation included the bur-reed (Sparganium eurycarpum),
waterlily (Nuphar sp.). pondweed (Potamogeton richardsonii), water weed
(Elodea sp.), and bushy pondweed (Najas sp.).

Dominant fish included Cisco (Coregonus artedii), walleye (Stizostedion
vitreum), yellow perch (Perca flavescens) and the rock bass (Ambloplites
rupestris).

Schults et al. (1975), present further discussion of the phytoplankton,
zooplankton, benthos, fish, and macrophyte communities.

Table 3 summarizes nitrogen and phosphorus budgets (see Malueg et al.
1975 for details).  Wastewater accounted for about 80% of total phosphorus
entering the lake, while tributaries contributed about 15%.  On the
other hand, waste discharges accounted for only about 27% of the nitrogen
entering the lake while tributaries supplied 60%.  About 50% of the
phosphorus and 16% of the nitrogen were retained by the lake-sediment
system.  The amount of nitrogen gain or loss by nitrogen fixation or
denitrification was not determined.

Discussion

Based on the multitude of measured limnological variables,  Shagawa Lake
was classified as eutrophic.  For example, during the summer it exhibited
high pH in the epilimnion, anaerobic conditions in the hypolimnion, low
                                  39

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                                                        cn
                                                        •r- CO

                                                        Of—
                                                        Q- 3
                                                        E -c
                                                        O O
                                                        O t/)


                                                        Q-E
                                           -a r—
                                           C 3
                                           ro (0
                                             .c

                                           O(
                 NOIllSOd^OO !N30d3d
   
 O
 N •>.
  CM
 co r-^

 CO r— i
_1

 (O O

 «"-'
 C7> C
 R) O
^: T-
OO •!->
                                                       cr>
                                                        
-------
        Table 3: Summary of P and N Budgets for 1972
PHOSPHORUS

Source
Wastewater discharges
Tributary runoff
Precipitation
Groundwater
Other (direct runoff - 60; excess
drinking water - 10)
                              Total
Sink (outflow)
kg/yr
5180
 910
  80

  70
                              % retention
6240
3140
  50
NITROGEN
Source
Wastewater discharges
Tributary runoff
Precipitation
Groundwater
Other (Direct runoff - 2800; excess
drinking water - 1100)
Sink (outflow)
                              Total
                         % retention
kg/yr
19300
43300
 5400
 3900
71900
60400
   16
                                  41

-------
Secchi disc values and large variations of nitrogen and phosphorus with
time and depth.  Summer phytoplankton were predominantly blue-green
algae, and chlorophyll values reached about 60 yg/1.

On the basis of data from 17 Wisconsin lakes,  Sawyer (1947)  indicated
that 0.01 mg/1 of inorganic phosphorus and 0.3 mg/1 of inorganic nitrogen
at the time of spring overturn are critical values, above which blooms
can be expected.  In Shagawa Lake the springtime values of soluble
reactive phosphorus and inorganic nitrogen were generally at or above
these levels.

Vollenweider (1968) proposed criteria for classifying the trophic status
of lakes on the basis of specific loading rates of nitrogen  and phosphorus
normalized to mean depth and surface area.  The observed phosphorus and
                                               2                2
nitrogen loadings to Shagawa Lake were 0.68 g/m /yr and 7.82 g/m /yr
respectively, well above the threshold values  for eutrophic  lakes.
Vollenweider (1974) later refined his relationship to take into consider-
ation the mean hydraulic retention time of the body of water as well  as
the mean depth.  Figure 11  shows 1972 phosphorus loading for Shagawa
Lake plotted in this manner.

     Approximately 80% of the phosphorus entering Shagawa Lake and 27%
of the nitrogen were attributed to the municipal wastewater.  In early
1973, processing of the wastewater by tertiary treatment was initiated,
reducing the phosphorus loading to the lake by 80%.  The trophic condition
of Shagawa Lake is changing from eutrophic to mesotrophic as a result of
the greatly decreased loading of this critical nutrient.

During periods of anoxic conditions in the bottom waters, phosphorus  is
released from the sediments.   This phosphorus can be transported through-
out the lake as the thermocline breaks up during passing storms and thus
                                  42

-------
        lOr
  C\J
   -51   1.0
   o
   3
   CO
   ID
   01
   a
   i
   CL
   CO
   O
   I
   CL
0.
      0.01
             'Eutrophic'
                    Shagawa,
                    Lake
                                                    Dangerous
                                                            Permissible
                                                 'Oligotrophic'
O.I
                        1.0
                                10
100
1000
       MEAN  DEPTH /MEAN  HYDRAULIC RESIDENCE TIME  (m/yr)
Figure 11  Phosphorus loading versus  mean  depth/mean hydraulic residence time
           for 1972 (Vollenweider,  1974).
can be made available for algal  growth.  Mass balance estimates demonstrate
this during July-August when internal  loading of phosphorus was of a consider-
able magnitude and did significantly  increase the concentration of phosphorus
in the upper waters during that  time  (Larsen et al., 1975).  This nutrient
transport process has also been  reported for Lake Mendota by Stauffer and Lee
(1973).
                                   SUMMARY
This description of Shagawa Lake, Minnesota includes limnological data obtained
during 1972.   Because the lake has  received municipal wastewaten for 75 years,
it is culturally eutrophic, a condition extremely rare for a lake in this region
of Minnesota.  During the past eight years, the Environmental Protection Agency
has intensively studied Shagawa  Lake  to evaluate lake restoration by wastewater
phosphorus removal. A data summary  of  Shagawa Lake and its drainage basin is
presented in Table 4.
                              Acknowledgements
The authors are indebted  to many  individuals of the Eutrophication and Lake Restora-
tion Branch,  both at Corvallis, Oregon, and Ely, Minnesota, who gave freely of
their time and data, and  without whose assistance this report would not have been
possible.
                                      43

-------
Lake name
Trophic state
Lake type
Drainage area
Lake surface area
Mean depth
Retention time
Mean alkalinity
Mean conductivity
Mean Secchi disk
Mean dissolved
phosphorus
Mean total phos.
Mean inorgan.
nitrogen
Mean chlorophyll a_
Annual productivity
Phosphorus loading
point source
non-point source
surface area
loading
Nitrogen loading
point sources
non-point sources
surface area
loading
Degree of oxygen
depletion in
hypolimnion
                   Table 4
1972 DATA SUMMARY FOR NORTH AMERICAN PROJECT
Shagawa Lake, Minnesota. USA	
                         	   (oligo., meso., eutro)
                         	   (lake impound., estuary)
                         	   (square meters)
                         	   (square meters)
                         	   (meters)
                         	   (years)
                         	   (mg/1)
                         	   (umhos/cm)
Eutrophic
Lake
270x1 O6
9.2xlQ6
22 (fall circulation)
60 (fall circulation)
2.3 (ice-free period)
 0.021
 0.055
 0.160
(meters)

(mg/1)
(mg/1)

(mg/1)
 15  (annual  value)  24  (ice-free  period)   (ug/1)  (uncorrected)
 220
 5.100
 1.150
 0.68
 20.000
 52,000
 7.8
 0.0
                                        (gr/meter /year)

                                        (kg/year)
                                        (kg/year)
                                                 2
                                        (gr/meter /year)

                                        (kg/year)
                                        (kg/year)
                                                 2
                                        (gr/meter /year)
                                        (mg/1)
                    Any other data you feel important
                    Above mean  phosphorus  and  nitrogen
                    values  are  volume weighted means
 based on  samp1p<;
                         pp

                                                     tel
                    weekly at  3  stations at  1.5 m depth
                    intervals.
                                         44

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                              REFERENCES
Bradbury, J. P., and J. C. B. Waddington.   1973.   The impact of European
     settlement on Shagawa Lake, northeastern Minnesota, U.S.A. In:
     Quarternary Plant Ecology.  (H. G. B. Birks  and R.  G.  West, Editors),
     Oxford, England: Blackwells p.  289-308.

Larsen, D. P. and K. W. Malueg.  1975.  Limnology of Shagawa Lake,
     Minnesota, prior to reduction of phosphorus  loading.  Hydrobiologia.
     In press.

Larsen, D. P., K. W. Malueg, D. W. Schults, and R. M. Brice.  1975.
     Response of eutrophic Shagawa Lake, Minnesota, USA, to point-
     source, phosphorus reduction.  Internat. Verein. Limnol.  Vol. 19.
     In Press.

Malueg, K. W., D. P. Larsen, D. W. Schults, and H. T. Mercier.   1975.
     A six-year water, phosphorus and nitrogen budget for Shagawa Lake,
     Minnesota.  J. of Environmental Quality. In  press.

National Eutrophication Research Program.   1971.   Algal  Assay Procedure:
     Bottle Test.  Environmental Protection Agency, Corvallis,  Oregon.
     82 p.

Sawyer, C. N.  1947.  Fertilization of lakes by agricultural and urban
     drainage. J. New England Water Works Assn. 61:109-127.

Schults, D. W., K. W. Malueg, and P. D. Smith.  1975.  Limnological
     comparision of culturally eutrophic Shagawa  Lake and adjacent
     oligotrophic  Burntside Lake, Minnesota.  Amer. Mid. Nat.  In press.
                                 45

-------
Somrock, J. W.  1974.   Incredible Ely.   American Forest.   80:8-11,  54-
     55.

Stauffer, R. E. and G.  F. Lee.   1973.   The role of thermocline migration
     in regulating algal  blooms.   In:   Modeling the Eutrophication
     Process - Workshop proceedings.   (E.  J.  Middlebrooks, D.  H.  Falkenborg
     and T. E. Maloney, Editors)  Utah  Water Research Laboratory,   p.  73-
     82.

Vollenweider, R. A.  1968.  Scientific fundamentals of the eutrophication
     of lakes and flowing waters, with particular reference to nitrogen
     and phosphorus as  factors  in eutrophication.  OECD.   Technical
     Report DAS/CSI/68.27.  Paris, France  182 p.

Vollenweider, R. A.  1974.  Input-output models.  Schweiz. Z.  Hydro!.
     (In press).

Waddington, J. C. B. and H. E.  Wright, Jr.  1974.  Surface sediments  of
     Shagawa Lake.  Unpubl. report to  Environmental Protection Agency,
     Corvallis, Oregon.  41 p.

Winchell, N. H.  1887.   Geological and natural  history survey  of  Minnesota •
     The 15th Annual Report for the Year 1886.   St. Paul  Pioneer  Press,
     Co.  496 p.
                                 46

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                            LAKE SALLIE, MINNESOTA

                                 Joe K. Neel

                            Department of Biology
                          University of North Dakota
                          Grand Forks, North Dakota

                               I.  INTRODUCTION

Lake Sal lie has received nutrients originating in the City of Detroit Lakes
sewage for more than 70 years.  Hastewater discharges, treated and untreated,
have passed through a natural lake and an impoundment enroute to Lake Sallie.
In recent years sewage treatment has been very effective for such parameters
as BOD and coliforms.  This lake also has 168 septic tanks draining toward it.

                         II. GEOGRAPHIC DESCRIPTION

A.  Latitude 46°36'00"N
    Longitude 95°54'12"W
B.  Altitude 399 meters (1,309 feet) above mean sea level
C.  Catchment Area 1,543.6 km2 (382,399 acres)

D.  General Climatic Data

Mean monthly temperatures have ranged from -18.7C (January) to 21.2C (July).
Precipitation since 1968 has varied from 49.53 - 70+ cm per year.  Lake Sallie
is usually ice-covered from mid November until April.  Ice has varied from
15-60 cm in thickness, and has been covered with up to 35 cm of snow.  Pre-
vailing wind direction during open water seasons is usually NNW, but strong
south winds occur from time to time.  Evapotranspiration usually exceeds pre-
cipitation by about 25 dm (10 inches) per year, but in the 1973-74 water year
it exceeded precipitation by only 5 cm.

E.  General Geological Characteristics

Topography of this area was primarily formed by Pleistocene glaciation.  Four
lobes of the Wisconsin ice sheet advanced into Minnesota, and two, the Wadena
and Des Moines lobes, formed'this watershed.  The Wadena lobe, moving westward,
formed a hilly region to the east which was later overridden by the Des Moines
lobe moving east and carrying grey till, which was deposited on the moraine
when the Des Moines lobe withdrew.  Outwash areas were formed to either side.

Soil in the morainic eastern 1/3 of the watershed is medium textured sandy loam
which developed from calcareous glacial till; that in the central part consists
of coarse to medium textured well drained materials formed from glacial outwash;
and that in the western 1/3 is dark, well drained glacial  till.  Outwash de-
posits are from 1  to 24 m thick, and the glacial till exceeds 91 m.

Large ice blocks broken off the Des Moines lobe were covered or partially cov-
ered by outwash and their melt formed Lake Sallie and others in the watershed.

                                      47

-------
These lakes are circular or elliptical  of the type called kettle holes.

F.  Vegetation

The catchment area has the following cover:

          1.  Forests  23%
          2.  Water areas and marshlands  29%
          3.  Pastures and croplands  45%
          4.  Urban and residential areas  3%

Forest cover is largely  deciduous, containing oak, maple, aspen,
birch, basswood, cottonwood, ash, and scattered conifers.  Marshes are
largely covered'with cattails and bulrushes, but some wild rice is
present.  Agricultural lands are devoted to small grains, hay, and
pasture.

P.  Population

This watershed is a popular vacation area and a large share of its
population is transient during open water seasons.  The City of Detroit
Lakes had 7,000 residents in 1970 and the permanent population of
suburban dwellings was around 2,000.  Lake Sallie has 168 cottages on
its shores that house mostly temporary residents.

H.  Land Usage

Fifty two percent of the land (forest,  water, and marshlands) is used
for recreation.  Forty five percent is  used for farming - small grains,
hay, livestock pasture, and turkey rearing; 3% is residential and urban.

I.  Use of Water

Groundwater supplies all domestic and industrial water, and surface
waters are used almost exclusively for recreation - swimming, boating,
water skiing, fishing, etc.  Known groundwater consumption is about
3,800-m3 (1 million gallons) per day; many residences have private
wells and withdraw unknown quantities.   A limited amount of commercial
fishing is intermittently carried on in Lake Sallie in autumn.

0.  Sewage and Effluent Discharge

As previously indicated, 168 cottages have septic tanks draining toward
Lake Sallie.  Municipal sewage from the City of Detroit Lakes goes to a
conventional treatment plant (settling, sludge digestion, biofiltration)
This plant effluent goes to an aeration pond whose effluent passes into
a stabilization pond, which overflows to a natural peat area that
discharges to a natural lake, Lake St.  Clair.  This lake overflows into
a ditch that joins the Pelican River above Muskrat Lake (see Figure 1).

-------
                                     STABILIZATION
                                        LAGOON
                                                        ff\T*
                                                        CITY OF
                                                        DETROIT
                                                        LAKES
            500   1000
     SCALE  IN METERS
                                                   WASTE
                                                  TREATMENT
                                                   PLANT
Figure 1.  Flow route of wastewater effluent from Detroit lakes to Lake Sallie.
                               49

-------
       III.  MORPHOMETRIC AND HYDROLOGIC CHARACTERISTICS

A.  Surface Are 5.3 km3 (1,310 acres)
    Maximum Length 3.32 km (2.06 mi.)
    Maximum Width 2.01 km (1.25 mi.)

B.  Water Volume  33,700,262 m3 (27,318 acre feet)

Regulating structures across the Muskrat Lake outlet (see Figure 1)
permit control of Pelican River inflow into Lake Sallie during all but
extremely high runoff periods.  Operation usually strives to maintain
the lake at the "normal" overflow level, but inflow is sometimes
insufficient and many times in excess of manageable quantities.

C.  Maximum Depth 16.5 m (55 ft)
    Average Depth 6.35 m (21 ft.)

D.  Exceptional Depths

Deep pockets underlie very small portions of the surface area of Lake
Sallie (Figures 2).  The area north of the hilus in the bean shaped lake
contains most deep water, and the area south of this point is practically
flat between shoreline slopes.  Percentages of surface area lying between
selected depths are:

          Depths                                  % of area

          0-1.52 m (0-5 ft)                         15.85
          1.52-3.05 m (5-10 ft)                     19.81
          3.05-4.57 m (10-15 ft)                     7.36
          4.57-6.09 m (15-20 ft)                     6.80
          6.09-9.14 m (20-30 ft)                    44.71
          9.14-12.19 m (30-40 ft)                    4.90
          12.19-15.24 m (40-50 ft)                    0.38
          15.24-16.50 m (50-55 ft)                    0.19
E.  Ratio of Epi- over Hypolimnion

This varies from year to year and during any one year.   The thprmocline
has disappeared and reappeared during some summers, and it generally
tends to sink as summer progresses.   Epi-/hypolimnion quotients have
ranged from less than 1 to about 18 at the onset of stratification and
have usually increased to 250 or more before the disappearance of the
thermocline.

F.  Duration of Stratification

          1969 - July 15 to September 14
          1970 - June 6 to 26
          1971 - June 3 to 10
                 June 15 to July 21
                 August 12 to 20
          1972 - June 8 to August 4
                 August 14 to 22
                                  50

-------
    FROM FOX
       LAKE
                                                      MUSKRAT
                                                        LAKE
                                               660  1320
                                               -risori
                                          SCALE IN FEET

                                          0    250   500

                                          SCALE IN METERS
Figure 2.  Bathymetric map of Lake Sallie, Minnesota.
                          51

-------
          1973 -  June 6  to September  7
          1974 -  July 10 to July  31
                 August  21  to  28

G.  Nature of Lake Sediments

Shoal  areas, about 45% of the  bottom, are  largely  sand, and deeper
regions are mostly covered with silt  and clay.   Particulate organic
matter overlies sand in  shoal  pockets and  entire bottoms  in deepest
areas.  Shallows  have bottoms  consisting of 75%  sand,  but deeper
regions have but  25%.

H.  Seasonal Variation of Monthly Precipitation

Generally, highest precipitation  has  occurred  in May,  June, July and
August, and lowest in December-February.  During some  years (1971,
1972, 1973) precipitation was  high in late summer  and  early autumn.

I.  Inflow and Outflow of Water

                     1969      1970      1971       1972        1973

Inflow (m3 x  106)
 Surface inflow      20.22     17.84      17.85     17.39       26.47
 Ground inflow        2.49      1.24       2.96      3.10        4.18
 Total inflow        22.71     19.08      20.81     20.49       30.65
Outflow, surface     22.71     19.08      20.81     20.49       30.65*

 * 3 mos. estimated
J.  Water Currents

Other than in the immediate vicinity of the Pelican River inlet,  all
currents are wind generated during open water seasons.   Maximum waves
are produced by southern and NNE winds.  Pelican River and other  inflows
are more readily detected under ice when they escape wind mixing.

K.  Water Renewal (Retention) Time

Retention time (all inflow) has ranged from 1.09 to 1.76 years  as
shown below.
                                         Years Detention
  Water Year                   All Inflow            Surface Inflow

    1969                         1.48                    1.66
    1970                         1.76                    1.88
    1971                         1.61                    1.88
    1972                         1.64                    1.94
    1973                         1.09                    1.27
                                 52

-------
               IV.   LIMNOLOGICAL CHARACTERIZATION

A.  Physical

    1.   Temperature

Water has responded rather quickly to seasonal  air temperature changes,
and surface and bottom waters have usually differed  in summer and always
in winter.  In winter water has usually been about 3°C warmer at bottom
than at surface, but during periods of summer stagnation it has been as
much as 10°C cooler near the bottom.  Temperature has ranged from 0-27°C.
For data on stratification see F under III above.

    2.   Conductivity

This parameter has  varied by as much as 50 umhos/cm in different lake
surface areas on the same date.  It has generally been lowest at the
outlet (240-280 umhos/cm) and highest (290-360) at the Pelican River
inlet.   It also increases with depth with advanced thermal  stratification
(as much as 40 umhos/cm between surface and 9 m).

    3.   Light

Surface light intensity measurements have varied from less  than 400 to
7,720 foot candles.  Declines to less than 5% of surface intensity have
usually occurred at 3 m.  No light has been observed to penetrate ice
cover,  even the minimum (25 cm) considered safe for observers, but
there is indirect evidence that this has occurred.  Light penetration
was commonly restricted by plankton, especially blue-green  algae,
during open water seasons.  The 1% incident radiation level usually
occurred at 3-3.5 m but in autumn sometimes went as deeply  as 8.5 m;
very faint light was occasionally detected at 10 m.  Red and green
wave lengths usually had greater intensity and range than blue, but
their penetration was often controlled by dominant phytoplankton
pigments.  Red penetrated more deeply when blue-greens and  diatoms or
diatoms alone were  predominant, but green reached greater depths when
greens and blue-greens or greens alone were dominant.

    4.   Color

This measurement has not been conducted at Lake Sal lie.

    5.   Solar Radiation

This feature has been recorded since June 1971  with few interruptions.
It has been most intense in July and August (daily means of 500-560 ly)
and least in December (daily mean 100 ly).  The maximum daily figure
has been 708 ly in  July and the minimum 42 ly in December.

B.  Chemical

    1.   pH

Surface waters have had pH above 8.0 at all seasons, but deepest water
has fallen below that level with summer and winter stagnation.  Some
                                53

-------
littoral areas have ranged below and above 8.0 depending on the nature
of ground and surface inflow.   These data indicate virtual  isolation of
upper waters from deeper areas with significant decomposition most of
the year, widespread photosynthetic dominance in upper waters, and a
relatively minor water volume  noticeably affected by decomposition.
Upon a few occasions pH increases in surface water under ice suggested
photosynthesis although light  could not be detected there.   These
elevations were accompanied by oxygen increases.

     2.  Dissolved Oxygen

Oxygen was never deficient in  surface water and its concentration was
frequently determined by photosynthesis which often produced
supersaturation.  Maximum levels were usually produced by littoral
macrophytes and attached algae which were often responsible for oxygen
pulses.  Thermal stratification often occasioned depletion  in deeper
waters, summer and winter, but oxygen always occurred in limnetic
surface water, even under thickest ice and snow covers.  Photosynthetic
oxygen production occurred under ice cover which has already been
mentioned with reference to pH.  An increase of 3 mgl* was once noted
over a 7-day winter period.

     3.  Phosphorus

Soluble reactive phosphorus (SRP) was concentrated in deeper waters
during stagnation periods, but it  tended to disappear from limnetic
surface waters during growing  seasons, although this rarely occurred
in 1969.  It was missing in surface water from mid-September 1972 until
early March 1973.  It was usually rather low in surface water in most
areas from (0-0.5  mgl) but it became rather heavily concentrated in
some littoral areas, especially under ice cover (maximum 4.8 mgl).
Concentration in the Pelican River inlet was invariably greater than that
in the outlet.

Total phosphorus variation in  general resembled that of soluble
reactive phosphorus, but concentration was usually higher.   It increased
with depth, declined from winter maxima during the growing  season, and
was always more concentrated in incoming than in outgoing water. Total
phosphorus as used here is that secured by oxidation with potassium
persulfate.

     4.  Nitrogen

         a.  Ammonia Nitrogen

This form of nitrogen was present in every water sample taken from
Lake Sallie, no matter what depth or season.  It was most concentrated
in deeper waters during stagnation periods (up to 3.10 mgl  in winter
and to 2.6 mgl in the summer).  Maximum concentrations in limnetic
surface waters (up to 1.25 mgl) occurred during periods of  full
circulation when accumulations built up in deeper waters were reduced.
Surface concentrations varied  in different lake regions.  Values above
4.0 mgl were observed under ice in ground water inflow.  The Pelican
River inlet and three other littoral areas had ammonia concentrations

*In this report mgl  means milligrams per liter
                                54

-------
above those of the general  lake surface.   All  such  areas  had  inflowing
surface or ground water.   Concentration in surface  limnetic water was
almost without exception  greater than 0.1  mgl  and usually more  than 0.2
mgl.  Ammonia nitrogen was  generally more  concentrated in the Pelican
River inflow (Station 1)  than in the lake  outlet  (Station 8).

       b.  Nitrite Nitrogen

This form was often, but  not invariably,  found in samples from  all lake
regions and depths.  It disappeared from all  sampled areas in August
1969 and from surface waters during much  of summer  and autumn 1972.
Concentration was usually well  below 0.01  mgl  at  all  depths during open
water seasons, but it increased to 0.1  in  the  inlet and limnetic waters
briefly in September 1970.   During stratification,  maximums were found
at 6 meters under ice and at intermediate  to maximum depths with open
water.

       c.  Nitrate Nitrogen

Nitrate was most concentrated under ice cover.   It  was most abundant
at 6 and 8 m during the 1969-70 winter and at 14  m during the 1970-71
winter.  The Pelican River  inflow generally had higher values than its
outflow.  NOs was rarely  absent from surface water during open  water,
and never under ice cover.   Concentration  never quite reached 0.4 mgl
and was usually less than 0.1 mgl.

     5.  Alkalinity

Carbonate alkalinity was  present in limnetic surface water at all
seasons, was absent from  deeper waters  during stagnation  periods, and
from some littoral areas  at intervals,  e.g., in areas with ground water
entering under ice cover.  It reached 100  mgl  (as CaC03)  in Muskrat
Lake discharge, and 48 mgl  in the limnetic zone.   It increased  slightly
under ice cover in response to photosynthesis.

Minimum bicarbonate concentrations were recorded  in surface water, and
its limnetic maxima in deeper waters during periods of stratification.
Its maximum in the limnetic zone was 230  mgl  in winter.   Higher values
(up to 428 mgl) were noted  where ground water inflow was  isolated by
ice cover in some littoral  areas, and in winter Pelican River inflow.
HCOa was photosynthetically reduced to 124 mgl  in upper limnetic water.

     6.  Calcium and Magnesium

In limnetic areas Ca ranged from slightly  less than 60 to 100 mgl,
whereas magnesium has varied from slightly more than 100  to 165 mgl.
Highest values for each were in deepest water during stagnation periods.
Groundwater entering the  lake in littoral  areas had higher levels, and
in it Ca exceeded Mg.  Preponderance of Mg in  surface waters  fed by
such groundwater indicates  photosynthetic  overshadowing of decomposition.
Both ions increased when  C02 appeared in  the hypolimnion, but Mg to a
greater extent.

                                  55

-------
C.  Biological

    1.  Phytoplankton

        a.  Chlorophyll

No chlorophyll determinations have been made to date as  this  procedure
has not entered into project objectives.

        b.  Primary Production

This feature has been measured over two hour incubation  periods  using
the light and dark bottle technique.   Reproducibility was  within +10 mg
C fixed/m3/hr.

Phosphorus and nitrogen declined along the path of Pelican River inflow,
and this was true of the rate of primary production on many but  not all
dates of measurement.  It was often greater in the mid-limnetic  area
than near the inlet.  Horizontal variation in the limnetic zone  appeared
normal.

Most measurements were made near the center of the limnetic zone.
Surface water there has shown maxima in late summer or early  fall, but
activity has varied considerably over the seasons.  Patterns  for the
euphotic zone have resembled those for surface water, but  generally
have had fewer and sharper peaks.  Means over the euphotic zone  were
comparable to those of surface water in 1969 and '71, but  were much
lower than the surface in 1970.  Maximum production levels increased
following weed harvest which began in 1970 as follows:

                                           Maximum gross primary
                                           production (mg  C fixed/m3/hr)

            1969                                    435
            1970                                    650
            1971                                    645
            1972                                    780
            1973                                    720
            1974                                    970

This would make it appear that there was considerable competition
between phytoplankton and macrophytes.

Productivity varied with depth in the euphotic zone and  with  time of
day, but with no consistent patterns.  There was no definite  relationship
with intensity or amount of light on a daily or seasonal basis other
than some suppression of activity at noon on bright summer days.
Photosynthetic efficiency (mg C fixed/m3/ly) was usually greatest in
late afternoon, and seasonally in autumn.

        c.  Algal Assays

Collections through 1974 have yielded 131 algal species: 59 green algae,
38 diatoms, 25 blue-greens, 3 dinoflagellates, 1 cryptophycean,

                                 56

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3 euglenophytes, 1  chrysophyte, and 1  xanthophyte.

Annual succession patterns have varied with location in the lake, and
have been unstable  at periods with changing dominant groups.   In the
central limnetic zone the most frequent tendency was dominance by
diatoms in spring,  blue-greens in summer,  diatoms again in autumn, and
green algae or cryptophyceae in winter.  This was by no means a fixed
successional order.  Blue-greens were  sometimes dominant for short
periods in winter,  diatoms were noted  to temporarily or permanently
usurp dominance from blue-greens in summer, and diatoms were at times
replaced in dominance by blue-greens for varying periods in autumn.
Vacillating dominance between diatoms  and blue-greens that often
occurred in late spring and early fall suggests that competition
between them is rather finely balanced and that swings to either side
may result from minor environmental changes.

Phytoplankton composition as larger taxonomic groups differed
noticeably at any time in varied limnetic and littoral areas, and at
different depths in the central limnetic zone.   Variation at the
generic level was often noticeable during periods of dominance by a
single class or order.

         d.  Count

Concentration has varied from 12,000 to more than 66,000,000 units per
liter.  Seasonal influences appear to  result in spring, summer, and
autumn maxima, and  winter, late spring, and late summer minima.  Diatoms
have been largely responsible for spring and fall elevations and
blue-greens for major summer growth, but this has not been a fixed
pattern.  Diatoms once replaced blue-greens in summer.  Green algae
never contributed significantly to annual  maxima but had about 5 peaks
per year, three in  summer and one each in spring and winter.   They
were dominant only  with low total phytoplankton concentrations in
winter.  Greatest total concentrations (more than 50,000,000/1)
observed (outside plankton drifts) were during diatom dominance in
spring, and usually at some distance below the surface where numbers
may have been enhanced by settling. Highest summer concentrations of
blue-greens were considerably lower, ca 6,000,000/1.

     2.  Zooplankton

         a.  Identification and Count

Zooplankton samples have yielded 27 species of Protozoa, 1 nematode,
1 gastrotrich, 20 rotifers, 1 tardigrade, 6 cladocerans, 3 copepods,
1 ostracod, and larval water mites. The most numerous protozoan
(Coleps) attained very great concentrations (500,000/1) in deep water
each summer.  Bosmina longirostris (0. F.  Mull) and Chydorus
sphaericus (0. F. Mull) have been the  most abundant cladocerans, and
Trichocerca similis Ehr., J_. multicrinis Kel 1., and Keratella
cochlearis (Gosse)  the most numerous rotifers.   Halteria, Didinium,
Strombidium, and Vorticella were common protozoans.

                                 57

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     3.  Bottom Fauna

To date benthos has not entered into the Lake Sal lie study program.

     4.  Fish

No detailed examination of nekton has been undertaken, but data on
number of fish species is available from the Game and Fish Division
of the Minnesota Department of Natural Resources.  Species assayed
for carbon, nitrogen and phosphorus content, and these values as
percent of wet weight were:

                                             % of wet wt.
   Fish Species                            C      N       P
 Catostomus commersonii (Lac.)            9.97   1.99    0.49
 Esox lucius L.                           9.11   2.61    0.57
 Ictalurus natal is (LeS.)                 9.39   2.25    0.54
 I. nebulosus (LeS.)                      9.31   2.02    0.55
 1. me!as (Raf.)                          9.18   1.97    0.50
 Lepomis gibbosus (L.)                    8.68   2.06    0.71
 L_. macrochirus Raf.                      8.52   1.84    0.85
 Perca flavescens (Mitch.)                9.49   1.83    0.59
 Porno/is neqromaculatus (LeS.)            9.76   1.95    0.73
 Stizostedion vitreumTMitch.)            7.91   1.84    0.60
Over the period 1969-73 Ictalurus melas was the most abundant species
and accounted for the greatest weight of fish removed by commercial
and sport fishermen.  Estimates of total biomass of fishes in the lake
made by the Game and Fish Division are:

                          1969 - 347,545 kg.
                          1970 - 212,090 kg.
                          1971 - 594,740 kg.

     5.  Bacteria

Bacterial observations have been limited to forms microscopically
identifiable in plankton samples (Sphaerotilus natans).  Under ice this
species has comprised up to 70% of the plankton population in some
littoral areas.

     6.  Bottom Flora

In addition to macrophytes the bottom bore growths of Chara sp.,
Cladophora sp., Rhizoclonium SP., and Nostoc.  The two filamentous
algae were often attached to macrophytes as was Lemma trisulca L.,
which was also free floating.   Spirodela polyrhiza L. and Wolffia
Columbiana Karst. also occurred as surface floaters.

     7.  Macrophytes

This population has to date included the following species:
                                 58

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              Najas flexiles (Willd.) Rostk. and Schmidt
              Potamogeton amplifolius Tuckerm
              P_. en's pus L.
              P.. filiformis var. Macounii Marong
              P.. pectinatus L.
              P.. praelongus Wulf.
              P.. Richardsonii (Benn.) Rydb.
              Ruppia maritima L.
              Alisma qramineum var. Geyeri (Torr.) Sam.
              Scirpus actus Muhl.
              Heteranthera dubia (Jacq.) MacM.
              E1 odea canadensis Michx.
              Vallisneria americana Mi chx.
              Ceratophyllum demersum L.
              Myriophyllum exalbescens Fern.
              Nuphaj^ varieqatum Engelm.
              Nymphae tuberosa Paine
Prior to weed harvest macrophytes covered about 34% of the lake area,
all above the 3 m contour except Potamoqeton praelongus which grew down
to 6 m.  Northern and southern ends of the lake were then dominated by
Myriophyllum and P_. pectinatus.  Weed harvest began in 1970 and in 1971
all species listed above were still present but noticeably less
abundant.  P_. pectinatus was more prominent than Myriophyllum and most
luxuriant growth had changed from northwestern to west and southern
areas.  In 1972, following 2 years of weed harvest, Myriophyllum was
becoming rare, and a previously rare species, P_. crispus, dominated
wide areas in the northern half of the lake.  Weed growth in
harvestable areas declined each with harvest as shown by total mass
removed each year:

              1970 - 428,034 kg wet wt.
              1971 - 111,064 kg wet wt.
              1972 -  59,487 kg wet wt.
              1973 - Practically nil in harvestable areas


                  V.  NUTRIENT BUDGETS SUMMARY

A.  Phosphorus
                                        Kg/water year
Source               1968-69     '69-70     '70-71     '71-72     '72-73
Waste Discharge       10,020      7,060     15,169     20,081     20,519
Land Runoff              100        410        474        176      5,966
Precipitation            -          -           18          9        -
Ground Water           1,345        620      1,480      1,552      2,063
Total                 11,465      8,090     17,141     21,818     28,548
                                  59

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B.  Nitrogen

Source                       1968-69     '69-70     '70-71      '71-72
Waste Discharge               11,360      5,590     10,568       6,930
Land Runoff                      290        260        610          94
Precipitation                    -          -           175         240
Ground Water                     -          -         3,410       8,752
Total                         11,650      5,850     14,763      16,016


                        VI.   DISCUSSION

A.  Limnological Character

Prior to cultural enrichment Lake Sal lie was probably middle-aged
(late mesotrophic or early eutrophic as these  terms  refer to aging).
The large epilimnion/hypolimnion quotient that usually occurs does not
produce a major isolation of nutrients, and summer stagnation is
usually interrupted.  It would therefore appear that naturally
occurring nutrients were generally available during  the growing
season, and that quantities  tied up in the hypolimnion were often made
available at intervals-during summer.   The major water mass probably
supported photosynthesis as  it does today, but intensity and
persistence were less.

Lake Sal lie is a moderately hard, moderately alkaline lake, and neither
calcium nor bicarbonate appears limiting to plant growth or
photosynthesis.  Its epilimnion retains a photosynthetically imparted
character the year around, and is evidently influenced by photosynthesis
at times under ice and snow cover.  Although containing considerable
nutrients and highly productive, the major water mass is remarkably
free from decomposition effects.  Photosynthesis affects all water
during full circulation periods and stratification isolates relatively
small volumes.

The lake has a detention period of about 1.5 years and the  major
surface inflow (Pelican River) sometimes forms interflows under ice
cover that may pass on through the lake.  Ice  cover also permits many
lesser inflows to demonstrate their individuality which is  never evident
in wind driven open water.  Some inflow induces oxygen!ess  conditions
over a few hundred meters of shoreline under ice, but no such effects
are evident during open water.

The plankton population is not dominated by any major group for any great
length of time.  Diatoms have produced more biomass  than any other
phytoplankton group, and they have been involved in  some of the most
intense primary production.   They have usually been  dominant in cooler
open water periods, spring and autumn, but have sometimes replaced
blue-greens in predominance in summer.  Blue-green phytoplankters
generally dominate in the hotter months, but have appeared  liable to
usurpation by diatoms even then.  Blue-green maximums have  been about
11% of those achieved by diatoms, but their denser populations have
been much more noticeable macroscopically.  Dominant groups have varied
in different lake regions at all seasons, in both littoral  and limnetic
zones.                           60

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B.  Delineation of Trophic State

Lake Sallie today may be classed as a culturally enriched,  late
mesotrophic or early eutrophic lake.   The latter two terms  are  used as
they refer to natural aging.

C.  Trophic State vs. Nutrient Budgets

Nutrient budgets vary from year to year but they have been  adequate to
maintain a high level of plant growth.  Attempts to reduce  nutrients
to less productive levels by weed harvest have been a signal  failure,
as they have removed only a small percentage of the annual  phosphorus
increment.  Removal of all fish and weeds would make inroads  on
previously accumulated nitrogen, but would not equal any annual
phosphorus increment observed to date.  The only practicable  method
for P reduction now appears to be great reduction,  or perhaps virtual
elimination, of quantities entering in surface inflow.   Phosphorus
removal procedures are scheduled to be applied to the municipal waste
effluent beginning in autumn 1975.  Response of the lake to nutrient
reduction will be studied concurrently.

Phosphorus loading has varied from 1.52 to 4.16g./m3/yr., depending
upon character of the wastewater effluent and inflow volume.  The  second
Vollenweider number, depth/detention time, is 4.2.   Detention time  used
(1.51 yrs.) is based on both surface and groundwater inflow;  surface
inflow alone would give a detention of about 1.80 years, and  a  smaller
Vollenweider number (z/Tw).  If data for Lake Sallie are plotted on
the L - T/Tw curve (Figure 3, Vollenweider and Dillon,  1974)  any L
figure (gP/m2/yr.) within the above range would place this  lake in  the
eutrophic range, and the higher value (4.16gP/m2/yr.) would put it  well
above the "dangerous" limit.   Actually, Lake Sallie has developed
nuisance conditions each recent year of record that would place it
above the "dangerous" condition with P loadings ranging from  1.52-4.16g/
m2/yr.  This would suggest that above certain loadings  P is no  longer
controlling or that the Vollenweider-Dillon curve needs further
modification.

                         VII.  SUMMARY

Lake Sallie is a kettle hole lake formed by an ice block left in
outwash as the Des Moines lobe of Wisconsin glaciation retreated from
northwestern Minnesota.  The lake now lies in sand and sand and gravel.
Its catchment area (1,544 km2) is covered by forest (23%),  water
bodies and marshlands (29%), pastures and croplands (45%),  and urban
and residential areas (3%).

The lake area is a summer vacationland with a large transient population.
The nearby City of Detroit Lakes had a 1970 population of 7,000, and
2,000 more reside in suburban areas along lake shores.   Lake  Sallie
has 168 cottages along its shores that house mainly transient residents.

On the basis of age classification Lake Sallie is in a late mesotrophic
or early eutrophic state and is culturally enriched by wastewater

                                61

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effluent from the City of Detroit Lakes,  septic tanks  along its shores,
and ground water inflow from agricultural  lands and distant residential
areas.  Waste discharges have put in 7,000-20,000 kg P and 5,000-11,000
kg N per year; surface land runoff has contributed up  to 474 kg P and
610 Kg N; direct precipitation has added  up to 18 Kg P and 24 kg N;  and
ground water inflow has supplied up to 1,552 Kg P and  8,750 kg N
annually.

Thermal stratification usually comes and  goes during summer and early
fall, but has endured continuously for about two months.  When present
the hypolimnion occupies a relatively small volume.  During open water
seasons and most of the time under ice the chemical nature of the major
water mass is of the sort imparted by photosynthesis,  and it rarely
changes during periods with complete circulation.

The lake is mainly fed by surface inflow  (mostly down  the Pelican River)
but ground water has significant contributions (up to  3.10 x 106 m3/yr.).

Weed and fish harvest has not removed more than a fraction of annual N
and P increments.  Complete removal of the biota would eliminate only
part of the annual P load, and significant removal of nutrients from
inflowing water appears the only practicable method to insure lake
recovery.

Profuse weed and phytoplankton populations compete for nutrients; when
harvesting reduced weed populations phytoplankton mass and
photosynthesis increased.  Weed harvest in 1971 and 1972 yielded but
26% and 14%, respectively, of the 1970 crop, and in 1973 weeds in
harvestable locations did not merit harvester operation.

Phytoplankton was generally dominated by  diatoms in spring and fall  and
by blue-green algae in summer.  Green algae were frequently dominant
in winter when total numbers were low. Greatest densities were achieved
by diatoms.  Blue-greens have not attained more than 11% of maxima
reached by diatoms, but have been much more noticeable along shore lines
than diatoms, since they are more prone to drift.  Before harvesting
began macrophytes occupied about 34% of the lake area  (down to 3 m
except for P_. praelongus which grew down  to 6 m).  The fish population
is now dominated by bullheads; the lake was formerly known for its
walleye populations.

Phosphorus loading has varied from 1.52 to 4.16g/m2/yr. and nuisance
conditions have occurred each year regardless of loading rate in this
range.  This suggests that phosphorus is  not limiting above a certain
loading or that further modifications or  factors must  be incorporated in
loading-detention models.
                                 62

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                            DATA SUMMARY
                                FOR
                            LAKE SALLIE
Trophic state
Lake type
Drainage area
Lake surface area
Mean depth
Retention time
Mean alkalinity
Mean conductivity
Mean dissolved phosphorus
Mean total phosphorus
Mean inorgan. nitrogen
Phosphorus loading
   point source
   non-point source
   surface area loading
Nitrogen loading
   point sources
   non-point sources
   surface area loading
Eutrophic
Lake
1,543,600,000
5,300,000
6.35
1.51
162
(280-360)  mean 310
0.130
0.34955
0.4437
7,060 - 20,081
1,030 - 1,972
1.52 - 4.16
5,590 - 11,360
4,195 - 9,086
2.78 - 3.02
(oligo., meso., eutro.)
(lake, impound., estuary)
(square meters)
(square meters)
(meters)
(years)
(mg/1)  (1973-74)
(umhos)  (1973-74)
(mg/1)
(mg/1)
(mg/1)

(kg/year)
(kg/year)
(gr/meter2/year)

(kg/year)
(kg/year)
(gr/meter2/year)
                                     63

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               THREE OLIGOTROPHIC LAKES IN NORTHERN MINNESOTA


                         Stephen J.  Tarapchak


               Great Lakes Environmental Research Laboratory
              National Oceanic and Atmospheric Administration
                            Ann Arbor, Michigan

                                     and


                             Richard F. Wright


                   Norwegian Institute for Water Research
                                Oslo, Norway


                               I.  INTRODUCTION


A.  Past History

The three lakes (Dogfish L., Meander L. and Lamb L.) described in this report
are located in the Superior National Forest near the southern border of the
Boundary Waters Canoe Area in northeastern Minnesota.  The area in the vicin-
ity of the lakes in uninhabited.

The general area consists primarily of virgin deciduous-coniferous forest.
The drainage basin of Dogfish L. has remained virtually undisturbed, and the
only significant disturbance in the watershed of Lamb L. has been the con-
struction of a dirt road bypassing the lake.  The watershed of Meander L. has
been subjected to minor disturbances;  the construction of Echo Trail in 1926,
the building of a CCC Camp in 1934, selective cutting of pines in the north-
western portion of the basin in 1945, and further cutting about 200 m from
shore in the southwestern basin in 1969-1970.

On May 14, 1971, the Little Sioux fire began and in the course of three days
burned 5900 ha.  The fire killed about 70% of the overstory in the watershed
of Meander L. and about 65% of the overstory in the drainage basin of Lamb L.
Dogfish L., similar in water chemistry to Meander L. and located 2 km west of
the fire perimeter, was selected as a "control" lake.

A cooperative effort was undertaken to investigate the effect of the fire on
the watersheds and the lakes.  In addition to the results presented here,
studies on internal nutrient cycling in the watersheds have been conducted
by Dr. H. E. Wright and J. P. Bradbury and J. C. B. Waddington of the Limno-
logical Research Center, University of Minnesota.

                                     64

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Studies on water chemistry and phytoplankton were initiated in May/June
1971 and continued into the winter of 1972/73,  Investigations on the
hydrology and nutrient budgets of the watersheds and lakes were conducted
during the period January 1 - December 31, 1972.  Some of the results have
been published by Wright (1974), Wright (1975), Bradbury et al. (1974), and
Tarapchak (1975).

                       II.   GEOGRAPHIC DESCRIPTION

A.  Latitude and Longitude

The lakes are located in northeastern Minnesota and are within 10 km of
one another (Table 1 contains latitude and longitude).

B.  Altitude of the Lakes

The altitude of the lakes at their surface is approximately 400 m above
sea level (Table 1).

C,  Catchment Area

The catchment areas (Acj) of Lamb L. and Meander L. are small and nearly
equivalent,  A^ of Dogfish L. is about one-third the size of the other lakes
(Table 1).

D.  General Climatic Data

Northern Minnesota has a typical mid-continental climate with cold winters
and warm, moist summers.  Average monthly temperatures and precipitation
records from two weather stations located within 30 km of the lakes are
given in Table 2 (data from the Environmental Science Services Administration,
                                    65

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Table 1.  Geographic location and description and morphometric
          and hydrologic characteristics of the three lakes.

Latitude
Longitude
Altitude Above
Sea Level (m)
Drainage Basin
Area Ad (ha)
Lake Surface
Area A0 (ha)
Total Ad + A0 (ha)
Ratio A(j + A0
Length (m)
maximum
Width (m)
maximum
average
Shore Length
(xlO3 m)
Volume (106 m3)
Depth (m)
maximum
average
Ratio Epilimnion
to Hypolimnion
Retention Time (yrs)
Meander
48°08'N
92°8.5'W

423

133

36
169
2.03

1158

1006
210
3.117
1.80

7.0
5.0

1.55
2.7
Dogfish
48°11.5'N
92°11'W

393

59.1

29.1
88.2
3.70

885

805
117
2.966
1.164

5.5
4.0

—
3.5
Lamb
48°10'N
92°6.5'W

376

156.2

39.7
195.9
3.94

965

708
402
3.318
1.588

5.5
4.0

1.68
2.3
                              66

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Table 2.  A summary of average monthly air temperatures
          and average monthly total precipitation.  First
          row of values from the Wlnton Power Plant; second
          row of values from Crane Lake Ranger Station,
          Minnesota.

January
February
March
April
May
June
July
August
September
October
November
December
Annual Mean
Temp. (°F
1971
- 4.0
- 4.0
10.2
10.7
19.3
20.4
37.8
39.2
48.6
50.6
64.3
65.1
63.2
63.1
63.0
64.9
57.0
57.1
47.0
4b.2
26.2
26.1
11.2
10.9
37.0
37.7
) Preclp.
(inches)
0.61
0.59
1.29
1.31
1.02
0.61
0.88
1.22
2.32
3.11
3.97
3.39
2.29
1.71
2.1«
1.97
4.2d
4.38
4.39
6.65
1.84
2.09
0.8?
0.71
25.9
27.4
Temp. (°F) Precip.
1972 (inches)
- 3.8
- 3.8
3.7
2.4
18.3
18.9
34.8
36.2
57.8
58.5
62.3
62.5
63.8
63.9
64.6
64.7
50.7
52.3
39.6
41.1
25.2
25.8
4.5
4.3
35.1
35.6
1.03
1.18
0.61
0.44
1.34
1.26
1.16
1.25
1.46
0.98
2.07
3.01
6.15
6.47
4.62
2.34
2.34
3.20
l.lb
1.62
0.75
0.52
1.39
0.95
24.0
23.2
                             67

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U.S. Department of Commerce).   Mean annual precipitation is about  25
inches, and annual temperatures average about 36°F.   The lakes are ice-
covered from November through early April.  The prevailing winds are
from the southwest during the .open-water season.  Mean annual evaporation •
just exceeds mean annual precipitation in the region.

E.  General Geologic Characteristics

The lakes lie within the Vermilion granite batholith.
This massive Precambrian intrusion is composed of 25% quartz, 50%
potassium feldspar, 20% oligoclase, and 2% biotite,  and minor amounts of
zircon, allanite, muscovite, and magnetite (Grout 1925).  Granite  outcrops
are visible along ridges and knobs, and intervening  low spots often are
mantled by a thin layer of ground moraine deposited  by the Rainy Lobe of
the Wisconsin ice sheet (Wright and Watts 1969).  The till is a brown sandy
material and is highly permeable.  Thick soils that  occur on the glacial-
lacustrine clays are poorly developed, and acid soils that are poorly-to-
well drained have developed on the sandy ground moraine (Nordin 1974).  The
soils generally are less than 25 cm thick but can range in spots to 2 m.
Granite outcrops are covered by a thin mat of moss and organic matter.
The soils in the drainage basins of Dogfish L. and Meander L. are similar.  Those
in the watershed of Lamb L., however, contain deposits of gray calcareous
clays.

F.  Vegetation

The lakes are located in a mixed deciduous-coniferous forest dominated by
pine, spruce, fir, aspen, and birch (Wright and Watts 1969).  The
watersheds of the three lakes consist primarily of undisturbed virgin forest.
                                   68

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G.  Population (The watersheds are uninhabited)

H.  Land Use (None)

I.  Use of Water CNone)

J.  Sewage and Effluent Discharge (None)
                  III.  DESCRIPTION OF MORPHOMETRIC AND
                         HYDROLOGIC CHARACTERISTICS
A.  Surface Area of Water


The lakes have relatively small surface areas (A0).   A0 of Dogfish L.  is

the smallest of the three lakes.  Meander L.  has the greatest length

and -maximum width, and Lamb L. has the greatest average width and shore

length (Table 1, Fig. 11.


B.  Volume of Water


Bathymetric maps were used to compute lake volume for Meander L.  and Lamb

L. (Fig. 1).  The volume of Dogfish L. was computed  from an estimate of

mean depth (obtained from line soundings) and surface area.  Meander L.

has the largest and Dogfish L. the smallest volume (Table 1).


C.  Maximum and Average Depth


The maximum and average depths of the lakes are similar.  Meander L. has

the greatest maximum depth, and Lamb L. and Dogfish L. are essentially

identical (Table 1, Fig. 1).


D.  Location of Exceptional Depths


Bathymetric maps for Meander L. and Lamb L. (Fig. 1) show that the basins

are steeply sloped near the shore and have gently sloping to flat bottoms

                                    69

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cd
-P
O
w
CD
fi
 CD
-X
 Cd
 cd
 0
 0
 w
 a
 cd
 S

 o
•H
 !H
-P
 cd
 hO

-------
offshore.  Line soundings in Dogfish L. indicate a similar basin




configuration.






E.   Ratio of Epilimnion to Hypolimnion






The ratio volume of the epilimnion/volume of the hypolimnion in Meander




L. and in Lamb L. was computed from bathymetric maps and from the location




of the thermocline in mid-July (3.5 m and 2.5 m in Meander L. and Lamb L.,




respectively).  Ratios of 1.55 and 1.68 (Table 1} for Meander L. and




Lamb L. indicate large euphotic zones relative to volume of bottom waters.







F.   Duration of Stratification






Temperature profiles indicate that permanent summer stratification




is established by mid-June and is disrupted by mid-September.
G.   Nature of Lake Sediment






The nature of the lake sediments and the results of paleolimnologic




analyses are given in Wright (1974) and Bradbury et al. (1974).  A 60-cm




core of surface sediment from Meander L. was analyzed for per cent dry weight;




carbon, nitrogen, hydrogen content; total phosphorus and major cations; and




pollen and diatom distribution.  The major sediment constituents are biopel,




elastics, and biogenic opal.  Historical variations in sediment chemistry,




pollen, and diatom composition have been detected.   They are attributed to




increases in air-born dust resulting from agricultural activities in




northwestern and western Minnesota in the late 1880's and early 1900's and




to recent disturbances in the watersheds themselves Csee I.A.).





                                      71

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II.  Seasonal Variation of Monthly Precipitation






Average monthly precipitation is given in Table 2.   Additional data are




available in Wright CL974).






I.  Inflow and Outflow of Water






A hydrologic budget, including direct measurements  on surface runoff,




stream flow, precipitation falling in the basins, and lake outflows, is




given by Wright (1974).






J.  Water Currents (Not investigated)






K.  Water Renewal Time






Retention time for each lake was computed from estimates of lake volume and




components of the hydrologic budgets.  Dogfish L. has the longest and Lamb




L. has the shortest retention time (Table 1).






                 IV.  LE-mOLOGICAL CHARACTERIZATION SUMMARY






A.  Physical






    1.  Temperature






    The lakes are dimictic,  exhibiting thermal stratification in summer and




    winter.  Spring overturn occurs just after ice-out in mid- or late-April,




    and the lakes stratify in June.  Temperatures of the surface waters in




    summer range between  20° and  23°C; the bottom waters are  at least 10°C in




    each lake during summer.  Pall overturn occurs in September, and the lakes




    stratify inversely after an ice cover develops in November.





                                      72

-------
    2.   Conductivity

    Specific conductance measurements  show that Meander  L.  and Dogfish
    are similar,  but that the waters of  Lamb  L. have much higher  conductivity
    levels (Tables 3-5).

    3.   Light

    Secchi-disc transparency ranges between 1.5 and  4.0  m in  the  lakes, but
    generally tends to be lower in Lamb  L.  (Tables 6-8).

    4.   Color

    Color was not measured directly.   Lamb  L.  is  distinctly yellow-brown
    (difficult to filter 150 ml through  a  0.5 millipore  filter).  The  other
    two lakes are clear to very slightly stained  with  "humics."

    5.   Solar Radiation

    Not investigated.   Measurements  are  available from the  Environmental
    Protection Agency Laboratory,  Shagawa  Lake, Ely, Minnesota.

B.  Chemical

    1.   pH

    Values of pH in the lakes are comparable  (Tables 3^5).

    2.   Dissolved Oxygen

    Oxygen measurements indicate that  the  surface waters of the three  lakes
    are saturated during most seasons  but  that depletion to 1.0-2.0 mg/1  occurs
    in the hypolimnion during late summer.
                                     73

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   3.  Total Phosphorus and Fractions






   Total PO.-P, total soluble PO.-P, and particulate PO.-P (by difference)




   were measured by the phosphomolybdate/stannous chloride method after




   digestion with K_S2Oo-  Average values of total PO.-P for the euphotic




   zone and the water column are given in Tables 9-11 and summarized in




   Tables  6-8.  Total PO -P values generally are higher in Lamb L. than




   in  the  other two lakes.






   4.  Total Nitrogen and Fractions






   Measurements of total nitrogen, NB.N, NO -N and NOo-N are given in




   Tables  3-5,  The concentrations are higher in Lamb L. and Meander L.






   5.  Alkalinity






   Bicarbonate alkalinity values are summarized in Tables 6-8.  Levels




   in  Meander L. and Dogfish L. are similar, but concentrations in




   Lamb L.  are significantly higher.






   6.  Ca, Mg, Na, K, SO,,  Cl






   Concentrations of major  cations generally are similar in Meander L.




   and Dogfish L., but  they are significantly higher in Lamb L.   SO,




    concentrations are lower in Dogfish L.,  and Cl concentrations  appear




   to  be higher in Meander  L.






    7.   Trace Metals  CNot  investigated)






C.  Biological
                                    80

-------
    Table 9.   Average concentrations of  chlorophyll .a and total
              phosphorus in Meander Lake during open  water seasons
              of 1971 and 1972.   Mean values  are given for the
              epilimnion (Xe)  and for the water column (Xc).  Values
              for Xc were not  calculated when measurements for  either
              the epilimnion or hypolimnion were »ot available.

                Chlorophyll a  (ug/1)       Total Phosphorus  (ug/1)

 1971            Xe             Xc             Xe 	      Xc
 1972
5-21
5-28
6-20
7-5
7-21
8-5
8-15
9-3
9-18
10-2
10-16
10-30
4.1
3.2
0.9*
2.8*
—
1.5
4.2
2.8
5.1
2.0
3. 1*
2.8*
4.9
3.6
2.6*
4.7
10.7
2.7
5.6
7.5
5.6
2.0
3.5
3.3
—
—
4.0*
56.0*
—
5.8
5.0*
5.7
6.0*
15.3
8.5*
—
—
—
27.0*
—
—
4.8
7.0*
10.6
6.5
11.9
8.4
—
5-7
5-20
6-3
6-17
7-1
7-15
7-31
8-13
8-20
9-5
9-20
10-7
10-21
1.8*
0.4
—
2.9
1.9
0.6
—
0.4
—
—
—
—
--—
1.5
0.7
—
2.3
2.5
0.7
0.8*
3.8
—
—
—
—
— —
6.0*
9.8
6.6
10.5
8.7
14.2
5.5
10.5
4.0*
7.3
8.5
10.0*
11.1
7.3
9.3
6.5*
18.0
9.2
13.1
7.9
12.4
—
7.7*
8.3
9.5*
8.8
*Indicates that only one measurement was made in the epilimnion or
 hypolimnion.
                                  81

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Table 10.   Average concentrations of chlorophyll a^ and total phosphorus
           in Dogfish Lake during open water seasons of 1971 and 1972.
           Mean values are given for_the epilimnion (Xe)  and for the water
           column (Xc).   Values for Xc were not calculated when
           measurements  for either the epilimnion or hypolimnion were not
           available.

             Chlorophyll a (ug/1)         Total Phosphorus (ug/1)

 1971         Xe             Xc              Xe            Xc
5-27
6-20
7-5
7-21
8-10
8-16
9-4
9-19
10-2
10-16
10-30
—
3.1*
2.1
1.2*
2.4
2.9
—
8.4
6.7
5.8*
5.5
—
3.7*
4.0
12.0*
7.4*
5.2
—
7.1
6.3*
5.3
1.7
10.0*
5.0*
12.0*
5.6
5.8
6.0
11.0
15.3
11.9
8.0*
—
— .
—
13.8*
8.2*
—
7.3*
10.2
12.4
12.1*
9.4
—
 1972
5-5
5-20
6-3
6-17
7-1
7-15
7-31
8-12
8-19
9-5
9-20
10-7
10-22
2.7
2.1
—
2.3
2.1
1.4
2.7
4.4
—
—
—
—

2.7
2.3
—
7.2*
4.1
3.8
—
6.7
—
—
—
—

9.5
9.8
7.3
10.3
8.0
8.0
11.8
9.5
6.0*
9.5
9.8
13.6*
9.6
8.0
10.6
8.9
11.3*
11.4
8.0
9.9
10.0
—
10.3
11.7
11.3
9.9
*Indicates that only one measurement was made in the epilimnion or
 hypolimnion.
                                  82

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 Table 11.  Average concentrations  of  chlorophyll £ and  total phosphorus
            in Lamb Lake during open water  seasons  of  1971  and  1972.  Mean
            values  are given for the epilimnion (Xe) and for the water
            column  (Xc).  Values for Xc were not calculated when measurements
            for either the  epilimnion  or  hypolimnion were not available.

              Chlorophyll a (ug/1)          Total Phosphorus (ug/1)
  1971         Xe            Xc             Xe            Xc
5-20
5-28
6-5
6-20
7-5
7-21
8-4
8-15
9-5
9-18
10-2
10-17
10-31
—
3.5
—
1.5*
3.0*
—
2.3
2.4
6.9
6.3
6.7
7.0
11.9
—
5.1*
—
4.8*
3.9
1.8
3.4
5.2
7.4
4.6
6.9
6.7
11.2*
10.0*
—
25.0*
25.0*
17.5*
—
8.0
8.5
11.8
12.0
17.5
7.0
—
—
—
—
—
—
7.5
10.4
20.0
11.8
13.0
15.9*
7.3*
—
  1972
5-5
5-22
6-3
6-18
7-2
7-15
7-31
8-12
8-20
9-6
9-21
10-8
10-21
2.0
4.4*
—
4.2
1.2
1.4
2.3
3.0
—
—
—
—
— —
1.5
—
—
4.6
2.3
—
—
3.1
—
—
—
—
— —
11.5
8.0*
8.5
10.5
13.8
12.0
14.0
—
12.0*
13.2
15.0*
9.3
11.5
10.8
— •
17.0
8.3
11.9
14.1*
—
13.5
—
12.4
12.8
8.3*
12.3
^Indicates that only one measurement was made in the epilimnion or
 hypolimnion.
                                   83

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1.  Phytoplankton






    a.  Chlorophyll a_






    Chlorophyll a_ was measured spectrophotometrically CStrickland




    and Parsons 1968) until May 1972 and with a fluorometer there-




    after.  The latter values, corrected for phaeophytin, are suspect




    because of time delays in analysis.  Average values of chlorophyll




    a_ for the euphotic zone and the water column are given in Tables




    9-11 and summarized in Tables 6-8.  Although there are marked




    seasonal differences among the lakes, the mean values for each of




    the lakes are roughly comparable.






    b.  Primary Production  CNot investigated)






    c.  Algal Assays  (Not investigated)






    d.  Identification and Count






    Phytoplankton samples were analyzed by the Utermohl  (1958) technique.




    Approximately 400 taxa were identified to species.  The counts,




    expressed as biomass estimates, indicate that standing crop levels




    in Dogfish L. and Meander L. are comparable but they are significantly




    higher in Lamb L.  Further information on seasonal cycles is available




    in Bradbury et al. (1974) and Tarapchak  (1975).






2,  Zooplankton (Not  investigated)






3.  Bottom Fauna CNot investigated)






4.  Fish  CNot investigated)




                                 84

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    5.  Bacteria CNot investigated)






    6.  Bottom Flora






    There is abundant diatom growth on the littoral sediments (cf.  Bradbury




    et al. 1974).






    7.  Macrophytes






    Not investigated extensively.  Visual observations indicate Sparse




    development in the lakes.






                            V.  NUTRIENT BUDGETS SUMMARY







The details of nutrient budgets for major cations and total phosphorus in




1972 are available in Wright (1974, 1975) and Bradbury et al. (1974).  Direct




measurements were made on inputs from the atmosphere, from streams, and from




overland flow.  Quantities of nutrients leaving the lakes via stream outflow




were measured and permit calculations of the amounts retained in the lakes.




In order to determine the increase in nutrient loadings due to the fire,




nutrient export from the watershed of Dogfish L. (the control lake) was




considered to be representative of nutrient export from the watersheds of




Lamb L. and Meander L. prior to the fire.






A.  Phosphorus






The total input of phosphorus to the lakes and specific surface loadings are




given in Table 12.  Lamb L. has the highest specific loadings and Dogfish L.




the lowest.  Atmospheric loading is a major source of phosphorus for each




of the lakes.  Using the measured quantity of phosphorus export from the






                                     85

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   Table 12.  A summary of phosphorus loading rate computations used to
              predict the trophic state of Lakes Dogfish,  Meander,  and
              Lamb for 1972.
                                Dogfish L.
              Meander L.
                Lamb L.
Total Phosphorus
  Loading (kgm)

Specific Surface
  Loading of      „
  Phosphorus (mg/m /yr)

    Runoff Input
    Precipitation Input
    Total

Per Cent Phosphorus
  Loading Retained in
  the Lake

Vollenweider's (1968)
  Trophic Limits
  (mg/m2/yr)

    Admissible

    Dangerous

Ratio of Actual
  Specific Surface
  Loading of Phosphorus
  to Vollenweider's
  (1968) Trophic
  Limits

    Admissible

    Dangerous

Specific Surface Loading
  (gm/m^/yr) divided by
  mean depth (m)/Retention
  time (yrs.), from
  Vollenweider 1973
  4.888
  3.1
 13.7
 16.8
 74
 57.5

114.8
  0.29

  0.15
  9.936
 13.2
 14.4
 27.6
 72
 66.1

131.8
  0.42

  0.21
 12.14
 16.6
 14.0
 30.6
 71
 57.5

114.8
  0.53

  0.27
  0.015
  0.015
  0.018
                                     86

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watershed of Dogfish L. as the supply from a natural, undisturbed system,

the fire apparently increased the loadings to Meander L. and Dogfish L. by
38 and 53 per cent, respectively.  Phosphorus retention in the lakes is high
and ranges between 71 and 74 per cent.

B.  Nitrogen (Not investigated)

C.  Other Nutrient Budgets

Major cation loadings are given in Table 13.  The fire increased potassium

export from the burned watersheds.  Loadings of other cations ..to the lakes,
however, apparently were not increased by the fire.

                              VI.  DISCUSSION

A., B.  Limnological Characteristics and Delineation of Trophic State

The three lakes (with the possible exception of Lamb L.) are similar to
other undisturbed wilderness lakes located on the Precambrium Shield in
northeastern Minnesota (Tarapchak 1973), and generally can be considered
members of the same population of lakes located in the Experimental Lakes
Region CELA) in northwestern Ontario, Canada.  The lakes are low in salinity,
with concentrations and ionic proportions of major anions and cations that
are similar to those reported for representative ELA lakes by Armstrong
and Schindler (1971).   On the basis of the trophic scale for north-temperate
lakes presented by Tollenweider 0-968}, the annual average biomass of
phytoplankton would rank Dogfish L. and Meander L. in an oligotrophic-mesotrophic

lake grouping (1.5-5.0 mg/1).  Lamb L., however, would be considered eutrophic.

Chlorophyll a and total phosphorus concentrations would place Dogfish L.
and Lamb L. either in an oligotrophic or mesotrophic category; Lamb L,
                                   87

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  Table 13.  A summary of calcium, magnesium,  potassium,  and sodium loading
             rates for Lakes Dogfish, Meander, and Lamb for 1972.   Symbols
             Runoff Input Mr, Precipitation Input Mp,  Total (Mr + Mp).   All
             values are mg/m^ of lake surface.
                                Dogfish	Meander	Lamb
Calcium

  Mr                              370             1090              6168
  Mp                              207              223.4             222
  Total                           577             1313.4            6390

Magnesium

  Mr                              162              450              1830
  Mp                               29.5             33.5              32.8
  Total                           191.5            483.5            1862.8

Potassium

  Mr                               42.2            600               561
  Mp                               48               49.4              49.3
  Total                            90.2            649.4             610.3

Sodium

  Mr                              222              556              1745
  Mp                               58.5            53.4               59.3
  Total                           280.5           609.4             1804.3
                                     88

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would be ranked as a eutrophic lake.


C.  Trophic State vs. Nutrient Budgets


Each of the three lakes receive tolerable phosphorus loadings using

Vollenweider's (1968) original relationship between the specific

surface loading and mean depth z of a lake.  The measured loadings for

each of the three lakes are in fact well below "admissible" levels (Table

12).


A recent model proposed by Vollenweider incorporates flushing time to

improve the expected relationship between phosphorus loading and lake

response (cf. Vollenweider 1973 and Vollenweider and Dillon 1974).  The

expression specific loading divided by z/detention time was computed for

the lakes.   These computations place each lake well below "admissible"

phosphorus loadings, and suggest that the lakes are subjected to loadings

that can be tolerated by their existing morphometry and hydrology.


                             VII.  SUMMARY


An investigation on water chemistry and phytoplankton, coupled with

studies on nutrient budgets and hydrology of three wilderness lakes in

northeastern Minnesota, was undertaken to assess the effects of

terrestrial nutrient release on wilderness lakes on the Precambrian Shield.

The lakes are similar chemically and biologically to other lakes in

northeastern Minnesota and appear to be members of the same population

of lakes in northwestern Ontario.  Phosphorus export from the watersheds

of two lakes increased substantially after the fire.  The loadings, however,

were not high enough to drive the lakes from oligotrophy into a state of

mesotrophy as judged by Vollenweider's nutrient loading/trophic state model.
                                     89

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                                REFERENCES

 Armstrong, F.  A.  J., andD.  W.  Schindler.   1971.   Preliminary  chemi-'
      cal characterization of waters in the Experimental Lakes  Area,
      northwestern Ontario.  J.  Fish.  Res.  Bd.  Canada 28:  171-188.

 Bradbury, J. P.,  S.  J.  Tarapchak,  J.  C.  B.  Waddington, and R.  F. Wright.
      1974.  The impact  of a  forest fire on a wilderness lake in northeastern
      Minnesota.   Submitted for  publication in  the  Proceedings  of the 19th
      SIL Congress.

 Grout, F. F.  1925.   The Vermilion batholith of Minnesota.  J. of Geology
      33: 467-487.

 Nordin, J.  1974.   Characterization and mapping of the soils and vegetation
      of the Little Sioux fire,  northeastern Minnesota.  "Univ. Minnesota,
      M.S. Thesis  (in preparation).

 Strickland, J. D.  H., and T.  R.  Parsons.  1968.  A practical handbook of
      seawater analysis.   Bull.  Fish.  Res.  Bd.  Can.   167.  311  p.

 Tarapchak, S.  J.   1973.   Studies on phytoplankton  distribution and
      indicators  of trophic state in Minnesota  lakes.  Unpublished Ph.D.
      Thesis.  Univ.  Minnesota.   390 p.

 Tarapchak, S.  J.   1975.   The effects  of  a  forest fire on  the water chemistry
      and phytoplankton  of three oligotrophic lakes in northeastern Minnesota.
      In manus cr ip t.

 Utermohl, H.  1958.   Improvements  in "the quantitative methods  of phytoplankton
      study.  Intern. Ver. Theoret. Angew.  Limnol.,  Verhandl. Comm. 9.  27p.

 Vollenweider,  R. A.   1968.  Scientific fundamentals of the eutrophication of
      lakes and flowing waters,  with particular reference  to nitrogen and
      phosphorus  as factors in eutrophication.  Organ. Econ. Coop. Div. (Paris)
      Tech. Rep. DAS/CSI/68.   27.   p.  182.

 Vollenweider,  R. A.   1973.  Input-output models.   Schweiz. Z.  Hydrol.  In
      press.

 Vollenweider,  R. A., and P.  J.  Dillon.   1974.  The application of the
      phosphorus  loading  concept to eutrophication  research.  Publication
      No. NRCC  13690  of  the Environmental Secretariat, National Research
      Council of  Canada.

 Wright, E. E., Jr.,  and  W. A. Watts.   1969.  Glacial and  vegetational history
      of northeastern Minnesota.  Minnesota Geological Survey Special
      Publication No. SP-11.   59 p.

 Wright, R. F.  1974. Forest  fire: Impact  on  the  hydrology, chemistry, and
      sediments of  small  lakes in northeastern Minnesota.  Interim Report No.
      10, Limnological Research  Center, University  of Minnesota.

Wright, F. R.  1975^  Forest  fire:   Impact  on the hydrology, chemistry, and
     sediments of small  lakes in northeastern Minnesota.   Submitted for
     publication.

                                     90

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              PHYTOPLANKTON, PHOSPHORUS, AND SEWAGE EFFLUENTS

                             IN LAKE MINNETONKA


                              Robert 0. Megard
               Department of Ecology and Behavioral Biology
                          University of Minnesota
                            St. Paul, Minnesota
                                INTRODUCTION
Lake Minnetonka occupies a group of basins in eastern Minnesota, near
Minneapolis.  The city of Minneapolis developed after the middle of the 19th
century at St. Anthony Falls on the Mississippi River, the region became acces-
sible by railroads after 1870, and Lake Minnetonka began to attract tourists
from throughout the United States.  The lake became an important vacation area,
with several large hotels, elegant summer homes, and commercial steamboat
service for transportation across the lake.

The villages near the lake have become residential suburbs of Minneapolis
since 1950, and most residences are now occupied permanently.  The population
in the watershed was about 10,000 in 1930, and it increased at the rate of 4S
per year to 46,000 in 1970.  The villages began to construct secondary sewage
treatment plants in 1927.  By 1963, effluents from six municipal treatment
plants were entering the lake and its tributaries.  The quality of water in
the lake decreased as the population increased.  The minimum secchi-disc
transparency of Lower Lake Minnetonka, the largest basin, decreased from
2.5 m in 1937 to only 0.9 m in 1969, and maximum population densities of
planktonic algae increased about four-fold.

Sewage effluents have now been diverted from the lake in an effort to decrease
algal abundance.  Effluents were diverted from Lower Lake Minnetonka, the
largest basin, during the summer of 1971-1972.  Concentrations of phosphorus
and population densities of planktonic algae in this basin have both decreased
since diversion.  Most of the phosphorus that was lost must have been deposi-
ted in the sediments, because losses through the outlet stream are trivial.
                                    91

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                               GEOGRAPHY
Lake Minnetonka is a complex of lake basins with a total surface area
          9        9
of 58.6 km  (22 mi. ) located in east-central Minnesota (44° 55' N
                                                                   2
lat, 93° 37' W long) (Fig. 1).   The area of the watershed is 312 km
        f\
(123 mi. ), which includes marshes and other lakes with an area of
     99                                     22
48 km   (18.9 mi. ), and uplands with an area of 212 km  (82.6 mi ).
                                       2
Thus the total catchment area is 371 km .  The water level is con-
trolled by a small dam at the outlet (Minnehaha Creek), which has a
crest of 283 m (929 ft.) above sea level.
      X* A
     YV>*
 Figure 1.   Map of Lake Minnetonka.   The localities studied most
 intensively are Browns Bay in the Lower Lake, Carman Bay in the Upper
 Lake, and Halsted Bay.

Climatic, hydrologic, and geographic data about the lake and its
                                                    123
watershed have been compiled in engineering reports. '  '    The mean
annual temperature between 1891 and 1966 was 7.8° C (45° F).  The
minimum temperature in winter was -38° C (-37° F), and the maximum
in summer was 44° C (112° F).  Average air temperatures are below
0° C  (32° F) for five months and below -7° C  (20° F) for three months
each year.  Ice covers the lake approximately five months each year,
from December to April.
                                    92

-------
The average precipitation during the period from 1915 to 1968 was
73 cm/yr  (28.9 in./yr).  Average evaporation from a free water sur-
face is 76 cm/yr  (30.0 in./yr).  Precipitation is highest, 10 cm
(4.1 in.) during June and lowest, 2 cm  (0.76 in.), during January.
Mean annual snowfall is 144 cm  (55.8 in.).   The driest year was 1958,
with 41 cm (16.2 in.) of precipitation, and the wettest was 1965,
with 101  cm (40 in.).
The lake  occupies basins that were occupied by blocks of glacial
                                    4
ice buried in the St. Croix Moraine.   The moraine is composed of a
young, gray, calcareous drift and an older, red, non-calcareous drift.
The red drift was deposited on Lower Paleozoic rocks by a glacial
lobe that came from the basin of Lake Superior, 240 km (150 mi.)
northeast of Lake Minnetonka.   The gray drift was deposited by a glacial
lobe that came from the west,  moved across the red drift into western
Wisconsin, and began to melt about 14,000 years ago.    The oldest
lake sediments in a lake located in the gray drift 15 km southwest of
Lake Minnetonka,  contain wood that is 12,000 ± 160 radiocarbon years
old,  indicating that melting ice blocks may have remained buried in
the moraine 2,000 years after the glacier disintegrated.
The glacial drift includes 40-100 m of alternating gravels, sands,
and clays.  One of the Paleozoic formations beneath the drift, the
Jordan Sandstone,  is an artesian aquifer.   It receives water from
Lake Minnetonka,  and it is an important source of ground water for
metropolitan Minneapolis.
The landscape near Lake Minnetonka is hilly, with maximum elevations
of 330 m  (880 ft.), or 47 m above the lake.  A mixed deciduous fotest
composed of Ulmus americana (American elm), Tilia americana (bass-
wood) , Acer saccharum (sugar maple), and Quercus ellipsoidalis (pin
oak) occurred in the region until the time of european settlement,
which began during the middle of the 19th century.
The woodlands were replaced initially by small dairy farms and
market farms,  but agriculture is now relatively unimportant; only
     2        2
42 km  (16 mi. )  or 15% of the watershed is now agricultural.  The
                                                           2
area of urban land in the watershed in 1970 was about 52 km , which
is about  30% of the land that would be suitable for residential or
                                     93

-------
commercial use.  The average population density on urban land in
                                      2           23
the watershed was about 700 persons/km  (1,800/mi. ) in 1970.
The lake's shoreline, about 175 km (110 mi.) long, is now almost
entirely occupied by permanent housing.  The lake has been a major
incentive for urbanization.  The average value of land with lakeshore
frontage is approximately ten times greater than the value of land
one mile (1.6 km) from the lake.  There was 23 rental and mooring
facilities for pleasure boats on the lake in 1969, serving about 2,500
boats.  About 27,000 kg (60,000 Ib.)  of rough fish and about 91,000
kg (200,000 Ib.)  of game fish are caught each year by fishermen, a
yield of 20 kg/ha.   About 1,500 temporary shelters are erected on the
ice by fishermen during some winters.
        »
Effluents from six municipal sewage treatment plants, which served
about 20,000 persons or almost one-half the population in the water-
shed, contributed 21% of the water, 32% of the total nitrogen, and
81% of the total phosphorus that entered the lake from tributaries
in 1966-1967.   All villages in the watershed will close their sewage
treatment installations during this decade and join a sanitary district
that operates a large installation on the Minnesota River,  15 km
south of the lake.   Two villages that discharged effluents  into Lower
Lake Minnetonka joined the sanitary district in 1972, thereby re-
ducing the annual phosphorus influx to the largest basin almost 80%.

                       MORPHOMETRY AND HYDROLOGY

Areas, volumes, and depths of the basins of Lake Minnetonka are
compiled in Table 1.  The basins are connected with each other by
natural and artificial navigation  channels.  The Lower Lake contains
                          6  3
54% of the water (216 x 10  m ).  The maximum depth of the Lower Lake
is 27.8 m, and the mean depth is 8.3 m.  The Upper Lake contains
                          fi  o
29% of the water (115 x 10  m ); its maximum depth  (25.6 m) and mean
depth (6.7 m) are both less than those of the Lower Lake.  The  total
volume of the other basins is only 17% of the total lake volume, but
their combined area is 26% of  the total.  The greatest depth,  31 m,
is in Crystal Bay, but the maximum depth of Crystal Bay indicated on
the map used for these computations is only 24 m.
The largest tributary streams,  Sixmile Creek and Painter Creek, both
drain agricultural regions and  flow through marshes and lakes before
                                     94

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               Table 1.  MOKPHOMETRY OF LAKE MINNETONKA

Data derived from a map prepared by the State of Minnesota Department
of Natural Resources.
Basin
Lower Lake

Upper Lake
Crystal Bay
Grays Bay
Maxwell Bay
Stubbs Bay
North Arm
West Arm
Jennings Bay
Forest Lake
Harrison Bay
Hals ted Bay
Black Lake
Seton Lake
Total
Area
Volume
% of ;
106 m2 total 106 m3
26.19 45.0 i 216.20
1
17.32
3.36
0.76
1.20
0.80
1.32
2.32
1.20
0,34
1.02
2.20
0.30
0.16
58.58
29.5
5.7
1.3
2.0
1.4
2.3
4.0
2.0
0.6
1.7
3.8
0.5
0.3

114.83
28.55
2.10
5.20
3.30
5.81
8.98
3.05
1.45
2.43
8.63
0.85
0.33
401.73
% of
total
53.9

28.6
7.1
0.5
1.3
0.8
1.5
2.2
0.8
0.4
0.6
2.1
0.2
0.1

Depth, m
max
27.8

25.6
23.8
6.1
9.5
11.6
14.0
9.8
6.7
12.5
9.5
10.1
7.V6
7.0

mean
8.3

6.7
8.5
2.8
4.3
4.1
4.3
3.9
2.5
4.2
2.4
3.9
2.8
2.1

                                     95

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 they enter western basins of Lake Minnetonka.  The outlet stream
 is  Minnehaha Creek, which flows  eastward  through south Minneapolis
 until it enters  the Mississippi  River,  30 km from Lake Minnetonka.
 The hydrologic balance for  Lake  Minnetonka between 1914  and 1968
 was computed in  terms  of annual  additions and losses  of  water  to
                                    3
 a unit of lake surface, as  follows:
      Additions                                                cm/yr
         direct precipitation                                     73
         tributaries and overland flow                           33
                            Total Additions                           106
      Losses
         evaporation                                              76
         leakage  to aquifer                                       10
         outflowing stream                                       20
                            Total Losses                              106
If the mean depth of the lake is 690 cm, then 15.4% (106 cm yr
* 690 cm x 100) of the water in the lake enters each year.  Eleven
percent of the lake's volume is lost by evaporation each year,
1.4% is lost to aquifers, and 2.9% is lost to the outlet.   If the
retention time for water is defined as the ratio of the mean depth
to the total annual influx (or losses) to a unit of area,  then the
detention time is 6.3 yr (690 * 106 cm yr  ).
Water normally flows over the crest of the dam at the outlet during
the spring and early summer, but there was no overflow during 12
years of drought between 1930 and 1942.  The surface fell to 1.8 m
below the crest of the dam by 1937, exposing 18% of the lake bottom.
In some areas the shoreline receded 300 m.
                                    96

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                               LIMNOLOGY

TEMPERATURE
Temperatures and the duration of thermal stratification depend upon
the areas and depths of the basins.  The variability is indicated
by the difference between the Lower Lake, a large, deep basin, and
Halsted Bay, a small, shallow basin, which have been studied most
intensively (Fig. 2).
The ice usually melts in early or mid-April, and temperatures increase
until they reach 8-10° C at all depths in mid-May; when the water
becomes thermally stratified.  Maximum temperatures of 24-26° C
are achieved in July and August.  The shallow basins become isothermal
again in September, and the large basins in late October.
LIGHT
Coefficients for the attenuation of photosynthetically active radiation
(PhAR) by phytoplankton and by the water have been computed from
the photosynthetic rates of phytoplankton incubated in situ in the
                              o
Lower Lake and in Halsted Bay.   If phytoplankton are distributed
uniformly in the mixed layer, then the daily integral photosynthetic
                             8  9  10
rate is given by the equation '  '

                    TT = In  (I /I ,) p    /(e c + e  ),
                             o  z    max    c     w '

                                                   -2    -1
where ir = daily integral photosynthetic rate, g C m   day
     I  = average irradiance at the surface
    I  t = average irradiance at a depth  z'
     Z
     e  = coefficient for attenuation of PhAR by water and substances
          other than phytoplankton in the water, m
     e  = coefficient for attenuation of PhAR by phytoplankton, re-
      C                             2-1
          ferred to chlorophyll ja, m  mg Chi
                                           2        i
      c = concentration of chlorophyll a, m  mg Chi
   Pmax = volumetric Photosynthetic fate at the average depth where
          PhAR is saturating, g C m   day"
                                    97

-------
                       _TP
                        DIP
                              10
                                      .100
                                                150
 /

•10
                       DIP  '   *
                       .   10   10'
                    E -
                                                   _3

Figure 2.  Distribution of chlorophyll  a_ (mg Chi m  ),  dissolved

                              -3                             -3
inorganic phosphorus (mg DIP m  ),  total phosphorus (mg TP m  ),

                        _2

dissolved oxygen (g 0_ m  ) and temperatures (°  C) at Browns Bay


in Lower Lake Minnetonka (upper panels)  and at Halsted Bay (lower


panels) during 1973.
                                    98

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     The  total coefficient for the attenuation of PhAE  e = e  + e c.
                                                             w    c
     Equation  (1) may be rearranged as an equation for a straight line of
     the  form  y = bx + a:
                         In  (I /I ,)  p    /IT = e c +
                              o  z   max      c
                                                     w
    The  coefficients  e   and  e   were evaluated by (1)  measuring
                      c      w                               6
    ir, and  c periodically,  (2)  computing e  = In (I  /I .)  p   /IT for
                                                  o  z     max
    each measurement, and  (3)  plotting  e against concentrations of
    chlorophyll.  The resulting curve is a  straight line  with a slope
    e  that intercepts the ordinate at  e  (Fig.  3).   The  coefficients
    were evaluated  from  the  equation for the regression of e  On  c
            J i.   ,              8
    computed by  least squares.
                                        (2)
            •o
            c
               c •••
                   I  I  I I  I  I  I I  I   I
                   I I  I  L I  I  I  I I  I  \\
                         50
100
     200
mg CH L m
                                               -3
                                                     300
                           400
Figure 3.  Relationships between the coefficient for" the attenuation of
photosynthetically active radiation (e), the thickness of the euphotic
zone (z ), the quantity of chlorophyll a in the euphotic zone (c ), and
       e                                                        e
concentrations of chlorophyll a. in Lower Lake Minnetonka.  Phytoplankton
attenuate 50% and 90% of subsurface PhAR at the concentrations c' and
9 c' (from Megard et. al. 1975).
                                        99

-------
                                                     2       -1
The estimate of e  in the Lower Lake (0.018 + 0.008 m  tag Chi  )
during 1968 and 1969 is similar to the estimate of e  in Halsted
                    2-1                      c
Bay (0.018 ± 0.009 m  mg Chi  ) during 1973 and 1974, in Windermere,
        11                            12
England,   and in Lake George, Uganda.     However, the value of
e  (0.74 ± 0.20 m  ) in the Lower Lake is significantly lower
 W                                            -1
(P < 0.05) than the value of e  (1.40 ± 0.38 m  ) in Halsted Bay.
The thickness of the euphotic zone and the quantity of chlorophyll
in the euphotic zone may be computed as functions of concentrations
of chlorophyll from the values of e  and e .  If the base of the euphotic
zone is the depth z  at which irradiance I  is reduced to 1% of the
              r    e                      e
irradiance I  at the surface, then
            o
                     1=1  exp - z  (e  + e c).                    (3)
                      eo^ewc
Therefore,
                      ze=-ln (Ie/Io)/Cew+ecc)                    (4)
If chlorophyll is dispersed uniformly, then the quantity in the
euphotic zone c  = c z ,  so that
                         c  = 4.6 c/(e  + e c)                        (5)
                          e           we
Concentrations of chlorophyll a. in Lower Lake Minnetonka ranged from
            _3
3 to 55 mg m   during 1968 and 1969.   The coefficient for the attenua-
tion of PhAR therefore ranged from 0.8 to 1.5 m  ,  the thickness of
the euphotic zone ranged from 6 to 2.5 m, and the quantity of chloro-
                                                           —2
phyll a_ in the euphotic zone ranged from 10 to 130 mg Chi m   (Fig. 3) .
The secchi-disc transparency of Lake Minnetonka depends upon concentra-
tions of chlorophyll a. (Fig. 4), decreasing from 3.5 m to 0.5 m as
                                                        _3
concentrations of chlorophyll increase from 5 to 80 mg m
The minimum transparency in the Lower Lake was 0.9 m during 1969,
                                                 -3
when the concentration of chlorophyll was 43 mg m  .   However, the
minimum transparency increased to 1.2 m and the maximum concentration
                                   _3
of chlorophyll decreased to 30 mg m   in 1974, two years after the
phosphorus influx decreased.
                                   100

-------
•»

o
LJJ
5 3
0.
0)

-------
CHEMISTRY
                                                      -1
The total salinity of Lake Minnetonka is 6.5 meq liter  ,  and the specific
conductance is 317 pmho at 25° C (Table 2).   Calcium (1.35 meq liter"1)
and magnesium (1.32 meq liter  ) are the dominant cations, and bicarbon-
ate (2.5 meq liter  ) is the dominant anion.  The chemistry of water
in Lake Minnetonka is similar to the average for other lakes in the
region, except that concentrations of Na and Cl are somewhat high,
possibly because large quantities of salt are applied to roads near
the lake to melt snow and ice during winter.  Alkalinity ranges
from 2.1 to 2.9 meq liter  , pH from 7.5 to  8.8, and dissolved inorganic
carbon from 28 to 34 mg liter   in the mixed layers of the Lower Lake
and Halsted Bay (Table 3).
                Table 2.  CONCENTRATIONS OF MAJOR IONS
Data for Lake Minnetonka from State of Minnesota Department of Natural
                                          21
Resources and for other lakes from Bright.


Ion
Ca
Mg
Na
K
E cations
HC03
co3
SO.
4
Cl
£ anions
Z salinity

Minnetonka
mg liter
27
16
10
5.8
58.8
153
0
9.8
20
182.8
341.6
-1
meq liter
1.35
1.32
0.44
0.15
3.25
2.51
0
0.20
0.56
3.28
6.53
Average for other
lakes in deciduous
forest in Minnesota
meq liter
1.48
1.71
0.15
0.17
3.51
2.66

0.39
0.09
3.14
6.65
Spec. Conductance:  317 ymho @ 25° C
                                   102

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   Table 3.   ALKALINITY (TA), pH, AND DISSOLVED INORGANIC CARBON (DIG)
           IN THE MIXED LAYER OF LOWER LAKE MINNETONKA AND OF
                         HALSTED BAY DURING 1972
Date
May 4
Jun 1
8
15
Jul 5
18
Aug 10
27
Sep 8
23
LOWER LAKE
TAa
2.6
2.6

2.6
2.4
2.4
2.5
2.1

2.4
PH
8.3
8.5

8.8
8.2


8.2

8.1
DICb
2.6
2.6

2.5
2.4


2.1

2.4
HALSTED BAY
TA

2.8
2.8
2.9
2.5


2.2
2.4
2.5
pH

8.1
8.6
8.7
8.4


7.4
7.8
8.2
DIG

2.8
2.8
2.8
2.5


2.3
2.5
2.5
   a         —1
    meq liter
   •L          _n
    mMol liter
 The  distribution  of  dissolved oxygen,  total phosphorus,  dissolved
 phosphorus, and chlorophyll a. during 1973 at Browns Bay  in  the Lower
 Lake and at Halsted  Bay are shown  in Fig. 2.  Although the  meafi depth
 of the Lower Lake  (8.3 m)  is twice that of Halsted Bay (3.9 m),
 the basins are similar in  that dissolved oxygen disappears  from the
 deep water of both during  July; dissolved inorganic phosphorus is 5-10
    -3                                          -•}
 mg m   in surface water, and may exceed 150 mg m   in deep  water.
 However, concentrations of total phosphorus and of chlorophyll a_
 are both higher in Halsted Bay than in the Lower Lake.   The mean
 (± 95% confidence limits)  concentration of total phosphorus during
 1973 was 88 ± 7 mg m~  in Halsted  Bay and 40 ± 4 mg m~3  in  the Lower
 Lake, whereas the mean concentration of chlorophyll a_ was 37 ± 8
    _3                                o
mg m   in Halsted Bay and 14 ± 4 mg m   in Browns Bay (Table 4).
                                    103

-------
Concentrations of total phosphorus and of chlorophyll a. have both decreased
in the Lower Lake since sewage effluents were diverted (Table 4, Fig. 5).
The mean concentration of phosphorus during about 80% of the ice-free
    son
    -3
                            -3                  -3
season decreased 10 ± 7 mg m  ,  from 50 ± 6 mg m   in 1969 to 40 ± 4
mg m    in 1973, whereas the mean concentration of chlorophyll  decreased
          -3                  -3                       -3
8 ± 6 mg m  , from 22 ± 5 mg m   in 1969 to 14 ± 4 mg m   in 1973.
        Table 4.   CHLOROPHYLL  a AND  PHOSPHORUS  IN LAKE MINNETONKA

                                                    _o
 Mean (± 95% confidence limits) concentrations  (mg m )  in  the mixed
 layer (0-5  m in  Lower Lake, 0-3 m in Halsted Bay).  Number of samples
 in parentheses.
Basin


Lower Lake



Halsted Bay
Year


22 Apr - 7 Oct, 1969
24 Apr - 18 Oct, 1973
23 May - 13 Sep, 1973
18 May - 17 Sep, 1974
24 Apr - 18 Oct, 1973
Chlorophyll


22+5 (21)
14 ± 4 (26)
13 ± 3 (18)
19 ± 3 (22)
37 ± 8 (26)
Phosphorus
Dissolved
Inorganic

8 ± 3


9 ± 4

Total
50 ± 6 (21)
40 ± 4 (28)
36 ± 3 (20)
35+3 (20)
88 ± 7 (28)
There is a high correlation between chlorophyll and total phosphorus
                                                                  14
in Lake Minnetonka during summer but not during spring and autumn,
and it is therefore notable that chlorophyll has decreased in the Lower
Lake only during the summer.  The mean (± 95% confidence limits)
concentration of chlorophyll in the mixed layer between 10 July and
10 September has decreased from 37 ± 3 mg m~  in 1968 and 1969 to
17 ± 4 mg m~3 in 1973 and 1974 at the rate of 1.0 ± 0.3 mg Chl/mg P
                                                       _2
as mean phosphorus decreased from 48 ± 7 to 34 ± 4 mg m   (Fig. 6,
Table 5).  The percentage of the variance of chlorophyll attributable
to its regression on total phosphorus (P %) was 62% in 1968-1969
                                   104

-------
     CO
      I
       Ol
       E
      0.
       0)
Figure 5.  Mean concentrations of chlorophyll _a and of total phosphorus
in Lower Lake Minnetonka in 1969, before diversion of sewage effluents
and in 1973 and 1974, after diversion.  Each point for 1969 is the mean
concentration of samples from the surface at three localities (Browns
Bay, Wayzata Bay, and Gale Island).  Each point for 1973 is the mean
of concentrations at depths of 0 m and 5 m in the mixed layer at Browns
Bay.  (See also Table 4).
 and 53% during all ^our summers.  However the regression of chlorophyll
 on phosphorus was not significant (P > 0.05) during the summers of
 1973 and 1974, indicating that population densities of phytoplankton
 in Lower Lake Minnetonka are now independent of phosphorus concentrations.
 RATES OF PHOTOSYNTHESIS
 Volumetric photosynthetic rates at saturating light  (p
) depend
                                                       max
 upon population densities  (c) and specific photosynthetic rates at
 saturating light  (p   ) according to the equation
                    tnsx
                             p    = c P
                              max      max
 Values of P    were computed from the slope of the equation for the
            max                                             o
 linear regression of p     on concentrations of chlorophyll.   The
            (6)
 high linear correlation between p    and chlorophyll at 6-16° C
                                  max
 (r = 0.84) and at 18-25° C  (r = 0.93) over the range of concentrations
                                     105

-------
               50
            I
            O
            O)
            E
                       i     I     r
                      • 1968-69
                      O 1973 -74
                                         _L
                  0                      50
                                mg  P   m~3
Figure 6.  Relationships between concentrations of chlorophyll a_
'and of total phosphorus in the mixed layer (0 m and 5 m) of Lower
Lake Minnetonka between July 10 and September 10 of 1968 and 1969
(closed circles) and of 1973 and 1974 (open circles).  Regression
statistics are summarized in Table 5.

    Table 5.   RELATIONSHIP BETWEEN CONCENTRATIONS OF CHLOROPHYLL a
                        AND OF TOTAL- PHOSPHORUS
                                                   _3
Mean (± 95% confidence limits)  concentrations (mg m  )  of total
phosphorus (TP) and of chlorophyll a_ (Chi),  and the slope (b)  of
the equation (y = bx 4- a)  for the linear regression of  chlorophyll
on total       phosphorus   in the mixed layer of Lower  Lake Minnetonka
during summer (July 10 - September 10)  before (1968-1969) and  after
(1973-1974) diversion of sewage effluents.   Also indicated are the
proportion (P %)  of the variance of chlorophyll attributable to its
regression on phosphorus,  the significance  of the regression
(** P < 0.01, *** P < 0.001,  NS not significant P > 0.05), the
correlation coefficient (r),  and the number of samples  (n).

All years
1968-1969
1973-1974
TP
39 ± 3
48 ± 7
34 ± 4
Chi
25 + 3
37 ± 3
17 ± 4
b
0.98 ± 0.3
1.09 ± 0.6
-0.04 ± 0.7
P 7
E ^
53***
62**
NS
r
0.74
0.79
0.04
n
30
12
18
                                    106

-------
              _3
up to 120 mg m   indicates that P    is independent of population
                                 H13.X
densities in Lake Minnetonka.  The mean value  (± 95% confidence limits)
of P    is significantly  (P < 0.05) higher at  18-25° C (54 ± 5
    max    _i    _i                                     _i    _i
mg C mg Chi   day  ) than at 6-16° C (31 ± 7 mg C mg Chi   day  ).
These rates of carbon assimilation per unit chlorophyll at saturating
light were computed from rates of oxygen evolution with a photosynthetic
quotient of 1.2.  The corresponding rates of oxygen evolution were
173 ± 16 mg mg Chi"1 day'1 at 18-25° C and 99  ± 22 mg mg Chi'1 day"1
at 6-16° C.  Volumetric photosynthetic rates at saturating light also
depend upon concentrations of total phosphorus, but only during sum-
                                                     14
mer when population densities depend upon phosphorus.
                                                                    Q
If equation (6) is substituted in equation (1), then it can be shown
that
and that
                    7T    = TT/TT    = 	1	                    (8)
                     rel      max   1 + [E /(e c)]
                                          w   c
where TT    = ln(I /I ,) P   /e  is the maximum daily integral photo-
       max       o  z'   max  c                    J     °
synthetic rate attained by populations dense enough to attenuate all
photosynthetically active radiation.    Equation  (7) is an equation
for a rectangular hyperbola, indicating that integral photosynthetic
rates approach an upper assymptote (ir   ) as population densities
increase.  If daily average In (I /I  ,) is 2.7,   if P    is
               11           o  z      «       _.. max
54 mg C mg Chi   day  , and if e  is 0.02 m . mg Chl~ , then v
            _2    -I            c                           v max
is 7.3 g C m   day   at 20° C in Lower Lake Minnetonka.
The relative integral photosynthetic rate (ir  ..) is a dimensionless
parameter that ranges from 0 to 1, depending upon the proportion of
PhAR attenuated by phytoplankton.  Phytoplankton attenuate 50% of
the light and IT    = 0.5 at the chlorophyll concentration c' = ew/ec>
which is 41 mg m~  in the Lower Lake and 76 mg m   in Halsted Bay.
Population densities in Halsted Bay must be almost twice as great as in
the Lower Lake in order to attain IT    =0.5 because e  is higher in
                                   1TG-L                «
Halsted Bay.
                                   107

-------
Daily integral photosynthetic rates have been computed from changes
of oxygen concentrations (PQ = 1.2) in transparent and opaque bottles
filled with lake water and incubated at depth intervals for six hours,
beginning at noon.  The mean (± 95% confidence limits) daily integral
photosynthetic rate measured monthly (22 April - 7 October) during
                                                              _2
1969 at three localities in the Lower Lake was 2.2±0.4gCm   day
                                     14
(computed from Table 4 in Megard 1972  ), and the mean concentration
                              _o
of chlorophyll was 22 ± 5 mg m   (Table 4), corresponding to ir  -
                                                         -3   r
= 0.35.  The mean concentration  decreased to 14 ± 4 mg m   during
the comparable interval of 1973, and IT    therefore decreased to 0.2o.
However, the decrease of mean concentrations of chlorophyll during summer
(10 July - 10 September) indicate that the mean integral photosynthetic
rate decreased from 0.48 IT    (1968-1969) to 0.29 ir    (1973-1974),
                         ^max  -                   max
or from 3.4 to 2.1 g C m   day
The dominant phytoplankton of the Lower Lake during 1969 were Stephanodiscus,
Cyclotella, and Cryptophyta during April, May, and June.   A diverse
assemblage of Cyanophyta including Aphanizomenon, Anabaena, Oscillatoria,
Lyngbya, and Microcystis was dominant during summer and early autumn,
                                       14
when population densities were highest.    In contrast the dominant
phytoplankton in this basin during 1937 were Melosira, Fragilaria, and
    V   13
Lyngbya.
                           PHOSPHORUS BUDGET
The phosphorus budget for the Lower Lake is amenable to analysis, but
phosphorus enters most other basins from many diffuse sources which
are difficult to measure.  Exchanges between the Lower Lake and other
large basins may be neglected because the exchanges of water between
large basins are small and because concentrations of phosphorus in the
Lower Lake are similar to the concentrations in adjacent large basins.
The estimated annual influx of total phosphorus to the Lower Lake be-
tween 1 June, 1969, and 31 May, 1970, was 12.9 t (= 12.9 x 103 kg),
of which 69% came from sewage effluents (Table 6).   The annual loading
was therefore 0.5 g m~2 yr"1 (12.9 x 106 g * 26.2 x 106 m2).  The annual
loss of water and therefore of phosphorus through the outlet (0.01 t)
                                   108

-------
         Table 6.   PHOSPHORUS INFLUX TO LOWER LAKE MINNETONKA,
                     1 JUNE, 1969 - 31 MAY, 19703
Source
Sewage effluents
Tributary streams
Overland runoff
Q
Rainfall on lake
Septic tank drainage
Total
Quantity
tonnes
8.9
0.4
2.0
0.4
1.2
12.9
%
69
3
16
3
9
100
       Compiled by Harza Engineering Co.
       Estimated as 130 pounds/square mile from rural uplands and
              •
       510 pounds/square mile from urban land
                                                          T
       Concentrations in rainfall estimated to be 20 mg m
was negligible.  The quantity of total phosphorus in the Lower
Lake fluctuated between 7.6 and 19.3 t, and the mean was 13.4 t
(Fig. 7).  Virtually all the phosphorus that entered must have been
deposited in the sediments if the lake was in a steady state.  The
influx from sewage effluents and septic tanks was stopped during the
winter of 1971-1972, decreasing the annual influx 78%, to 2.8 t yr"
(0.1 g m~2 yr'1).
The response to the decreased influx was computed with the following
equation for phosphorus in a perfectly-mixed basin (A. G. Fredrickson
pers. comm., Vollenweider 1968  ):
                        V dC = i - (Q C + SAC)                       (9)
                          dT
where V = volume of basin
      C = concentration of total phosphorus
      1 = annual influx from all sources
     QQ = annual loss of water through outlet
                                  109

-------
                      I I  I I I I I I  I I I I I  I I I   till II I I I
                      JMMJ  SNlJM   jj M  M J SNJJ MMJ  SNj

                     1     1969       1970  '     1972          1973




 Figure 7.  Quantities and concentrations  of total phosphorus in Lower


 Lake Minnetonka before and after diversion of sewage effluents.  Dashed


 line indicates the change computed with equation 11.
      A = surface area of basin


      S = net sinking velocity of phosphorus lost to sediments.



If I = i/V and (Q  + SA)/V = I/8 , where  6  is a residence time
                 o              p         p

for phosphorus, then,



                          dC/dt  =  I  - (I/6 )  C,
                                                                    (10)
and the solution for the initial conditions C = C  and t = t  is
                                                 o          o



                  Ct= I6p + (Co~ iep} exp -
                                                                     (ID
If the average concentration during 1969-1970 (62 mg m  ) is assumed


to be a steady state concentration, then the residence time of phosphorus


may be computed from equation (10) where dC/dt = 0:
                               e  = c/i.
                                p

                           —3   —1
The influx  (I) was 60 mg m   yr  , hence
                                               1.1 yr.  If

                                                 -3   -1,
      (12)




remains
constant at the decreased rate of influx (13 mg m   yr  ), then the


concentration at the new steady state is given by equation (11) at

t = °°;



                             - I 6p = 14 mg nT3.


                                    no
                                                                    (13)

-------
 Concentrations this  low do not occur in x^ices  of  the  region, which
 suggests  that  the residence time of phosphorus is more than 1.1 yr.
 A more conservative  estimate may be obtained by assuming  that  the
 residence time is 2  yr, which corresponds  to a steady state concentra-
                -3                  -3
 tion of 26 mg  m   where I = 13 mg m  .
 The time  (t_  ,.)  required to achieve 50% of the new steady state if
 6  = 2 yr may  be computed by rearranging equation (11):
                   exp -  (t   /e ) = C  - 18 /C  - 16                (14)
                           0.5  p     t     P  o     p
                                    = 0.5
                               fc0.5  * 1'5 yr-

Total quantities and mean concentrations of total  phosphorus in the
Lower Lake before and after the influx decreased are shown in Fig.  7.
                                                       -3
The average annual concentration decreased from 62 mg m   1969 to
       -3
47 mg m   in 1973, which is 42% of the decrease required to attain
the projected steady state concentration.  The  new steady state will
be attained approximately seven years after the rate of influx de-
creased.
                               DISCUSSION
 Lakes  are  difficult  to  classify  on  the  scale  from  oligotrophic  to
 eutrophic  because  the criteria for  classification  are  ambiguous and
 subjective.  As  an alternative,  we  have suggested  classifying lakes
                                                     Q
 according  to relative integral photosynthetic rates.   The  relative
 integral photosynthetic rate  depends upon how PhAR is  partitioned be-
 tween  the  phytoplankton and their  environment , ranging from 0  (all
 PhAR attenuated  by water)  to  1 (all PhAR attenuated by phytoplankton) .
 It  is  an objective basis for  comparison, depending upon  (1) concentrations
 of  chlorophyll a.,  (2) the  coefficient for attenuation  of PhAR by a
 unit of chlorophyll  concentration  (e ) ,  and  (3)  the coefficient for
 attentuation of  PhAR by water and substances  other than phytoplankton
 in  the water  (e  )  (equation 8) .
               w
 It  is  difficult  to evaluate e and  e ,  but they  appear in equation  (8)
 as  a ratio, which  equals the  ratio  k     /k,       where k
 and  k    .   are  coefficients  for  the  attenuation of  the most-penetrating
     c mm               -Q   - g
 spectral  region of PhAR.   '      The  total  attenuation coefficient  for
                                   111

-------
 the  most-penetrating wavelength,  k .   = k   .   + k      c, is easy
                                   mm    w nun    c mm
 to measure with a  photometer equipped with suitable filters, and k
 and
                                                                   w min
     _ m1n   -.be estimated from the intercept  (k    .  )  and  the  slope
     L- ui-Lu                                       w min             c
^kr mir.) of  the equation for the linear regression of  k  .  on  concentra-
                     11  1?  1Q                        min
tions of chlorophyll.   '   ' ^^
Relative integral photosynthetic rates at maximum population densities
of phytoplankton in four Minnesota lakes (Lower Lake Minnetonka,
Halsted Bay, Shagawa Lake, and Budd Lake)  are   compared with those
in three British lakes  (Windermere, Esthwaite Water, and Loch  Leven)
and two African lakes  (Victoria and George) in Table 7.  Most  observers
would probably consider Windermere (IT    = 0.32) and Victoria  (TT
=  0.38)  as  oligotrophic  or mesotrophic  and the others  (IT  .,  = 0.56-0.88)
                                                         rel
           Table 7.  RELATIVE INTEGRAL PHOTOSYNTHETIC RATES

                                         _o
Computed for maximum concentrations (mg m  ) of chlorophyll a_  (c)
The concentration c' = e /e  is the concentration of chlorophyll
                        w  c
at which phytoplankton attenuate 50% of PhAR.
Lake
Windermere, England
Victoria, Africa
Shagawa, Minnesota
Lower Lake Minnetonka
1968
1969
1973
1974
Halsted Bay (1974)
Budd, Minnesota
Loch Leven, Scotland
Esthwaite, England
George, Uganda
c
7
5
108

56
43
39
30
89
170
250
170
1100
c'
15
8
83

41



62
60
78
50
159
TT .
rel
0.32
0.38
0.56

0.58
0.51
0.49
0.43
0.59
0.74
0.76
0.78
0.88
reference
11
20
8





8
8
19
18
12
                                   112

-------
as eutrophic or polytrophic.  The differences between these lakes
depend primarily upon differences of maximum concentrations of
                       —3                           —1
chlorophyll (8-160 -mg m  ) and of e  (< 0.16 - 2.5 m  ); e  varies
                                   w                  2   c   -1
only from 0.01 to 0.025 and it is usually about 0.02 m  mg Chi  .
Therefore variations of e  are responsible for most of the variation
                         w
of c1 = e /e , the concentration of chlorophyll at which phytoplankton
attenuate 50% of PhAR.
The relative integral photosynthetic rate at maximum population densities
is misleading however, because the average relative rate for the
lakes in temperate continental lakes is lower than the average for
lakes in other climates, where there are relatively small seasonal
variations of population densities.  Thus, although the maximum relative
rate in Lower Lake Minnetonka was 0.58 in 1968, the average during the
open-water season was 0.35 in 1969 and 0.26 in 1973, less than the
maxima for Windermere and Lake Victoria.  Computations of mean
relative integral photosynthetic rates would therefore be required
for comprehensive comparisons; the only data required for such compari-
sons are periodic measurements of chlorophyll concentrations and of
subsurface light.
                                SUMMARY

Maximum population densities of phytoplankton in Lower Lake Minnetonka
were three or four times greater in 1968 and 1969 than in 1937.
The linear regression of concentrations of chlorophyll 
-------
                                                                  _3
The annual mean concentration of phosphorus decreased from 62 mg m
                  _3
in 1969 to 47 mg m   in 1973, which is almost 50% of the decrease
required to attain the new steady state concentration predicted with
a balance equation for phosphorus in a perfectly-mixed basin.  Virtually
all the phosphorus lost from the lake since the influx decreased has
been deposited in the lake sediments, because the quantity lost through
the outflowing stream is very small.
The trophic state before and after the influx of phosphorus decreased
is described objectively by changes in the relative integral photosynthetic
rate, which indicates the fraction   of photosynthetically active radiation
attenuated by phytoplankton populations on a scale from 0 to 1.  The
relative integral photosynthetic rate is the integral photosynthetic
rate relative to the rate attained by a population dense enough to
attenuate all subsurface light.  The maximal relative integral photo-
synthetic rates, attained by the densest populations in Lower Lake
Minnetonka, were 0.58 in 1968 and 0.43 in 1974,  The latter is somewhat
higher than the maxima at highest population densities in Windermere,
England,  (0.38) and Lake Victoria, Africa (0.32).  The mean relative
integral photosynthetic rate during the ice-free season decreased
26% from 0.35 in 1969 to 0.26 in 1973, as mean concentrations of
                                      —3               —3'
chlorophyll decreased from 22 ± 5 mg m   to 14 ± 4 mg m
                                   114

-------
                               REFERENCES


 1.  Report on bacteriological and chemical sampling of Lake Minnetonka,
     1966-1967.  Schoell and Madson, Inc., Engineers and Surveyors.
     Hopkins, Minn.  1967.  52 p.

 2.  Overall plan for water management, Minnehaha Creek Watershed
     District.  E. A. Hickok Associates, Consulting Hydrologists,
     Wayzata, Minn.  1969.  79 p.

 3.  A program for preserving the quality of Lake Minnetonka.  Harza
     Engineering Co.  State of Minnesota Pollution Control Agency.
     Minneapolis, Minn.  1971.

 4.  Zumberge, J. H.  The lakes of Minnesota, their origin and classifica-
     tion.  Minn. Geol. Surv. Bull. 35.  1952.  99 p.

 5.  Wright, H. E. and R. V. Ruhe.  Glaciation of Minnesota and Iowa.
     In:  H. E. Wright and D. G.  Frey (ed.).  Princeton Univ. Press.
     1965.  p. 29-41.

 6.  Waddington, J. C. B.  A stratigraphic record of pollen influx to
     a lake in the Big Woods of Minnesota.  Geol. Soc.  Amer. Spec. Paper
     123:263-281.  1969.

 7.  Florin, M. and H. E. Wright, Jr.  Diatom evidence for the persistence
     of stagnant glacial ice in Minnesota.  Geol. Soc.  Amer. Bull.
     80:695-704.  1969.

 8.  Megard, R. 0., P. D. Smith,  A. S.  Knoll,  and W. S. Combs, Jr.
     Attenuation of light and photosynthetic rates of phytoplankton.
     Submitted for publication to Limnol.  Oceanogr.  1975.

 9.  Tailing, J. F.  Photosynthetic characteristics of some freshwater
     plankton diatoms in relation to underwater radiation.  New Phytol.
     56:29-50.  1957.

10.  Vollenweider, R. A.   Models for calculating integral photosynthesis
     and some implications regarding structural properties of the community
     metabolism of aquatic systems.  In:  Prediction and measurement
     of photosynthetic productivity.   Proc. IBP/PP Tech. Meeting, Trebon,
     Czechoslovakia.  Wageningen.  Centre Agr. Publ. Doc. 1970.
     p. 455-472.

11.  Tailing, J. F.  Self-shading effects in natural populations of a
     planktonic diatom.  Wett. Leben. 12:235-242.  1960.

                                    115

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12.  Ganf, G. G.  Incident solar irradlance and underwater light penetra-
     tion as factors controlling the chlorophyll a^ content of a shallow
     equatorial lake (Lake George, Uganda).  J. Ecol.  62:593-629.  1974.

13.  Wood, E.  An ecological study of Lower Lake Minnetonka.  M. S.
     Thesis.  Univ. Minn.  Minneapolis.   1938.  39 p.

14.  Megard, R. 0.   Phytoplankton, photosynthesis, and phosphorus in
     Lake Minnetonka,  Minnesota.   Limnol. Oceanogr. 17:68-87.  1972.

15.  Bannister, T.  T.   Production equations in terms of chlorophyll
     concentration, quantum yield, and upper limit to production.
     Limnol. Oceanogr. 19:1-12.  1974.

16.  Vollenweider,  R,  A.   Calculation models of photosynthesis-depth
     curves and some implications regarding day rate estimates in
     primary production measurements.  Mem. 1st. Ital. Idrobiol. 18(Suppl.)
     425-257.  1965.
                           it
17.  Vollenweider,  R.  A.   Moglichkeiten und Grenzen elementarer Modelle
     der Stoffbilang von Seen.  Arch. Hydrobiol. 66:1-36.  1968.

18.  Tailing, J. F.  The underwater light climate as a controlling
     factor in the production ecology of freshwater phytoplankton.
     Mitt. Internat. Verein. Limnol. 19:214-243.  1971.

19.  Bindloss, M.  Primary productivity of phytoplankton in Loch Leven,
     Kinross.  Proc. Roy. Soc. Edinburgh (B) 10:157-181.  1974.

20.  Tailing, J. F.  The photosynthetic activity of phytoplankton in
     East African Lakes.   Int. Rev. ges. Hydrobiol. 50:1-32.  1965.

21.  Bright, R. C.   Surface water chemistry of some Minnesota lakes,
     with some preliminary notes on diatoms.  Univ. Minn. Limnol.
     Res. Center Interim Report No. 3.  59 p.  1968.
                                    116

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                  REPORT ON THE MINNEAPOLIS  CITY LAKES


                              Joseph  Shapiro
                       Limnological  Research Center
                         University  of  Minnesota
                          Minneapolis,  Minnesota


                              I.  INTRODUCTION

     A.   Past History

     The five lakes discussed in this report make up the so-called
Minneapolis Chain of Lakes.  They are all within the Minneapolis city
limits (see Figure 1).  Four of them, from north to south, Brownie,
Cedar, Isles, and Calhoun, are connected by  channels made between 1910
and the early 1920's, but Lake Harriet, the  southernmost, is isolated.
Lake of the Isles was dredged extensively about 1920.  The four upper
lakes have had chronic low water problems for several decades because of
their connection with the groundwater table, the level of which has not
been high enough to sustain them.  In order  to resolve this low water
problem, storm drainage from the surrounding city was directed into the
lakes beginning in 1912 and continuing to the present.  In addition,
groundwater used by nearby companies for cooling purposes has been added
to the four upper lakes.  In recent dry years, water from the Mississippi
River and city drinking water has been pumped in. As a consequence,
particularly of the storm drain inputs, the  lakes have become increasingly
eutrophic in recent years.
                                   117

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©Birch Pond
  Broirnie  Lode      \Loriag Pond
     Cedar Lake
            Lake of  the Isles
                            /Diamond Lake
                          w
              \jSrass Lake           *>
                  Fig.  1.  Location map of study area.
                                      118

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       Transparencies in Minneapolis Lakes  in  1927  and 1971,  m


             Lake             July  29,  1927 July-August,  1971
Brownie
Cedar
Isles
Calhoun
Harriet
4.1
3
2.6
3.4
4.1
1.9
1.2
.5
1.7
3
     II.  Geography

          A.  Latitude and Longitude -  45°N  93°W

          B.  Altitude

              The surface of the upper  lakes  is at  an  altitude  of

     260 m above mean sea level.  Lake  Harriet's  surface  is  at  an

     altitude of 258 m.


          C.  Catchment Area


                   Lake               Are a,  ha  (inc. lake)

                   Brownie               47
                   Cedar                 163
                   Isles                 285
                   Calhoun               761
                   Harriet               480


          D.  Climatic data

              Mean monthly air  temperatures  (°F)  are approximately

     as follows:


         JFMAMJJASOND

High     22     25    35    55    65     75     84     82     70     58     43   27

Low       4     7    20    36    45     58     64     62     52     43     25   14


                                    119

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The lakes begin to freeze over in November and breakup generally
occurs in mid-April.  Ice thickness may reach 75 cm.  Snow may
be present from October to May but the peak snowfall is from
November to March.  Total snowfall may reach 150 cm.  Approximate
average monthly precipitation as follows (in cm) :

  JFMAMJJASOND
 2.0  2.0  3.6  6.1  8.4  10.7 8.6  8.6  7.6  4.6  3.6  2.3

Summer winds average 190° (SSE)  with a mean velocity from April
to October of 14.6 kph.   Evaporation exceeds precipitation by
12.7 cm annually and by 17.8 cm between April and October.
Total evaporation averages about 99 cm per year.

     E.  Geology
         All of the lakes are ice block lakes formed about
11,000 years ago.  They are embedded in sand and gravel with
some clay.  The bottom sediments are typical deep-water sediments
of productive lakes, total thickness unknown.  Sfediments in Lake
of the Isles are only about .5 m deep and are underlaid by
undecomposed plant remains as this lake was essentially a swamp
until its dredging in the 1920s.  Land erosion in the catchment
area is probably negligible as the whole area is urban and has
long been settled.  Pollen analysis of the deep waters of Lake
Calhoun and Harriet shows a sedimentation rate of about 3 mm
per year.
     F.  Vegetation
         Virtually all of the area not covered by impervious
                               120

-------
surfaces such as houses, roads, walks, and alleys is planted


in lawn grasses.  A large number of trees, especially elms and


oaks, is present in the catchment area.



     G.  Population

                                                  2
         Population density is high—about 1550/km .



     H.  Land use


         Excluding water areas, 83% of the area surrounding


the lakes is urban, and includes residential use, commercial


and service use, institutional use, and transportation.  The


remaining 17% is open land, and includes parks, a golf course,


a cemetery, islands in Lake of the Isles, and grassy areas


immediately surrounding the lakes.



     I.  Water use


         The lakes are used primarily for fishing, swimming,


sailing, and canoeing.  No water is taken for  drinking purposes



     J.  Sewage and effluent discharge


         No sanitary sewage or industrial effluents reach the


lakes.
III.  Morphometric and hydrologic characteristics
      A., B., C., D., and E.  See Table below.
                                                Est. % area
                                 121
Epilimnion
Lake
Brownie
Cedar
Isles
Calhoun
Harriet
Area
(ha)
7.3
69
42
170
143
Max. depth
(m)
15
15
11
27
26
Mean depth
(m)
6.8
6.1
2.7
10.6
8.8
Volume
10 V3
0.5
4.22
1.12
18.0
12.5
less than
3 m deep
15
80
5
15
thickness ,
July - Aug
3
4
4
6
6


-------
         F.  Duration of stratification
             The lakes are stratified for approximately six months

    from late April to late October.


         G.  Sediments

             The sediments are highly organic.  Lake Calhoun has

    2000 micrograms P/gram dry weight in the surface sediments and

    800 micrograms P/gram dry weight below 10 cm.  Lake Harriet has

    3000 micrograms P/gram dry weight at the surface, falling to

    800 at 25 cm/ then rising again to high and variable concentra-

    tions of between 2000 and 6000 grams P/gram dry weight.


         H.  Variation of precipitation

             See IID above.
         I.  Inflow and outflow of water
Lake

Brownie
Cedar
Isles
Calhoun
Harriet
Total inflow 103m3
       252
      1281
      1812
      5012
      5157
% lost to groundwater

         79
         61
         82
         75
         81
% lost to evaporation

         21
         39
         18
         25
         19
         There are no functional surface outlets.  The percentage

    of groundwater loss was determined by resolving the hydrologic

    budget, i.e. by accounting for all inputs and outputs except

    groundwater.  Because the upper lakes are connected, this

    procedure may not be entirely correct.  If, for example, Lake

    of the Isles has a completely impervious basin, its excess water

    will run to Lake Calhoun which would then have a higher loss to

    groundwater than was calculated.  This would not change the water

                                   122

-------
residence time for Isles but Lake Calhoun would appear to have

a longer residence time than it really has.

     J.  Currents
         No currents are known.


     K.  Water retention time

         With the possible error noted in I above, retention

times are as follows:

                                   Water retention
            Lake                    times (yrs)

            Brownie                    1.98   (probably less for the
                                              mixolimnion because of
                                              meromixis)
            Cedar                      3.30
            Isles                       .62
            Calhoun                    3.59
            Harriet                    2.43


IV.  Limnological characterization

     A.  Physical

         1.  Temperature

             All of the lakes fetratify thermally.  Surface

temperatures range up to 26°C in summer but typically are

20-22°C.  Bottom temperatures are 5-7°C except in Brownie Lake

which is meromictic from road salt.  Its bottom temperatures

are higher than those at 6-8 m which are at 4°C.  The mixolimnion

extends down to 4 m in Brownie Lake.

         2.  Conductivity

                              1974 range in surface specific
  Lake                         conductance (micromhos/cm).

  Brownie                                  400-475
  Cedar                                    400
  Isles                                    380-470
  Calhoun                                  400-500
  Harriet                                  360-425
                                123

-------
         3.  Light

             No light measurements were made other than

Secchi disk transparencies.


         4.  Color

             The lakes have no apparent color.

         5.  Solar radiation

             No measurements were made.


     B.  Chemical

         1.  pjl

            Epilimnetic pH values are high throughout the
growing season.
            Lake
            Brownie
            Cedar
            Isles
            Calhoun
            Harriet
1971-72 pH maximum in
   surface waters	

        8.91
        9.30
        9.49
        9.10
        8.81
         2.  Dissolved oxygen

             All of the lakes have anoxic hypolimnia from  late

May until  turnover in October-November.  Anoxia in Isles begins

somewhat earlier.  Brownie Lake has an anoxic hypolimnion  year

round because of its meromixis.

         3.  Phosphorus

             a.  Orthophosphorus-P

             Calhoun, Harriet, and Cedar surface waters contain

5 ppb or less PO.-P during the summer.  Isles and Brownie  surface-

waters contain 10 ppb or less during the summer.  Bottom water

concentrations are as follows:
                                 124

-------
                   Lake
                        PO .-P, miprograms/I
                   Brownie
                   Cedar
                   Isles
                   Calhoun
                   Harriet
                            >1600
                               738
                               601
                               379
                               255
                 b.   Total P
    Lake           Surface range, ppb P

    Brownie               30-40
    Cedar                 30-40
    Isles                 70-100
    Calhoun               40-50
    Harriet               40
                                  Mean concentration
                                      whole lake
                                          55
                                         110
                                         106
                                          62
             4 .  Nitrogen

                 No total nitrogen figures are available.  Surface

    NO,-N is less than 5 ppb in the summer.  Surface NH^-N is less

    than 50 ppb in the summer.
             5.   Alkalinity

              Lake

              Brownie
              Cedar
              Isles
              Calhoun
              Harriet
                            surface ranges
                           1971-1972 meg/1

                             2.47-2.72
                             1.41-2.18
                             1.36-2.62
                             1.59-2.27
                             1.84-2.47
             6.   Major ions
Lake
Brownie
Cedar
Isles
Calhoun
Harriet
Na
3.11
1.
1.
1.
38
64
64
1.21
K

.06
.08
.09
.10
.10
                             Surface values 11/16/71
Ca

1.
1.
1,
1.
99
63
63
55
Mg
1
1
1
1
,04
,03
,01
 22
              1.63
         1.02
.28
.42
.33
.31
.21
Cl

3.64
1.61
1.91
1.93
1.54
HC03

2.65
2.26
2.31
2.36
2.41
                                    125

-------
Total iron concentrations in all the lakes averaged about 20 ppb.
         7.  Trace metals

             No determinations were made.

     C.  Biological characteristics

         1.  Phy top 1 ankton

             a.  chlorophyll a
Lake

Brownie
Cedar
Isles
Calhoun
Harriet
1971 surface values ppb

       4.3-24
       2.4-27
       15-72
       3.4-37
       1.2-27
mean surface concentration
	July-August 1971	

           5.6
          20
          53
           6.0
           3.5
             b.  Primary production

                 No measurements.

             c.  Algal assays

                 No algal assays as such.  Determinations of

alkaline phosphatase activity show low values until late July

and high values through September.

             d.  Identification and count
                 The five dominant algae in 1971-72 are listed
be low
           Lake

           Brownie
           Cedar
                 Algae

                 Fragilaria crotonensis
                 Mougeotia sp.
                 Asterionella formosa
                 Cryptomonad sp. 3
                 Oocystis spp.

                 Scourfeldia cordiformis
                 Anabaena planctonica
                 Cryptomonad sp. 3
                 Oscillatoria agardhii
                 Aphanizomenon elenkinii

                  126

-------
              Lake               Algae

              Isles              Scourfeldia cordiformis
                                 Aphanizomenon flos-aquae
                                 Anabaenopsis raciborskii
                                 Oscillatoria agardhii
                                 Asterionella formosa

              Calhoun            Aphanizomenon flos-aquae
                                 Anabaena planctonica
                                 Stephanodiscus niagarae
                                 Stephanodiscus-Cyclotella spp,
                                 Cryptomonad sp. 3

              Harriet            Aphanizomenon flos-aquae
                                 Ceratium hirundinella
                                 Oocystis spp.
                                 Cryptomonad sp. 3
                                 Stephanodiscus niagarae


                              Volume % of blue-greens during
     Lake                     	July and August 1971	

     Brownie                               /. 5
     Cedar                                  99
     Isles                                  99
     Calhoun                                95
     Harriet                                78
            2 .   Zo op lank ton

                a.  Identification and count

                         Numbers of species in each lake
Lake         Cyclops     Piaptomus     Daphnia     Chydorus sphaericus

Cedar           111             present
Isles           1           .1            4             present
Calhoun         325             present
Harriet         113             present


   The numbers  are very variable.


            3.   Bottom fauna

                Bottom fauna was very sparse in all the lakes.

            4.   Fish

                Fish in the lakes are mostly yellow perch, blue-gill

   sunfish, and black crappies.  Some northern pike are present and

                                   127

-------
    bass  are abundant in Cedar and Isles.   Isles has many carp.


             5.   Bacteria

                 Unknown.

             6.   Bottom flora

                 Unknown.

             7.   Macrophytes


    Brownie     A ring of Nuphar variegatum to a depth of 1.8 m.

    Cedar       Nuphar and Nymphaea with Potamogeton and Ceratophyllum

                in significant quantities.

    Isles       Ceratophyllum and Potamogeton in water of less than

                1. 8 m.

    Calhoun     Potamogeton and Ceratophyllum in less than 1.8 m.

    Harriet     Ceratophy1lum and Elodea in less than 2.5 m.



    Cedar Lake is the only lake in which the weeds are very abundant.



    V.  Nutrient budget summary

        A.  Phosphorus

                                   kg/year/lake in 1971
Sources            Brownie      Cedar     Isles     Calhoun     Harriet

Waste discharges
 (includes city
  water and air
  conditioning
  water)             24.6        0.2         0        13.3         0

Land runoff
 (via storm drain
  and direct)

Estimated
precipitation

Estimated ground-
water input


Total                85.9      241         851       1461         101
57.5
3.8
0
205
36
0
828
23
0
1357
91
0
890
72
54

-------
      B.  Nitrogen

          No data are available.

      C.  Other budgets

          None.
  VI.   Discussion

       A.  Limnological characteristics

       B.  Trophic state

           By most criteria all of these lakes would be classed

  as eutrophic.  Data from 1933 show considerably lower concen-

  trations of algae, lower pH, higher dissolved oxygen, and higher

  transparency.  There is no question that the addition of storm

  runoff has been responsible for the changes.


       C.  Trophic state vs. nutrient budgets
Lake

Brownie
Cedar
Isles
Calhoun
Harriet
grams P/itr/yr
     1.18
     0.35
     2.06
     0.88
     0.71
Mean depth/detention time

        3.43 (2.02 mixolimnion)
        1.85
        4.35
        2.95
        3.62
       Plotting the results from the above table would suggest

  that the lakes should form a series with Isles being most

  eutrophic and Cedar least so.  While some indicators of trophic

  state would corroborate this, e.g. total P, others, such as

  chlorophyll, epilimnetic pH, and transparency would not, i.e.

  Isles is most eutrophic on any basis but Cedar is least so with

  some, and not least eutrophic with others.  Furthermore, the

  situation changes from year to year.  Thus, if summer chlorophyll
                               129

-------
concentrations are used as the index, Lake of the Isles appears
to be becoming less eutrophic in recent years while Calhoun and
Harriet, after several years of lessened eutrophy, appear to be
becoming more eutrophic (Figure 2),   These chlorophyll data are
substantiated by transparency measurements and measurements of
algal abundance as shown in the table.  So far as is known, the
nutrient budgets of the lakes have not changed in recent years.
Therefore, the question arises, why have the lakes undergone
these changes?  A variety of hypotheses have been tested and
discarded.  For example, neither Lake Harriet nor Lake Calhoun
appear to have more nitrogen fixing algae in 1974 than in
1971-72, as judged by heterocyst frequencies.  Neither has
there been a related change in either total rainfall or the
seasonal pattern of rainfall that brings the nutrients into
the lake.  It appears rather that changes within the lakes
themselves are responsible for the changes in the manifestation
of eutrophy, i.e. changes have occurred despite the fact that
the total phosphorus has remained constant (see table for Lake
Harriet data) .
     One explanation that appears likely is that the algal
abundance is being affected by the grazing of zooplankton and
that the higher chlorophyll concentrations occur as a result
of less grazing.  Substantiation for this is shown in Figure 3
where the transparency in Lake Calhoun during 1973 appears to
correlate very well with the abundance of Daphnia.  If this is
a correct explanation then it implies that zooplankton grazing
pressure in the lakes has been changing.  This in turn could be
                                130

-------
    70
    60
rO
    50
               ISLES
 —J  40
  V
 X
 CL
 O
30
 O
    20
 O
        \
      \
                                            \
\
•CALHOUN
           V
                 \
     HARRIET
               \
                                              \
         \
     68
         69
        70      7\
              YEAR
              72
73
74
   Fig. 2.  Mean surface chlorophyll concentrations for the period July-September.
                          131

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            Lake  Harriet


Date
1968
1969
1971



1972




1973



1974





7/23
7/29
7/19
8/2
8/24
9/13
7/6
7/24
8/9
8/22
9/13
7/11
7/25
8/23
9/19
7/22
8/20
9/16
Secchi
Disk
(feet)
-
5.0
11.3
5.2
5.6
5.9
14.0
11.0
9.3
8.4
10.0
10.0
7.0
9.0
8.8
5.5
3.5
6.6
                 Surface
                 Chlorophyll
                   (ppb)

                   16.0

                   10.0

                    1.7
                    4.5
                    2.8
                    3.2

                    2.4
                    2.8
                    4.2
                    3.4
                    4.0

                   (3.9)
                    3.9
                   24.0
                   47.4
                   14.8
Surface
Algae
(mg/1)
Surface
Total P
 (ppb)
  4.4

  1.1
  0.61

  0.61
  0.33
  1.1
  1.5
  0.70
 10.2
 12.0
 10.2
 41
 43
 41
 42

 37
 37
 39
 38
 38

 35
 40
 35
 22

 64
 45
 42
(   )  = values  from 2.5 m,  not used in average.
                   132

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   0


   2



 -' 4


   6



   8

LJ



°-12


< 14

o:

   16


   18


   20
                   TRANSPARENCY
                      DAPHNIA

                                            2000
                                                 O
                                                 >
                                                 T)
                                            JOOO J"
                                                 o
                                                  OJ
      MAY   JUNE  JULY   AUG.  SEPT.
                                             0
Fig. 3.  Relationship between Secchi Disk Transparency and Daphnia abundance

      in Lake Calhoun during 1973.


                        133

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a result of changes in the populations of such fish as yellow



perch which are zooplanktivorous.   In fact, we have recently



begun a program to test the possibility of using carnivorous



fish to control zooplanktivorous fish, so that zooplankton



grazing could increase and so help control algae.



     Because of such biological effects as suggested above on



the manifestations of eutrophication, it appears extremely



unlikely that the loading concept will ever be linked in a



precise fashion with trophic state.
                               134

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                           SECTION  III - NEW YORK


                   A DESCRIPTION OF THE TROPHIC STATUS AND

                 NUTRIENT LOADING FOR LAKE GEORGE, NEW YORK
                                      «•


                   James J. Ferris and Nicholas L. Clesceri
               Rensselaer Fresh Water Institute at Lake George
                       Rensselaer Polytechnic Institute
                                Troy, New York
                               I. INTRODUCTION


     Lake George is located in the eastern Adirondack Mountains of New York
State (Fig.  1), and has been under investigation by scientists and engineers
of the Rensselaer Fresh Water Institute as well as by other educational and
governmental bodies within the region.   The lake has served as an aquatic site
for the Eastern Deciduous Forest Biome  of the International Biological Program.
Much of the data presented was collected as part of that multidisciplinary,
ecosystem-wide study.

     Lake George lies  in a glacial-scoured basin of Precambrian metamorphic,
plutonic and igneous rock, with small patches of Cambrian deposits mainly at
the southern end of the basin.  Most of the drainage basin is covered with
shallow soil from glacial debris with numerous outcroppings present.

     Prior to the colonization of the New World, Lake George was part of a
natural trail, and the site of numerous Indian conflicts.  Its strategic
location between the Hudson River and Lake Champlain made it an area of battle
in both the French and Indian Wars and  the Revolutionary War.

     During the latter part of the nineteenth century, mining operations in
the region produced a representative supply of the nation's high-grade graphite
as well as some iron ore.  An active logging industry was also present at this
time which supported several mills in the Village of Ticonderoga, located on
the extreme north end of Lake George.  Virtually all this industry, however,
ceased within the first three decades of the twentieth century.

     It has been replaced by a flourishing tourist trade, drawn by the beauty
of the lake and its scenery.  The resort aspects of the area were enhanced
by the construction of the Adirondack Northway in 1967, which made the lake
far more accessible to the large urban areas to the south and north.
                                     135

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                                               a

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136

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                                              TICONDEROGA  B MILL
         LAKE  GEORGE
                         HAGUE  BROOK  BASIN
          NORTHWEST  BAY BROOK  BASIN
                                        RENSSELAER
                                        FRESH  WATER
                                        INSTITUTE
                                        AT  LAKE
                                        GEORGE
            INDIAN  BROOK  BASIN
          ENGLISH BROOK
             BASIN
          WEST  BROOK
             BASIN
                                                 SHELVING  ROCK
                                                 BROOK  BASIN
                                                        0  12345

                                                        SCALE   IN MILES
             Figure  2.
   QLAKE SAMPLING  STATIONS

Location of Lake  George Sampling Stations.
Not located on  the map  are the following stations:

1. Smith Bay and Burnt  Point are located immediately  east of Station 6.
2. Lake George  Village  is located in the extreme  southwestern corner of Lake
   George  (in the West  Brook drainage basin).
3. Tea Island is located immediately to the west  of Station 1.
4. Diamond Island is  located immediately to  the south of Station 2.
                                       137

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II.   BRIEF GEOGRAPHIC DESCRIPTION OF WATER BODY

         Lake George  is  a  relatively large  lake located  in the south-
eastern Adirondack  Mountain region of New York  State.   It lies within
the basin boundaries of latitude 43°22' and 43°51' North and longitudes
73°24' and 73°47' West.   The  lake  surface  stands at 97 meters above
                                    o
sea level,  and encompasses  114  km .   The drainage basin  surface
area is 492 km^, giving a total  catchment  area of 606 km^.  Thus,
the tributary watershed to  lake surface  ratio is only 4.  3.

         In general,  the  climatology of Lake  George is  typical for the
humid continental climatic  region of the  Northeastern  United States
(Stewart,  1971,  1972).   1970-71  monthly air  temperatures are presented
in Table  1 for the Lake  George  basin.   Long term  averages at Glens
Falls, located  approximately seven  miles south of Lake  George are
-7.2°C in January and 21°C in July.

         Wind pattern  analysis  by Stewart (1972)  shpw  that for  the
period of September 1971 through August 1972,  wind speed  averaged
5.65 jh 0.65  knots (based on monthly  averages).   Wind  direction is
from the  south  or southwest during the  warmer months, but shifts to
the north or northwest in November,  December,  February, March and
April.

         Lake evaporation and  evapotranspiration figures for the  Lake
George catchment area are presented in Table  2.   Evaporation  has
been  calculated using  the Penman Method and the evapotranspiration
from a water balance  of the active  soil  zone.
General Geologic  Characteristics

        Lake George occupies a graben in Precambrian bedrock.  This
bedrock consists  of plutonic,  metamorphic and igneous  rock,  for  example,
gneisses and  schists, syenite, granite and gabbro.  At  a few places
along the  shore of the southern Lake  George basin are  exposures of
Cambrian sandstones  (Potsdam  sandstone)  and  dolostones  (Little  Falls
dolomite).

        The linear straight shorelines and sheer  slopes are the combined
effect of erosion  following prominent  faults and a deepening of the fault-
controlled valleys  by  the  sweep of the Pleistocene glaciers  which deepened
the rock channels.  Prior to  glaciation,  two rivers drained the Lake
George  basin.   One  stream originated in  the narrow trench now occupied
by Northwest Bay  Brook and  flowed into the  southern Lake  George basin;
the second  river  flowed from the Narrows northward.   A preglacial
divide  existed where the Narrows are now located.   When the glaciers
plowed their way  through the  deep narrow Lake George Valley they
                                   138

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       Table 2.  EVAPORATION AND EVAPOTRANSPIRATION
          (1971  WATER YEAR) FOR  LAKE GEORGE,  N.Y.*
      Date
Lake  Evaporation
Evapotraq
Month
October
November
December
January
February
March
April
May
Inches/day^
0.06
0,04
0.03
0.02
0.03
0.05
0.07
0.11
Jnches/ month
1.91
1.18
0.80
0.67
0.81
1.42
2.19
3.51
Inches /day
0.06
0.04
0.03
0.02
0.03
0.04
0.06
0.10
Inches /month
1.74
1.11
0.78
0.63
0.74
1.26
1.91
3.06
spiration
 *(Colon, 1972)

deepened  the Narrows  by ice  erosion.   The waters  of  Lake George are
now  held  in place by Pleistocene glacial sediments  which block the river
outlets  at the north and  south end  of the lake.   At  the south end  of the
lake glacial sand  and  gravel deposits  rise  500  feet  above lake  level.
After the  retreat  of the  glaciers Lake  George  was a glacial lake  as
evidenced by the presence of  varved clay flooring the bottom of the lake
in the Narrows; this varved clay also  occurs above the present lake
level at elevations up to 750 to 800 feet.

        Surficial  sediments of the  Champlain basin  of  which Lake George
forms a part  have been  mapped.   Sand and gravel are abundant in the
delta and  ice-contact gravels  southwest of  Lake George Village (Schoettle
and  Friedman,  1971).
Vegetation

        Hemlock (72% of stands),  sugar maple  (69%),  white pine  (64%),
red maple and northern  oak  (57%)  are the  most frequently encountered
of 35 tree species occurring in 75 randomly selected stands  in the  Lake
George drainage basin.   Hemlock leads in density (32% stands),  white
pine (13%),  beech (12%), northern  red oak (9%),  and red/sugar maple
                                    140

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(8%).   Distribution patterns of hemlock and pine shows the former is
most  abundant in  sloping stands at the lowest elevation (100 m) and gener-
ally prevail on the east side of the basin,  while white pine is  best
represented in level  stands about  200 m,  but uncommon  on the east  side.
Forest composition of  our  random sample  for the drainage basin differs
slightly from  1970 estimates by Northeast  Forest Experiment  Station
in that pine-hemlock stands are more  common (42%-18%) and  elm-ash-
red maple and spruce-fir less common (3%-17%  and 0%-7%) (Nicholson
and Scott,  1972).
Population - See Tables  3  and 4.
Land Usage  - Data  are not available.
Use  of Water

        Primarily drinking,  aesthetics,  sport  (i. e. ,  boating,  fishing,
SCUBA  diving,  swimming,  etc. ),  and all other  recreational purposes.
Sewage and Effluent Discharges

         The types of wastewater discharges  in the Lake George drainage


           Table 3.   POPULATION DISTRIBUTION IN THE
                    LAKE  GEORGE,  N. Y.  BASIN*
                     South Lake Basin
North Lake Basin
Population
Type
Permanent,
Year -Round
Summer Camp
Resort Hotel
and Motel
Total Avg.
Summer
Number Total
Sev/ered Number
2,930
1,750

9,111
13,791
4,445
8,775

12, 558
25,778
Number Total
Sewered Number
0
0

0
0
1,130
3,205

47
4,382
  * Compiled from  1970 Census  data.
                                   141

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basin are:  1) secondary treated  (trickling filter plant) from the  Village
of Lake  George Sewage  Treatment Plant onto natural sand beds,  2)  pri-
mary treated (Imhoff tank) discharged onto  natural  sand beds from the
Town of Bolton facility,  3)  septic  tank-leach field effluent,  and 4) pit
privy discharge.   There is no industrial discharge.   Population data
relative  to this are  seen in  Table 4.
III.   MORPHOMETRIC  AND HYDROLOGIC  DESCRIPTION  OF  WATER
      BODY (at 97.25 m or 319  ft.  amsl)

Surface Area of Water  -  114 sq. km (44 sq. mi.)

         1.   Length  - 51  km (32 mi.)
         2.   Width - Maximum = 4.0 km (2.4 mi.)
                     Average  =  2.3 km (1.4 mi.)
         3.   Shoreline  Length  -  209.6 km (131  mi.)

Volume of Water -  2.1 km3  (0.5 mi.3)

Regulation - Lake George Water Levels (as described in Section 38 of
         the New York State Navigation Law)

        Any dam or other  similar  structure so located  in  the  outlet
of Lake  George  as to affect the  water levels of the lake shall,  with due
allowance for fluctuations due  to natural causes or to emergencies and
for a reasonable use of water for power  and for sanitary  purposes, be
operated in such a manner  as to maintain the waters  of the lake from
the first day of  June to the thirtieth  day  of September in  each year as
nearly as may be at an average  level of  three  and five-tenths  feet on
the gage of the  United States Geological Survey  at Rogers Rock on Lake
George,  known  as Rogers Rock  gage,  and in such a manner as to  main-
tain  the  waters  of the lake  from the  first  day of October to the first
day  of December at  a level which shall not fall below two  and five-
tenths feet on  said gage;  and,  consistent  with the above mentioned  fluc-
tuations and  reasonable use, the waste gates of any such dam  or  other
structure shall  be operated so that, to the  extent possible, the  waters
of the lake will  not be  permitted to rise  above a level of  four feet on
such  gage at any time during the year  or  to fall below a level  of two
and five-tenths  feet  on  said gage at any time after the first day of June
and prior to the first day of December in any year.   If at any  time
during the year  the waters  of  the lake  shall  rise above  such level  of
four feet any person owning or  operating  such dam or other structure
shall immediately open  the  waste gates thereof and take such  other
appropriate action as in the judgment  of the  superintendent of public
works may be  necessary  to lower the waters of the lake with the  least
practicable delay to  a level not  higher than four feet  on said gage.   If
at any time after the first day of June and prior to the  first day  of
December in any year the waters of  the lake shall fall below  such level

                                   143

-------
 of two  and five-tenths feet such person shall immediately close the
 waste gates of such dam or other structure; and no person shall  with-
 draw water from the lake for the purpose  of generating power during any
 period  of  time between the first  day of June and the first  day of  October
 in any  year when the level of the waters of the lake is below two and
 five-tenths feet  on  said  gage.   The  superintendent  of public works or his
 duly  authorized  representative shall at all  times  have access  to such dam
 or  other structure  and is hereby authorized and  directed to operate  the
 waste gates thereof whenever  necessary for the purpose  of carrying  out
 the provisions of this  section.   The  superintendent of public works shall
 establish such rules and regulations  as in  his judgment may be neces-
 sary  for the enforcement of the provisions of this  section,  and he is
 hereby authorized to enter into such agreement  or  agreements with any
 person or persons  owning or  operating any such dam or other structure
 as  in his  judgment may be necessary in order to carry into effect the
 provisions  of this  section and of  such  rules and  regulations.  In addition,
 the superintendent of public works  shall, once in each year during the
 first  week  in  July,   cause to be published  in at least three daily news-
 papers  serving the  area  the reading  on the Rogers Rock gage on  the
 first  day of July in  that  year.  Any  person violating any provision of
 this section or of any rule or regulation established  or of  any agreement
 entered into pursuant thereto  shall for every such  violation forfeit to
 the people  of the state  the sum of not  to exceed  two hundred  and  fifty
 dollars to be recovered in a civil action.

 Maximum  and Average  Depths - See  Table 5 (Colon,  1972;  Langmuir,
         et al.,  1966).

             Table 5.   MAXIMUM AND AVERAGE  DEPTHS
                      FOR LAKE GEORGE, N. Y.
          Basin
Maximum Depth
Aver a &e Depth
North
South
Total Lake
53.3 m (175 ft.)
58 m (191 ft.)
58 m (191 ft.)
20.5 m (67.3 ft.)
15.5 m (50.9 ft.)
18 m (59 ft.)
Location of Exceptional Depths  and the Surface Area  Ratio of  Deep to
Shallow Waters - These data are not available.
Ratio of Epilimnion over  Hypolimnion  -  These calculations  are not
         available.
Duration of Stratification  -  This phenomenon  occurs in Lake George for
         approximately 150 to 180  days (i.e.,  from May  1 through
         October 31).
                                   144

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Nature  of Lake Sediments

         Most of the sediments  of  Lake George consist of  silty clay;
pure  sand lies mostly  near the shore, yet most sand also contains silt
and clay in nearly equal amounts.   In the south basin sediments  con-
taining  more than  50 percent clay  occur near  the east  shore  and under-
lie  the  large central expanse of the lake.  Sediments with less than 25
percent clay (hence mostly sandy)  are restricted to the west  shore of
the south basin,  although in two places a tongue of sandy  sediment is
present in the  central  area of the  south basin.   Sediments underlying
the eastern Narrows are  rich in clay, whereas those beneath  the western
Narrows are generally  rich  in  sand.   The southern part of the north
basin is underlain by clay-rich sediments.   In  the central part of this
basin clay floors  the middle of the lake  and  sand is found closer to
shore.   In the northernmost part of the  north  basin,  near Ticonderoga,
the sediment consists mostly of sand  (See Figure 3).

         In the south basin most of the  bottom  sediments  contain  be-
tween 5  and  10 percent organic carbon.   However,  close to  and in bays
of the east  shore the organic carbon  content exceeds  10 percent.   By
contrast,  near the west shore and in  two tongues in the central part
of the south  basin the  organic carbon content is < 5 percent.    The
sediments of the Narrows  are mostly depleted in organic carbon, where-
as the sediments  of the north basin contain between  5 and 10  percent
organic carbon in the center, but  < 5 percent  near the shore.  Near
Ticonderoga  the  sediments of the northernmost part  of Lake George
contain  < 5  percent organic  carbon.   The muddy bottom sediments  of
Lake  Champlain,  contiguous  to  Lake George,  contain  5 to  20  percent
organic carbon; organic mud  covers  about three-quarters of  its bottom
(See Figure 4).

         Many values of organic carbon exceed  10 percent  and most
sediments contain between 5 and 10 percent  organic  carbon.    These
high values  indicate that a large part of the  clay-size fraction  consists
of organic  matter.  To compute organic matter from organic  carbon  a
factor of 1.72  is  used,  so that in  most  sediments  between 8.6 and 17.2
percent organic matter  is  present.   Examination under the binocular
microscope  shows  that the organic matter in the nearshore sediments
consists largely  of leaves, needles, tree bark, and spore  capsules.   In
deeper water  sediments, however,  the fabric of organic matter usually
cannot be identified because  of  advanced decomposition.  In the clay-
size fraction quartz and clay minerals including illite  and  chlorite with
traces of kaolinite are found.   In the cores  studied the same  clay-
mineral  suite occurs unchanged throughout the cores.   The clay is
derived from the  local metamorphic and igneous bedrock and  the  glacial
sediments.
                                   145

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                   -to Loke Chomptoin

               Tt'conderogo Creek
                        NORTH
                        LAKE
                        GEORGE
                            CLAY %
                                       FIGURE 3.    Clay

                                       Content Of  Lake  George

                                       Surface Sediments.
                       CZ3 25-50
                              >50

                          X SAMPLING STATIONS
LAKE
GEORGE
VILLAGE

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                    1o Loft* Chomplgin

                Ticondarogo Creak
                      NORTH

                      LAKE
                      GEORGE
                                   FIGURE 4.   Organic


                                   Carbon  Content of Lake

                                   George  Surface Sediments
                     ORGANIC CARBON %

                             <5

                            5-10
                     A, X SAMPLING STATIONS
Lake
Georg*
Villogt
                   147

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         In  the  sand the  light minerals  are quartz and feldspars
(plagioclase,  orthoclase),  some  microcline,  muscovite  and biotite.  The
heavy  mineral fraction is  dominated by garnet; less abundant heavy
minerals include  hornblende,  sillimanite,  epidote, hypersthene,  augite,
staurolite,  kyanite,  zoisite,  zircon,  tourmaline,  rutile,  titanite and
iron-rich biotite.

         Except at water-sediment interface  all sediment color  is  black.
There the color is either  black  or brown; the brown color of fine-
grained  sediment  passing downward into black.  Black  color at  the
interface dominates  near the  east shore in the south basin,  especially-
near  the  bays,  whereas  brown color is present near the west shore.

         The  sediments  in the Narrows and  contiguous areas consist  of
varved clay in which iron-manganese nodules  occur  (Schoettle and
Friedman,  1973).
Seasonal Variation of Monthly  Precipitation Together  With Maximum and
Minimum Conditions  on Drainage Basin -  See Tables 6a  and 6b (Colon,
         1972).
       Table 6a.  AVERAGE MONTHLY  PRECIPITATION FOR THE  SOUTH BASIN
                 (STATION 1),  LAKE GEORGE, N.Y.+
        Month
     Precipitation (Inches)

1969             1970
1971
January
February
March
April
May
June
July
August
September
October
November
December
0.083 (0.820)
0.041* (0.360)
0.050 (0.870)
0.136 (1.490)
0.137 (1.020)
0.104 (1.060)
0.112 (0.920)
0.078 (0.380)
0.052 (0.600)
0.042 (0.490)
0.175** (1.070)
0.081 (0.890)
0.021* (0.210)
0.082 (0.830)
0.078 (0.650)
0.058 (1.090)
0.074 (0.950)
0.065 (0.810)
0.095 (0.800)
0.067 (0.930)
0.138** (1.130)
0.092 (0.800)
0.106 (0.940)
0.115 (0.840)
0.052* (0.480)
0.158** (1.170)
0.127 (1.260)
0.087 (1.200)
0.070 (0,620)
0.053 (0.940)
-1.0
-1.0
-1.0
-UO
-1.0
-1.0
      The maximum precipitation value (inches) for each month is seen
      in parenthesis.   Missing  data are shown, as -1.0.  Annual mini-
      mum and maximum precipitation  values  are designated by an
      asterisk (*) and double asterisk (**)  respectively.
                                    148

-------
    Table 6b.   AVERAGE MONTHLY PRECIPITATION FOR THE
         NORTH BASIN (STATION 6), LAKE GEORGE, N. Y. +
                         Precipitation (Inches)
Month r 1969 1970 1971
January
February
March
April
May
June
July
August
September
October
November
December
-1.0
-1.0
-1.0
-1.0
-1.0
-1.0
-1.0
-1.0
-1.0
0.030* (0.400)
0.145 (0.860)
0.155** (0.860)
0.013* (0.120)
0.089 (0.930)
0.070 (0.600)
0.117 (1.770)
0.089 (1.090)
0.069 (0.680)
0.089 (1.090)
0.074 (1.240)
0.128** (0.980)
0.085 (0.650)
0.039 (0.270)
0.076 (0.710)
0.050* (0.500)
0.161** (1.180)
0.098 (0.710)
0.055 (0.710)
0.065 (0.560)
-1.0
-1.0
-1.0
-1.0
-1.0
-1.0
-1.0
  + The  maximum precipitation value  (inches) for  each month  is seen
    in parenthesis.   Missing data are shown as -1.0.  Annual mini-
    mum and maximum precipitation values  are designated by  an
    asterisk (*) and  double asterisk (**)  respectively.

Inflow  and Outflow of Water

         For the period of October,  1971 through May, 1972,  total
water  input to the lake  was 94.6 in-., losses were  86.5 in.  and a
storage  of 8. 1 in.  Groundwater for the  1971 water year is seen  in
Figure 5 (Colon,  1972).   Average outflow from, the lake at the north
(Ticonderoga) is 8.34 m^/sec., based on 22 years of record.
Water Currents - These data have not been determined.
Water Renewal  Time  -  Based on the volume and average outflow from
         the lake, the water  retention time in Lake George,  NY is
         7. 98  years.
                                   149

-------
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-------
IV.   LIMNOLOGICAL  CHARACTERIZATION (Preliminary)

Physical

1.   Temperature - See Figures 6, 7,  8,  and 9 (Williams and Clesceri,
     1972;  Colon,  1972).

2.   Conductivity -  These data available at this time  are from April
     through  September,  1971 and  ranged from  85-95 u mohs/cm.

3.   Light  transmittance  -  Light intensity  at the surface was 2,400  ft.
     candles  during  March,  1971 and  1972.  During August,  1971  and
     1972  the surface light intensity approached 6,000 ft. candles.
     Other data are shown  in Tables  7  and 8 (Williams and  Clesceri,
     1972).

4.   Color -  Measurements  of color  of  lake water have not  yet been
     determined for Lake George,  NY.

5.   Solar  Radiation  -  See  Figure 10  (Colon,  1972).


Chemical
1.  pH - See Table  9.

2.  Dissolved  oxygen - See  Table 10 (Williams &  Clesceri,  1972).

3.  Total phosphorus including  (fraction)  forms  -  See Table 11.

4.  Total nitrogen including  (fraction) forms  - See Tables  12  and 13.

5.  Alkalinity  -  See Table 14.

6.  Ca,  Mg,  Na, K, SO    Cl,  Fe  -  See Table  15 for  Fe;  insufficient
    data on others.  (Williams  and  Clesceri,   1972).

7.  Silica - See  Table 16.


Biological

1.  Phytoplankton
         a.   Chlorophyll  - These data are not available.
         b.  Primary production - See  Figure 12.   In addition,  data re-
            garding annual production of Nitella flexilis  (macroalga) and
             other  macrophytes  are given in  Table 17 (Stress,  1972).
         c.   Identification and count - Tables  18 and 19  (Howard, 1973)
             and Figure  11  (Williams and  Clesceri, 1972).

                                    151

-------
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-------
FIGURE 7. SEASONAL  CHANGES  IN  THE  LAKE  GEOR6C
        THERMOCLINE
       TEMPERATURE - DEGREES  CENT.'GRADE

      5»      10°      IS*      20*      2
30*
                         153

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-------
FIGURE 9.   Seasonal Variation  of Water  Temperatures at Diamond
              Island,  Lake George  (1972)
      DIAMOND ISLAND 1»72
— ,
31
Table 7.
59 90 120
TIME (DAYS OP VIA*)
SECCHI
DISC MEASUREMENTS
~l 	
151
(METERS)
— 1 	
181

	 1 	
212

                                                                       243
                Date
Station 1   Station 6
3/26/70
6/26/70
7/17/70
8/16/70
9/28/70
0/05/70
O/il/70
1.08/70
7.0
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9.5
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9.0
10.0
                                155

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-------
         TABLE 12
TOTAL KJELDAHL N (mg N/l)
Station 1
Pate

73.065
73.186
73.199
73.213
73.241
73.255
73.269
73.304
73.324
Station 6
Date

73.186
73.199
73.241
73.255
73.269


73.324
Station 1 :
Station 6:


0.5
0.218
0.212
0.176

0.230
0.324
0.195
0.267
0.178


0.5
0.101
0.193
0.1?8
0.251
0.199


0.173
Range:
Range :


5.0
0.237
0.220
0.260
0.302
0.146
0.312
0.277
0.230
0.205


5.0
0.062
0.212
0.170
0.246
0.191


0.186
0.130-0.314
0.062r0.343

Depth
10.0
0.187
0.208
0.269

0.132
0.248
0.235
0.266
0.202

Depth
10.0
0.086
0.196
0.105
0.249
0.191


0.175



(»)
15.0
0.157
0.179
0.186
0.236
0.168
0.309
0.216
0.245
0.247

(m)
15.0
0.138
0.269
0.107
0.100
0.190


0.177
Mean: 0
Mean : 0


20.0
0.198(21m)
0.130
0.202
0.167
0.189
0.240
0.202
0.221
0.185


20.0
0*127
0.343
0.137

0.207


0.197
.219 ± 0.046
.198 + 0.141


23.0







0.203



25.0


0.102

0.208
0.200(30)
0.206(35)



             160

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Table 14.   ALKALINITY (mg CaCOj/l)  FOR  LAKE GEORGE,  N. Y.
        Date
Average Alkalinity (mg  CaCO3/l)
 North Basin      South Basin
        July,  1972
        August,  1972
        September,  1972
        October,  1972
        November,  1972
        March,  1973
        April,  1973
        May,  1973
        June,  1973
        July,  1973
        August,  1973
        September,  1973
        October,  1973
        November,  1973
        December,  1973
        January,  1974
      23.0
      16.95
      17.5
      22.6
      23.4
      22.0
      22.5
      21.7
      21.5
      21.6
      20.8

      24. 1
22.4
16.7
16.5
22.1
23.6
22.8
22.6

23.2
22.6
21.9
21.4

21.3
                                162

-------
       Table-15-  MEAN SEASONAL CONCENTRATIONS OF FE, MN, CU AND

         ZN IN THE NORTH AND SOUTH BASINS OF LAKE GEORGE, N.Y.
Season
Winter
(Jan. l-Mar.31)
Spring
(Apr.1-June 21)
Summer
(June 21-Sept.2l)
Fall
 (Sept.21-Dec.  7)
Depth(m)

   3

   9

  15



   3

   9

  15



   3

   9

  15



   3

   9

  15
 South Basin (ug/1)    North Basin (ug/l)

 Fe    Mn   Gu   Zn    Fe    Mh   Cu   Zn

27.2  2.0  5.2  U3.U  35.2  1.9  2.7  51.1

U2.1  2.1  3.5  ^9.3  3^.8  1.3  2.0  79.6

30.6  1.6  3.7  Mf.U  50.7  2.3  2.2  76.6



25.1  3.2  3-9  32.7  kl.5  2.9  2.6  33.5

17.3  2.5  *».2  28.0  26.2  2.5  3-5  53.2

16.9  i+.o  3.8  30.^  35.^  3.2  3-2  38.6



29.0  2.6  3.^  U6.4  29.8  2.0  3-0  7^.9

23.5  2.2  3.1  31.8  23.8  3.3  3-2  ko.h

28.8  U.i  2.9  3^.2  23.6  1.9  2.9  23-9



U6.1  1.8  3.1  25.1  13.8  l.h  1.6  71.1

39.9  1.7  2.5  23.3  20.5  1.2  1.7  88.3

30.3  2.5  2.6  1+3.5  1^.5  1.1  2.0  7^.5
                                   163

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                                FIGURE   11
                                STATION I
                                              TOTAL PLANKTON DIATOMS
0»V  M tl M M » II M I* II M T  I  2i IT St M H IS to II II •  7 •  7  tT M M M
          FIGURE 12.  Mean Daily Rates of Phytoplankton Photosynthesis
       JASON  D\JFMAMJJAS  OND\JFMAMJJA
           1970                       1971                      i9"'2
                                       165

-------
Table  17.   ANNUAL PRODUCTION OF Nitella flexilis AND  OTHER
            MACROPHYTES IN THE SOUTH BASIN OF  LAKE GEORGE,
            N. Y. FOR  THE YEAR 1972.   ALL MEASUREMENTS ARE
            IN GRAMS  (dry wt. )/m2± STANDARD ERROR (Stress,
            1972),
  Depth         Nitella flexilis
.(meters)   	June           Sept.
Other Sepcies
    Sept.
  Annual
Production
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
11.0
12.0




16.41 + 2.3
30.42 + 7.9
44. 06 + 5. 1
57.69 ±5.0
57.83 + 5.1
57.91 + 5.2



43.79 ± 10. 1
53.68 + 19.8
73.48 + 31.5
76.93 + 16.55
133.00 + 39.3
53.39 + 34.4
105.96 + 36.9
97.65 + 28.0
95.10 + 31.8
39.38 + 31.6
42.42 ± 15.9
32.95 + 18. 1
3.67 + 3.5




97.65 ± 28.0
95.10 ± 3.18
39.38 + 31.6
130.00 ± 26.0
103.04 + 40.2
107.57 + 42.9
120.99 ± 21.6
190.69 + 43.3
111.22 + 39.5
163.93 + 43.1
                                 166

-------
         Table  18.  SPECIES FOUND IN LAKE GEORGE
                       PHYTOPLANKTON
Ne:  net plankton  (maximum dimension  greater than 50 u)
Na:  nannoplankton (maximum  dimension 50 u or less)
 *•  Eudorina elegans Ehrenberg.   (Na)
 2«  Sphaerocystis Schroeteri  (Wolle) W.  & G.  S.  West.  (Na)
 3.  Gloeocystis gigag  (Kuetzing) Lagerheim.  (Na)
 4.  Elakatothrix  gelatinosa Wille.  (Na)
 5.  Planktosphaeria gelatinosa G.  M.  Smith.  (Na)
 k«  Oocystis crassa Wittrock. (Na)
 '•  Qocystis pusilla Hansgirg.   (Na)
 8*  Oocystis sub marina Lagerheim.   (Na)
 9.  Oocystis sp.   (Na)
10.  Botryo coccus braunii Kuetzing.  (Na)
11.  Dimorphococcus lunatus A. Braun.  (Na)
12.  Ankistrpdesmus falcatue  (Corda) Ralfs var. acicularis (A.
     Braun)  G.  S. West.   (Na)
13.  Selena strum minutum (Naeg.)  Collins.  (Na)
14«  Quadrigula closterioides  (Bohlin)  Printz.   (Na)
15«  Tetraedron minimum.  (A. Braun)  Hansgirg.   (Na)
16.  Scenedesmus  bijuga (Turp.) Lagerheim.   (Na)
17.  Crucigenia rectangularia  (A.  Braun) Gay.   (Na)
18«  Crucigenia tetrapaedia (Kirch.) W. &  G.  S.  West.   (Na)
19.  Cosmarium sp. (Na)
20.  Cosmarium sp. (Na)
21.  Staurastrum furcigerum  De  Brebisson.
22.  Spondylosium planum (Wolle) W.  & G.  S.  West.   (Ne)
23.  Tribonema sp.  (Ne)
24.  Ochromonas  sp.   (Na)
2s*  Bitrichia chodati  (Reverdin) Chodat.   (Na)
26.  Dinobryon bavaracum Imhof.  (Na)
27.  Dinobryon cylindricum Imhof.  (Na)
28.  Dinobryon divergens Imhof.   (Na)

                                   167

-------
 Table 18 (Continued).   SPECIES FOUND IN LAKE GEORGE
                           PHYTOPLANKTON
29.  Epipyxis sp.   (Na)
30.  Mallomonas sp.   (Na)
31.  Mallomonas ap.   (Na)
iz.  Melosira sp.   (Ne)
33.  Cyclotella  comta  (Ehren.) Kuetzing.  (Na)
34-  Cyclotella  stelligera  Clet & Grunow.   (Na)
35.  Stephanodiscus astrea (Ehren.) Grunow.   (Na)
36.  Tabellaria  fenestrata (Lyngb.) Kuetzing.   (Na)
37.  Meridion circulare (Grev.) Agardh.  (Na)
38.  Fragilaria  crotonensis  Kitton.  (Ne)
39.  Asterionella formosa Rassall.  (Ne)
40.  Synedra sp.   (Ne)
41.  Gymnodinium  sp.   (Ne)
42.  Glenodinium pulvieculus  (Ehren. ) Stein.   (Na)
43.  Peridinium cinctum (Muell.)  Ehrenberg.   (Ne)
44.  Cryptomonas  sp.   (Na)
45.  Chroococcus dispersus (Keissl.) Lemmermann.   (Na)
46.  ChroQcocciis limneticus Lemmermann.   (Na)
47.  Gloeocapsa pun eta ta  Naegeli.   (Na)
48.  Aphanocapsa elachista  West and West.   (Na)
49.  Mjcrocystis incerta Lemmermann.   (Na)
50.  Gloethece  linearis Naegeli var.  compoeita G. M.  Smith,   (Na)
51.  Aphanothece clathrata G.  S.  West.  (Na)
52.  Aphanothece nidulans P.  Richter.   (Na)
53.  Cocloaphaerivim Naegelianum Unger.   (Na)
54.  Gomphognhaeria apopina  Kuetzing.   (Na)
55.  Lyngbya limnetica Lemmermann.   (Ne)
56.  Anabaena sp.   (Na)
57.  -   64.,  Unknown  coccoid cells and flagellates.  All (Na)
                                168

-------
                            TABLE 19

            PHYTOPLANKTON BIOMASS IN LAKE GEORGE
   All data collected at Station 1 and reported as micrograms
per liter*.
DATE
DEPTH
(m)
0.5
2.0
5.0
10.0
15.0
72.257

144.

188.
631.
271.
.307 73.

11.0

11.0
5.60

065

10,0
51.0
124.
80.0
103.
.107

511.
758.
558.
531.
721.
.186

325.
129.
261.
190.
188.
.216

189.
461.
260.

260.
.241

79.0
72.0
131.
126.
106.
                               o
* Assuming a density of 1 gm/cm


Data from Howard (1973)
                                169

-------
2.   Zooplankton  (McNaught,  et  al. ,  1972)
        a.   Identification and count  -
                  Species                      Numb e r / m^ / day
             Diaptomus  sicilis                       961
             Diaptomus  minutus                    2554
             Cyclops bicuspidetus                  3737
             Daphnia galeata                        714
             Daphnia longiremus                    212
             Bosmina spp.                           358

3.   Bottom Fauna - See Table  20 (Perrotte,  1974).

4.   Fish  -  The data shown in  Table 21 are  from  1973  surveys of the
    littoral region (15 sites) of  Lake George.   There are no census
    figures, etc.  for the fish populations of the entire  lake.   Of major
    importance to this trophic level and yet not included herein due to
    a lack  of reliable  figures at  this time are  the  Cisco and Lake trout
    populations for this  body of water (George,  et  al. ,  1974).

5.   Bacteria  -  The organisms listed are  the most  abundant  bacteria
    observed in  Lake George,  NY:
             Achromobacter  spp.
             Aeromonas  liquefaciens
             Aeromonas  spp.
             Arthrobacter spp.
             Brevibacterium haelis
             Brevibacterium sp.
             Cellulomonas  sp.
             Kurthia sp.
             Proteus sp.
             Pseudomonas  cohaerens
             Pseudomonas  spp.

6.   Bottom flora  - These  data  have not yet  been determined.

7.   Macrophytes  -  See  Table 22  (Boylen  and Sheldon,  1973).
V.   NUTRIENT BUDGETS - See Table  23.
                                    170

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                                                      172

-------
   Table 22.   MOST COMMON MACROPHYTE SPECIES  FOUND
      IN THE LITTORAL ZONE OF LAKE  GEORGE,  N. Y. *

Average Dry
Weight of
_ Species mature plant"*"
Bid en s beckii
Char a globularis
Elatine minima
Elodea canadensis
Eriocaulon septangular e
Heter anther a dubia
la oetes echinospora
Isoetes macrospora
Juncus sp.
Lobelia dortmanna
Myriophyllum alterniflorum
Myriophyllum ten ell urn.
Naias flexilis
Nitslla flexilis
Potamogeton amplifolius
Potamogeton gramineus
Potamogeton perfoliatus
Potamogeton praelongus
Pptampgeton pusillus
Potarn octet on robbinsii
Ranunculus longirostris
Sagittaria sp.
Utricularia resupinata
Vallisneria americana
Subularia sp.
.483 g
.075 g
.540 g
.237 g
.947 g
.268 g
080 g
2.677 g
.307 g
.284 g
.836 g
.081 g
.873 g
.154 g
.394 g

.536 g
.014 g
Average Maxi-
mum Height of
mature plant
56.3 cm
12 cm
60 cm
2.8 cm
84 cm
51.3 cm
24 cm
75.7 cm
84 cm
74. 5 cm
73.3 cm
29. 3 cm
69. 7 cm
«
46 cm
11 cm

77.7 cm
6.2 cm
Depth of
maximum
abundance
2-7 m
1 m
1 m
1-9 m
1 m
1-3 m
1-3 m
3-8 m
1 m
1 m
1-3 m
1 m
1-7 m
9 m
3 m
1-5 m
1-5 m
5 m
2-5 m
7 m
1-3 m
1 m
1 m
1-5 m
1 m
** All species collected from 1 m depth or greater.  All were sub-
  mergent.
+ Plants were collected on 8/30/73.   Visual observation suggests
  that plants  collected were  smaller than mature  plants found earlier
  in the summer.

                                   173

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                        TABLE 23

       Estimated  Phosphorus and Nitrogen Budget
         Based  on  Normal Precipitation of Basin
Phosphorus
Sources
Runoff
Precipitation
Sewage Treat-
ment Plant
Effluents
Septic tank
Effluents
Lawn Fertilizer
Total

Sinks
Outflow at
Ticonderoga
Sedimentation
kg
2890
2400

0

2300
208
7800


2040
5760
% of Total
Sources
37.1
30.8

0

29.5
2.6
100
% of Total
Sinks
26.2 *
73.8
Nitrogen
ko
86,700
84,600

18.OOU

9,580
2,080
201,000


62 , 800
138,000
% of Total
Sources
43.1
42.1

9.1

4.8
1.0
10.0
% of Total
Sinks
31.2
68.8
Retention                   73.8

Surface loading 0.0684 g/m /yr
                                                    68.8
                                          1.76
(From Gibble, 1974)
                             174

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VI.  DISCUSSION

         The geologic history of Lake George appears  to  be  the  primary
element  in the present trophic  status of the lake.   Lying essentially
in a long narrow channel bordered by heights reaching in excess of 600
meters above the lake surface, the ratio of drainage basin  surface area
to lake surface area is only 4.3.  The bedrock  is precambrian  meta-
morphic,  plutonic and  igneous and lies  close to  the  surface  with numerou:
outcroppings in the  basin.   Thus,  only  a thin soil cover  overlies much
of the  basin.   Precipitation is  the only form of  hydrologic import,  and
the basin represents a headwater for the Lake Champlain catchment area.

         If one can  assume  that  15%  of  the  Lake George basin is repre-
sented by cleared lands,  regardless  of  purpose,  then  the export  of
phosphorus,  calculated from runoff loadings (Gibble, 1974) would be
6.9 mg/m /yr.  This  figure  lies within the range of estimates presented
by Dillon and Kirchner (1975)  for forested  land  overlying igneous rock.
The  latter category corresponds to Vollenweider's (1968)  classification
of "oligotrophic" soils.  Apparently, phosphorus exports  in the  Lake
George watershed are  typical for this type  of soil-vegetation cover.

         The small  basin to lake area  ratio emphasizes the importance
of precipitation directly upon the lake  surface as a  source of  N and P
loadings  to  Lake George.   Combined with runoff, these two  sources
account for 68 and  85% of the phosphorus and nitrogen loadings, respec-
tively.  Anthropogenic phosphorus  sources  are already reduced through
application of treated sewage effluent (from the  Lake George Village
area) onto sand beds,  and adsorption onto  soils  in the numerous septic
tank tile fields.   There are no known  sources of untreated  sewage  into
the lake.

         Having recognized the need  for  a relatively  simple approach
to the  classification of the productivity  or trophic  state of lakes,
Vollenweider (1968) and Vollenweider and Dillon  (1974) have  concentrated
their attention  upon phosphorus as the  limiting element.   However,
recognizing that  as  a limiting  element  its concentration in the water
column would simply  represent a "residual, " they have focused  on  the
importation,  or phosphorus  loading,  as the proper relationship to pro-
ductivity.   Internal loading or recycling must also  be considered,
especially in small  lakes,  but external  loading is more important in the
larger lakes (Vollenweider,   1968).

         The lake volume to phosphorus  loading  relationship  was  original-
ly taking into account through the mean  depth of the lake.  However,
recognizing that  retention time  was equally significant, Vollenweider and
Dillon  (1974) regressed phosphorus loading  against an  areal  water loading,
expressed as  mean  depth divided by  mean residence time.   The  new
relationship provides  a significantly  better  fit for lakes in which mean
                                    175

-------
detention times are  within very long,  e. g. ,  Lake Tahoe,  or very  short
as  is the case  of  some  Canadian Shield lakes.

         Referring to the nutrient budget  for  Lake George (Gibble,  1974),
the estimated phosphorus loading is 0.0684 gm/m /yr. (See  Table 23).
With a mean depth of  18  meters and a mean  retention  time of 8 years,
Lake George can  be  classified  as "oligotrophic" on this basis.

         Aulenbach and Clesceri (1973) have emphasized the fact,  how-
ever,  that  Lake George consists of two distinct basins, south and  north.
The lake surface area  and  drainage basin area are  57.6 km  and  313.2
km  for the south basin and  56.4  km^ and 178.8 km^  for the north
basin.    The year-round population  in  the  south basin is approximately
four times  that of the north,  but during the summer season,  this
figure  increases to approximately  six times.   Additionally,  the south
basin contains the two  sewage  treatment  plants located within the total
watershed.

         Using proportional estimates,  the phosphorus loading to the
south basin would be 0.0908  gm/m^/yr.   With a mean depth  of 15.5
meters and assuming the same  mean  retention time of 8 years,  the
south basin would still lie within the  "oligotrophic"  classification.
The similarity  of  the phosphorus loading to  the south basin and to the
total lake,  once again points  to the importance of direct precipitation
to the  lake surface as  a  nutrient source.

         The correctness of the loading approach to determine produc-
tivity,  at least as it applies  to  Lake  George,  is  borne out by the  rela-
tive success of the process  model  CLEANX which  describes the pelagic
epilimnetic zone  (Scavia, 1975;  Bloomfield,  et  al. ,  1973).     The  com-
partments represented  are  the  net- and nannophytoplankton, herbivorous
and omnivorous  zooplankton,  non-piscivorous and piscivorous  fish,
particulate  and dissolved organic matter,  dissolved  inorganic  nutrients
and decomposers.  The driving functions  are the phosphorus,  nitrogen
and carbon inputs  from streams, as well as  water temperature, inci-
dent solar  radiation  and the level  of benthic  insect biomass.

         The basic processes are obvious but also  factual.   High  spring
nutrient  loadings,  abetted by  winter thaws, in the presence of rising
temperature and  solar  radiation levels, result  in a  pulse  of phyto-
plankton biomass, principally the net  plankton, Asterionella formosa.
Available dissolved nutrients  are further increased by  decomposer activ-
ity upon organic matter in  the  runoff.  Mean daily production rises  to
1.5 gm  C/m^/dy  or higher (Figure 12).   Zooplankton predation follows
with Cyclops  bicuspidatus,  as a principal species.   Cropping  by the
non-piscivores  reduces pressure upon  the phytoplankton,  but in the
presence of lower summer concentrations of nutrients,  the  nannoplankton
become  dominant  (in  terms of  biomass,  Cyclotella compta  becomes  the
                                    176

-------
principal species).   A biomass and phytoplankton production pulse again
occurs in the August-September period.   This pulse precedes turnover
in Lake George,  and is  therefore  probably  unrelated to nutrient in-
creases from the hypolimnion.

        In Figures  13,  14  and 15  observed levels of biomass are
compared with those sirrmlated by  the model.  The reasonable fit of
the simulation  indicates  that the modeling of the ecologic  processes is
sound, and that nutrient inputs from  streams with subsequent internal
recycling are the principal non-physical  driving  forces in the Lake
George  ecosystem.

      100.0'
       10.0-
        1.0-
s
x
w
T>
01
in

S
O
3
        0.1
       0.01-
      0.001'
                                              A
                                         AA  A
                                                         A
                               141
                                      DAY
                                             281
365
     FIGURE 13.
             Predicted  and Observed Biomass Levels of
             Cladocerans and Copepods  in Lake George.
             Observed Values are from  McNaught,  et al. (1972)
             ^  « copepods,  Jt  »  cladocerans
                                  177

-------
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-------
                             REFERENCES
Aulenbach,  D.  B., and  N.  L.  Clesceri.   Sources and Sinks of Nitrogen
        and Phosphorus:  Water Quality Management of  Lake George
        (NY).   In:  G.  F.  Bennett (ed. ).    Water -  1972.   69(129).
        AIChE.   1972.

Aulenbach,  D.  B., and  N.  L.  Clesceri.   Sources of Nitrogen and
        Phosphorus in the  Lake George Drainage Basin:  A Double
        Lake.   In;   Proceedings of the 19th Annual Meeting,  Institute
        of Environmental Sciences.   Fresh Water Institute  Report
        No. 73-1.  1973.

Bloomfield,  J.  A., R. A.  Park,  Don Scavia,  and C. S.  Zahorcak.
        Aquatic Modeling in the Eastern Deciduous Forest  Biome, U. S.
        International Biological Program.   In:  Modeling the Eutrophi-
        cation  Process, Workshop  Proceedings (E. J. Middlebrook,  ed.)
        Utah Water Research Lab.,  Utah  State Univ., Logan, Utah.
        1973.

Boylen, C.  W.,  and R. B. Sheldon.   Biomass Distribution  of Rooted
        Macrophytes in the Littoral  Zone  of Lake George.   Eastern
        Deciduous Forest  Biome,  International Biological Program,
        Oak Ridge, Tennessee.  EDFB-IBP Memo Report  73-65.
        Fresh Water  Institute  Report No.  73-21.   1973.

Colon,  E.  M.   Hydrologic  Study  of Lake George,  New  York.  D.  Eng.
        Thesis.   Rensselaer Polytechnic Institute,  Troy, NY  1972.

Dillon,  P.  J.,  and W.  B.  Kirchner.  The Effects  of Geology and Land
        Use on the Export of Phosphorus  from Watersheds.   Water
        Res.   £, P-  135-148.   1975.

George, C., P.  W.  Briddell,  and  J.  H.  Gordon.   Notes on the
        Centrarchids  of Lake George,  NY.   Eastern Deciduous Forest
        Biome,  International Biological Program, Oak Ridge, Tennessee,
        EDFB-IBP Memo Report No. 73-72.  Fresh Water Institute
        Report No. 73-24.   1974.

Gibble, E.  B.    Phosphorus and Nitrogen Loading and Nutrient Budget
        on  Lake George,  NY.  M.  Eng.  Thesis, Rensselaer Polytechnic
        Institute, Troy, NY.   1974.

Howard, H. H.  Phytoplankton in  the Lake George Ecosystem.  Eastern
        Deciduous Forest  Biome,  International Biological Program,  Oak
        Ridge  Tennessee.   EDFB-IBP Memo Report No. 73-71.   1973.

                                   179

-------
Langmuir, I. (Posth. ),  J. T.  Scott,  E. G.  Walther,  R.  Stewart and
         W.  X.  Rozon.   Langmuir Circulations and Internal Waves in
         Lake George.   Atm. Sciences  Res.  Center,  SUNY-Albany,
         N. Y.   Publication No.  42.   1966.

McNaught, D.  C. ,  K.  Bogdan,  and J.  O'Malley.  Zooplankton Community
         Structure and  Feeding Related  to Productivity.  Eastern Decidu-
         ous  Forest  Biome,  International Biological Program,  Oak Ridge,
         Tennessee.   EDFB-IBP Memo Report No.  72-69.   1972.

Nicholson, S. ,  and J.  T.  Scott.   A Sample  of the Vegetation  in the  Lake
         George Drainage Basin:  Part  II.    Composition of the Canopy
         Vegetation and some Aspects  of Physiographic and Horizontal
         Variation Within  the Basin.   Eastern  Deciduous Forest Biome,
         International Biological Program,  Oak Ridge, Tennessee.
         EDFB-IBP Memo Report No.  73-8.    1972.

Perrotte,  W. T.   In preparation.   1975.

Scavia, Don.  Implementation  of a Pelagic  Ecosystem Model for Lakes.
         Masters  Thesis.   Rensselaer Polytechnic Institute,  Troy,  New
         York.

Schoettle,  M. ,  and G.  M. Friedman.   Sediments and Sedimentation in
         a Glacial Lake:  Lake  George,  N. Y.   Eastern Deciduous Forest
         Biome,  International Biological Program, Oak Ridge,  Tennessee.
         EDFB-IBP Memo Report No.  71-122.   Fresh Water Institute
         Report No.  72-11B.   1971.

Schoettle,  M. ,  and G.  M. Friedman.   Organic  Carbon in Sediments in
         Lake George,  NY:  Relation  to Morphology  of Lake Bottom,
         Grain Size of Sediments,  and Man's  Activities.   Eastern Decidu-
         ous  Forest  Biome,  International Biological Program,  Oak Ridge,
         Tennessee.   Contribution  No.  36.  Fresh Water Institute Report
         No.  73-9.   Geol. Soc. of Amer.   Bull.  84:  191-198.   1973.

Stewart,  R.   Contributions to the  International Biological Program  -
         Year I.   Eastern Deciduous  Forest Biome,   International  Bio-
         logical Program,  Oak Ridge,  Tennessee.  EDFB-IBP  Memo
         Report No.  71-124.    1971.

Stewart,  R.   Contributions to the  International Biological Program  -
         Year II.   Eastern Deciduous Forest  Biome,  International Bio-
         logical Program,  Oak Ridge,  Tennessee.  EDFB-IBP  Memo
         Report No.  72-71.   1972.

Stress,  R. G.  Primary Productivity of Lake George, NY:  Its Estimation
         and Regulation.  Eastern  Deciduous Forest Biome, International
         Biological Program, Oak  Ridge, Tennessee.  EDFB-IBP Memo
         Report No.  72-72.   1972.

                                    180

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Vollenweider, R.  A.  Scientific Fundamentals of the Eutrophication  of
         Lakes and Flowing Waters, with Particular Reference to  Nitrogen
         and  Phosphorus  as Factors in Eutrophication.   Organization for
         Economic  Cooperation and Development.   Directorate for  Scien-
         tific Affairs.   Paris,  France.  1968.

Vollenweider, R.  A., and  P. J. Dillon.   The Application of the Phos-
         phorus  Loading  Concept to Eutrophication Research.   Nat'l.
         Res. Council Canada Rept.  No.  13690 (1974).

Water Resources  Commission.  Classification and Standards  of  Quality
         and  Purity of Waters of New York  State.  Parts  700-703.
         Title 6.   Official  Compilation of codes,  rules,  and regulations
         prepared  and published for the Water Resources Commission
         by the New York State  Department  of Health.   November,
         1968.

Williams, S.  L.,  D. B.  Aulenbach,  and  N. L.  Clesceri.   Transition
         Metals  and Zinc in the Aquatic Environment.   In;  Alan Rubin
         (ed.) Aqueous-Environmental  Chemistry of Metals.  Ann Arbor
         Science Publishers,  Inc.  Ann Arbor,  MI.  1974.

Williams, S.  L.,  and N.  L.  Clesceri  (eds.) Diatom Populations
         Changes in Lake George,  NY  Final Report for US Dept.  of
         Interior,  Office  of Water  Resources Research  Contract  No.
         14-31-0001-3387.  Fresh  Water Institute Reports  No. 72-1
         thru 72-8.   1972.
                                   181

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                   THE LIMNOLOGY OF CAYUGA LAKE,  NEW YORK

                                - A SUMMARY -


                               Ray T.  Oglesby
                      Department of Natural Resources
            N.Y. State College of Agriculture and Life Sciences
                             Cornell University
                              Ithaca, New York


     The Indians who lived in villages around the lake called it "Tiohero,"
the lake of flags or rushes or lake of the marsh.  The first white man known
to have visited its shores was a Jesuit priest whose journal (Raffieux,
1671-72) described the members of the Cayuga tribe as accomplished agricul-
turalists, fishermen, and hunters.  They had probably modified the land
extensively by annual burnings (Dudley, 1886; Thompson, 1972) as evidenced
by the "almost continuous plains bordered by beautiful forests" observed by
Raffieux at the northern end of the lake.

     The orchards and fields of the Indians were laid waste by the punitive
expedition under Sullivan during the War of the American Revolution.  Ten
years later the first white settlement, Ithaca, was started at the south end
of the lake which by then was called Cayuga after its earlier inhabitants.
A large influx of settlers followed the connection of Cayuga Lake to the Erie
Barge Canal in 1821 and the completion of a lock in 1829 (Whitford, 1906).

     The 1800's witnessed the growth of numerous small industries in the
Ithaca area as the ready sources of power and water represented by the larger
steep gradient streams such as Fall Creek were exploited (Anonymous, 1879).
The basin was also heavily agriculturalized and as much as 80%vof the land
area may have been under cultivation by the turn of the century.  Soil erosion
must have reached massive proportions during periods of heavy runoff.

     The development of the Appalachian coal fields, railroads and the
exploitation of fertile prairie soils in the Midwest dictated a rapid decline
in both industry and farming with a major abandonment of land taking place
under Federal programs to combat rural poverty in the late 1920fs and early
1930's.
                                     182

-------
                               GEOGRAPEY





     Cayuga Lake is located (intersection of longitudinal and cross axes)



at 40°41'30" N and 76°41'20" W at an altitude of 116.4 m (382 ft) above sea



level (Greeson and Williams, 1970). Its catchment area (including lake sur-


                 2        2
face) is 2,033 km  (785 mi ) according to the U. S. Department of the



Interior (1971).



     The climate is of the humid continental type with warm summers and long,



cold winters.  The area lies on the main west to east track of cyclonic storms



and hence its weather is highly variable and is characterized by considerable



cloudiness.  Annual precipitation ranges from 71-117 cm (28-46 in) with half



of this normally falling from May through September.  Seasonal changes (from



Dethier and Pack, 1963) in several climatological properties are shown in



Figure 1.  Cayuga Lake has been frozen over its entire length during at least



ten winters since 1796.  Typically, however, sheets of ice extend out from



the north and south ends only to about the 5-10 m depth contours with maximum



coverage in February.



     The bedrock of the basin consists mostly of acid shale and sandstone but



is intersected by two major limestone formations (Rickard and Fisher, 1970).



Outcroppings of the southernmost formation extend to nearly the head end of



the lake.  The soils of the northern two-thirds of the Cayuga basin are



dominated by moderately coarse textured types with calcareous substrata.



Those of the major tributaries and highlands surrounding the southern part



of the basin are composed of a diverse and complex assemblage and, in general,



are less well drained and more acid (Cline and Arnold, 1970).



     Cayuga Lake is located in an elongated, glaciated basin that opens into



rather flat terrain at its north end but becomes progressively steeper towards



the south.  On the east side of the lake this rise becomes an obvious feature


                                183

-------
         I6r
          14-
                      EVAPORATION

                     SOLAR  RADIATION
            -  25r
            -  20
I80i-



150
C\P
~0
°I20
E
C7>

Z
Q Q/~\
P
5

cr
<6°
o

30


0



-


_







,_,
V.
JC
-^20
i—
o
-oio
UJ
o
Li o
12
E
u
O
blO
cr
o
Q.
>
3
z

z
o

^6
Q.
O
UJ
ce.
_ Q. 4


- -2


- 0
- 2



- 2


- ^_^
o
0
*— '
UJ
cr
i>
~s
cr
UJ
Q.
ill
UJ


-


_ •
            -   0
            L  -5
                                            WIND VELOCITY
CQ
UJ
u.
                              QC
                              <
cr
a.
O    Q.
ID    UJ
<    cn
                                                                o
                                                                o
o
u
UJ
Q
Figure 1.  Monthly mean values for solar radiation, wind velocity, precipitation,

          evaporation and temperature at Ithaca,  New York.
                                  184

-------
about one-third of the lake's length from its northern terminus and a



similar increase in elevation occurs on the west side slightly further to



the south.  The upland plateau at the southern end is at an elevation of



250-300 m (800-1,000 ft) with the hills beyond occasionally extending to



about 600 m (2,000 ft).



     The dominant tree association in the northern one-fourth of the basin



is elm-ash-red maple.  The remainder of the lake border and the valleys



are dominated by oak and hickory while the upland association is mainly



beech-hard maple.  Forage crops constitute the principal vegetation



associated with agriculture.  Child, Oglesby and Raymond (1971) determined


                                 2                                   2
the 1968 land usage to be: 904 km  (48.3%) active agriculture, 292 km


                                    2
(15.6%) inactive agriculture, 582 km  (3%) of the usage falls into other



categories such as transportation and mining.  Using data from the 1970



census (U. S.  Bureau of the Census 1970a and 1970b) the population of the



basin is calculated to be 90,221.



     Cayuga Lake serves as a supply of potable water for five towns or



villages in the basin and an additional, combined supply for three other



towns is under development.  Water supplied to the major population center



(City of Ithaca) in the basin comes from an impounded upland source.  A



435 MWe fossil fueled power plant currently takes its cooling water from the



lake and a second such facility, almost double in size, is under consideration.



Cayuga Lake is extensively used for fishing, boating and swimming.  Three



state, one city and one town park are located on its shoreline.



     Industrial wastes discharged to Cayuga Lake tributaries are in excess



of 5,109 m3 (1,350,000 gal) day" .  All are treated at the industrial sites



prior to discharge and/or are put into the sanitary sewer system of Ithaca.



In the past, large quantities of NaCl entered the lake as runoff from the


                                185

-------
site of a rock salt mine.  Municipal waste is discharged to the lake at the



rate of 23,881 m  (6.3 mg) day"  with all but about 1% receiving at least



secondary treatment.  Additional treatment for phosphorus removal is, or


                                 3    -1
will shortly be, given to 3,369 m  day   (14%) of the sewage being discharged.
               MORPHOMETRIC AND HYDROLOGIC CHARACTERISTICS





     Cayuga Lake has a simple eavestrough shaped basin with the steepest



dropoffs and greatest depths occurring in the southern two-thirds of its



length.  Morphometric properties according to Birge and Juday (1914) are:



172.1 km2 (66.4 mi2) surface area, 61.4 km (38.1 mi) length, 5.60 km (3.50 mi)



maximum width, 2.80 km (1.74 mi) average width, 153.4 km (95.3 mi) shoreline



length, 3.35 shoreline development, 9,379.4 X 10~6 m3 (331,080 X 10~6 ft3)



volume, 132.6 m (435 ft) maximum depth, 54.5 m (172.3 ft) mean depth, and 1.23



volume development.  Their calculations indicate that a plane at the 40.3 m



depth would divide the lake into two equal volumes.



     The water level in Cayuga Lake is regulated by Mud Lock at the north



end.  The lake level is generally lowered by drawdown about mid-December and



is again raised in the spring by input from snowmelt and rain.  A maximum



recorded lake level of 117.7 m (386 ft) occurred following Tropical Storm



Agnes in 1972.



     Using the data of Singley (1973) it can be seen that for 1950-52 and



1968-72 the relative volumes of the various thermal strata underwent a complex



pattern of change over the stratified season (Figure 2).  Three periods of



downmixing and two when the relative volumes of the thermal strata remained



constant are apparent.  Duration of stratification is discussed below.



     Sediments in the profundal zone of Cayuga Lake are fine textured mixes



of silts and clays.  From Ludlam's (1967) work it appears that 1.2-1.4 m



(4 ft) of sediments have been deposited during the past 100 years.  Littoral


                                186

-------
    I.Or-
               epilimnion: hypolimnion
   O.I
01
                                        epilimnion: me to limn ion
                                          + hypolimnion
  0.01
I
I
I
     141-  155- 169- 183- 197-  211-  225- 239- 253- 267- 281-  295- 309- 323-
     154   168  182  196  210  224  238 252  266  280 294  308 322  336

                          DAYS  OF  YEAR


Figure 2.  Ratios  (by volume) of epilimnion to hypolimnion and of epilimnion to
          metalimnion plus hypolimnion as a function of  season.
                                  187

-------
sediments at the south end of the lake, studied by Vogel (1973), were found
to contain from less than 1% to 5% organic matter.  Up to 3 m (10 ft) of
sediment appear to have accumulated in portions of this area during the past
three-quarters of a century based on comparisons of bathymetric charts
(Maffa, personal communication).
     Seasonal patterns of precipitation are shown in Figure 1.  The heaviest
single storm rainfall of record occurred on July 7-8, 1935 when 20.89 cm
(8.22 in) fell and the second heaviest (17.91 cm or 7.05 in) was associated
with a tropical storm June 21-25, 1972.
     Cayuga Lake is perpendicularly intercepted at its north end by the
Seneca River which is, at the same  time, the major tributary and the sole
surface outlet.  In calculating material budgets the most logical course
would seem to dictate the exclusion of Seneca River inputs since its entrance
to and exit from the lake are so contiguous.  Most of the other larger
tributaries are located at or near the south end (Figure 3).  Fall Creek has
the highest annual flow followed respectively by Cayuga Inlet,  Salmon Creek
and Taughannock Creek (U. S. Department of the Interior, 1971).  There are
no measurements of subsurface flows, but the close agreement of most inflow
and outflow estimates for surface waters indicates that groundwater is not
likely to be a large component of the hydrologic budget.
     Currents have been little studied.  Sundaram et al. (1969) estimated
that in mid to late September, 1968 typical wind induced surface currents
were less than 3 cm (0.1 ft) sec  .  At other times during the  stratified
season, major currents with velocities as great as 50 cm (1.6 ft) sec   were
associated with seiche motions.  They found significant hypolimnetic currents,
shown in an example to be as high as 10 cm  (0.3 ft) sec  , were found only in
associations with seiches.  There are several indications  (Sundaram et al., 1969;
Henson et al., 1961; and Wright, 1969a) of geostrophic effects  but these have not
                                 188

-------
           CAN06A CR.
        SHELDRAKE
                                                                CASCADILLA CR.
                                     10
15
20
25
30
                                                            KILOMETERS
Figure 3.   Location map of Cayuga Lake showing principal  tributaries and sites
           of  sampling stations used in the various  limnological studies.
                                     189

-------
been  systematically  studied.


     Henson et al. (1961), Wright (1969b), Singley (1973), Likens (1974b) and


Oglesby (unpublished) have used differing methodologies and rationales to


compute water renewal times in Cayuga Lake.  Excluding the Seneca River from


the calculations, Oglesby (unpublished) estimates this to have been 8.6 yr


for the 1970-71 hydrologic year.  Wright (1969b) has computed that, depending


upon climatic conditions, the water renewal time may vary between 8.1 and


24.1 yr.  Singley (1973) calculated that for 1965, an exceptionally dry


year with higher than normal evaporation rates, the water renewal time was


about 18 yr.



          LIMNOLOGICAL CHARACTERISTICS - PHYSICAL AND CHEMICAL



     Beginning with winter isothermy, a generalized temperature regime


would show minimum homothermy at a temperature of 1.5-3.3°C sometime between


late February and early April.  Gradual warming but continued homothermy


occur until about mid-May at which time surface temperatures begin to gradually


increase.  Stratification exists by mid-June or early July.  Maximum summer


bottom temperatures are largely a function of mixing in May and early June


and vary from year to year between 4.1 and 5.5°C.  Maximum recorded surface

                                                         \
temperature for a given year ranges from about 20 to 27°C.  Annual maximum


bottom temperatures of 6.6 - 9.6°C are associated with fall homothermy which


occurs between early November and December.  The water column generally


mixes freely until minimum homothermy is reached.  Since 1910, one or more


temperature profiles have been taken during seventeen years.


     Specific conductance during the winter is about 600 |imhos cm  (Wright,


1969c).  As a result of ion dilution by heavy spring runoffs of snowmelt

                                               _ 1
and rain, values decrease to below 500 jumhos cm  • A gradual increase takes


place over the summer, especially in the hypolimnion, with temporary
                                 190

-------
decreases occurring in association with, periods of heavy precipitation
(Dahlberg, 1973).  The higher specific conductances characteristic of the
hypolimnion during the stratified period are thought to be due to deep
groundwater inflow or solubilization of bedrock within the basin proper.
     Data on solar radiation and light extinction coefficients have been
summarized for 1968-70 (Table 1) by Peterson (1971).

Table 1.  Monthly means of solar radiation and extinction coefficients during
          1968-70.  Number of values averaged are shown in parentheses.
                                Solar radiation          Extinction coefficient
     Month                    (gm cal cm~2 day"1)        	(k)	
      Jan                           112 (3)                      0.250 (1)
      Feb                           221 (3)                      0.292 (1)
      Mar                           293 (3)                      0.250 (1)
      Apr                           421 (3)                      0.463 (2)
      May                           450 (3)                      0.301 (4)
      Jun                           511 (3)                      0.370 (3)
      Jul                           529 (3)                      0.854 (4)
      Aug                           472 (3)                      0.598 (10)
      Sep                           358 (3)                      0.403 (4)
      Oct                           234 (3)                      0.321 (2)
      Nov                           103 (3)                      0.286 (3)
      Dec                            93 (3)

     Color was reported (Dahlberg, 1973) to average 6 mg 1 "Xpresumably he
meant color units) in samples taken from various strata at a series of stations
during the summer and early fall of 1972.
     In reviewing the published (Wagner, 1927; Burkholder, 1931; Henson et al.,
1961; Wright, 1969d; and Dahlberg, 1973) and unpublished data on hydrogen ion
concentration in Cayuga Lake, a general pattern emerges of minimum water
column averages (pH 7.7-8.0) during the winter months.  An increase to a pH
of about 8 occurs prior to stratification.  During the summer, hypolimnetic
pH decreases fairly rapidly to a low of 7.7-7.8, with occasional values to
                                191

-------
7.5 prior to autumnal mixing.  At the same time pH in the epilimnion reaches


a maximum (as high as 9.0) averaging 8.2-8.4.   The hydrogen ion concentration


then drops during the mixing period and reaches its winter minimum in


January or February.


     Dissolved oxygen follows a pattern to be expected for a cold, deep,


moderately productive lake.  During the summer, daytime supersaturation is


fairly common in the epilimnion, and hypolimnetic concentrations decrease


seasonally, reaching a minimum of about 6 mg 1  in the deepest portion of the


lake just before fall overturn.  The water column is only 80-90% saturated


at the time of complete autumnal mixing.  Dissolved oxygen increases gradually


during the winter and reaches 90-95% of saturation by the time thermal


stratification is reestablished in the summer.  Hypolimnetic minima do not


appear to have changed since the early part of this century.  Data on the


spatial and temporal distribution of dissolved oxygen have been reported by


Birge and Juday (1914), Wagner (1927), Burkholder (1931), Henson et al.  (1961),


Wright (1969e), and additional, unpublished (Godfrey and Oglesby) records


are available for 1972-74.

                                                                    _3
     Total phosphorus  (TP) typically ranges from about 15 to 22 mg m    through-


out the water column during all seasons of the year (Peterson, 1971; Oglesby


and Schaffner, MS 1975).  During the stratified season, this becomes parti-


tioned in the epilimnion so that soluble reactive phosphorus (SRP) is only


5-15% of the total  (Barlow, 1969) with resultant SRP concentrations being

                              -3                        -3
almost always less  than 5 mg m   and often only 1-2 mg m   and with concomitant


increases in soluble unreactive and particulate phosphorus  (Peterson, 1971).


In the hypolimnion  SRP was nearly always 50% and sometimes as much as 90%


of the total during 1968  (Barlow, 1969).  Over a three year period  (1968-70,


n = 133) of sampling Peterson  (1971) found that TP ranged from 9.1 to 56.7

    -3
mg m   .  Seasonal variations in the forms and  concentrations of phosphorus

                                 192

-------
 (Wright, 1969f; Barlow, unpublished; and Godfrey, unpublished), an elegant


 series of continuous culture bioassays (Peterson et al., 1973) and alkaline


 phosphatase activity (Griffin, 1974) all indicate that phosphorus is the


 critical element in controlling the level of summer phytoplankton production.


     Nitrate nitrogen varies with depth during the summer but the most


 marked fluctuations occur between seasons and, on occasion, between years.


 Concentrations are almost always high enough to be in excess of the minimum


 needed for unrestricted phytoplankton growth (Barlow, 1969) with the mid-


 summer period of 1973 being an exception (Godfrey, unpublished).  Maximum


 input is via tributary inflow during the spring and concentrations are still

                      _3
 typically 800-900 mg m   in mid-May.  Following stratification, nitrate


 decreases erratically in the epilimnion and a slight vertical cline of


 increasing concentration becomes apparent (Federal Water Quality Administra-


 tion, 1965; Wright, 1969f; Dahlberg, 1973; Godfrey, unpublished).  Data on


 ammonium nitrogen are scarce but concentrations appear to be generally low,


 ca. 0-40 mg m~3 (Dahlberg, 1973).  In the summer of 1972, Kjeldahl nitrogen

                              _3
 ranged from about 200-500 mg m   (Dahlberg, 1973) with hypolimnetic concen-


 trations being lower than those of the surface water but with maxima some-


 times occurring in the metalimnion.


     Total alkalinities of Cayuga Lake water are on the order of 100 mg 1


 as CaC03 (Wagner, 1927; Burkholder, 1931; Henson et al., 1961; Wright, 1969d;


 Dahlberg, 1973; and Godfrey, unpublished).  Winter values are generally higher


 than this and an annual minimum occurs in July - September.  The variation


within a year is 10-15 mg 1   as CaCCL.  During the stratified season there


 is a slight increase in alkalinity with depth.  The only published values of


 acidity are those of Dahlberg (1973) for 1972.  Mean, minimum and maximum


 concentrations were, respectively, 2.6, 0 and 9.3 mg 1  .  Increases during


 the stratified season were noted for metalimnetic and hypolimnetic samples.

                                 193

-------
     Cayuga Lake has a well developed calcium carbonate buffer system, and

concentrations of sodium and chloride are unusually high for an inland lake

in the northeastern United States (Federal Water Quality Administration,

1965; Berg, 1966; Dahlberg, 1973; and Oglesby, unpublished) as shown in

Table 2.
Table 2.  Major anions and cations in Cayuga Lake during April, 1973 as
          determined from samples composited for depth.
               Cations
                                           Anions
MEQ
Ca^
1 i
,, ++
Mg
Na+

K+
TOTAL
2
0
1

0
4
.20
.86
.85

.07
.98
mg
44.
10.
42.

2.

i
0
5
5

8

MEQ
C0=
HC03
so7
4
Cl~
TOTAL
0
2
0

2
5
.07
.00
.76

.34
.17
mg I"1
2
122
37

83

.0

.0

.2

     Data on inorganic trace elements are summarized in Table 3.
Table 3,
Element

  Fe
  Mn
  Bo
  Zn
  Cu
  Pb
  Cd
  Co
  Al
  Mg
1]
1]
1]
1]
1]
1]
      Inorganic trace elements in Cayuga Lake based on data obtained in
      the summers of 1971 and 1973.  With the exception of those for boron,
      "observations" represent averages for samples taken from two or
      three depths corresponding to the major thermal strata at from one
      to five sampling stations.

                   Typical
        Range   concentration
       (mg m~3)   (mg m~3)     observations              References
3-220
1-30
22-55
0.51-9.41
0.10-0.93
0.10-0.93
0.015-1.98
0.003-0.093
0-20
0.6-14
-
_
34
2.7
0.6
0.12
0.54
0.005
-
-
 Number  of
observations

     11

      4
     21
      4
      4
      4
      4
      4
      2
      5
Dahlberg Q-973), Oglesby (unpub-
  lished)
Oglesby (unpublished)
   ii          it
Mills and Oglesby (1971)
                                             Dahlberg (1973)
  Insoluble form, euphotic zone
                                 194

-------
                 LIMNOLOGICAL CHARACTERISTICS - BIOLOGICAL





     Data on pigment concentrations in Cayuga Lake have been reported by



Hamilton (1969), Wright (1969g), Barlow (1969), Peterson (1971), Dahlberg



(1973) and Oglesby and Schaffner (1975) and detailed information for 1972-73



has been collected by Godfrey (unpublished).   An annual maximum is generally



found in late June or July and a secondary peak often occurs in the autumn.



Peterson's (1971) chlorophyll a_ concentrations for June, July and August


                            _3
of 1968-70 averaged 4.8 mg m   in the euphotic zone.  For the same period



in 1972-74, epilimnetic mean chlorophyll ji plus phaeophytin ranged from 7.8



to 9.7 mg m~  (Oglesby and Schaffner, MS 1975).


                                            14
     Primary productivity, as determined by   C uptake, values have been



reported for 1957-58 (Howard, 1963) and 1968-70 (Barlow, 1969 and Peterson,



1971).  The variation between years is considerable, but for the latter


                                     -2    -1
period production is about 160 mg C m   day   averaged on an annual basis.



     Bioassays to determine nutrients critical to the growth of Cayuga Lake



phytoplankton are among the best designed and most comprehensive of any so



far done for freshwater systems.  Using continuous cultures of naturally



occurring phytoplankton communities in lake water, the role of phosphorus



in limiting growth during mid and late summer of 1971 and 1972 has been con-



vincingly demonstrated (Barlow et al., 1973 and Peterson et al., 1973).



     The phytoplankton of Cayuga Lake is comprised of a mixture of associations



some of which have been described in the literature as being indicative of



oligotrophy and others as typifying eutrophic conditions.  Myxophycean "blooms"



occur at times during the summer but are not persistent.  Seasonal patterns



of succession and peaks of abundance as indicated by cell counts, species



biomass, and pigment concentration are highly variable from year to year.



A general pattern of maximum standing crop from late June into early October



exhibits large week to week fluctuations with surface chlorophyll £ ranging



                                 195

-------
                         -3                -3
from a low of near 1 mg m   to over 20 mg m   on one occasion in 1972.



Both cell counts and species composition indicate a probable trend to more



eutrophic conditions when data from 1910-1930 are compared with those for



1950-74.  Barlow (1969), Dahlberg (1973), and Godfrey (unpublished) have



compiled comprehensive descriptions of the phytoplankton communities species



composition in recent years.



     The zooplankton (Birge and Juday, 1914; Birge and Juday, 1921; Muenscher,



1927; Bradshaw, 1964; Hennick, 1973; and Behrman, unpublished) and benthic



fauna (Birge and Juday, 1921; Henson, 1954; Green, 1965; and Dahlberg, 1973)



are typical of deep, moderately productive north temperate latitude lakes.



There is no evidence of qualitative changes in either over the last sixty



years, but limited data indicate that summer standing crops of zooplankton



may have increased.  Cyclops bicuspidatus is the dominant copepod and



Bosmina longirostris the most abundant of the Cladocera in the summer zoo-



plankton.  Abundant Mysis relicta are an important food resource for some



species of fish.



     The fish population i.s managed to maximize salmonid production (Youngs



and Oglesby, 1972),  Significant sport fisheries also exist for smelt, small-



mouth bass and other species.  The principal food chain associated with the



limnetic zone is: phytoplankton and detritis	^zooplankton	>alewives •—



—» salmonids.



     The bacterial flora is virtually undefined.  A limited amount of data



are provided by Dahlberg (1973).  The benthic flora, exclusive of rooted



plants, is unstudied.  Cladophora sp. is abundant is the littoral zone in



some locations and fishermen report that growths of this attached alga have



increased in recent years.




                                19.6

-------
     Dense growths of rooted macrophytes occur in a limited area of shallow
water at the southern end of the lake and over a much larger area at the
northern end.  Historical data on plant growths at the head end of the lake
indicate a possible increase in plant density and a shift to species,
especially millfoil, that constitute more of a nuisance (Vogel, 1973; Oglesby,
Vogel? Peverly and Johnson, MS 1974).

                                NUTRIENT BUDGETS

     Budgets and loadings for three different kinds of phosphorus are given
in Table 4.  Inputs of total phosphorus and molybdate reactive phosphorus

Table 4.  Phosphorus inputs and loadings (excluding the Seneca River) for
          total and molybdate reactive phosphorus (1970-71) and for "bio-
          logically available" phosphorus (1972).
                     Total P             MRP         "Biologically available" P
Source	  (kg x 1Q~3 yr"1)   (kg x 10~3 yr"1)       (kg x 10~3 yr~l)
Waste discharges
Land runoff
Precipitation
Ground water
Other
Total
Volumetric loading
(mg m~3 yr-1)         14.9               10.0                   12.6
Areal loading
g nr2 yr-1             0.81               0.54                   0.69

(unfiltered) are based on a one year study by Likens (1972, 1974a and b) in
which the contributions of P in precipitation and in 25 tributaries (draining
almost 78% of the lake basin watershed) were monitored.  "Waste discharge"
and "Land runoff" categories were subsequently determined by calculating the
former based on estimates of per capita discharge of phosphorus to the
tributaries and adding to this the P in wastes discharged directly to the
                                197
88.6
47.4
3.4

139.4
88.6
2.0
3.4
94.0
88.6
26.1
3.4
118.1

-------
lake (Oglesby and Schaffner, 1975 and Oglesby and Schaffner, MS 1975).
Phosphorus from land runoff was then determined by difference.  The budget
for "biologically available" P contains a "Land runoff" estimate based on
the use of export coefficients, determined during an intensive 18 month
study of the Fall Creek watershed (Bouldin, unpublished), for the sum of
SRP, dissolved unreactive P and the fraction of P associated with suspended
particulates that desorbs in aqueous solution.  The runoff (export)
                  -2   -1
coefficients (mg m   yr  ) for land in various use categories were: 13.2
for agriculture, 8.3 for forest and 100 for residential usage.
     A budget for soluble nitrogen exclusive of organic N, is given in
Table 5.  The essential components are derived from Likens' (1972, 1974a and b)

Table 5.  Soluble nitrogen inputs and loadings (excluding the Seneca River)
          for 1970-71.
                                      Soluble N
Source	          (kg x 1Q~3 yr~l)
Waste discharges                        200.3
Land runoff                           1,694.1
Precipitation                           565.6
Ground water                              ?
Other                                     ?
Total                                 2,460.0
                        -3   -1
Volumetric loading (mg m   yr  )        262
                  -2   -1
Areal loading (g m   yr  )               14.2

1970-71 study of tributary and precipitation inputs.  As was the case for
phosphorus, the "Waste discharge" category was calculated and "Land runoff"
obtained by difference for the tributary input.  In the calculation of the
former a per capita discharge of 4.44 kg yr   (01sson,Karlgren and Tullander,
1968) and a treatment efficiency (all types of disposal systems) for N removal
of 50% were assumed.
     Other macronutrient budget information calculated by Likens is summarized
in Table 6.
                                198

-------
Table 6.  Sulfur, silicon, calcium, magnesium and bicarbonate inputs and
          loadings from precipitation and tributary inflow (excluding the
          Seneca River) during 1970-71.

                    Input           Volumetric loading    Areal loading
Nutrient       (kg x 10~3 yr~l)       (mg m~3 yr"1)       (gm m~2 yr"1)
S04= - s
Si02 - Si
Ca^
M ++
Mg
HCO~ - C
13,253
2,147
63,802
15,263
31,523
1,410
229
6,800
1,630
3,360
76.6
12.4
369
88.2
182
                               DISCUSSION


     As a moderately large and deep, cold water lake affected by a variety

of human influences, Cayuga is representative of many important bodies of

water formed in north temperate latitudes by the action of glaciers.  Its

relatively uncomplicated morphology (low shoreline development, restricted

littoral zone except at the tail end, and single basin) make Cayuga an

excellent site for elucidating limnological principles.  The existence of a

substantial body of knowledge, accumulated over the past century, places it

among the limnologically better defined lakes in the world.

     For the present emphasis on examining primary production in an ecological

context, adequate data are available on the more static properties, e.g.,

geology and morphometry, and, for one or more years, on many of the more

changeable parameters such as the distribution and loading of primary nutrients,

algal standing crops and transparency.  Data on primary production rates,

grazing, and benthic productivity are more limited.

     Based on most biotic and associated abiotic descriptive properties,

Cayuga Lake falls in the mesotrophic category; yet, for given parameters and

at specific times, it could be termed either eutrophic or oligotrophic.

                                199

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The composition of the phytoplankton is especially illustrative of an inter-
mediate trophic status since dominant groupings commonly cited as being
typical of both oligotrophic (e.g., Cyclotella, Tabellaria, chrysomonads and
Sphaerocystis) and eutrophic (e.g., Myxophyceae and Melosira) conditions
                                                                           _3
occur.  Mean summer euphotic zone chlorophyll concentrations (ca. 5-10 mg m  ),
                                                             -2    -1
primary production rates (annually on the order of 160 mg C m   day  ), hypo-
limnetic dissolved oxygen (minimum concentration of about 6 mg 1  ), the
composition of the fauna (the fishes include both salmonids and carp, Mysis
relicta), and the standing crop of profundal benthos (0.5-1.0 gm organic
        _2
matter m  ) reinforce the picture of mesotrophy.  There is evidence that pro-
ductivity has increased when data from the 1910-1930 period are compared with
those from 1950-1974.
     When data on Cayuga Lake are fitted to the graphics of trophic state as
a function of total P loading vs. mean depth (Vollenweider, 1968) or vs. the
ratio of mean depth tr water residence time (Vollenweider as given by Dillon,
MS 1974), a eutrophic condition (about the same as Malaren) is indicated
with total P loadings above the so-called "dangerous" level.  The reasons for
this lack of fit to the Vollenweider plots can only be speculated on at
present.  Several possible factors are: (1) 15% of the total phosphorus loading,
namely that adsorbed to soil particles, is estimated to remain unavailable
for biological uptake, (2) Cayuga's simplified morphology and aerobic hypolimnion
probably minimize the internal recycling of phosphorus compared with that
which occurs in some lakes, (3) there could be significant errors in the
calculation of specific phosphorus loading, and (4) the parameters used in
the Vollenweider plots are invalid, or at least inaccurate, in defining trophic
state.
     Ignoring mean depth and water retention time, Oglesby and Schaffner
(MS 1975) have obtained the following relation between summer chlorophyll
                                  200

-------
 (mean for the epilimnion) and the specific loading of "biologically available"

 phosphorus for New York's Finger Lakes.

          Y = 21.8X - 1.57           (r = 0.62, n = 21)

 They postulate that depth becomes an important factor only when it is

 necessary to separate lakes that essentially mix to the bottom throughout

 most of all of the year from those that exhibit summer stratification.


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  New York.  Everts and Ensign, Philadelphia.  687 p.

 Barlow, J. P.  1969.  Chapt. XVI.  The phytoplankton.  In R. T. Oglesby and
  D. J. Allee, eds.  Ecology of Cayuga Lake and the proposed Bell Station
  (nuclear powered).  Cornell Univ. Water Resources and Mar. Sci. Center
  (Ithaca, N.Y.).  Publ. No. 27.  466 p. + appendix.

 Barlow, J. P., W. R. Schaffner, F. deNoyelles, Jr. and B. J. Peterson.  1973.
  Continuous flow nutrient bioassays with natural phytoplankton populations.
  JLn_ G. E. Glass, ed.  Bioassay techniques and environmental chemistry.
  Ann Arbor Sci. Publishers.  499 p.

 Berg, C. 0.  1966.  Middle Atlantic States.  In D. G. Frey, ed.  Limnology
  in North America.  University of Wisconsin Press, Madison.  734 p.

 Birge, E. A. and C. Juday.  1914.  A limnological study of the Finger Lakes
  of New York.  Doc. No. 791 from Bull. Bur. Fisheries (1912) 32:525-609.

	.  1921.  Further limnological observations on the
  Finger Lakes of New York.  Doc. No. 905 from Bull. Bur. Fisheries (1919-20)
  37:210-252.

 Bradshaw, A. S.   1964.  The crustacean zooplankton picture: Lake Erie 1939-49-59;
  Cayuga 1910-51-61.  Verh. Internat. Verein. Limnol.  15:700-708.

 Burkholder, P. R.  1931.  Studies in the phytoplankton of the Cayuga basin,
  New York.  Bull. Buffalo Soc. Nat. Sciences 15(2):21-181.

 Child, D., R. T. Oglesby and L. S. Raymond, Jr.  1971.  Land use data for the
  Finger Lakes region of New York State.  Cornell Univ. Water Resources and
  Mar. Sci. Center (Ithaca, N.Y.).  Publ. No. 33.  29 p.

 Cline, M. G. and R. W. Arnold.   1970.  Working draft soil association maps
  for New York.   Unpublished.

 Dahlberg, M.  1973.  An ecological study of Cayuga Lake,  New York.  Vol. 4.
  Report to New York State Electric and Gas Corporation.   NUS Corp.
  (Pittsburgh, Pa.).  171 p. + appendices.


                                   201

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Dethier, B. E. and A. B. Pack.  1963.  Climatological summary, RURBAN Climate
  Series No. 1, Ithaca, New York.  N.Y. State College of Agriculture (Ithaca,
  N.Y.).  12 p.

Dillon, P. J.  MS 1974.  Progress report on the application of the phosphorus
  loading concept to eutrophication research.  A report prepared on behalf of
  R. A. Vollenweider for NRG Associate Committee on Scientific Criteria for
  Environmental Quality Subcommittee on Water, Canada Centre for Inland Waters,
  Burlington, Ont.  28 p.

Dudley, W. R.  1886.  The Cayuga flora.  Bull. Cornell Univ. (Ithaca, N.Y.).
  Vol. II.  132 p.

Federal Water Pollution Control Administration.  1965.  Unpublished notes.

Green, R. H.  1965.  The population ecology of the glacial relict amphipod
  ?OYltopotL
-------
Ludlam, S. T.  1967.  Sedimentation in Cayuga Lake, New York.  Limnol. Oceanogr.
  12(4):618-632.
Mills, E. L. and R. T. Oglesby.  1971.  Five trace elements and vitamin
  in Cayuga Lake, New York.  Proc. 14th Conf .  Great Lakes Res.  p. 256-267.

Muenscher, W. C.  1927.  Plankton studies of Cayuga, Seneca and Oneida Lakes.
  In A biological survey of the Oswego River system.  Suppl. 17th Ann. Rpt.
  N.Y. State Conservation Dept.  J. B. Lyon, Albany.

Oglesby, R. T. and W. R. Schaffner,  1975.  Nitrogen, phosphorus and eutro-
  phication in the Finger Lakes.  Cornell Univ. Water Resources Mar. Sci.
  Center (Ithaca, N.Y.).  Tech. Rpt. No. 94.  27 p .

Oglesby, R. T. and W. R. Schaffner.  MS 1975.   The response of lakes to
  phosphorus .

Oglesby, R. T. , A. Vogel, J. H. Peverly and R. Johnson.  MS 1974.  Changes
  in submerged plants at the south end of Cayuga Lake following Tropical Storm
  Agnes .

Olsson, E. , L. Karlgren and V. Tullander.  1968.  Household waste water.
  Byggforskningens Rapport 24.  Natl. Swedish Inst. Bldg. Ros., Stockholm.
  162 p.

Peterson, B. J.  1971.  The role of zooplankton in the phosphorus cycle of
  Cayuga Lake.  Ph.D. thesis.  Cornell Univ. (Ithaca, N.Y.).  131 p.

Peterson, B. J., J. P. Barlow and A. E. Savage.  1973.  Experimental studies
  on phytoplankton succession in Cayuga Lake.   Cornell Univ. Water Resources
  Mar. Sci. Center (Ithaca, N.Y.).  Tech. Rpt. 71.  23 p.

Raffieux, P.  1671-72.  The Jesuit relations and allied documents 56:48-52.

Rickard, L. V. and D. W. Fisher.  1970.  Geologic map of New York.  Finger
  Lakes Sheet.  New York State Museum and Sciences Service (Albany, N.Y.).

Singley, G. W.  1973.  Distribution of heat and temperature in Cayuga Lake.
  Rpt. prepared for New York State Electric and Gas Corporation by NUS Corp.
  (Rockville, Md) .  p. 1-91 + appendices.

Sundaram, T. R. , C. C. Easterbrook, K. R. Piech and G. Rudinger.  1969.  An
  investigation of the physical effects of thermal discharges into Cayuga Lake
  (analytical study).  Cornell Aeronautical Lab., Inc.  (Buffalo, N.Y.).  CAL
  No. VT-2616-0-2.  306 p.

Thompson, D. Q.  1972.  Trees in history.  The Cornell Plantations 28(3):39-42.

United States Bureau of the Census.  1970a.  Census of population.  General
  population characteristics.  Final Report PC(1) - B 34, New York.  U. S.
  Govt. Print. Off., Washington, D. C.

                                     1970b.  Census of housing.  Block
  statistics for selected areas of New York State.  Final Report HC(3) - 163.
  U. S. Govt. Print. Off., Washington, D. C.

                                 203

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United States Dept. of Interior.  1971.  Water resources data for New York.
  Part I.  Surface water records.  U. S. Geol. Surv. (Albany, N.Y.).  311 p.

Vogel, A.  1973.  Changes in the submerged aquatic flora at the south end of
  Cayuga Lake between 1929 and 1970.  M. S. thesis.  Cornell Univ.  (Ithaca, N.Y.)
  71 p. + appendix.

Vollenweider, R. A.  1968.  The scientific basis of lake and stream eutro-
  phication, with particular reference to phosphorus and nitrogen as eutro-
  phication factors.  Tech.  Rpt. OECD, Paris,  DAS/CSI/68, 27:1-182.

Wagner, F. E.  1927.  Chapt. V.  Chemical investigations of the Oswego water-
  shed.  In A biological survey of the Oswego  River system.  Suppl.  17th Ann.
  Rpt., N. Y. State Conservation Dept.  248 p.

Whitford, N. E.  1906.  History of the canal system of the State of New York.
  Vol. 1.  Suppl. Ann. Rpt.  State Eng. Surv. N. Y. State.  1025 p.

Wright, T. D.  1969a.  Chapt. VII.  Currents and internal waves,  _In R. T.
  Oglesby and D. J. Allee, eds.  Ecology of Cayuga Lake and the proposed Bell
  Station (nuclear powered).  Cornell Univ. Water Resources Mar. Sci. Center
  (Ithaca, N.Y.).  Publ. No. 27.  466 p. + appendix.

	.  1969b.  Chapt. V.  Hydrology and flushing characteristics.
  op. cit.

  	.  1969c.  Chapt. VIII.  Conductivity,  op. cit.

  	.  1969d.  Chapt. XIV.  Alkalinity and pH.  op. cit.
               1969e.  Chapt. X.  Chemical limnology and Chapt. XI.  Hypolimnetic
  oxygen,  op. cit.

  	.  1969f.  Chapt. XIII.  Plant nutrients,  op. cit.

  	.  1969g.  Chapt. XV.  Plant pigments (chlorophyll a_ and phaeophytin)
  op. cit.

Youngs, W. D.  1969.  Chapt. XVIII.  Fish and other biota.  In R. T. Oglesby
  and D. J. Allee, eds.  Ecology of Cayuga Lake and the proposed Bell Station
  (nuclear powered).  Cornell Univ. Water Resources Mar. Sci. Center (Ithaca,
  N.Y.).  Publ. 27.  466 p. + appendix.

Youngs, W. D. and R. T. Oglesby.  1972.  Cayuga Lake: effects of exploitations
  and introductions on the salmonid community.  J. Fish. Res. Canada  29:787-794.
                                204

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          TROPHIC STATUS AND NUTRIENT BALANCE FOR CANADARAGO LAKE


                 Dr. Leo J. Metling and Dr. Thomas E. Harr

                     Environmental Quality Research Unit
           New York State Department of Environmental Conservation
                              Albany, New York

                                     and

                   Dr. G. Wolfgang Fuhs and Susan P. Allen

                         Environmental Health Center
                    Division of Laboratories and Research
                     New York State Department of Health
                              Albany, New York


                                INTRODUCTION
     Canadarago Lake, located in Otsego County, east-central New York State
has been the scene of an intensive investigation by the New York State Depart-
ments of Environmental Conservation and Health.

     Canadarago Lake is a stratified lake of moderate size (759 ha).   From its
morphometry (7m mean depth),  it can be expected to be moderately eutrophic but
at the beginning of the New York State study, appeared strongly eutrophic with
dense blue-green algae blooms, a condition which appeared to be caused by the
input of sewage from the village of Richfield Springs and from summer camps.
When the study began in 1968, Richfield Springs was under State Health Depart-
ment orders to stop discharging raw sewage into the lake.

     The advanced state of eutrophication in this lake called for the construc-
tion of a modern sewage treatment plant which included some form of nutrient
removal.  The concern of the  local residents, the proximity of the lake to
Albany, and the fact that Canadarago Lake typically represents the condition
of a number of lakes within the state, made it a logical candidate for a pilot
demonstration study.

     The only prior published data concerning an investigation of Canadarago
Lake occurred as the result of the biological survey of the Delaware and
Susquehanna watersheds performed by the New York State Conservation Department
during the summer of 1935 (1).  Even at this early data Canadarago Lake showed
evidence of eutrophication.  Throughout the text comparisons of the present
study with that of 1935 are presented.
                                     205

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              BRIEF GEOGRAPHIC DESCRIPTION OF WATER BODY
A-D.  GEOGRAPHICAL DATA

      Canadarago Lake  is  situated  in  east-central New York State, Figure 1,
at an elevation of 390m (1280  ft)  above  mean sea level.  Canadarago Lake
together with its 175  km^ of drainage area,  Figure 2, forms the northeastern
headwaters of the Susquehanna  River watershed,  originating in Herk-imer an^
Otsego counties.  The  drainage basin  for this lake is bounded between
74° 53' 33" West Longitude  and 42° 46'  18"  North Latitude with the centroid
of the lake located at 75°  00'  25" West  Longitude and 42° 49' 00" North
Latitude.  The surrounding  terrain is hilly, with ground elevations ranging
from 396m (1300 ft) to 579m (1900  ft) above mean sea level.

      Four major tributaries,  Figure  3,  drain 78.3 percent of the watershed:
Ocquionis Creek which  discharges at the  north end of the lake, and Mink
Creek, Hyder Creek and Herkimer Creek which discharge along its western
shore.  The eastern portion of the watershed is too narrow and steep to
support permanent streams.  The lake  is  drained at its southern end by
Oaks Creek, which flows south  to join the Susquehanna River at Index, New
York.
                FIGURE I.
        LOCATION OF CANAOARAGO LAKE
           IN NEW YORK STATE
      FIGURE Z.
CANADARAGO LAKE WATERSHED
                                   206

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                                                   OCQUIONIS CR
                   N
         N.YS. BOAT LAUNCHING
                                                FIGURE  3.
                                          CANADARAGO LAKE AND
                                              ITS TRIBUTARIES
E.
GENERAL GEOLOGICAL CHARACTERISTICS
      The bedrock geology and Pleistocene glacial modifications  are  strongly
reflected by the present physiography of the Canadarago Lake drainage  basin.
The bedrock of the drainage basin is predominantly Onondaga and  Helderberg
limestone in the north and the Hamilton shales and siltstones  in the south.
The contact between these two formations is the boundary between two dis-
tinct physiographic units.

      This area of New York State was glaciated several times  during the
Pleistocene epoch, but evidence is preserved only for the  latter stages
of the Wisconsin Glacial period.  Two major glacial lobes  thrust over  the
drainage area during this Glacial period, approximately 11,000-12,000  years
ago.  One advance was in the north-south direction and was probably  respon-
sible for the outwash deposits found to the south of the drainage basin.
This advance may have been responsible for forming the oversteepened north
faces of the shale siltstone ridges which predominate in the southern  half
of the drainage basin.  The second advance was in the west-southwesterly
                                    207

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direction.   This  advance is marked by  several endmorainic deposits in the
northern section  of the drainage basin.   Also,  the lack of high-lime
glacial drift  on  the southern portions of the drainage basin  indicates
little movement of limestone in the north to south direction.   Flint (2)
estimated the  thickness of the ice sheet  at the time of its maximum advance
to have been 1000 to 1200m (3281 to 3937  ft).  The glacial and  subsequent
periglacial  periods strongly influenced the character of  soils  found in
the drainage basin.   Ocquionis and Mink Creeks  originate  in Herkimer County
and drain from the gently undulating east-west  oriented limestone  unit.
The stream forms  a typical trellis drainage pattern.  The valley floors
contain many swamps and muck deposits.  Local relief between  valley floors
and ridge tops is generally less than  30m (98.5 ft).  Hyder and Herkimer
Creeks, in contrast, originating in Otsego County, are in the shale upland
unit.  Physiographically, this area is characterized by a strong local
relief and dendritic drainage patterns.   The local relief is  as much as
200m (656 ft)  from valley floors to surrounding ridges in some  places.
The streambeds are on gravel or bedrock.   There are no muck deposits within
the major stream  system.

F.  VEGETATION

    On the slopes and hills of the Canadarago Lake watershed  are woods of
mixed deciduous  trees, primarily maple and oak.  A narrow band  of  trees
surround the lake anrf an agricultural  belt is located between them.  A
swampy woodland  is located at the southern end of the lake.

G.  POPULATION

    The village  of Richfield Springs  is  the only significant, permanent
population concentration in the watershed.  In 1970, the  population of the
village was  1527  (3) and records indicate that the population has  been
nearly constant  for 20 years (4, 5).   During the summer months, approxi-
mately 1300  additional people occupy  summer cottages around  the lake shore.
The total permanent resident population  of the entire watershed is not
known but  it is  estimated to be on  the order of 3500 people.

H.  LAND  USAGE

    About  49 percent of  the watershed  is devoted to agriculture, mostly
dairy farms, and approximately 34 percent is in forest or brushland (6,7,8),
Table 1  is  a summary of  the land use  within the watershed.   Using the

                             Table 1.  LAND USE IN THE LANADARAGO LAKE MTERSHEb
                                            Area   >   Watershed Area
                                           (k.2)   !    (Percentage)
                        Agriculture and Agriculture      86.93         49.00
                          Facilities
                        Forett

                        Mater Resources

                        Wetlands

                        Residential

                        Conerclal

                        Industrial

                        Mining
60.10   |     34.02

12.38   j.      7.01

11.49         6.SI

 3.88         2.26
 0.66
            .38
 0.07   j      .04

 0.35   '      .20
                        Public, Semlpubllc and
                          Transportation       I    0.46    ;      .26

                        Outdoor Recreation       ,    0.56          .32
                        Total
                                           176.61    .     100.00
                                       208

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  1964 agricultural  census,  (9,  10),  it has been  estimated  that  there  are
  approximately 6000 cattle, 40  hogs, 50  sheep  and 5000  chickens in  the
  watershed.   A more extensive study  of soil  type and  land  use has been  con-
  ducted by the Department of Agronomy at Cornell University,  Ithaca,  New  York
  which adds  support to these data  (ll).

  I,  WATER USAGE

     The lake is used primarily for  recreational purposes, offering
 recreationat opportunities for the urban residents  of Albany,  100 km
  (60 .miles) to the east,  and Utica, 40 km (25 miles) to the
  northwest.   The recreational potential  of Canadarago Lake has  long been
  recognized  and utilized.   Around  the turn of  the century, this lake  and  its
  larger sister lake, Otsego Lake,  were sites of  summer  homes  and health spas
  for the wealthy.   Although the economic strata  of  the  users  have changed,
  the recreationists  today are the  source of  a  substantial portion of  the
  area's economy.


     A study of the  economic contribution of the recreational aspects of
Canadarago Lake by  the Soil Conservation Service of the United  States De-
partment of  Agriculture  (12) revealed that more  than $663,000 annual  sales
were directly related to the lake  and its existing  recreational  facilities.
In addition,  the lake oriented  properties contribute about $90,000  annually
in local real estate and school  taxes.   This study  further concluded  that
the  lake and its recreational assets are  a significant  contributor  to the
local community and  that, if the Richfield Springs area  was deprived of  the
lake, the area could undergo the economic decline being experienced by  many
other rural  communities  in New York  State.

J.   SEWAGE  AND EFFLUENT DISCHARGE

     The village of Richfield Springs has been served by a combined sewer
system which discharged through  a primary wastewater treatment  plant, to
Ocquionis Creek, at  a point approximately 0.8 km (0.5 mile) upstream  of
its mouth.   The plant had not been operational for  several years since  it
needed significant repairs.  The cottages and residences located around
the perimeter of the lake are served by  septic tanks.   In 1969,  a New York
State Health  Department survey revealed  that 24.4 percent of the septic
tanks had some type of direct discharge  into the lake, by-passing the
leaching fields (13).

     During  1972 the village of Richfield Springs constructed a  modern
wastewater treatment facility to replace the former sewage treatment plant.
The effluent  from the new facility is discharged to Ocquionis Creek  at the
same point as from the previous  facility.  Construction of the  facility
was completed in the summer of 1973.   In November 1972,  the plant began
operation as a secondary treatment plant.  In January 1973, the  tertiary
system for removal of phosphorus was completed.

     This facility, operating as a tertiary treatment plant,  is  capable
of treating 0.37 x 10°  gal • day'1(1.4 x 103m3  • day'1).   The lagoon system,
which provides secondary  treatment, can handle up to 2.5 x 10  gal   • day"-'-
(9.5 x 103m3  • day"1).   Flow in excess of 0.37 x 10° gal • day"1(l.4 x 103
m3 •  day"-1-) is given only secondary treatment and disinfection at the plant.

                                   209

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Wastewater processed through tertiary treatment  will provide 93-94% BOD
removal and up to 90% phosphorus removal, or to a maximum effluent concen-
tration of 0.5 mg P •  liter  .

     In addition to the wastewater treatment plant discharge,  natural
mineral springs effluents enter the lake through the Richfield Springs
wastewater treatment plant and  Ocquionis Creek, introducing quantities of
sulfate, sulfide, magnesium and calcium as pollutants.   Another source of
pollution is a stockpile of road salt located near Mink Creek  which in-
troduces additional chlorides to the lake.
    BRIEF DESCRIPTION OF MORPHOMETRIC AND HYDROLOGIC CHARACTERISTICS
 A.   LAKE LOCATION AND DESCRIPTION

     Canadarago Lake is nearly 6.4 km (4 mi) long,  running north-south
 but is only 1.9 km (1.2 mi) wide at its maximum width.   The shore length
 of- the lake is 14.4 km (9 mi) and 80 percent of the area around the lake
 is  densely populated with summer homes, trailer parks and year-round
 residences.  During the summer months,  seasonal transient occupancy of
 these facilities increases the population of the area by approximately
 1300 people.

     An island, Deowongo Island, is located nearly midway between the
 northern and  southern extremes of the lake and approximately 400 m (1300 ft)
 west of the eastern shoreline.  The island possesses an area of approxi-
 mately 3 ha (7.5 acres) and has a shoreline of approximately 0.8 km (0.5 mi).
 In  addition,  a shoal, submerged in 1 to 2 m (3.3 to 6.6 ft) of water, is
 located approximately 0.4 km (0.25 mi)  from the western shore and 1.5 km
 (0.93 mi) south of the northern extreme of the lake.  Nearly 10 ha (24 acres)
 of  this shoal is submerged in 3 m (10 ft) or less, of water.  Normally,  in
 the summer, it is heavily covered with weed beds.

 B.   VOLUME

     The volume of the lake has been calculated as 57.5 x 106 m3 (2.03 x 109 ft3)
 (14).

     Until 1956 the lake was alloweH to seek its own natural level.  This
 frequently resulted in the lake becoming so low that large areas of the
 lake bottom around the perimeter of the lake became exposed.  This condition
 reduced the lake's attractiveness for recreational and sporting use, de-
 creased the asthetic quality of the area and frequently caused obnoxious
 disagreeable  odors.  To correct this situation, the Canadarago Lake Property
 Owners Association, in 1955, obtained permission from New York State to
 erect a regulatory barrier in Oaks Creek, the outlet from the lake.  This
 barrier could be raised or lowered, as required, in order to maintain the
 lake at a convenient level.  The barrier was constructed and put into
 operation in  1956 and still is controlled by the Property Owners Association.


                                    210

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C-D.  DEPTH

      The maximum water depth in Canadarago Lake is 12.8 m (42 ft) and the
average depth is 7.7 m (25.3 ft).  The lake area is 759 ha (2050 acres).
The lake can be divided into two shallow areas, less than 5 m (16.4 ft) deep
in its northern and southernmost parts.  The remainder of the lake is be-
tween 5 and 10 m (16.4 and 32.8 ft) deep.  The deepest points occur in a
trench just north of the center of the lake and in a spot south of the center
of the lake.
E-F.  STRATIFICATION

      Extensive mixing by the wind of this well-exposed lake produces a
thermocline that is not very sharp and, during most of the season, is
found at a depth of 6 to 8 m (19.7 to 26.3 ft) while secondary thermo-
clines move in from the surface.  The mean depth of the epilimnion during
the summer stratification is 6.7 m (21 ft).  The epilimnion encloses
approximately 72 percent of the lake volume and is maintained from June
through September.

G.  NATURE OF LAKE SEDIMENTS

      The appearance of the sediments of Canadarago Lake is that of a silty
black mud.  Some sand which contains snail shells can be found along shore-
line^areas.

      In August 1973, a sediment core was taken from Canadarago Lake by
driving through 30 cm (12 in.) of sediment with a Kojak Brinkhurst (KB).corer.
The core was extruded, fractionated in the field into 7.5 cm (3 in.)
intervals, placed in polyethylene bags, frozen, and stored at -20°C (-4°F)
until analysis.  Chemical analysis of the core showed the macrocomponents
of the sediment to be in a range typical of hardwater lakes:  silica
270 mg • g~^, calcium 100 mg • g  , aluminum 50 mg • g~ , magnesium 0.6 mg *
(expressed on a dry weight basis).  Organic carbon and total phosphorus con-
tents of the sediments, commonly regarded as indicators of the lake's trophic
level, were found to be 50 mg • g~l and 5 mg • g~* respectively, suggesting
moderate eutrophication.  From previous surveys it was known that the sedi-
ments in the northern, unstratified portion of the lake, off Ocquionis Creek
which has carried raw sewage, were softer and higher in organic matter than
the sediments in the main basin and particularly in its southern part.

H.  PRECIPITATION

      The area has a humid climate with cold winters and mild summers. The
watershed is subject to occasional local cloudburst type of storms.  A
deficiency of rainfall frequently occurs extending through the upper few
inches of soil during part of the summer.

      The total annual precipitation for the Canadarago Drainage Basin over
the 1951-1960 period was 1005 mm (39.3 in.) which includes an average annual
snowfall of 2.5 m (8.2 ft).   The mean temperature for this location, over
the same period of time was 6.9°C (44.4°F) with varying extremes of 37°C
(98°F) down to -36°C (-32.8°F) (15).

                                   211

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I.  INFLOW AND OUTFLOW OF WATER

      The watershed for the Canadarago Lake area can be divided  into  four
natural areas, Figure 4, each drained by a creek which flows throughout
the year, and the remaining area, which contains no year-round flowing
drainage system, located primarily on the steep slope east of the  lake.
The former areas constitute 78.2 percent of the entire watershed.
                                   FIGURE 4.
                          CANADARAGO LAKE SUBWATERSHEDS
       From April 15, 1969 through April it, 1970, data were  collected  for
 determining a water balance for Canadarago Lake (16).  Flows of  the  four
 major influent streams, Figure 3, Ocquionis, Mink, Hyder and Herkimer
 Creeks, and the effluent stream, Oaks Creek, were measured using staff
 gauges, set by the U. S. Geological Survey, located near the mouth of  each
 of the influent streams and at the head of the effluent stream.

       The effluent from the wastewater treatment plant for the village of
 Richfield Springs, which flows into Ocquioni's Creek below the gauging
 station and before its entrance to Canadarago Lake, was measured employing
 a 90 degree V-notch weir.

       Using the flow data obtained from these sources, calculations  were
 performed to synthesize a daily hydrograph for each source.  A summary of
 these hydrographs is given in Table 2.
                                    212

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                           Table 2 .  WATER BALANCE FOR CANADARAGO LAKE

                            April 15, 1969 through April 14, 1970
Source Average Flo* Drainage Area
">3/s Percent of Oaks Creek to"2
Oaks Creek \ 2.865 [ 100.0 175.0
Gauged Tributaries
Ocqulonls Creek 0.684 ' 23.9 51-3
Mink Creek ! 0.414 14.5 27.2
Hyrter Creek . 0.375 13.0 27.5
i
Herkimer Creek 0.741 25.8 ' 30-8
Sub Total 2.214 77.2 136.7
Wastewater Treatment Facility 1 0.021 Q.7
Total Gauged Inputs j 2.235 78.0
i i
Percent of Oaks Creek
100.0
29.3
15.5
15.7
17.6
78.1
      Evaporation losses from the  lake  were  estimated  by using surface
water temperature over the same time period  and  climatological data from
Albany, Binghamton and Syracuse, New York  (17).   These data yielded a total
evaporation for the study period of 37,000 m3  (1.3  x 106 ft3), only 0.04
percent of the total annual effluent flow  from Oaks Creek.   During the
summer, the evaporation rate was as high as  two  percent of  the Oaks Creek
flow.  As shown in-Table 2, the gauged  influent  tributary streams accounted
for 77.2 percent of the effluent Oaks Creek  flow and 78.2 percent of its
watershed.  A calculated value of  influent,  equal to the average gauged
area runoff, was assumed for the ungauged  areas.  Examination of the morph-
ology of the lake led to the conclusion that ground water outflows are
negligible.  Oaks Creek flow is, therefore,  approximately equal to the total
water input.

J.  WATER CURRENTS

      Very little study has been made of the water  currents in Canadarago
Lake.  One dye study did, however, indicate  that Herkimer Creek, which enters
the lake at its southern end and near the mouth  of  the Oaks Creek outlet,
may, at times, be shunted into the outlet without having much influence on
the lake.
K.  WATER RENEWAL TIME

      In both 1969 and 1970, the  spring melt  occurred  in late March and early
April.  The peak flows recorded during the  1970 melt,  from the influent
streams are listed in Table 3.  The peak  gauged input  from these four streams
was 33.1 m3 • sec"1 (1169 ft3  * sec"-1-).   The  peak  lake discharge through
Oaks Creek lagged behind the input by four  days and  reached only 18.8 m3
The minimum recorded summer flows in the  four tributaries, also listed in
Table 3, occurred in late August  and early  September 1969.  The minimum flow
in Oaks Creek was 0.048 m3 • sec"1 (1.7 ft3 •  sec"1) and occurred in late
September, nearly one month after the minimum flows  were recorded in the
influent tributaries.
                                   213
sec
   -1

-------
                                   * 3. MAXIWW AK» MIHIMIW IKW> ") IM I'.';'.!

                                     TRlMirTAHlLb M < ,ANAl>AHAr\\ 14, 1970
( t
S^rCt1 '' Ha^lmim Flow j Minimum F
(cfsl I"3/"? , (cfs)
OequlJ-l* ^-sek 2S4 7.95 ^ 0.69
V.i-.K Crtek : 240 6.72 ' 0.16
:-/••«• :r««K 272 7.70 0.10
•i«rjilni«r Cresk 439 12.4 0.10

tlltar/s;
2C
4.i
2.5
2.5
       Because  of  the great variation  in stream  flow  during the  year, the
spring melt  constitutes one  of the major  annual events.   During the
period April  15,  1969  through April 14, 1970, about  43 percent  of  the
lake's total  gauged input and 32  percent  of the gauged output occurred
during the month  of April, when the lake  was not stratified  (16).   As a
result,  the  average lake turnover time during April  was  about 60 days,
whereas  the  annual  average was about  231  days during the  time period in-
dicated.   Based on  31  years  of outflow data from Canadarago  Lake through
Oaks Creek (17),  the average lake turnover  time was  calculated  to  be 217
days.

       A  summary of  the Morphometric Characteristics  of Canadarago  Lake
is  shown in  Table 4 (14).

                           Table 4.   MORPHOMETRIC CHARACTERISTICS OF CANADARAGO LAKE
                      A.  Area

                      B.  Mean Depth

                      C.  Maximum Depth

                      D.  Mean Depth i Maximum Depth

                      E.  Relative Depth

                      F.  Volume

                      G.  Development of Volume

                      H.  Mean Slope

                      I.  Altitude

                      J.  Latitude

                      K.  Longitude

                      L.  Shore Length

                      M.  Development of Shoreline

                      N.  Littoral Development



                      0.  Number of Islands

                      P.  Area of Island

                      Q.  Shore Length of Island

                      R.  Drainage Area

                      S.  Average Outflow


                      T.  Tina of "Flushing"

                      U.  Average Precipitation
759 ha

7.7 m

12.8 m

0.60

0.41*

57.51 x 106m3

1.8

0°36f8" exclusive of island and shoal

390 m

42349'00" North

75°00'25" West

14.4 km

1.47

Town of Richfield Springs) 80% of area
around lake is dsnsely populated with
summer homes

One - Deowongo Island.  One shoal.

3.0 ha

0.8 km

175 km2

2.95 m A calculated from average discharge
for a period of 31 years

217 days

1005 mm
                                         214

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                 LIMNOLOGICAL CHARACTERIZATION SUMMARY
A.  PHYSICAL

    1.  Temperature

        The temperature profile  of  Canadarago Lake for 1968, Figure 5,
is typical for this lake.   It  is observed that the maximum temperature
in the deepest sections of  the lake occurred in September (15°C, 59°F).
It will be noted  that  the Deepest 2jjr meters (8.2 feet) of the lake
seldom exceed a temperature of 15°C (59°F).  During the winter season,
usually from December  through  April,  the lake is covered with a layer
of ice that reaches a  thickness  of  3- meter (20 inches).
                        CANADAMMO
                        10*  II*  20
   FMIME t.
LAKE    IMI  TIMPEKATUftC* I'd
»«•  M"      W  §•   10' ••
                                      UI9UIT 9trTtMCIt OCTOKIt HOVdMfll DICCMU
    2.  Conductivity
        Conductivity measurements of  Canadarago  Lake were recorded as
part of the New York State Water Quality Surveillance Network.   Data
for a five year period (1968-1972 inclusive)  indicated a maximum con-
ductivity of 374.0 i\ mhos •  cm   and  a minimum value of 174.0 u mhos*
    3.  Light Attenuation

        Vertical light extinction  in Canadarago  Lake  was determined from
simultaneous measurements of  surface anr?  subsurface  irradiation with a
submarine photometer.  The readings were  converted to vertical extinction
coefficients (per meter, in base-10 logarithms)  using Table 10 by Sauberer
(19) with estimate^ values of cloud cover and  a  calculated value for the
zenith distance of the sun at true local  time, and the geographical
coordinates (43°N, 75°W), i.e. the elements of the "nautical triangle",
and the procedures of spherical trigonometry (18).  Figure 6 displays
the 99 percent light attenuation depth for white light and the blue,
green, and red regions of the spectrum as measured in 1969 at Station 5»
located in the deepest section of  the southeastern quadrant.

                                   215

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             I «

             * .
                                FIGURE 6.
                     1969 CANADARAGO LAKE LIGHT ATTENUATION
                                STATION 5

K	X    X
                         X	X
                          SCHOTT M 12,
                          439 urn BLUE FILTER


                          tCNOTT V« 9,
                          KHOTT M 2,
                          MO Ml RED FILTER
                 APWL   HAT   JWC   JULY  MNUST KPTCMDI OCTOKR NCWEMn OtCEWtH
    4.  Secchi Disc  Measurements

        Measurements were made  from May through November.  During this
period of time, when measurements were marie at 10 Different locations on
the lake, a depth of greater  than 2 meters (6.5 ft ) was infrequently
recorder?.  The highest reading  recorded was 3.2 meters (10.5 ft  ) and
the lowest reading recorded was 0.9 meter (2.9 ft )  Averaging the readings
recorded from the ten stations,  the highest average reading occurred in
the middle of September, 2.62 meters (8.6 ft ), and the lowest average
reading occurred  in  the  middle  of July, 1.08 meters (3.5 ft).  All readings
were made between 10:00  AM  and  4:00 PM.

    5.  Solar Radiation

        Solar radiation  was measured at Canadarago Lake as part  of the
data recorded by the New York State Automatic Water Quality Acquisition
System station on an hourly basis.  During 1969 the maximum solar radiation
recorded was 1.66 gram calories • cm~2 • hr~l.

B.  CHEMICAL
        The pH of Canadarago  Lake has been measured as part of the New  York
State Water Quality Surveillance  Network,  the New York State Automatic
Water Quality Acquisition  System  and during the New York State Canadarago
Lake Eutrophication Study.  Five  years data (1968-1972 inclusive) from
the Water Quality Surveillance  Network indicates a surface pH of 8.76 as
a high value and 6.9  as  a  low value.  During the Canadarago Lake Eutro-
phication Study, pH measurements  were taken at approximately 14 day in-
tervals during 1968 and  1969  at 10 different stations and, where possible,
at three different depths.  From  this investigation values of pH from a
low of 6.92 to a high of 9.16 were obtained.  A summary of the average
pH of the lake at three different depths is shown in Table 5.

                                   216

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                         Table 5.  AVERAGE pH OF CANADARAGO LAKE, 1968-1969
                         Depth
                         (meters)
                       pH
                    1968	1969
                         0-4.5
                         4.5-8.0
                         8.0-12.5
                    8.12
                    8.03
                    7.26
8.11
7.93
7.66
      2.   Dissolved  Oxygen

          Dissolved  oxygen profile measurements were made at Canadarago
 Lake during 1968  and  1969.  The measurements were  made Curing  the  hours
 of  10:00 AM and 4:00  PM.  A dissolved oxygen profile for 1968  is  shown
 in  Figure 7 (18).   This profile is  typical for  the lake and indicates
 that the bottom 3  m (10 foot) depth of the lake becomes void of oxygen
 from early in July until late September.  The 1935 survey (l)  also re-
 ported  the absence of oxygen in the deepest portions of the lake  at the
 end of  July.
                                       FIGURE 7.
          1968   CANADARAGO  LAKE  AVERAGE DISSOLVED  OXYGEN CONCENTRATION

                            ( port* per million  *  mg /1 )
    0


    9


   10


K  "
UJ
UJ
U.  20
   SB -


   40 -


   48
                               II  10 9
                                                                   10  II
3210
                           01 234 567 8 9 10
        APRIL
                 MAY
                         JUNE
             T       I        i        i        ii
        JULY    AUGUST  SEPTEMBER OCTOBER  NOVEMBER DECEMBER
                                       217

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     3.   Phosphorus

          Phosphorus  Determinations were made on  Canadarago  Lake  samples
collected  at approximately 2 weeks intervals Curing 1968 and 1969.  A
variety  of Different  forms of phosphorus were determined,  including:
orthophosphate,  soluble and particulate phosphorus.   The soluble  and
particulate phosphorus components were separated  by means  of vacuum
filtration through  a  47 mm diameter,  0.8 u membrane filter.   A  summary
of  the average values of  total phosphorus  and the various  phosphorus
forms at three different  depths  of the lake are  shown in Table  6  (18).
              Table b. AVERAGfc CONCENTRATION OF CHEMICAL CHARACTERISTICS 01 CANADARAGO Lr'KE, 1968-1969
   Depth
   0-4,5
   4.5-9.0
   0.0-12.6
   Total Lake
   0-4.5
   4.5-9.C
   9.0-12.6
   Total Lake
   0-4.5
   4.5-9.0
   9.0-12.6
   Total Lak"
   0-4.5
   4.5-9.C
   9.0-12.6
   Total Lake
    0-4.5
    4.5-9.0
    9.0-1?.6
    Total Lake
            1968          1969
            (nlcroqrams per lltor)
                               Depth
Soluble Phosphorus
16.4         13.7
16.2         II.'
25.2         2'-.2
17.2         13.';

Particuiate Phosphorus
31.4         20.1
29.3         30.0
50.0         37.7
32.4         30.5

Total Phosphorus
47.B         42.°
•;5.5         41.3
75.2         t2.<-
49. A         44.4
Organ!: Nitrogen
130P. 4
1122.4
1297
1246.7

Ammonia Mitroqen
70.9
131.3
5»5.5
127.5
764.9
585
573.3
120
14?,. 3
439.1
151.3
       Nitrite and Nitrate Nitrogen
    0-4.5     160.5        125.6
    4.5-9.0    163.4        157.8
    9.0-12.6   192.5        108.2
    Total Lake  163          134.4
        I

       0-4.5
       4,5-9.0
       9.'-12.6
                            1968         1969
                            (milligrams per liter)
                          Soluble Organic ' arbon
                            2.96         4.66
                            2.47         3.59
                            1.40         4.27
                               Total Lai"-   ?.61
                                                   1.41
                         Particular Organic Carbon
                   0-4.5      1.55         1.96
                   4.5-9.0     1.36         1.56
                   a.r-12.,.    1.28         1.37
                   Totil LA   1.49         1.82

                           Total Organic Carbon
                            4.51
                            3.83
                            2.68
                            4.13
                           6.62
                           5.15
                           5.64
                           6.23
        Depth      1968         1969
        (meters)    (micrograms per liter)
                    0-4.5
                    4.5-9.0
                    9.5-12.6
                    Total Lake
Chlorophyll a

 13.3
 12.7
  7.5
 12.5
8.5
6.1
4.9
7.5
Depth
(meters)

0-4.5
4.5-9.1
9.0-12.6
Total Lake

0-4.5
4.5-9.0
9.0-12.6
Total Ldk._
|
0-4.5
| 4.5-9.0
9.0-12.6
Total Lake

0-4.5
4.5-9.0
9.0-12.6
i Total Lake

0-4.5
4.5-9.0
9.0-12.6
Total Lake

0-4.5
4.5-9.0
9.0-12.6
Total Lake
1968
(Milliequivalents
Sodium
0.225
0.247
0.226
0.229
Potassium
0.045
0.038
0.040
0.044
Total Calcium
1.76
1.S5
1.90
l.PO
Magnesium
0.527
0.545
0.461
0.540
Chloride
0.185
0.190
0.184
0.186
Sulfate
0.295
0.304
0.327
0.299
1969
per liter

0.159
0.151
0.189
0.153

0.&

2.78
2.78
3.72
2.84

0.483
0.496
0.614
0.4=0

0.182
0.175
0.214
0.179

0.311
o.sie
0.428
0.342
       4.   Nitrogen

            Nitrogen  determinations were made on  Canadarago  Lake  samples
   collected at  approximately 2  week  intervals during 1968  and  1969.   A
   variety of different  forms of nitrogen  were determined,  including:
   ammonia,  nitrate  and  nitrite,  soluble and particulate-organic nitrogen
   and total organic  nitrogen.   The soluble and  particulate organic  nitrogen
   components were separated by  means of vacuum  filtration  through a  47 mm
   diameter, 0.8 ^ membrane filter.   A summary of the average values  of
   various forms of  nitrogen at  three different  depths of the lake are shown
   in Table 6 (18).
                                         218

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     5.   Alkalinity

         Total  alkalinity  determinations  were  made  on  Canadarago  Lake
 samples  collected at  approximately  2 week  intervals during  1968  and 1969.
 Alkalinity  was determined by  titration with mineral acid  with  time
 allowed  for any suspended calcium carbonate to  dissolve and for  a  stable
 end  point to be attained  (18).  A summary  of  the average  values  of alka-
 linity at three different depths of the  lake  are shown in Table  6  (18).

     6.   Cations

         Analyses for  concentration  of the  cations  of  Ca,  Mg, Na, K and
 Fe were  made on Canadarago Lake samples  collected  at  approximately 2
 week  intervals during 1968 and  1969.  A  summary of the average values of
 these cations  at three  different depths  of the  lake are shown  in Table
 6  (18).

     7.   Anions

         Analyses for  concentrations of the anions  of  chloride  and  sul-
 fate 'were made on Canadarago  Lake samples  collected at approximately
 2 week intervals during 1968  and 1969.   A  summary  of  the  average values
 of these anions at three  different  depths  of  the lake are shown  in Table
 6  (18).

     8.   Trace  Metals

         Copper,  zinc,  cadmium and lead concentrations have  been  measured
 in Canadarago  Lake water  and  sediments to  characterize the  heavy metal
 distribution at the sediment-water  interface.   Composite  epilimnion and
 hypolimnion lake water  samples were taken  in  August 1973  with  a Van Dorn
 type sampler.   Sediment cores and sediment supernatant water were ob-
 tained using a Kajak-Brinkhurst (KB) corer.   Results  showed very low
 concentrations of heavy metals in the lake water,  with cadmium below
 2 }\g  • i~l  and copper,  zinc,  and lead in the  range of 5 to  20  ^g • 1~1.
 Sediment cadmium content  was  less than 10  ^g  '  g~l and lead less than
 20 ^g •  g~l, while copper was in the range of 40-80 ^g •  g"*.  Zinc con-
 tent increased with sediment  depth, ranging from 100^g • g    in the
 0-7.5 cm section of the core  to 275 jjg • g'1 'in the 19.0-26.5  cm section.
 (All analyses  of sediments are expressed on a dry  weight  basis.)

C.   BIOLOGICAL

    1.  Phvtoplankton

        a.   Chlorophyll

            Chlorophyll,, a concentration of Canadarago Lake, was
determined  from samples collected  at approximately  two week  intervals
during 1968 and 1969.   The average  concentration of chlorophyll a that
was determined at three different  depths, are  shown in Table 6.

        b.   Primary Production

            Primary production in  Canadarago  Lake has  been calculated
in terms  of phosphorus and carbon  for the period between May and  December
1969, using an  improved sedimentation trap designed by G. W.  Fuhs  (20).
The contents of the traps  weie analyzed for total phosphorus and  total
carbon,  as well as other parameters.  Tables  7 and  8 present data for

                                 219

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                     Table 7 .  CARBON PRODUCTION 1969 CAN/UARAGO LAKE
Sedimentation
Period

5/9 - 23
5/23 - 6/6
6/6 - 6/20
6/20 - 7/1
7/1 - 7/18
7/18 - 8/1
8/1 - 8/20
8/20 - 9/3
9/3 - 9/15
9/15 - 10/1
10/1 - 10/15
10/15 - 10/31
10/31 - 11/12
11/12 - 12/4


C production -

C

rag/1
57**
105
101
63
38
0
?
25
54
89
63
389
37
191


1166.5
•j

kg/ha
0.08**
0.15
0.14
0.088
0.053
0
?
0.035
0.076
0.1246
0.088
0.5446
0.052
0.267


X 1Q°Q
609 x 104m2 • 195
C- total carbon, top
replicates
(see te
Trophogenic
Zone*
ha
611
633
633
613
620
527
600
588
600
634
671
641
631
533
ave.
609
= i _n fjT
days
minus bottom con^artmcntc
xtj

S A 11
m< tnr
tons, rog/1
49** 1 1 .55
9[J -0.7.v
89 *0.20
54 +0.50
33 0
0 -0.10
^ +0.4
21 -0.8
46 -0.7
79 +1.0
59 +1.1
349 +3.4
33 -4.2
142 +2.7


. m~2 . day "^

of sedimentation

Trophog* me
Zone
xK/*1
40
J4.2
34.8
40
38
35
42
45
43
33
27
33
35
37




ti^p, dv^rag<

At A t'S
mctri' m^ti:1:
torii tons
+62 +111**
-25 +70
+7 +9t
^20 +74
0 + 33
-3.5 -3.3
+17 eit. -5
-36 -15
-30 +16
+33 -112
+ 30 -8'-
+112 -461
-147 -114
-IOC -242
total
1166.5


value of

 i   mid-d«pth 6ita of

 S   sedimentation, represented by CT in st-dimtnt tr.ips (sn- t. xt)

AB  change in bioma^ of CT in ldk<- at 1-3 ro* t. r d. pth

£B*S  iuo oi bioma^i, ehang< and "..fdimtntdtion

 M  coiTfettion obtained from f./\' atoni< ratio', usiritj I' v,.lu. L. in
                    Table  6  .  PHOSPHORUS PRODUCTION  1969 CANADMUGO LAKE
Sedimentation
Period

5/9 - 23
5/23 - 6/6
6/6 - fc/20
6/20 - 7/1
7/1 - 7/16
7/W - 8/1
8/1 - 8/20
8/20 - 9/3
9/3 - 9/15
9/15 - 10/1
10/1 - 10/15
10/15 - 10/21
10/21 - 11/12
11/12 - 12/4


P production =
C production o
P,
US/1
552
1077
525
473
81
628
460
149
314
111
0
3990
2042
-"52


11719 kQ P
609ha • 195
n C/P atonic

g/ha
773
1508
735
662
113
879
644
209
440
155
18
5586
2858
4553



days
ratio
Trophogenic
Zone*
ha
611
633
633
613
620
527
600
588
600
6)4
671
641
631
533
ave.
609
11719 x 106 mo
609 x 10%^ .
basis - 1229.9
S AB
kg ng/1
472
954
455
406
70
463
387
123
264
93
12
3580
1803
24/7
-6.2
+8.4
-9.7
+ 4.4
>2.5
-13.3
+5.8
-•1.5
+ 24.3
-19.7
+14.4
-1.7
-8.2



195 days
10 mgP
x 106Q
Trophogenic

40
34.2
34.8
40
38
35
42

43
33
27
33
35
37


. »-? • day-1
1.0gC • m-2 •
A ' AB+S
kg kg
-248
+ 237
-338
+ 167
+88
-559

+65
+802
-532
+475
-60
-303
+ 224
+ 1241
H27
+237
+551
-172

+330
+990
-520
+4055
+ 1744
+2124
total
11719

day -1
 P_  total phosphorus, top minus bottom compartments of sedimentation trap, average value of
     replicates (see text)

 *   aid-depth area of trophogenic zone

 S   »edi*ent«tionf represented by P. in sediment traps (see text)

AB  change In bio»a&6 of PT in lake at 1-3 meter depth

       *u* of bioaatf. change and sedimentation


                                               220

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the  calculation of primary production via total phosphorus (Py) and
particulate organic carbon (Cy)  determinations.  The  biomass (B) of
phosphorus or carbon in the  lake is that amount retained by a 0.8 u
membrane  filter.  Total phosphorus production yielded 10 mg P ' m  .
Total  carbon production determined from the C/P atomic ratios and
experimentally via the sedimentation traps yielded  1.0 g C •  m   * day   .

        c.  Algal Assays

             A long term bioassay with lake water collected from Cana-
darago Lake in May 1969, and  phosphate additions (but no additional
inoculum)  showed a very clear response to phosphates.   The increase in
biomass with 1 mg ' 1~1 P added  as compared with the  effect of 100
}\g  ' I"!  P indicates a plentiful supply of nitrogen (including organ-
ically bound N) and minor elements.

             Short-term bioassay  studies with   C were run on two days
in 1968.   Additions of nutrients were made to produce the identical
final  concentrations in both  short-term and long-term experiments and
included  K2HP04, NaNC>3, Fe as Fe+  - EDTA chelate,  chelator alone,
unchelated trace metal mix and vitamin mix.  All additions showed stimu-
ulation or inhibition except  nitrate additions which  were always without
effect.

             d.  Identification and Count

                 Phytoplankton from Canadarago Lake  were  sampled and
quantified from 1968 to 1973,  with the exception that during  1970 only
qualitative analyses were performed.   Major plankton  organisms from
the  standpoint of number and  size  were chosen and identified  to genus or
species.

                 Prior to 1968 there  had been massive  blooms of
Oscillatoria prolifica(Grev.)  Gomont in the lake.   Such  blooms recurred
in 1972 and 1973.  The most commonly occurring predominant algae quan-
tified between 1968 and 1973  are shown in Table 9.  During the summer
of  1935 slight shore blooms  were noted in Canadarago  Lake but there
was  never a bloom over the entire lake.  The shore  blooms consisted of
the  blue-green algae Anabaena and Coelosphaerium (l).
                         T»bll 9. MOST CaMONLY OCCURRING PRElXHINAMT ALGAE

                               IN CANADARAGO LAKE, 1966-1973
                            Anacvitlt i3£lli4 Urou.t and Daily
                            a,.lo.i>h..rlji 
-------
    2.  Zooplankton

                Zooplankton sampling was initiated in August 1972 as
part of the Canadarago Lake Eutrophication Project with samples being
collected every two weeks during the ice free season (21,22,23).

        a.  Identification and Count

            Peak abundance for zooplankton during the fall of 1972 was
on October 14, with 179,309 organisms •  m  .   The peak in zooplankton was
due mainly to Eubosmina coregoni (74,944 organisms • m~3) which comprised
42 percent of the total.  Along with the E. coregoni, the cladocerans
made up 70 percent of the population.  From July 6 to July 19,  1973
there was a drastic change in the zooplankton population from 76 percent
composition of rotifers on July 6 to 16 percent composition of rotifers
on July 19; while at the same time, cladocerans made up 13 percent of
the total composition on July 6 and changed to 75 percent composition
of the total number of zooplankton on July 19.  There have been 20
species of cladocerans, six species of copepods and six species of
rotifers identified from Canadarago Lake.  The main pulse of zooplankton
occurred in early July with 311,677 organisms • m~3.  The spring pulse,
typical of many lakes in April and May was not present or was delayed
possibly due to the heavy bloom of Oscillatoria prolifica present in the
lake until mid July.  Changes in the zooplankton population from the
1935 survey (l) appear to be negligible.

    3.  Bottom Fauna

        Monthly benthos samples are collected from seven stations
representing different water column depths and substrates.  Samples dur-
ing a one year period (Sept. 72-Sept. 73) of benthic organisms from the
combined substrates were comprised mostly of chironomic larvae.  The
percent composition of chironomids ranged from a low of 21.5 percent in
September 1973 to a high of 66.2 percent in November 1972.  The only
other group of invertebrates that were numerically important in combined
substrates were the oligochaetes.  The percent composition of these
species ranged from a low of 26.4 percent in November 1972 to a high of
67 percent in July 1963.  The peak in the abundance of bethnic  invertebrates
occurred in March 1973 and was due almost exclusively to chironomide
larvae which, after peak abundance in March,  gradually decreased until
mid July.

        As depth increases, difference in abundance of benthic inverte-
brates becomes apparent.  With a depth of 3 m (10 ft) or greater, the
numbers of oligochaetes decrease as depths increase; however, the percent
composition of oligochaetes appears to remain consistent.  The chironomid
numbers and percent composition decreased with increasing depth, while at
depths of 4.6 m (15 ft) or greater, the numbers and percent composition
of Chaoborus increased as depth increases.  In general, the tot'al
number of benthic fauna decreased as depth increased.

        In 1935 the major organisms below 6 m (20 ft) were Chaoborus
and large chironomid larvae with no mention of the presence of oligo-
chaetes (l).  The 1972 survey samples contained large quantities of
empty mollusc shells indicating that large numbers of clams and snails

                                 222

-------
were at one time present in this lake.  Harman (24) reports that Cana-
darago Lake once supported dense populations of mollusks that are now
severely depleted.

    4.  Fish

        In 1972 a detailed study of the fisheries of Canadarago Lake
was initiated by Cornell University's Department of Natural Resources
(23,25).  This effort is being conducted to measure changes in the
structure and dynamics of fish populations in a highly eutrophic lake
following a reduction in cultural eutrophication with the objective of
developing fish management techniques applicable to lakes undergoing
nutrient control and examine nutrient control as a fish management tool.

        Yellow perch are the most abundant fish in Canadarago Lake.  Other
abundant species are golden shiner, spottail shiner, white sucker, Johnny
darter, black crappie and brown bullhead.  Principal game species are
smallmouth bass, chain pickerel and largemouth basri.  Smelt and black
crappie, recently introduced in the late 1960's, have rapidly expanded
their populations.  Walleye, American eel, banded killifish,bridle
shiner, satinfin shiner, blackchin shiner and blunt-nose shiner have
either decreased greatly in numbers present or are no longer present.
New species reported for the lake are bluegill sunfish, brook trout,
burbot, shortnosed redhorse, fathead minnow and stoneroller.

        Surveys of the Canadarago Lake fish populations during a period
of increasing eutrophication from 1935 to 1972 indicate three species
maintained their dominance throughout the period.  During the 1935 Bio-
logical Survey (l) the golden shiner and yellow perch were the most
abundant forage fish and the chain pickerel the most predominant preda-
tor.  Subsequent surveys in 1958, 1964 and 1969 (26) found the same
species were predominant.

        Table 10 lists the species of fish that have been found in
Canadarago Lake.  Historical records are not adequate to evaluate pos-
sible changes in abundance of all of the species reported from this
lake.

    5.  Bacteria

        No bacteriological studies of major significance have been
undertaken in Canadarago Lake as yet.  Gassing (release of marsh gas)
from sediments, indicative of methane fermentation, can be observed in
the northern half of the lake,  increasing in intensity from mid-lake to
the northern shore.  The phenomenon is observed when an anchor is
dropped from a boat during surveys.  Spontaneous gas release hgs not
been observed, e. g. as gas accumulation in the inverted reference com-
partment of sediment traps.  A preliminary study of sulfate reduction
(27) showed organic matter, not sulfate, to be the limiting factor in
bacterial sulfate reduction in the sediments.  L. W. Wood (28) found
indication of oxidation of Rhodamine B dye in the sediments, presumably
by microbes.
                                223

-------
                                  T.ibU- 111.  C/WN>ARM10 I.AKh H'JI '.PL'.IF,
        Erown trjut--Salmo trutta

        Jhair. rlckfr?l--Esox nijer

        LarJewjth ba5s--Hlcroptgrus salmoides

        Sbal'lauuth bass--M. ^olomieui

        Yellon ctrch-'Perca, flavescens

        Como-, sunflsn—Lecomis aibbotus (punpkinsee^)

        Redbreast sjnfish--L_. aurltm

        Rock ba5S--Ar,bloclvtes ructttrls

        Brown bjllhei'l--lctalurus n»bulosus

        American eel--Anauilla rostrata

        Johnny -»arter--£theostoma n^jjijm olmsteHl

        Ban-«»-i killlfish—FunHulus Hlaehanus

        Bluntnose minnow-Pimephales notatus

        GoHen shiner--Hoteiniaonus crvsoleucas

        Cutlips minnow--Exoalossum maxillinqua

        Common shiner-'llotropis cornutus

        Spottail shiner—N. hu^sonlus

        Bridle shiner—N. bifrenatus

        Satinfin shiner—N. analostanus

        Blackehin shiner~N. heteroHon

Creek chutsijcker — £r^"-«zc' ; c .-.-'•,.;

Rainbow smelt— Osnsr.s aor-'sx

Ifalleve—Stizost ;•*!;- . itraj  .^"i'.m

Northern pika — £53 x l-:'-^^

Muskellunae--Esox T,a3J-.l";"q'.

Burbot— Lota lotj

Brook trout--Salvs?Ii "~:j r.'^ti^al-j

Black crappie--Pomjxi» 'i-ironjc. !.<:. i

Blueqill r.imt'ish--Lei'JiT'.ig '^3C"ro>""-r'. ?
Fallf lsh--Semotllus corporal la

Shorthea^ rf^horse--Moxostoiia m

Stonerol lt?r--Ca">poston\d di'gmjlu

River chub--Ndcomib micropogo."
     6.   Bottom Flora

           No  bottom flora studies  of  major significance  have been under-
taken  in Canadarago  Lake  as yet.   Algae  attached  to  rocks  located  near
shore, October 1973, included:
           CHRYSOPHYTA

           Navicula  sp.

           Cymbella  sp.

     7.   Macrophytes
   CHLOROPHYTA

   Spiroqyra  sp.

   Oedogonium sp.
           Canadarago Lake supports emergent,  floating,   and  submersed
aquatic  macrophytes  around  its  periphery.   The main  species  observed
between  1968  and  1973  are  shown in Table 11.
                                             224

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                         Table 11. CANADARAGO LAKE MACROPHYTE SPECIES,
                           1. Softstem bulrush - Scirpua validus Vahl.
                           2. Harstem bulrush - Scirpus acutus MuM.
                           3. PickerelweeH - Ponte^eria cor^ata L.
                           4. Narrow-leaveH cattail - Typha anqustifolia L.
                           5. Bur reeH - Sparganium eurvcarpufn Engelm.
                        Floating
                           6. Yellow water Illy - Nuphar varieqatum Engelir
                           7. (Hhite) water lily - Nvmphaea o^orata Ait.
                           8. Narrow-1 eaveH ponriweeri - Potamogeton spp.
                           9. Hater milfoil - HvrioohyUum sp.
                           10. MaterweeH - Anach^ris canaHensis (Michx.' Fl.
                           11. Coontail - Ceratophvllum rtgmersum L.
                           12. Ojrly-leaf ponrtweeH - Potamoqeton cri^c'jj "-.
          The plants ranking highest in lake  surface area coverage in
  1968 and 1969 were the two bulrush species  and  yellow water  lily.   The
  location of greatest abundance  of emergent  plants is at the  southwestern
  end of the lake  where hardstem  bulrush, yellow  water lily and  pickerel
  weed predominate.   A great increase in the  amount of submersed vegetation
  occurred between 1969 and 1973.   Water milfoil,  curly-leaf pondweed,
  narrow-leaved pondweed, and water weed predominated.  The submersed
  plants existed around almost  the  entire periphery in water 3 m (10 feet)
  or less in depth.   Areas of greatest density were primarily  in the
  northeastern end,  where milfoil was extremely abundant, and  secondarily
  the southwestern end.

                          NUTRIENT BUDGET SUMMARY
A.   ESTIMATION OF  INPUTS

     1.   Waste Discharges

         There are  no  significant industrial waste discharges in the  Canada-
rago Lake Basin.   There  are two significant sources  of sanitary waste,  the
village  of Richfield  Springs sewage  system and the unsewered homes,  mostly
summer cottages, along the lake shore.

         As noted elsewhere, the village  of Richfield  Springs is served
by a combined sewer system which discharges into Ocquionis Creek  about
840 m (2750 ft) upstream from Canadarago Lake.  Until  1973, the village
had  a primary wastewater treatment plant.   Detailed  estimates of  the
major nutrients discharged from this  source were made  by direct measurement
of the plant effluent, the difference between upstream and downstream
samples  and calculation  from per capita  contributions.   The details  of
these estimates are presented elsewhere  (16).  The results for those major
nutrient studies are  summarized in Table 12.

         Estimation of chemical contributions to the  lake from the unsewered
homes on the lake  shore  is especially difficult.  During the summer  months,
about 1300 people  occupy summer cottages around the  lake shore and are
served by septic tanks and leaching  fields (12).  In 1969 a sanitary survey
of these systems revealed  that 24 percent  of the septic tank systems had
some sort of direct discharge to the  lake, bypassing  the leaching fields (13),

                                     225

-------
       Tat'l. 12. ' ANAHARAGO I AH ' 111 Ml'Al Illl'TT

       mau Rinn n 11> ;,I'R?««> ',< MV  THI ATMI NT I'LAI
            It-
Mo"

-T

N03-+N

NH4-N

Nos

Nop

Nt

Pit
4150

8710

20.030

33

3563

1771

200

5567

2310

343
4.39

0.47

0.23

0.03

0.73

0.30

0.05
 Table 1*. IANADARAGO LAKE fHEMIl'AL INPl/T

FROM SEPTTr TANK AND LEAITIING TILLD SYSTFMS
                 of lak' surfa^ • vr"
   2220

   121
0.29

0.02
  Assuming  that any phosphorus entering a septic  tank leaching field was  re-
  tained in the field*  and  that none  of the nitrogen was retained, Table  13
  was constructed.  No  estimate of  inputs of other chemicals  were made.

      2.  Land Runoff

          The Candarago Lake Eutrophication Study has shown that stream  loadings
  with soluble mineral  species derived mainly from bedrock may be estimated by
  the regression method.   Errors become larger  in the case of constituents
  that are  subject to or products of  biological processes or  that are  in
  particulate form and  therefore subject to sedimentation and sudden dis-
  location  during periods of high flow.

          Utilizing measured stream flows and concentrations, regression
  analysis  was employed to estimate the chemical  runoff  and  lake loading
  from land.  Details of the regression models  are described  elsewhere (29).
  The results of these  estimates are  shown in Tables 14, 15,  and 16.

       3.  Precipitation

           Because of the large ratio  of  the  watershed  area to  that  of the
   lake surface (23:1),  the  contribution  of  chemicals from precipitation  is
  very  small in the  lake, in most  cases less  than two percent, and  can be
  neglected.
                Table 14. HYDROLOGICAL DATA FOR OWUTAriONS OF CHMICAL LOADINGS FRO* C/WADARAGQ LAKE TRIBUTARIES

                                       after Hetllng and Sykes (16)
Xante Drainaoe Ana


Kerk inter creek
Hyder Creek
Mink Creek
Ocg\:ioni« creek
gauged total
Oaks Creek

mi2
11.9
10.6
10.5
19.8
52.8
67.4

ha
3077
2741
2715
5120
13653
17427
MMSU

cf«
26.1
13.2
14.6
24.1
78.0
101
fft Annual Flow isasyred Jnnual Flow

mVs
1.020
0.423
0.581
0.829
2.853
5.144

106i«3/yr
23.3
11.8
13.1
21.6
69.8
90.4
0»»r Drainaq^ Area
m/yr
0.759
0.431
0.481
0.421
0.511
0.519
Cent/ Lhu ted to Lake
m/yr
3.03
1.53
1.70
2.30
9.06
11.74
           Lak* areai 759 ha.
                                          226

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Table 15.   CHEMICAL RUNOFF PER HECTARE Of WATERSHED PER  YEAR1
                               Hyder
                                                   Ocquionis         Gauged
                                                   (except STP)     Watershed
















Na+
K+
Mg++
Cat
F«t
cr
so/
N03"
NOj
NH4+
NOS
Nop
Nt
"o
pst
ppt
cos
Cop
kg
kg
kg
kg
gm
kg
kg
+N02"-N gm
-N gm
-N gm
gm
gm
gm
gm
gm
gm
kg
kg
kg
23.4
11.4
21.1
649
1.27
25.5
222
4350
6.11
477
1130
636
6590
13.9
66.7
105
33.6
6.18
695
1 K+, Mg++, Cl", N03~+N02"-N, NH4*-N
estimated by summation of the prod
tributary. The remaining elements
concentration by the average flow.
16.6
11.6
14.5
617
0.92
22.5
126
5590
5.70
309
861
344
7100
8/15
23.6
134
13.5
4.22
572
28.3 14.3 19.5
11.6 7.8 10.1
24.1 23.1 21.1
701 581 629
0.92 0.76 0.94
42.3 20.7 26.5
196 197 188
5970 4170 4860
7.90 26.0 13.8
444 425 417
2260 1300 1360
424 232 403
9100 6180 7040
23.4 24.7 18.7
47.7 57.2 50.7
125 188 133
20.1 28.0 24.8
4.80 3.29 4.43
655 538 603
















. Nos, Nop, Nt, Pst, and Ppt inputs were
uct of the measured daily flow and the con-
were estimated by multiplying the log mean
Table 16. CANADAHAGO LAKE CHEMICAL INPUT FROM LAND RUNOFF


,+
K+
Mg++
Cat
Fet
ci-
S04=
N02-+'103--N
NO/-N
4
Nos
V
Nt
po
Pst
ppt
Cos
Cop
£C02

Units
gm
gm
gm
gm
mg
gm
gm
mg
mg
mg
mg
mg
mg
mg
mg
mg
gm
gm
gm
PER
Herkimer
9.51
4.62
3.56
263
0.51
10.3
90.0
1760
2.48
193
458
257
2670
5.64
27.0
42.6
13.6
2.51
281
SQUARE METER
Hyder
5.98
4.18
5.24
223
0.33
8.12
45.4
2020
2.06
117
311
124
2560
2.94
8.52
48.4
4. Ht>
1.32
207
OF LAKE
Mink
10.1
4.14
8.61
251
0.33
15.2
70.1
2140
2.83
159
809
151
3260
8.37
l,.l
44.7
7.19
1.72
234
SURFACE PER YEAR
Total Estimated
Gauged Ungauged
Ocquionis Watershed Watershed
9.61 35.2 9.8
5.24 18.2 5.1
15.7 38.1 10.6
392 1129 314
0.51 1.69 0.47
14.0 47.6 13.2
132 338 94
2820 8730 2430
17.5 24.9 6.9
287 751 209
875 2453 682
190 724 201
4170 12700 3520
16.7 33.6 9.3
38.6 91.2 25.3
126.8 262.5 73.0
18.8 44.5 12.3
2.22 7.97 2.21
363 1080 301

TatiJ
Land
Runoff
44.9
23.2
48.7
1440
2. 1C
60.8
432
11200
31.8
959
3135
92t)
16200
43.0
116
336
56.9
10.2
1390
                            227

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    4.  Groundwater

         During our study 78.2 percent of the watershed, including all
significant tributaries, was gauged.  An estimate of nutrient contribution
from the ungauged areas was achieved by assuming that the runoff for these
areas would be equal to the average of the area drained by the tributaries,
not counting the wastewater treatment plant effluent (16).  The total
nutrient input from ungauged sources was thus calculated by dividing the
gauged land runoff by 0.782.  This is groundwater and surface runoff, in
part routed through small and ephemeral streams.

B.  PHOSPHORUS

        Utilizing the monthly average loadings from the gauged sources
and flows from the hydrographs that had been generated, nutrient budgets
for phosphorus and nitrogen were calculated (16).  Phosphorus data have
been given the greatest attention because it was determined that the
algal-limiting nutrient in the lake was phosphorus (30).

        On an annual basis, the principal source of phosphorus in the
watershed was the village of Richfield Springs which contributed 44.1
percent of the total annual input (16).  If computed for the growing season,
June through September, the village's share of the phosphorus input rises
to 66.4 percent.  These figures are equal to about 4.8 g (0.17 oz) P •
day"-*- ' capita"-*- and include commercial as well as domestic sources.  In
determining the contribution of phosphorus from lake shore cottages and
trailers, it was assumed that only failing septic tank systems with direct
discharge into the lake contributed phosphorus.  In 1969, 24.4 percent of
the septic tanks, servicing 317 people on the lake, had some type of direct
discharge into the lake (13).  Using 2.9 g (0.1 oz) P • day'1 • capita'1
(31, 32) for phosphorus production and an average residence time of 151
days (12), the annual phosphorus input from the cottages were estimated
at 140 kg (309 Ibs) P • year'1, or 2.3 percent of the annual total.

        The gauged tributaries carried 42.4 percent of the total phosphorus
input to the lake for an average areal rate of 0.187 kg * yr"1 • ha"1
(0.167 Ibs • yr"1 • acre"1) (16).  Applying the same rate for the area
that did not have gauged tributaries yielded another 570 kg (1257 Ibs)
P • yr'1 for a total of 3120 kg (6880 Ibs) P • yr"1, 51.8 percent of the
total.  During the growing season, when the stream flows became very small,
the streamborne phosphorus was only 23.5 percent of the total summer input.

        Phosphorus inputs caused by rainfall and dustfall were estimated
from literature values.  The reported range was about 0.206 to 0.612 kg
P04 • yr"1 • ha"1 (0.184 to 0.546 Ibs P04 • yr"1 • acre"1) (33), which
suggests an atmospheric contribution of about 100 kg (220.5 Ib) P * yr'1
onto the lake surface itself, less than 2 percent of the total.  The results
of the phosphorus input data are shown in Table 17.

        Similar estimates were made for soluble phosphorus alone.  These
calculations are summarized in Table 17.  Because the wastewater phosphorus

                                   228

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                            Table 18.   ESTIMATED  TOTAL NITROGEN  INPUTS TO CANADARAGO LAKE

                                            April  15,  1969 - April  14,  1970
Source
Village of Richfield Springs
Lake Shore Dwellings
Sub Total
Gauged Tributaries
Ungauge^ Tributaries
Sub Total
Rainfall
Total Input
Oaks Creek Output
Total Value
Percent of
kq/vr Total Value
5730
2020
7750
97350
27100
124450
4200
136400
82500
4.2
1.5
5.7
71.3
19.9
91.2
3.1
100.0
60.5

kq
1920
1630
3550
7660
2130
9790
1100
14440
10400
: Growing
Percent of Annual
Value of Source
33.5
80.7
45.8
7.9
7.9
7.9
26.2
10.6
12.6
Season Values*
Percent of Growing
Season Value
13.3
11.3
24.6
53.0
14.8
67.8
7.6
100.0
71.7
    Net Accumulation anH
       Dissipation
53900
               39.5
                            4040
                                             7.6
                                                                                                     28.3
    *June 1, 1969 through September 30, 1969
                       Table  17.   ESTIMATED SOLUBLE, PARTICIPATE AND TOTAL PHOSPHORUS

                              INPUTS TO CANADARAGO LAKE, APRIL 15, 1969 - APRIL 14, 1970
Source
                      Total  P  Percent of   Soluble P  Percent of  Percent of! Particulate P  Percent of  Percent of
                      (kg/yr)  Total P      kg/yr      Total P     Soluble P   (kg/yr)        Total P     Particulate P
Village of Richfielrf
Springs
Lake Shore
Dwellings
Sub Total i
3augeH Tributaries
JngaugtH Tributaries
Sub Total
Rainfall
Total Input
Oaks Creek Output
Net Accumulation
2660
140
2800
2550
570
3120
100
6020
4660
1360
44.1
2.3
46.4
42.4
9.4
51.8
1.7
100.0
77.5
22.5
2310
121
2431
723
200
923

: 3354
1740
1614
38.4
2.0
40.4
12.0
3.3
15.3

1 55.7
28.9
26.8
68.9
3.6
72.5
21.5
	
350
19
369
1827
6.0 370
27.5 2197

100.0 2566
52.0 2920
48.0 - 354
5.8
.3
6.1
30.3
6.1
36.5

42.6
48.5
- 5.9
13.6
.8
14.4
71.2
14.4
85.6

100.0
113.8
- 13.8
                                                        229

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is about 87 percent soluble, whereas the streamborne phosphorus is only
28 percent soluble, the wastewater contribution to the soluble phosphorus
inputs is very large, amounting to 72.5 percent on an annual basis and
88.6 percent during the growing season.  In addition, Table 17 includes a
value for particulate phosphorus.  Here the soluble phosphorus has been
subtracted from the total phosphorus to yield the value for particulate
phosphorus.  The output of particulate phosphorus is larger than the input.
This may be misleading, however  it is assumed that algae within the lake
converted some of the soluble phosphorus to an insoluble form which accounts
for a larger output than input of particulate phosphorus.

C.  NITROGEN

        The gauged nitrogen contribution from various sources was calculated
in a manner similar to that for the phosphorus contributions.  The waste-
water treatment plant loadings for soluble organic nitrogen were deduced
from Ocquionis Creek data.  The remaining wastewater data were based on
raw wastewater analyses (16).

        About 62 percent of the wastewater nitrogen was in the form of
ammonia, and another 31 percent was present as soluble organic nitrogen (16).
In contrast, about two-thirds of the nitrogen in the tributaries was either
in the form of nitrite or nitrate, therefore, there are qualitative as well
as quantitative differences among the nitrogen sources.

        Estimates of the different nitrogen sources are given in Table 18.
The village contribution is equivalent to about 10.3 g (0.363 oz) N * day"  .
capita"! and seems to be a result of domestic activities only.  The same per
capita rate was taken for the lake shore residences.  This time it was
assumed that the nitrogen was not retained in the septic tank leaching fields,
so the contributing population was taken as the entire lake shore dwelling
population of 1300 people.  The data indicated that human wastes were a
minor source of nitrogen input to the lake and were the same order of magnitude
as rainfall and dustfall.  The atmospheric rate was taken to be 1.50 kg
N • yr"1 ' ha"1 (1.34 Ibs N • yr"1 • acre"1) (33, 34).

        The principal sources of nitrogen were the tributary streams, which
accounted for approximately 91.2 percent of the annual input.  The predomi-
nance of the tributary streams is marked, even during the summer months when
over two-thirds of the nitrogen input is transported by streams.  The aver-
age annual nitrogen loading carried by these streams was 7.10 kg N • yr"1 *
ha'1 (6.34 Ib N • yr"1 • acre"1).

D.  MISCELLANEOUS ELEMENTS

        Summary data for chlorides, magnesium and potassium that were deter-
mined during the study period, April 15, 1969 through April 14, 1970 are
given in Table 19 (16).  In each case, the contribution of these materials
from wastewater were relatively minor.
                                   230

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                                                                                         T«bl» 19.  GAUGED MISCELLANEOUS UTUTS NO OUTPUTS TO CAHADMtfO UKE
                                                                                                        April 15, 1969 through April  14, 1970
                                                                                                                   I.  Pot ••111*

Tlw Period

April 15-30, 1969
Hey 1969
June 1969
July 1969
August 1969
Septe^er 1969
October 1969
(lovelier 1969
December 1969
January 1970
February J970
March 1970
April 1-14,1970
Average


Tine Period

April 15-30, 1969
Hay 1969
June 1969
July 1969
August 1969
September 1969
October 1969
November 1969
December 1969
January 1970
February 1970
torch 1970
April 1-14, 1970
Average


Tine Period

April 15-30, 1969
Mty 1969
June 1969
July 1969
Augu*t 1969
September 1969
October 1969
Nc-ve^er 1969
OeceAer 1969
January 1970
February 1970
(torch 1970
April 1-14, 1970
Average
I
i

356
106
104
37.9
13.3
6.0
14.1
131
125
82.7
128
85.4
636
109




909
343
335
150
65.0
34.9
68.4
404
393
294
402
289
1430
324




985
273
271
926
30.6
13.1
32.5
345
327
210
334
218
1820
291
Qua
Inou
n
215
72.9
81.0
25.2
9.4
4.7
14.5
120
116
56.5
B9.7
67.9
574
86.1
b.
Qua
Inou
Mink Creek
431
160
175
60.0
23.9
12.9
36.0
251
244
131
194
149
1050
179
c. Chlo
On

JIlnLCfreek, 	
729
297
320
121
52.1
30.1
76,0
443
435
249
355
278
1630
315
itltv of Potas


213
62.9
76.1
16.6
5.8
2.6
6.5
113
102
49.7
98.0
57.7
788
66.9
Ifegtwilua
tltv of Maane


265
84.5
100
24.1
8.69
4.31
10.1
145
133
66.2
104
77.9
900
109
rl*.
tltv of Chlor

Hvder Gteek
413
114
140
27.7
9.06
5.65
10.3
215
190
87.9
142
104
1670
169
Hum (ka * H.V1)

1 Hmi-r Cteek
184
72.3
84.5
30.0
11.1
6.3
21.9
176
125
64.4
99.3
99.6
632
96.1

slum (ka • d»Vll


343
132
156
55.4
204
11.6
40.3
326
232
119
164
147
1160
178

de (kg • 4CV*1)

Herki^r Creek
412
157
167
65.5
24.0
13.5
47.7
394
279
142
220
176
1440
215

Outout

2544
1064
689
227
74.3
16.6
142
845
865
536
871
497
3018
713


OutDut

3390
1550
1020
370
133
36.1
240
1230
1270
817
1270
763
3940
1020


OutDut
O.k. Creek
5690
2430
1540
508
166
41,6
317
1890
1940
1200
1950
1110
6750
1600
f
231

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                              DISCUSSION
A.  LIMNOLOGICAL CHARACTERISTICS

        Canadarago Lake  shares many of its features with its western
neighbors, New York's Finger  Lakes,  and with many other lakes located
between 40 and 60 degrees  latitude.

        The climate at 43°N and  75°W is neither humid nor arid and in
this respect resembles many areas  in northern to southeastern Europe.-
The region is somewhat sheltered from the Atlantic Coast but is readily
exposed to rain and snowstorms originating in the Gulf of Mexico and
certainly exposed to those from  the St. Lawrence Great Lakes.  At 43°N
on the North American Continent, winters are relatively severe and com-
parable to Europe at 6QON  or, in eastern Europe, in the fifties.  Ice
cover on Canadarago lasts  from December through April and reaches a
thickenss of 3- m (20 in.).  Summers are as warm as in comparable latitudes
of Europe, causing considerable  warming to the bottom of lake of Canada-
rago 's depth, 12.8 m (42 ft).  Correspondingly, the annual cycle of
Canadarago is characterized by a very short period of spring overturn which
may be preceded by an algal bloom  developing under the ice.  Stratification
proceeds in a typical manner, and  since warming at the bottom is substantial,
16°C (28.8°F), breaks down early (in September) when the water is still
warm enough to support considerable primary production.  After a prolonged
cooling period in autumn,  winds, to which Canadarago is well exposed, may
not permit the formation of an ice cover until the entire lake is cooled
down to somewhere between  4°  and 0°C (39 and 32°F), and the stability of
winter stratification varies  accordingly.

        Located in hilly terrain,  the morphometry of the lake is not
unusual (Table 4).  Hydrologic conditions and the size of the watershed
provide for a mean retention  time  of 217 days.

        The basic chemistry of Canadarago Lake is summarized in Figure 8.
Calcium and bicarbonate  ions  predominate, followed by magnesium and sulfate
ions.  Sodium and chloride ions  are nearly matched.  Sulfur springs in
.the vicinity of the lake account for part of the sulfate and may account
for the fact that in spite of the  eutrophy of the lake, bacterial sulfate
reduction is not limited by sulfate but by the organic carbon source (27).
The calcium balance of the lake  is such that extensive precipitation of
this element must occur, particularly during productive periods in summer.
Epilimnion calcium concentrations  are about 0.5 meq • 1   lower than those
found in the tributaries.  Similarly, iron is precipitated and presumably
plays an important role  in the ultimate deposition of phosphate.
                                   LAKE CANADARAGO
                               RELATIVE IONIC COMPOSITION
                                    (LAKE AVERAGE)
                                                 JULY 23,1968
                           HCO,-
                                                       C«**
                 Figure 8. Canadarac/o Lak^. rnlativp Ionic canposit ion. Miaqram after Manclia
                       shows shafifMj arnas proportional l.o <-onc«*nt rat iong  Reprint <*d from 30.
                                    232

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        Conditions  for primary productivity are favorable and until recently
were enhanced  by substantial inputs of  nutrients from untreated  sewage.
Although wind  exposure and basin shape  would suggest excellent mixing,
the lake has exhibited, from time to  time,  a slight but significant
gradient in characteristics such as chlorophyl and particulate phosphorus
and other parameters expressing biomass,  indicating greater productivity
in the northern  part which is not only  more shallow but also received the
discharge of untreated sewage.  In agreement with this observation, the
sediments in the  northern part have greater organic content and,  upon in-
cubation under aerobic conditions, release  soluble phosphorus in  greater
amounts.

        The principal limiting nutrient in  the lake is phosphorus as
indicated by:

        1.  The  atomic ratios of the  major  nutrients in the tributaries
            (Table  20).

        2.  The  disappearance of reactive phosphates from the epolimnion
            during  most of the growing  season (Figure 9).

        3.  The  relative chemical composition of the plankton
            (C:N:P  ratios, Figure 10).

        4.  Long  and short-term bioassay  (see Section IV).
                  C:M
 HwUmr CrMfc
                  MM
»•* CrMk

Ocqulonfci CrMk
                  M2
 Ocqutonto * STP •Mm*   Ml
	fclMt
                  m
K

•I

92

It
                            1)
 Tibi* ». Tributtrlti to Candtrtgo Ukt atonic

       ratio* CiNiP (P>1). lUprlntM fro* 30.
                                  Figure 9. soluble phosphates and foms of nitrogen in canadarago Lake, 1969.
                                        Reprinted from 30.
                                   233

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                          M   J
                 Figure 10. Elementary composition of participate matter in Canadarago Lake,
                       summer 1969.  ordinates scaled according to the atomic ratios
                       C:N:P - 106:16:1.  Reprinted from 30,
        Nitrogen  is  present as nitrate except in late summer  when  ammonia
is the only  available form (except organically bound nitrogen)  but both
are found  in  concentrations that can be considered higher  than  limiting.
Among the  Cyanophyceae,  the Chroococcales and Oscillatoriales are  predomi-
nant, and  one possible nitrogen fixing form, Aphanizomenon, occurred  during
short periods which  were definitely not caused by nitrogen depletion.
Carbon dioxide depletion can occur in a spotty fashion during summer  after-
noons.  The  thesis that  such a condition favors the development of blue-
green algae  is not generally supported by observations in  Canadarago  Lake.
Blue-green algal  blooms  do occur in summer, but the same species were found
to produce blooms in winter, in early spring, and immediately after fall
overturn.  Simulation of growth by the availability of phsophorus  in  the
presence of high  concentrations of C02 is a more likely explanation of these
blooms.

        Silicon depletion may affect species composition in Canadarago Lake.
Silicon has been  a neglected element in the earlier studies on  which  this
report is  largely based.   Data on this element are now being  gathered.
Iron appears  to become limiting at times when the solubility  of the element
is affected by high  pH which in turn is caused by phosphate eutrophication.
Other forms of nutrient  limitation were looked for but were not discovered.

        A  strange and thus far unexplained phenomenon is the  reoccurrence
of blooms  of  Oscillatoria prolifica, a red-colored member  of  the blue-green
algae, in  summer  and in  winter from 1972 until 1973-74.  This alga was
predominant also  until  1967-68,  and was the cause for many citizen's  com-
plaints.   In  the  intervening years, the algae was scarce and  never developed

                                   234

-------
a bloom.  The effect of this bloom on the food chain deserves study because
much grazed-upon populations of green algae are virtually absent when
0. prolifica blooms, and the collapse of 0. prolifica blooms is followed
by periods of great clarity of the water, suggesting the presence of sub-
stances inhibitory to the growth of other algae.

        The antagonism of rooted aquatics and plankton algae is another
object for study.  Macrophytes, more predominant 40 years ago then they
are now, may gain as algal growths are controlled by phosphate removal
from sewage, and indications to this effect are seen.

        A more complete assessment of secondary production and fisheries
will emerge as the Canadarago study progresses.

B.  DELINEATION OF TROPHIC STATES

        Canadarago Lake is eutrophic by all criteria employed.  The
hypolimnion becomes depleted of oxygen during the summer.  The lake carries
algal blooms with great regularity although species composition of the
blooms, duration, and time of year can vary from year to year.

        Productivity during the 1969 season (May-November) was 1.0 g C •
m~2 • day~l, a value also observed in eutrophic Lake Erken, Uppland,
Sweden (35).

C.  TROPHIC STATUS vs NUTRIENT BUDGETS

        Phosphorus loading on Canadarago Lake is 0.8 g • m~2 * yr"1.  If
Vollenweider's (35) representation of phosphorus loading and mean depth is
expressed numerically as follows:

        E = 40 -  L - 2'0'6

Where:  L = P loading (g • m~^ * yr"1)    Z = mean depth (meters)

lakes with EO would tend to be oligotrophic, and those with E>2 eutrophic.
Canadarago with 2 = 7.7 m gives E = 9.4, in agreement with its eutrophic
conditions.  This statement requires that the mean residence time in the
lake is sufficient to allow complete conversion of phosphate inputs to biomass.
With a theoretical retention time of 217 days, this condition is met.   It
is also seen that even after reduction of phosphate inputs to 3800 kg
(6020 kg less 90  percent of 2660 kg,  Table 17),  by improved sewage treat-
ment, Canadarago  Lake is likely to remain eutrophic (loading of
0.51 g P •  m~2 •  i~l,  E = 6.0).   Canadarago Lake,  therefore,  appears to
be a naturally eutrophic lake,  a condition regularly found in lakes in a
reasonably average setting with regard to nutrient runoff, which are
characterized by  a similar mean depth and,  related to this,  similar or
larger ratios of  littoral and deep water area and  of epilimnic and hypo-
limnic volume.
                                   235

-------
            Another representation proposed  by Vollenweider (36) involves
    utilization of flushing time.  In  this representation a plot of phos-
    phorus loading (g P  • m~2  « year"-'-)  vs mean depth (m) divided by detention
    time (years) is constructed.  Applying this to Canadarago Lake, with
    phosphorus loading equal to 0.79 g P • m~2 •  yr"1,  and flushing time
    equal to 0.595 years, the  plot of  loading  vs mean depth divided by re-
    tention time results in a  point that lies  above the dangerous line,
    indicating that Canadarago Lake is eutrophic by this evaluation.

            The retention of phosphorus  in Canadarago is rather low, even
    for a eutrophic lake, 22.5 percent over  the year April 15, 1969-April 14,
    1970, or 59.1 percent over the growing season June 1-September 30, 1969
    (see e.g. Ref. 37).  Figure 11 shows that  inputs account for only 10 percent
    of the seasonal production in terms  of phosphorus as determined by the
    sedimentation technique.   This means that  incoming phosphorus was utilized
    approximately 10 times before it was lost  by flushing or, to a greater
    extent, by deposition.  Much of this recirculation of phosphate occurred
    during fall overturn.  Erosion of  the thermocline during summer may be
    a contributing factor as in Lake Mendota (38) but increasing exposure
    of the lake bottom accompanies this  and  its effects may exceed those of
    thermocline erosion, Figure 12.

            By fall of 1974 Canadarago Lake  showed clear signs of recovery
    from phosphate eutrophication after  phosphate removal was instituted at
    the Richfield Springs Wastewater Treatment Facility approximately two
    years earlier.
              TTT •  S ' 0 ' N r
Figure iJ. E*cess ol input over output (lower curve) and total produ<
    Canaaaraqo Ltke, measured aa phosphorus, 1969 data.
                                                                     by a O.x-yi numl'i a
                                       236

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                                 SUMMARY
        For the past seven years, New York State's Departments of Environ-
mental Conservation and Health have been conducting a technical investi-
gation on Canadarago Lake, and its tributaries, at Richfield Springs, New
York as part of the State's program on lake eutrophication.  Portions of
these data have been included in more than 30 different publications.

        Canadarago Lake is situated in East Central New York in the Susque-
hanna River watershed.  The surrounding terrain is hilly with ground elevations
from 396 m (1300 ft) to 579 m (1900 ft).  The lake's drainage area encom-
passes 175 km2 (67.5 sq mi) with four major tributaries draining 78.3 percent
of the watershed.  The bedrock of the basin is predominantly limestone in the
north and shales and siltstones in the south.  The soils of the area consist
of glacial deposited materials with some isolated recent alluvial deposits.

        The permanent population of the lake basin is about 3500 people.
Additionally, approximately 1300 people occupy lakeside cottages during
the summer.  About 49 percent of the watershed is devoted to agriculture,
primarily dairy farms, and 34 percent is in forest or brushland.  The lake
is used primarily for recreational purposes.

        Canadarago Lake is nearly 6.4 km (4.0 mi) long and is 1.9 km (1.2 mi)
wide at its widest point.  The mean depth of the lake is 7.7 m (22 ft) with
the maximum depth being 12.8 m (42 ft).  The lake has 759 ha (2050 acres)
of surface area and 14.4 km (9 mi) of shoreline.  The lake has a poorly de-
fined thermocline which is seasonally found at 6 to 8 m (20 to 26 ft) depth.
The epilimnion accounts for about 72 percent of the lake volume from June
to September.  The average hydraulic retention time of the lake has been
calculated at 217 days.  The lake is ice-covered from December through April.

        The depth of 99 percent attenuation of white light averages about 7
meters (23 ft) with the Secchi disc depth ranging seasonally from 1 to 3 m
(3.3 to 10 ft).   The pH is commonly above 8,  with pH's above 8.5 occasionally
observed in May and September.  Dissolved oxygen in the top 6 m (20 ft)
averages about 10 mg •  1~* from May to November, but the region below 11 m
(36 ft) becomes anoxic from the middle of July to the end of September.

        Total phosphorus averages about 50 L\g •  I"-*- with about 50 percent
of this being soluble.   Summer orthophosphate phosphorus is below 5 ^g • 1"
in the surface water,  but commonly exceeds 50 ug •  1~1 in the anoxic deep
region during August and September.   Ammonia  nitrogen averages 150 ug •  1  ,
and nitrate plus nitrite nitrogen drops from over 500 ug •  I"-- in spring to
less than 50  g •  I"* from July to November.
        Total organic carbon is about 5 mg •  1~1 of which about two-thirds
is soluble.   The highest levels of dissolved  organic carbon occur in the

                                  237

-------
euphotic zone Curing May and June.  The lake water can be considered a
moderately hard water lake.  Calcium carbonate precipitation occurs to a
measurable extent.

          The highest chlorophyll a concentrations exist in the top 5 m
(16.4 ft) with the average concentration Curing 1968 and 1969 being about
10 jvg • 1~1.  Mean primary production is about 1 g carbon • m~2 • day'l.
Algal assays have indicated that phosphate and iron - EDTA innocula sig-
nificantly increased CC>2 fixation while nitrate additions were always
without effect.  Cyanophyta dominate summer plankton samples while
Chrysophyta are most common in spring and fall.  Common phytoplankton
include Aphanizomenon flos-aquae, Anacystis incerta, Stephanodiscus
niagarae, Cyclotella comta, Sphaerocystis schroeteri, Ceratium hirundinellat
and Trachelomonas spp.  The common zooplankton include Eubosmina, Paphnia,
and Diaptomus with the assemblages evenly divided between Cladocerans and
Copepods.  Chaoborus and six genera of rotifers have also been identified.

          The benthic fauna consists primarily of Chirpnomidae with the
remainder primarily Oligochaetes.  Ongoing fish studies indicate yellow
perch and golden shiner to be the most common pelagic fish and chain
pickerel the most predominant predator although a total of 40 species have
been identified.  No microbiological work has been attempted, but benthic
algae and aquatic macrophyte communities have been characterized.

          The prime emphasis of this project has been to develop nutrient
budgets for the biologically important chemical elements and to relate the
budget to the trophic status of the lake.  From April 1969 to April 1970,
44.1 percent of the phosphorus input entered the lake from the Richfield
Springs Sewage Treatment Plant, 42.4 percent from the lake's four major
tributaries, 9.4 percent from the ungauged portion of the watershed,
2.3 percent from lakeside dwellings and 1.7 percent from direct precipi-
tation on the lake surface.  The net accumulation of phosphorus in the
lake during this period (inputs minus outflow) was 790 kg/yr (2742 Ibs/yr).
A major portion, 68.9 percent, of the soluble phosphorus entered the lake
from the Richfield Springs Sewage Treatment Plant.  In contrast, 91.2
percent of the total nitrogen input during the same period resulted from
stream discharge.

          The phosphorus loading has been calculated to be 0.8 g • m~2 • yr~l,
Following Vollenweider's work, the lake should be considered eutrophic
and indeed it is.

          During 1972, a modern wastewater treatment facility was constructed
to replace the existing sewage treatment plant at Richfield Springs.  The
new plant provides phosphorus removal, and preliminary results indicate
that the problem of cultural eutrophication seems to be lessening in
Canadarago Lake.
                                   238

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                               REFERENCES
 1.  Tressler,  W.  L.  and Bere,  R.,  "VIII  .A.  Limnoligical  Study of  Some
     Lakes in the  Delaware and  Susquehanna Watersheds", A Biological
     Survey of the Delaware and Susquehanna  Watersheds, Biological
     Survey (1935) No.  X, Supplement to the  25th  Annual Report,  1935,
     State of New  York  Conservation Department, 222-236  (1936).

 2.  Flint, R.  F., "Glacial Geology and the  Pleistocene Epoch",
     John Wiley and Sons, Inc., New York,  589 p.  (1947)

 3.  "Preliminary  1970  Population Data, U.S. Census",  U.S.  Government
     Printing Office, Washington, D.C.

 4.  "U.S. Census  for 1960", U.S. Government Printing  Office,
     Washington, D.C.

 5.  "U.S. Census  for 1950", U.S. Government Printing  Office,
     Washington, D.C.

 6.  "New York State  Land Uses  and  Natural Resource  Inventory",  Center
     for Aerial Photographic Studies,  Cornell University,  Ithaca,  New York

 7.  Boulton, P.W., "Land Use in Canadarago  Lake  Watershed", unpublished
     data, New York State Department of Environmental  Conservation,
     Albany, New York

 8.  Wright, S.K., "Canadarago  Lake Watershed Land Usage",  unpublished
     data, State Soil and Water Conservation Committee, Cornell  Univer-
     sity, Ithaca, New  York

 9.  "1964 Census  of  Agriculture -  Herkimer  County", A.E.  Ent. 475-20,
     Dept. of Agriculture Economics, New  York State  College of Agriculture,
     Cornell University, Ithaca, New York

10.  "1964 Census  of  Agriculture -  Otsego County", A.E. Ent. 475-20,
     Dept. of Agriculture Economics, New  York State  College of Agriculture,
     Cornell University, Ithaca, New York

11.  Kling, G.F.,  "Relationships among Soils, Land Use, and Phosphorus
     Losses in a Drainage Basin in  East-Central New York  State".

12.  "An Analysis  of  the Contribution of  Canadarago  Lake  Recreational
     Properties to the  Economy  of the Richfield Spgrings-Schuyler Lake
     Area", Soil Conservation Service, U.S.  Dept.  of Agriculture,
     Syracuse,  New York (1970)

13.  Smith, P.J.,  Cunnan, J.F., VanCleef, T., and Hamm, R., "Report  -
     Canadarago Sanitary Survey", Oneonta  District Office,  New York  State
     Department of Health (1967)
                                  239

-------
14.   Carcich,  I.G.,  "Canadarago Lake  Morphometric  Data", unpublished,
     New York  State  Department of Environmental  Conservation,  Albany,
     New York

15.   "Climatological Data",  U.S.  Department  of  Commerce,  Washington,
     D. C.,  (1951 through 1960)

16.   Hetling,  L,J. and Sykes,  R.M ,  "Sources of  Nutrients in Canadarago
     Lake",  Journal  Water Pollution  Control  Federation,  4,  No.  1,  145(1973'

17.   "Climatological Data",  U.S.  Department  of  Commerce,  Washington,
     D.C. (1951-1972)

18.   Fuhs,  G.W., Allen, S.B.,  Lyons,  T.B.  and LaRow,  E.J.,  "Canadarago
     Lake Eutrophication Study, Lake  and Tributary Survey,  1968-1970",
     Technical Paper No. 18, New York State  Department of Environmental
     Conservation (1972)

19.   Sauberer, J. Mitt. Int. Ver. Limnol.  No. 11,  (1962)

20.   Fuhs,  G.W., "Improved Device for the  Collection  of Sedimenting
     Matter",  Limnol. Oceanoqr. 18,  989-993  (1973)

21.   Green,  D.M., "Fisheries Investigation of Canadarago Lake - Quarterly
     Report for July-Sept. 1972", Department of  Natural Resources, N.Y.
     State College of Agriculture and Life Sciences,  Cornell University,
     Ithaca, N.Y. (1972).

22.   Green,  D.M., "Fisheries Investigation of Canadarago Lake - Quarterly
     Report for Oct.-Dec. 1972",  Department  of  Natural Resources,  N.Y.
     State College of Agriculture and Life Sciences,  Cornell University,
     Ithaca, N.Y. (1973).

23.   Green,  D.M. and Smith,  C.B., "Fisheries Investigation of Canadarago
     Lake,  Revised".  A Proposal, Department of  Natural Resources, Cornell
     University, Ithaca, N.Y.  (1973).

24.   Harman, W.N., "The Mollusca of  Canadarago  Lake and a New Record  for
     Lasmigona Compressa (Lea)",  The  Nautilus,  87, No. 4, 114 (1973).

25.   Forney, J.L., "Fisheries Investigation  of  Canadarago Lake".  A
     Proposal, Dept. of Natural Resources, Cornell University, Ithaca,
     New York (1972).

26.   New York State Department of Environmental  Conservation,  Region  IV
     Files,  1958, 1964, 1969.

27.   Fuhs,  G.W. and Rhee, G.Y., Unpublished  data,  New York State Depart-
     ment of Health, Albany, N.Y.

28.   Wood,  L.W., Unpublished data, New York  State  Department of Health,
     Albany, New York
                                  240

-------
29.  Hetling, L.J., Harr, I.E., Fuhs, G.W. and Allen, S.P., "Phase I,
     Canadarago Lake, Otsego County, New York" Technical Paper No. 34,
     New York State Department of Environmental Conservation (1974).

30.  Fuhs,G.W., Demmerle, Susanne D., Canelli, E., and Chen, M.,
     "Characterization of Phosphorus-Limited Plankton Algae (with
     reflections on the limiting-nutrient concept)".  In: Nutrients
     and Eutrophication, Amer. Soc. Limnol. Oceanogr. Spec. Symp.
     No. 1, 113-133 (1972).
                   M                          it     it
31.  Manczak, H., "Uber die Auswertung von Gewasserguteuntersuchungen",
     Vom Wasser, 35, 237-265 (1968)

32.  Watson, K.S., Farrell, P,R., and Anderson, J.S., "The Contribution
     from the Individual Home to the Sewer System", Journal Water Pollution
     Control Federation, 39, 2039 (1967)

33.  Weible, S.R., "Urban Drainage as a Factor in Eutrophication", In
     Eutrophication: Causes, Consequences, Correctives,  National Academy
     of Science, Washington, D.C. (1969).

34.  Hetling, L.J., and Carcich, I.G., "Phosphorus in Wastewater",
     Water and Sewage Works, 120, No. 2, 59, February (1973)

35.  Vollenweider, R.A., "The Scientific Basis of Lake and Stream
     Eutrophication, with Particular Reference to Phosphorus and
     Nitrogen as Eutrophication Factors", Tech. Rept. to OECD,  Paris,
     DAS/CSI/68, No. 27 (mimeogr.) 182p. (1968)

36.  Vollenweider, R.A., "Input-Output Models", Canada Centre for Inland
     Waters, Burlington, Ontario, Canada

37.  Thomas, E.A., "Sedimentation in oligotrophen und eutrophen Seen
     als Ausdruck ihrer Produktivitat", Verh.  Int. Ver.  Limnol., 12
     383-393 (1955)

38.  Stauffer, R.E., and Lee, G.F.,  "The Role  of Thermocline Migration
     in Regulating Algal Blooms", In Modeling  the Eutrophication Process.
     Proceedings of a Workshop held at Utah State University,  Logan,
     Utah,  Sept. 5-7,  1973.  E. Joe Middlebrooks, Donna  H. Falkenborg
     and T.E. Maloney, eds. Logan, Utah, Utah  Water Research Laboratory,
     Utah State University, p.  73-82 (1973)
                                  2A1

-------
                            SECTION IV - OHIO

                 LIMNOLOGICAL AND GEOCHEMICAL CHARACTERISTICS
                      OF THE TWIN LAKES WATERSHED, OHIO

                     G. Dennis Cooke, David W. Waller,
                   Murray R. McComas and Robert T. Heath

            Center  for Urban Regionalism and Environmental  Sciences
              and Departments of Biological Sciences  and Geology
                           Kent State University
                                 Kent, Ohio
                               I.  INTRODUCTION

     The Twin Lakes Watershed is a heavily urbanized ecosystem with three cul-
turally eutrophic glacial lakes and four small upland, manmade ponds  (Cooke,
et al. 1973).  In 1973, sewage (septic tank) diversion was essentially com-
pleted.  The Twin Lakes Project was established in late 1971 to measure the
response of the two main lakes (East and West) to diversion, and to investi-
gate the efficacy of phosphorus precipitation by aluminum sulfate as  a means
of accelerating recovery.  Monitoring data for 1972-1974 from that project
(EPA 16010 HCS, R801936) is reported here.

     Methods of measurements for hydrologic, geological, and limnologic data
are given in Section IV.

                   II.  GEOGRAPHIC  DESCRIPTION  OF WATER BODY

     A.  Latitude and  Longitude.  These data are listed in Table 1.
     B.  Altitude Above Sea Level.  These data are listed in Table 1.
     C.  Catchment Area.  These data are listed in Table 1.
                                  Table 1.
      Morphological and Hydrological Data of the Twin Lakes Watershed
Latitude-Longitude
Area of Watershed (ha.)
Population Estimate  (1975)
41° 12' N. Latitude, 81°
334.5  (including lakes)
1510 (452/km.2)
Area  (ha.)

Maximum length  (km.)
Maximum width  (km.)
Volume (m3)  (V)

Maximum depth  (m.)
Mean  depth  (m.)
Elevation  (m.)
Water renewal  time
  (yrs.) (=V/Q)

Area  of other  lakes in
  in sub-watershed
      West  Twin Lake
           34.02
(including  canals  § lagoons)
            0.65
            0.60
        14.99 x 105
(including  canals  § lagoons)'
           11.50
            4.
    34
318.73
 1.
 1.
 1.

15
              64
              81
              03
       (1972)
       (1973)
       (1974)
                                   21 '  W.  Longitude
                               East Twin Lake
                                    26.88

                                     0.85
                                     0.50
                                13.50 x 105
 12.00
  5.03
318.42
  0.79 (1972)
  0.93 (1973)
  0.58 (1974)
*These shallow  areas are  excluded  from  calculations  of mean  concentrations
and amounts of  nutrients.
                                     242

-------
    D.  General Climatic Data.  Portage County has a humid-temperate
continental type climate with an average frost-free season of 168 days.
Average dates of spring and fall killing frosts are May 2 and October 17.
Average January temperature is -3°C, the average July temperature 21.8°C.
Temperature extremes are 39°C and -30°C (Ritchie and Powell, 1973).
Insolation has not been measured.
    Precipitation-evaporation data for 1972-74 is summarized in Tables
4 and 50  The highest occurred in September 1972 with 20.7 cms. and
one storm of 9.1 cms.  Highest evaporation occurs in June-August.

    E.  General Geological Characteristics.  Geologic materials in
the watershed are comprised of up to 45.7 meters of deposits overlying
sandstone bedrock.  The Twin Lakes are situated on the axis of a buried
bedrock valley (Winslow and White, 1966), filled with outwash deposits
of silt, sand and gravel derived from the Kent Ice advance, which occurred
about 15,000 years ago.  The western belt of the deposits left by the
Kent moraine is composed of a high proportion of sand and gravel.  Kettle
holes are common.  The deepest are sites of ponds and lakes, including
Twin Lakes.  Earth materials surrounding the lakes are sand and fine
gravel on the uplands, silts and organic soils in the undrained depression
areas.  Underlying sand and gravel is gray silt varying in thickness
from 3 to 10 meters.  The silt forms a confining layer over coarser
sand and gravel deposits which lie at depths from 12 to 20 meters below
the surface.  The deep sand and gravel serves as the principal aquifer
for the wells of residents in the Twin Lakes area.  Soils developed on
the glacial materials are well drained and moderately permeable, except
in lowlands.  Erosion potential is low where the soils are protected
by vegetative cover.  Construction in the steep areas has caused
severe erosion and sedimentation.

    F.  Vegetation,  Open space in the watershed is comprised of small
upland areas of oak, beech, hickory, and sugar maple woods, low poorly
drained areas of elm, maple, and willow, and swampy areas with poison
sumac, swamp maple, alder and sparse tamarack.  No extensive open fields
or pasture land are in the basin, except for large lawns.

    G.  Population.  There are approximately 1510 people living within
the watershed in 430 houses.

    H.  Land Usage.  The watershed contains two types of land:  residential
and open space.  The major land use is single family residential.

    I.  Use of Water.  The water in the lakes is used solely for
recreation.

    J.  Sewage and Effluent Discharge.  Until 1972, sewage was dis-
charged into septic tanks and thence by groundwater and stream flow
to the lakes.  Sewage was diverted during late 1971 through 1972 to
a package plant which discharges away from the watershed.  All storm
drainage enters the lakes.  There is no industrial discharge.
                                  243

-------
i     o    s     ~    J,
1......L	L.-_L.  - 1  . . J	T__.  ._

-------
w
OJ
:=
CJ
Q
IX.
r
CO
a:
UJ
                                                                                                              V)
                                                                                                              UJ
                                                                                                              :*:
                                                                                                              z
                                                                                                              5
                                                          245

-------
III.   MORPHOMETRIC AND HYDROLOGIC  CHARACTERISTICS  OF  THE  TWIN LAKES

      The two lowermost lakes  of the  Twin Lakes  Watershed,  East  (ETL)
  and West (WTL)  Twin Lakes, are small  eutrophic kettle-type  lakes of
  similar morphology (Figure 2).  WTL is  slightly  larger  in area and
  volume and lower in mean depth,  due primarily  to the  construction  of
  a lagoon and canals on the west  and northwest  sides of  the  lake (Figure
  1).

      A.  Surface Area, Length,  Width.   See Table  1.

      B.  Volume  of Water and  Regulation.  Lake  volumes and volume-area
  relationships are given in Tables 1 and 2.  The lakes  receive water
  from precipitation, outflow  of small,  upland,  man-made  ponds,  storm
  flow,  small spring-fed woodland  streams,  and groundwater.  Water is
  lost by evaporation, and by  outflow from ETL.  Rate of  outflow is
  partially controlled by a small  marsh and golf course pond. WTL and
  Dollar Lake flow into ETL.

      C.  Maximum and Average  Depths.  See Table 1.

      D.  Exceptional Depths and Ratio  of Surface  Area  of Deep and
  Shallow Waters.See Table 1 for depths.Shallow waters are considered
  to  be  the zone  of macrophyte growth.   Using areas of  Table  2 and areas
  of  macrophytes  (see Section  IV,  C.  7),  the ratio of deep to shallow
  waters of WTL and ETL are 3.96 and  2.49 respectively.
                Table 2.   Volumes  and Areas  of Lake Strata
  Depth or
  Top of
  Stratum

     0
     1
     2
     3
     4
     5
     6
     7
     8
     9
    10
    11

  Total
Volume (m )

  319,250
  247,333
  223,659
  202,391
  175,592
  141,592
   94,406
   49,886
   25,824
   13,627
    5,459
      203

1,499,222m3
Area (m )

 340,152
 276,112
 234,702
 213,700
 191,290
 160,350
 123,630
  67,940
  33,800
  18,600
   9,200
   2,440
Volume (m )

  252,911
  218,156
  188,917
  169,883
  151,315
  127,240
   98,825
   68,660
   38,331
   19,305
   10,217
    3,389

1,350,568m3
Area (m )

 268,820
 237,330
 199,530
 178,500
 161,410
 141,440
 113,550
  84,800
  53,700
  24,800
  14,290
   6,630
      E.   Ratio of Epi-  Over Hypolimnion.   The  principal  metalimnetic
  strata  were identified from temperature  data.   Table 3  catalogs this
  feature for all  observation days.   Table 11  shows  average extents,
  volumes,  and volume-ratios of the  epilimnion  and hypolimnion.   During
  1971-74,  the metalimnion has tended to occur  deeper in  each lake.
                                    246

-------
                               TABLE 3
Catalog of Observation Dates.  Thermal conditions indicated in parentheses:  Ice = ice
present;	= unstratified; Str or numbers = metalimnion present, with numbers
indicating depths (m) at which the bounds of the metaUmnion occurred.
                                  East Twin Lake


1971
Total Visits
35
Apr




May



Jun




Jul



Aug



Sep

Oct



days
5 (---)
9 (---)
14 (---)
17 (2,3)
21 (1,4)
5 (7,8)
12 (1,4)
19 (2,5)
28 (Str)
4 (Str)
8 (1,7)
18 (Str)
23 (2,7)
29 (2,6)
7 (2,7)
13 (2,7)
20 (3,8)
27 (3,7)
3 (3,7)
10 (3,7)
17 (3,7)
24 (3,8)
2 (3,8)
8 (2,8)
1 (2,8)
11 (5,8)
14 (6,9)
21 (6,9)
Oct 28
Nov 5
11
15
18
26
Dec 7

1972
(6,9)
(8,10)
(---)
(---)
(---)
(...)
(---)


Total Visits
47 days
Jan 31
Feb 10
17
24
Mar 2
9
24
28
Apr 4
11
18
25
May 2
9
16
23
30
Jun 6
13
20
(Ice)
(Ice)
(Ice)
(Ice)
(Ice)
(Ice)
(...)
(...)
(...)
(...)
(2,6)
(5,7)
(1,8)
(3,8)
(2,8)
(2,8)
(2,9)
(3,9)
(2,8)
(1,8)
Jun 27
Jul 5
11
18
25
Aug 1
8
15
22
29
Sep 5
12
19
26
Oct 3
10
17
24
31
Nov 7
14
21
28
Dec 5
12
19
26




(1,9)
(2,9)
(1,8)
(1,8)
(2,7)
(3,7)
(3,7)
(2,7)
(2,7)
(2,8)
(3,8)
(4,8)
(4,9)
^,4,10)
(6,10)
(6,10)
(6,8)
(8,9)
(9,11)
(9,10)
( •-)
-(,..)
(...)
(...)
(Ice)
(Ice)
(Ice)





1973


Total Visits
43 days
Jan 2
16
Feb 13
20
27
Mar 6
13
20
27
Apr 3
10
17
24
May 1
8
15
29
Jim 5
12
19
26
Jul 3
10
17
24
31
Aug 7
14

(Ice)
(Ice)
(Ice)
(Ice)
(Ice)
(Ice)
(...)
(...)
(...)
(...)
(...)
(8,9)
(Str)
(2,8)
(2,9)
(5,9)
(3,9)
(2,8)
(2,7)
(2,8)
(2,9)
(2,9)
(3,8)
(Str)
(2,8)
(Str)
(3,8)
(3,8)
Aug 21
28
Sep 4
11
18
25
Oct 2
9
16
23
30
Nov 6
13
27
Dec 11

1974
(3,8)
(1,8)
(2,7)
(3,7)
(4,8)
(4,8)
(5,8)
(5,8)
(5,8)
(7,9)
(Str)
(Str)
(...)
(...)
(...)


Total Visits
47 days
Jan 7
28
Feb 11
27
Mar 6
18
Apr 1
9
16
24
30
May 7

(Ice)
(Ice)
(Ice)
(Ice)
(...)
(...)
(...)
(...)
(7,9)
(4,6)
(2,5)
(4,6)
May 17
24
31
Jun 7
14
20
26
Jul 2
11
18
25
30
Aug 6
13
20
27
Sep 3
10
17
24
Oct 1
8
15
22
29
Nov 5
12
19
26


(2,7)
(1,8)
(2,8)
(2,7)
(3,7)
(3,7)
(3,7)
(3,7)
(2,8)
(2,7)
(Str)
(3,8)
(3,8)
(3,8)
(Str)
(2,8)
(4,8)
(4,9)
(4,8)
(5,8)
(6,8)
(7,9)
(4,8)
(Str)
(9,10)
(Str)
(10,11)
(---)
(...)


                                 West Twin Lake

1971
Total Visits
24 days
Apr 20 (2,5)
28 (8,9)
May 15 (2,5)
Jun 8 (2,6)
22 (2,6)
28 (1,7)
Jul 6 (2,6)
12 (2,6)
19 (2,6)
26 (2,6)
Aug 2 (2,6)
9 (3,6)
16 (2,6)
23 (2,5)
Sep 1 (2,6)
7 (1,6)
29 (4,6)
Oct 12 (6,7)
19 (5,6)
26 (5,7)
Nov 4 (8,9)
11 (---)
18 (---)
26 (---)

1972
Total Visits
47 days
Jan 11 (Ice)
Feb 8 (Ice)
15 (Ice)
22 (Ice)
29 (Ice)
Mar 7 (Ice)
24 (---)
31 (---)
Apr 6 (---)
13 (4,5)
20 (4,6)
27 (5,8)
May 4 (2,7)
11 (Str)
18 (3,7)
25 (0,8)
Jun 1 (3,8)
8 (4,7)
15 (3,9)
22 (3,7)
29'(3,7)
Jul 6 (4,8)
13 (2,9)
20 (2,7)
27 (1,8)
Aug 3 (4,8)
Aug 10 (4,8)
17 (3,7)
24 (3,9)
31 (2,7)
Sep 7 (4,9)
14 (3,9)
21 (4,7)
28 (5,8)
Oct 5 (5,8)
12 (6,9)
19 (8,10)
2k (---)
Nov 2 (---)
9 (---)
16 (---)
22 (---)
30 (---)
Dec 7 ( 	 )
14 (Ice)
21 (Ice)
29 (Ice)
1973
Total Visits
45 days
Jan 4 (Ice)
11 (Ice)
18 (Ice)
Feb 15 (Ice)
Feb 22 (Ice)
Mar 1 (Ice)
8 (Ice)
15 (---)
22 (---)
29 (---)
Apr 5 (---)
12 (---)
19 (5,6)
26 (2,6)
May 3 (5,8)
10 (5,8)
17 (7,8)
24 (6,7)
31 (4,9)
Jun 7 (4,8)
14 (3,8)
21 (3,8)
28 (3,9)
Jul 5 (2,9)
12 (3,8)
19 (2,7)
26 (3,8)
Aug 2 (3,8)
9 (3,8)
16 (3,7)
23 (4,7)
30 (1,9)
Sep 6 (2,7)
Sep 13 (4,7)
20 (5,9)
27 (5,8)
Oct 4 (5,9)
11 (5,8)
18 (8,9)
25 (9,10)
Nov 1 (---)
8 (---)
15 (---)
27 (---)
Dec 11 (---)
1974
Total Visits
40 days
Jan 7 (Ice)
28 (Ice)
Feb 11 (Ice)
27 (Ice)
Mar 6 (---)
18 (---)
Apr 1 (---)
12 (---)
19 (3,4)
27 (Str)
May 3 (3,6)
14 (4,7)
21 (2,7)
May28 (3,7)
Jin 4 (2,7)
11 (3,6)
18 (4,7)
25 (3,7)
Jul 1 (4,7)
9 (1,7)
18 (2,7)
25 (3,8)
30 (3,6)
Aug 6 (3,7)
13 (3,8)
20 (Str)
27 (2,7)
Sep 5 (4,7)
12 (2,7)
19 (4,7)
26 (5,7)
Oct 3 (7.10)
10 (8,9)
17 (Str)
24 (---)
31 (---)
Nov 7 (---)
14 (---)
21 (---)
27 (---)
                                         247

-------
    F.  Duration of Stratification.  Both lakes are dimictic second
class lakes.For purposes of discussion an annual cycle of four
stadia is defined:  WINTER (ice present), SPRING (unstratified,
SUMMER (metalimnion present), and FALL (unstratified).   Table 3
catalogs the occurrence of these conditions for all days the lakes
were visited.  For convenience in this report, the start of winter
has been defined as January 1.
    Ice usually appears in December and disappears in early March.
The lakes commonly thaw and refreeze at least once during this interval.
Ice thickness is usually 7-10 cm.; thickness of 30 cm.+ has been
reported.
     The 1971-74 average onset of summer was April 14 for both lakes.
The 1971-74 average summer lasted 211 days in ETL (to November 11) and
196 days in WTL (to October 27).  During 1971-1974, summer conditions
have lengthened in ETL from 207 to 217 days and have shortened in WTL
from 206 to 188 days.

    G.  Nature of Lake Sediments.  Sediment characteristics of the
surficial (upper 2 cm.) muds of the littoral, metalimnion (sublittoral)
and hypolimnion (profundal) were determined in 1972-73  by Lardis  (1973)
(Table 4).   Littoral sediments contain mainly decaying vegetation,
shell fragments, and allochthonous debris.  Sublittoral muds are brown
to black-gray with lesser and varying amounts of decaying vegetation.
Profundal zone muds are dark gray-black in ETL, brownish-black in WTL,
and are much blacker during anoxic periods; rusty-brown above a gray-
black layer during oxygenated periods.  Profundal sediments throughout
the year are very fluid and easily disturbed.  Both lakes exhibit an
increased amount of organic phosphorus (method of Mehta et al. 1954)
with depth of overlying water.  Mean phosphorus content of ETL sediment
is significantly less than WTL  (0.66 mg.P/g. vs. 0.85 mg.P/g«), even-
though loading to ETL indicates ETL to be more enriched.  Lardis attributec
this to the organic phosphorus added to WTL during the dredging of
the canals in 1969.
    The mean phosphorus content of the littoral zones are similar and
vary little from season to season.  The sublittoral of WTL has con-
siderably more phosphorus than ETL and exhibits a decline from fall to
winter.  The greatest difference between lakes is in profundal samples.
In both lakes, the phosphorus content of profundal surficial muds in-
creases from fall to spring, then declines after onset of summer anoxic
conditions  (13% mean decrease in WTL, from spring levels), suggesting
that the increase in dissolved ortho phosphate in hypolimnetic waters
may in part be from this decrease in sediment-interstitial water phos-
phorus .
    The organic content of ETL and WTL surficial sediments increases
with depth of sample; WTL profundal samples have more organic matter
than ETL.  The percent organic content of dry sediment samples ranges
from 14% in littoral to 39% in profundal in ETL, 14% in littoral to
41% in profundal in WTL.  The water content of surficial sediments
ranged from 71.5 to 97%; highest values were found in profundal samples.
Most samples were 94-96% water.
                                248

-------
Table 4.  Means of Total Organic and Dissolved  Inorganic Phosphorus  in
          the Sediments of Each Limnetic Zone  (+25 x; n = number  of
          samples; P04-P in mg.P/g. dry sediment) from Lardis  (1973).
                            West Twin Lake
Littoral
Sublittoral
Profundal
Littoral
Sublittoral
Profundal
   Fall
 .54^.08
 .89+_.03
1.19+.08
 n
19
 9
21
Winter
.54+. 09
.78+. 05
1.26+.13
n
8
8
9
Spring
.53+. 09
.79+. 05
1.27+.11
 .43+_.07  19
 .65+..06   9
 .80+.03  20
                                                 n
      East Twin Lake
     .53+_.13  9   .52+_.10  9
     .65+.05  7   .67±.06  8
     .83+.06  9   .87+.07  9
  Summer
 .57+..12
 .77+..06
1.04+.03
n
7
 . 53+_. 08  9
 .67^.06  7
 .77+.04  9
    H.  Seasonal Variation of Preciptation and Evaporation

Table 5.  Precipitation and Evaporation.  Twin Lakes Watershed.


Mo.
J
F
M
A
M
J
J
A
S
0
N
D
Total
Mean

Precip.
Cm)
.0356
.0511
.1001
.1628
.0955
.1018
.0823
.0612
.2070
.0386
.0996
.0886
1.1242
0.0937
1972
Volume
(m3)
118904
170674
334334
543752
318970
340012
274882
204408
691380
128924
332664
295924
3754828
312902

Evapo.
Cm)


.0527
.0606
.0970
.1356
.1577
.1516
.1233
.0880


0.8665
0,1083
1973
Precip.
(m)
.0417
.0483
.0623
.0875
.1270
.1028
.0655
.0726
.0708
.1143
.0657
.0617
0.9202
0,0767
Volume
(m3)
139278
161322
208082
292250
424180
343352
218770
242484
236472
381762
219438
206078
3073478
256123
Evapo.
(m)


.0247
.0529
.0896
.0929
.1074
.1119
.1180
.1000


0.6974
0.0872
1974
Precip.
(m)
.0907
.0706
.1044
.1270
.1155
.0767
.0723
.1750
.0558
.0695
.1270
.0589
1.1434
0.0953
Volume
(m3)
302938
235804
348696
424180
385770
256178
241482
584500
186372
232130
424180
196726
3818956
318246
Evapo.
Cm)


.0660
.0889
.1092
.1499
.1727
.1372
.0805
.0559


0.8603
0.1075
Area of watershed = 334 hectares.  Volume to lakes obtained by multiplying
lake area (m^) by precipitation  (m).

    I.  Inflow-Outflow of Water
Table 6.  Water Inflow-Outflow (m3x!03)

A.  West Twin Lake                  1972
     surface streams               145.45
     groundwater                   307.37
     precipitation on lake         382.35
     runoff                        382.96
     total inflow                 1218.12
     evaporation                   343.61
     outflow (to ETL)              916.84
B.  East Twin Lake
     surface streams              1057.31
     groundwater                   246.02
     precipitation on lake         251.36
     runoff                        379.66
     total inflow                 1934,34
     evaporation                   268.70
     outflow (out of watershed    1700.01
                                        1973
                                       1F9779
                                       321.33
                                       313.01
                                       362.56
                                      1177.68
                                       273.53
                                       826.24

                                       956.12
                                       247.02
                                       246.61

                                      iffi'.ft

                                      1444!$2
                                              1974
                                             3T2T45
                                             307.33
                                             401.96
                                             598.60
                                            1640.33
                                             270.33
                                            1461.58

                                            1479.02
                                             246.02
                                             317.66
                                             416.23
                                            2458.93
                                             223.68
                                            2307.49
                                    249

-------
     J.   Water Currents,   No investigations  of water currents in the
 Twin Lakes have been made.

     K.   Water Renewal Time.  Water renewal  times (years)  are listed in
 Table 1.

IV.   LIMNOLOGICAL CHARACTERIZATION SUMMARY

     Methods

     1.   Limnological Methods.  Unless otherwise noted,  all limnological
 observations were made from a water column  over the deepest point in
 each lake at depths 0.1,  2, 4,  7, and 10 meters.  Table 3 catalogs all
 days on which the lakes were visited.  Visits were generally weekly from
 late spring through early fall, but less frequently otherwise.   The list
 of  features monitored was complete for most but not all visits.  An
 annotated list of quantitative methods is given below:

     a.   Physical
          (1) temperature—at one-meter intervals;  Whitney resistance
              thermometer.
          (2) transparency--20 cm. diameter, alternating black-white
              quadrants,  Secchi Disc.
          (3) light—Whitney LMD-8A photometer with sea  and deck cells.
          (4) conductance—in the laboratory;  YSI Model  31 conductivity
              bridge.
     b.   Chemical
          (1) pH--in laboratory; Corning Mod.el 7 meter and combination
              electrode.
          (2) alkalinity — titration with 0.02N H2S04; endpoint pH 4.5.
          (3) dissolved oxygen—at one-meter intervals;  titration with
              0.0125N sodium thiosulfate, azide modification.
          (4) sulfate—turbidmetric, using Hach Chemical Co. reagents;
              standard curve prepared in our laboratory.
          (5) nitrate--cadmium reduction using Hach Chemical Co. reagents;
              standard curve prepared in our laboratory.
          (6) ammonia--direct nesslerization,  using Hach Chemical Co.
              reagents; standard curve prepared in our laboratory.
          (7) ortho PC>4-P —at one meter intervals;  ascorbic acid-ammonium
              molybdate,  on 0.45ju Millipore filtered samples.
          (8) total P04~P  unfiltered—at one-meter intervals; persulfate-
              sulfuric acid digestion.  P04~p determined as in  (7).
          (9) total P04-P  filtered—persulfate-sulfuric  acid digestion of
              0.45 /a filtered samples.  PO.-P determined as in  (7).
     c.   Biological
          (1) phytoplankton--2S ml. samples  filtered on  0.45 /i Millipore
              filters, dried, cleared with immersion oil,  counted at 140 x,
              11 Whipple fields; of dominant species, using appropriate
              geometric shapes to calculate  cell volume  (McNabb, 1960.
              Limnol. Oceanogr. 5:57).
          (2) Chlorophyll  A--500 ml. sample  filtered through GF/A filter,
              extracted with 901 buffered acetone,  using tissue grinder;
              equations (trichromatic) of Parsons and Strickland, no acid
              correction  (Long and Cooke, 1971. Limnol.  Oceanogr. 16:990).
                                  250

-------
         (3) zooplankton—vertical tow, #20 rjet, lake bottom to top of
            hypolimnion  (or 6 m. when unstratified) and bottom of
            metalimnion  to surface  (6 m. to surface when unstratifled),
            using rim line and weighted bucket to close net.  10 ml.
            aliquots counted in duplicates.
         (4) macrophytes--outer limit of plant distribution from shore
            measured at  several points around lake perimeter.  Percent
            cover estimated, and plant samples obtained by use of SCUBA.
            Dry weight per area multiplied by percent cover and area of
            macrophyte community.  Net yield estimated by difference.
         (5) potential plankton metabolism—plankton samples were incubated
            in the laboratory at 5000 lux.  Metabolism was measured by
            the pH method in light and dark bottles after 4 hours of
            incubation.

    2.  Surface Water Measuring Methods.

Twin Lakes Stream
Station
   1
   2
   3
   4
   5
   6
                        Measuring Method
             90° V notch weir and stilling well
             90° V notch weir and stilling well
             3'H flume, Agriculture Research Service
              design
             15" Culvert discharge, current meter
             24" Culvert discharge, current meter
             Stage-Discharge Rating Curve, stilling
              well
             2 submerged culverts 15" diameter,
              current meter
   8
   9
             Culvert, bucket
             90° V notch weir, bucket
Dollar Lake
Stream Station
             Culvert discharge, bucket
   1
   2
   3
   4
   5
             Culvert discharge, bucket
             60° V notch weir and stilling basin
             Culvert discharge, bucket
             90° V notch weir, and stilling well
Frequency of Measure
Continuous recorder
Continuous recorder
Continuous recorder

Daily
Daily
Continuous

Daily

Daily
Daily
Daily
Daily
Daily
Daily
Daily
    3.  Surface Run-off.  Land runoff or storm flows were computed from
lake level increases,as recorded by limnographs, in excess of that from
direct precipitation and stream inflows.

    4.  Ground Water Methods.  Twenty-eight shallow wells were installed
around the perimeter of the lakes and a flow net was constructed.  Specific
discharge was determined from the hydraulic gradient and field measurement
of permeability.  Average cross-sectional discharge depth between these
wells was assumed to be 3.0 meters (range 1-6 meters).  Wells were sampled
monthly for water chemistry.  A deep piezometer nest beside WTL was used
to estimate the upward hydraulic gradient and discharge into the lakes of
deep ground water.  Ground water inflow and loading is the sum of shallow
and deep groundwater discharge.
                                  251

-------
    5.  Precipitation-Evaporation.  Precipitation was measured with a
recording Leupold-Stevens type Q 6 weighing bucket, located at WTL.
Rain and snow samples were collected at the University (8 km. south of
watershed) for chemical analysis.  These samples included dry fallout.
Evaporation was measured in 1972 from daily temperature data, using
the Blaney-Criddle equation, and in 1973-74 with a U.S. Weather Bureau
Class A Evaporating Pan and a Weather Measure Recording Evaporimeter.

    Results.  Averaged data are displayed in tabular form as indicated in
the annotated list below.  Wherever appropriate in averaging, values for
limnological features were weighted with respect to time in days.  Where
appropriate, both unweighted (COL) and volume-weighted (LAKE) values
were averaged.  For features expressed as concentrations, average total
amounts in the lake may be found by multiplying the LAKE averages by the
total lake volumes (Table 1).  The surface densities of these average
total amounts may be found by further dividing by total lake areas
(Table 1).

    A.  Physical

        1.  Temperature.  Tables 7 and 8.

        2.  Conductance.  Tables 9 and 10.

        3.  Light.  Secchi disc transparency is summarized in Table 12.
Depths of light extinction at 10%, 1% and 0.1! of surface light intensity
are presented in Table 13 for selected dates in 1971 and 1972.

        4-  Color.  No measurements of color have been made.

        5.  Solar Radiation.  No measurements of incident solar radiation
have been made.

    B.  Chemical.

        1.  pH.  Tables 14 and 15.

        2.  Dissolved 0xygen.  Tables 16 and 17.

        3.  Phosphorus.  Total phosphorus concentrations are summarized
in Tables 18 and 19.Filterable total "soluble" phosphorus concentrations
are summarized in Tables 20 and 21.  Filterable ortho phosphorus
concentrations are summarized in Tables 22 and 23.

        4.  Nitrogen.  "Total" nitrogen (ammonium and nitrate nitrogen
only) concentrations are summarized in Tables 24 and 25.  The two fractions
recorded are summarized in Tables 26, 27, 28, and 29.

        5.  Alkalinity.  Tables 30 and 31.

        6.  Electrolytes.  Sulfate concentrations only are summarized in
Tables 32 § 33.

        7.  Trace Metals.  No measurements of trace metal concentrations
were made.
                                  25 Z

-------
     Table   7.   TEI1P  COL:   Average  Temperatures  in the Column (°C) .
West
Year
1971
1972
1973
1974
East
1972
1973
1974
West
1971
1972
1973
1974
East
1971
1972
1973
1974
Twin
Lake
Winter
Season
2
2
3
Twin
2
2
3
Table
Twin
2
2
3
Twin
1
1
3
.296
.346
.179
Lake
.163
.011
.208
8.
Lake
.161
.312
.116
Lake
.930
.992
.189
Spring
Season
3.
6.
6.
6.
3.
5.
6.
TEMP
3.
6.
6.
7.
3.
5.
5.
776
469
209
845
538
049
075
LAKE:
782
661
333
232
729
322
895
Summer
Season
14.146
13.405
15.643
13.853
13.737
12.559
14.539
12.732
Average
17.125
17.200
18.707
17,041
17.083
15.952
17.679
15.618
Epilim
Only
Hypolim
Only
20.533 10.
18.831 8.
20.506 11.
19.446 9.
20.945 8.
19.156 7.
20.496 9.
18.241 8.
Temperatures
20.554 10.
18.844 8.
20.501 11.
19.462 9.
20.972 9.
19.171 7.
20.504 9,
18.271 8.
713
240
095
766
930
027
552
001
in
853
389
289
943
065
147
663
119
Fall
Season
6.737
5.155
7.377
7.488
4.234
3.848
6.875
6.055
the Lake i
6.784
5.150
7.440
7.550
4.262
3.788
6.950
6.154
All
Seasons
12
8
10
10
11
8
10
9
15
10
12
11
13
10
11
11
.902
.657
.743
.042
.347
.649
.011
.740
.388
.586
.398
.773
.833
.604
.770
.520
   Table  9.   COND  COL:

West  Twin  Lake
T97I       =
1972
1973   428.02
1974
East  Twin  Lake
HTfl       -
1972
1973   429.29
1974
                        Average Conductances (20°C) in the Column (jamho)
                430.52
                420.95
                400.76
                399.72
         415.68
         412.47
         413.31
         375.47
         381.54
         398.61
         376.85
         391.00
         378.80
         357.69
         362.45
         373.29
435.07
430.49
449.44
384.72
413.14
417.63
400.81
-
400,75
373.34
-
376.21
412.39
417.89
414.12
375.12
393.59
397.10
  Table  1°.   COND  LAKE: Average Conductances  (20°C)  in  the  Column
West Twin  Lake
       428.19
     Twin Lake
 1972
 1973
'1974
 East
TSI
1972
1973
1974
        420.53
426.54
420.95
393.54
400.24
403.01   377.09    434.40   390.45    400.23
400.08   390.97    428.77       _      409.22
390.37   378.10    466.45   403.18    403.23
363.78   357.36    384.38   373.56    365.36
367.94   363.23    409.29       .      381.74
382.58   372.83    415.45   378.05    388.46
                                  253

-------
    Table  11.  Average Dimensions of Epilimnion and Hypoliranion.

                 A.  Lowest Extents of Epilimnion (m)•

                    1971      1972      1973      1974
                                   All
                B
West Twin Lake
East Twin Lake
West Twin Lake
East Twin Lake
West Twin Lake
East Twin Lake
West Twin Lake
East Twin Lake
West Twin Lake
East Twin Lake
   Table  12.  SECCHI TRANSPARENCY:

West Twin Lake
3.114 3.375 4.179 3.604
2.944 3.367 3.600 4.044
Highest Extents of Hypolimnion (m) .
6,243 7«821 7.964 7.114
7.167 8.369 8.250 7.906
C. Volumes of Epilimnion (m3) .
715866 796415 937229 829430
609036 665854 725323 770224
D. Volumes of Hypolimnion (m*) .
186099 68646 58244 108873
158646 72691 64412 97291
Ratios of Volumes, Epilimnion/Hypolimnion
3,847 11.602 16.091 7.618
3.839 9.160 11.261 7.917
3.562
3.496
7.275
7.926
818380
693600
106405
98001
a
7.691
7.077
           Average Secchi Disc Depths (m)
Year
1971
1972
1973
1974
East
1971
1972
1973
1974
Winter
2.728
2.519
1.593
Twin Lake
1.384
1.858
1.886
Spring
1.050
1.181
1.432
1.043
1.590
1.535
Summer
1.622
1.437
2.948
2.177
2.261
1.655
2.402
1.903
Fall
2.031
4.034
3.282
3.883
1.701
2.188
2.988
1.962
All
1 .707
2.170
2.754
2.323
2.146
1.623
2.304
1.866
             Table 13 .   LIGHT EXTINCTION
           Depths at  Intensities  .100,  .010  and  .001  of  Surface.
 Light  Intensity
     .100
     .010
     .001
West Twin Lake
East Twin Lake
1971
1.4679
3.5357
4.9536
1972
2.4286
5.3571
6.7833
1971
2.0250
4.6393
5.6857
1972
1.7600
3.6800
5.1600
                                 254

-------
       Table 14.  pH COL:  Average pH Values in the Column.



West Twin Lake
Winter Spring
Year Season Season
1971
1972
1973
1974 8.0271 8.4577
East Twin Lake
Summer Epilim Hypolim
Season Only Only
Fall All
Season Seasons
7.4575 7.7643 7.3466 7.6872
7.4127 7.8504 7.2345 7.2826
1971 -
1972 -
1973 - - 7.3699 8.0661 7.2452 6.8887
1974 ''.0596 8.2168 7.3405 7.7181 7.1212 7.4599
Table 15. pH LAKE: Average pH Values in the Lake.
West Twin Lake
1971
1972
1974 8.0449 8.4584
East Twin Lake
1971
1972
1973
1974 8.0074 8.2128
Table 16
Average
West Twin Lake
1971
1972 11670.7 14396.2
1973 10522.9 10932.5
1974 12770.6 12153.7
East Twin Lake
7.6143 7.7824 7.3455 7.6890
7.6337 7.8672 7.2464 7.2674
7.5462 8.0850 7.2416 6.8445
7.5601 7.7505 7.1344 7.4586
[02-OXY] COL: Dissolved Oxygen Gas,
Concentrations in the Column (jig O^)..
3363.9 9234.8 544.0 5005,8
3702.5 7776.7 950.2 8483.0
3952.3 8247.5 454.7 8739.4
3864.8 8318.2 466.4 6991.4
1971 - 12983.3 3733.1 9045.1 614.2 8347.8
1972 8970.3 12143.0 3582.9 8782.8 530.9 8057.1
1973 9859.0 10674.6 4357.0 8622.2 722.6 9056.6
1974 11318.1 11735.9 4191.1 8096.5 569.9 8150.9
Table 17. [02-OXY] LAKE: Dissolved Oxygen Gas,
Average Concentrations in the Lake (jig 02/1) „
West Twin Lake
1971
1972 13265.3 14250.1
1973 12018.9 11079.3
1974 13262.9 12245.5
East Twin Lake
1971 - 13920.8
1972 11792.9 12596.2
1973 11563.9 11029.9
1974 12457.3 11986.7
5840.3 9287.6 566.9 5592.7
6070.5 7853.0 1016.1 8476.0
6579.9 8309.8 509.5 8676.6
6554.7 8405.7 621.6 7479.7
6135.2 9124.9 717.7 8598.6
5865.9 8827.7 588.7 8657.4
6752.5 8650.6 733.8 9038.5
6551.3 8226.9 669.4 8299.4
7.4955
7.5018
7.2460
7.4699
7.6285
7.6299
7.3271
7.6464
3617.3
7184.1
6735.2
6910.3
5029.5
5925. 1
6705.0
6631.8
5802.1
8766.1
8419.6
8533.6
6909.8
7930.5
8403.0
8330.7
                                  255

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         Table 18.  [TOT-P] COL:  Unfiltered Total Phosphorus,
            Average Concentrations in the Column  (ug P/l).
West Twin Lake
Year
1971
1972
1973
1974
East
1971
1972
1973
1974
Winter
Season
152
125
122
Twin
100
112
97
.79
.17
.31
Lake
.68
,54
,41
Spring
Season
170,82
85,12
78.04
96.42
77.53
65.60
Summer
Season
417
257
277
229
289
181
187
189
.76
,09
.26
,90
.24
o26
.98
.06
Epilim
Only
37.63
57.21
53.02
48.35
29.76
43.95
38.07
45.30
Hypolim
Only
779
494
616
512
687
377
430
466
.76
.35
.97
.02
.23
.55
.73
.55
Fall
Season
122.
132.
135.
125.
66.
97.
72.
94.
86
20
52
79
81
45
27
11
All
Seasons
343.04
204.85
206.28
173.67
226.56
145.96
147.77
148.79
         Table  19.   [TOT-P] LAKE:  Unfiltered Total Phosphorus,
             Average Concentrations in the Lake  (ug P/l).
West
1971
1972
1973
1974
East
1971
1972
1973
1974

Twin Lake
-

-
134.84 171.55
111.02
136 72
Twin Lake
-
81.27
95.44
81.23
Table 20 .
90,46
79.78

-
98.18
75.74
66.88
[TOT-P

161.
108,
99.
78.

104.
79.
74.
73.

44
63
78
66

39
48
28
52
D1SS] COL:
Average Concentrations
West
1971
1972
1973
1974
East
1971
1972
1973
1974

Twin Lake
-
-
98.18
84.13
Twin Lake
-
.
79.59
46.63
Table 21 .

-
-
43.32
26.73

-
_
26.05
18.69
[TOT-P

-
-
236.
210.

-
_
195.
160.
DISS



75
88



21
05
] LAKE

35.
55.
52.
47.

28.
43.
37.
44.

94
55
44
17

94
27
58
46

756.
483.
598.
483.

671.
362.
416.
447.
Filterable
in

-
-
44.
31.

-
.
69.
27.
the



02
88



85
04

21
66
30
40

17
22
93
11
Total
Column (ug

-
-
520.
492.

-
_
414.
438.
: Filterable
Average Concentrations in the
"West
1971
1972
1973
1974
East
1971
1972
1973
1974
Twin Lake
-
-
80.82
84.03
Twin Lake
-
-
61.27
30.32

-
-
43.82
28.14

-
.
25.42
19,82

-
-
88.
65.

-
_



57
34



100.03
49.
56

-
_
40.
28.

-
.
68,
24.



58
81



.70
74
Lake

-
_
494.
434.

-
^
391.
399.



30
15



34
62

122.86
127.53
133.87
121,08

66,78
95.66
76.41
93.83

151
122
106
96

93
83
78
76

.67
.17
.49
.83

.79
.70
.61
.12
Phosphorus ,
P/l).

-
-
95 .79
112.12

-
_
105.43
48.09


-
-
168
147

-
_
145
112




.70
.97



.08
.04
Total Phosphorus ,
(Jig



71
21



48
16
P/l).

-
•
99.27
100.98

-
_
102.71
46.58


.
_
84
70

-
_
85
42




.40
.26



.43
.25
                                  256

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       Table 22 .   [P04-P DISS] COL:  Filterable Ortho-Phosphate
      Phosphorus, Average Concentrations in the Column  (jjg  P/l) .
West
Year
1971
1972
1973
1974
East
1971
1972
1973
1974
Twin Lake
Winter
Season
106.66
75.56
57.78
Tt^in Lake
23.91
54.05
31.95
Spring
Season
14.64
22.83
6.53
21.45
14.40
4.99
Summer
Season
207.12
181.69
219.32
178.85
142.62
129.27
147.30
139.85
Epilim
Only
18.26
11.02
16.42
12.01
17.40
9.69
8.20
9.52
Hypolim
Only
256.00
405.53
516.28
451.15
326.36
329.86
381.35
404.12
Fall
Season
84.16
98.07
84.52
48.70
35.04
26.24
All
Seasons
207.12
134.40
152.81
119.20
142.62
84.43
101.83
93.47
        Table 23.   [P04-P DISS] LAKE:  Filterable Ortho-Phosphate
        Phosphorus, Average Concentration in the Lake  (ug  P/l).
West Twin Lake
1971
1972 82.73
1973 56.63
1974 52.10
East Txvin Lake
1971
1972 8.25
1973 36.29
1974 13.82
14.
18.
6.
23.
11.
5.
10
92
32
59
46
09
69
51
58
35
52
36
39
31
.76
.58
.64
.44
.09
.12
.31
.55
13.
10.
15.
10.
17.
9.
7.
8.
32
82
75
02
33
59
71
54
392.
393.
507.
419.
310.
316.
371.
385.
12
39
92
48
74
84
01
34
82
96
78
48
33
25
.80
.93
.48
.20
.75
.58
69.76
62.69
60.47
42.20
52.09
29.73
35.08
24.62
           Table 24 •   [TOT-N] COL:  Total Nitrogen, Average
                Concentrations in-the Column  (mg N/1J.
West Twin Lake
T57I     :
1972
1973
1974
East
  0.4152
  0.9693

Twin Lake
1F7T
1972
1973
1974
  0.2332
  1.0470
0.2431
0.3599
0.1835
0.5944
3.9208
1.8772
2.0837
3.0609
1.5944
1.7621
0.4150
0.3788
0.3861
0.3131
3.8550
4.7491
3.2371
3.6645
           Table 25 .   [TOT-N] LAKE:
                 Concentrations
                                in
                                Total Nitrogen,.
                              the Lake (mg N/l)
1.2810
1.5051
1.2768
1.1608
                                     Average
West Twin Lake
3.9208
1.2471
1.5979
3.0609
1.0622
1.4239
1971
1972
1973
1974
East
1971
1972
1973
1974
0.
0.
Twin
0.
0.
4041
8834
Lake
1832
9542
0.2616
0.3187
0.1821
0.5647
1.9289
0.7854
0.7507
1.3446
0.7089
0.8065
0
0
0
0
.3987
.3528
.3602
.3206
3
4
3
3
.6490
.4626
.0889
.4919
1.
1.
1.
1.
3300
3716
2251
1118
1.9289
0.7291
0.8326
1.3446
0.582S
0.8395
                                  257

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         Table 26.  [NH4-N] COL:  Ammonium Nitrogen, Average
                Concentrations in the Column  (mg N/l).
West
Year
1971
1972
1973
1974
East
1971
1972
1973
1974
Twin
Lake
"Winter
Season

0.
Oc
1.
Twin
0,
0
0.
.
1364
7975
0024
Lake
1153
8422
8494
Spring
Season
—
0.0808
0.2440
0.3390
0.0734
0.4023
0.2751
Summer
Season
3.
1.
2,
2,
2.
1,
I.
1.
8199
8204
0288
1483
9723
5287
7011
6661
Epi lin
Only
0.
0.
0.
0.
0.
0.
0.
0.
4381
3816
3296
3184
3350
3429
2627
2971
Hypolim
Only
6.
3.
4.
4.
6.
3,
3.
4.
2037
7723
6866
4126
1336
1380
6008
7045
Fall
Season
.
1.1561
1,3330
0.5185
Iol605
0.9450
0.0776
All
Seasons
3.8199
1.1070
1.4960
1.4520
2.9723
0.9716
1.3090
1.2076
         Table 27 o   [NH4-N] LAKE:  Ammonium Nitrogen, Average
                 Concentrations  in the Lake (mg  N/l).
West Twin Lake
1571
1972
1973
1974
East
1971
1972
1973
1974
0.0995
0.7023
0.9996
Twin Lake
0.0652
0.7360
0.6193
0
0
0
0
0
0
.0951
.2191
.3129
.0731
.3668
,2883
1.
0,
0.
0.
1.
0.
0.
0.
8383
7440
7009
7647
2649
6594
7517
5082
0.4371
0.3654
0.3051
0.3178
0.3342
0.3175
0.2694
0.2978
5 ,
3,
4,
3.
^f 0
2,
3 „
4.
8251
5696
4019
8305
8155
9913
4298
1861
1.
1,
0.
1.
0.
0.
2061
2031
4882
1113
8886
0757
1.8383
0.5886
0.7337
0.6994
1.2649
0.5004
0. 7247
0.4589
           Table  28=   [N03-N] COL:  Nitrate Nitrogen,  Average
                Concentrations in the Column  (mg  N/l).
West Twin Lake
1971
1972
1973
1974
East
1971
1972
1973
1974
.27878
.17181
Twin Lake
.11789
.20480
.16230
,11592
.11016
.19212
.03363
.05676
.05490
.02953
.06567
.06095
.07084
.03340
.04922
.06117
.04318
.05043
.00089
.08273
.06246
.00000
.09910
.06369
.12494
.17208
.11631
.21583
.03363
.14008
.10192
.02953
.09064
.11489
           Table 29 .   [N03-N] LAKE:  Nitrate Nitrogen,  Average
                Concentrations in the Lake  (mg  N/l).
West Twin Lake
1971
1972
1973
197'4
East
1971
1972
1973
1974
.30458
.18106
Twin Lake
.11804
.21822
,16650
.09957
.10898
.19791
.05917
o04142
.04980
.04908
.04953
.05478
.07100
.03327
.04767
.06126
.04274
.05115
,00265
.07937
.06072
.00000
,,09759
,06206
.12391
.16846
.11383
.22323
.05917
.14045
.09887
.04908
.08211
.11478
                                  258

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Table 30 .   ALK COL:   Average Alkalinities
       in the Column (mg CaC03/l).
West
Year
1971
1972
1973
1974
East
1971
1972
1973
1974

West
1971
1972"
1973
1974
East
1971
1972
1973
1974
Twin
Lake
Winter
Season
-
-
120
Twin
,
-
115

Twin
_
-
119
Twin
:
-
114


.36
Lake


.79

Lake


.55
Lake


.26
Spring
Season
-
-
116.54
-
-
110.61
Table 31 .
in
-
-
116.98
-
-
110,87
Summer
Season
-
122
118
-
120
115
ALK
the
-
108
100
-
104
102

.29
.91

.04
.87
LAKE:
Column

.07
,16

.79
.06
Epilim Hypol
Only Only
-
102.38
92.32
-
95.80
95.69
-
149.
150.
-
144.
141.
im

17
33

83
31
Fall
Season
-
116
105
-
107
104

.76
.05

.65
.49
All
Seasons
-
121.16
116.54
-
118.02
114.14
Average Alkalinities
(mg CaC03/l).
-
102.30
91.99
-
95.41
95.36
-
146.
147.
-
142.
138.

70
24

40
80
-
116
104
-
105
104

.08
.53

.67
.43
-
109.70
106.29
-
104.94
105.42
  Table 32 .   [S04] COL:  Sulfate, Average
  Concentrations in the Column (mMoles/1).
West
1971
1972
1973
1974
East
1971
1972
1973
1974
Twin Lake
0.490
0.5?3
Twin Lake
0.444
0.470
0.294
0.416
0,533
0.227
0.387
0.4-50
           0.399
           0,362
           0.357
           0.315
           0,331
           0 327
0.446
0.433
0.423
0.390
0.398
0.359
0.320
0.252
0.278
0.232
0.221
0.260
0,374
0.433
0.357
0.262
0,388
0.284
  Table 33 ,   [S04] LAKE:  Sulfate,  Average
  Concentrations in the Lake (mMoles/1).
West
1971
1972
1973
1974
East
1971
1972
1973
1974
Twin
0.
0.
Tw in
0.
0.
Lake
480
526
Lake
440
470
0
0
0
0
0
0
.305
.416
.527
.232
.380
.450
           0,448
           0 417
           0.400
           0.362
           0.376
           0.353
0.446
0.434
0.424
0.391
0.399
0.360
0.324
0.263
0.290
0.237
0.229
0.269
0.376
0.434
0.374
0.260
0.383
0.278
0.375
0.405
0.408
0.290
0.366
0.363
0.507
0.433
0.436
0.322
0.390
0.378
                   259

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    C.  Biological

        1.  Phytoplankton

            a.  Chlorophyll.  Chlorophyll A concentrations are summarized
in Tables 34 and~T5^      "

            b.  Primary Production.  We have adopted polarographic and
titrimetric methods of measuring pliytoplankton potential productivity
rather than in. situ methods (Long, 1971).  Maximum potential productivity
in situ was estimated by correcting laboratory data for phytoplankton
(Tensity, day length, and epilimnetic temperature  (assuming a QIQ °f 2)
(Tailing, 1957, 1965).  In 1970, at the height of the bluegreen algal
bloom the maximum productivity In sjLtu was estimated to be 3400 mg.
C/m2/day for ETL.  In 1974 the potential productivity estimate of each
lake was lower than that found in 1970 (Table 36).
            The production of macrophytes was estimated in 1972 (Rogers,
1974) by the harvest method, using SCUBA.  The rate, from 15 April to
1 July was (mg.C/mz/day) 375 for ETL, 267 for WTL, or about 10% to 301
of the maximum rate of the plankton.  Reduced growth rates were
correlated with plankton blooms.  No measurements for 1974 are available;
we estimate that macrophyte production at least equalled the 1972 rate,
thus bringing it up to about 50% of the net community metabolism of the
lakes.
            Oxygen deficits have been used to estimate productivity.
The contributions of allochtonous and autochthonous production are not
easily separated, and, as pointed out by Edmondson (1966) sedimentation
during periods of blue-green blooms is not rapid.  In the Twin Lakes,
some of this production may leave the lakes because of the low residence
time.  The deficits have declined since diversion, particularly in ETL
which does not have the canals and the heavy import from that area of
the watershed (Table 37).

            c.  Algal Assays.   We have monitored acid and. alkaline phos-
phatase in limnetic waters of both lakes from 1972-74.  Aphanizomenon
flos-aquae appears to produce it adaptively, particularly in late summer,
and both cell volume and potential productivity increase following the
appearance of alkaline phosphatase (Heath and Cooke, 1974).  This alga
(the dominant species in each year) appears to be phosphorus-limited in
August.
            Levels of total PC^-P at spring circulation are high (Table
40) and the relationship to mean euphotic zone Chlorophyll A is not as
strong as most lakes reported in Dillon (1974), particularly in 1972-73.
In 1974, the summer chlorophyll was much more closely related to spring
phosphorus levels.
            We conclude that these lakes have been phosphorus-limited
primarily in late summer, as evidenced by the phosphatase studies.  They
appear to be moving towards more general phosphorus limitation as loading
declines.

            d.  Identification and Count.  See Table 38 and Figure 3.
                                  260

-------
          Table 34.  [CHLOR-A] COL:  Chlorophyll a, Average
               Concentrations in the Column  (mg Chl/m J.
West Twin Lake
       Winter   Spring
Year   Season   Season
                    Summer
                    Season
         Epilim
         Only
         Hypolim
         Only
         Fall
         Season
1971
1972
1973
1974
East
1971
1972
1973
1974
30.
14.
20,
Twin
15.
11.
19,
107
126
083
Lake
183
072
369
66
34
36
40
27
30
o324
.870
.916
.992
.372
.661
31.
67.
53.
42.
28 =
26,
25.
33,
280
838
641
741
986
364
988
000
28
21
12
21
10
23
16
19
.018
.849
.246
.651
.162
.500
.021
.076
37.
107,
97.
59.
37.
16,
21.
26.
436
Oil
310
256
201
044
747
969
11.462
8.165
7.967
19.649
15.083
23.567
         All
         Seasons

          31.280
          47.584
          36.619
          32.328

          28.986
          23.201
          22.017
          29.527
          Table 35.  [CHLOR-A] LAKE:  Chlorophyll a. Average
               Concentrations in the Lake (mg Chl/irH) .
West Twin Lake
T9~7T~
1972
1973
1974
E_as_t_
1971
1972
1973
1974
  53.903   68.742
  19.101   43.987
  28.250   40.030
Twin Lake
26.791
37.770
24.888
29.944
28.249
21.551
12.110
22.106
38.737
108.878
94.954
62.435
11.233
8.257
9.164
  20.719   41.840
  15.006   33.400
  24.199   31.443
20.712
28.555
23.011
28.869
10.191
23.521
16.010
19.429
40.111
17.222
24.507
31.556
20.208
14.958
21.530
26.791
39.971
22.939
27.655

20.712
26.120
21.636
27.757
Table  36.  Estimated Net Plankton Community Photosynthesis  (mg  C/m^/day)
Date
TT~June 1974
 4 July 1974
11 July 1974
20 July 1974
 2 Aug. 1974
 9 Aug. 1974
West






mean
Table' 37.
Twin Lake
1758.8
298.1
135el
439.8
387.5
433.8
STTSTT
Oxygen De
                                             East Twin Lake
                                              mean
Date
T5TF
1971
1972
1973
1974
               West Twin Lake
                   0.0525

                   0.0523
                   0.0558
                   0.0223
                         East Twin Lake
                             0.0400
                             0.0740
                             0.1150
                             0.0362
                             0.0300
                                   261

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                  Table 38.   Major Phytoplankton Species.
                                   1972
        West Twin Lake - O.lm.
Summer  Aphanizomenon flos-aquae*
        Sphaeroecystis Schroeteri
        Cvclotella sp.
        Melosira granulata
Fall    Aphanizomenon flos aquae*
        Sphaeroecystis Schroeteri
        Asterionella formosa
Winter  Asterionella formosa
Spring  Ast.firtonel la formosa*
        Aphanizomenon flos-aquae
        Miscellaneous greens

Summer  Aphanizomenori flos-aquae*
        Anabaena limnetica*
        Microcystis aeruginosa

Fall    Aphanizomenon flos-aquae
        Anabaena limnetica*
Winter  Asterionella formosa*
        Fragilaria crotonensis

Spring  Fragilaria crotonensis*
        Asterionella formosa

*=dominants
1974
       East Twin Lake - O.lm.
       Aphanizomenon tlos-aquae*
       Anabaena limnetica
Aphanizomenon flos-aquae*
Asterionella formosa

Aphanizomenon flos-aquae
Asterionella formosa*
Aphanizomenon flos-aquae
Fragilaria crotonensis

Aphanizomenon flos-aquae*
Anabaena limnetica*
Microcystis aeruginosa
Stephanodiscus niagarae
Aphanizomenon flos-aquae*

Stephanodiscus niagarae*
Aphanizomenon flos-aquae*
Asterionella formosa
Aphanizomenon flos-aquae*
Stephanodiscus niagarae
Fragilaria crotonensis
         Table 39.  Species of Microcrustacea Identified from the
                    East and West Twin Lakes, 1969-1970.
Leptodora kindtii  (Focke)**
Diaphanosoma leuchtenbergianum Fischer
Daphnia ambigua Scourfield
D_. galeata Sars Mendotae Birge
EL, retrocurva Forbes
D. pulex Leydig, Richard**
Simocephalus exspinosus  (Koch)**
S. _serrulata (Koch)**
Ceriodaphnia reticulata  (Jurine)

Bosmina longirostris  (0. F. Muller)

Camptocercus rectirostris  (Schodler)*
Leydigia quadrangularis  (Leydig)**
Alona guttata Sars
       A_. Costata Sars**
       A_. quadrangularis (0. F. Muller)**
       Pleuroxus procurvas Birge
       I\ denticulatus Birge*
       Chydorus sphaericus  (0. F. Muller)
       Diaptomus reighardi Marsh
       Orthocyclops modestus  (Herrick)
       Eucyclops speratus  (Lilljeborg)**
       Tropocyclops prasinus mexicanus
        Kuefer
       Cyclops bicuspidatus thomasi  S. A.
        Forbes
       Mesocyclops edax  (S. A. Forbes)
       Ergasilus chautauquaensis Fellows
        * = East Twin Only
      ** = West Twin Only
                                     262

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Ham
saain-oaDiv

-------
        2.  Zooplaukton.  Limnetic microcrustacea were sampled on 26
dates between May 1969-May 1970 by Heinz (1971).  The species are listed
in Table 38.  Epilimnetic density ranged from 85/liter in May to I/liter
in late summer.  The periods of greatest density were May and December
(WTL) or January (ETL), with a small bloom in August.  The dominant
species were Daphnia galeata, Bosmina longirostris? Cyclops bicuspidatus
thpmasi, and Mesocyclops ecTax.The species composition of ETL and
WTLstrongly resembled that of littoral communities, and the mean number of
species/sample in limnetic waters was 2-3 times that of other lakes,
indicating in both instances that the littoral had a strong influence
on the limnetic waters.  Species composition and abundance were most
alike at spring circulation when Cyclops dominated.  The lakes diverged
in summer:  WTL was dominated by D. galeata, Bosmina, and Diaptomus
reighardi, but ETL by just D. galeata.  Fall circulation was dominated
by Daphirra and Cyclops, and winter stagnation primarily by Cyclops in
both lakes.

        3.  Bottom Fauna.  Bottom fauna are rare, presumably due to the
long anoxic period.Macroinvertebrates of ETL, identified primarily to
genus, as available in Wilbur (1974).

        4.  Fish.  The fish are dominated by Centrarchidae, primarily
bluegill, black crappie, pumpkinseed, and largemouth bass.  Fish size
has declined in recent years.

        5.  Bacteria.  Fecal coliform bacteria in surface waters fell
from 200 colonies/100 ml. (swim beach on WTL was closed in 1970 and 1971)
before diversion to near 0 in surface waters to 10 colonies/100 ml. in
deep water in 1972 and 1973.  Total bacteria/100 ml. ranged from 600-44,000
in both lakes in 1972, with the highest counts in the metalimnion and
at bottom.  Surface inflows were highly contaminated with fecal coliforms
before diversion, particularly those flowing into WTL, where samples
contained 90,000 colonies/100 ml. or more (1971 and 1972).  In 1973,
counts dropped to 0-600.  Groundwater samples were not as contaminated
as surface drainage samples, except for wells located directly below
leach fields where colony counts/100 ml. ranged from 30-5000.

        6.  Bottom Flora.  No studies of bottom flora have been conducted.

        7.  Macrophytes.  This community ranks with at least equal
importance to algae as a nuisance.  The distribution and biomass was
surveyed in 1972, using SCUBA (Rogers, 1974).  The species are:
Ceratophyllum demersum L., Najas guadulapensis (Spreng) Magnus, Elpdea
canadensis Michx.,  Nuphar acTvenum (Ait) Ait., Potamogeton crispus L.,
and Chara vulgaris L (Chlorophyta).  Macrophytes covered about 28% of
the lake area in ETL and 23% in WTL.  P. crispus was dominant in early
summer, N. guadulapensis (Etl) and C. demersum (WTL) during the rest
of the season.Total dry weight in ETL declined from 200 kg. (July)
to 100 kg. (September); in WTL it declined from 80 kg. (July) to 50 kg.
(August).  The total P04.-P content in ETL was about 2.5 kg., in WTL
about 1.5 kg. Nuphar contained about 6 kg.  PO.-P.
                                 264

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IV.   NUTRIENT BUDGETS SUMMARY

      A.    Phosphorus

        1.  West Twin Lake                    kg./year
                source
           Waste Discharges
           Land Runoff
           Precipitation
           Ground Water
           Surface Streams
           Total Inflow
           Total Outflow          106.16         79.25        131.69*

       2-  East Twin Lake
           Waste Discharges        0.00          O.UO          0.00
           Land Runoff            66.12         34.53         24.97
           Precipitation            6.20          5.24          7.17
           Ground Water            5.31         17.25         19.60
           Surface Streams       114.05         81.52        132.86
           Total Inflow           191.00        138.22        184.62
           Total Outilow          123.40        132.80        144.47
          #Apparently due  in part to sewer pipe leak in outflow of WTL (inflow of ETL)

      B.    Nitrogen  (Total Combined Inorganic) kg. /year.

       1.  West Twin Lake        1972          1973
           Waste Discharges         0.0           0.0
           Land Runoff           2067.5        1957.5
           Precipitation          1146.5         937.6
           Ground Water          1301.9        1439.1
           Surface Streams        937.4         763.9
           Total Inflow           5453.3        5098.1
           Total Outflow          3845.6        2048.6

       2.  East Twin Lake
           Waste Discharges         0.0           0.0
           Land Runoff           2714.2        1797.3
           Precipitation           897.5         737.0
           Ground Water           979.0         963.0
           Surface Streams       3845.0        1688.2
           Total Inflow            8435.7        5185.5
           Total Outflow          6408.6        4371.4

                                       265

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VI.  DISCUSSION

     East and West Twin Lakes are early eutrophic and mesotrophic.
 respectively, with the trend in both (except ETL in 1974 after the
 sewer leak) towards mesotrophy after sewage diversion.  Evidence for
 this is based primarily upon changing characteristics of the plankton.
 If macrophytes are included, the lakes are eutrophic.  Briefly the
 basis for this is:

     1.  The oxygen deficits are lower than often found in eutrophic
         lakes (Table 37).
     2.  While Aphanizomenon flos-aquae now dominantes the plankton, an
         increasing fraction of the community is diatoms.  Mean cell
         volume (from Figure 3) for 1972-74 for WTL ranged from 1.05-
         5.86; for ETL 3.44-6. 59/il./I.  Vollenweider  (1968) suggests
         that 3r5/il./l. might be the borderline between mesotrophy and
         eutrophy.  Mean summer photic zone chlorophyll A (Table 34) is
         on the low end of Sakamoto's (1966) range of 5-140 mg. ChlA/nr
         for eutrophic lakes.  Maximum net plankton community photosynthesis
         (Table 36) has dropped, since diversion, from 3400 (ETL) to a
         mean of 474 (ETL) and 575 mg.C/m2/day (WTL).  These latter
         values are in the range of borderline eutrophic lakes (Vollenweider,
         1968).
     3.  Secchi disc transparency (Table 12) averages are like those of
         moderately eutrophic lakes.

     How well does the degree of eutrophy, as assessed above, compare to
 that predicted by the loading models of Vollenweider  QL968, 1973) and
 Dillon (1974)?  Data for the models are summarized in Table 40.  The
 log phosphorus loading—log mean depth (1968) model indicates the lakes
 to be more eutrophic than they are, based on plankton data.  The 1973
 model (log phosphorus loading-log mean depth/water residence  (Tw))
 indicates the lakes to be moving towards mesotrophy, with WTL now (1974)
 mesotrophic and ETL eutrophic.  This position is supported by the evidence
 about plankton presented above, and is due in large part to the low
 water residence time.  Dillon's model places both lakes well into the
 eutrophic range, which they are not if only plankton-based indicators
 are employed.
     The Vollenweider (1973) model accurately predicts the degree of
 eutrophication of the Twin Lakes, as described by characteristics related
 primarily to plankton production.  However, nearly half the productivity
 of the lakes is due to macrophytes, and 25% of the area is littoral.
 The lakes are in fact of poorer quality, particularly from the view of
 the lake user than might be indicated by the mesotrophic label.  For
 planning or management purposes for lakes and watersheds of this type,
 models based primarily on plankton characteristics may not tje applicable,
 or are at least insensitive to the effects of very low mean depth.  We
 suggest a fruitful approach will include estimates of total community
 productivity for lakes with a mean depth less than 10 m. and a ratio
 of deep to shallow areas of less than 10 into classification models.
 Perhaps the 1968 model, which includes a factor primarily related to
 plankton biomass or productivity (phosphorus loading) and a factor
 primarily related to macrophyte growth (mean depth) is most applicable
 to shallow lakes, and the other models most applicable to deeper lakes.

                                  266

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                               Table 40

Summary Hydrologlcal and Limnological Data for Lake Classification  Models
A.
1 .
2.
3.
4.
5.
6.
7.
8.
9.
10.
1 1 .
12.
13.
14.
15.
16.
17.
18.
19.
20;
West Twin Lake
Lake Area (Ao), ha.
Lake Volume (V), m3 1
Mean Depth (2), M
Annual Outflow (Qo), m3
Annual 1 nf 1 ow (Q j ) , m*
Water Residence Time (Tw), yr.
V/Q
F 1 ush i ng Rate (p ) , Yr.~ 1
I/TW, Q/V
Areal Water Loading (?/Tw)
Phosphorus Loading (L), gms. P/m2/yr.
Outflow Phosphorus Amt. (L~Pna), kg./yr.
Inflow Phosphorus Amt. (L"P3j), kg./yr.
Retention Coefficient (ReXp)
"exp '
r\ , f p I
Ice Out, Mean Total P04-P Cone, (mg./m3)
Spring Circulation Period, Mean Total
P04-P Cone, (mg./m3)
Mean Summer Photic Zone Chlorophyl 1 A
Cone . (mg/m3 )
L (1 = Rovp)
P
Area of Land Drainage (Ad), ha.
Bas i n population ( C )
Per Capita Phosphorus Discharge (Ec)
Total Phosphorus Import ( [>3 j ) /Ad/yea r
1972
34.015
4.99 x I05
4.34
916835
I2I8I2I
1 .64
0.61
2.65
0.354
106. 16
120.52
0.337
212.0
137.0
28.58
0.205
184
-
65.5
1973 1974
34.015
1 4.99 x 1
4.34
826235
1 177684
1 .81
0.55
2.40
0.303
79.29
103.04
0.460
1 18.0
85.0
18.57
0.297
184
-
56.0
34.015
O5 14.99 x 1
4.34
1461576
1640332
1 .03
0.98
4.23
0.267
131 .69*
90.87
1 .291
94.0
78.0
23.54
-0.079*
184
1 124
0.08kg/
person/yea r
49.30
   Og.
^Apparently an  artifact.   L~Pl!a [PiD in 1974 was partly caused by  leaking
  sewer line which  crosses  lake outlet.

                                 267

-------
                                 Table 40
 Summary  Hydrological and  Limnological  Data  for  Lake  Classification  Models
B.
1 .
2.
3.
4.
5.
6.
7.
8.
9.
10.
1 1 .
12.
15.
14.
15.
16.
17.
18.
19.
20..
East Twin Lake
Lake Area (A0^» ha.
La ke Vo 1 ume ( V ) , m -1
Mean Depth (I), M
Annual Outflow (Qo) , m^
Annua 1 1 nf 1 ow (Q j ) , m3
Water Residence Time (Tw), Yr.
V/Q
F 1 ush i ng Rate ( p ) , Yr.~ '
I/TW, Q/V
Areal Water Loading (Z/TW)
Phosphorus Loading (L), gms . P/m^/yr.
Outflow Phosphorus Amt. (L~PHa), kg./yr.
Inflow Phosphorus Ami. ([P]j), kg-/yr.
Retention Coefficient (RexD^
90 CPDa
r - i
exp " Q| CP],
Ice Out, Mean Total P04~P Cone, (mg./m3
Spring Circulation Period, Mean Total
P04-P Cone, (mg./m3)
Mean Summer Photic Zone Chlorophyl 1 A
Cone, (mg./m-')
L (I _- Rexp)
P
Area of Land Drainage (Ad), ha.
Basin Population (C)
Per Capita Phosphorus Discharge (Ec)
Total Phosphorus Import ( [P] j ) /Ad/y r.
1972
26.88
1 3.50 x I05
5.03
1700006
1934340
0.79
1 .26
6.37
0.711
123.4
191.0
0.432
) 118.0
94.0
26.08
0.32 1
255

74.9
1973
26.88
13.50 x 1 O5
5.03
1444921
1678127
0.93
1 .07
5.4!
0.514
132.8
138.2
0. 173
75.0
65.0
19.14
0.397
255

54.20
1974
26.88
1 3.50 x 105
5.03
2307490
2458930
0.58
1.71
8.63
0.687
144.5
1 84.6
0.265
77.0
65.0
18.57
0.295
255
1510*
. 122kg/
cap i ta/yea r
72.39
     (mg.P/M2/yr)

'^Includes West Twin Lake sub-watershed  (184 ha.)  since WTL  drains
  Into  East Twin Lake.  Drainage areas obtained by  subtracting  lake  areas
  from  watershed area.  Small  lakes of watershed =  18  hectares.   Watershed
  area  =  334  hectares.
                                   268

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                           LITERATURE CITED

 1.   Cooke,  G.  D.,  T.  N.  Bhargava,  M. R.  McComas,  M.  C. Wilson,  and
        R.  T.  Heath,,   1973.   Some aspects of the phosphorus dynamics
        of  the  Twin Lakes Watershed.   In Modeling  the Eutrophication
        Process.   E.  J.  Middlebrooks, D.  H. Falkenberg,and T.E^
        Maloney (eds.).   Utah Water Research Laboratory, Logan,  Utah.
        PRWG 136-1

 2.   Dillon, P. J.  1974.   The phosphorus  budget of Cameron Lake,
        Ontario:   The importance of flushing rate  to  the degree  of
        eutrophy of lakes.  Limnol. Oceanogr.  20:28-39

 3.   Edmondson, W.  T.  1966.   Changes  in the oxygen deficit of Lake
        Washington.  Verh. Int.  Ver.  Limnol. 16:153-158,

 4.   Heath,  R.  T.  and G.  D.  Cooke.  1974.   The  significance of alkaline
        phosphatase in  a eutrophic  lake.   Verh.  Int. Ver. Limnol.
        19:(in  press)

 5.   Heinz,  M.H.E.F.  1971.  A limnological  study of the Twin Lakes,
        Portage County,  Ohio; the annual  variations of microcrustacea,
        and physical,  chemical,  and biological parameters.  M.S. Thesis:
        Kent State  University

 6.   Lardis, A. E.  1973.   A comparison of the  seasonal distribution of
        phosphorus  in the sediments of two  eutrophic  lakes, Portage
        County, Ohio.  M.S.  Thesis, Kent  State University

 7.   Long,  E.  B.  1971.  Biological  and physical evidence of eutrophication
        in  an Ohio  lake.   M.S. Thesis, Kent State  University

 8.	 and G. D. Cooke.  1971.  A  quantitative comparison of
        pigment extraction by membrane and  glass-fiber filters.
        Limnol. Oceanogr. 16:990-992

 9.   McNabb, C. D.  1960.   Enumeration of  freshwater phytoplankton
        concentrated on  the membrane  filter.  Limnol. Oceanogr.  5:57-61

10.   Mehta,  N.  C.,  J.  0.  Legg, C. A.  I. Goring, and C. A. Black. 1954.
        Determination of organic phosphorus in soils. I. Extraction
        method.  Soil Sci. Soc.  Amer. Proc. 18:443-449

11.   Ritchie, A.  and K.  L. Powell.  1973.  An inventory of Ohio soils -
        Portage County.  Ohio DNR, Division  of  Lands and Soils.  Progress
        Report  38

12.   Rogers, W. G.  1974.   Productivity study and phosphorus analysis of
        the macrophytes  in two eutrophic  lakes in  Northeastern Ohio.
        M.S. Thesis,  Kent State  University.

13.   Sakamoto,  M.   1966.   The chlorophyll amount in the eutrophic zone
        in  some Japanese lakes and  its significance in the photosynthetic
        production  of phytoplankton communities.  Bot. Mag. Tokyo 79:77-88.

                                   Z69

-------
14.  Tailing, J. F. 1957.   Photosynthetic characteristics of some
        freshwater plankton diatoms in relation to underwater radiation.
        New Phytol. 56:29-50

15.  ___^	 1965.   Comparative problems of phytoplankton pro-
        ductlon and photosynthetic productivity in a tropical and
        temperate lake.   Mem.  Inst. Itol. Idrobiol. 18(Suppl.):339-424

16.  Vollenweider, R.  A. 1968.   Scientific fundamentals of the
        eutrophication of lakes and flowing waters, with particular
        reference to nitrogen and phosphorus as factors in eutrophication
        OECD Tech. Rept.,  Paris DAS/CS1/68.27:1-182

17.	  	 1973.   Input-output models.  Schwerz. Z.
        Hydro 1". (in press)

18.  Wilbur,  D. L. 1974.  The effect of aluminum sulfate applications
        for eutrophic  lake restoration on benthic macroinvertebrates
        and the Northern Fathead Minnow (Pimephales Promelas Raf.)
        M.S.  Thesis, Kent State University

19.  Winslow, J. D. and G. W.  White.  1966.  Geology and groundwater
        resources of Portage County, Ohio.  U.S.G.S. Prof. Paper 511
                                   270

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                              SECTION V -  OREGON


                              WALDO LAKE, OREGON
                    Charles F. Powers, William D. Sanville
                              and Frank S. Stay
                 Corvallis Environmental Research Laboratory
                    U. S. Environmental Protection Agency
                              Corvallis, Oregon
                                 INTRODUCTION
     Waldo Lake, the second largest lake in Oregon, is one of the most pristine
lakes on record.  Located near the summit of the Cascade Mountains, the lake
was accessible only by foot or by a primitive road system until 1969, when a
paved road was constructed linking it with the Willamette Highway.  Three large
campgrounds have been developed on the east side of the lake by the U.S.  Forest
Service, and the lake has become subject to greatly increased summer recrea-
tional use over the past six years.  The Environmental Protection Agency began
limnological studies in 1969 to investigate possible effects of development on
this unique lake.  Except for the summers of 1969 and 1970, work has been con-
fined to one annual visit, in August or September, from 1970 to 1974.  Results
from 1969 and 1970 have been reported by Malueg et al. (1972).


                    GEOGRAPHICAL DESCRIPTION OF WALDO LAKE


     Waldo Lake is located at latitude 43°43'N, longitude 122°03'W, 1650 m
above mean sea level on the western slope of the Cascade Mountains (Fig.  1).
Precipitation amounts are moderately heavy, occurring for the most part in
the non-summer months (Table 1).  Average yearly precipitation is approxi-
mately 180 cm.  Evaporation is not measured at the lake, but is estimated as
approximately 109 cm annually from NOAA measurements in Detroit and Wickiup
Reservoir.  Between 1969 and 1973, yearly extreme temperatures varied between
-30° and 38°C.  Mean temperature for the period 1969-1972 was 6.0°C.  (All
precipitation, evaporation, and temperature information is from U.S. Depart-
ment of Commerce, NOAA, Environmental Data Service, Climatological Data).
                                     271

-------
45'41'00-N-f    \\

   I22'04'00"W •,
    LANE COUNTY, ORE.

  CONTOUR HTERVHL C METERS
DATE OF" SURVEY: 25,26 AUGUST »69
   Figure  1.   Bathymetrie  map of Waldo  Lake.
                             272

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                               Table 1
                  Precipitation Record, Waldo Lake
                  Ppt'n Since
                  Last Reading
Ppt'n Since
Date
Aug. '65
July '66
Aug.
Nov.
July '67
Oct.
Jan. '68
May
Aug.
Sept.
Oct.
Inches
Gage instal
54.20
0.20
12.80
—
3.70
18.80
25.10
5.15
—
4.05
Cm
led
137.7
0.5
32.5
—
9.4
47.8
63.8
13.1
—
10.3
Date
July '69
Oct.
Apr. '70
June
July
Sept.
April '71
Aug.
Oct. 7
Oct. 20
June '72
Inches
76.85
—
47.35
10.20
0.45
3.35
79.70
9.95
3.00
1.80
74.25
Cm
195.2
___
120.3
25.9
1.1
8.5
202.4
25.3
7.6
4.5
188.6
     The lake is surrounded by coniferous forest, predominantly Douglas
fir, pine, and hemlock.  A large meadow lies at the south end.   The soil
mantle is generally less than 1 m thick, consisting of moderately weathered
volcanic materials and glacially rounded boulders up to 1.5 m in diameter.
Underlying bedrock is principally hard basalt.   Numerous intermittent
streams, unchannelled runoff, and direct precipitation constitute the
lake's principal  sources of water.

     No permanent human population exists around the lake; however,
vacationers utilize camping facilities developed by the U. S. Forest
Service on the east side and the numerous hiking trails which radiate
from the area.  This use is for the most part confined to the period
July 15-September 15.  Fish production is low,  and fishing is of
relatively minor importance.  In 1973 the Forest Service estimated a
total of 27,900 vistor days for the campsites and 2100 additional, non-
camping visitor days by boaters and swimmers.  Figures for 1972 were
16,400 and 2,500 visitor days.  They estimate that use during 1971,
1970, and 1969 (when the campgrounds were opened) was comparable to
1972.  Drinking water for two of the campgrounds is taken from the lake.
                                                           3
Estimated daily water usage during the 1973 season was 45 m , with a
season's total of 2700 m3.
                                273

-------
     Sewage and effluent discharge is via septic tank drain fields and
drain seepage from outdoor faucets.  The discharge volumes are not
measured and the quantity and chemical quality of the ground water
entering the lake is not known.  Ground water and effluent movement away
from one septic tank drain field was measured in the summer of 1970
(Tilstra et al, 1973), but direct entrance of the effluent into the lake
was not demonstrated.

                       MORPHOMETRY AND HYDROLOGY

     The combined area of Waldo Lake and its watershed is 7900 ha (79
  p
km ).  The maximum length of the lake is 9.6 km on an approximate N-S
axis; maximum width is 4.3 km, and the surface area is 2700 ha.  Maximum
                                                           8  3
depth is 127 m, mean depth 35.6 m, and the volume, 9.5 x 10  m  (0.95
  o
km ).  The greatest depth (127 m) occurs in a restricted hole in the
northwest part of the lake; this is closely matched by a 125 m
depression near the south end.

     Thermal stratification has been observed each year, with an
epilimnion of 5-10 m thickness.  The ratio of epilimnion to hypolimnion
(E/H) is roughly 0.3.  Sufficient data are not at hand to permit
determination of the duration of stratification; it has been estimated
at five months.

     Little information exists on the nature of the lake sediments.  A
great deal of the bottom is rocky.  Sediments taken from the 127 m
location contained 0.2% total P, 0.9% total N, and 5.1% total C (dry wt)
(Malueg et al).  However, the areal extent of the sediments is not
known.

     There are no permanent influent streams.  The U. S. Geological
Survey maintains a recording gage on the outlet, the origin of the North
Fork of the Willamette River.  The average outflow for the period 1969-
1973 was 44.7 x 106 m3/yr  (1.42 m3/sec).  The retention time of the
lake, calculated as volume/outflow, is 21.2 years.
                                274

-------
                     LIMNOLOGICAL CHARACTERIZATION

     Limnological  observations are made at nine stations,  including  the
two deep holes.   Water quality differences from station to station are
slight, and in this report only data from the North  Hole (the  deepest
point in the lake) are reported.


                        PHYSICAL CHARACTERISTICS

      As noted previously the lake stratifies thermally.  Midsummer
 surface temperatures range between 14° and 18° C; minimum deep water
 temperatures of 3.9° and 3.8° C were observed in 1972 and 1974,
 respectively.  Temperatures from the North Hole for 1969-1974 are  listed
 in Table 2.

                                  Table 2
                                North Hole
                              Temperature, °C
                                  August
Depth, m
0
5
10
15
20
25
30
40
50
60
70
80
90
100
1969
16.6
16.6
13.1
9.8
7.9
6.7
6.1
5.3
5.0
4.6
4.4
4.3
4.2
4.1
1970
18.0
17.9
17.2
11.6
9.3
7.7
6.5
5.6
5.1
4.8
4.6
4.6
4.5
4.4
1971
17.5
16.8
12.0
10.0
8.0
7.8
6.4
5.5
5.1
4.9
4.6
4.5
4.5
4.4
1972
14.1
13.9
13.8
10.6
7.3
7.1
6.4
5.2
4.3
4.1
3.9
3.9
3.9
3.9
1973
16.5
16.0
13.6
10.5
9.1
8.0
7.4
6.3
5.7
5.3
4.8
4.6
4.4
4.4
1974
—
15.4
11.7
8.6
7.3
6.1
5.6
5.0
4.3
4.0
4.0
3.8
3.8
3.8
                                 275

-------
     Specific conductance of the lake waters is extremely low, ranging
between 2.0 and 5.0 ymhos/cm at 25°C (Table 3).  This reflects the very
dilute concentration of all solutes for which determinations have been
made; total solids as determined by Malueg et al were nearly
undetectable at 3 mg/1.

                                Table 3
                 Specific Conductance, ymhos/cm @25°C
                                August
Depth, m       1969      1970
   0            3.2
  20            3.2
  40            3.0
  60            2.9
  80            3.0
  100            2.9
1971
3.4
3.1
2.9
2.9
2.9
2.8
1972
3.0
—
3.0
3.0
3.0
3.0
1973
4.0
3.9
3.8
3.6
3.5
3.5
1974
5.0
4.0
4.0
—
4.0
4.0
     Measurements taken with a white 20-cm secchi disc have shown
considerable variation during our period of record.  In 1969 values from
24.0 to 32.5 m were obtained between June and September.  Observations
since  1969  have been as follows:

                              1970 — 27.5 m
                              1971 -- (missing)
                              1972 — 25.0 m
                              1973 -- 23.0 m
                              1974 -- 35.0 m

Fluctuations in secchi disc transparency appear to be caused by
meteorological conditions and coniferous pollen rather than by the
presence of phytoplankton.
                                  276

-------
 CHEMICAL CHARACTERISTICS

      Total  alkalinity (Table 4)  ranges  between  1.0  and  3.0  mg/1  (as
CaCO,), with essentially uniform distribution from surface to bottom.
Accurate determinations of pH are difficult because  of the extremely low
buffering capacity and dissolved solids  content of the water.  Levels  of
pH are consistently less than 7.0 except for the 1972 measurements,
which are suspect (Table 5).  Measurements in 1974 were made with a
Hydrolab Surveyor Model 6D in situ water quality analyzer, and would be
expected to be of greater accuracy than  earlier determinations made in
vitro.
                                  Table 4
                                North Hole
                             Total Alkalinity
                                mg/1 CaC03
                                  August
Depth, m
0
20
40
60
80
100
1969
2.0
1.0
1.0
1.0
1.0
1.0
1970
2.0
2.0
2.0
2.0
2.0
2.0
1971
—
2.0
2.0
2.0
1.0
2.0
1972
2.0
—
2.0
2.0
2.0
2.0
1973
1.0
1.0
1.0
1.0
3.0
1.0
1974
1.0
2.0
2.0
3.0
2.0
3.0
   Depth,  m
      0
     20
     40
     60
     80
    100
1969
 5.5
 5.4
 5.3
 5.3
 5.2
 5.2




1970
6.6
6.3
6.2
6.2
6.4
6.3
Table 5
North Hole
pH
August
1971
6.3
6.3
6.3
6.3
6.1
6.0
1972
 7.1

 7.1
 7.2
 7.1
 6.8
1973
1974
 6.4
 5.6
 6.0
 5.0*
 5.3*
 5.1*
   *Data from South Hole
                                   277

-------
      Dissolved oxygen  exhibits an orthograde distribution as would be
 expected  in  such  an  extremely unproductive lake.  Epilimnetic values are
 usually about 2 mg/1 lower  than at greater depths.  Percent saturation
 varies  between 89 and  114,  and is usually very near 100 percent.
 Dissolved oxygen  distribution is summarized in Table 6.

                                 Table 6
                               North Hole
                         Dissolved Oxygen, mg/1
                                 August
Depth, m
0
20
40
60
80
100
1969
8.1
10.3
11.2
10.8
10.9
10.7
1970
7.7
10.4
10.8
10.7
10.8
9.4
1971
8.2
9.8
10.4
10.2
10.7
10.2
1972
8.5
--
10.5
10.5
11.0
10.6
1973
8.5
10.8
11.2
11.2
11.2
11.2
1974
8.1
10.2
10.8
10.1
10.0
9.5
     Phosphorus measurements have consisted of total  and orthophosphate
phosphorus.  Concentrations of both forms are consistently below 5 yg/1,
and significant differences or trends cannot be distinguished within the
limits of the analytical  technique.  Nitrite, nitrate,  and ammonia
nitrogen are almost invariably below this laboratory's  minimum detection
limit of 10 ug/1 and apparent differences are probably  due to analytical
limitations.

     Chlorophyll ^determinations have been made on North Hole samples
for each year of the study.  The reliability of the data for 1971  and
1972 are uncertain, although the expected very low pigment levels  were
indicated.  Chlorophyll  a_ was not detectable in the 1973 samples.
Measurements for 1969, 1970, and 1974 are given in Table 7.   Values are
consistently below 1.0 vig/1, and exhibit no trends over the five year
period of record.
                                   278

-------
                                Table 7
                              North Hole
                             Chlorophyll a_
                                 U9/1
          Depth          Sept.          August         August
                 m            1969            1970           1974
                 0            0.4            0.1            0.2
                20            0.6            0.1            0.1
                40            0.2            0.4            0.1
                60            0.2            0.6            0.2
                80            0.6            0.7            0.2
                100            0.5            0.2            0.4
     Primary productivity measurements by Larson and Donaldson (1970)
showed an average carbon uptake rate in the summer of 1969 of 38 mg
   2
C/m /day.  Powers et al (1972) showed carbon uptake rates in the summer
                                            •j
of 1970 ranging between 0.03 and 0.10 mg C/m /hr.  Both sets of data
indicate extremely low productivity rates.
     Laboratory algal assay tests were conducted on Waldo Lake water by
Miller et al (1974).  Autclaved-filtered water did not support growth
beyond 0.06 mg dry wt/1, even with the addition of 1.0 mg N/l and 0.05
mg P/l.  However, in the in situ primary productivity experiments
carried out by Powers et al, addition of 0.05 mg P/l alone increased
photosynthetic rate on three of four occasions.  The influence of
phosphorus plus nitrogen was not significantly different from the effect
of phosphorus alone.

     Summaries of algal cell counts and group identifications are
presented in Table 8.   Clump counts were made on a Sedgwick-Rafter
cell, using concentrated samples prepared by settling 500 ml to 50 ml
over a 12-day period.  In the clump count method, all unicellular,
colonial, and aggregated organisms are tallied as single units, and have
equal numerical weight.  Samples obtained in 1973 and 1974 have not been
processed.
                                  279

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                                     Table  8
                                   North  Hole
                                  Phytoplankton
                                  organisms/ml
0
10
20
30

21
21
2
7
94
103
67
19
86
20
30
40
70

10
10
2
4
19
25
2
197

199
1969
Depth,
40
10
10
90
110
1970
10
10
10
1971
20
2
22
1972
594
5
599
m
60
30
150
180
10
10
^
10
184
2
186
2
857

859
80
10
190
200
10

10
177
10
187
3
379

381
100
10
10
120
140



100
1
101
728

728
Diatoms
Greens
Blue-greens
Dinoflagellates
Unknown
Total
Diatoms
Greens
Blue-Greens
Dinoflagellates
Unknown
Total
Diatoms
Greens
Blue-Greens
Dinoflagellates
Unknown
Total
Diatoms
Greens
Blue-Greens
Dinoflagellates
Unknown
Total
     Although Larson and Donaldson (1970) reported an average of 4.5
organisms per #6 net tow near shore, Malueg et al reported no
zooplankton.  Repeated vertical tows from the deep stations and near
shore horizontal tows, using a 0.5 m #10 plankton net, have failed to
produce a single zooplankter during our entire study.
     The extreme clarity of the lake is emphasized by the presence of

 the hepatic, Jungermannia triris Nees, and a moss Hygrohypnum

 (molle?), at the bottom of the North Hole at 127*m.
                                   280

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                           NUTRIENT BUDGETS

     Sources of nutrients to Waldo Lake are precipitation (principally
snow), intermittent surface runoff, and ground water.   Septic tank
drainage from campgrounds is a presumed source, although the 1973 study
did not demonstrate transport of effluent to the lake.   There are no
permanent tributaries.  The 30,000 visitor days estimated by the Forest
Service for 1973, when prorated over an entire year,  are equivalent to a
permanent population of 82 persons (30,000/365 = 82).   Assuming an
average phosphorus loading rate of 1.1  kg P/capita/yr,  this amounts to
93 kg P/yr, or 0.003 g P/m2/yr to the lake.

     Lacking measurements of surface and ground water contributions, it
is not possible to measure directly the nutrient loadings to the lake.
Phosphorus and nitrogen budgets have therefore been calculated by
several different indirect methods.  Constants used in  the calculations
include:

     Average annual precipitation = 181.4 cm
     Estimated annual evaporation = 109 cm
     Catchment area of lake (including lake surface)  =  7900 ha
     Surface area of lake = 2700 ha
                                        /•  ^
     Average outflow from lake = 45 x 10  m /yr
     Average total P concentration of outflow = 3.5 yg/1
     Average total P concentration of lake =3.5 ug/1
     Average total P concentration of precipitation on  catchment area =
          5 yg/1 (after Malueg et al)
     Average N concentration of precipitation on catchment area =
          83 yg/1 (after Malueg et al).
                                   281

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PHOSPHORUS

     1.   Using information from Vollenweider (Input-Output Models),
assume that P loading is three times the measured lake concentration and
also (in this case) three times the measured phosphrous flowing out of
the lake:

     Measured P out = 157.5 kg/yr
              P in  = 3 x 157.5 = 472.5 kg/yr = 0.0175 g P/m2/yr.

     2.   Using unpublished data of Miller, assume from the innate
characteristics of the watershed that P loading to Waldo Lake is the
same as that from undisturbed forest land in the Upper Klamath Lake,
                            o
Oregon, drainage (5.25 kg/km /yr):

     Waldo Lake watershed = 5200 ha
     5200 x 0.052 kg P/ha/yr = 270 kg P/yr = 0.01 g P/m2/yr.

     3.   Using average annual precipitation for the Waldo Lake
watershed, and snow analyses of Malueg et al:

          (a)  Assume that all precipitation onto the watershed eventually
               enters the lake, and that the total P content of the
                                        3
               precipitation is 5 mg P/m :

                    (143.4 x 106 m3 water) (5 mg P/m3) = 716.5 kg
                    P/yr to lake = 0.027 g P/m2/yr.

          (b)  Assume that only that part of the precipitation equal to
               the measured outflow plus the estimated evaporation from
               the lake actually enters the lake:
                                    282

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                    measured outflow = 45 x 10  m /yr
                    est. evaporation = 29 x TO  m /yr
                    runoff to lake   = 74 x 106 m3/yr, (74 x 106)(5 mg P)
                                     = 370 kg P/yr = 0.014 g P/m2/yr.
     4.   Using information from Vollenweider and Dillon (1974),  Tables
                                                                 2
5 and 6, assume a total P soil export factor of 0.010 g total  P/m  of
land/year.  This is the value used by Patalas (1972) for Lake  Superior
(igneous forested land).
     Area of Waldo Lake watershed = 5200 ha
     5200 x 0.01 = 5.2 x 105 g/m2 P from watershed soil/year.
     Assume remainder of P loading is via direct precipitation onto lake
surface:

     (1.81 m3 ppt'n/yr)(27 x 106 m2 lake surface)
                 /TO                                   O
     = 48.87 x 10  m  ppt'n onto lake surface x 5 mg P/m
     = 2.4 x 105 g P.
       5.2 x 105 g P from soil  + 2.4 x 105 g P from ppt'n
     = 7.6 x 105 g P to lake =  0.028 g P/m2/yr.
NITROGEN

     Total nitrogen loading to the lake has been estimated by methods  2,
3a, and 3b (above).  Method 1, in which measured output was related  to
input in the phosphorus estimates, has not been attempted for nitrogen
because estimates of nitrogen retention in lakes are even more tenuous
than for phosphorus.  Method 4 could not be used because of lack  of
information on soil loading.
                                  283

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     Method 2.  Using unpublished data of Miller for the Upper Klamath
                                           2
Lake watershed, assume N loading = 22 kg/km /yr:
          Waldo Lake watershed = 5200 ha
          5200 x 0.22 kg N/ha/yr = 1144 kg N/yr = 0.042 g N/m2/yr.
     Method 3a.  Using average annual  precipitation for the Waldo Lake
watershed, and snow analyses of Malueg et al:

          (a)  Assume that all precipitation  onto the catchment area
               eventually enters the lake, and that total  N content is
               83 mg N/m3:  (143.3 x 106) (83 mg N/m3) = 11,894 kg N/yr
               to lake = 0.44 g N/m2/yr.

                                                   fi  ^
          (b)  Assume that runoff to lake = 74 x 10  m /yr (outflow plus
               evaporation):

               (74 x 106)(83 mg N) = 6142 kg  N/yr = 0.23 g N/m2/yr.
                              DISCUSSION

     All available limnological  criteria confirm the extremely pristine
state of Waldo Lake.  Comparisons with Crater Lake and Lake Tahoe,  two
other well-known ultraoligotrophic lakes, show that Waldo Lake's
specific conductance is one to two orders of magnitude less and its
total dissolved solids an order of magnitude less.  Secchi disc values
for Waldo fall within the range for Tahoe and Crater.  Based on our 1969
and 1970 measurements, primary productivity in Waldo is significantly
less than in the other two, as are phytoplankton numbers.  As stated
earlier, zooplankton have not been found at any time during our
investigations of Waldo Lake.
                                  284

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     Based on the calculated loading rates for phosphorus and nitrogen,
Waldo Lake falls near the extreme lower end of the "Vollenweider scale."
Using the highest rates yielded by the several estimates,

                    P = 0.028 g P/m2/yr
                    N = 0.44 g N/m2/yr
                    (N/P loading ratio = 15.7).

The ratio of mean depth to retention time is 1.68.  Because of this low
value, the lake, when entered on a plot of P loading vs mean
depth/retention time, falls near the lower left portion of the diagram
in the critical part of the oligotrophic region, implying that a
relatively slight increase in phosphorus loading could strongly alter
the trophic status.   Such an implication appears to be substantiated by
the primary productivity experiments of Powers et al where phosphorus
was shown to stimulate photosynthetic activity.   However, Miller et al
were unable to increase algal production with an addition of phosphorus
alone or phosphorus  plus nitrogen, indicating that nutrients in addition
to nitrogen and phosphorus were limiting to algal growth.  This could
well be the case in  a lake where all dissolved constituents are in very
low concentration.  The relative importance of phosphorus in Waldo Lake
is therefore uncertain, but there is no question that introduction of
nutrient or polluting materials of any kind to such a unique resource
should be held to a  minimum.  Increased concentrations of micronutrients
could result in a condition where slight increases in phosphorus loading
could significantly  change the trophic state.

                                SUMMARY

     Waldo Lake, in  the Cascade Mountains of Oregon, is extremely
oligotrophic, ranking amount the most pristine lakes of the world.  The
recent development of access roads and campground facilities has raised
                                  285

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questions concerning the possible response of the lake  to  the  pressures
of increased recreational  use,  and was the primary reason  for  the
inception of our studies.   The  lake has no permanent tributaries,  and
the hydrologic and nutrient budgets are not amenable to accurate
measurement.  Several different methods of estimation place the rates  of
                                                     2
phosphrous and nitrogen loading at 0.028 and 0.44 g/m yr,  respectively.
The N/P loading ratio is 15.7.   On the "Vollenweider scale" the lake is
definitely oligotrophic, but lies in that area of the diagram  where
relatively small increases in P loading are significant.   However, the
relative importance of phosphorus in Waldo Lake is uncertain because of
the very low concentrations of  all measured nutrients.
                              REFERENCES

Larson, D. W., and J. R. Donaldson.  1970.  Waldo Lake, Oregon:  A
     special study.  Water Resources Research Institute Report No. 2,
     Oregon State Univ.  21 p.

Malueg, K. W., J. R. Tilstra, D. W. Schults and C. F. Powers.  1972.
     Limnological observations on an ultraoligotrophic lake in Oregon,
     U.S.A.  Verh. Internat. Verein. Limnol., 18:292-302.

Miller, W. E., Pacific Northwest Environmental Research Laboratory,
     Corvallis, Oregon.  Personal Communication.

Miller, W. E., T. E. Maloney, and J. C. Greene.  1974.  Algal
     productivity in 49 lake waters as determined by algal assays.
     Water Research, 8:667-679.

National Oceanographic and Atmospheric Administration, Environmental
     Data Service.  1969-1973.  Climatological Data.  Vols. 75-79.

Patalas, K.  1972.  Crustacean plankton and the eutrophication of the
     St. Lawrence Great Lakes.  J. Fish. Res. Bd. Canada, 29:1451-1462.
                                  286

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Powers, C. F., D. W. Schults, K. W.  Malueg, R.  M.  Bn'ce,  and M.  D.
     Schuldt.  1972.  Algal responses to nutrient  additions in natural
     waters.  II.  Field experiments.  Iru   Nutrients and
     Eutrophication, Special  Symposia, Vol. I,  Amer.  Soc. Limnol.
     Oceanog., p. 141-154.

Tilstra, J. R., K. W. Malueg, and C. F. Powers. 1973.  A study  on
     disposal of campground wastes adjacent to  Waldo  Lake, Oregon.
     Working Paper #7, Pacific Northwest Environmental  Research
     Laboratory, EPA, Corvallis, OR, 22 p.

Vollenweider, R. A.   Input-output models.   Unpublished  manuscript.

Vollenweider, R. A., and P. J. Dillon.  1974.   The application of the
     phosphorus loading concept to eutrophication  research.   National
     Research Council Canada  Rpt. No. 13690,  Ottawa,  Ontario.  42 p.
                                 287

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                          SECTION VI - WASHINGTON


                               LAKE WASHINGTON


                              W. T. Edmondson
                            Department of Zoology
                           University of Washington
                             Seattle, Washington
                              I.  INTRODUCTION


     A. History.  In its natural state, Lake Washington drained from the south
end through the Black River into the Duwamish estuary and Puget Sound.  It had
one major inlet, the Sammamish River from Lake Sammamish, and about a dozen
small streams.  In the 1890s a small cut was made between Union Bay of Lake
Washington and Portage Bay of Lake Union to permit passage of logs to a sawmill.
Later this cut was enlarged and a canal with locks made, between Lake Union and
Puget Sound.  It opened in 1916, at which time the level of the lake was lowered
by about 3.3 m  (10 feet) and the Cedar River was diverted into the south end of
the lake.  In the 1940s and 1950s small amounts of salt water entered Lake
Washington and formed a transitory layer of very dilute sea water in the deep-
est parts.  The latest intrusion was in 1952.

                         II.  GEOGRAPHIC DESCRIPTION

     A.  Latitude 47° 38' N.  Longitude 122° 14.5' W.

     B.  The level of the lake is regulated between 6.1 and 6.7 m above mean
low water in Puget Sound except in unusually dry years.  The lowest level,
5.6 m, occurred in 1958.

     C.  The catchment area of land including Mercer Island in the lake is
1588 km2.  The water area is 88 km2, total 1676 km2.

     D.  General climatic data  (1931>-1960).  Monthly mean air temperatures
vary from 5.1°C (41.2°F) in January to 18.67°C  (65.6°F) in July.

     Rainfall varies from a monthly mean of 1.6 cm  (0.63 in.) in July to
13.77  cm  (5.42  in.) in December.  Yearly mean 86.61 cm  (34.1 in.), range
48.58  cm to 114.07 cm.

     In general, winds are from the southerly directions most frequently in
winter, northerly in summer.  The strongest winds come  from southwest in spring
or early summer.  The mean velocity at Sand Point is 11.1 km/hr  (6.9 mph).

     Total evaporation is about the same as the rainfall with an average excess
of rainfall of  about 3 cm.  Net monthly evaporation varies from -14.1 cm to
+13.1  cm.                              288

-------
     The lake never freezes across.   In the most severe winters
thin ice can develop in the bays, but this is a rare occurrence.

     E.  General geological characteristics.  The lake occupies
a deep, narrow through sculptured by the Vashon ice sheet.   Most
of the upland area is occupied with glacial till covered with a
few feet of weathered soil.  In the lowland valleys, alluvial
deposits of clay are prevalent with sand and gravel deposits in
places.  Erosion appears not to be a major problem.

     F.   Vegetation.

     The original vegetation was a thick forest dominated
by Douglas fir (Pseudotsuga menziesii), red cedar (Thuja
plicata) and western hemlock (Tsuga heterophylla).   Spruce
(Picea si t chens is) and fir (Abies grandis) were less common
(Scott, 1962).  Red alder (Alnus rubra) and cottonwood
(Populus trichocarpa) were the only abundant deciduous trees.
They grew on river floodplains and as pioneer trees on other
disturbed sites.

     The second- or third-growth forests currently around
Seattle have a different distribution of species.  In cut-
over areas, red alder has become much more abundant, some-
times being the dominant species for a time.  Alder dominance
last 30-50 years, until conifers regenerate and overtop the
alder.  The success of alder varies, depending on soils and
fire.  Douglas fir grows with alder in many areas,  cottonwood
is sometimes common and willow is an important pioneer on
other sites.  Burning of slash and brush after clear-cutting,
a frequent occurrence in the early years of this century,
destroyed the conifer seed in the soil, encouraging the
growth of alder, which has abundant and easily transported
seeds.  Large areas from which conifers had been removed
completely were without a source for conifer seed and went
over completely to alder forest and brush (modified from
Davis, 1973).

     The Cedar River watershed is under control of the Seattle
Water Department.  While it has been intensively managed, the
characteristics of the soil are such that erosion into the
Cedar River is not a serious problem.

     G.  Population.  The lowland area is heavily urbanized, but
most of the Cedar River watershed is fenced and uninhabited because
it is the major source of water for the metropolitan area.   The
city of Seattle borders much of the west side of the lake and
several small towns are at the ends and on the east side.  The
human population within the Lake Washington watershed is approxi-
mately 525,000.
                                 289

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     H.  Land use.  In the Lake Washington watershed,  land use
includes residential, commercial and industrial,  but large areas
are undeveloped.  Intensive lumbering takes place in the Cedar River
watershed, which is otherwise largely undeveloped.   A relatively
small amount of agriculture is done, mostly in the Sammamish River
area.

     Shoreline use:  residential, 64.5%;  recreation, 19.0; unde-
veloped, 7.1; public service, 3.7; industrial, 2.8;  commercial,
1.6; private club, 0.8; circulation and utilities,  0.5.

     I.  Use of water.  To a large extent Lake Washington is used
as a recreational amenity for boating, fishing and swimming.  Com-
mercial traffic on the lake consists mainly of rafted logs and of
barges of sand and gravel in transit to construction companies.
A commercial flying service at the north end of the lake and about
thirty private planes use the lake for landing.

     A Naval Air Station at Sand Point was partly deactivated in
1970, and recently a large part of the area has been released for
two developments.  One will be a public park, the other will be
an establishment at which NOAA will station its ships and have
some research and administrative activities.

     The lake itself is no longer used as a general source of
drinking water, but the Cedar River is a primary source of water
for Seattle and a number of smaller towns in the area.  It is
also a spawning area for an important run of sockeye salmon, so
there is public pressure to maintain an adquate flow.

     An unusual feature of Lake Washington is the two multilane
floating bridges that carry more than 85,000 vehicle crossings per
day.

     J.  Sewage.  The maximum input of treated secondary effluent
took place in 1962, for in March 1963 a program of diversion was
put into effect.  The amount of sewage was progressively decreased
from about 76,000 m  per day (20 million gallons), and the project
was finished in 1968.  Seattle has had combined sewer systems with
storm overflows into Lake Washington.  At the present, a project
of sewer separation is being carried out.  There has been no major
source of industrial waste, although the Boeing Company put a waste
rich in phosphate into the Cedar River in the 1950s.  In the late
1950s some of the streams carried septic tank overflow, but this
has been greatly reduced by local sewerage projects.

III.  Description of Lake Washington.

     A.  Area 87.615 km2
         Length 21 km
         Width:  maximum 5.5 km, mean about 3

                                  290_

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     B.  Volume 2885.3 million m3

     C.  Maximum depth 62.5 m (approx)
         Average depth 32.9 m

     D.  The deepest parts are shallow grooves or troughs between
the middle and sides.  About 83% of the lake is deeper than 10 m.

     E.  Typically the epilimnion is 10 m thick, and the E:H ratio
then is 0.387.

     F.  The lake is monomictic.  Secure stratification is usually
established about the middle of May, although in calm years tran-
sitory stratification occurs in April and in windy years stratifi-
cation may be delayed until June.  Maximum temperature occurs in
August.  The lake begins to cool then and the epilimnion thickens
progressively until homothermal conditions are established in
November or December.  During very cold weather, cold water masses
form in the shallower bays and slide down to the bottom of the lake
and out toward the middle, causing decreases in temperature that
cannot be accounted for by mixing.

     G.  The deep sediments are a black planktogenic gyttja, dominated
by diatom frustules.  In shallow water most of the bottom is covered
with boulders, gravel and sand.

     H.  At Seattle the maximum mean monthly rainfall is 13.8 cm
(5.42 in) in December, the minimum 1.6 cm (0.63 in) in July.  The
extremes for individual months have been a trace in July and 38.9
cm (15.33 in) in January 1880.  The maximum during the period of
recovery from eutrophication was 25.6 cm (10.07 in) in December
1968.  Annual total rainfall has varied from 143.4 cm in 1879 to
49.6 cm in 1952 (56.44 in to 19.52 in).  Rainfall is greater in
the upper part of the Cedar River watershed and heavy snows occur
in some years.

     I.  Inflow and outflow of water.  According to calculations
by a hydrological model developed for METRO, the mean volume of
water entering-through all inlets in the period 1942-1972 was
1211 million m  per year.  The minimum was 466.9 million m  in
1944 and the maximum 1681.8 million m  in 1950.  The Cedar River
is responsible for about half the total flow.  Of the rest, the
Sammamish River contributes about 72%, the other 28% being brought
in by the various small streams around the lake.  Thus, the two
main rivers account for about 86% of the total inflow,
                                                                  3
     The mean rainfall of 0.8661 m amounts to about 75.9 million m
falling directly on the lake.  The volume of the lake is 2885.3
million m .

     Nothing quantitative is known about ground water.

                                  291

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     J.  Surface water currents have been studied by METRO using
dye patches and streaks.   No consistent current pattern exists.
The drift from inlets to outlet is masked by wind-blown currents,
but the movement of water is not clearly and directly related
to momentary wind direction, evidently because of the constraints
of the shores, and because of delayed effects of previous wind
conditions.

     K.  Water renewal time.  By dividing the volumes of inflow
listed in Part I above into the volume of the lake,  the following
retention times for calendar years are obtained:  mean 2.38 years,
maximum 6.18 years (1944), minimum 1.72 years (1950).  For 1957
when the first loading was calculated, it was 2.97 years by the
model, 3.32 by calculations using U.S.G.S. gauge data.

     The reciprocals of the numbers given above, the renewal rates
per year are, in order:  0.420, 0.162, 0.583, and for 1957 (model)
0.336.

IV.  Limnological characterization.

     A. Physical

        1.  Temperature.  Surface temperature in the open water
varies from about 6  to about 25  C.  The maximum temperature at
the bottom in summer is about 8 .

        2.  Conductivity in recent years has varied between 76 and
87 ymhos.

        3.  Light.  Some measurements of light penetration have been
made with a photometer and many Secchi disc measurements of trans-
parency taken.  During the period of eutrophication at a time when
the Secchi disc transparency was 1.1 m, 10% of the surface light
intensity occurred at 2.4 m.  During the period of de-eutrophication,
Secchi values have increased, and the maximum value ever observed,
7.5 m, occurred in February 1975.  The largest summer value ever
observed, 5.5 m, occurred in July, 1975.
        4.  Lake Washington has no measureable humic color.  When
the lake is clearest in the winter, the Secchi disc appears green.

        5.  Solar radiation.  During June-September, the mean daily
solar radiation has varied between 391 and 468 langleys.

     B. Chemical

        1.  The maximum pH  occurs during  the spring and summer when
primary production is maximum.  The highest value in 1933 was 8.6.
                                   292

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During the eutrophic years it got as high as 9.9 in 1963 and progress-
ively decreased over the years, getting down to 8.5 in 1973, although
it went back to 8.96 in 1974.

        2.  Dissolved oxygen.  Although large volumes of the lake did
not become anoxic during the period of eutrophication, values less
than 5.0 were prevalent in late summer.  Since diversion of sewage,
oxygen concentrations in the hypolimnion remain in the order of 8
mgm/1.

        3.  Total phosphorus has varied greatly over the years with
different degrees of eutrophication.  The maximum annual mean was
65.7 yg/1 in 1963, minimum 16.8 in 1973.  Mean dissolved inorganic
phosphate P in January-March was 56.9 yg/1 in 1964, 8.8 in 1972.

        4.  Nitrogen has varied considerably, but not as much as
phosphorus.  The mean in January-March of inorganic N was 495 yg/1
in 1965, 313 in 1973.

        5.  Alkalinity has not varied a great deal, being about 20-30
yg/1 expressed as CaCO .

        6.  Few complete ion analyses are available for Lake
Washington.  A typical analysis, from 1969, is:

            Ca  8.8      HCO   40.0     TDS  54
            Mg  3.3      SO/3  8.2
            Na  4.6      Cl4   3.1      (all as mg/1)
            K   1.1      SiO   8.6

        7.  Few trace metal analyses has been published for the
water of Lake Washington, although there is considerable interest
in the sediments.  The lake has been relatively enriched in a
number of trace elements by emissions from a smelter near Tacoma
40 miles to the south.

     C.  Biological

         1.  Phytoplankton

             a.  Chlorophyll.  The mean chlorophyll  in summer was
41.0 yg/1 in 1964, 4.8 in 1973.

             b.  Primary production (see Table 1).

             c.  Algal assays.  In recent years, the natural
population of phytoplankton has tended to respond to addition of
phosphate more than to addition of nitrate in bottle tests.  In
the mid 1960s when the lake was still enriched with sewage, it
tended not to be responsive to added phosphate.
                                  293

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             d.  Lake Washington has characteristically had a
spring bloom of diatoms dominated by Stephanodiscus,  Fragilaria,
Melosira and Asterionella.  In 1933 and 1950, the summer population
was mostly a small mixture o£ species of green algae and some
flagellates.  During the period of eutrophication this basic
pattern had superimposed on it a dense population of blue-green
algae in the summer.  The blue-greens included Oscillatoria
rubescens, 0_. agardhii, Micro cyst is, Anabaena and A phanizomenon.

         2.  Zooplankton.  The most abundant zooplankton include
Diaptomus. ashlandi, Epischura lacustris, two species of Cyclops,
Diaphanosoma leuchtenbergianum and Bosmina longirostris.  Several
species of rotifers become prominent, the most prevalent being
Keratella cochlearis and Kellicottia longispina.

         3.  The bottom fauna is dominated by a variety of
chironomids, with lesser numbers of tubificids and small molluscs
(Pisidium).

         4.  Fish.  A variety of species of fish live in the lake.
Of special interest is the sockeye salmon (Onehorhynchus nerka)
which became abundant in 1964 and is heavily fished.

         5.  Bacteria.  Dr. James Staley is studying the bacteria
with special attention to Metallogenium and Caulobacter.

         6.  Bottom flora and macrophytes.  No systematic study
appears to have been made.  Genera growing in shallows include
Potamogeton, Myriophyllum, Naj as, Anacharis, and Ceratophyllum.
Emergent plants include Scirpus, Typha and Sagittaria.

V.  Nutrient Budget Summary.

    The nutrient input to the lake varied greatly with the increase
of sewage and then with the diversion.  Data are summarized
in Table 2.
                                   294

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Table 1.  Primary production in Lake Washington
A.   Gross oxygen production, g/m^/day in 24 hour runs

                      July-Aug.            June-Sept.

1-958                     	                 4.2
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
                  4.2
                  3.0
                  4.8
                  5.2

                  4.6
                  2.7
                  3.3
                  0.9
                  1.2
                  1.8
                  1.4
                  1.8
                  1.2
4.0
3.8
4.6
4.7
3.3
3.7
2.7
3.0
1.1
1.4
2.0
1.4
1.7
1.0
                                                        Year
                                                         2.1
    1.9
    2.0
    3.3
    3.7
    2.2
    2.3
    2.0
    1.9
    0.9
    1.2
    1.3
    1.3
    1.4
    0.8
B.
     14
C fixation in 24 hour runs
                                 Annual
1972
1973
1974
1975
1976
                        Mean

                      mg/m^/day
                  198
                  282
                  371
                  187
                                     Total

                                   gm/m^/year
 72
103
135
 68
June-Sept.

     f\
 mg/m^/day

    246
    265
    353
    493
    219
Note:  Measurements of carbon uptake rates were started in 1963,
but were not done often enough to permit calculation of means
in the earlier years.
                                   295

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Table 2.  Nutrient income to Lake Washington,  kg/year
A.  Income

1957
Phosphorus

Streams
Sewage plant effluent
Industrial waste (est.)
Septic tank drainage (est.)
Combined sewer overflow (est.)
Total wastes

Total (full)
Total - septic tanks
      - combined sewers

Nitrogen

Streams
Sewage plant effluent
Industrial waste (est.)
Septic tank drainage (est.)
Combined sewer overflow (est.)
Total wastes

Total (full)
Total - septic tanks
      - combined sewers
  Total P
   42,600
   42,100
    7,800
    8,600
    7,100
   65,600

  108,200
   99,600
   92,500
 Total N
1,471,000
  172,600
1,688,900
1,672,800
1,654,200
  Dissolved P
    36,000
    37,900
     7,800
     7,800
     6,500
    60,000

    96,000
    88,200
    81,700
Dissolved N
 1,331,000
   133,300
    10,600
    16,100
    18,600
   178,600
 1,509,600
 1.493.500
 1,474,900
Nitrate-N
 253,100
  19,600
 272,700
Data from Hollis M. Phillips, Seattle Department of Engineering.
Stream values based on measurements of concentration and flow.  Flow
data for two rivers and two small streams from U.S.G.S.  Other flow data
estimated from drainage area.  Septic tank drainage, combined sewer over-
flow and industrial waste estimates from Brown and Caldwell.  The full
total of all items listed is probably an overestimate since some of the
septic tank drainage would have entered the streams and appeared in the
measurements there.  The underlined totals are probably the best to use.
1962
Phosphorus

Streams
Sewage plant effluent
Combined sewer overflow
Total
  Total P
   80,900
  128,300
   21,600
  230,800
This was the year of maximum sewage input but no measurements were made.
Diversion started in March 1963.  To obtain the figures listed, sewage
plant effluent was calculated by proportion with the populations served
by the  treatment plants in 1962 and 1964 (see below).  Combined sewer
overflow was estimated by proportion with the estimate of 1957 and the
sewage  plant effluent.  Septic tank drainage was ignored, since many of

                                 296

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Table 2.   (Continued)
the formerly unsewered areas were now sewered.   A sewage treatment
plant served the town of Bothell on the Sammamish River from 1959 to
March 1967, and the effluent went into the river where the nutrients
would appear in the stream analyses.  The population served by the
plant was 2,460 in 1962 and 2,600 in 1964.

1964
Phosphorus
                                   Total P
Streams                             80,900
Sewage plant effluent              103,900
Combined sewer overflow             17,500
Total                              202,308

Nitrogen
                               Total Organic N  Inorganic N      Sum
Streams                            380,500        527,000      907,500
Sewage plant effluent              271,000         33,000      304,000
Combined sewer overflow             45,700          5,600       51,300
Total                              697,200        565,600    1,262,800

Data from Municipality of Metropolitan Seattle.  By 1964, three of the
sewage treatment plants had been diverted.  In 1957 they had contributed
34.2% of the dissolved P and 33.2% of the total P.  However, the popula-
tion served by each plant had increased.  Combined sewer overflow was
calculated as for 1962.  Inorganic N means nitrate and nitrite.

1970-1974
Streams only

          Total P       Dissolved P*     Total Organic N   Nitrate-N
1970      43,700            	                	          442,600
1971      37,600            	              401,600        559,800
1972      91,200           21,240            647,800        719,900
1973      26,800           14,000            807,200        398,400
1974      41,300           16,700            386,900        453,300
1975      66,300            7,300            607,900        640,500
                       *Perchloric acid
                   digestion of filtered
                           sample

Sewage diversion started in 1963 and was finished early in 1968, although
most had been diverted by 1967.  Floods in the Cedar River in early 1972
and in winter 1975-1976 brought in much silt, accounting for the ele-
vated phosphorus input in those years.  The 1972 flood was accompanied
by more erosion and landslides than the later one.
                                   297

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Table 2.  (Continued)
B.   Loading
The values in Part A were used to calculate the annual loading figures.
The area of the lake is 87,615 thousand m , the volume is 2,853.0 million
        the mean depth 32.9 m.
tn3,

1957
1962
1964
1970
1971
1972
1973
1974
1975
Inflow
Thousands m-*
973,600
964,400
1,554,061
1,207,800
1,539,706
1,513,606
898,300
1,329,300
1,479,740
                        Total P
                       g/m2-year

                          1.2
                          2.6
                          2.3
                          0.5
                          0.43
                          1.0
                          0.31
                          0.47
                          0.76
                                     Dissolved P
                                      g/m^'year

                                         1.1
  Inflow
                                         0.24
                                         0.16
                                         0.19
                                         0.08
Lake Volume

   0.338
   0.334
   0.539
   0.419
   0.534
   0.525
   0.311
   0.461
   0.513
Hydraulic
loading
   11.
   11.
   17.
   13.8
   17.6
   17.3
   10.2
   15.2
   16.9
     All the values in this table involve a certain amount of estimation
and extrapolation since measurements of flow and concentration were not
made in all the small inlet streams each year.  There is more than one
way to approximate some of the values, as by proportion with watershed
area, by regression of one stream that has been gauged only part of the
time on one that has a complete record, or by hydrological calculation.
The most elaborate study of the small streams was made in 1957 by the
Seattle Engineering Department (Hollis M. Phillips, personal communica-
tion; see Edmondson 1972).  In 1957, 10 small permanent streams contri-
buted 8.8% of the water, 13.5% of the total phosphorus, 24.7% of the
phosphate, 30.3% of the nitrate, and 15.2% of the Kjeldahl nitrogen.
The chemical content of the small streams is more like that of the Sam-
mamish River than of the Cedar, and the following proportions of the
Sammamish input were used for calculating stream input for later years
when all the streams were not measured:  water 24.5%, total phosphorus
13.5%, phosphate 50.6%, nitrate 43.8%, Kjeldahl nitrogen 38.6%.  In 1957
the volume of sewage effluent was 8,608 thousand m , less than 1% of the
streamflow.  The maximum rainfall in the years listed was 104.5 cm in
1972, amounting to 91,557 thousand m-* on the lake, about 3% of the vol-
ume of the lake.  These volumes have been ignored in calculating inflow
which is limited to stream flow.

     The loading calculations for 1970-1974 do not include flow from
Seattle's storm sewers nor overflow from the remaining combined sewers
that occurs during rainy periods.  In 1976, this amounted to about
7,000 kg/year of total phosphorus, or 0.08 g/m^, about equally divided
between the two sources (personal communication, Glen Farris and John
Buffo of METRO).  The calculations also do not include overland drain-
age or inflow from temporary streams.

     Some of the differences between this table and previously pub-
lished values are accounted for by improvements in the information
available and in the calculations.  Some values in this table for years
after 1971 may be revised in future calculations as more information
becomes available, but any changes are expected to be small.  Phosphorus
and water loading for any year are unlikely to be increased by as much
as 20% over the values presented here.
                                    298

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                           References

     The following list gives sources of. information in addition
to the papers cited in the text.

Comita, G.W. and G.C. Anderson.  1959.  The seasonal development
     population of Diaptomus ashlandi Marsh, and related phyto-
     plankton cycles in Lake Washington.  Limnol. Oceanog.
     4.: 37-52.

Davis, M.B.  1973.  Pollen evidence of changing land use around
     the shores of Lake Washington.  Northwest Science.  47:133-148.

Edmondson, W.T.  1963.  Pacific Coast and Great Basin, p. 371-
     392.  In D. G. Frey  (ed.) Limnology in North America.
     University of Wisconsin Press, Madison, Wisconsin.

Edmondson, W.T.  1961.  Changes in Lake Washington  following an
     increase in the nutrient income.  Verh. Internat. Verein.
     Limnol.  14:167-175.

Edmondson, W.T.  1966.  Changes in the oxygen deficit  of Lake
     Washington.  Verh. Internal. Limnol. Verein.   16:153-158.

Edmondson, W.T.  1968.  Water quality management and lake
     eutrophication:  The Lake Washington Case.  Water Resouces
     Management and Public Policy,  pp. 139-178.  T.H. Campbell
     and R.O. Sylvester (eds.) University of Washington Press.

Edmondson, W.T.  1970.  Phosphorus, nitrogen and algae in Lake
     Washington after diversion of sewage.  Science 196:960-691.

Edmondson, W.T.  1972a.   Nutrients and phytoplankton in Lake
     Washington, pp. 172-193.  In Nutrients and Eutrophication,
     American Society of  Limnology and Oceanography, Special
     Symposia No. 1.  G.  Likens (ed.).

Edmondson, W.T.  1972b.   The present condition of Lake Washington.
     Verh. Internat. Verein. Limnol.  18:284-291.

Edmondson, W.T.  1973.  Lake Washington, pp. 281-298.  In
     Environmental Quality and Water Development.   Ed., C.R.
     Goldman, James McEvoy III and Peter J. Richerson.  Freeman.
     (Originally published as a report to the National Water
     Commission).

Edmondson, W.T.  1974a.   Review of The Environmental Phosphorus
     Handbook.  Limnol. Oceanog.  _19_:369-375.  (contains extensive
     comments on concepts of eutrophication).

Edmondson,  W.T.   1974b.   The sedimentary record of the eutrophication
     of Lake Washington.   Proc.  Nat.  Acad.  Sci.  71;  5093-5095.

                               299

-------
Edmondson, W.T.  1977.  The recovery of Lake Washington from eutrophication.
     pp. 102-109 in Recovery and restoration of damaged ecosystems., ed.
     John Cairns, Jr., K.L. Dickson and E.E. Herricks, Univ. Press of
     Virginia.

Edmondson, W.T. (in press).  Trophic equilibrium of Lake Washington.
     Final Report on E.P.A. Project R 8020 82-03-1, Corvallis, Oregon.
     (Contains description of chemical methods used).

Scheffer, V.B., and R.J. Robinson.  1939.  A limnological study of Lake
     Washington.  Ecol. Monogr. JJ: 95-143.

Shapiro, J., W.T. Edmondson and D.E. Allison.  1971.  Changes in chemical
     composition of sediments of Lake Washington, 1958-1970.  Limnol.
     Oceanog. 16: 437-452.

Thut, R.  1969.  A study of the profundal bottom fauna of Lake Washington.
     Ecol. Monogr. 39: 79-100.
                            ACKNOWLEDGEMENTS

     The main project on Lake Washington  reported here has been supported
 for many years by  the National  Science  Foundation,  supplemented in 1973-
 1976 by the Environmental Protection Agency.
                                  300

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                     NUTRIENT LOADING AND TROPHIC STATE

                       OF LAKE SAMMAMISH, WASHINGTON


                         E. B. Welch, T.  Wiederholm,

                       D. E. Spyridakis and C. A. Rock
                       Department of Civil Engineering
                          University of Washington
                            Seattle, Washington
                                INTRODUCTION
     Lake Sammamish is best characterized as mesotrophic and sediment core
analyses indicate that its status has remained relatively constant for more
than the past 100 years.  The lake has been studied continuously since late
1969 with only two previously recorded studies;  a nearly two-year study by
the Municipality of Metro Seattle in 1964-65 and a one day survey in 1913
(Kemmerer et al., 1924).  In addition to continuous monitoring of limnological
characteristics since late 1969 to the present,  special studies of secondary
production (zooplankton and fish), nutrient exchange rates between sediment
and water, phytoplankton uptake of nutrients, feeding rates of zooplankton,
profundal bottom fauna, and dynamic modeling of  the phosphorus cycle have con-
tinued, as well as a careful evaluation of the nutrient (particularly P) income.

     Most of this effort has been for the purpose of defining the processes
that have permitted the lake to remain mesotrophic in spite of alteration
of the P loading.  Because the lake was thought  to be showing early signs
of eutrophication (Isaac et al., 1969), the Municipality of Metropolitan
Seattle (Metro) diverted the secondary effluent  from the town of Issaquah
and waste from a dairy processing plant in the fall of 1968.  This diversion
was subsequently shown to have amounted to one-third of the lake's P loading.
The lake's internal sediment-water interchange mechanism controlled by iron
can resist P loading changes over a range of at  least 0.66-1.0 g P/m2 year.
This allows the available water column P content to remain remarkably stable
and is probably the main cause for the lake's lack of response to diversion.
However, stability could not be expected to persist over a much greater
range in loading and when viewed over the range of trophic state and loading
                                     301

-------
that exists in the world's lakes, the range examined in Sammamish appears

rather small.


                GEOGRAPHIC DESCRIPTION OF LAKE SAMMAMISH


     The waning of the Wisconsin glaciation (14,000 BP) left the Puget Sound

lowlands dominated by striated hills, rolling uplands, and deeply cut troughs.

Today one trough is occupied by Lake Sammamish, a second by Lake Washington

with the -meandering Sammamish River connecting the two.  A mild, maritime

climate now prevails, annually producing 90 centimeters of precipitation and

a mean monthly temperature of 11.5°C (52.7°F).  Direct sunshine is present

45 percent of the daylight hours.  Table I provides a summary of the pertinent

geographic conditions.



    Parameter                                        Lake Sammamish


Location
   Altitude (meters above mean sea level)                 12
   Longitude                                          122°05'W
   Latitude                                            46°36'N
                          o
Size of Drainage Basin (km )                             253
Duration of ice cover                                    none
Evapotranspiration (cm)                                   23.7
Evaporation (cm)                                           5.1
Precipitation (cm)                                        90
Maximum monthly precipitation (cm                         39
Minimum monthly precipitation (cm)                         0



Table I.  Summary of Basin Geography



     The predominant surface stratum of the drainage basin is a light-gray

till.  This till is a hard unsorted mixture about 46 meters thick, consisting

of clay, sand silt, and gravel.  Although the till is relatively impermeable,

thin beds of sand and gravel commonly yield small quantities of perched water.

                                  3Q2

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Aquifers transect the basin, with several artesian wells surfacing within the




basin (Liesch, et_ al., 1963).  Coal seams are located in the southern half




of the watershed, while high quality sand and gravel,'refractory grade clay,




quarry basalt and cinnebar deposits are scattered throughout the basin




(Livingston, 1971).




     A geologic cross-section cutting through Issaquah in an east-west




direction shows base rock consisting of marine sedimentary rocks on the west




side of the Lake Sammamish valley.  On the east side is volcanic rock with




overlying layers of clay, advanced stratified drift, till and sedimentary




deposits (Liesch, eit al. , 1963).




     Prior to the arrival of European settlers in 1862, the Lake Sammamish




basin was covered in a climax formation of Western Red Cedar (Thuja plicata),




Western Hemlock (Tsuga heterophylla), and Douglas Fir (Fseudotsuga taxifplia)




(Hansen,1938).  Heavy logging around the turn of the century left the basin




in second growth forest.  Today 80% of the watershed remains in second




growth, primarily red alder (Alnus oregona) with scattered maple (Acer, sp.)




and willow (Salix sp.).  Hence tjie impact of land erosion upon the lake is




minimized.




     The population of the basin has grown from three families in 1862 to the




present 40,000, the majority of the growth coming in the last 10 years.  The




only sizeable concentration is located in the town of Issaquah, population




4,500.  The town is comprised of the small businesses required to support a




residential community.  The only industrial development is a dairy processing




plant and a state salmon hatchery.  Within the watershed are several gravel




operations and a county sanitary landfill.  Large residential developments




have been built throughout the entire west side of the lake.  The east side




is dotted with small farms, but the mjaor portion of the land remains in




second-growth.  A narrow strip of land along the east shore of the lake has



                                   303

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been subdivided into residential tracts.  The upper valley drained by


Issaquah and Tibbetts Creeks is primarily forested with scattered farms


and small clusters of houses (Fig. 1).


     The primary point sources of wastewater within the basin were the town


of Issaquah, the milk processing plant, and the fish hatchery.  Since 1968,

                                                          3
the effluent from the town's trickling filter plant (568 m /d) and the milk


plant (284 m /d) have been diverted out of the basin.  Today only the milk

                          o
plant cooling water (227 m /d from groundwater) and the hatchery passthrough


water, which originally comes from Issaquah Creek, are discharged through


Issaquah Creek, to Lake Sammamish.  Only the sparsely settled east side and


upper valley sections of the watershed remain on septic tanks.



       MORPHOMETRIC AND HYDROLOGIC DESCRIPTION OF LAKE SAMMAMISH



     Lake Sammamish occupied a 13 km section of the Sammamish River Valley


after the Wisconsin glaciation when the retreating Vashon glacier left a


terminal maraine blocking the valley.  Today the lake level is controlled


by a weir at the head of the Sammamish River.  Morphometric and hydrologic


data on the lake are summarized in Table II.  Sixty five percent of the lake


surface has a depth greater than 15 m.  The ratio of epilimnion to


hypolimnion volume is 1.0.


     The preliminary mapping of surface lake sediments completed to date


include particle size distribution and mineralogical  composition, cation


exchange capacity and chemical analysis shown below  (Horton, 1972):


Properties	    Mean Value	Properties	       Mean Value
CEC, meq/lOOg
Size distribution, %
Sand
Silt
Clay



23.9
13
60
27



Chemical Analysis,
C
N
P
Fe
Mn
Ca
Mg
Na
K
mg/g dry weight
5.1
4.8
1.3
52.0
1.1
8.1
15.7
21.2
2.9
                                   304

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                          'X    Figure 1.  Land Use Map of the Lake

                           V            Sammamish Watershed
                            >
                            (
                            v.- —.
                            -LAKE SAMMAMISH
Phantom —TT=
                                      Beaver Lake /
Lake ^ZS
                 Tibbetts
                 Creek
   Drainage
   Boundary
                                      East Fork
                                      Issaquah
                                      Creek
        kilometers
                                     Issaquah
                                     Creek
 :;;:;  INDUSTRIAL
     COMMERCIAL
     RESIDENTIAL
                                                                N
                                                                A
                               305

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   Parameter                               Lake Sammamish


 Drainage Area (km2)                            253
 Surface Area of lake (km2)                      19.8
 Lake Volume (km3)*                               0.35
 Depth
    Mean (m)                                     17,7
    Maximum (m)                                  32.0
    Epilimnion (m)                                8.8
    Euphotic (m)                                  7.3
 Width
    Mean (km)                                     1.5
    Maximum (km)                                  2.4
 Length of Lake (km)                             13.0
 Length of Shoreline (km)                        34.0
 Water Retention Time (yrs)                       2.2
 Stream Inflow (knr/yr)                           0,167
 Stream Outflow (km3/yr)                          0.162
 Groundwater Infiltration  (km3/yr)                0.0
 Groundwater Exfiltration  (km3/yr)                0.01
 Duration of Stratification (mos)                 7

          *influenced by wier
Table  II.  Summary of Pertinent Rydrologic and Morphometric
            Characteristics for Lake Sammaroish
     The study of water currents has been limited to the movement of Issaquah

Creek water in the lake (Moon, 1973).  During the period of winter mixing the

creek water dispersal was primarily influenced by wind direction and velocity.

The water was sufficiently dispersed at a distance of 500 m to make the tracer

undetectable.  Similar studies made during thermal stratification showed the

creek water plunging into the metalimnion (9-12 m) and dispersing in a fan-

like pattern.
                                  306

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                     LIMNOLOGICAL CHARACTERIZATION






     The limnological monitoring of Lake Saramamish has been continuous since




1970.  Prior to 1970, Metro monitored the lake for a 1.5 year period in 1964




and 1965.  Monitoring has been conducted largely at one centrally located




station which has been shown to represent the limnetic area, and at a




frequency of usually twice per month.






                                Physical




Temperature




     The lake is monomictic and begins thermal stratification in May.  Maximum




water column stability occurs by late August and destruction of the thermocline




is complete by late November.  The surface temperature range is from a




minimum 5.5°C to a maximum 25.5°C.  The bottom water remains below 7°C.






Light Penetration




     The depth of visibility has been determined by means of the Secchi disc.




The annual mean for the six years of data is 3.3 m.  The lowest seasonal




readings (3.0 m) occur in the winter due to turbidity from the winter mixing




and runoff.  The springtime mean is only slightly higher (3.1 m), but the




low values are due to the diatom pulse.  The light penetration increases




during the summer (3.5 m) and reaches its highest mean value in autumn




(3.6 m).




     Light extinction was determined by a submarine photometer.  The bottom




of the euphotic zone was considered to be at a depth receiving 1% of the




surface light intensity.  The mean depth of the euphotic zone is 7.3 m,




while the range is from 5.0 to 12.5 m.






                                  307

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Solar Radiation



     Insolation was determined at the University of Washington campus with an


                                                                           2

integrating Epply pyranometer.  The ten year mean insolation is 3000 kcal/m /


                               2                               2
day and the range is 700 kcal/m /day in December to 5700 kcal/m /day in August.
                                Chemical




pH and Alkalinity



     The pH ranges from 6.3 to 9.6 due largely to biological activity.




Correspondingly the alkalinity as CaCO- ranges from 26 mg/1 (0.52 meq/1)




to 42 mg/1 (0.84 meq/1), while the mean is 33.3 mg/1 (0.67 meq/1).
Dissolved Oxygen



     During the winter, the oxygen content essentially remains at an air



saturation level, approximately 12 mg 0^/1, due to continual circulation.



The development of thermal stratification in early May results in a clino-




grade Q  curve that approaches zero oxygen content (0.1 mg 0/1) in the




bottom waters by mid-August.  The hypolimnetic oxygen deficit continues to



increase until early October.  By this time the entire hypolimnion (below



15 meters) has less than 1 mg 0/1.  Oxygen levels start to increase with



the coming of the autumnal circulation.






Phosphorus



     Total and ortho-phosphorus have been measured from 1969 to the




present.  The five-year mean concentrations for the 7.3 m photic zone are



as follows:
Total-P  (yg/1)




Soluble  ortho-P  (yg/1)
yearly
26
6
3Q8
winter
(Dec . -Feb . )
30
13

growinj
(March-
25
4


-------
The winter total P content in 1975 remained identical to the previous five-

year mean - 30 yg/1.  The winter mean total phosphorus concentration for the

entire water column was 36 yg/1.  This reflects the higher total phosphorus

concentrations found in the hypolimnion.  The mean total P content in the

water column prior to fall turnover is greater - 40 yg/1.  The range in total

and ortho P over the five years has been 10-90 and 1-21 yg/1, respectively.


Nitrogen

     Although all forms of N have been determined for only the past year,

inorganic nitrogen (NO-+NO.-N) data are available for the past five years.

The five year annual mean for the photic zone is 180 yg N/l and 275 yg/1

for the growing season (March-Aug.).

     Annual surface water values have been computed for calendar year 1973

and are summarized below:

                         Mean Annual                 Range
             	Concentration (yg N/l)	(yg N/l)
              Organic N       225                    60 - 403
              NH3-N            41                     5 - 125
     The 1973 inorganic nitrogen (NO^+NO -N) mean compares favorably with

the four year photic zone mean (191 vs 180 yg N/l), indicating that the

single year's data may be representative of the long-term nitrogen

concentrations.


Metals

     Only preliminary data are available for metals.  Neither SO,  nor Cl
                                                                     I i
have been measured, while the only trace metals measured have been Mn  ,
  i [       i i
Zn   and Pb  .  The results from a single central station survey during

the  stratified period are shown as follows:

                                  309

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location
Lake Surface
Surface
8 m
16 m
25 m
Inflows
Issaquah Ck.
Tibbetts Ck.
Outflow
Sammamish
River


Ca

12.80

8.40
8.95

12.40
24.70

6.05


Mg

3.42

3.44
3.68

3.70
8.15

3.00
cr/1
g/J-
Na

8.43
8.47
8.15
8.17

9.31
14.59

8.16


K

1.01
0.98
0.94
1.00

0.94
1.52

1.13


Fe

40
63
280
1020

450
110

25
IIS*/
yg/
Mn

19
40
600
1660

35
20

9

	
Zn

376
300
35
34

318
150

7


Pb

0.5
0.5
0.8
0.8

0.9
4.2

0.6
                              Biological


Phytoplankton


     Phytoplankton has a peak in the spring composed primarily of diatoms.


The dominating genera during winter and spring are Melosira and Stephanodiscus.


During the summer and fall, Fragilaria, Synedra, Melosira, Rhizosalenia and


Asterionella are the major diatoms.  The bluegreen algae are comprised pre-


dominantly of Aphanocapsa, Microcystis, Coelosphaerium, Anabaena and


Aphanizomenon.  In 1973-74 the appearance of Aphanizomenon has been less


pronounced than earlier while the abundance of an Oscillatoriaceae species


has increased.  Predominant chlorophyseans are Oocystis, Sphaerocystis,


Closteriopsis, Chlamydomonas and Staurastrum.  Also predominant in the


phytoplankton of the lake is the chrysomonad Mallomonas.


     Mean values for phytoplankton chlorophyll a. and primary productivity


are given in Table III.   Peak values during the years 1970-74 were 25.1,


28.3, 7.7, 12.2 and 13.9 mg/m3 for chlorophyll a_ and 1257, 1061, 1730,

                    2
1581 and 2389 mg C/m -day for primary productivity, respectively.  The blue-


green algae have decreased in importance over the 1970-74 period compared


to the pre-sewage-diversion period in 1964-65.  The average decrease has


been nearly 40%.

-------
Year
1970
1971
1972
1973
1974
Average
Chlorophyll a_
(mg/m3)
yearly growing season
5.
6.
4.
4.
6.
5.
7
6
3
0
0
3
7.7
10.9
4.8
4.7
6.8
7.0
Primary
(mg C/m
yearly
711
467
799
496
789
652
Productivity
2 -day)
growing season
899
575
952
545
904
775
Table III.  Annual and growing season means of phytoplankton chlorophyll a_
             (weighted means for the euphotic zone) and daily rate of primary
            productivity in 1970-1974.
Zooplankton

     Vertical net hauls was the procedure used to collect zooplankton at

frequencies varying from twice weekly to once per month with the least fre-

quency at periods of low reproductive activity.  The zooplankton fauna were

dominated in 1972-73 by copepods, among which Diaptomus ashlandi was the most

abundant species.  The following species of zooplankton have been found

Vindicates common species) :
Copepods
 *Diaptomus ashlandi
 *Epis chura nevadensis
 * Cyclops bi cuspi datus

Cladocerans
 *Daphnia thorata
 *D.
        _
 *Bos_mina longer ostris
 *Diaphanasoma leuch tenb er gianum
  Leptodora kindtii
  Scapholeberis king!
Rotifers
 *Kellicottia longispina
  BC. bos ton ien sis
 *Polyarthra sp.
  Keratella cochlearis
  K^. quadrat a
 *Conochilus unicornis
  Collotheca mutabilis
  CL.' pelagic a
  Notholca squamula
  Ploesoma hudsoni
  Gastropus sp.
  Synchaeta sp.
  Trichocerca sp.
  Filinia sp.
                                   311

-------
     The mean biomass and production rate of zooplankton in the lake during

the two-year period 1972-73 was:

                                        annual mean	growing season
3
Biomass (mg/m dry wt.)
Production rate
(mg/m-Vday dry wt.)
44.3

.98
46.1

1.26
The growing season secondary productivity was only 4% of the primary produc-

tivity.  Discussion of this low efficiency is given by Pederson, et al.

(in press).


Bottom Fauna

     A survey of the bottom fauna was made in July 1974.  The macro fauna was

dominated by chironomids in sublittoral (5 m) and deep profundal areas (25 m).

Oligochaetes were dominating in the upper profundal (15 m) (Table IV).

Cladotanytarsus and Tanytarsus were the dominating chironomid genera at 5 m

depth.  Chironomus larvae of the salinarius type (probably identical with

Ch. atritibia),  followed by Phaenop sectra were the most abundant forms at

15 m.  The high density of Chironomus at 25 m depth was almost exclusively

larvae of the Ch. salinarius type.  The growth and development of this

species is closely correlated with phytoplankton production and the duration

of anoxic conditions in the deep profundal (Bissonnette, 1974).
                              5m             15 m            25 m
 	(7 Ekmans)	(10 Ekmans)	(8 Ekmans)

 Chironomidae                8330            3040            22640
 Ollgochaeta                 1870            7010             4960
 Mollusca                     310             270               40
 Crustacea                     10              60
 Others                        50
Table IV.  Abundance of major groups in the bottom fauna in July 1974
           (ind/m ; 0.4 mm mesh size)

                                   312

-------
Bottom Flora and Macrophytes

     Meager data exist on this topic.  The littoral zone is not extensive

in the lake but moderate sized areas of submergent macrophytes do occur at

either end of the lake.  Periphyton growth occurs at some points adjacent

to stream or storm water inflows, which is a topic presently under study.



                            NUTRIENT LOADING

Phosphorus

     Earlier estimates of the nutrient loading to Lake Sammamish were made

difficult by the quick response to rainfall in the tributaries, particularly

Issaquah Creek, which contributes 70% of the surface water and 72.5% of the

total phosphorus to the lake (Emery, et_ jil^. , 1973).  For example, as much as

5% of the total annual phosphorus load has been calculated to enter the lake

in one day due to a combination of high flow and high nutrient concentrations,

The installment of an automatic sampler in the main tributary in 1973 has

permitted accurate estimates of phosphorus loading for the last two years.

Through comparison of similar hydrological years and the results of earlier

monthly samples, the decrease in loading through sewage diversion was

estimated.  Limited rainwater analyses during water year 1971 established an

atmospheric input to the lake surface.  Groundwater input was considered

insignificant relative to the other sources because the water balance was

roughly explainable from a consideration of surface inputs and outputs.  The

loading rate of phosphorus from three sources is shown below:
Percentage
Source

Waste Discharges
Land Runoff
Precipitation
Groundwater
before
div.
37
58
5
0
after
div.
3
89
8
0
kg P/yr
before
div.
7,500
11,500
1,000
0
after
div.
500
11,500
1,000
0
       Total              100               20,000     13,000
                                   313

-------
Nitrogen


     The data for a nitrogen loading are not as extensive as for phosphorus.


The contribution from ground water has been assumed to be zero, while the


contribution from precipitation has not been evaluated.  On the basis of


the following estimates before and after sewage diversion in 1968 there


appears to be no significant change in nitrogen loading (Guttormsen, 1974):


                            Organic N+NH--N    NO +NO--N     Total N
                                 -  /    O        £,   J         ,   I
*~*'yL kg/yr ^'yL
1965 Water Year
March 1972-Feb. 1973
69,000
60,000
174,000
198,000
243,000
258,000
                               DISCUSSION



                      Limnological Characteristics


     The outstanding characteristic in Lake Sammamish is its consistently

                                            2
high oxygen deficit rate of about 0.05 mg/cm 'day and complete hypolimnetic


anaerobiosis from August through October.  This is caused more from the


lake's morphometry than high productivity since the epilimnion-to-hypolimnion


volume ratio is rather high at 1.0 and the growing season mean productivity

                        2
is only about 700 mg C/m "day, which is more typical of mesotrophy.  Iron


and phosphorus content are inversely related to oxygen content in the


hypolitnnion and, thus, the process of phosphorus release and complexation


and resultant availability is controlled by the lake's anaerobic character.


Because the lake is monomictic a winter stagnation period does not exist.


     The lake usually has one large phytoplankton maximum - a diatom out-


burst in April.  In springs with lower light and slower onset of water


column stability the maximum is less, is delayed until June and is mixed

                                  314

-------
with green and bluegreen algae.  However, mean growing season chl ji content

and productivity show much less variance from year-to-year ranging from
                                2
4.7-10.9 yg/1 and 545-952 mg C/m -day, respectively.  Secchi disk depth is

similar from year-to-year, with a growing season mean slightly in excess

of 3.3 m and the maximum exceeding 5 m at times.

     The minimum nutrient content and chl a_ occur in August, but usually

show a slight increase in September and October as the metalimnion is forced

downward proceeding toward the November turnover.  Total P is then maximum

at overturn reaching 40 yg/1 (in excess of 100 before sewage diversion), with

the December through February mean remaining very constant at about 30 yg/1.

Nitrate-N at this time is typically around 275 yg/1.

                             Trophic State

     The present trophic state of the lake was determined by a comparison

of the above mentioned limnological characteristics with criteria for

eutrophication (National Academy of Sciences, 1972).  It appears that Lake

Sammamish can be considered as mesotrophic with respect to phytoplankton

biomass (expressed as chlorophyll a), daily and annual primary productivity

and the composition of the benthic communities.  Oxygen deficit rate and
nutrient concentrations are more indicative of mesotrophy-eutrophy.  The
                                     2                               2
loading of total phosphorus (0.66 g/m -yr) and total nitrogen (13 g/m -yr)

are both considerably above the eutrophic danger limit of Vollenweider's

(1968)  guidelines.  With his recent correction of mean depth for flushing

time the loading rates are nearer the danger limit, however.

     Paleolimnological studies of diatom profiles, phosphorus and organic

content, and distribution of chironomid head capsules show no change in

the trophic state of the lake during the last 120 years.
                                   315

-------
                   Trophic State vs. Nutrient Loading


     The fact that both producers and consumers in the lake do not seem to


respond to the eutrophic level of nutrient loading suggests that some internal


factor(s) is controlling the availability of the incoming phosphorus to the


phytoplankton (Welch, &t_ a^., 1973).  The evidence to support the hypothesis


centers around the lake phosphorus content being controlled by iron.  Horton


(1972) has shown that total iron is closely correlated with total phosphorus


as oxygen is exhausted in the hypolimnion during late summer.  Although


phosphorus increases in the surface waters following lake turnover in late


November, P is rapidly complexed by what are probably ferric hydroxides.


Much of the released phosphorus is thereby largely resedimented and rendered


unavailable to the phytoplankton when light is adequate in April and May.


     The pattern of response in the lake since diversion is shown in Fig. 2.


Although considerable year-to-year variation has occurred in chl a. content,


the photic zone total P content has remained rather constant.  The year-to-


year variation in chl a_ observed was no doubt largely a response to light and


extent of early spring stratification, but the constant P content is indica-


tive of the lake's resistance to P loading change in the range of at least

                 o
0.66 to 1.0 g P/m 'yr.   However, when viewed over a wider range of loading


known for lakes of varied trophic state its general significance is question-


able.  Fig. 3 shows a very strong correlation between volumetric P loading


and "potential" chl a. (chl a. r residence time - yr) .   Here one can see the


controlling significance of P loading with respect to chl a_ accumulation


(in so far as water residence time allows P utilization) over a wide range


of loading.  Also, the relatively small aberration in chl a_ that could be


caused by the observed P loading change in Lake Sammamish is clear.  With


further loading change Sammamish might well be expected to conform to the


linear relationship in Fig. 3.

                                  316

-------
          150
      CO
      cu
     m
     v£>
      C
      o
     •l-l
      CO
     •H
     T3
      (1)
      t-l
     p-l
      d
      0)
      o
      )-l
      OJ
          125
          100
Figure 2.
 75
           50
           25
            0
                 Waste

                 Water

                 Diversion

                	i
                                 % Blue Green Algae
                                 Fraction         \

                                                     \
                                                       V
            65       70        71       72     73     74

                                 Year

Mean concentrations in  the  photic  zone  (usually top 8 m) of growing

season chl a_ (Mar-Aug), summer  blue green algal fraction (June-Oct)

and winter (Dec-Feb)  total  phosphorus and nitrate nitrogen relative

to pre-diversion 1965 levels.   The 1965 levels were: chl a. 6.5 yg/1

(actually a mean of 1964  and 1965  data), total P 31 yg/1 and

N03-N 390 yg/1.
                                     317

-------
       500
CO
LU
I-
O
CL
    O>
    6
    
P •'
   
-------
                            Acknowledgements

      This project was supported in part by EPA research grant No.  R-800512
 and in part by the National Science Foundation grant No.  GB-36810X to the
 Coniferous Forest Biome, Ecosystem Analysis Studies, US/IBP.   This is
 contribution No.  110 from Coniferous Forest Biome.
                               References
Bissonnette, P.  1974.  Extent of mercury and lead uptake from lake sediments
     by Chironomidae.   M. S. Thesis, Univ. of Wash.
Emery, R. M., C. E. Moon and E. B. Welch.  1973.  Enriching effect of urban
     runoff on the productivity of a mesotrophic lake.  Water Research, 7:
     1505-1516.
Guttormsen, S.  1974.   A nitrogen budget for Lake Sammamish, Washington.
     M. S. Thesis, Univ. of Wash.
Hansen, H.  1938.  Postglacial forest succession and climate in the Puget
     Sound Region.  Ecology 19;528-542.

Horton, M.  1972.  The chemistry of P in Lake Sammamish.  M. S. Thesis,
     Univ. of Wash.
Isaac, G. W., R. I. Matsuda, and J. R. Walker.  1966.  A limnological
     investigation of water quality conditions  in Lake Sammamish.  Water
     Quality Series No. 2.  Metro, Seattle, Wa.
Kemmerer, G., J. Bovard, and W. Boorman.  1924.  Northwestern lakes of the
     U.S.:  Biological and chemical studies with reference to possibilities
     in production of fish.  Bull.  U.S. Bur. Fish., 39;51-140.
Liesch, Price and Walters.  1963.  Geology and  groundwater resources of
     northwest King County, Wash. Water Supply  Bull. No. 20, USGS.
                                  319

-------
Livingston, Jr., V.  1971.  Geology and mineral resources of King County,




     Wash. Wash. Dept. of Nat. Res. Bull, No. 63.




Moon, C. E.  1973.  Nutrient budget following waste diversion from a




     mesotrophic lake.  M. S. Thesis. Univ. of Wash.




National Academy of Sciences.  1972.  Water Quality Criteria 1972, Aesthetics




     and Recreation Section, Wash. D. C.





Pederson, G. L., E. B.  Welch and A. R. Litt.   Plankton secondary productivity




     and biomass; their relation to lake trophic state.  Hydrobiologia (in




     press).




Vollenweider, R. A., 1968.  The scientific basis of lake and stream




     eutrophication, with particular reference to phosphorus and nitrogen




     as eutrophication factors.  Tech. Rep. OECD, Paris.  DAS/CSI/68,




     27:1-182.




Welch, E. B., C. A. Rock, and J.  D. Krull.  1973.  Long-term lake recovery




     related to available phosphorus.   Proceedings of Workshop on Modeling




     the Eutrophication Process.   Utah Water Resources Lab., PRWG 136-1,




     pp. 5-13.




Welch, E. B., G. R. Hendrey, and R. K. Stoll.  1975.  Nutrient supply and




     the production and biomass of algae in four Washington lakes.  Oikos.




     26:47-54.
                                   320

-------
                          SECTION VII - WISCONSIN


                       LAKE MENDOTA - NUTRIENT LOADS

                          AND BIOLOGICAL RESPONSE


                       Jose M. Lopez and G. Fred Lee
                    Institute for Environmental Sciences
                        University of Texas at Dallas
                             Richardson, Texas
                                INTRODUCTION
     Lake Mendota is the largest of the Madison lakes which form a chain along
the Yahara River in south-central Wisconsin.  It is classified as a hard-water,
eutrophic lake according to most standards.  The drainage area of Lake Mendota
is composed mostly of fertile farm land and the urban area.  The hypolimnetic
waters become devoid of oxygen during summer stratification.  After fall reox-
ygenation, oxygen depletion again occurs in the bottom waters during late win-
ter.  Excessive weed growth and periodic algal blooms create offensive condi-
tions during the summer months.
                           GEOGRAPHIC DESCRIPTION

     Lake Mendota is located in Madison, Wisconsin, the latitude and longitude
of the centroid of the water area being 43°7' N and 89°25' W.  The surface of
the lake stands at an altitude of 849 feet above sea level (Cline, 1965).  The
lake has a cumulative drainage area of 265 sq. miles (Lee, 1962).  The climate
of the basin is typically continental, the summers are hot and the winters are
cold.  The average annual temperature at Madison is 46.2°F and ranges from an
average 72.7°F in July.  During each of four winter months, December through
March, the mean monthly temperature is below 32°F.  The growing season extends
generally from late April to mid-October and averages 175 days (Cline, 1965).

     From 1852-1948, Lake Mendota showed an ice cover duration of 112 days
(14 December to 4 April) on the average.  Duration of ice cover ranged from
65 days in the winter of 1931-32 to 161 days in 1880-81.  The earliest the lake
has frozen over is 25 November 1857, and the latest it has thawed is 6 May 1957
(Frey, 1963).


                                     321

-------
         The precipitation varies widely during the year.  The
    maximum average monthly precipitation occurs in June, and
    the minimum average precipitation occurs in February.
    Generally 3 to 4 inches of precipitation per month occurs
    during May through September.  Most of this precipitation
    is associated with thunderstorms.  Between one and two
    inches of precipitation per month generally occurs during
    November through February.  The total yearly precipitation
    averages 31.2 inches, which includes an average annual
    snowfall of 37.8 inches or about seven inches precipita-
    tion.  The evapotranspiration rate from that part of the
    Yahara River basin covered by lakes and marshes is about
    equal to the precipitation (Cline, 1965) .

        Figure 1 is a schematic diagram of Lake Mendota
    showing depth contours and direction of the prevailing
    winds in summer.  The maximum fetch is about 9 Km and
    occurs when the wind is out of the southwest.
                             INLET
LAKE MENDOTA
  WISCONSIN
                                                         OUTLET
                             DEPTH CONTOURS IN METERS
Figure l. LAKE MENDOTA, WISCONSIN, SHOWING BATHYMETRY
                              322

-------
     Lake Mendota occupies a pre-glacial valley  system
excavated by  streams  in  sandstones  and  sandy dolomites of
upper Cambrian  age.   The lake was formed as a  result of
moranic damming during the most  recent  ice age (Twenhofel,
1933).  Rocks of Cambrian age, principally sandstone and
dolomite, were  deposited in shallow seas on a  surface of
igneous and metamorphic  rocks of Precambrian age.   Dolo-
mite and sandstone of Ordovician age were deposited on the
Cambrian rocks.  Glacial drift and  loess overlie these
formations  (Cline, 1965).

     Approximately 200,000 people live  in Madison  on the
southeast shore of Lake  Mendota.  Land  usage estimates
for the Mendota basin provided by Sonzogni and Lee (1974)
are shown in  Table 1.  A large area of  the drainage basin
is predominantly agricultural  (dairy farms and mixed
crops).
Table  1.  ESTIMATE  OF  LAND  USE WITHIN  THE  LAKE MENDOTA
          WATERSHED*

       Land  Use          Acres           Percent

       Rural            115,000            83
       Urban            16,000            12
       Marshland          6,000             4
       Woodland           1,000          	1
              Total     138,000          100
 *After  Sonzogni  and  Lee  (1974)
     Lake Mendota water is mainly used  for  sports, fishing
and recreation.  A  limited amount of lake water is pumped
into the University of Wisconsin water  supply system.  The
municipal supply for the City of Madison comes almost
entirely from ground water.

     In 1958, discharges of treated sewage  effluent were
diverted around all Madison lakes.  By  1973, waste water
from several small communities was diverted from Lake
Mendota tributaries  (Sonzogni and Lee,  1974) .
MORPHOMETRIC AND HYDROLOGIC DESCRIPTION

     Lake Mendota has a surface area of 15.2 square miles
(39.4Km2), a length of 5.9 miles  (9.5Km) and a width of
4.6 miles (7.4Km).  The shoreline is 20 miles  (32.2Km)
long.  The water volume is approximately 128 x 10^ gallons
(486 x 106m3).  Maximum depth of the lake is 84 feet  (25m)
while the mean depth is 40 feet (12m)  (Cline, 1965).
Depths greater than 12m occur in about 50 percent of the
surface area.  Details of the hypsometry of the lake are
given in Table 2.  The stratification period in Lake

                           323

-------
   Mendota may extend from May to October.   The volume ratio
   of epilimnion over hypolimnion varied from 0.93 in June
   to 5.34 in October, 1971.   This ratio was 2.66 during
   August, the time of maximum stability (Stauffer md Lee, 1973).
       Table 2.   HYPSOMETRIC FACTORS FOR LAKE MENDOTA
          SURFACE AREA OF LAKE MENDOTA 39.4 x 10^ m2
 Depth           Average % of Surface      Volume Contained
 Meters          Area Within Interval      Within Interval x
 	1Q-7 m3	

 0   - 0.5               98                     1.88
 0.5 - 1.5               92                     3.60
 1.5 - 2.5               87                     3.40
 2.5 - 3.5               82                     3.20
 3.5 - 4.5               77.5                   3.03
 4.5 - 5.5               73.5                   2.87
 5.5 - 6.5               71                     2.78
 6.5 - 7.5               69                     2.70
 7.5 - 8.5               66.5                   2.60
 8.5 - 9.5               64                     2.50
 9.5 -10.5               61.5                   2.40
10.5 -11.5               58                     2.27
11.5 -12.5               54                     2.11
12.5 -13.5               51                     1.99
13.5 -14.5               47                     1.84
14.5 -15.5               45                     1.76
15.5 -16.5               42                     1.64
16.5 -17.5               39                     1.52
17.5 -18.5               35                     1.37
18.5 -19.5               29                     1.13
19.5 -20.5               22                     0.86
20.5 -21.5               15                     0.59
21.5 -22.5                9                     0.35
22.5 -23.5                4                     0.16
23.5 -24.5                0.2                   0.01
                                           48.6 x 107m3
        The hydraulic residence time for the lake is 4.5
   years (Sonzogni and Lee, 1974).  A water balance of Lake
   Mendota for October 1, 1948 to October 1, 1949, is given
   in Table 3.

        Abrupt sedimentation changes have occurred in Lake
   Mendota in the recent past.  Buff marl is overlain by
   black gyttja, gray-colored gyttja-marl forms the inter-
   face between buff marl and balck gyttja.  The marl and
   gyttja differ in being high carbonate-low clastic and low
   carbonate-high clastic sediments, respectively.

                              324

-------
         Table 3.  WATER BALANCE OF LAKE MENDOTA,
            1 OCTOBER 1948 TO 1 OCTOBER 1949*
INFLOW
     a) Measured tributaries — Stations 1-10        78.4 cfs
        (192.27 mi2 of drainage basin)     2
     b) Unmeasured tributary area (31.87 mi
        of drainage basin, by computation)           13.0 cfs
     c) Precipitation onto lake surface
        (31.65 in.)                                  38.7 cfs

     Total Inflow (4,100,000,000 ft3)
OUTFLOW

     a) Storage                                       3.5 cfs
     b) Evaporation
        (51.17 in., by computation)                  58.2 cfs
     c) Outflow, Station 11                          70.0 cfs
     d) University pumpage                            1.5 cfs

     Total Outflow (4,200,000,000 ft3)              133.2 cfs

Unaccounted for:    133.2-130.0 = 3.1 cfs

     = 2.33 % of outflow
*After Rohlich, in Frey (1963)

       The  change  in  sedimentation  is  ascribed  to  increased
 deposition of  clastic material  in the  lake  as a  conse-
 quence of farm and  domestic  practices  (Murray, 1956).
 Cores of  Lake  Mendota show increased deposition  of  P, Fe,
 K,  and Organic-C while carbonate-C has decreased in most
 recent periods (Bortleson and Lee, 1972) .
  CURRENTS

      Bryson  and  Ragotzkie  (1955)  found  that  University  Bay
  (Lake Mendota) was normally occupied by a  clockwise  gyre,
  the  rotation rate of which is nearly constant  (period=0.5
  pendulum day)  and independent of  the current volocity.   A
  jet  of particularly high velocity extends  out  into the  lake
  along the  side of Picnic Point peninsula.  Clarke and
  Bryson  (1959)  found that, following diminution of stress
  from the surface wind,  a countercurrent rapidly develops
  below the  surface as observed at  Second Point  Bar.   Shulman
  and  Bryson (1961) found that wind driven currents deviate
  to the right of  the wind in a pattern which  fits the loga-
  rithmic spiral hodograph of classical theory.   Density

                            325

-------
currents were observed by Bryson and Suomi  (1952) in Lake
Mendota.  Turbid runoff following periods of rain either
flows along the bottom and spreads at the thermocline or
moves deep into the hypolimnion as dictated by density
relations.
LIMNOLOGICAL CHARACTERIZATION

     In Lake Mendota the temperature of the water ranges
from 0°C to 27°C.  Specific conductance varies from 250 to
350 umhos/cm at 20°C.  True color of the lake water is
from 5 to 15 mg/1 chloroplatinate.  During the summer
months very little light penetrates below 4-6m.  Turbidity
caused by the biomass acts to absorb and scatter incident
light.  On May 13, 1971, light penetrated all the way to
the bottom of Lake Mendota and 21 percent of the surface
light reached 4m.  Light continued to reach the bottom
until mid-June and after July 14, 1971, less than 4 percent
of the surface light reached 4m  (Torrey, 1972).

     Table 4 presents a typical chemical analysis of Lake
Mendota, giving the range of value of the most important
parameters of water quality (Lee, 1966).

     Algal populations of Lake Mendota include the bloom-
forming Microcystis, Oscillatoria, and Lyngbya.  In addi-
tion, the acetylene-reducing genera Anabaena, Aphanizo-
menon, Nostoc, Calothrix, and Gloeotrichia are commonly
observed (Torrey, 1972).  Typical blue-green algae counts
for the summer are on the order of 10  cells/liter.  Total
lake chlorophyll during the summer months averages 5,OOOKg,
with maximum values reaching 8,OOOKg of chlorophyll.  The
average and maximum chlorophyll concentrations per unit
area for the lake are 125 mg/m  and 200 mg/m , respec-
tively (Stauffer and Lee, 1973).   Primary production,
calculated from light intensity and chlorophyll data2
(Ryther and Yentsch, 1957), is on the order of 4gC/m /day
during the summer.

     Table 5 summarizes identities and counts of common
summer zooplankters in Lake Mendota.   These include
species of Daphnia, Cyclops, Copepods, Diaptomus, Chydorus,
Lecane and Asplanchna (Frey, 1963).

     Fish populations in Lake Mendota have changed since
the turn of the century.  Two major changes that have
been found are the decrease in number and increase in
average size of perch.  Cisco, once a very abundant fish
in Lake Mendota, has almost reached extinction; only rare
occurrences have been reported in recent years.  The dis-
appearance of Cisco from Lake Mendota has been attributed
to increase fertility of the lake.  Conway (1972) has
shown that the rate of dissolved oxygen depletion in
the hypolimnetic waters of Lake Mendota has increased
significantly from the early 1900's to the present.  Since
                            326

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         Table  4.   TYPICAL ANALYSIS  OF  LAKE  MENDOTA,
                         1965-1966

 Based  on a  1.5  Year  Study by  Students  and Staff  of Water
 Chemistry Program, University of Wisconsin-Madison*
 Water
Range**
 Temperature  C
 Specific  Conductance  umhos/cm at  20  C
 pH
 Turbidity ppm  SiC>2
 Color  (true) chloroplatinate  mg/1
 Sodium mg/1
 Potassium mg/1
 Magnesium mg/1
 Calcium mg/1
 Nitrate mg N/l
 Nitrite mg N/l
 Ammonia mg N/l
 Organic mg N/l
 Total  Phosphate mg/P/1
 Orthophosphate mg/P/1
 Dissolved Solids mg/1
 Filterable Solids mg/1
 Silicon Dioxide mgSi02/l
 Chloride  mg/1
 Iron mg/1
 Manganese mg/1
 Dissolved Oxygen mg/1
 Chemical  Oxygen Demand mg/1
 Dissolved Organic Carbon  mg/1
 Flouride  mg/1
 Alkalinity total mg/1 of  CaCO-
 Sulfate mg/1
0-27
250 - 350
6.5 - 9.2
10 - 50
5-15
4.5 - 8.0
3.5 - 4.0
23 - 28
26 - 30
0 - 0.7
0.0025 - 0.02
0.04 - 0.9
0.5 - 5.0
0.05 - 0.65
0.02 - 0.4
200 ± 20
10 - 60
0.1 - 1.5
6.2 - 9.6
0.02 - 0.2
0.005 - 0.5
0-15
7.0 - 20
10 ± 1
0.09 - 0.25
140 - 193
18 - 30
 *Compiled by  Lee,  1966.

 *Concentrations dependent  on  sampling  location  and  date.

the hypolimnion of Lake Mendota has become completely
anoxic each year since the early 1900Ts, it is felt
that the Cisco inhabited a narrow layer of water just
below the thermocline.  The oxygen in this layer is
maintained by diffusion through the thermocline.   By the
early 1940's, the rate of oxygen depletion in this region
of the lake was sufficient to cause anoxic conditions
immediately below the thermocline with the result that
the Cisco were deprived of their niche and died in large
numbers.  Of the 61 species of fishes reported for Lake
Mendota, 60 are listed among the 173 species in 29 families
found in the Great Lakes drainage.  The families Cyprinidae
and Centrarchidae  contribute the largest number of species,
The Percidae ana Ictaluridae are also well represented
(McNaught, 1963).
                            327

-------
      Changes  in  the  populations  of  aquatic  macrophytes
 have  also  occurred.   In  the  past 50 years Myriophyllum
 spicatum has  invaded the lake  and is presently the most
 abundant aquatic vascular plant  in  Lake Mendota.   In
 1921, the  most abundant  species, in descending order of
 abundance, were  Vallisneria  spiralis,  Najas flexidis,
 Potomogeton Richardsonii, P. zostenformis  and P.  pectin-
 atus  (Nichols and Mori,  1971).
   Table 5.  DISTRIBUTION OF COMMON SUMMER ZOOPLANKTERS
             IN LAKE MENDOTA (SUMMER, 1947)

Based on Clarke-Bumpus and Juday trap samples at 0-1 meter:
m, mean number of organisms per liter; s2, single haul
variance.*
Species
Clarke-Bumpus
Juday Trap

LAKE MENDOTA
Daphnia
longispina
Diaptomus sp.
Cyclops viridis
Copepod
nauplii
Chydorus sp.
Lecane sp.
(Rotatoria)
Asplanchna sp.
(Rotatoria)
m
36
10
6
20
26
24
9
S2(s2/m)
106(2.9)
29(2.9)
4(0.7)
15(0.8)
63(2.4)
75(3.0)
8(0.9)
m
26
11
7
39
31
35
11
S2(s2/m)
67(2.6)
38(3.4)
13(1.9)
180(4.6)
70(2.3)
126(3.6)
38(3.4)
*After Hasler, in Frey (1963).
NUTRIENT BUDGETS

     Estimated nutrient sources for Lake Mendota after the
1971 diversion of wastewater discharges are listed in
Table 6 (Sonzogni and Lee, 1974).  A breakdown by chemical
species of the nutrients input from each source is provided,
From these data a generalized nutrients budget for the lake
can be obtained (Table 7).  The phosphorus and nitrogen
loadings are 1.2 g P/m2/yr and 13 g N/m2/yr> respectively.
                              328

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-------
      Table  7.   NUTRIENT  SOURCES  FOR  LAKE  MENDOTA*
 A.  Phosphorus

 Domestic Wastewaters
 Urban Runoff
 Rural Runoff
 Precipitation
 Dry Fallout
 Ground Water
 Base Flow
 Kg/yr

    908
  7,264
 31,326
    908
  3,178
    454
  5,448
      TOTAL
 49,486
 B.  Nitrogen

 Wastewater
 Urban Runoff
 Rural Runoff
 Precipitation
 Dry Fallout
 Ground Water
 N-Fixation
 Base Flow
 Kg/yr

  3,133
 33,142
236,080
 31,326
 61,290
 77,634
 39,952
 61,290
      TOTAL

 ''After Sonzogni and Lee (1974).
543,847
     Despite the wastewater diversion, the mean phosphorus
content of Lake Mendota has increased during the period
between 1970-1973.  Data collected by Sonzogni (1974) pre-
sented in Table 8, show the mean phosphorus content of the
lake for this period.  The calculated mean phosphorus lake
concentration, based on these values and the total lake
volume (486 x 106m3), ranges from 0.12 to 0.15 mg/1.  A
mean value of 0.10 mgP/1 is obtained if one divides the
estimated phosphorus input by the volume of the lake.  This
is interesting in that it appears that one could predict
the mean annual total phosphorus concentration for Lake
Mendota based solely on input data.
                            330

-------
    Table 8.   MEAN MONTHLY, WINTER AND ANNUAL PHOSPHORUS
                CONTENTS FOR LAKE MENDOTA*

Mean
Content
Aug
Sept
Oct
Nov
Dec
Jan
Feb
March
April
May
June
July
Wintera
Annual
19
kg
70-19
x 10
DRP
5.
5.
5.
5.
4.
5.
5.
5.
1.
1.
3.
4.
5.
4.
7
5
8
3
9
2
0
3
7
9
6
8
1
6
71
-4
TP
7.
7.
7.
5.
5.
5.
5.
6.
4.
3.
4.
6.
5.
5.
0
2
2
9
8
9
8
1
6
0
8
3
8
8
1971-1972
kg x 10~4
DRP
5.
6.
5.
5.
5.
4.
4.
4.
4.
4.
4.
5.
4.
5.
3
3
6
5
2
2
3
7
9
6
2
1
6
0
TP
6
8
7
6
6
6
5
5
6
6
5
6
5
6
.9
.0
.3
.9
.4
.0
.4
.6
.4
.0
.8
.9
.9
.5
1972-1973
kg x 10~U
DRP
6.
6.
6.
6.
6.
6.
6.
7.
7.
6.
4.
3.
6.
6.
2
2
4
1
2
2
5
2
1
4
5
9
3
1
TP
8.1
7.6
7.7
6.9
6.9
7.1
7.1
8.4
8.1
7.2
6.6
6.2
7.0
7.3
 Average for Dec, Jan and Feb

 Average for Aug through July
*After Sonzogni (1974)
 DISCUSSION
      A summary  of  available  nutrient  loading data  is
 presented  in  Table 9.   The Vollenweider  (1974)  loading
 curve values  based on  the data  presented here,  are
 1.2  gP/m /yr  for phosphorus  loading and  2.7  m/yr for
 discharge  height,  q .   When  these  values are plotted  in
 the  loading vs. q   flot (Vollenweider, 1974),  Lake
 Mendota falls in The eutrophic  category  (Figure 2).   In
 addition,  this  plot shows Lake  Mendota to be in a
 higher eutrophic state than  was thought  in 1965.   It
 should be  noted that Vollenweider  (1974) uses  a q
 value significantly smaller  than the  2.7 m/yr  whiSh was
 an error in his original phosphorus loading  lake response
 curve relationships.

                             331

-------
  Table 9.   SUMMARY OF AVAILABLE NUTRIENT LOADING DATA
(1)  Nutrient Loadings

       Total Phosphorus
       Total Nitrogen

(2)  Chlorophyl-a
 49,500 Kg/yr 1.2 g/m /yr
543,800 Kg/yr 13  g/m2/yr
       Average total in lake        5,000 Kg
       Maximum total in lake        8,000 Kg
       Average for euphotic zone
       Maximum for euphotic zone
       Average primary production
       (estimated)

(3)  Physical Features of Lake Mendota
       Mean Depth
       Maximum Depth
       Area
       Total Volume
       Depth of Euphotic Zone
       Volume of Euphotic Zone
       Hydraulic filling time
       Discharge height, q
12 m
23 m   7
39.4 Km\
486 x 10 m
 3m   c Q
90 x 10 m
 4.5 yr
 2.7 m/yr
              125
              200
               25
               40 mg/m

                4g C/m2/day
     Examination of chemical characteristics through an
annual cycle, and algal assay studies such as those of
Walton and Lee (1972) as well as others at the University
of Wisconsin at Madison (G. P. Fitzgerald), have shown
the phosphorus concentration of the water is the key
factor governing the excessive growth of planktonic
and attached algae during the summer.  Stauffer and Lee
(1973) have demonstrated that many of the obnoxious
blue-green algal blooms that occur in summer are caused
by thermocline downward migration.  This results in the
transport of hypolimnetic phosphorus to the epilimriian.

     According to Vollenweider (1974), the current phos-
phorus loading of Lake Mendota is about ten times the
"permissible" loading.  Because the lake receives its
nutrients primarily from diffuse rural sources (Table 7),
reduction of phosphorus loading to the "permissible" level
does not appear to be likely.  In fact, it appears that
technical, economic and political factors involved
would make significant reduction of these loads difficult,
if not impossible (Lee, 1972).
                            332

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     In order for the public to perceive a significant
reduction in the frequency and severity of excessive blooms
of planktonic blue-green algae, the phosphorus loadings
would have to be decreased by at least a factor of five.
Yet according to Vollenweider (1974), despite a re-
duction of this magnitude, the lake would still have a
"dangerous" phosphorus loading level.

     From an overall point of view, as a result of increased urban-
ization of the Lake Mendota watershed, it is highly likely that water
quality in the lake will slowly deteriorate.  Increased
frequency of severe blue-green algal  blooms and excessive
growth of attached algae and macrophytes in littoral
areas  during the summer can be expected.  Based on the
current technology, it appears that  efforts to control
water  quality deterioration from  excessive fertilization
of the lake should be directed towards maximal reduction
of the phosphorus input from agricultural drainage and
urban  storm drainage.  With respect  to the former, par-
ticular emphasis should be given  to  controlling phos-
phorus input from animal manures  associated with  dairy
farming.  While  it appears very unlikely that efforts
to curb phosphorus input to Lake  Mendota will create a
measureable improvement in lake water quality, they
probably will benefit area residents  by slowing the de-
terioration.

     As Lee noted in 1972, the use of chemicals such as
alum to precipitate phosphorus could  improve Lake Mendota
water  quality.   This potential  solution is both technically
and economically feasible.  The evidence available today
clearly indicates that such a procedure would reduce
significantly the frequency of the severe blue-green
algal  blooms that occur each summer.  While alum  should
be used to  treat the open waters  of  the lake, simultaneously
a combination of mechanical weed  harvesters and aquatic
herbicides  should be used to control  excessive attached
algae  and macrophyte growth in  selected areas of  the lake.

     It is  technically and economically feasible  to
improve the water quality of Lake Mendota through judi-
cious  use  of chemicals to control both excessive  phos-
phorus and  excessive plant growth.   However, it is not
politically feasible at this time because environmental
activist groups  wield sufficient  political power  to pre-
vent use of such techniques although they have proven
highly successful elsewhere.
                            334

-------
                          ACKNOWLEDGMENTS
Information which serves as a basis for this report was collected through
the support of numerous granting agencies.  However, primary support for
many of these studies was derived from US EPA and  its predecessor organi-
zations.  In addition, substantial support to these studies was given by
the University of Wisconsin-Madison, especially the Departments of Botany,
Zoology, and Civil and Environmental Engineering.  Special recognition is
given to the assistance of J. Magnuson and A. D. Hasler of the University
of Wisconsin-Madison laboratory of limnology for their help in compiling
various reports used in this investigation.
                            REFERENCES
  1.   Bortleson,  G.  C. and G.  F.  Lee, Recent  Sedimentary
         History  of  Lake Mendota, Wisconsin.  Environ. Sci.
         Teohnol.  6_:  799-808,  1972.

  2.   Bryson,  R.  A.  and R. A.  Ragotzkie, Rate of Water
         Replacement  in a Bay  of  Lake Mendota,  Wisconsin.
         Amer.  J.  Sci. 253:  533-539, 1955.

  3.   Bryson,  R.  A.  and V. E.  Suomi, The Circulation of
         Lake  Mendota. Trans.  Amer.  Geophys.  Union. 33:
         707-712,  1952

  4.   Clarke,  D.  B.  and R. A.  Bryson, An Investigation of
         the Circulation over  Second Point  Bar,  Lake Men-
         dota.  Limnol. Oceanogr.  4_:  140-144,  1959.

  5.   Cline, D. R. Geology and Ground-Water Resources of
         Dane  County, Wisconsin.  USGS Water-Supply Paper
         1779-U,  1965.

  6.   Conway,  C.  J.  Oxygen Depletion in the Hypolimnion.
         M.S.  Thesis, University  of  Wisconsin,  1972.

  7.   Frey, D.  G.  (ed.) Limnology in North America.  The
         University  of Wisconsin  Press, Madison, 1963.

  8.   Lee, G.  F.  Studies on  the Fe,  Mn, SO^ and  Si Balances
         and Distribution for  Lake Mendota, Madison,
         Wisconsin.  Trans. Wisconsin Acad.  Sci.  Arts Lett.
         51: 141-155, 1962.
                                335

-------
 9.   Lee, G.  F.  Ways in Which a Resident of the Madison
        Lakes Watershed May Help to Improve Water Quality
        in the Lakes. A report of the Water Chemistry
        Program, University of Wisconsin, 1972.

10.   Lee, G.  F.  Water Chemistry Program Report No. A-18
        University of Wisconsin, 1966.

11.   McNaught, D. C. The Fishes of Lake Mendota. Wis. Acad.
        of Sci.  Arts and Lett. 52: 37-55, 1963.

12.   Murray,  R.  C. Recent Sediments of Three Wisconsin
        Lakes.  Bull. Geol. Soc. Amer., 67: 883-910, 1956.

13.   Nichols, S. A. and S. Mori, The Littoral Vegetation
        of Lake Wingra. Trans. Wise. Acad. Sci. Arts and
        Letters.  _59_:  107-119, 1971.

14.   Ryther,  J.  H. and C. S. Yentsch, The Estimation of
        Phytoplankton Production in the Ocean from
        Chlorophyll and Light Data.  Limnol. Oceanogr.
        2_:  281-294, 1957.

15.   Shulman, M. and R. A. Bryson, The Vertical Variation
        of Wind Driven Currents in Lake Mendota.  Limnol.
        Oceangr. 6_:  347-355, 1961

16.   Sonzogni, W. C.  "Effect of Nutrient Input Reduction
        on the Eutrophication of the Madison Lakes", Ph.D.
        Thesis,  Water Chemistry, University of Wisconsin,
        Madison, 1974.

17.   Sonzogni, W. C. and G. F. Lee  Nutrient Sources for
        Lake Mendota - 1972.  Trans. Wisconsin Acad. Sci.
        Arts and Letters. 62:  133-164, 1974.

18.   Stauffer, R. E. and G. F. Lee, The Role of the Ther-
        mocline in Regulating Algal Blooms.  In:  Modeling
        the Eutrophication Process, Workshop Proc., Utah
        State University, Nov. 1973.

19.   Torrey,  M.  S. Biological Nitrogen Fixation in Lake
        Mendota.  Ph.D. Thesis, University of Wisconsin,
        1972.

20.   Twenhofel, W. H. The Physical and Chemical Character-
        istics of the Sediments of Lake Mendota,  A Fresh-
        water Lake of Wisconsin.  Jour. Sed. Pet. _3_:   68-76,
        1933.

21.   Vollenweider, R. A.  Input-Output Models.  Canada
        Centre for Inland Waters, Mimeo,  1974.

22.   Walton, C. P. and G. F.  Lee, A Biological Evaluation
        of the Molybdenum Blue Method  for Orthophosphate
        Analysis.  Verh. Internat. Verein Limnol. 18:
        676-684, 1972.
                             336

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             REPORT ON NUTRIENT LOAD - EUTROPHICATION RESPONSE

                         OF LAKE WINGRA, WISCONSIN


                        Walter Rast and G. Fred Lee
                    Institute for Environmental Sciences
                        University of Texas at Dallas
                             Richardson, Texas
                                INTRODUCTION
     Lake Wingra is the smallest of the lakes of the Yahara River chain at
Madison, Wisconsin.  It is a shallow, hardwater eutrophic lake.  The drainage
area of Lake Wingra is composed of the University of Wisconsin Arboretum and
a portion of the urban region of southwest Madison.

                           GEOGRAPHIC DESCRIPTION
     Lake Wingra is located within the city of Madison, Wisconsin.  The lati-
tude and longitude of the centroid of the water area are 43°04.2' N and
89°23.6' W, respectively.  The lake surface stands at an altitude of 848 feet
above sea level (Huff et al., 1973).   The size and location of Lake Wingra
relative to the other lakes of the Yahara River chain are illustrated in
Figure 1.  The drainage basin is composed of a portion of the urban region
of southwest Madison, and the University of Wisconsin Arboretum, approximately
one-third of which drains directly to the lake.  The urban area enclosed by
the Lake Wingra drainage basin comprises residential middle- and upper middle-
class homes (Kluesener and Lee, 1974).  The lake has a cumulative drainage
area of 8.1 mi2 (2.1 x 107 m2) including lake surface area, but 2.2 mi2
(9 x 106 m2) drain directly into Murphy Creek, bypassing Lake Wingra proper.
Murphy Creek is the major outlet from Lake Wingra and flows directly into
Lake Monona.

                                   CLIMATE
     The climate of the basin is typically continental.  The summers are hot and
the winters cold.  The annual average temperature at Madison is 46.2°F and ranges
from an average of 17.7°F in January to an average of 72.7°F in July.  During

                                     337

-------
                     Figure I
Lakes of the Yahara River chain at Madison, Wisconsin*
                       338

-------
the winter months, December through March, the mean monthly
temperature is below 32 F.  The growing season generally
extends from late April to mid-October and averages 175 days
(Cline, 1965).
Although the record for Lake Wingra is incomplete, from 1877
to the present the lake froze over, on the average, on No-
vember 25 and thawed on March 29, for an average ice-bound
period of 125 days (Noland, 1950, cited in Frey, 1963).
The precipitation varies widely during the year.  The maximum
and minimum monthly precipitation occur in June and February,
respectively.  During May through September, there are
generally three to four inches of precipitation occurring
per month.  Between one and two inches of precipitation per
month  usually occurs during November through February.  The
total yearly precipitation at Madison averages 31.2 inches,
which includes an average annual snowfall of 37.8 inches, or
about seven inches of precipitation.  The evapo-transpiration
rate from that part of the Yahara River basin covered by
lakes and marshes is about equal to the precipitation (Cline,
1965).

GEOLOGIC DESCRIPTION

Lake Wingra occupies a pre-glacial valley system evacuated
by streams in sandstones and sandy dolomites of upper Cam-
brian Age.  The lake was formed as a result of morainic dam-
ming during the most recent ice age (Twenhofel, 1933).  Rocks
of Cambrian Age, principally sandstone and dolomite, were
deposited in shallow seas on a surface of igneous and meta-
morphic rocks of Precambrian Age ; dolomite and sandstone of
Ordovician Age were deposited on the Cambrian rocks.  Glacial
drift and loess overlie these formations (Cline, 1965).
                              339

-------
Most of Lake Wingra's immediate shores are swamp and bog,
and its shoreline material is mostly the lake's own organic
deposits (Murray, 1956).

CHARACTERISTICS OF WATERSHED

Most of the vegetation surrounding Lake Wingra is that of
the University of Wisconsin Arboretum.  It is composed
principally of coniferous and decidous forests, prairies,
gardens and marshes.  The Arboretum comprises approximately
800 acres, 20 percent of the drainage area of the lake.  Of
this 800 acres, approximately 470 acres consist  of forests,
while the remaining 330 acres consist of prairies, gardens
and marshes (Kluesener, 1972).
Approximately 200,000 people reside in Madison, Wisconsin,
on the northeast shore of Lake Wingra.  Land usage in the
Lake Wingra drainage basin is summarized in Table 1.

      Table. 1.  LAND USAGE IN LAKE WINGRA DRAINAGE BASIN*



Lake Wingra Basin
Area draining to Lake Wingra
Residential Area
Arboretum
Lake and Ponds
Area draining directly to Murphy Creek

Acres
5200
3800
2600
775
337
1400
Area
Hectares
2104
1538
1052
314
136
566
*After Kluesener, 1972
                              340

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The residential drainage area consists mainly of storm sewer
drain outlets, and also includes approximately 100 acres of
golf courses and cemeteries (Kluesener, 1972).
Lake Wingra is used mainly for sports, fishing and recrea-
tion.  There have never been any sewage or industrial dis-
charges into Lake Wingra (Sonzogni, 1974) except for oc-
casional sewer overflow due to failure of the sewage pump-
ing station.

            MORPHOMETRIC AND HYDROLOGIC DESCRIPTION

Lake Wingra has a surface area, including lagoons and ponds,
                          c  o
of 137 hectares (1.37 X 10  m ).  It has a maximum length of
2.09 km, a maximum effective length of 2.16 km, a maximum
width of 1.11 km and a mean width of 0.63 km.  The shoreline
is 5.91 km long.  It has a shoreline development figure of
1.45 and a development of volume of 1.19.  The water volume,
                                                         p
including ponds and estimated lagoon volume, is 3.35 X 10 -
 3
m .  The maximum depth of the lake is 6.10 m and the mean
depth (volume/surface area) is 2.42 m (Figure 2) (Huff et
al. , 1973).  Because of its shallow mean depth (2.42 m) ,
the lake does not permanently thermally stratify; the epi-
limnion generally extends to the bottom all year round
(Murray, 1956).

CHARACTERISTICS OF SEDIMENTS

The sediments of Lake Wingra have been studied extensively.
The shore and bottom deposits are predominantly marl.  In
the sixties, Frey (1963) established that the recent bottom
consists of gray marl, which becomes shell marl in shallow
water.  Murray (1956) established that the top six inches
of recent sediment are a gray to dark gray marl.  At least
                               341

-------
342

-------
some locations in the lake contain abundant gastropod shells
and clam shell fragments.  The carbonate content is approxi-
mately 54 percent in the most recent sediments.  The organic
matter present in the sediment ranges from 11.7 to 13.5 per-
cent (similar in organic content to the black sludge and
buff marl of Lake Mendota).  The elastics appear to be con-
centrated in the fine sizes.  The surrounding bogs of Lake
Wingra permit very little clastic deposition because little
clastic material is available on the shore.  The lack of
black sediments similar to those found in Lake Mendota is
thought to be evidence that Lake Wingra has a constant avail-
ability of oxygen throughout the epilimnion, which extends
to the bottom.  A sediment core analysis was conducted by
Bortleson (1970), and the results of the upper five cen-
timeters  are summarized in Table 2.

        Table 2.  SEDIMENT ANALYSIS FOR THE UPPER
                    5 CM OF DRY SEDIMENTS*

Component
Fe
N
P
Ca
Lake Mendota
(mg/g dry wt)
20-25
10
2
125
Lake Wingra
(mg/g dry wt)
9
7-8
0.6
230-240
*After Bortleson, 1970
More recently, Bannerman (1973) examined Lake Wingra sedi-
ments in some detail for interstitial concentrations of in-
organic phosphorus.  He found that levels of total phosphorus,
total inorganic phosphorus and total organic phosphorus
                             343

-------
present in core samples from both the open water areas and
littoral zone were in good agreement with values for Lake
Wingra sediments reported previously by others (Williams
et al_. , 1971; Li et_ a^. , 1972).  By contrast, sediments
from lakes Mendota and Monona revealed levels of phosphorus
approximately twice as large as those in Lake Wingra
(Williams et_ al., 1970).  It is believed this is due to the
nature of the input waters into these lakes.   Lake Wingra
receives primarily urban runoff (Lee and Kluesner, 1971),
while Lake Mendota and Lake Monona receive a combination of
urban and agricultural runoff.

HYDROLOGY

The hydraulic residence time (water body volume/annual in-
flow volume) was calculated to be 0.4-4 years, based on
data from Kluesner (1972) and Huff et_ al. (1973).  The
annual input for Lake Wingra is the sum of the precipitation,
springflow, urban runoff and groundwater input.  The USGS
data as reported by Kluesner (1972) was used for the annual
precipitation, springflow and urban runoff inputs (1 X 10°
m3/yr,  1.4 X 106 m3/yr and 1.0 X 106 m3/yr, respectively).
Kluesner did not report the groundwater input to the lake.
As the groundwater input is considered to be essentially
constant, Huff's groundwater input for the period April 10
to September 15, 1970 (158 days) was extrapolated to a full
year (=2.3 X 10^ m3/yr) and used in the calculation of the
hydraulic residence time.  Thus, the hydraulic residence
time is calculated to be 0.44 years (i.e., lake volume
(2.5 X 106 m3)/total annual input (5.7 X 106 m3/yr)).
A water balance summary for Lake Wingra for the period
April 10, 1970 to September 15, 1970 is presented in Table 3.
                              344

-------



















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               PHYSICAL AND CHEMICAL DESCRIPTION

Dissolved oxygen studies (Kluesener, 1972) have shown that
the lake is poorly mixed in the vertical plane when covered
with ice.  This is contrasted with relatively infrequent
vertical stratification, with respect to dissolved oxygen,
during the summer.
Lake Wingra was sampled for temperature, pH, dissolved
oxygen (DO), alkalinity, calcium and total phosphorus and
nitrogen, including N and P species, at four open water and
four littoral zone stations.  Sampling frequency was limited
to collecting samples every two weeks.  The sampling period
ranged from twelve to eighteen months, depending on the
parameter studied.  Samples were collected at the one and
two meter depths, with occasional sampling at three meters
if the lake was sufficiently high.  Kluesener (1972) pro-
vides the details on the characteristics of the sampling
program, analytical methods and data obtained in the study.
A summary of Kluesener's (1972) results are presented below.
Throughout most of the year the temperature was constant
over the extent of the water column (Figure 3).  Differences
were seen at 1 m and 3 m depths during the winter as the
bottom waters gained some heat from the lake sediments.
After ice-out the lake warmed rapidly and was about 13 C by
the end  of April of both 1970 and 1971.  The normal summer
temperatures averaged approximately 23°C until the cooling
trend began in September (Kluesener, 1972).  In the winter
when the water is clear, the Secchi disk reading was approxi-
mately 2 m  (Figure  3).  It was reduced to about 1 m after
ice-out  in both 1970 and 1971.  From May to September in
both 1970 and 1971, it was further reduced to 0.6-0.7 m.
                              346

-------
Hd
        3-
O
CJ
O
O
IHDD3S
                                      wnionvo
                          347

-------
Light intensity was measured throughout the ice-free period
in the air above the water, just below the water surface and
at the depths of 0.5, 1.0 and 2.0m.  Between April and
August, 1970, average values were 32 percent, 13 percent
and 3.2 percent transmitted through the first 0.5 m, the
upper 1 m and the upper 2 m, respectively (Table U).  The
corresponding Secchi disk reading was about 0.85 m.
The pH (Figure  3) averaged 7.7 throughout the winter of
1970.  It increased after ice-out to a maximum of 9.4 dur-
ing September and October, and then decreased to 7.7 again
by March, 1971.
The annual variations in the dissolved oxygen content for
1 and 3 m are also given in Figure 3.  The dissolved oxygen
(DO) content was approximately zero by late winter of both
1970 and 1971 and remained at that level until ice-out.  In
the upper meter of the lake water column, the DO decreased
at a relatively constant rate in January and February of
both 1970 and 1971.  The average oxygen depletion rate was
approximately 0.18 mg DO/l/day.  In March, 1971, the oxygen
depletion rate was much slower, and it took nearly the
entire month to remove the remaining 1.5 mg/1 DO at the 1 m
depth.  The DO then rose sharply as soon as ice-out occurred,
and the water column remained essentially saturated at all
depths throughout the open water period.  The only excep-
tions were moderate DO stratifications during sampling in
June and July, 1970.  In the mornings, the DO in the litto-
ral sampling stations showed a slightly higher concentration
than in the main body of the lake.  Also, the DO showed a
definite increasing tendency in progressing from the first
lake station to the final station.  It is believed this
higher DO concentration in the littoral zones was  due  to
the presence of macrophytes, especially Myriophyllum, in
                              348

-------
      Table 4.   PERCENT OF LIGHT MEASURED JUST ABOVE THE
       SURFACE OF LAKE WINGRA WHICH ACTUALLY PENETRATES
             TO A SPECIFIED DEPTH (0.5, 1.0, 2.0m)
                         IN THE LAKE*

Date
Apr 11 1970
Apr 27
May 11
May 25
June 5
June 22
July 6
Aug 3
Aug 17
Aug 31
Sep 14
Sep 28
Oct 12
Oct 26
Nov 23
Apr 13 1971
Apr 26
0.5m
33
33
26
26
63
28
26
35
18
34
44
44
37
55
65
48
38
Depth
1.0m
16
21
7.3
11
32
10
10
12
7
9
19
16
12
22
30
24
18
2.0m
4
7
2

12
3
2
2

1
6
4

7
10


Secchi Depth
m
1.0
1.0
0.75
0.90
1.5
0.85
0.75
0.65
0.60
0.60
0.65
0.70
0.80
1.05

0.65
0.95
•'After Kluesener,  1972
                             349

-------
the littoral zone throughout the winter, as these organisms
are able to undergo photosynthesis even under ice and at
light intensities below those required for algae (Kluesener,
1972).  A relatively sharp oxygen stratification between the
1 and 3 m depth in the winter indicates this lake is very
poorly mixed in the vertical plane when covered with ice.
The data for the average phosphorus concentrations are sum-
marized in Figure H.  After mid-January, the total phosphorus
(t-P) concentration of the lake remained nearly constant at
approximately 0.06 mg P/l.  The annual average t-P concentra-
tion was 0.07 mg P/l; the annual average dissolved reactive
phosphorus (DRP) concentration was 0.02 mg P/l.  The average
DRP concentration was approximately 0.08 mg P/l throughout
the growing season, and nearly O.OU mg P/l at the end of the
winter season.
The average annual variation for the nitrogen species in
Lake Wingra is summarized in Figure 5.  The total nitrogen
concentration varied from 1.0 to 1.8 mg N/l for the study.
The inorganic nitrogen (i.e., NO--N and NH^-N) concentration
averaged 1.51 mg N/l for the entire year and 1.01 mg N/l
for the growing season (i.e., May through September).
Comparison of both the phosphorus and nitrogen data with
earlier studies (Domogalla and Fred, 1926; Tressler and
Domogalla, 1931; and Clesceri, 1961) suggests that there
has been little change in the average levels of nitrogen
and phosphorus in Lake Wingra in the last M-5 years  (Kluese-
ner, 1972).
The inorganic nitrogen/dissolved reactive phosphorus and
 atomic  ratios during  the  annual  cycle and during the
 growing season, are greater  than 30.  As a critical N:P
 atomic  ratio  of 16  or  greater in natural waters  is  indicative
 of phosphorus limitation, this  suggests that Lake Wingra
 is phosphorus limited  with respect to aquatic plant nutrients .
                               350

-------
fc
970 to June
Figure 4
Average concentration of phosphorus in the open water of Lake Wingra from January 1
CM
N
0)
luesener,
*After K
imit for phosphorus LEGEND1
V

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Ived reactive L
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Alkalinity was at a maximum during the winter months (see
Figure 3), decreasing after ice-out as the temperature and
biological activity increased.  It .decreased, in a nearly
linear fashion from the end of April to the end of Septem-
ber.  It remained constant in October, and then increased
to approximately 200 mg/1 as CaC03 in March, 1971.  The
calcium concentration showed more variability during this
same time period, but it followed the same general trend
as the alkalinity (Kluesener, 1972).

                    BIOLOGICAL DESCRIPTION

ALGAE

The mean annual freshweight phytoplankton biomass in Lake
                               2
Wingra was approximately 16 g/m  in 1970-71, with a growing
                                      2
season average of approximately 25 g/m  (Figure 6).  The phyto-
plankton primary productivity was found to be about 2.4- g C/
 2               2
m /day (870 g C/m /yr), with a growing season average of about
        2
4.6 gC/m /day.  The phytoplankton class composition pattern
for the same time period (Figure 7) shows the winter phyto-
plankton biomass to be dominated by the algae Cryptophyceae,
while the spring season shows a dominance by the diatoms.
They rapidly give way to the green algae.  This is followed
in the late summer and early fall by a dominance of the blue-
green algae.

FISH

Early management practices (e.g., introduction of carp in
the late 1880's, fish rescue and stocking operations during
the 1930's, and carp removal programs during the 1930's,
1940's and 1950's) have had marked effects upon the fish
populations in Lake Wingra.  A total of 23 fish species have

                              353

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                            Figure  6
    Average  daily productivity and freshweight biomass  of
    phytoplankton in Lake  Wingra.*
                                      •	• PRODUCTIVITY
                                      o—o FRESHWEIGHT
80 m
   en
   x

601
                                                             401
                                                               A
                                                               •^
                                                               3
                            Figure 7
   Class composition pattern for phytoplankton in Lake Wingra*
100
                                  H h
                                      ICE COVER
                                                 QCRYPTOPHYCEAE
                                                 QTJ CHLOROPHYCEAE
                                                  2) CHRY30PHYCCAE
                                                 =3 BACILLARIOPHYCEAF
                                                   MYXOPHYCEAE
                                                   DINOFHYCF-AE
                                                   EUGLENOPtlYCEAE
   After Huff et al., 1973
                             354

-------
been introduced into Lake Wingra at one time or another in
the past.  Of these, two—the yellow bass and white crappie-
have become abundant.  The carp was introduced into Lake
Wingra in the 1880's and became extremely abundant by the
1950's.  Consequently, an intensive carp seining program
was instituted by the Wisconsin Conservation Department
between 1953 and 1955 because earlier efforts had not re-
duced the population to low enough levels (Neess et al,,
1957, cited in Hasler, 1963).  Both largemouth bass and
blueg.il!  populations have recovered since the carp popu-
lation became somewhat controlled (see Figure 8).  The blue-
gill responded by becoming the dominant species in the lake.
This increase, together with the establishment of white
crappie and yellow bass, have produced the large, stunted
panfish population which characterizes the present sport
fishery (Baumann et al., 1974).

ZOOPLANKTON

Of the 48 cladoceran species present in Lake Wingra in
1891, only 23 are still present today (Table 5) (Baumann
ejt al. , 1974).  Only four new species have been added to
the list during this period.  Sampling of the benthos dur-
ing 1970-1972 has shown an invertebrate fauna dominated by
small chironomids.  No live mollusks or relatively large
insects were found.   The macroinvertebrate Hyalella azteca
has virtually vanished.  Intense fish predation on larger
invertebrates may explain the rather recent decline of
larger cladocerans and benthos in Lake Wingra.
                             355

-------
(xlO)
(xlO)
                   Figure 8

Relative abundance of major fishes in Lake Wingra

from 1890 to 1973, reconstructed from the literature*

                                  LONGNOSE GAR

 //////////////////////TTTv
                                     IORTHERN PIKE
                                  LARGEMOUTH BASS
(xlO)l
                                      WALLEYE
                                     YELLOW PERCH
     CARP
       i     i     i     r     i     i     r     i     T

     1890   1900   1910  1920  1930   1940  1950  I960  1970
          V)
          Q
                 0:6x0
                 OCEQ.Z
                 -
                       ^
                       02
         H

3o

23
CD <
   After Baumann etal.1974
                        356

-------
Table 5.  CLADOCERAN SPECIES RECORDED FROM LAKE WINGRA
          BY BIRGE (1891) AND MORE RECENT STUDIES BY
          WHITE AND HASLER (1972)*

SPECIES
Acroperus harpae
Alona affinis
Alona costata
Alona guttata
Alona quadrangularis
Alona rectangula
Alonella excisa
Alonella exigua
Bosimina longirostris
Camptocercus macrurus
Camptocercus rectirostris
Ceriodaphnia laticaudata
Ceriodaphnia megalops
Ceriodaphnia pulchella
Ceriodaphnia quadrangula
Ceriodaphnia reticulata
Chydorus globosus
Chydorus ovalis
Chydorus sphaericus
Daphnia ambigua
Daphnia galeata
Daphnia pulex
Daphnia retrocurva
Daphnia schodleri
Diaphanosoma brachyurum
D. leuchtenbergianum
Drepanothrix dentata
Dunhevia crassa
Eurycercus lamellatus
Graptoleberis testudinaria
Holopedium gibberum
Ilyocruptus sordidus
Ilyocryptus spinifer
1891
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
PRESENT
1971
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
                       (continued)
                           357

-------
                    Table 5 (continued)
    SPECIES
PRESENT
                                         1891
* After Baumann et al. , 19 7 M-
       1971
Latona setifera
Latonopis occidentalis
Lathonuria rectrirostris
Leptodora kindtii
Leydigia quadrangular is
Macrothrix laticornis
Macrothrix rosea
Ophryoxus gracilis
Oxyurella tenuicaudis
Pleuroxus denticulatus
Pleuroxus procurvus
Pleuroxus striatus
Pleuroxus trigonellus
Polyphemus pediculus
Sida crystallina
Scapholeberis aurita
Scapholeberis kingi
Simocephalus serrulatus
Simocephalus vetulus

X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
TOTAL 48
X
X
X
X
X
X
X
X
27
                              358

-------
MACROPHYTES

Around 1900, the shallow areas of Lake Wingra were dominated
by cattails and bulrushes.  Wild rice abounded in slightly
deeper water, while submerged vegetation included water
celery and pondweed.  Dredging and filling in areas of the
original lake (in 1900 Lake Wingra had a shallower maximum
depth and covered about twice its present area) have pro-
duced water level fluctuations which have reduced the area
available for littoral growth.  In addition to hydrographic
changes, from the 1920's to the mid-1950Ts  the carp popula-
tion essentially denuded Lake Wingra of macrophytes.  After
the carp removal program of the 1950's, vegetation of a
different type returned to the lake.  The Eurasian water
milfoil, Myriophyllum spicatum, now dominates the macroflora
of Lake Wingra.
Presently, five littoral communities occur in Lake Wingra.
In shallow water, Myriophyllum constitutes 68 percent of the
macroflora.  In deeper waters, the communities are Myriophyl-
lum, 13 percent; Potamogeton-Myriophyllum, 17 percent;
Nuphar, 5 percent; and Nymphaea, 2 percent.  Dominant emer-
gents are Typha latifolia, T_. angustifolia and Scirpus
validus.  The littoral zone covers approximately one-third
of the lake's surface area and extends to 2.7 - 0.4 meters.
It is believed the littoral zone depth is dictated by light
penetration, and that major reduction in turbidity would
allow water milfoil stands to develop throughout the lake
(Baumann ejt al. , 1974).   Foraging by the carp population and
resultant mixing of the muds are believed to have caused an
increased turbidity and reduced light penetration.  Their
removal to less than 10 percent of their 1953 numbers by
seining has been followed by an increased macrophyte popula-
tion, indicating that control of the spread of macrophytes
                              359

-------
may have been one of their functions (Neess e_t al. , 1955,
cited in Kluesener, 1972).

                       NUTRIENT BUDGETS

Major potential nutrient sources for Lake Wingra have
been shown to be precipitation, dry fallout, springflow,
groundwater flow, urban runoff, surface runoff from the
Arboretum and drainage from the marshes.  The annual average
nutrient loadings from precipitation, dry fallout, spring-
flow and urban runoff are presented in Tables 6, 7, 8 and 9,
respectively.
Groundwater loading into Lake Wingra could not be estimated
by Kluesener because there was insufficient information
available concerning the piezometric head and transmissi-
bility of the soil in the lake vicinity.  It is likely that
any groundwater flow other than surface springs enters the
lake through submerged springs, but these sources have not
been identified.  The marshes are believed to have input
nutrient loads roughly equal to output nutrients.
The nutrient budget for Lake Wingra is summarized in Table
10.  The most significant source of phosphorus to Lake
Wingra is the urban runoff.  More than 80 percent of the
total phosphorus (980 kg/yr) and 90 percent of the dissolved
reactive phosphorus (570 kg/yr) influent to Lake Wingra
comes from this source (Kluesener, 1972).  Very little dis-
solved reactive phosphorus enters the lake between storms
(Huff e_t al. , 1973).  Precipitation, dry fallout and spring-
flow contribute almost equally to the dissolved reactive
phosphorus input (25, 21 and 30 kg/yr, respectively).  Pre-
cipitation on the lake surface contributes less than 2 per-
cent to the total phosphorus input.  The groundwater phos-
phorus contributions to the lake are not known at present,
                             360

-------
       Table 6.  AVERAGE ANNUAL LOADING OF NITROGEN
                 AND PHOSPHORUS TO LAKE WINGRA FROM
                 PRECIPITATION*
Loadings:

Ibs/ac/in

kg/yr/lake
0.089

390
                         NO~-N
 0.10

 440
Org-N


0.059

 260
                           DRP
                         t-P
                                          0.0057  0.0073
                                            25
32
                                                     6  3
Volume of water to the lake/30.16 in of rain = 1 X 10 m


*After Kluesener, 1972

         Table 7.  NUTRIENT LOADING OF LAKE WINGRA DUE
                   TO DRY FALLOUT*

Period
N
Hj-N
kg/da
Sep 26-Oct 4
Oct 15-Oct 24
Dec 10-Jan 1
Jan 1-Jan 31
Mar 6 -Mar 14
Mar 2 8 -Apr 4
Apr 2 6 -May 4
May 12 -May 18
Jun 6-Jun 14
0
1
0
2
1
1
2
2
1
.76
.85
.62
.08
.31
.06
.30
.50
.50
NO~-N
kg/da
0
1
1
2
1
0
1
0
0
.32
.25
.35
.08
.44
.36
.47
.59
.76
Org-N
kg/da
1.
1.
1.
0.
—
5.
2.
9.
1.
40
41
22
93
-
4
02
5
8
DRP
kg/da
0.
0.
0.
0.
0.
0.
0.
0.
0.
027
050
045
042
018
09
10
12
03
t-P Exposure
Time
Days
kg/da
0.
0.
0.
0.
0.
0.
0.
0.
0.
10
18
060
23
060
59
16
93
35
7.8
9.9
29 .0
22.0
8 .3
8.5
7.5
5.6
8.5
Average load
1.60
Average Annual Lake
Load (kg/yr)    565
1.30
         475
                                  3.0
         1100
         0.06  0.30
                                           21
               110
*After Kluesener, 1972
                              361

-------
        Table  8.   AVERAGE ANNUAL LOADINGS FOR SPRINGS
                  FLOWING INTO LAKE WINGRA*

Sparing
Flow NH
(cfs;
Wingra
Nakoma
Council Ring
East Spring
Duck Creek
April-Dec 20
Dec 20 -Apr 1
Total Spring
Input
Total Lake Input
0.
0.
0.
0.

0.
-

1.
= 1.
64
30
06
10

45
—

55
37
-N
l kg/yr
14.
44.
0.
3.

39.
70.

170.
X 106 m3
3
0
4
1

0
0

8
/yr
NO~-N DRP
O
kg/yr kg/yr
1690 8.5
700 5.5
46.5 0.3
12.2 1.6

1100 8.4
480 6.2

4138.5 30.5

t-P
kg/yr
14
19
0
2

18
22

77

.0
.7
.4
.7

.6
.0

.4

-After Kluesener,  1972
                              362

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        Table 10.   SUMMARY OF MEASURED NUTRIENT
                   SOURCES FOR LAKE WINGRA*

Source
Precipitation
Dry Fallout
Springf low
Urban Runoff
Total =
Lake Volume =
NH*-N
390
560
170
450
1570
2.5 X 106
NO~-N Org-N
3 (kg/yr)
440 260
480 1100
4140
60_0 350_0
5660 4860
3
m
DRP
25
21
30
570
646

t-P Vol. of3
waterCm )
32 IX '106
110
77 1.4 X 106
980 1 X 10 6
1199

* After Kluesener, 1972

but it is not believed that this is a significant source
(Kluesener, 1972).
The springflow contributes approximately 60 percent of the
inorganic nitrogen (i.e., NH^-N and NO~-N) influent to the
lake.  All other sources contribute approximately equal
amounts of inorganic nitrogen.  The urban runoff and spring-
flow each contribute about 35 percent of the total nitrogen.
Precipitation and dry fallout contribute about 10 percent
and 20 percent respectively, to the total nitrogen loading.
Thus, about 65 percent of the nitrogen budget of Lake Wingra
comes from  'natural'  sources.  The resultant lake nitrogen
concentration is thus more independent of storms than are
the phosphorus concentrations, since springflow and ground-
water provide significant nitrogen inputs to the lake between
storms (Kluesener, 1972).
                              364

-------
The volume of water contributed by rainfall, urban runoff
and springflow is approximately 3. "4 X 10  m /yr.  The aver-
age nitrogen and phosphorus concentrations of this input
                                          *.
are approximately 3.0 mg N/l and 0.3 mg P/l, respectively.
This is about four times the average concentration of phos-
phorus and three times the average concentration of nitrogen
(see Figures M- and 5) normally found in Lake Wingra (0.07 mg
total P/l and 1.1 mg total N/l, respectively).  If it is as-
sumed that Lake Wingra reacts like a large completely mixed
body of water, as the data indicate , then nitrogen and phos-
phorus are being accumulated in the lake sediments or are
being released to the atmosphere (Kluesner,  1972).

                       DISCUSSION

A summary of the available nutrient loading data and im-
portant physical features of Lake Wingra is presented in
Table 11.
Huff e_t a].. (1973) attempted to simulate urban runoff,
nutrient loading and biotic response in Lake Wingra based
on a Hydrologic Transport Model (HTM).   The nutrients con-
sidered in their open lake model were dissolved inorganic
phosphorus and dissolved inorganic nitrogen.  They con-
sidered  urban runoff, springflow, groundwater seepage,
rainfall, dry fallout and internal sediment nutrient re-
generation as nutrient sources.
Huff et a].. (1973) assumed the available phosphorus form
was dissolved inorganic phosphorus, and that this was a con-
stant percentage of the total phosphorus entering the lake.
However, Cowen (1973), studying the Madison area urban
drainage, has shown that approximately 30 percent of the
phosphorus in the particulate organic and inorganic forms
will become available for algal growth in natural water sys-
tems.  Therefore, the Huff e_t al.  (1973) estimates of the
                              365

-------
     Table 11.   SUMMARY OF AVAILABLE NUTRIENT LOADING DATA
                AND PHYSICAL CHARACTERISTICS*
I.   Nutrient Loadings

Total Phosphorus (t-P)              1199 kg/yr    0.88 g/m /yr
Dissolved Reactive Phosphorus (DRP)  646 kg/yr

Total Nitrogen (NH*-N, NO~-N &     12090 kg/yr    8.83 g/m2/yr
                      +    Org-N)
Inorganic Nitrogen (NH^-N S NO~-N)  7230 kg/yr

II.  Biomass S Productivity
                                                    2
Phytoplankton Biomass, Annual Average         16 g/m
Phytoplankton Biomass, Growing Season               2
  Average                                     25 g/m
Phytoplankton Primary Productivity
  Annual Average (870 g C/m2/yr)              2.4 g C/m2/day
Phytoplankton Primary Productivity,
  Growing Season Average                      4.6 g C/m2/day

III.  Physical Characteristics of Lake Wingra

Maximum Depth                                 6.10 m
Mean Depth                                    2.42 m   6 2
Surface Area, excluding lagoons  S ponds       1.37 X 10gnu
Total Volume, excluding lagoons  S ponds       2.50 X lOg^U
Annual Input                                  5.70 X 10 m
Hydraulic Residence Time                      0.44 yr
Mean Depth/Hydraulic Residence Time           5.5 m/yr
Mean Secchi Depth                             1.3 m

IV.  Chemical Characteristics of Lake Wingra

Mean Alkalinity                               153 mg/1 as CaCo-
Mean Calcium Concentration                      34 mg/1
Mean Conductivity                             Not Determined
Mean Annual DO                                1 m - 7.7 mg/1
                                              3 m - 6.6 mg/1
pH                                            Min.-7.7
                                              Max.-9.4
•'After Huff et al., 1973 and Kluesener, 1972
                             366

-------
available phosphorus input to Lake Wingra are expected to
be low due to the fact that Kluesener (1972) found that a
substantial part of the phosphorus entering the lake is not
in the immediately available form.  Further, it would be
expected that the marshes through which much of the urban
drainage enters the lake would significantly alter the
transport rate of available phosphorus to the lake, making
it essentially impossible, with the information available
today, to develop meaningful models which relate nutrient
transport in the urban areas of the Lake Wingra watershed
to algae and macrophyte growth in the lake.
The Vollenweider loading curve (Vollenweider, 1975; Vollen-
weider and Dillon, 197M-) values, based on data in Table 1L,
            2
are 0.88 g/m /yr for phosphorus loading and  5.5 m/yr for the
mean depth/hydraulic residence time.  When these values are
plotted according to Vollenweider (1975), Lake Wingra falls
in a category typical of lakes, with similar phosphorus
loadings and morphometric and hydrological characteristics,
which are considered eutrophic (Figure  9 ).  The current
phosphorus loading is about four times its "permissible"
loading rate for its mean depth and hydraulic residence time
characteristics.
The trophic status is in agreement with the physical, chemical
and biological characteristics of the lake.  Lake Wingra is
a shallow lake  with shallow sloping shoreline, in which the
thermocline is absent.  The hypolimnion volume is low or
absent, and it has low transparency.  The entire water column
can be affected by wind-generated mixing.  This situation
tends to promote increased nutrient cycling and therefore
a higher degree of eutrophication than for deeper lakes with
similar nutrient loads.  Blue-green algae are usually the
dominant forms during the summer months.  The fish present in
Lake Wingra are abundant in number, but mostly trash species
                             367

-------
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-------
such as carp (Neess et al., 1957, cited in Hasler, 1963;
Huff et al., 1973).

         IMPROVEMENT OF WATER QUALITY IN LAKE WINGRA

The overall water quality of Lake Wingra could be improved
somewhat with the cooperation of the residents of the portion
of the southwest corner of Madison, Wisconsin, which lies
within the Lake Wingra drainage basin.  The primary water
quality problem in Lake Wingra and the other Madison lakes
is an excessive amount of alga and waterweeds (particularly
Myrillophyllum in Lake Wingra) caused by excessive inputs of
aquatic plant nutrients such as nitrogen and phosphorus com-
pounds.  Studies by Walton and Lee (1972) and Fitzgerald and
Lee (1971) have shown the key factor governing the excessive
algal and waterweed growth in Lake Wingra is the concentra-
tion of phosphorus in the water.
As stated earlier, approximately one-third of the total
drainage to Lake Wingra comes from the University of Wisconsin
Arboretum, while the remaining two-thirds is urban runoff
from southwest Madison.  More significantly, the urban runoff
delivers approximately 80 percent of the total phosphorus
and 90 percent of the soluble orthophosphate (see Table 10)
to Lake Wingra.  Consequently, the amounts of nutrients
entering Lake Wingra by way of urban runoff could be sub-
stantially reduced by reduction of the phosphorus content of
the urban runoff.  To achieve this will require that each
individual living in the Lake Wingra drainage basin conduct
his activities in such a manner as to reduce, and wherever
possible, eliminate the transport of phosphorus to Lake
Wingra.  Particular attention should be given to improving
the efficiency and frequency of street cleaning in the urban
parts of the Lake Wingra watershed.  Lee (1972) has dis-
cussed in detail various methods that can be used by the
                              369

-------
 residents  of Madison to  improve  the water quality of  Lake
 Wingra  and the other Madison lakes.  Elimination of the
 phosphorus input  from urban runoff would lower  the annual
                               2
 phosphorus loading to 0.23 g/m /yr.  This reduced loading
 would place Lake  Wingra  in the oligotrophic trophic cate-
 gory, according to the Vollenweider criteria.   Realistically,
 of  course, this will not be achieved.  However, with  even
 a moderate reduction of  phosphorus input, Lake  Wingra could
 likely  become a less productive  body of water and achieve
 a significant reduction  in the frequency and severity of
 excessive  algal blooms and macrophyte  growth.

                       ACKNOWLEDGEMENTS

 Support for research which served as a basis for this  report
 was derived from  a variety of  federal agencies, especially
 the US  EPA and the US IBP program.  In addition, support
 was given  this investigation by The University of Wisconsin-
 Madison, especially the Departments of Botany,Civil and
 Environmental Engineering and  Zoology.  Special recognition
 is  given J. Magnusan  of the University's Laboratory of  Lim-
 nology  for his assistance in providing information on  Lake
 Wingra  fisheries.

                          REFERENCES
Bannerman, R.T.   Interstitial Inorganic Phosphorus in Lake
     Wingra Sediments.   MS Thesis,  University of Wisconsin,
     Madison,  1973.   120 p.
Baumann, P.C., J.F.  Kitchell, J.J.  Magnuson, and T.B. Kayes.
     Lake Wingra,  1837-1973:   A Case History of Human Impact.
     Trans. Wise.  Acad.  Sci.  Arts Lett.  6_2:57-94,  1974.
Birge, E.A.  List  of Crustacea Cladocera from Madison,
     Wisconsin.   Trans.  Wise. Acad. Sci. Arts Lett.   _8: 379-398,
     1891.
Bortleson, G.   The Chemical Investigation of Recent Sediments
     from Wisconsin.  Ph.D.  Thesis, University of Wisconsin-
     Madison,  1970.   278 p.
                                370

-------
Clesceri, N.L.   The Madison Lakes Before and After Diversion.
     MS Thesis, University of Wisconsin-Madison, 1961.   30 p.

Cline, D.R.  Geology and  Groundwater Resources of Dane  County,
     Wisconsin, USGS Water-Supply Paper 1779-U.  1965.   64 p.

Cowen, W.F.  Available Phosphorus in Urban Runoff and Lake
     Ontario Tributary Waters.  Ph.D. Thesis, University of
     Wisconsin-Madison, 1973.

Domogalla, B.P. and E.B. Fred.  Ammonia and Nitrate Studies of
     Lakes Near Madison, Wisconsin.  J. Am. Soc. Agron.  18;
     897-911,  1926.

Fitzgerald, G.P. and G.F. Lee.  Use of Tests for Limiting or
     Surplus Nutrients to Evaluate Sources of Nitrogen and
     Phosphorus for Algae and Aquatic Weeds.  Report of  the
     Water Chemistry Program, University of Wisconsin-Madison,
     July 1, 1971.  34 p.

Frey, D.G.  Wisconsin:  The Birge-Juday Era. In:  Limnology
     in North America.  Frey, D.G. (ed.). Madison, Wisconsin,
     University of Wisconsin Press. 1963.  p.3-54.

Huff, D.D., J.F. Koonce, W.R. Ivarson, P.R. Weiler, E.H. Dett-
     man, and R.F. Harris.  Simulation of Urban Runoff,  Nutrient
     Loading and Biotic Response of a Shallow Eutrophic  Lake.
     In:  Mode]ing the Eutrophication Process, Workshop
     Proceedings, ,"Nov. , 1973.  Middlebrooks , E . J . , D.H.  Falken-
     borg, and T.E. Maloney (eds.).  Utah State University, 1973,
     211 p.

Kluesener, J.W.  Nutrient Transport and Transformations  in
     Lake Wingra, Wisconsin.  Ph.D. Thesis, University of
     Wisconsin-Madison, 1972.  242 p.

Kluesener, J.W. and G.F. Lee.  Nutrient Loading from a Separate
     Storm Sewer in Madison, Wisconsin.  J. Wat. Pollut. Control
     Fed.  4j>_: 920-936, 1974.

Lee, G.F.  Ways in Which a Resident of the Madison Lakes'
     Watershed May Help to Improve Water Quality in the
     Madison Lakes.  Report of the Water Chemistry Program,
     University of Wisconsin-Madison.  1972.  10 p.

Lee, G.F. and J.W. Kluesener.   Nutrient Sources for Lake
     Wingra, Madison,  Wisconsin.   Report of the Water Chemistry
     Program, University of Wisconsin-Madison.   1971.   4 p.

Li, W.C., D.E. Armstrong, J.D.H.  Williams,  R.F.  Harris and
     J.K. Syers.   Rate and Extent of Inorganic Phosphate
     Exchange in Lake Sediments.   Soil Sci.Soc.  Amer.  Proc.
     ^£.-279-285,  1972.

Murray,  R.C.  Recent Sediments of Three Wisconsin Lakes.
     Bulletin of the Geological Society of America.   67 : 883-
     910, 1956.                                       ~

-------
Neess, J., W.T. Helm, and C.W.  Theinen.  Carp Census of Lake
     Wingra.  Cited in Kluesener, J.W.  Nutrient Transport
     and Transformations in Lake Wingra, Wisconsin.  Ph.D.
     Thesis, University of Wisconsin-Madison, p. 5, 1972.

Neess, J.C., W.T. Helm, and C.W. Theinen (1957).  Some Vital
     Statistics in a Heavily Exploited Population of Carps.
     Cited in Hasler, A.D.  Wisconsin, 1940-1961.  In:
     Limnology in North America.   Frey, D.G. (ed.).  Madison,
     Wisconsin, University of Wisconsin Press,  1963.p.71-72.

Noland, W.E. (1950) The Hydrography, Fish and Turtle Polulation
     of Lake Wingra.  Cited in Frey, D.G. Wisconsin:  The
     Birge-Juday Era.  In:  Limnology in North America.  .Frey,
     D.G. (ed.).  Madison, Wisconsin, University of Wisconsin
     Press.  1963. p.7.

Sonzogni, W.C.  Effect of Nutrient Input Reduction on the
     Eutrophication of the Madison Lakes.  Ph.D. Thesis,
     University of Wisconsin-Madison, 1974.  412 p.

Tressler, W.L. and B.P. Domogalla.  Limnological Studies of
     Lake Wingra.  Trans. Wise. Acad. Sci. Arts Lett.  26:331-
     351, 1931.

Twenhofel, W.H.  The Physical and Chemical Characteristics of
     the Sediments of Lake Mendota, A Fresh-Water  Lake of
     Wisconsin.  Jour. Sed. Pet.  3_: 68-76, 1933.

Vollenweider, R.A.  (1973)  Input-Output Models.  Schweiz. Z.
     Hydrol.  In'Press,

Vollenweider, R.A. and P.J. Dillon.  The Application of the
     Phosphorus Loading Concept to Eutrophication  Research.
     Environmental Secretariat, National Research  Council of
     Canada, NRC Associate Committee on Scientific Criteria
     for Environmental Quality.  Ottawa, Ontario,  Canada.
     Publication Number NRCC 13690.  1974.  42 p.

Walton, C.P. and G.F. Lee.  A Biological Evaluation of the
     Molybdenum Blue Method for Orthophosphate Analysis.
     Verh. Internat. Verein. Limnol.  18_: 676-684,  1972.

Williams, J.D.H., J.K. Syers, R.F. Harris, and D.E. Armstrong.
     Adsorption and Desorption of Inorganic Phosphorus by
     Lake Sediments in a 0.1 M NaCl System.  Environ. Sci.
     Tech. 4_:517-519,  1970.

Williams, J.D.H., J.K. Syers, S.S. Shukla, R.F. Harris, and
     D.E. Armstrong.  Levels of Native Inorganic and Total
     Phosphorus in Lake Sediments as Related to Other
     Sediment Parameters.  Environ. Sci. Tech.  5:1113-1120,
     1971.

                                372

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              REPORT ON NUTRIENT LOAD - EUTROPHICATION RESPONSE

              OF SELECTED SOUTH-CENTRAL WISCONSIN IMPOUNDMENTS


                      Marvin D. Piwoni and G. Fred Lee
                    Institute for Environmental Sciences
                       University of Texas at Dallas
                             Richardson, Texas
                                INTRODUCTION
     To meet an increasing demand for lakeside property in Wisconsin, private
developers constructed a number of recreational impoundments during the 1960's
and early 1970's.  In addition, state and local governmental agencies devel-
oped impoundments to provide water recreation for the public.  This report
assesses the relative water quality in ten impoundments in central and south-
ern Wisconsin through the development of a trophic state index.  The nutrient
loadings to each of the impoundments are estimated and a comparison made
between estimated nutrient load and trophic status for these impoundments.
This is accomplished by applying a phosphorus loading relationship developed
by Vollenweider (1973).
                            IMPOUNDMENTS STUDIED
     Rickert and Spieker (1971) have defined real estate lakes as bodies of
water created in an urban environment for the enhancement of real estate
value.  Wisconsin has experienced a large number of impoundments of this
type.  This study includes lakes created to facilitate high density lake
front development.  It also includes public recreation lakes which repre-
sent the other broad classification of impoundments investigated in this
study.  These are lakes created for various recreational uses of the public
and are free of significant urban development around the lake.  The impound-
ments investigated in this study can be divided into these two classifica-
tions as shown in Table 1.
                                     373

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       Table 1.   GENERAL CLASSIFICATION OF IMPOUNDMENTS
                 IN THIS STUDY
 Real Estate Lakes                 Public Recreation Lakes
 Lake Redstone                     Blackhawk Lake
 Lake Virginia                     Stewart Lake
 Dutch Hollow Lake                 Cox Hollow Lake
 Lake Camelot North                Twin Valley Lake
 Lake Camelot South
 Lake Sherwood

            GEOGRAPHIC AND HYDROLOGIC DESCRIPTION

The impoundments described in this report are all located in
central and southern Wisconsin (see Figure 1).  The Camelot-
Sherwood complex is located in central Wisconsin about ten
miles south of Wisconsin Rapids.   These three impoundments
are located on Spring Branch and  Fourteen-Mile Creeks which
drain marshy areas of the central sand plains.  Lakes Red-
stone, Virginia and Dutch Hollow, also located in the central
part of the state, are in Sauk County near Reedsburg.  Lakes
Redstone and Dutch Hollow were formed in dammed valleys of
Big and Dutch Hollow Creeks, respectively.  Lake Virginia is
a seepage lake, relying predominantly on groundwater to main-
tain the water level.
Three of the impoundments are located in Iowa County in the
southwestern part of the state.  Blackhawk Lake is located
north of the town of Cobb.  Two dams on adjacent valleys re-
sulted in a horseshoe-shaped lake.  Two inlet streams (total
average flow is about 4.4 cfs) provide water to the lake.
Cox Hollow and Twin Valley Lakes, in Governor Dodge State Park
north of Dodgeville, are interconnected by a  stream

                             374

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                            Figure I
     Impoundment Locations in Central and Southern Wisconsin
       N
     25 MILES
                                   \
     WISCONSIN
      RAPIDS.
PETENWELL
 FLOWAGE
 WISCONSIN
       7      8     • MADISON

       R>DGEV,U."MTHOREB
  COBB c
 KEY;
 I.CAMELOT-SHERWOOD COMPLEX
2. DUTCH HOLLOW LAKE
3.LAKE REDSTONE
4. LAKE VIRGINIA
                  [MILWAUKEE
5.BLACKHAWK LAKE
6.COX HOLLOW LAKE
7TWIN VALLEY LAKE
8.STEWART LAKE
                            375

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approximately one mile long.  Effluent waters from Cox Hollow
Lake flow into Twin Valley Lake.  Cox Hollow Lake was formed
by placing an earthen dike at the junction of two valleys,
creating a horseshoe-shaped lake.  The impoundment is equipped
with several artificial circulation devices to maintain dis-
solved oxygen in the hypolimnion during periods of stratifi-
cation.  Twin Valley Lake receives about one-half of its
normal water flow from Cox Hollow Lake.   Three other small
streams contribute to the 4 cfs average inflow.  The dam
structure of the impoundment is designed for withdrawal of
bottom waters from the impoundment.
Stewart Lake is located in southwestern Dane County near Mt.
Horeb.   The lake is fed by a small inlet stream and several
artesian springs.
The surface area, mean depth and hydraulic residence times
of the impoundments are summarized in Table 2.  All the impound-
ments are quite shallow, with surface areas ranging from
25,000 to 2.8 million square meters.  Hydraulic residence
times range from about one month to nearly three years.

                         CLIMATE
All of these impoundments are influenced by similar climato-
logical conditions.  Annual average temperatures range from
40 to 50°F.  In January, average temperatures are 15-20°F,
while in July the average temperature is about 70-75°F.  An
ice cover forms on the impoundments in early to mid-December
and generally persists into early April.
Annual precipitation averages near 30 inches with much of the
precipitation falling from April through September.  Average
annual snowfall ranges from 35-50 inches, with the larger
accumulations occurring further north in the state.  Based on
studies of other lakes in this region of the state (Cline,
1965),  the evapotranspiration is probably about equal to the
precipitation.
                           376

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         Table 2.  HYDROLOGICAL CHARACTERISTICS
                   OF THE IMPOUNDMENTS*

Surface
9Area5[;
Impoundment
Camelot-
Sherwood
Redstone
Dutch Hollow
Virginia
Blackhawk
Cox Hollow
Twin Valley
Stewart
m X

28
25
8
1
8
3
6
0
10

.3
. 3
.5
. 8
.9
.9
.1
.25
Mean

2
4
6
1
4
3
3
1
Depth, m

.9
.3

.7
.9
.8
.8
.9
Hydraulic
Residence
Years

0.09 - 0.
0.7 - 1
1.8
0.6 - 1.
0.5
0.5 - 0.
0.4 - 0.
0.08
Times ,


14


9

7
5

* Information in this table was obtained from the lake devel-
  opers or from Wisconsin DNR files (1972-73) and previously
  appeared in Piwoni and Lee (1974).  Certain mean depth and
  hydraulic residence time values have been subsequently re-
  vised.  All data are for projected normal pool elevations.

                         GEOLOGY

The Camelot-Sherwood basin is set into an area of unconsoli-
dated morainal deposits composed of glacial till and gravel
and sand outwash (Weeks and Strangland, 1971).  These deposits
are underlain by Cambrian sandstone over Precambrian crystal-
line rock.  The unconsolidated deposits are the major source
of water to the region.
Similar geology likely extends to the Reedsburg area (Lakes
Virginia, Redstone and Dutch Hollow), although no specific
information is available.
                           377

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The Twin Valley-Cox Hollow basin contains a number of water-
bearing geologic formations (Klingelhoets,  1962).  These in-
clude Galena dolomite, Platteville limestone and St. Peter
sandstone, all yielding small amounts of high mineral content
water.  Soils in the region are composed of silty loam and
loamy alluvial materials with high organic  content.  Much of
the area surrounding the impoundments is quite steep and
rocky.
The geology of the Blackhawk Lake watershed is probably quite
similar to Cox Hollow and Twin Valley watersheds.  The water-
shed is located in the driftless region of  the state and
consists of narrow ridges with steep, narrow V-shaped valleys
(Bredemus, 1970).  The soil regime is composed of silty loam
and stony undeveloped soils.
The Stewart Lake watershed consists of deposits of Trenton and
Galena limestones and St. Peter sandstone (WDNR, 1972-73).
The soils in the region are predominantly silty loam and sandy
loam with some stony land.

                   WATERSHED CHARACTERISTICS

All of the impoundments are in rural, predominantly agricul-
tural watersheds (except for Stewart Lake,  which is located
below a small city and receives much of the runoff from the
city streets).  The real estate lakes will  likely undergo
changes in nutrient loadings from the watershed as develop-
ment of waterfront homes (with septic tank systems) proceeds.
Table 3 presents the areas of the watershed of each impound-
ment.   The range of watershed size is from 510 acres for
Stewart Lake to over 22,000 acres for the Camelot-Sherwood
Complex.
                              378

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          Table 3.  AREA OF IMPOUNDMENT WATERSHEDS*

Impoundment
Camelot- Sherwood
Redstone
Dutch Hollow
Virginia
Blackhawk
Cox Hollow
Twin Valley
Stewart
Acres
22,400
18,940
3,100
1,600
8,960
3,970
7,680
510
Hectares
9,060
7,660
1,250
650
3,630
1,610
3,110
210
* Information in this table was compiled from lake developer
  data, data from the Wisconsin DNR files (1972-73) and from
  USGS topographic maps.  This information is based on
  Piwoni and Lee (1974).
                   BIOLOGICAL DESCRIPTION
FISHERIES
Limited information was available on the fisheries of several
of the impoundments.  Attempts have been made to manage the
fisheries in nearly all of the impoundments.  Consequently,
stocking of various game fishes has taken place over the
years.  However, the fisheries in nearly all of the impound-
ments are predominantly composed of panfish such as the blue-
gill (Lepomis macrochirus) and sunfish (Lepomis spp.),plus a
number of rough bottom feeding fish.  Fishing time,and con-
sequently fish yields , has generally dropped in recent years,
presumably because of an overabundance of small panfish
varieties instead of more favored gamefish.
Lake Redstone has been stocked several times with walleye
(Stizostedion vitreum) to supplement existing fish populations
(Smith, 1973).  The lake also contains apparently declining
                             379

-------
populations of largemouth bass (Micropterus salmoides) and
northern pike (Esox lucius).   Walleye and panfish appeared to
be stunted in growth probably due to reduced living space
indirectly caused by reduced DO levels in the hypolimnion
during winter and summer.
Reports by Dunst (1969) and Wirth  et al. (1970) indicate
that similar fish species inhabit Cox Hollow and Twin Valley
Lakes.  Largemouth bass and northern pike were stocked in
Cox Hollow Lake in 1958 (Dunst, 1969).> but populations gener-
ally decreased after 1962.  Records on these two fishes in
Twin Valley Lake (Wirth  ejt al. , 1970) indicated both species
suffered from a 60-70 percent mortality rate.  Smaller sized
bluegills were beginning to dominate the fish populations.
feiibow trout have been stocked in Stewart Lake and seem to
grow well although reproduction information was not available.
Annual opening day trout fishing is quite heavy on this
impoundment (with reportedly good results)

AQUATIC PLANTS
Very little information was available on specific macrophyte
populations in these impoundments.  All of the impoundments
suffered from excessive macrophyte growth in littoral areas.
Impoundments with steep banks, such as Redstone, Blackhawk,
and Twin Valley, did not have the problems prevalent in
impoundments with large littoral regions such as the Camelot-
Sherwood complex.  The latter was treated annually with her-
bicide to control aquatic weeds.
Dunst (1969) reported that Ceratophyllum demersum had become
the dominant macrophyte in Cox Hollow Lake.  That plant, as
well as Myriophyllum, Potamogeton and Limna spp. , was observed
by the authors in the Camelot-Sherwood complex.  Stewart Lake
supported a variety of aquatic vegetation in the shallow
waters near the point of inflow of the creek,including
                              380

-------
cattails, water lilies, wild rice and sedges.  Macrophyte
problems were not critical in any of the other impoundments
sampled during a two year period from June, 1971 to April,
1973 (Piwoni and Lee, 1974).
Blue-green algae obtained dominance in all of the impound-
ments at least on two occasions during the summers of 1971
and 1972 (Piwoni and Lee, 1974).  Anacystis spp. attained
dominance at least once in all the impoundments except Lake
Virginia.  Aphanizomenon, C_oe la strum and Anabaena spp. were
other predominant blue-greens.  In Lake Virginia, Scenedesmus
was the dominant algal genus on several sampling dates. Dur-
ing spring and fall, algal populations in the impoundments were
dominated by diatoms, such as Fragilaria and Asterionella,
and flagellates, such as Trachelamonas and Ch1amydomonas.
The amount of algae is reflected in chlorophyll a concentra-
tions presented later in this paper.
        TROPHIC INDEX PARAMETERS AND ANALYSIS METHODS
To assess the water quality of the impoundments, a trophic
state index (TSI) was developed.  The approach employed is
similar to that used by Lueschow et_ al.  (1970) in their evalu-
ation of Wisconsin lakes.  The index parameters were chosen
because it was felt that they would present a relative indi-
cation of water quality in the impoundments.  While the over-
all approach is approximately the same,  there are important
differences between the formulation and use of the different
parameters in this evaluation and in the trophic state index
used by Lueschow et al. (1970) in their studies.
The trophic state index parameters used in this study are pre-
sented in Table 4.  Secchi depth measurements were used as a
measure of turbidity and light penetration (Ruttner, 1965).
Chlorophyll a., an estimate of the phytoplankton biomass, was
determined using the method described by Strickland and Parsons
(1965).  The percentage of the lake volume containing less than
                              381

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         Table 4.   TROPHIC STATE INDEX PARAMETERS
1.  Secchi Depth            - Mean of all values obtained.
2.  Chlorophyll a           - Average concentration in first
                              2 meters of water column dur-
                              ing study period.
3.  DO Depletion            - Percent of lake volume with
                              less than 0.5 mg-DO/1; May to
                              October, inclusive.
4.  Orthophosphate - winter - Average in-lake concentration
                              during winter under ice.
5.  Orthophosphate - summer - Average epilimnion concentra-
                              tion; May to October, inclusive.
6.  Total phosphorus -      - Average in-lake concentration
    winter                    during winter under ice.
7.  Total phosphorus -      - Average epilimnion concentra-
    summer                    tion; May to October, inclusive.
8.  Organic Nitrogen        - Average concentration in first
                              2 meters of water column during
                              study period.

0.5 mg/1 of dissolved oxygen gave an indication of the aquatic
plant material that accumulated in the hypolimnion and exerted
an oxygen demand.  DO was determined using a YSI Model 54 Dis-
solved Oxygen Meter.  All phosphorus determinations were made
using the ascorbic acid method described in Standard Methods,
13th edition (APHA et_ al., 1971).  Total phosphorus determina-
tions were made on unfiltered, autoclaved samples which were
treated with persulfate.  Ammonium and Kjeldahl-nitrogen analy-
ses were automated using a Technicon AutoAnalyzer and the
phenate method as described in Standard Methods  (APHA et_ al.,
1971).  Organic-N was calculated as Kjeldahl-N minus NH -N.
All nitrogen and phosphorus values are reported as mg-N/1 and
mg-P/1.  The atomic ratio of inorganic-N to soluble ortho-P
was in excess of 16 to 1 in all the impoundments except
Lake Virginia and, therefore, nitrogen apparently was not
                            382

-------
limiting algal growth.  Consequently, inorganic-N was not
included as a trophic state index parameter since the algal
growth in these impoundments was probably not dependent on
the inorganic-N concentration.
Samples used for analysis were collected over a two-year
period at approximately six week intervals.  Samples were
collected at either one or two meter intervals in the deepest
part of the impoundments.  Volumn-weighted mean lake concen-
trations of the parameters in Table 45 excluding Secchi depth
and DO depletion, were calculated for each sampling date.
The mean values for the index parameters for each of the im-
poundments were then determined.  These values are presented
in Table 5, along with the trophic ranking received by the
impoundments for each parameter.  This ranking was based on a
relative scale in which each impoundment was assigned an integer
value from 1 to 10 dependent on the relative magnitude of each
of its water quality-TSI parameters.  For example, Blackhawk
Lake had the highest average Secchi depth.  It was ranked
number 1 for this parameter.  Dutch Hollow Lake had the lowest
average Secchi depth and was ranked number 10.  The sum of
these individual parameter rankings yielded an overall trophic
state index value for each lake.  Inorganic-N was not used to
compute this sum.  These values provided the basis for the
water quality ranking of the impoundments given in Table 6.
The complete data obtained in this investigation have been
reported by Piwoni and Lee (1974).
Lakes Camelot North and South and Sherwood received the high-
est water quality rankings (see Table 6).  These lakes were
arbitrarily designated as moderately eutrophic based on the
TSI value and general water quality characteristics.   The
reasons for the relatively high water quality in these lakes
is probably because of the low in-lake  phosphorus levels and
the highly-colored nature of the water.   The latter can limit
algal growth by limiting light penetration (Lee, 1972).
                            383

-------
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-------
       Table 6.  WATER QUALITY RANKING OF IMPOUNDMENTS
                 BASED ON TROPHIC STATE INDEX
 Relative Degree
of Eutrophication
Moderate








High
Rank
1
2
3
4
5
6(tie)
6
8
9
10
Lake
Camelot North
Sherwood
Camelot South
Redstone
Stewart
Blackhawk
Twin Valley
Cox Hollow
Virginia
Dutch Hollow
TSI*
11
18
26
41
45
53
53
54
55
67
* Trophic State Index Value.  This value is the sum of the
  individual parameter relative rankings in Table 5.

Lakes Redstone through Virginia  have similar water quality
problems and TSI values.  Dutch Hollow Lake, which had severe
algal and turbidity problems throughout most of the study, was
designated as highly eutrophic.
Algal and macrophyte growth produces some aesthetic problems
in all these impoundments and can hamper establishment of game
fisheries.  Most of the impoundments, which have occasional
excessive algal blooms and macrophyte growth provide water-
related recreational activities for large numbers of people
and, therefore, are important recreational assets to the
area.
Water quality in most of these impoundments should be quite
stable, except perhaps in the newest lakes, Blackhawk and
Dutch Hollow, where water quality is likely to improve with
                             385

-------
time (Frey, 1963).  In the real estate lakes, which will ex-
perience continued development over the next 20-50 years
(Carlson, 1971), it is possible that some deterioration of
water quality could result as nutrients from septic tank
effluents enter the lake.   The significance of this potential
source of nutrients would have to be evaluated in light of
the total nutrient loadings to the lakes and the amount of
phosphorus that enters the lakes from this source.

                    NUTRIENT LOADINGS
Nutrient loadings for all the impoundments were estimated from
land use in the watershed using the values Sonzogni and Lee
(1974) developed for the Lake Mendota (Wisconsin) watershed.
These values are presented in Table 7.  The only variation in
the table values applied in the study was for total-P from
rural runoff.  The range of 0.34 to 0.45 kg/ha/yr was used
because these values correlated most closely with a nutrient
input study on Cox Hollow Lake performed by Dunst et al. (1972).
Information on lake and watershed characteristics was obtained
from the Wisconsin Department of Natural Resources and lake
development personnel.  The loadings, calculated as kg/year
       2
and g/m  of surface area, are presented for each impoundment
in Table 8.  Ranges reflect the range used for contribution of
P from rural lands.  Available information on the watershed re-
quired grouping Lake Camelot North and South and Sherwood.
Groundwater was not included in the estimates of nutrient load-
ings because of the difficulties of evaluating the relative
importance of this potential nutrient source.  Groundwater
would be expected to supply considerable amounts of nitrogen,
and possibly some phosphorus, particularly in sandy soil regions
The omission of the groundwater component is thought to be of
minor importance based on studies conducted by Lee (1972).
Vollenweider (1973) had developed a logarithmic plot relating
phosphorus loading to mean depth/hydraulic residence time.
This graph also contains straight-line definitions of "per-
missible" and "excessive" phosphorus loading limits relative
                            386

-------
    Table 7.  AMOUNTS OF NITROGEN AND PHOSPHORUS DERIVED
              FROM VARIOUS TYPES OF LAND USE
              DANE COUNTY, WISCONSIN*

Amounts Contributed
(kg/hectare/yr)
Activity
Base Flow
Woodland
Rural Runoff
Inorganic -N
1.2
0
3.1
Organic-N Soluble 0-P Total-
0.11 0.11
0 00
P


2.0 0.34 0.67**
0.22***
Urban Runoff          1.1

Manured lands
 100 cows/sq.mi.
 15 tons manure/year

Precipitation         6.0

Dry Fallout           7 . 5

Domestic Waste-
 waters               2.7

Septic Tanks          var.

Groundwater           var.

Drained marshes
        3.9


        3.4


        1.9
0.67
0.18

0.11
        8.1

      (kg/capita/yr)
        0.9         1.4
        var.

        var.
var.

var.
1.1


1.1


0.22

0.78


2.0

var.

var.
101 kg/hectare
   45 kg/hectare
*    After Sonzogni and Lee (1974)
**   Wisconsin
***  Other Areas
                              387

-------
    Table 8.  NUTRIENT LOADINGS TO THE IMPOUNDMENTS5'5

Nitrogen
Impoundment
Redstone
Dutch Hollow
Virginia
Camelot -Sherwood
Blackhawk
Stewart
Cox Hollow
Twin Valley
kg
45
8
3
97
20
1
7
10
/year
,400
,800
,300
,600
,900
,850
,410
,500
Loading
Phosphorus
Loading
g/m^ kg/year
18
10
18
34
23
73
19
17
.1
.4
.3
.6
.4
.6
.1
.4
3630-42
810-
210-
30
870
2
6660-75
1.900-2
120-
630-
1090-1
0
2
70
80
70
00
810
250
1
0
1
2
2
4
1
1
g/m
.44-1
.95
.15
.35
-1
-1
-2
.11-2
.82
.62
.74
-8
-2
-2
2
.68
.02
.48
.68
.32
.05
.08
.05
" Date are revised from earlier values presented by Piwoni and
  Lee (1974).  Loadings are presented as total kg/year and as
  grams per square meter of lake surface area.
to depth-flushing characteristics of the lake.  The necessary
calculations were made to determine values of mean depth/hy-
draulic residence times for each of the study impoundments.
                                        2
Annual total phosphorus loadings, in g/m , were then plotted
against the mean depth/hydraulic residence time values , in
m/yr, on a reproduction of the Vollenweider plot (Vollenweider,
1973) (Figure 2).
All of the impoundments fell into the region of the graph
defined by Vollenweider (1973) to be eutrophic.  The degree
of eutrophication was interpreted as the "distance" a specific
lake was above the "permissible" loading level for a lake with
the same mean depth/hydraulic residence time value.  Table 9
presents the estimated phosphorus loading and the "permissible"
loading level, as defined by Vollenweider (1973), for each of
                            388

-------
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of the impoundments.  It also gives the ratio of estimated
loading to  "permissible" phosphorus loading.  This ratio
should be an indication of the degree of eutrophication of
each impoundment.  The impoundments were arranged in Table 9
in order of ascending mid-range ratio values, i.e., in decreas-
ing lake water quality based on this loading ratio.
Dutch Hollow Lake was filling throughout the study period;
this is reflected in the ranking in Tables 6 and 9 and indi-
cates the lake water quality would improve when the lake was
filled.  Blackhawk was also filling throughout the first eight
months of the study; however, normal pool elevation was used
in all calculations presented here.
Comparison of the water quality ranking in Table 6 with that
in Table 9 shows reasonably good correlation particularly at
the ends of the ranking scale.  Several of the impoundments
have exchanged positions in the order in Table 9 , but these
lakes generally have overlapping phosphorus loading ratio
ranges.  Part of the problem for a lack of correlation between
estimated total phosphorus loads and the overall water quality
characteristics may be due to a number of factors.  One of
these is that in some instances a substantial part of the total
phosphorus, such as the particulate forms, entering the im-
poundment may not become available to aquatic plants in the
impoundment.  Studies by Cowen (1973) show that only about
30 percent of the particulate phosphorus in both urban and
rural drainage will likely become available for algal growth
in lakes.
It appears that either approach to assessing relative water
quality in lakes and impoundments is viable, and together they
may provide an approach to lake water quality assessment and
management.
A number of hydrologic and water quality parameters for each
lake are summarized in Tables A-l to A-8 in the Appendix.
                             391

-------
                       ACKNOWLEDGEMENTS

Most of the information in this report was taken from Piwoni
and Lee (1974) Report to the Wisconsin Department of Natural
Resources.  That report was assembled as part of a Master's
thesis study at the University of Wisconsin-Madison.  Copies
of the report may be obtained by writing the authors.  Pre-
sentation of much of the background information on these im-
poundments would not have been possible without the assist-

ance of the Wisconsin Department of Natural Resources per-
sonnel, especially T. Wirth and R. Dunst, and several of the

lake developers.  Special thanks also go to J. Stroud for

his assistance throughout the project.


                        REFERENCES
American Public Health Association, American Water Works
     Association, Water Pollution Control Federation.
     Standard Methods for the Examination of Water and
     Wastewater, 13th ed., New York, APHA, 1971.   874  p.

Bredemus,  R.N.  Fish Habitat Development Project  Proposal
     for Blackhawk Lake.  Wise. Dept.  Natural Res. Report,
     Madison, Wise., June 5, 1970.

Carlson, K.  Personal Communication to G.F.  Lee.   Building
     Development Report, Madison, Wise.  1971.

Cline ,  D.R.  Geology and Groundwater Resources of Dane
     County, Wise.  USGS Water-Supply Paper 1779-U.
     1965.  64 p.

Cowen,  W.F., K. Sirisinha and G.F.  Lee.   Nitrogen Availability
     in Lake Ontario Tributary Waters During IFYGL, Pres. 17th
     Conference Great Lakes Research, 1974.

Dunst,  R.C. Cox Hollow Lake, The First Eight Years of  Im-
     poundment.  Wise. Dept. Natural Res. Research Project
     47.  Madison, Wisconsin.  1969.  19 p.

Dunst,  R.C., T.L. Wirth and P.D. Uttormark.   Cox  Hollow Lake
     Nutrient Supply and Retention, Wise. Dept. Natural Res.
     Madison, Wisconsin, 1972.

Frey, D.G. (ed.).  Limnology in North America. Madison,  Wise.
     University of Wise.  Press, 1963.  p.  575-593.

Klingelhoets, A.J.  Soil Survey of Iowa County, Wisconsin.
     Soil  Conservation Ser.  1958,  No. 22, 1962.   100  p.

                             392

-------
 Lee,  G.  F.   Expected Water  Quality  in  the N.E.   Isaacson
    and  Associates  Proposed Impoundment  on  Fourteen  Mile
    Creek-Adams  County, Wisconsin.   Report  to N.  E.
    Isaacson and Associates.   1972.

 Lueschow, L. A., J. M. Helm, D. R. Winter, and G. W. Karl.
    Trophic  Nature of Selected Wisconsin Lakes.   Trans.
    Wise. Acad.  Sciences, Arts and Letters. 58:  247-264,
    1970.

 Piwoni, M. D. and G. F. Lee.  A Limnological Survey  of
    Selected Impoundments in Central and Southern Wis-
    consin.  Report to Wise. Dept. Natural Res.  May 1974.

 Rickert, D. A. and A. M. Spieker.  Real-Estate Lakes.  USGS
    Circ. 601-G.  Washington, D. C.  1971.  19 p.

 Ruttner, F.  Fundamentals of Limnology.  Toronto, University
    of Toronto Press, 1965.   p. 14-15.

 Smith, T.  Lake  Inventory,  Lake Redstone, Sauk County.
    Report to C. Enerson, Wise. Dept. Natural Res., Dodge-
    ville, Wise.  1973.

 Sonzogni, W. C. and G.  F. Lee.  Nutrient Sources for Lake
    Mendota — 1972.  Trans. Wise. Acad. Sciences, Arts
    and Letters. ^2: 133-164,  1974.

 Strickland, J. D. H. and T.  R. Parsons.  A Manual of Sea
    Water Analysis, 2nd Ed.   Ottawa, Fisheries Research
    Board of Canada. 1965.  p. 1B5-192.

 Vollenweider, R. A. (1973).   Input-Output Models.  Schweig.
    Z. Hydrol.  In Press.

Weeks, E. P. and H. G.  Strangland.  Effects of Irrigation
    on Streamflow in the Central Sand Plain of Wisconsin.
    USGS Open File Report, Madison, Wise. 1971.   p. 18-29.

Wirth, T. L., R. C. Dunst, P. D. Uttomark, and W. Hilsen-
    hoff.  Manipulation of Reservoir Waters for Improved
    Quality and Fish Population Response.  Wise. Dept.
    Natural Res. Research Rpt. 62, Madison, Wise. 1970.
    23 p.

Wisconsin Department of Natural Resources (WDNR) Files,
    Madison, Wise., 1972-73 .   Much of this material was
    undated and in loose form.  Material was obtained
    through the courtesy of T. Wirth and R. Dunst.
                            393

-------
    TABLE A-l DATA SUMMARY FOR NORTH AMERICAN PROJECT
              LAKE REDSTONE (WISCONSIN)
Trophic State
Lake Type
Drainage Area
Lake Surface Area
Mean Depth
Retention Time
Mean Alkalinity
Mean Conductivity
Mean Secchi Disk
Mean Dissolved Phosphorus
Mean Total Phosphorus
Mean Inorganic Nitrogen
Mean Chlorophyll a
Annual Productivity
Phosphorus Loading
 Point source
 Non-point source
 Surface area loading
Nitrogen Loading
 Point source
 Non-point source
 Surface area loading
Eutrophic
Impoundment
         7
7.67 x 10  square meters
2.52 x 10  square meters
4.3 meters
0.7-1 years
125 mg/1 as CaC03
260 umhos/cm @ 25°C
1.6 meters
0.008a'b mg/1 as P
0.03a O.llb mg/1 as P
0.80a 0.31b mg/1 as N
12.8° pg/l
0 kg/year
3630 - 4230 kg/year ,
1.44 - 1.68 gr/meter /year

0 kg/year
45,400 kg/yea^1
18.1 gr/meter /yr
 Average winter
b,                . , .
 Average sunder epilimnion
/-^
 In first two neters of water column
--Not determined
                            394

-------
     TABLE  A-2  DATA  SUMMARY FOR NORTH AMERICAN PROJECT
               DUTCH HOLLOW LAKE (WISCONSIN)
Trophic  State
Lake Type
Drainage Area
Lake Surface Area
Mean Depth
Retention Time
Mean Alkalinity
Mean Conductivity
Mean Secchi Disk
Mean Dissolved Phosphorus
Mean Total Phosphorus
Mean Inorganic Nitrogen
Mean Chlorophyll a
Annual Productivity
Phosphorus Loading
 Point source
 Non-point source
 Surface area loading
Nitrogen Loading
 Point source
 Non-point source
 Surface area loading
- Eutrophic
- Impoundment
           7
- 1.25 x 10  square meters
- 8.50 x 10  square meters
- 3 mCstudy level)-  6 mCwhen
  , D                  filled)
- 1.8 years
- 133 mg/1 as CaC03
- 25? pmhos/cm @ 25°C
- 0.8 jneters
- 0.021a 0.013b mg/1 as P
- 0.40a  0.12b  mg/1 as P
- 0.61a  0.22b  mg/1 as N
- 33.9° pg/1
  0 kg/year
  810 - 870 Kg/year
  0.95 - 1.01 gr/meter /year
  0 kg/year
  8,800 kg/year2
  10.4 gr/meter /year
 Average winter
 Average summer epilimnion
 In first two meters of water column
--Not determined
                             395

-------
    TABLE A-3 DATA SUMMARY FOR NORTH AMERICAN PROJECT
              LAKE VIRGINIA (WISCONSIN)
Trophic State
Lake Type
Drainage Area
Lake Surface Area
Mean Depth
Retention Time
Mean Alkalinity
Mean Conductivity
Mean Secchi Disk
Mean Dissolved Phosphorus
Mean Total Phosphorus
Mean Inorganic Nitrogen
Mean Chlorophyll a
Annual Productivity
Phosphorus Loading
 Point source
 Non-point source
 Surface area loading
Nitrogen Loading
 Point source
 Non-point source
 Surface area loading
- Eutrophic
- Impoundment
- 6.48 x 10  square meters
- 1.82 x 10  square meters
- 1.7 meters
- 0.9 - 2.8 years
- 64 mg/1 as CaCOQ
                 J
- 230 umhos/cm at 25 C
- 1.2 meters
- 0.004a 0.025b mg/1 as P
- 0.02a  0.15b mg/1  as P
- 0.22°  0.18U mg/1  as N
- 29.0C yg/1
  0 kg/year
  210 - 270 kg/year   2
  1.15 - 1.U8 gr/meter /year

  0 kg/year
  3,300 kg/year2
  18.3 gr/meter /year
 Average winter
b.                ., .
 Average summer epilimnion
cln first two meters of water column
--Not determined
                            396

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    TABLE A-4  DATA  SUMMARY FOR NORTH AMERICAN PROJECT
               CAMELOT-SHERWOOD COMPLEX  (WISCONSIN)
Trophic State
Lake Type
Drainage Area
Lake Surface Area
Mean Depth
Retention Time
Mean Alkalinity
Mean Conductivity
Mean Secchi Disk
Mean Dissolved Phosphorus
Mean Total Phosphorus
Mean Inorganic Nitrogen
Mean Chlorophyll a_
Annual Productivity
Phosphorus Loading
 Point source
 Non-point source
 Surface area loading
Nitrogen Loading
 Point source
 Non-point source
 Surface area loading
- Mesotrophic - Eutrophic
- Impoundment
           7
- 9.06 x 10  square meters
- 2.83 x 10  square meters
~ 2.9 meters
- 0.09 - 0.14 years
-125 mg/1 as CaCOg
- 311 ym^ios/cm at 25 C
- 2.0 meters
- 0.008a  0.008b mg/1 as P
- 0.03a   0.04b  mg/1 as P
- 1.07a   0.59b  mg/1 as N
- 6.3C Ug/1
  0 kg/year
  6660 - 7580 kg/year
  2.35 - 2.68 gr/meter /year
  0 kg/year
  97 ,600 kg/year
  34.6 gr/meter2/year
 Average winter
 Average surfer epilimnion
°In first two meters of water column
--Not determined
                             397

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    TABLE A-5 DATA SUMMARY FOR NORTH AMERICAN PROJEC
              LAKE BLACKHAWK (WISCONSIN)
Trophic State
Lake Type
Drainage Area
Lake Surface Area
Mean Depth
Retention Time
Mean Alkalinity
Mean Conductivity
Mean Secchi Disk
Mean Dissolved Phosphorus
Mean Total Phosphorus
Mean Inorganic Nitrogen
Mean Chlorophyll a_
Annual Productivity
Phosphorus Loading
 Point source
 Non-point source
 Surface area loading
Nitrogen Loading
 Point source
 Non-point source
 Surface area loading
- Eutrophic
- Impoundment
- 3.63 x 10  square meters
- 8.90 x 10  square meters
- 4.9 meters
- 0.5 years
- 227 mg/1 as CaC03
      umhos/cm at 25°C
- 3.6 meters
- 0.044°  0.015b mg/1 as P
- 0.12a   0.05b  mg/1 as P
- 1.02a   0.54b  mg/1 as N
- 14.6° pg/l
  0 kg/year
  1900 - 2070 kg/year 2
  2.13 - 2.32 gr/meter /year
  0 kg/year
  20,900 kg/year
  23.4 gr/meter^/year
 Average winter
 Average summer epilimnion
Q
 In first two meters of water column
--Not determined
                             398

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    TABLE A-6 DATA  SUMMARY FOR NORTH AMERICAN PROJECT
              LAKE  STEWART (WISCONSIN)
Trophic  State
Lake Type
Drainage Area
Lake Surface Area
Mean Depth
Retention Time
Mean Alkalinity
Mean Conductivity
Mean Secchi Disk
Mean Dissolved Phosphorus
Mean Total Phosphorus
Mean Inorganic Nitrogen
Mean Chlorophyll a_
Annual Productivity
Phosphorus Loading
 Point source
 Non-point source
 Surface area loading
Nitrogen Loading
 Point source
 Non-point source
 Surface area loading
- Eutrophic
- Impoundment
- 2.07 x 10  square meters
           4
- 2.51 x 10  square meters
- 1.9 meters
- 0.08 years
- 213 mg/1 as CaCOg
- 540 Umhos/cm @ 25°C
- 1.4 meters
- 0.0113  0.008b mg/1 as  P
- 0.04a   0.08b  mg/1 as  P
- 2.26a   0.86b  mg/1 as  N
- 12.3° ug/1
  0 kg/year
  121 - 202 kg/year   2
  4.82 - 8.05 gr/meter /year

  0 kg/year
  1,850 kg/year2
  73.6 gr/meter /year
 Average winter
 Average suruner epilimnion
Q
 In first two meters of water column
--Not determined
                             399

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    TABLE A-7 DATA SUMMARY FOR NORTH AMERICAN PROJECT
              COX HOLLOW LAKE (WISCONSIN)
Trophic State
Lake Type
Drainage Area
Lake Surface Area
Mean Depth
Retention Time
Mean Alkalinity
Mean Conductivity
Mean Secchi Disk
Mean Dissolved Phosphorus
Mean Total Phosphorus
Mean Inorganic Nitrogen
Mean Chlorophyll a
Annual Productivity
Phosphorus Loading
 Point source
 Non-point source
 Surface area loading
Nitrogen Loading
 Point source
 Non-point source
 Surface area loading
- Eutrophic
- Impoundment
           7
- 1.61 x 10  square meters
- 3.88 x 10  square meters
- 3.8 meters
- 0.5 - 0.7 years
- 205 mg/1 as CaCO
- 440 umhos/cm @ 25°C
- 1.5 meters
- 0.036a  0.015b mg/1 as  P
- 0.10a   0.06b  mg/1 as  P
- 0.83a   0.36b  mg/1 as  N
- 26.5C pg/1
  0 kg/year
  630 - 810 kg/year   2
  1.62 - 2.08 gr/meter /year

  0 kg/year
  7,410 kg/year2
  19.1 gr/meter  /year
 Average winter
 Average surfer epilimnion
CIn first two meters of water column
--Not determined
                             400

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    TABLE A-8 DATA SUMMARY FOR NORTH AMERICAN PROJECT
              TWIN VALLEY LAKE (WISCONSIN)
Trophic State
Lake Type
Drainage Area
Lake Surface Area
Mean Depth
Retention Time
Mean Alkalinity
Mean Conductivity
Mean Secchi Disk
Mean Dissolved Phosphorus
Mean Total Phosphorus
Mean Inorganic Nitrogen
Mean Chlorophyll a.
Annual Productivity
Phosphorus Loading
 Point source
 Non-point source
 Surface area loading
Nitrogen Loading
 Point source
 Non-point source
 Surface area loading
- Eutrophic
- Impoundment
           7
- 3.11 x 10  square meters*
- 6.07 x 10  square meters
- 3.8 meters
- 0.4 - 0.5 years
- 175 mg/1 as CaCOg
- 370 ymhos/cm @ 25°C
- 1.5 meters
- 0.019a  0.009b mg/1 as P
- 0.07a   0.06b  mg/1 as P
- 0.51a   0.23b  mg/1 as N
- 19.0° yg/1
  0 kg/year
  1090 - 1250 kg/year 2
  1.7U - 2.05 gr/meter /year

  0 kg/year
  10,500 kg/year
  17. U gr/meter2/year
* About 1/2 of drainage area is controlled by an upstream
  impoundment.
aAverage winter
 Average summer epilimnion
cln first two meters of water column
—Not determined
                            401

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     SECTION VIII - MULTIPLE-STATE LAKES AND SPECIAL TOPICS
       LIMNOLOGICAL CHARACTERISTICS  OF THE POTOMAC ESTUARY
                          N.  A.  Jaworski
           Corvallis Environmental Research Laboratory
               U.S.  Environmental Protection Agency
                        Corvallis, Oregon
                           INTRODUCTION
     Increasingly, over the past few centuries, the water of the
Potomac Estuary has been degraded, primarily by the domestic
wastewater discharged from the Washington, D.C. metropolitan
area.  High coliform counts, low dissolved oxygen levels, and
nuisance algal growths typify water quality management problems
in the Potomac Estuary.


     Since the early 1900's, numerous water quality studies have
been conducted on the Potomac River Basin including the Estuary.
Initial studies primarily emphasized bacterial quality and dis-
solved oxygen problems.  Beginning in the late 1960's, studies
were expanded to include the problem of eutrophication.  A report
on the "Water Resources/Water Supply" by Jaworski, et al. (1971)
culminated over six years of intensive investigation of the Upper
Potomac Estuary.


     The Potomac Estuary was included in the North American
Project, a eutrophication study by the Organization of Economic
Cooperation and Development (OECD).  This report summarizes
history and recent data relative to the goals of the North Amer-
ican Project of OECD.
                               402

-------
             DESCRIPTION OF THE POTOMAC RIVER BASIN
The Potomac River Basin, including the Estuary, comprises the
second largest watershed in the Middle Atlantic States, with a
                                                           2
drainage area of approximately 38,000 square kilometers (km ).
From its headwaters on the eastern slope of the Appalachian
Mountains, the Potomac flows first northeasterly and then gen-
erally southeasterly some 644 km, flowing past the nation's
capital.  The Potomac is tidal from Washington, D. C. to its
confluence with the Chesapeake Bay, a distance of 183 km (Figure 1)
Of the 3.3 million people living in the basin, about 2.8 million
live in the Washington, D. C. metropolitan area.  The upper basin
is largely rural with scattered small cities populated by 10,000
to 20,000.  Land use in the entire Potomac Basin is estimated to
be 5 percent urban, 55 percent forest, and 40 percent agriculture,
including pasture lands.

Climate Study Area
The Potomac River Tidal System lies in a sort of climatic cross-
roads.  Cold air masses invade from Canada and the Arctic, while
the Appalachian Mountains provide some protection from the cold.

Hurricanes moving north along the Atlantic Seaboard generally pass
over the lower tidal system about once every five years.  Coastal
"northeastern" storms often bring strong winds accompanied by heavy
rain or snow from that direction, most frequently in winter and
early spring.

Annual precipitation ranges from 89 to 114 centimeters (cm), in-
cluding about 61 cm of snow.  Table 1 shows that precipitation is
fairly well distributed throughout the year.
                                 403

-------
CHA.N
                         , D.C.
                -WOODROW WILSON  .._„.__ „„ -. .
                     BRIDGE      UPPER REACH
                                    MIDDLE REACH
                                                    POINT
                                                  LOOKOUT


                                                   CHESAPEAKE
                                                       BAY
        Figure  1.  Potomac Estuary.
                   404

-------
Winters In the Potomac River Basin are moderately cold and the
summers warm, indicated by the mean monthly temperatures also
in Table 1.  Daytime temperatures of more than 35 C. are not
unusual in summer.  The frost-free season averages about 150 days.

Description of Potomac Estuary
For discussion and investigative purposes, the tidal portion of
the Potomac River was divided into three reaches shown in Figure 1
and described below:
                                                           Volume
                                                           3     7
     Reach           Description       River Kilometer   (m  x 10 )
     Upper      From Chain Bridge to    183 to 135          26.4
                  Indian Head
     Middle     From Indian Head to     135 to 75.0        102.5
                  Rt. 301 Bridge
     Lower      From Rt. 301 Bridge to  75.0 to 00.0       496.5
                  Chesapeake Bay

The upper reach, although tidal, contains fresh water.  The middle
reach normally is the transition zone from fresh to brackish water.
In the lower reach, chloride concentrations near the Chesapeake Bay
range from about 9,000 to 15,000 mg/1.

The tidal portion, about 60 meters in width at its head and at
Washington, broadens to nearly 10 km at its mouth.  A shipping
channel with a minimum depth of 7.5 meters is maintained upstream
to Washington,  Except for this channel and a few short reaches
where depths reach up to 30 meters, the tidal portion is relatively
shallow, averaging about 5.5 meters in depth.

The mean tidal range is about 0.9 meter in the upper portion near
Washington and about 0.5 meter near Chesapeake Bay.  The tidal lag
time between Washington and Chesapeake Bay is about 6,5 hours.  The
                                 405

-------
latitude and longitude of the centroid of  the Potomac  Estuary  are
38° 22' 150" and 77° 00'  300", respectively.   The  altitude  is  at
the level of the Atlantic Ocean.

                             TABLE 1
           MEAN MONTHLY TEMPERATURE AND PRECIPITATION
                               FOR
              WASHINGTON, D.  C.,  NATIONAL  AIRPORT
                           1933 - 1972
Month
January
February
March
April
May
June
July
August
September
October
November
December
Monthly Temperature (°C)
2.1
3.1
7.4
13.4
18.8
23.4
25.7
24.8
21.2
15.2
8.9
3.3
Monthly Precipitation (cm)
6.55
6.83
8.36
7.34
9.88
9.22
10.52
12.12
7.80
7.24
7.90
7.72
           WATER RESOURCE USES OF THE POTOMAC ESTUARY

Municipal Water Supply Use
The municipal water supply of the Washington metropolitan area
comes from five major sources, primarily the Potomac River above
Washington, D. C.  During 1969-1970, the five sources provided
        /-  n
1.4 x 10 • m /day.  Currently, no municipal water is drawn from
the freshwater portion of the Potomac Estuary; however,  an emergency
estuary intake was considered during the drought in the  summer of 1969.
                                 406

-------
Industrial Use
In the Washington metropolitan area, an insignificant amount of
water is used for manufacturing, primarily as cooling water in
stream electric plants.

Currently six major consumers in the Potomac River tidal system
             r  «3
use 10.4 x 10  m /day of cooling water.  A seventh user has
been proposed.

Recreation and Boating
Aside from enhancing the suburban environment, the water and land
resources of the Potomac Estuary and its tributaries improve the
aesthetics of the capital.  From Washington with its many tourists
to the remote park at Point Lookout near Chesapeake Bay, the
Potomac's resources are widely used.  These include freshwater and
tidal sport fishing, boating, hunting, swimming, camping, and picnicking.

Commercial Fisheries
The Potomac Estuary supports a substantial commercial fishery.
Approximately 160 fish species live in the Potomac Estuary ecosystem.
The most significant economically are the anadromous and the semi-
anadromous species such as striped bass, shad, white and yellow
perch, winter flounder, and herring.

Another group of commercially important fish species spawn and winter
outside of Chesapeake Bay in the Atlantic Ocean, using the Potomac
for a nursery area and feeding ground.  This group includes the
menhaden, croaker, silver perch, sea trout, and drum.

The lower reaches of the Potomac Estuary are considered prime shellfish
waters.  There oysters and soft clams are indigenous, occurring in
the same general areas.  Only in recent years, however, have  they been
harvested commercially, and the demand far exceeds the resource.
                                 407

-------
The lower Potomac affords a favorable habitat for blue crabs.   As
juveniles, the young crabs feed and grow in the Estuary before
completing their life cycle at the mouth of Chesapeake Bay.

                 WASTEWATER LOADINGS AND TRENDS
                           3
Approximately 1.4 million m" /day of municipal wastewater are dis-
charged into the upper reach of the Potomac River tidal system.
Currently, 18 waste treatment facilities serve approximately 2.8
million people in the Washington metropolitan area.
That current discharge is a nine-fold increase over the 0.16 million
m /day in 1913.  Similarly, total nitrogen and phosphorus loads
have increased about 10-fold and 22-fold, respectively (see Table 2),
                             TABLE 2
                    WASTEWATER LOADING TRENDS
                         (AFTER TREATMENT)
Year
1913
1932
1944
1954
1960
1970
Waste Flow
(m /day)
160,000
283,000
632,000
738,000
840,000
1,400,000
5-day BOD
(kg/day)
26,300
46,700
63,900
90,600
49,800
63,900
Total Nitro-
gen (kg/day)
2,900
5,200
10,400
14,400
16,800
27,200
                                                         Total Phos-
                                                        phorus (kg/day)
                                                              500
                                                            1,000
                                                            2,000
                                                            2,500
                                                            4,500
                                                           10,900
                    MORPHOMETRY AND HYDROLOGY

Morphometry
The basic morphometric data for the three reaches of the Potomac
Estuarv are tabulated:
                                408

-------
                                                Middle
                Lower
Length (km)
Avg. depth (m)
Avg. width (m)
               9     f\
Surface area  (m  x 10 )
Volume (m3 x 10?)
48
4.8
1100
57.4
26.4
60
5.1
3625
211.6
102.5
75
7.2
9740
695.2
496.5
Because of tidal action and low salinity, the upper reach is unstratified,
Stratification begins in the middle reach during summer conditions.  In
the lower reach, stratification occurs mostly during summer conditions.

Hydrology
The upr>er Potomac River Basin is the major source of freshwater inflow
into the Estuary.  From 1930-1968, the average flow at Great Falls
         3
was 305 m /sec before diversions for municipal water supply.

The mean monthly flows of the Potomac at Great Falls are tabulated
below for the reference period of 1931-1960.
           Mean Monthly Flow
               (nr/sec)
January
February
March
April
May
June
215
245
395
360
245
170
Mean Monthly Flow
    (m /sec)
                                     July
                                     August
                                     September
                                     October
                                     November
                                     December
       100
        75
        55
        55
        85
       110
Each year the Potomac River delivers about 2,300 million kilograms
of sand, silt, clay, and organic debris to the tidal system.  Most
of this usually occurs during February or March with maximum monthly
loads ranging from 50 to 90 percent of the total annual load.
                                 409

-------
Tides dominate the currents in the Estuary.   Typical maximum tidal
velocities for the three reaches are:

                  Reach                  Velocity (cm/sec)
                  Upper                         25
                  Middle                        28
                  Lower                         18

The hydraulic detention time for any given reach of the tidal system
depends on the rate of fresh water inflow.  The water renewal time for
the three reaches are given for the 5, 50, and 95% flow conditions:

 Flow      Percent of time          Hydraulic Detention Time (years)
(m /sec)    flow exceeded        Upper     Middle     Lower    Total
    40           95%             0.21       0.81       3.95     4.07
   185           50%             0.045      0.175      0.854    1.07
  1150            5%             0.0073     0.028      0.137    0.17

The above tabulation indicates that the upper reach has relatively
short detention times, while the lower reach has times similar to lakes,

                  LIMNOLOGICAL CHARACTERIZATION

Physical
Even though it is 189 kilometers long, the Potomac Estuary maintains
a rather homogeneous temperature.  While some stratification occurs
in the lower reach, tidal action appears to keep the system fairly
well mixed.

The mean monthly water temperatures in the upper Estuary recorded
for 22 years are:
                                 410

-------
          Month            °C            Month
January
February
March
April
May
June
2.5
3.3
7.8
14.0
20.4
25.9
July
August
September
October
November
December
28.1
27.8
24.7
18.4
11.5
4.8
The light penetration measured by the Secchi disk varies considerably
in the Potomac Estuary:

          Reach                   Ranges of Secchi Disk (meters)
          Upper                           0.4 to 0.8
          Middle                          0.5 to 1.3
          Lower                           1.0 to 2,3

The turbid upper reach has a rather low transparency due to particulate
natter originating in the upper river basin.  Suspended solids in
wastewater discharges also hinder light penetration.  During the summer
months, ttronounced algal growths in the lower part of the upper reach
sometimes limit Secchi disk depths to less than 0.15 meter.

The conductivity in the Potomac Estuary is related to the salinity
concentration.  The average ranges of conductivity and salinity for the
three reaches of the Estuary are:

                        Conductivity              Salinity
          Reach         ymhos at 25°C               0/00
          Upper         200 to 500             0.06 to  0.16
          Middle        600 to 17000           0.22 to  9.00
          Lower         17000 to 26000         9.00 to 15.00
                                411

-------
In the lower reach, significant stratification is due to a two-
layer flow of water --- that is,  an upper layer with a net seaward
movement and a lower layer with a net upstream movement.  The sea-
ward flow of fresh water results in less salinity in the lower
layer than in the upper layer of water.

Chemical
The Potomac River tidal system appears well buffered chemically.
Average ranges for pH and alkalinity are:
                                   pH                  Total Alka-
           Reach                (Units)               linity (mg/1)
           Upper               7.0 to 8.0               70 to 110
           Middle              7.5 to 8.2               60 to  85
           Lower               7.5 to 8.0               65 to  85

The well buffered inflows from the upper Potomac River Basin and
wastewater discharges maintain the Estuary in narrow ranges of pH
and alkalinity.  Tidal action keeps the system fairly well mixed.

Dissolved oxygen concentrations in the upper Potomac Estuary have been
routinely monitored since 1935.  In the Upper Estuary near the waste-
water outfalls, those concentrations have followed a continuous
downward trend since 1938, slightly enhanced in 1960.  Measurements
for the point of least concentration in the Upper Estuary illustrate
this downward trend:
                        Min. Consecutive           Min. Single Value
                         28 Day Average              During Period
                                                        (mg/1)
           1940                4.0                        3.0
           1948                3.5                        2.5
           1Q50                3.0                        2.3
           1955                2.5                        1.0
           1960                3.5                        2.5
           1965                3.0                        2.0
           1970                2.5                        2.0
                                412

-------
These low concentrations occurred mainly during the warm temperature
months in a zone extending about 10 kilometers from the wastewater
outfalls.

In the middle reach of the Estuary, dissolved oxygen decreased
significantly only during periods of massive algal blooms.  Tidal
action kept this region well mixed.

In the lower Estuary, low dissolved oxygen levels are common in
the summer months.  Concentrations less than 2.0 mg/1 occur in the
deeper reaches because high biological turnover with thermal and
salinity stratification restricts reaeration.

To date, trace elements in the water of the Potomac Estuary have not
been comprehensively analyzed.  A recent study by Jaworski, et al. (1971)
on heavy metals in the Estuary sediments has caused concern about the
accumulation of metals and resulting water quality problems.  The
study included analyses for lead, cobalt, chromium, cadmium, copper,
nickel, zinc, silver, barium, aluminum, iron, and lithium.

The concentration of nutrients along the Estuary varies as a function
of wastewater loading, temperature, freshwater inflow from the upper
basin, biological activity, and salinity.  Jaworski, et al. (1971, 1972)
have reported the annual distribution of the various nutrient con-
centrations.  Table 3 summarizes the summer levels for six key stations
along the Estuary.

In the vicinity of the Woodrow Wilson Bridge, the increase in total
and inorganic phosphorus, N0~ 4- NCL, ammonia, and total Kjeldahl
                            £3             .j
nitrogen can be attributed to the 1.40 million m /day of wastewater
discharged from the Washington metropolitan area.  Between Woodrow Wilson
Bridge and Indian Head, ammonia nitrogen rapidly disappears as nitrifying
                                 413

-------






















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bacteria oxidize NH  to NO  + NO .   NO  + NO. nitrogen drops
sharply between Indian Head and Maryland Point, taken up by the
pronounced algal growths in this area.

Biological
The previously described differences in salinity, as well as
nutrient enrichment by wastewater discharges, markedly affect
the ecology of the Estuary.  Under  summer and fall conditions,
large populations of blue-green algae, mainly Anacystis sp.,
prevail in the freshwater portion of the Estuary.  Large standing
crops of this alga occur, especially during periods of low flow,
forming green mats of cells.

In the saline portion of the Potomac Estuary, the algal popu-
lations are not as dense as in the  freshwater portion.  At times
large populations of marine phytoplankton occur, primarily
Gymnodinium sp. and Arophidinium ap_., producing massive growths
known as "red tides."

Increased nutrient loadings from wastewater since 1913 have
impressively affected the dominant  plant forms in the upper Estuary,
as documented by Jaworski et al. (1972) and shown in Figure 2.  Of
several nutrients and other growth  factors implicated as stimulating
this, nitrogen and phosphorus probably are the most manageable.

Plant succession in the upper Potomac Estuary can be inferred from
several studies.  Gumming (1916) surveyed the Estuary in 1913-1914
and noted the absence of plant life near thenajor wastewater outfalls.
He observed normal amounts of rooted aquatic plants on the flats or
shoal areas below the urban area, but no nuisance levels of rooted
aquatic plants or phytoplankton.
                                415

-------
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                                      416

-------
In the 1920's, water chestnut (Trapa natans)  infested the waters
of Chesapeake Bay and the Potomac Estuary.   This weed was controlled
by mechanical removal.

In September and October, 1952,  Bartsch (1954) surveyed the reaches
near the metropolitan area and found that vegetation was virtually
nonexistent in the area.  He reported no dense phytoplankton blooms
although the study did  not include the downstream areas where the
blooms subsequently occurred.

In 1958, a rooted aquatic plant, water milfoil (Myriophy-llum
spicatum), developed in the Potomac Estuary and created nuisance
conditions.  These increased to  major proportions by 1963, especially
in the embayments downstream from Indian Head (Elser, 1965).  These
dense strands of rooted aquatic  plants disappeared rapidly in 1965
and 1966, presumably due to a natural virus (Bailey, et al., 1968).

In August and September, 1959, Scotts and Longwell (1962) surveyed
the upper Estuary.  They observed high levels of the nuisance blue-
green alga, Anacystis sp., in the Potomac Estuary near Washington.
Subsequent and continuing observations have confirmed persistent
summer blooms of this alga in nuisance concentrations greater than
50 ug/1, occurring from the metropolitan area downstream at least
as far as Maryland Point.  Chlorophyll a_ determinations in the upper,
middle, and lower reaches of the Potomac Estuary are presented for
six key stations:
                                417

-------
       Station and Kilometers               Average Yearly
          from Chain Bridge            Range of chlorophyll (ug/1)
        Chain Bridge
        (0.0)                                   20 - 50

        W. Wilson Bridge
        (19.5)                                  30 - 60

        Indian Head
        (49.3')                                  30 - 150

        Maryland Point
        (84.3)                                  30 - 100

        301 Bridge
        (104.7)                                 10 - 30

        Point Lookout
        (185.0)                                 10 - 20
Diatom blooms have been observed in the late winter and spring.  The

occurrence and persistence of these blooms appear greatly influenced

by the spring runoff in the Potomac River Basin.


Nutrient Budgets

Runoff from the upper basin greatly influences the nutrient budgets

of the Estuary reaches.  Table 4 shows that the loading for carbon,

nitrogen and phosphorus is a function of the discharge flow from the

upper basin.  Considering only upper basin runoff and wastewater

discharges to the Estuary leads to the conclusion that the nutrients

to be controlled by wastewater treatment are (1) phosphorus, nitrogen,

and (3) carbon.


While the percentages of controllable ohosphorus and nitrogen decrease

at higher flows, these conditions usually occur during the months of

February, March, and April when temperatures and algal crops are lowest.

Since nuisance algal conditions occur primarily in the upper, freshwater

portion of the Estuary, the higher flow effects are considerably less
                               418

-------
                                      TABLE 4

                         SUMMARY OF MAJOR NUTRIENT SOURCES

                         Upper Reach of the Potomac Estuary

                                Low-flow Conditions
(95 % of time exceeded)
(Potomac River
Upper
Basin
Runoff*
(kg/day)
Carbon 77,100
Nitrogen 3,000
Phosphorus 450
Discharge at
Percent
of
Total
52
10
4
Washington, D. C.
Estuarine
Wastewater
Discharges
(kg/day)
72,600
27,200
10,900
3
= 40 meters
Percent
of
Total
48
90
96
/sec)
Total
(kg/day)
148,700
30,200
11,350
Median-flow Conditions

(Potomac River
Carbon 159,000
Nitrogen 18,100
Phosphorus 2,400
(50 %
Discharge at
68
40
18
of time exceeded)
Washington, D. C.
72,600
27,200
10,900

= 185 meters
32
60
82

/sec)
231,600
45,300
13,300
High-flow Conditions
(5 % of time exceeded)
(Potomac River
Carbon 6«0,00n
Nitrogen 185,000
Phosphorus 10,000
Discharge at
90
87
47
Washington, D. C.
72,600
27,200
10,900
3
= 1150 meters /sec)
10
13
53
752,600
212,200
20,900
*IIpper basin runoff includes both land runoff and wastewater discharges in upper
 basin.  The contribution of ground water and direct precipitation were estimated
 to be insignificant.
                                         419

-------
during July, August, and September when the blooms are most
prolific.

Current nutrient loading rates for the upper Estuary,  the upper
and middle Estuary combined, and the upper, middle and lower
Estuary combined are:
                                          2
            Nutrient Loadings (grams/meter  surface area/year)  at median flows
Nutrient        Upper       Upper & Middle       Upper, Middle, & Lower
Phosphorus       89.6            17.4                      5.0
Nitrogen        288.0            55.6                     16.9

Using the revised Vollenweider (in press) loading approach for  lakes,
Figure 3 shows the current rate for the three groupings of the  Estuary.
Figure 3 also shows the loading rate resulting from a protected degree
of phosphorus control and for the year 1913 as developed in the study
by Jaworski, et al. (1971).

Figure 3 demonstrates that providing a high degree of phosphorus
removal will cause the loading levels for 1he three combined segments
to approach the conditions of 1913.  Moreover, another ready con-
clusion is that the permissible and excessive loadings to the Estuary
would be considerably larger than for lakes.  Nevertheless, the
general overall relationship appears to hold true; that is, the
critical phosphorus loading is a function of mean depth/mean hydraulic
residence time.

When comparing the chlorophyll data of the Estuary to those of  the
OECD lakes, the Estuary appears less affected bv high concentrations
of chlorophyll.  In part this may be due to the greater mixing  of
the Estuary, compared to lakes.
                                420

-------
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        - "EUTROPHIC"
 
-------
                           DISCUSSION

The eutrophication problems in the Potomac Estuary are more pro-
nounced than those of other North Atlantic Coast estuaries.  While
the James and Delaware Estuaries are experiencing some eutrophication
problems, the more severe conditions in the Potomac can be classified
as hyper-eutrophic.

Analysis of the Potomac Estuary is complicated by two variables:
(1) salinity, and (2) light-limiting conditions.  Frequently high
sediment loads from the upper drainage basin and suspended matter
in wastewater discharges make the upper portion turbid.  This
light-limiting condition restricts algal growth in the upper portion
of the upper reach.   In the middle and lower reaches, light penetration
increases; however,  salinity also increases, resulting in a transition
from fresh-water to marine-water organisms.

Determining appropriate alternatives for water quality management,
including the eutrophication problem, of the Potomac Estuary requires
the ability to predict the effect of removing essential nutrients.
Numerous investigations, most dealing with lake eutrophication, have
attempted various approaches to relate trophic state and nutrient input.

An approach to defining a relationship between the ecology of the
Estuary and nutrient input can be delineated from the historical
data in Figure 2 and Tables 2 and 4.  The Estuary responded dramatically
to the large increase of nutrients mainly from the wastewater dis-
charges in the Washington, D. C. area.  The nutrient increase initially
resulted in rooted aquatic weeds with nuisance blue-green algal growths
overtaking the weeds when nutrients increased more.  Figure 2 shows
that phosphorus and nitrogen loadings should be about equal to the
1913-1920 conditions	about 600 kg/day of phosphorus and 3000 kg/day
of nitrogen from wastewater discharges	that resulted in no major
plant nuisances.
                               422

-------
Mathematica1 modeling has been another approach to relate trophic
state to nutrient input.  Studies summarized by Jaworski (1975) have
shown that the upper and middle reach of the Estuary become nitrogen
limited in the summer months.  Recent model studies by Clark (personal
communication) project that instituting a high degree of phosphorus
removal at the wastewater treatment facilities in the Washington, D. C.
area will make the Estuary either phosphorus or nitrogen limited.  The
degree to which either nutrient becomes limiting depends on factors
such as runoff and distance along the Estuary.  Jaworski et al. (1970)
used mathematical models with a 25 yg/1 chlorophyll target to estimate
wastewater nutrient loadings of 1000 kg/day of phosphorus and 3100
kg/day of nitrogen into upper zones of the Estuary.

A third appraoch, the loading concept developed by Vollenweider,
relates nutrient loading to mean depth/mean hydraulic residence time.
This has been developed mainly for phosphorus and lakes.  As previously
indicated, this method appears applicable to theEstuary but with higher
                                                    2
excessive and permissible loadings.  Using an 18 g/m /yr loading rate from
Figure 3, the loading for the Upper Estuary would be about 500 kg/day
from wastewater effluents after subtracting the non-point source
contribution.

The three approaches yield about the same values for phosphorus and
nitrogen loadings.  However, the Vollenweider loading concept needs
further verification with other estuaries before definitive relationships
can be formulated.
                                423

-------
                             SUMMARY

High oxygen-consuming and nutrient loadings,  mainly from domestic
wastewater discharges, have degraded the water quality of the
Potomac Estuary.  This high nutrient input has resulted in severe
eutrophication problems in the Estuary.

In this report the concept of critical phosphorus loading as a
function of mean depth/mean hydraulic residence time is applied
to the Potomac Estuary.  When compared to lakes, the Potomac Estuary
apparently has a much higher capacity for assimilating nutrients.
Furthermore, the Estuary apparently can tolerate high trophic states
because it is & well-mixed system.

The critical phosphorus loadings compare favorably to estimates
derived from historical data and mathematical modeling efforts.
However, more research is needed to determine the validity of using
loading concepts on estuaries.
                               424

-------
                           REFERENCES


Bagley, S., H. Rabin, and C. H.  Southwick.   1968.   "Recent
     Decline in the Distribution and Abundance of  Eurasian
     Water Milfoil in Chesapeake Bay."  Chesapeake Science,
     Vol. 9, No.  3.

Bartsch, A. F.  1954.  "Bottom and Plankton Conditions in
     the Potomac  River in the Washington Metropolitan Area."
     Appendix A,  A Report on Water Pollution in the Washington,
     D. C. Area.   Interstate Commission on  the Potomac River
     Basin.  Washington, D. C.

Clark, Leo.  Personal Communication.  Annapolis Field Station,
     Environmental Protection Agency, Annapolis, Maryland.

Gumming, H. S.  1916.  "Investigation of the Pollution and
     Sanitary Conditions of the  Potomac Watershed,"  Appendix
     to Hygiene Laboratory Bulletin 104. U.S. Public Health
     Service, Washington, D. C.

Elser, H. J.  1965.  "Status of  Aquatic Weed Problems in
     Tidewater Maryland, Spring  1965."  Maryland Denartment
     of Chesapeake Bay Affairs,  Annapolis.   8 pt>,  mimeo.

Jaworski, N. A.  1975.  "Use of  Systems Analysis in Water
     Quality Management of the Potomac Estuary."  Presented
     at seminar on System Analysis in Water Quality Management,
     Budapest, Hungary, Feb. 2-8.

Jaworski, N. A.,  L. J. Clark, and K. D. Feigner.   1971.  "A
     Water Resources-Water Supply Study of  the Potomac Estuary."
     Technical Report 35.  Chesapeake Technical Support Lab,
     Middle Atlantic Region, U.S. Environmental Protection Agency,
     Annapolis, Maryland.

Jaworski, N. A.,  D. W. Lear, and 0. Villa.   1972.   "Nutrient
     Management in the Potomac Estuary."  In:  Special Symposia,
     Vol. 1.  American Society of Limnology and Oceanography, Inc.,
     Milwaukee, Wisconsin.

Scotts, V. D. and J. R. Longwell.  1962.  "Potomac River Biological
     Investigation 1959."  Suoplement to Technical Appendix,
     Part VII of the Report on the Potomac  River Basin Studies.
     U.S. Department of Health,  Education,  and Welfare, Washington,  D.  C,

Vollenweider, Richard A.  (In press) "Input-Output Models."
     Schweiz Z. Hydrol.
                               425

-------
                         THE JOHN H.  KERR RESERVOIR -

                          VIRGINIA -  NORTH CAROLINA


                    Charles M.  Weiss  and Julie H.  Moore
            Department of Environmental Sciences and Engineering
                         School of Public Health
               University of North Carolina at Chapel Hill
                                INTRODUCTION
     The 2,785 foot long concrete dam that impounds John H. Kerr Reservoir is
located in Mecklenburg County, Virginia, on the Roanoke River, about 178.7
river miles above the mouth in the Albermarle Sound, 20.3 miles downstream from
Clarksville, Virginia; 18 miles upstream from the Virginia-North Carolina State
Line and 80 air miles from Richmond, Virginia.  Formed by closure of the dam
in 1952, the impoundment is a multipurpose project and was built for reduction
of flood damage in Lower Roanoke River, for generation of hydroelectric power
and for low water control for pollution abatement and conservation of fish
and wildlife.
                           GEOGRAPHIC DESCRIPTION


John H. Kerr Reservoir

     Latitude - 36° 35' 56";  Longitude - 78° 18' 06"

     Altitude - 300 feet MSL (maximum power tool)

     Catchment area - Total of sub-basins and lake 7,800 sq. miles

General Climatic Data

     The Climate in the Roanoke River Basin is temperate characterized by warm
summers and rigorous but generally not severe winters.  Light snow and subzero
temperatures occur annually in the western portion of the basin and occasion-
ally over the entire basin.  The average annual temperature for the basin is
about 14.4°C (58°F) and average monthly temperatures vary between 3.3°C  (38°F)
and 25°C (77°F), (See Table 1 on following page for detailed monthly temperatures)

     The average annual precipitation over the entire basin is about 43  inches
with annual extremes of 27 and 56 inches and is well distributed throughout the
year.  Precipitation varies from 50 inches near the mouth of the Roanoke River,

                                     426

-------
decreases with distance inland to 42 inches at about the center of the basin,

and then increases with elevation to approximately 54 inches at the headwaters

of the Dan River.  In the vicinity of the John H. Kerr Reservoir the average

annual precipitation is about 43 inches.  In the area at the headwaters of the

Roanoke River which lies between two mountain ranges (Allegheny and Blue Ridge

Mountains), the average annual precipitation is 38 inches.  The average annual

snowfall is about 13 inches and does not accumulate sufficiently to have a

noticeable effect on flood flows.

     Prevailing winds over the basin blow from the west to northwest in the

mountains and westerly elsewhere.  The average annual wind velocity is 7 to 11

miles per hour.  Wind velocities reach and exceed 80 miles per hour during

various types of storms.  Most of the annual wind damage occurs during intense

thunderstorms.

     The evaporation rate in the basin averages 37 inches from April to September,

which is 80 to 85 percent of the annual evaporation rate based on records for the

years 1954 to 1958 at Philpott and Kerr Reservoirs.


                                    Table 1

                     Average Maximum, Average Minimum and
                       Normal Monthly Air Temperatures*
                               John H. Kerr Dam

                 Average Maximum        Average Minimum            Normal
Month
January
February
March
April
May
June
July
August
September
October
November
December
°C
9.6
11.3
15.7
21.2
26.3
30.1
31.6
30.7
27.7
22.2
16.8
9.5
°F
49.3
52.3
60.3
70.2
79.3
86.2
88.9
87.2
81.9
72.0
60.8
49.1
°C
-2.6
-1.8
1.9
6.8
12.4
17.1
19.3
18.6
14.9
7.7
1.8
-2.0
°F
27.3
28.7
35.5
44.3
54.3
62.7
66.7
65.4
58.9
45.8
35.2
28.3
°C
3.5
4.7
8.8
14.1
19.3
23.6
25.4
24.6
21.3
15.0
8.9
39.4
°F
38.3
40.5
47.9
57.3
66.8
74.5
77.8
76.3
70.3
59.0
48.1
39.1
Annual          21.0        69.8         7.8       46.1       14.4        58.0

^Reservoir Regulation Manual, Roanoke River Basin, North Carolina-Virginia.  U.S.
 Army Engineer District, Wilmington, Corps of Engineers, Wilmington, N.C. October
 1965.

-------
General Geological Characteristics
     In general the Piedmont Province,  in which Kerr Reservoir is located, is
a maturely dissected upland underlain by a vast complex of igneous, metamorphic
and sedimentary rocks which are exposed in broad, northeast trending belts.
Deformation and intrusion of igneous material have altered preexisting igneous
and sedimentary rocks into metamorphic rocks which include gneisses, schists
and quartzites.  The older rocks have been intensely folded, displaced by faults,
and intruded by igneous rocks, predominantly granites.  The complexity of the
structure and the obscuring soil mantle make interpretation difficult and the
age relationships of many of the older formations uncertain.  One large body
and three smaller outliers of Triassic sedimentary rocks occur within the
Piedmont portion of the Roanoke River Basin.  These rocks consist of younger,
unaltered sandstones and shales which were preserved from erosion in
down-faulted basins.  Diabase and gabbro dikes have been injected into the
Triassic rocks as well as into some of the older igneous and metamorphic rocks
of the Piedmont Province.  Minerals abundant enough to be of commercial value
include tungsten, granite, gneiss, stone, sand and grave.
     Actual sediment accumulation (due to erosion) measurements from a 9-year
survey period 1950-1959 showed about one ton of sediment per acre per year  (or
639 tons per square mile per year).  This rate of sedimentation if  extended to
the whole Roanoke River Basin in Virginia would give a total of about 4 million
tons of sediment per year.

Vegetation
     Over 60% of the drainage area is forested predominantly by Virginia,
loblolly, and shortleaf pine, and mixed-pine hardwood stands; small areas of
pure hardwoods are  scattered  throughout the basin.  Vegetation on the lake
margins and in the  lake is severely limited due to the fluctuating water  level
                                      428

-------
and wave action on the shoreline.






Other Basin Characteristics




     The population of Roanoke River Basin in 1970 was 772,000.  Land use was




predominately rural-agricultural,  approximately 60% wooded, 30% cropland and




pasture, less than 10% urban and industrial.  Water use of the impoundment




includes flood control, hydroelectric power, low water control for pollution




abatement and for conservation of  fish and wildlife, recreation (fishing,




swimming, boating, etc.).   The reservoir waters are also under development as




a regional water supply for several North Carolina towns.







Sewage and Effluent Discharges




     Communities upstream of Kerr  Reservoir contribute waste water effluents




to the rivers and streams that flow into the basin.  In nearly all instances




these are treated sewages.   However, in some instances plant breakdowns will




release untreated wastes to the inflowing streams.  A recent compilation of




industrial and domestic point source discharges in the drainage of the




Roanoke basin is summarized in Table 2.  Monitoring of the Dan, Banister and




Roanoke River and Nutbush Creek illustrates the nitrogen and phosphorus




concentrations and load (kg/d) currently entering the Kerr Reservoir, Tables 3




and 4.  The configuration of John  H. Kerr Reservoir characterized by two




major arms each with substantially different morphometric and hydraulic




dimensions (see map and Tables 5 and 6) requires that nutrient loading rates




and characteristic productivity responses be examined independently for each.




In turn, since each arm receives its major nutrient input at the head end, each




arm has been subdivided into five  linear compartments, the discharge from each




becoming the inflow to the next downstream segment.
                                       429

-------
                                   Table 2

                           John H.  Kerr Reservoir
              Point Source Discharges,  Industrial and  Municipal
                         In Reservoir Drainage Area*
County
Industrial
Domestic
Virginia
Montgomery
Roanoke
Bedford
Franklin
Patrick
Henry
Pittsylvania
Campbell
Charlotte
Halifax
Appomattox
Mecklenberg
Other minor discharges
North Carolina
Vance
Granville
Rockingham
No.
3
15
9
3
5
11
10
10
5
12
-
-
-

-
-
-
MGD
.410
2.757
.305
.023
.528
54.799
16.834
6.364
.385
4.492
-
-
-

-
-
-
BODq Ib/day
75
75
-
8
303
3,279
20,334
1,995
34
11,325
-
-
-

-
-
-
No.
5
6
18
4
5
6
11
12
11
18
1
15
92

1
1
4
MGD
.181
29.029
.968
.606
.091
2.939
10.173
.830
.187
1.770
.100
.837
1.088

1.500
3.800
5.450
BOD5 Ib/day
54
6,077
975
154
164
2,637
935
454
105
1,965
30
346
561

626
1,809
2,823
                 Total   83   86.897    37,428
                    199   48.799    19,715
*Data for Virginia assembled from tabulations prepared  by  Hayes,  Seay,
 Mattern and Mattern for the Roanoke River Basin Study  and provided  by  the
 Wilmington District, U.S.  Army Corps of Engineers.   North Carolina  data  from
 The Division of Environmental Management, Department of Economic  and Natural
 Resources.

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                                   Table  4

                           John H.  Kerr Reservoir
     River and Stream Flows and Nutrient Loads Based on Monthly Samples
Roanoke River*

   July 1972-March 1973
   April 1973-March 1974
   April 1974-March 1975

Banister River*

   July 1972-March 1973
   April 1973-March 1974
   April 1974-March 1975

Dan River*

   July 1972-March 1973
   April 1973-March 1974
   April 1974-March 1975

North Drainage - April 1974-March 1975

   Bluestone Creek
   Little Bluestone Creek
   Butcher Creek

South Drainage - April 1974-March 1975

   Hyco River
   Aarons Creek
   Grassy Creek
   Island Creek
   Little Island Creek

Nutbush Arm

   Flat Creek - April 1974-March 1975
   Nutbush Creek
      July 1972-March 1973
      April 1973-March 1974
      April 1974-March 1975

Kerr Dam*

   Sept. 1973-March 1974
   April 1974-March 1975
   April 1974-March 1975
                                      No.  of  Average
                                      Samples  c .f,s.
               Total-N Total-P
                Kg/d     Kg/d      N/P
8
11
12
8
11
12
8
11
12
12
12
12
12
12
12
12
12
12
8
11
12
6
12
3,488
3,707
2,725
562
546
615
2,769
2,934
2,803
47
19
25
309
48
64
33
21
14
10.9
8.3
6.4
7,425
9,219
4,380
5,495
3,248
659
833
880
3,977
6,306
5,770
41
24
31
422
68
75
32
25
14
266
282
150
11,509
11,032
608
524
574
51
64
73
765
1,174
970
4.1
6.4
4.3
49
3.4
5.7
2.9
2.2
1.3
81
87
61
553
1,033
7.2
10.5
5.6
12.9
13.0
12.1
5.2
5.4
5.9
10.0
3.8
7.2
8.6
20.0
13.2
11.0
11.4
10.8
3.3
3.2
2.5
20.8
10.6
365   8,859
*Gaged flows, others calculated from weighted drainage area.
                                     432

-------
433

-------
                                   Table 5

                           John H.  Kerr Reservoir
            Distance of Sampling Stations or Reference Buoys  From
                              John H.  Kerr Dam
Roanoke Arm
Dam
2
4
8
14
58-15*
20*
24*
Nutbush Arm
Buoy A
C (103)
E
H (108)
K (111)
L
N (114)
P (116)
218 (From Buoy P)
1308
118
119
Miles
0
1.5
4.5
8.5
13.2
19.5
20
24

2.7
4.7
5.4
7.9
10.7
11.5
12.6
13.4
0.6
14.0
14.6
15.0
Km
0
2.4
7.3
13.7
21.3
31.3
32.2
38.6

4.3
7.5
8.7
12.7
17.3
18.5
20.3
21.5
0.9
22.4
23.3
24.0
*Distance scaled from 1,250,000 USGS  quadrangle  "Greensboro, N. C."
 Other distances scaled from USGS 1/24,000  quadrangles,  "John H. Kerr Dam" and
 "Middleburg, N. C."
                                     434

-------
                 MORPHOMETRIC AND HYDROLOGIC CHARACTERISTICS

                                   Table 6

                           John H. Kerr Reservoir
                Morphemetrie and Hydrologic Characteristics
Reservoir Surface

  At maximum flood-control pool (elev.  320)
  At maximum power pool (elev.  300)
  At minimum power pool (elev.  268)
  Original river area (below elev. 320)
  River elevation at dam elev.  200

Length at elevation 320

  Roanoke River
  Dan River above junction
  Nutbush Arm above Buoy A
Length of Shoreline at elevation 300
Maximum width at elevation 300

Volume

  Flood storage elev. 320 to elev. 300
  Volume at elevation 300
  Power draw down (elev. 300 to elev. 268)

Mean Depth

  Roanoke Arm, Dam to Buoy 24
  Nutbush Arm, Buoy A to 1308 bridge
   Acres
   83,200
   48,900
   19,700
    4,280
   Miles
       56
       34
       14
      800
        2

  Acre-Ft.

1,278,000
1,472,300
1,029,100

  Feet	

       33.7
       29.7
Ratio of Epilimnion to Hypolimnion - Transition depth   50
   Hectares

     33.670
     19,789
      7,972
      1,732
  Kilometers

         90
         55
         22
      1,287
          3.2

 Meter3 X 103

  1,576,400
  1,816,067
  1,269,384

	Meters

         10.3
          9.1
                        15.2
  Acres - 48,900/11,000           hectares - 20,231/4,452
  Acre-Ft. - 1,472,300/186,800    meters3 X 103 - 1,816,067/230,416
Stratification

     Seasonal heating generally produces a thermal gradient of more than

2°C, in depths of 70-80 ft. (21.3-24.4 m) as early as mid-March.  The upper

15 feet (4.6 m) may still be well mixed at this time.  By mid-May the temperature

differential between the surface and the deeper portions of the reservoir has

increased to 5°C with the transition depth between 20 and 25 ft. (6.1-7.6 m).

In the upper arms of the reservoir the transition depth shallows to a depth of

10 to 15 ft. (3.0-4.6 m).  In spite of hydro-power withdrawals stratification

persists with a 10°C differential, top to bottom, evident in August and the

                                     435

-------
transition depth persisting between 40 to 50 ft.  (12.2-15.2 m).   Seasonal
cooling produces the fall overturn late in November and the reservoir is
generally well mixed by early December.  Water temperatures lower than 4°C are

seldom found during the short winter period of December through February.

Lake Sediments
     Bottom sediment samples from locations along the axes of the Roanoke and

Nutbush Arms of John H. Kerr Reservoir as well as in several of the lateral arms
that were also sampled for benthic organisms, were characterized according to
particle size dimension.  These defined the sand, silt and clay content.  In
addition the carbon content of these sediments was also determined by
dichromate oxidation, Tables 7 and 8.  As might be expected the sand content of
the bottom sediments was much higher at the upper end of the Roanoke Arm
changing to a higher proportion of clay in the deeper portion of the impoundment.

Along the Nutbush Arm the silt content was generally greater than sand, which

was primarily limited to sublittoral locations.  The carbon content of the

Nutbush Arm was also greater at its upper end where a substantial pollution
load enters.  Even at the farthest downstream station, 103, the carbon content
of the sediment was still slightly higher than the average carbon content of
the main impoundment.

Seasonal Variation of Precipitation

     The rainfall pattern of this area is characterized by regional
precipitation originating in air masses flowing from the Gulf of Mexico.  This
is generally true of the winter and spring rains which give way to localized
thunderstorms from May to September.  Except for the random intrusion of sub-

tropical hurricanes, the fall months, particularly October and November, are

the driest although midsummer droughts are quite common.  The monthly
                                       436

-------
                                  Table 7
                           John H.  Kerr  Reservoir
              Particle Size Characteristics  of  Bottom  Sediments
Particle Size Range, mm.

        Stations

Roanoke Arm

          24
          20
          14
 Sand
1-0.625
                                     Percent,  By Weight,  Total  Sample
 17.8
 21.7
  0.0
  0.0
  0.0
    Silt
0.0039-0.0625
    31.3
    26.9
     8.3
    24.0
    11.8
 Clay
0.0039
 51.2
 53.0
 91.7
 76.0
 88.2
Butcher Creek

         214
  0.0
    34.4
 65.6
Eastland Creek
         211
  0.0
    30.2
 69.8
Nutbush Arm

         119
         118
         118E
        1308
        1308E
         116
         114
         114E
         111
         111W
         108
         103
         103W
Flat Creek
         219
         219S
         218
         218 S
  0.0
  0.0
 62.2
 20.3
 35.0
  7.7
  6.0
 38.1
  0.0
 73.6
  0.0
  0.0
 62.2
 13.9
 34.9
   0
 37.2
84.5
74.6
21.5
13.2
40.3
35.6
27.0
41.9
24.4
17.8
22.0
16.0
25.7
    28.9
    34.7
    38.4
    40.3
                       15.5
                       25.4
                       17.3
                       65.9
                         ,6
                         .6
 24.7
 56.7
 67.0
 20.0
 75,
  8.
 78.0
 84.0
 12.1
 57.2
 30.5
 61.6
 22.5
Letter designated stations are sub-littoral locations, others center channel
locations.
                                   '  437

-------
                                  Table  8

                           John H. Kerr Reservoir
                   Percent Carbon Content Bottom Sediments
   Date Sampled  Aug. 1973

 Station

Roanoke Arm

    24
    20
    14
             Nov.
           Feb.  1974
                         Average
Butcher Creek

   214

Eastland Creek

   211

Nutbush Arm

   119
   118
   118E
  1308
  1308E
   116
   114
   114E
   111
   111W
   108
   103
   103W

Flat Creek

   219
   219S
   218
   218 S
2.03
1.71
1.57
0.51
2.31
0.60
2.10
1.66
1.63

2.13
                          2.48
                          2.03
                          1.78
                          2.22
                          2.23
2.23
1.89
4.03
3.33
0.94
2.46
-
-
2.30
0.79
-
0.48
-
-
0.52
3.97
3.38
1.04
2.35
1.15
2.67
2.31
0.60
2.27
0.20
-
-
0.30
3.83
3.38
0.71
2.23
1.14
2.90
2.56
0.71
2.27
0.65
2.30
2.20
0.67
1,20
0.46
1.97
0.59
                           1.75
                           1.88
                           2.17
                           2.32
                           2.13
2.13
2.00
1.90
0.73
2.40
0.65
                          2.12
                          1.94
                          1.98
                          2.27
                          2.10
2.12
1.82
3.95
3.35
0.33
1.90
0.95
3.00
2.60
0.70
2.30
0.90
2.50
2.51
0.53
3.95
3.36
0.76
2.24
1.08
2.85
2.36
0.70
2.28
0.56
2.40
2.36
0.51
1.58
0.57
2.20
0.61
Percentages carbon determined by dichromate oxidation.
For conversion to "organic matter" multiply by a factor of 1.33.
Letter designated stations are sub-littoral locations, others center channel
locations.                            ,00
                                      4 JO

-------
precipitation record for Henderson, N. C., at the head of the Nutbush Arm of

John H. Kerr Reservoir, is presented in Table 9.

Water Renewal Time

     The water renewal or retention time of an impoundment operated both for

hydropower and flood control needs to be considered over a range of discharges.

For both arms of John H. Kerr  Reservoir water retention has been calculated

over a range of discharges based on annual averages, Table 10.  The difference

in retention time of the two arms is generally by a factor of 30.

                         LIMNOLOGICAL CHARACTERISTICS
Physical and Chemical

     Year round collection of limnological data from John H. Kerr Reservoir

early established a lengthy stratification period, April-November inclusive,

and a limited period in which the body of water was in a mixed condition,

December-March inclusive.  Water temperatures in the reservoir during the

current period of observation never fell to 4°C and thus stratification in the

spring generally proceeded rapidly.  In the following data tables, the

presentations when feasible are organized into the two yearly periods of April-

November and December-March.  Samples collected after November 25, in some
instances, were considered as part of the winter period.  Data from vertical
profiles are averaged as epilimnetic or hypolimnetic with the transition depth
indicated for each station.  Physical characteristics are presented in Tables
11 and 12 and chemical characteristics in Tables 13, 14 and 15.

Biological-Phytoplankton

     As with the physical and chemical parameters the phytoplankton have been  grouped

into April-November and December-March data sets.  For this report the quanti-

tative phytoplankton presentation is limited to cell no. per milliliter.
                                      439

-------
                                   Table 9
                           John H. Kerr Reservoir
                Seasonal Variation of Monthly Precipitation*
                               Total Annual Rainfall - Inches
1972
49.07
51.53
52.25
50.30
Monthly
Precip. - inches
6.37
4.38
3.70
4.03
1.34
5.89
3.37
.99
10.03
7.76
1.26
1.19
4.02
6.22
2.97
1973 1974
38.30 49.24
45.41 43.62
45.61 43.43
49.91 47.96
Departure
From Average
3.22
1.11
.34
.31
-1.75
2.27
-.79
-4.57
5.37
4.16
-1.36
-1.94
.77
2.95
-.39
Long Term
Average
41.83
41.91
-
40.04















Virginia Stations

   Halifax

   Clarksville

   John H., Kerr Dam

North Carolina Station

   Henderson



Henderson

December 1973

January 1974

February

March

April

May

June

July

August

September

October

November

December

January 1975

February
*Data  from  National Climate Center, Asheville, N. C.
                                     440

-------
                         Table 10

                 John H. Kerr Reservoir
        Water Renewal Time (Retention Time)-Days
   Regulated Discharge - Hydropower and Flood Control
       Average                        Roanoke Arm
Flow Rates - c.f.s.          1.054,719 Acre-Ft.  (elev.  300)

        7,500                            71

        8,000                            67

        8,500                            63

        9,000                            59

        9,500                            56

       10,000                            53


                                      Nutbush Arm
                              363,400 Acre-Ft. (elev. 300)

           90                         2,036

           95                         1,929

          100                         1,832

          105                         1,745

          110                         1,666

          115                         1,593

          120                         1,527
                           441

-------






























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Associated parameters, productivity, both Ps and Pmax, chlorophyll ji and Secchi




depth, (Phytoplankton sample depth) are presented in Table 16.  Characterization




of the total phytoplankton community by class and percent of each class of the




total is presented in Table 17.







Algal Assay




     Algal assays for limiting nutrients in each of the two arms of John H. Kerr




Reservoir over the total period of observation from March 1972 through May 1974




show a characteristic "downstream" decrease in growth potential as indicated by




the quantity of biomass grown in the reseeded control.  This was evident in both




filtered and autoclaved samples.  Of particular interest is the clearly




indicated shift from a higher frequency of nitrogen limited assays, at the




head of each arm of the reservoir, changing to more frequent phosphorus-limited




assays at the downstream end, Table 18.  This would be related to the observed




decrease in concentration of PO^-P and Total-P at these same stations.







Biological-Zooplankton




     The total zooplankton populations of the sampling points along both arms




have been defined by vertical net tows in the euphotic zone.  Monthly totals




and the April-November averages are presented in Table 19.  A genera list is




presented in Table 20.







Bottom Fauna




     Dredge samples from the stations along the two major arms of the reservoir




as well as several side embayments were collected in four seasonal periods to




define the bottom fauna.  The density of five major groups as found in the four




collections is presented in Table 21.
                                      447

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                         Table  20
                 John H.  Kerr Reservoir
                  Genera  of Zooplankton
                  Net Tows rv 1973-1974
COPEPODS
     Argulus sp.
     Diaptomus spp.
     Misc. Calanoid Adults + copepodids
     Cyclopoid Adults + copepodids
     Harpacticoid Adults
     Nauplii
CLADOCERA
     Alona sp.
     Bosmina longirostris
     Ceriodaphnia sp.
     Daphnia sp.
     Diaphanosoma sp.
     Leptodora kindtii
     Pleuroxus sp.
     Unknown Cladocera, adults and immatures
ROTIFERA
                                        PROTOZOA
Ascomorpha sp.
Asplanchna sp.
Brachionus sp.
Collotheca sp.
Conochiloides sp.
Conochilus sp.
Epiphanes sp. (?)
Filinia sp.
Gastropus sp.
Hexarthra sp.
Kellicottia bostoniensis
Keratella sp.
Lecane sp.
Monostyla sp.
Ploesoma  sp.
Polyarthra sp
Proales sp.
Rotaria sp.
Synchaeta sp.
Testudinella sp. (?)
Trichocerca  sp.
Unknown Flosculariidae
Unknown Rotifera
                                                  Actinosphaerium sp.
                                                  Arcella sp.
                                                  Difflugia sp.
                                                  Epistylis sp.
                                                  Paramecium sp.
                                                  Stentor sp.
                                                  Vorticella sp.
                                             OTHERS
                                                  Chironomidae
                           452

-------




















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-------
Fish
     Although the John H. Kerr Reservoir is one of the more popular fishing
locations in the Virginia-North Carolina region, quantitative data on the
productivity of the fishery is somewhat limited or unavailable at this time.
The data of two limited creel censuses from North Carolina waters, primarily
Nutbush Arm are as follows:
1964-1965 Census; 385 contacts yielded a gross catch rate of 0.86 fish/hr. —
which 54% were "sunfishes" (other than crappy, bluegill and redbreast sunfish),
30% catfish, 10% crappy, 3% carp, 2% large mouth bass, 1% pickerel and 1% other
species.
1970-1971 Census; 413 contacts yielded a gross catch rate of 1.79 fish/hr. —
of which 68.6% were crappy, 15.4% bluegill, 11.3% catfish, 1.5% large mouth
bass, 1.3% "sunfishes," 0.6% pickerel, 0.5% carp, 0.4% rough fishes, 0.4%
striped bass.*

                               NUTRIENT BUDGETS
Nitrogen and Phosphorus
     The nutrient budget presented in Table 22 is described for the period
April 1974-March 1975.  Only data collected within this period has been used in
this budget.  Values estimated include land runoff,  non-gaged sources, and
the relatively weak concentrations for N and P in rainfall.  The Kerr Dam
discharge used in this budget, 8859 c.f.s. is based on 365 daily samples
whereas the average of the 12 samples taken monthly is 9219 c.f.s.  The
concentrations of N and P in these 12 samples were used to calculate the
discharge (kgs/yr.) using the flow of 8859 c.f.s.  The validity of this
computation appears to be justified by the budgets computed for Cl~ and SO^ .
*Creel census data provided by the N. C. Wildlife Resources Commission.
                                      455

-------
                                   Table  22

                           John H.  Kerr  Reservoir

                  Nutrient Budget - Nitrogen and Phosphorus
                           April 1974  -  March 1975
                                            Average        	kgs/yr	
Source of Flow                           Discharge c.f.s.    Total-H  Total-P

ROANOKE ARM

   Principal Rivers

      Roanoke                              2,725
      Banister                               615
      Dan                                  2,803     6,143 3,612,770 590,205

Three Streams - North Drainage                91               35,040   5,402
Five Streams - South Drainage                475              227,030  23,068

Point Sources Discharges, 7 Municipal
and Industrial to Kerr Reservoir or
to Flows Downstream of Sampling Points         2.7              85,733  23,411

                                 Total               6,712

             Discharge J. H. Kerr Dam                8,859

Average Discharge Nutbush Arm All Sources              115

Net Flow Roanoke Arm (8859-115)                      8,744

Net Flow Non-Gaged Streams and
   Other Flow - Roanoke Arm (8744-6712)              2,032    686,565  58,035
   (T-N..378 mg/1, T-P - .032 mg/1,
   averages of five non-polluted streams)

Rainfall, 43"/yr/30,866 acres                          153

Evaporation^                                          -153

N and P Contribution by rain2'3'1*
   N03;  .62 mg/1; Total-P, 0.1 mg/1
43"/yr/30,866 acres                                            18,556  13,644

                          Total Roanoke Arm                 4,665,694 713,765

NUTBUSH ARM

   Flat Creek                                 14                5,110     474
   Nutbush Creek                               6.4              54,750  22,265

Flow Non-Gaged Sources                        94.6             31,967   2,697
   (115-20.4)

Rainfall 43"/yr/12,452 acres)                                   7,488   5,506

                          Total Nutbush Arm                    99,315  30,942

                          Total J. H. Kerr Reservoir        4,765,009 744,707
                          Kerr Dam Discharge                4,026,680 377,045
                                % Retained                         16      50


 'Yonts  and  Giese,  1974
 2Gambell and  Fisher,  1966
 3T-P  determined  on rainfall  samples  collected at Chapel Hill,  N.C.  13 and 25
    April  1972.
 "*Uttormark and  Chapln,  1974.
                                    456

-------
Fe, Cl  and S04~

     Utilizing the same flow data used to compute the budget for nitrogen and

phosphorus, the pass through for Fe, total, dissolved and particulate and Cl

and S0^~ was'also calculated, Table 23.  The expected large reduction of total

and particulate Fe was confirmed and to a somewhat lesser degree the dissolved

Fe.  The close agreement of both Cl  and S0^~ for net pass through endorses the

validity of the flow values used.


                                  DISCUSSION

     The limnological characteristics of a reservoir are basically defined by

the velocity change as the inflowing rivers and streams encounter the standing

water of the impoundment.  In turn downstream flow through the impoundment and

average retention time becomes a function of the relative inflow volume and

rate of discharge.  This down reservoir movement is also generally over an

increasing mean depth since the deepest point and in many instances the

maximum surface area of an impoundment is at or adjacent to the dam.  The

dimensional parameters of mean depth (z), residence time (TW), flushing rate

(1/Tw), retention coefficient (R) and areal loading (qs) for each of the

segments of each arm of John H. Kerr Reservoir have been calculated and

arranged in Table 24.  With these dimensions the associated phosphorus

fraction concentrations and loading (Lp, g/m /yr) are also presented.  The

changing magnitude of all dimensions in downstream movement and the

considerable difference in flushing rate and loading between the two arms of

this reservoir provides an opportunity to test the validity of the Vollenweider

numbers against the observed trophic state of each compartment (Vollenweider

and Dillon, 1974).  The relationships of areal loading  (qs) versus phosphorus

loading is shown in Figure 1 and phosphorus loading and productivity as

determined by chlorophyll a^ production is examined in Figure 2.  The differences

in behavior of the two arms of John H. Kerr Reservoir is clearly seen with the
                                      457

-------
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flushing rate as a major controlling variable in establishing both the net
available phosphorus as well as its rate of utilization.  In a final analysis
the several independent variables that describe the conditions for algal growth
are compared to growth as determined by chlorophyll a. and productivity (Ps),
Table 25.  Again the consistent high correlations of the Nutbush Arm as
compared to the low or non-correlations of the Roanoke Arm indicate a major
dependency of the system on flushing rate to establish growth limiting conditions.
     A preliminary analysis of productivity at secondary levels, total
zooplankton numbers and associated algal cell density shows that in the
Roanoke Arm the correlation has a r value of -.340 whereas in the Nutbush  the
r value is .871.

                                    SUMMARY

     The John H. Kerr Reservoir, a hydro-power flood control impoundment of
48,900 acres, receives a substantial nutrient load of nitrogen and phosphorus
from upstream municipal and industrial waste water discharges.  Because of
the relative flow into the two major arms of the reservoir, that of the Roanoke
being about 80-90 times greater than the Nutbush the residence time of the  two
arms varies by a factor of 30, 60 days versus 1,800 days.  Nutrient budgets
for nitrogen and phosphorus indicate for the period April 1974 to March 1975
about 16% of the nitrogen was retained in the impoundment and 50% of the
phosphorus.  Budgeting for Cl  and S0^~, utilizing the same flow values,
accounted for essentially the entire load, -4% for Cl  and +5% for S0^~.
     Examination of P budget parameters and the response of the system of  each
arm subdivided into five segments verifies with high correlations the validity
of areal loading and Total-P as predictive dimensions when retention time  is
•high.  At high flushing rates the correlation values are lower.  Impoundments
with high phosphorus retention coefficients exhibit considerable capacity  to
                                      462

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                                Table  25

                         John H. Kerr  Reservoir
         Correlation Coefficients - Growth Controlling  Variables

                          April-November Data


                                  	Dependent Variables
                                    Chloropl
Independent
Variables

Loading Pg/m2/yr.

Total P - Total Profile

Total P - Epilitnnion

Total Soluble P - Epilimnion

Areal Loading

Flushing Rate

Secchi Depth



R - Roanoke Arm stations

N - Nutbush Arm stations
Chlorophyll
mg/m3
R
.836
.923
.608
.561
.817
.871
-.805
a
N
986
985
975
953
993
995
830
Primary Production
gC/m2/d
R
.757
.755
.419
-.060
.743
.602
-.077
N
.989
.991
.965
.951
.999
.995
.745
                                      463

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remove phosphorus from downstream systems.  Even with comparatively short

residence time, such as the Roanoke Arm, phosphorus removal by adsorption on

iron rich sediments may be of considerable magnitude.


                              ACKNOWLEDGEMENTS

     The collection of data for this report involved both staff and graduate
students of the Department of Environmental Sciences and Engineering.  The
following should be acknowledged for their specific contributions which in
several instances will be discussed in greater detail in the final report on
John H. Kerr Reservoir, currently in preparation:

     Field Collections:  Mark A. Mason, Tom M. Ronman, Robert P. Sniffen
     Benthos:  David Y. Conlin
     Phytoplankton:  Sheila L. Pfaender, Ronald T. Kneid

     The cooperation of the Corps of Engineers, Wilmington District, throughout
this study and in providing the basic morphometric information on John H. Kerr
Reservoir is gratefully acknowledged.

     A detailed critique of the hydraulic estimates by Dr. William J. Snodgrass,
McMaster University, Hamilton, Ontario, has provided an opportunity to further
refine the loading calculations, between the  several drafts of this report.
                                 REFERENCES


Gambell, A. W. and D. W. Fisher.   Chemical Composition of Rainfall Eastern
     North Carolina and Southeastern Virginia.   Geological Survey Water-
     Supply Paper 1535.  1966.

Uttormark,P. D. and J. D. Chapin.  Estimating Nutrient Loadings of Lakes from
     Non-Point Sources.  Water  Resources Center, University of Wisconsin,
     Madison.  Ecological Research Series, U.S. Environmental Protection Agency.
     EPA-660/3-74-020.  August  1974.

Vollenweider, R. A. and P. J. Dillon.  The Application of the Phosphorus
     Loading Concept to Eutrophication Research.  National Research Council
     Canada.  Associate Committee on Scientific Criteria for Environmental
     Quality.  NRCC No. 13690.   June 1974.

Yonts, W. L. and G. L. Giese.  The Effect of Heated Water on the Temperature
     and Evaporation of Hyco Lake, North Carolina, 1966-72.  U.S. Geological
     Survey, Water Resources Investigations 11-74.  May 1974.

Vollenweider, R. A.  EPA-OECD Spring Workshop,  North American Project.
     University of Minnesota, May 14-15, 1975.
                                     464

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             TROPHIC STATUS AND NUTRIENT LOADING FOR LAKE TAHOE

                             CALIFORNIA-NEVADA


                             Charles R. Goldman

                     Division of Environmental  Studies
                         University of California
                            Davis, California


                              I.  INTRODUCTION

     Lake Tahoe, located in the Sierra Nevada on the California-Nevada border,
is a large, deep, ultra-oligotrophic lake which is usually monomictic.  The
lake, formed in a graben fault, has steep sides, a flat bottom and very little
shallow water for its size (Fig.  1).  Over 60 tributaries flow into the lake
which is drained by one major outflow.

     Lake Tahoe is particularly renowned for the great transparency of its
water and the beauty of its deep blue color.  It is surrounded by high mountains
that are covered with snow during several months of the year.   These character-
istics make the lake basin an ideal place for year-round recreational  activities
which attract thousands each year.  During the last few decades, there has been
a dramatic increase in both the resident and tourist population at Tahoe re-
sulting in serious environmental  disturbance.  By 1962 sewage  discharge, even
after treatment, was shown to greatly stimulate phytoplankton  primary produc-
tivity in the nutrient poor Lake Tahoe water.  The export of treated effluent
from the basin was started shortly thereafter,  with completion of most of the
sewage diversion process by 1970.

     As the population continues to increase in the Tahoe basin with a concom-
itant rise in construction activities (road building, housing  developments),
serious damage to the watershed of the lake continues.  The exposure of mineral
soil to erosion and the resultant leaching of nutrients is a factor in the
cultural eutrophication of the lake.  Large plumes of sediments extending from
tributary streams into the lake and the appearance of luxuriant growths of
attached algae around the lake margin in the last ten years were the first
clearly visible signs of change in the lake (Goldman 1974).

     During the last 16 years Lake Tahoe has been the subject  of intensive lim-
nological research with emphasis on the lake's  primary productivity, nutrient
limiting factors and the process of eutrophication.  Since 1972 the research
program has expanded into a multidisciplinary research project (supported by
NSF-RANN Grant GI-22) with the principal objective being the identification
and measurement of the impacts (physical, chemical, biological, and social) of
commercial and recreational development of the  Lake Tahoe basin.  The Ward
Creek watershed has been chosen for intensive studies of nutrient flux and
sediment transport through the watershed and their impacts of lake water quality.
                                    465

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     Primary productivity has proven to be one of the most sensitive indicators
of eutrophication in Lake Tahoe  (Goldman 1974, Goldman and Amezaga in press).
Its level has increased alarmingly over the last 15 years of research.
                                  LAKE  TAHOE
                                                       INCLINE CREEK
                                                      SAND POINT
           TRUCKEE RIVER
                                                     SKUNK HARBOR
                                        UPPER TRUCKEE RIVER
Figure 1.  Bathymetric map of Lake Tahoe indicating the index station and
           other locations.  The contour interval  is 50 m.   The shaded area
           indicates the littoral  zone which extends to 100 m depth.   A few
           tributaries only are shown.  (After Goldman 1974)
                                      466

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                II.  GEOGRAPHIC DESCRIPTION OF WATER BODY

A.  LATITUDE AND LONGITUDE

Lake Tahoe is situated in the Sierra Nevada mountains at latitude 39°
06' and longitude 120° 02' (centroid of water area).

B.  ALTITUDE OF THE LAKE ABOVE SEA LEVEL

The natural level  of the outlet from the lake is 1897 meters and the
lake surface level is regulated for the purpose of water storage.  A
low dam located at the Truckee River outlet serves this purpose and
maintains the level between 1897 meters and 1899 meters.

C.  CATCHMENT AREA

The total catchment area, including the area of surface water, extends
over 1310 square kilometers.

D.  GENERAL CLIMATIC DATA

Lake Tahoe never freezes; only some harbors and marinas have periodic
ice coverage in the winter.  Its large volume of water stores enough
summer heat to prevent Lake Tahoe from freezing in the winter.

Average monthly air temperatures for two locations on the shore of the
lake are shown in Table 1.

Table K  Average Air Temperature Data in °C (McGauhey et a!. 1963)
January
February
March
April
May
June
July
August
September
October
November
December
Annual
At Tahoe City for
22 year period 1931-52
-3.2
-2.1
0.2
3.8
7.8
11.7
16.1
15.8
12.4
7.2
1.7
-1.2
5.8
At Glenbrook for
17 year period 1945-61
-0.6
0.2
2.2
5.6
9.2
14.1
18.8
18.8
15.2
9.4
4.4
0.8
7.2
                                    467

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The climate is influenced primarily by marine air masses moving inland
from the Pacific Ocean.  Continental influence occurs occasionally.

Predominant winds are from the west, southwest or northwest.   Within the
basin the lake forms an extensive plain which tempers the strong gusty
winds usually associated with montane areas.

Evaporation is estimated to average about 90 cm per year.

Evapotranspiration is about 60 cm per year.

E.  GENERAL GEOLOGICAL CHARACTERISTICS

The Lake Tahoe basin is bordered on its west side by the main crest of
the Sierra Nevada and by the Carson Range on the east.  The lake basin
is the southernmost of a series of tectonic depressions that form a NNW-
trending graben complex extending northward to the area of Mt. Lassen.

Granitic rocks of the Sierra batholith comprise the bedrock of the entire
southern half of the basin and along the eastern side as far north as
Incline Creek.  Extensive flows of principally andesitic volcanic rocks
of the Cenozoic age occur at the north end.   Little or no granitic rock
crops out in the basin west of Crystal Bay with the exception of State-
line Point.  Volcanic rocks are predominant on the west side as far
south as Blackwood Creek.

Approximately 70% of the runoff in the basin comes from granitic terrain,
25% from volcanic rocks and about 5% from metamorphic rocks (Court,
Goldman and Hyne 1972).  Sparse protective vegetation in many areas and
erodible soils result in appreciable erosion during heavy rain and spring
snowmelt.  Large sediment plumes extend into the lake during heavy runoff.

F.  VEGETATION

The lake shores are forested with coniferous trees.  Some meadows exist
in the tributary stream valleys with abundant stands of nitorgen fixing
alders in many places.  Rock exposures and steep slopes near the rim of
the basin may be almost devoid of vegetation.  Most of the forest is
second growth having been extensively lumbered in the late 1800's for
mining activity in Nevada.  Because of the dry summers and cold winters
revegetation is a slow process.  Some ski slopes have remained barren
for over a decade.

G.  POPULATION
The Lake Tahoe region is a recreational area.  Precise population esti-
mates are difficult to acquire and soon become obsolete.  Various com-
ponents of total population are present (listed below).  In view of the
dynamic nature of population in the Tahoe region, a peak seasonal popu-
lation number is commonly used as the population indicator.

The Tahoe Regional Planning Agency  (TRPA) has derived a population es-
timate from census data and economic activity analysis.  The total
estimate is 129,700 broken down into the following categories:
                                   468

-------
Permanent residents
Seasonal residents
Second-home residents
Motel/hotel visitors
Camper visitors
                                     26,100
                                     10,000
                                     32,000
                                     32,400
                                      6,700
Estimate day use visitors
          Total
                                    107,200
                                     22.500
                                    129,700
The total value of 129,700 represents the existing peak seasonal  popu-
lation.  (After preliminary draft of Lake Tahoe Study Section 114, PL
92i500, U.S. Environmental Protection Agency, October 1973).

H.  LAND USAGE

The Tahoe basin is used extensively for recreation (skiing, gaming,
tourism, watersports).  Land ownership is:
     1.  62% public land* (57% National Forest and 5% State Parks)
     2.  38% private land (67% of lake shoreline)
The majority of the developments are second-home subdivisions.   Legalized
gambling in Nevada has spawned several large casinos at the south and
north ends of the lake adjacent to the state line.

Considerable land is being acquired by governmental agencies.

I.  USE OF WATER

Tahoe is operated as a fluctuating reservoir to provide water for down-
stream users.  High water in spring causes shore line erosion and late
summer low water may leave some piers high and dry during unusually dry
years.  There are 34,000 acre feet (42 x lO^m3) allocated for use in the
basin (also see B).  Approximately 19,000 acre feet are actually being
used.  Fishing, boating, and some skin diving are  recreational  uses of
the lake.  With continued development a water shortage could  develop.

J.  SEWAGE AND EFFLUENT DISCHARGE

Sewage is collected by conventional sewage lines in most parts  of the
basin and is given tertiary treatment at the south end of the lake (South
Tahoe Public Utility District plant) before being  pumped out  of the basin
for recreation and irrigation.  Sewage at the north end of the lake has
been pumped into a cinder cone out of the Tahoe drainage after  primary
treatment.  This natural filter is now overloaded  and the rate  of in-
filtration into sewer lines may be great.  A few septic tanks persist
but the majority of sewage effluent is exported.  There is no significant
industrial effluent discharge, if any, in the basin.


        III.  MORPHOMETRIC AND HYDROLOGIC DESCRIPTION OF WATER  BODY

A.  SURFACE AREA OF WATER
                                 o
Lake Tahoe surface area is 499 km.  Its maximum length is 34.7 km, its
                              469

-------
maximum width is 19.2 km.   It has an average length of 32.9 km and an
average width of 15.4 km.   Lake Tahoe's shoreline measures about 113 km
(including bays and inlets).

B.  VOLUME OF WATER

Lake Tahoe has a volume of 156 km3 of water.  The top 1.86 meters of the
lake (elevation 1896.77 m to 1898.63 m), with a volume of about 0.9 km3
serves as a storage reservoir for the Truckee Carson Irrigation District
which operates it on behalf of the United States Government.

C.  MAXIMUM AND AVERAGE DEPTH

Lake Tahoe has a maximum depth of 501 meters and an average depth of
313 meters.

D.  EXCEPTIONAL DEPTHS AND SURFACE AREA RATIO OF DEEP TO SHALLOW WATERS

The lake basin has steep sides, a flat bottom and very little shallow
water for its size (Fig. 1).   Several large mounds (about 50 meters
high) occur on the floor of Laka Tahoe.

The shallow littoral zone of Lake Tahoe extends to about 100 meters
(Goldman and Amezaga 1974).  The surface area ratio of deep to shallow
water is 4.35.

E.  RATIO OF EPI- OVER HYPOLIMNION

The epilimnion of Lake Tahoe extends down to about 15 meters and its hypo-
limnion is located below 25 meters.  This gives Lake Tahoe a ratio of
epi- over hypolimnion of about 0.05 (7 km3/143 km3).

F.  DURATION OF STRATIFICATION

Stratification lasts from 6 to 7 months beginning about May and lasting
until November.  Complete mixing occurs in late winter if sufficiently
high winds and low temperatures persist.

G.  NATURE OF LAKE SEDIMENTS

The areal distribution of volcanic constituents of sand and gravel frac-
tions reflects volcanic sources in the north and northwest parts of the
basin.  Volcanic areas contribute montmorillonite to clay fractions
whereas vermiculite and chlcritic intergrades are characteristic
weathering products of granitic sources.

Two distinct types of sediment are present.  Pollen-rich diatomaceous
ooze (organic ooze) is characterized by the following:  (a) abundant
diatoms and pollen; (b) chloritic intergrades in the clay fraction; (c)
all samples from flat-lying, well stratified beds.  The other sediment
type (non-organic) is typified by:  (a) diatoms and pollen rare or ab-
sent; (b) vermiculite/mica/montmorillonite clay fraction; (c) not
present in "flat-lying" beds; (d) texturally more varied than organic
ooze.


                                    470

-------
Non-organic samples represent exposed depositional products of the Tioga
glaciation, reflecting relatively rapid erosion and slumping into deeper
parts of the basin.  The principal source of non-organic material was
the west side where volcanic rocks constitute about half of the area.
In contrast, organic ooze samples result from relatively passive post-
glacial fluvial erosion.  The relative abundance of biogenic components
in organic ooze reflects low depositional rates and the clay fraction,
rich in chloritic intergrades, points to the dominance of granitic source
rocks in the present basin-wide source (Court, Goldman and Hyne 1972).
H.  SEASONAL VARIATION OF MONTHLY PRECIPITATION
         Table 2.  Precipitation data in cm (McGauhey et al. 1963)
January
February
March
April
May
June
July
August
September
October
November
December
Annual
Precipitation increases dramatically with altitude in the basin.  For
example, 100 cm of precipitation fell during the 1973 water year and
187 cm during 1974 at 2195 m altitude in Ward Valley.
I.  INFLOW AND OUTFLOW OF WATER
The total average inflow of water:     The total average outflow of water
                                               from the lake:
from runoff water is about 0.382 km3   from evaporation is about 0.410 km3
from precipitation on lake 0.259 km3   from discharge            0.217 km3
                           	   from diversion            0.006 km3
Total inflow               0.641 km3   Total outflow             0.633 km3
Ground water movements in the basin are for the most part unknown.

                                   471
At Tahoe City for
43 year period 1910-52
15.39
13.82
9.91
5.28
2.82
1.52
0.66
0.38
1.17
4.24
8.41
13.54
77.14
At Glenbrook
17 year period
7.57
6.22
7.16
3.84
3.89
1.02
0.94
0.74
1.22
2.44
5.23
6.25
44.45
for
1945-61














-------
J.  WATER CURRENTS

Surface and mid-depth currents have been observed to be generally southerly.
Bottom currents were found to be generally southeasterly (McGauhey et al.
1963).

Periods of the surface seiches in Lake Tahoe have been determined to be
about 19 min.  (uninodal  seiche) or less (binodal  and transverse).  Water
level records  have indicated fluctuations with periods of about 12 and
24 hours and amplitudes  of a few millimeters.   These fluctuations are
possibly surface reflections of internal seiches  (McGauhey et al. 1963).

K.  WATER RENEWAL TIME

Retention time for Lake  Tahoe has been estimated  to be about 700 years.
                 IV.  LIMNOLOGICAL CHARACTERIZATION SUMMARY

*   Indicates that data on the parameter are (or have been) collected
    regularly and that the representative values given here have been
    selected from data covering a period of at least one year.

**  Indicates that data on the parameter are (or have been) collected
    occasionally.  However, the values given here are known to be quite
    representative.

All concentration values given below, for range limits, are actual point
measurements in the water column, unless otherwise indicated.  They are
not mean concentrations for the whole water column.  When mean concen-
trations over a period of time are given, values have been calculated
over both depth and time.

A.  PHYSICAL
*   1. Temperature range       4.57 - 20.35 °C (reversing thermometer)
       Representative profiles of temperature in the euphotic zone are
       shown in Fig.2

**  2. Conductivity range     86.9 - 104.3 pmho/cm 25°C  mean = 92 ymhos

*   3. Light penetrates to great depths in Lake Tahoe
       Secchi depth range     15.5 - 43.0 m  mean for 5 years = 28.3 m
       Some representative profiles of light transmission in Lake Tahoe
       are shown on Fig.  2
       Depth of 1% light
         transmission range     59 - 105 m
       Extinction coefficient
         range               0.044 - 0.078

**  4. Color measurements have been taken on Lake Tahoe waters by Smith,
       Tyler and Goldman  (1973), by using a spectroradiometer to measure
       absolute values of spectral irradiance and a transmissometer to
                                   472

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       measure beam transmittance.   They measured the spectral  composition
       of the radiant energy up- and down-welling from lake waters and
       evaluated the color attributed to lake waters in terms of the C.I.E.
       chromaticity coordinates,  They reported the tristimulus values
       and showed the plot of the tristimulus values on the C.I.E. chroma-
       ticity diagram which gives the numerical specification of the colors.
                                            -2    -1
*   5. Solar radiation range:  20-750 cal-cm  -day     Total  =
                                                       150,863 cal•cm"2-year"1
                                                       (average of 4 years)

B.  CHEMICAL

**  1. pH range                7.3 - 8.0

*   2. Dissolved oxygen range  6.85 - 11.57 mg/1
       There is essentially no oxygen depletion in Lake Tahoe.

*   3. Total phosphorus range:
       epilimnion (0-15 m)     0.7 - 20.4 yg/1         with mean = 2.8 yg/1
                                                       for growing season
       euphotic zone (0-105 m) N-D - 25.0 yg/1         (N-D = non detectable)
       whole lake (0-400 m)    N-D - 25,0 pg/1         with mean = 3 yg/1
       We have not been able to measure satisfactorily the fractions of
       phosphorus which are present in very small amounts.  The mean dis-
       solved phosphorus value is less than 5 yg/1.

    4. Total nitrogen
*      NOo-N range:
       epilimnion (0-15 m)     N-D - 25 yg/1           with mean = 4.3 yg/1
                                                       for growing season
       euphotic zone (0-105 m) N-D - 26 yg/1           with mean = 7 yg/1
                                                       (one year)
       whole lake (0-400 m)    N-D - 26 yg/1           with mean = 13 yg/1
                                                       (one year)
       Other forms of nitrogen have not been measured on a regular schedule
       in the past in Lake Tahoe.  Based on some past measurements,
       however, an average concentration has been estimated (McGauhey
       et al. 1963).  These values are:
          Nitrate as N    8 yg/1              Nitrite as N            1 yg/1
          Ammonia as N    2 yg/1              Organic nitrogen as N  50 pg/l
       There is considerable variation in nitrate during the year with
       depletion occurring in the euphotic zone.

**  5. Alkalinity range         40 - 45 mg/1           with mean = 43 mg/1

    6**Ca++ range: 8.8 - 9.9 mg/1             **Mq+ range: 2.1  - 2.9 mg/1
     **Na+  range: 5.8 - 7.0 mg/1             **K*  range: 1.6 - 1.8 mg/1
     **S04= range: 1.5 - 3.6 mg/1             **CT range: 1.7 - 2.1 mg/1
      *Fe   range: N-D-126 yg/1

**  7. Trace metals.  Where levels were below detection, the analytical
                                  474

-------
       limit is indicated (e.g.  Beryllium
       per liter.
                                   cO.3).  Values are in micrograms
Aluminum
Beryl 1 i urn
Bismuth
Cadmi urn
Cobalt
16
<0.3
<0.3
<0.7
<0.6
Chromium
Copper
Gallium
Germanium
Manganese

<0.07
trace
<2.8
<0.3
2.6

Molybdenum
Nickel
Lead
Titanium
Vanadium
Zinc
0.51
<0.3
<0.06
<0.6
15
<14
C.   BIOLOGICAL
    1.   Phytoplankton
        Representative profiles  of phytoplankton  biomass  and  productivity
        are shown in Fig.  2.
        * a.   chlorophyll  a_ ranges (unit is  mg/m^)
              epilimnion (0-15 m)      9.06 - 0.31
              euphotic zone (0-105 m)  0.03 -  1.25
                                            mean =0.18 for growing
                                            season
                                            mean = 0.275 for year
                                            round
      whole lake (0-400 m)    0.01 - 1.49                        3
  Maximum average concentration for the euphotic zone = 0.59 mq/m .
  Maximum average concentration for the whole lake = 0.39 mg/np.

* b. primary productivity (expressed as carbon)
     annual productivity = 55 g m~2 year~^ (average of 6 years)
     epilimnion (0-15 m) range 8.79 - 76.46 mg-day-1-m~2 (of
       epilimnion)
                   average = 38 mg-day~'-m~2 for growing season
     euphotic zone range 42 - 322 mg.m~2-day~1
                   average 150 mg-m~2.day~' (for 6 years)
  Note on Fig.  2 that the euphotic zone extends well below the
  depth at which 1% of surface light is transmitted.
  c. Algal growth is limited primarily by nitrogen and iron.  EDTA
  or NTA additions can effectively stimulate primary productivity
  through chelation.  Phosphorus is stimulating only when addi-
  tional nitrate is provided.
* d. There are over 160 species of phytoplankton in Lake Tahoe,
  112 of which are diatoms.   Only 10 are centric forms.  One of
  the dominant diatoms of the late 1960's Cyclotella bodanica has
  been replaced by Cyclotella stelligera.  Other dominant species
  include Dinobrypn sertularia, Fragilaria crotonens i s and Melosira
  crenulata.   As few as three species often account for 80% of
  the total phytoplankton biomass.  A large number of very small
  ~3y forms are now abundant at about 90 m in summer.   There tax-
          onomic  status  is  still  uncertain.
                                                 of the euphotic
          Phytoplankton  fresh  weight  biomass  =  8.3  g-m"
          zone  for  an  average  day  (average  of 2 years).
          The average  number of cell  concentration  is  about  100  cells  per
          milliliter.
                                  475

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          Duration of a "bloom"  at Lake Tahoe  is  about  3  to  4  months.   The
          time of its occurrence is highly variable  from  one year to the
          next, and it would  not be considered a  bloom  by most observers.

  * 2.   Zooplankton
        There is an average of about 1000 zooplankters  per cubic meter
        in Lake Tahoe.   The community is composed of about 25  species  of
        crustaceans and 14 species of rotifers.   It  is  dominated by the
        rotifers Kel1icottia  longispina, Ascomorpha  and Chromogaster
        and the copepods Epischura nevadensis  and Diaptomus  tyrrel1i.   The
        major pelagic cladocerans Daphnia and  Bosmina that were found
        often in Lake Tahoe have almost completely disappeared in recent
        years, perhaps from predation by the  introduced Mysis  relicta
        (Richards et al. in press).

    3.   Bottom Fauna
        The most abundant benthic animals are  sculpins  and the California
        crayfish Pacifastacus 1eniusculus. There are an  estimated 56
        million adult crayfish in the lake (Abrahamsson and  Goldman 1970).
        Aquatic oligochaets and  an endemic stone  fly are  also  abundant
        in some areas of the  lake.

    4.   Fish
        The fish fauna is largely composed of  exotic species.   These in-
        clude the lake trout, rainbow and brown trout as  well  as kokanee.
        Sculpins, suckers, and dace make up the rest of the  fauna.

    5.   Bacteria
        Bacteria are the usual pseudomonad varieties which.are often
        associated with detrital particles (see Paerl and Goldman 1972).
        Measurements of primary  productivity  in Tahoe together with
        measures of heterotrophy remain the most  important and sensitive
        indicators of eutrophication in the lake.
    6.   Bottom Flora
        Aquatic mosses, attached diatoms and  chara make up most of the
        benthic flora which grows to a depth  of 100  meters (Goldman and
        Amezaga 1974).

    7.   Macrophytes
        Some pond weeds are to be found in marinas and  protected areas.
        Higher aquatic plants are for the most part  absent in  the lake.


                          V.   NUTRIENT BUDGETS

Computations of nutrient budgets were based on the following:

Source from land runoff:

    1.   Total monthly water discharge calculated  from daily  measurements
taken by the U.S. Geological  Survey on nine major tributaries  of Lake
Tahoe.
                                  476

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    2.  The estimated yearly runoff of each of the other 54 creeks and
tributaries of Lake Tahoe (see Table 3-XV in McGauhey et al . 1963).  The
total monthly water discharge was estimated for these 54 creeks from this
yearly runoff and the measured discharge of the nine major tributaries.

    3.  Chemistry data collected on nine major tributaries by four dif-
ferent organizations.  The major data source was the Tahoe Research Group
of the University of California at Davis.  Other groups were:  The
California-Nevada Federal Joint Water Quality Investigation, Lake Tahoe
Area Council, Water Resources Information Series of the State of Nevada.

All chemistry concentration data were integrated monthly to get a mean
monthly concentration of nutrient per creek.

Creeks for which data for a specific month had not been collected were
assumed to have a concentration of nutrients equal to the average con-
centration of the other creeks that month.

For every creek the total amount of each nutrient that was discharged into
the lake was calculated for each month by multiplying the total flow data
by the mean concentration.  All creeks total discharge of nutrient were
summed by month and all monthly values summed to obtain the total load
of nutrients entering Lake Tahoe in one year from land runoff.  This
was done using 1969 data.

Precipitation

    1.  Average estimate total precipitation on the lake surface.

    2.  Measurements of average ammonium-nitrogen and nitrate-nitrogen
were made in the Lake Tahoe watershed (Coats, Leonard, Fujita and Goldman
in prep.) and various estimates have been made of total nitrogen content
of rain waters.  Only traces of phosphorus are assumed to be present in
the precipitation.

Groundwater

According to the water balance ground water does not contribute any sig-
nificant amount of water to the lake.
Waste Discharge

Waste is being diverted out of the basin.  Information on seepage is not
available, although exfiltration from sewer lines may be important.  High
nitrate runoff is still occuring from a temporary land disposal site at
South Tahoe (Perkins et al .  in press).
A.  PHOSPHORUS
                                             1            -21
                   Source            kg -year" '         g-m  -year"'

                Land runoff           23,404             0.047

                Precipitation         trace               —

                Total                 23,404             0.047
                                   477

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B.  NITROGEN (kg-year"1)

              Land Runoff        Precipitation*

N03-N           21,832               20,116

Organic N      104,645           no information

NH3-N           24,480                7,165              31,645

N02-N            2,731           no information

Total Nitrogen 153,688              104,000             257,288
                                                 ?      1
Total nitrogen surface area loading = 0.5156 g-m  -year  .

*A recent estimate for (N03-N + NH^-N) in precipitation was obtained
 using the water-year 1973-1974.  The new value is 49,900 kg-year"'.
 Preliminary results were obtained recently on measurements of organic
 nitrogen.  These,new results confirm that our preliminary value of
 104,000 kg-year"  is a very reasonable estimate of total nitrogen
 loading from precipitation, although it was not obtained by direct
 measurements.


                             VI.  DISCUSSION

     Lake Tahoe remains a classic example of a subalpine, ultraoligo-
trophic lake whose remarkable clarity gives record Secchi readings to
forty meters.  Oxygen shows no measurable depletion, even at depths of
500 meters, and the dilute rain of organic matter into the abyssal zone
is almost completely mineralized before it reaches the sediment.  The
lake, at present nitrogen levels, is rather insensitive to phosphorus
and can be considered a classic example of a nitrogen limited system.
It would appear to be highly sensitive to nitrogen loading and the in-
creased loading that has certainly accompanied the development of the
basin has caused an increase in primary productivity of about five per-
cent per year.


                              VII.  SUMMARY

     Because of its relatively small watershed and great volume Lake
Tahoe is at the extreme lower end of lakes classified on the basis of
loading.  In all probability this also makes it one of the lakes most
sensitive to nutrient loading.  Some confirmation of this is seen from
measures of primary productivity during the last 15 years (Fig.  3).  The
rate of increase appears to have peaked out during the last two or three
years, perhaps in response to the extensive sewage diversion from the
lake.  The loss of Daphnia and Bosminia as dominant zooplankters and
the increase of ultra plankton at the lower level of the euphotic zone
is of great interest.
                                    478

-------
        80,000-
        70.000H
    C\J
     i
     CP
     E
        60,0 OOH
        50,000-^
        40,000-j
        30,000

              1958  I960 1962 1964 1966  1968  1970 1972  1974  1976  1978 I960
Figure 3.  Annual primary productivity at Lake Tahoe between 1959-60 and
           1973.  Preliminary  results  indicate that the 1974 value is
           very close to the 1973  value for primary productivity.
                                   479

-------
                               REFERENCES
Abrahamsson, S.A.A.  and C.R.  Goldman.   1970.   The distribution, density
     and production of the crayfish Pacifastacus leniusculus (Dana) in
     Lake Tahoe, California-Nevada.  Oikos 21:83-91.

Court, J.E., C.R. Goldman and N.J. Hyne.   1972.   Surface sediments in
     Lake Tahoe, California-Nevada.  J.  Sediment. Petrol.  42:359-377.
Goldman, C.R.
     quality.
     408 p.
1974.  Eutrophication of Lake Tahoe emphasizing water
EPA-660-/3-74-034.   U.S. Gov. Printing Office, Washington.
Goldman, C.R. and E. de Amezaga.  1974.  Primary productivity of the
     littoral zone of Lake Tahoe, California-Nevada.  Proc.  Symp. Limnol.
     Shallow Waters, 15:49-62.

Goldman, C.R. and E. de Amezaga.  (In press).  Spatial and temporal changes
     in the primary productivity of Lake Tahoe, California-Nevada be-
     tween 1959 and 1971.  Verh. Internat.  Verein. Limnol. 19.

McGauhey, P.H., R. Eliassen, G. Rohlich, H.F. Ludwig and E.A. Pearson.
     1963.  Comprehensive study on protection of water resources of Lake
     Tahoe basin through controlled waste disposal.  Prepared for the
     Lake Tahoe Area Council.  Engineering-Scinece, Inc., Oakland,
     California.  157 p.

Paerl, H.W. and C.R. Goldman.  1972.  Stimulation of heterotrophic and
     autotrophic activities of a planktonic microbial community by sil-
     tation at Lake Tahoe, California.  Mem. 1st. Ital.  Idrobiol. 29
     Suppl.:129-147.

Perkins, M.A., C.R. Goldman and R.L. Leonard.  (In press).  Residual
     nutrient discharge in streamwaters influenced by sewage effluent
     spraying.  Ecology.

Richards, R.C., C.R. Goldman, T.C. Frantz and R. Wickwire.  (In press).
     Where have all the Daphnia gone?  The decline of a major cladoceran
     in Lake Tahoe, California-Nevada.  Verh. Internat.  Verein. Limnol. 19.
Smith, R.C., J.E. Tyler and C.R. Goldman.
     color of Lake Tahoe and Crater Lake.
                            1973.  Optical properties and
                            Limnol. Oceanogr. 18:189-199.
                                  480

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              REPORT ON NUTRIENT LOAD - EUTROPHICATION RESPONSE

                     FOR THE OPEN WATERS OF LAKE MICHIGAN


                 M.D. Piwoni, Walter Rast, Jr. and G. Fred Lee

                       Center for Environmental Studies
                         University of Texas at Dallas
                               Richardson, Texas


                                 INTRODUCTION
     Concern over the potential overfertilization of the waters of Lake Michigan
prompted the Water Pollution Control Administration (now the Environmental Pro-
tection Agency) and the states bordering on the lake to take action.  They
adopted regulations in 1968 that sought to reduce the phosphorus input from
waste treatment plants by 80 percent by December 1972.  In addition, the United
States and Canada have reached an agreement to reduce effluent phosphorus con-
centrations to 1.0 mg/1 for waters entering Lakes Ontario and Erie.  It is con-
ceivable that this requirement might also eventually apply to Lake Michigan.
This paper discusses the effects on loading that the reduction in effluent phos-
phorus has produced.  It also discusses the implications of this reduction on
water quality in the open waters of Lake Michigan.


                         PHOSPHORUS LOADING ESTIMATES

     Lee (1974) compiled the phosphorus loadings to Lake Michigan in 1971 using
a report by the Phosphorus Technical Committee to the Lake Michigan Conference
(Zar, 1972).  The total estimated loading of phosphorus from all sources was
18.1 million pounds per year (Table 1) .  This is somewhat  higher than the values
estimated by Bartsch (1968), by US EPA report (1971), and by the Region V Office
of the Environmental Protection Agency (Zar, 1972).  However, these latter esti-
mates probably do not include storm sewer overflow or direct precipitation and
dry fallout contributions (see Table 1).

     Lee (1974) also included predicted phosphorus loading to the lake for 1973
which incorporated the 80 percent reduction in phosphorus by waste treatment
facilities in the basin that was agreed to in the late 1960's by the states
bordering on Lake Michigan.  This value, included in Table 2, assumes 13.2
million pounds of phosphorus yields 2.6 million pounds per year of phosphorus,
which leads to the 7.5 million pounds per year total loading of phosphorus
shown in Table 2.  This predicted phosphorus loading of 7.5 million pounds per
year is expected to be reached by approximately 1976-77, assuming the projected
goal of 80 percent removal of phosphorus from domestic wastewaters is attained.
This would place Lake Michigan in an oligotrophic category (Figure 1) relative to

                                      481

-------
           Table 1.   ESTIMATED PHOSPHORUS LOAD
                 TO  LAKE MICHIGAN, 19711
      Source                                Load
                                       (Million Ibs/yr)

 Direct wastewater                       3.9
 Indirect wastewater                     9.3
              Total wastewater          13.2

 Erosion and other diffuse sources       3.0 (1 to 7)
 Combined sewer overflow                 0.8
 Precipitation and dustfall on           1.1
   surface of lake
              Total diffuse source       1.9

 Total                                  18.1

 Bartsch 1968 Estimate                  14.6
 US EPA 1971 Estimate                   14. 3
 Zar 1971 Estimate                      16.7
XAfter Lee (1974).
                          482

-------
         Table 2.  ESTIMATED PHOSPHORUS LOADING
                 TO LAKE MICHIGAN, 1974
   Source                                   Load
                                       (Million Ibs/yr)
1 2
Wisconsin contribution '
3
Michigan contribution
i 4
Indiana*
Illinois5'"'5
Combined sewer overflow
Precipitation and dustfall
Total
Lee Estimate for 1973
4.5
4.7
0.6
0.7
0.8
1.1
12.4
7.5
 (assumes 80 percent P removal from
  domestic wastewaters)
IJC Goal for 19737                          11.7
l32From Schraufnagel (1974) and Wisconsin DNR report (1973)
   From McCracken (1974).
4  From Miller (1971).
5  From US EPA (1971).
c
   From Lee (1974).   Based on 80 percent removal.
7
   From Great Lakes  Water Quality Board (1973).
"  Tributary input of phosphorus into Lake Michigan,
   1970 data.
** Represents  1971 data.
                          483

-------

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Vollenweider's (1975)  loading criteria  (the  effects  of  differ-
ent hydraulic residence times in  assessing the  trophic  status
of Lake Michigan is discussed in  a  following section).   Vollen-
weider (1975) has used this  relationship  (Figure  1)  to  indicate
the relative trophic status  of a  large  number of  lakes  based
on phosphorus loadings and mean depth and hydraulic  residence
time.
Table  2 also includes  the best available  estimates for  phos-
phorus loadings to Lake Michigan  as of  January, 1974.  The
pollution control agency of  each  of the states  bordering on
Lake Michigan was contacted  for updated information  on  nutrient
sources.   These values are based  on information provided by
each state.   Values for Michigan  and Wisconsin  reflect  improved
phosphorus removal by  sewage treatment  plants by  the end of
1973.   Current values  for Indiana and Illinois  were  not avail-
able.   The values for  these  states  presented in Table 2 are
probably somewhat high.
If one assumes that the decrease  in phosphorus  loading  from
1971 to 1973 was due entirely to  improved sewage  treatment
plant phosphate removal, then the 1973  estimates  reflect a
43 percent reduction  in  this  source of phosphorus,  based on
Lee's  (1974)  estimates.
Without any phosphorus  removal from domestic wastewaters or
a change  from phosphorus  to nonphosphorus-type detergents,
it would  be expected  that approximately  30  million  pounds
of phosphorus per  year would  be  entering the lake by the
year 2020 over what was  expected to enter Lake Michigan in
1973.   This would  make  the  2020  loading approximately  42.2
million pounds of  phosphorus  annually.  This would  place
Lake Michigan in a eutrophic  or  eutrophic-mesotrophic  status,
depending on the hydraulic residence time used in calculation
of the 2/T  term in the  Vollenweider diagram,  relative to its
          U)                             to    5
phosphorus loading (Figure 1).   However, since the  wastewaters
will be treated for at  least  80-90 percent  phosphorus  re-
                              485

-------
moval , only a 2.4 million pound increase per year (assuming 90
percent removal) in the phosphorus loading from the sewered
population is expected by the year 2020.
This will be countered by a combination of diversion of
sewage and elimination of combined sewer overflow (Table 3a)
with the result that the new change in phosphorus loading
to Lake Michigan between 1973 and 2020 is expected to be only
about 2.1 million pounds per year (Lee, 1974).  This is a
total phosphorus loading to Lake Michigan of 9.6 million pounds
per year by the year 2020.  This would leave Lake Michigan in
an oligotrophic status relative to the Vollenweider (1975)
plot (Figure 1), regardless of whether 30 or 100 years is
taken as the hydraulic residence time, even with the 2.1
million pound per year increase in phosphorus load.
The nitrogen loading to the lake was estimated by Bartsch (1968)
to be about 166 million pounds per year.  It is not expected
that the nitrogen loadings would have changed much since 1968.

PROBLEMS IN ESTIMATING NUTRIENT LOADS

The estimates presented in Tables 1 and 2 are necessarily
based on a number of assumptions.  Much of the wastewater data
is calculated using 3.6 pounds of phosphorus per person per
year.  For direct wastewater sources (i.e., discharge directly
into the lake), this value is probably quite good, but for in-
direct sources (i.e., discharge to a tributary to the lake), it
is probably too high.  No attempt was made to determine what
percentage  of the phosphorus from indirect wastewater sources
is actually reaching the lake in an available form.
Diffuse source estimates were based on an average contribution
per square mile of watershed area, usually about 100 pounds of
phosphorus per square mile per year:  These assumptions, although
the best available at this time, result in considerable uncer-
tainty in the loading estimates.

                            486

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     Table 3a.   EXPECTED CHANGES IN PHOSPHORUS LOADING
                OF LAKE MICHIGAN, 1973-2020a
 Factors Influencing
 Future Phosphorus Load
 Change in Load
 (Million Ibs/yr)
 Diversion of North Shore Sanitary
   District
 Eliminate Combined Sewer Overflow
 Increase in Sewered Population
  (90 percent phosphorus removal by
   year 2020)
 Increased Urban Area (conversion of
  rural to urban land)
 Rural Runoff Input Reduction
 Urban Runoff Input Reduction
 Improvement in Advanced Waste
  Treatment
       Net Change in Phosphorus Load
       to Lake Michigan, 1973-2020
     -0.1
     -0.8

     + 2.4

     + 0.6
magnitude unknown
magnitude unknown

magnitude unknown

     + 2 .1
From Lee (1974)
                         487

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PROBLEMS IN ESTIMATING THE HYDRAULIC RESIDENCE TIME FOR LAKE
MICHIGAN
For the purposes of this discussion, and as it is used in the
Vollenweider phosphorus loading diagram (Figure 1), the hydrau-
lic residence time is defined as the water body volume/annual
inflow volume.  Thus, it constitutes the water body's "filling
time."  If the annual precipitation onto the water body surface
was approximately equal to its annual evaporation, the annual
outflow volume could be used in the same manner as the inflow
volume.  There are advantages to both methods.  The necessity
of having to account for precipitation and evaporation in
calculation of the hydraulic residence time is avoided if the
inflow volume is used.  However, the inflow to a water body
is frequently through numerous tributary inputs , as well as
from runoff directly into the water body and precipitation
directly onto the water body surface.  It is usually difficult
to measure accurately all such inflows to a water body.  By con-
trast, the outflow for most water bodies is usually through a
single outlet, allowing it to be more easily measured.  The out-
let is often gaged and, therefore, the computed total outflow
is usually more accurate than the total inflow.  Since several
methods were possible, it was decided early in the US OECD study
that the hydraulic residence time of the US OECD water bodies
would be determined on the basis of their annual inflow volumes
(Jaworski, 1974).
For Lake Michigan, an examination of the literature indicates
there is considerable confusion concerning its hydraulic resi-
dence time.  Most investigators used the outflow or discharge
volume rather than the inflow volume to calculate Lake Michigan's
hydraulic residence time.  Because precipitation is approximately
equal to evaporation, calculation of the hydraulic residence time
using the outflow volume will give a reasonable estimate of its
magnitude.  A summary of the reported hydraulic residence times
for Lake Michigan is presented in Table 3b.   In some  cases,  the
hydraulic residence time was stated by the investigators, while
                             488

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     Table 3b.  SUMMARY OF HYDRAULIC RESIDENCE TIMES
                REPORTED FOR LAKE MICHIGAN
Hydraulic Residence
     Time (yr)                  Source of Information
       99. 4                  Beeton and Chandler (1963)
       30.8                  Rainey (1967)
       31.2                  Patalas (1972)
                             Vollenweider and Dillon (1974)
       31.2                    a) Table 1
      100                      b) Figure 2
      94-113                 Vollenweider (1975, 1976, 1977a)
       30                    Watson (1976)
      105                    International Joint Commission
                               (1976)
       30                    Sonzogni  et_ al.  (1976)
      100                    Schelske  (1977)
      100                    Bennett (1977)
                          489

-------
in other cases it was calculated by these reviewers based on the
data presented by the indicated sources.   Examination of Table 3b
indicates that, with one exception, the hydraulic residence time
estimates for Lake Michigan aggregate around the two values of
30 and 100 years, depending on the source of the data.   There
are several reasons for this three-fold difference in the hy-
draulic residence time estimates.   One reason is that previous
investigators have not adequately defined their terms.   They did
not clearly indicate whether annual inflow or outflow volumes
were used in their calculations.  However, this factor alone is
not sufficient to account for the large differences in the re-
ported hydraulic residence times for Lake Michigan.
Recently, Quinn (1977) has conducted a study of the annual and
seasonal flow variations through the Straits of Mackinac from
Lake Michigan to Lake Huron.  While Lakes Michigan and Huron
have historicallv been treated as a single body of water in
hydraulic  and  hydrologic  studies, Quinn has  indicated that the
actual  water mass transport between these two  lakes has generally
been  ignored.   Consequently, Quinn developed a water mass con-
tinuity technique which he applied to Lake Michigan for the
1950-1966  period to determine average annual and monthly flows
through the Straits of Mackinac.  His model  indicated a 500+
percent  variation between maximum and minimum  annual flows
through the straits during the  17-year period.  He also compared
his predicted  flows with the results of a direct current mea-
surement of flow through the straits for a 100-day period in
1973  and found  the results agreed within 2 percent.  Using his
technique, the  annual variations and seasonal  cycle of the flow
through the straits were quantified.  Based  on his study, Quinn
has determined  that calculation of two different hydraulic re-
sidence  times  is possible for Lake Michigan.   If the annual
mean  flow, with no regard for seasonal variations, is used in
the computation of the hydraulic residence time, Quinn obtains
a  value  of 137  years.  However, Quinn also found that there is
a  deep  return  flow of water into Lake Michigan through the
straits  during  stratification.  If this return flow is considered
                            490

-------
in the computations as part of the annual inflow water volume,
a hydraulic residence time of 69 years is obtained.  This value
of 69 years falls approximately in the middle of the 30-100
year range reported in Table 3b.
There is mixing of this "backflow water" with the water at the
upper end of Lake Michigan, although the extent of this mixing
is not known.  It is likely that the backflow has limited effect
on the waters of lower Lake Michigan, but it influences the dis-
charge through the Straits of Mackinac into Lake Huron.  Because
of the uncertainty concerning the correct value, both the 30 and
100-year hydraulic residence time values were used in calcula-
tion of the mean depth/hydraulic residence time term (i.e.,
Z/T ) in the Vollenweider phosphorus loading diagram (Figure 1).
A value between these two extremes is likely the correct hydrau-
lic residence time for Lake Michigan (e.g., Quinn's (1977) value
of 69 years).  Consequently, 30-100 years can be used as a range
of the hydraulic residence times, depending on the actual out-
flow volume of Lake Michigan during a given year.  The use of
100 years in the Z/T  expression produces a value of 0.8U m/yr,
while 30 years produces a Z/T  value of 2.8 m/yr.  However, it
should be noted that while 30-100 years was used as a range for
the hydraulic residence time values in this report, based on the
work of Quinn (1977), a range of 70-100 years is likely a more
realistic estimate of the present hydraulic residence time for
Lake Michigan.
The effect of these two hydraulic residence time values (i.e.,
30 and 100 years) on the relative position of Lake Michigan on the
Vollenweider diagram can be seen in Figure 1.  AT  value of 100
years indicates Lake Michigan was in the mesotrophic zone of the
Vollenweider diagram, based on its 1971 phosphorus load, and is
approximately at the oligotrophic-mesotrophic boundary, based
on its 1974 phosphorus load.   This characterization of Lake Mi-
chigan is reasonable for its nearshore water zones, but is not
indicative of the open water trophic conditions of the lake,
which are generally considered as oligotrophic.  A T  value of
                             491

-------
30 years indicates Lake Michigan plots at the oligotrophic-meso-
trophic boundary in 1971 and in the oligotrophic zone of the
Vollenweider diagram in 1974.  This oligotrophic characteriza-
tion is accurate for Lake Michigan's open waters, but does not
describe its nearshore zones, which are in a relatively more
productive condition than its open waters.  Thus, the effects
of the two T  values make a difference in delineation of Lake
            OJ
Michigan's predicted trophic condition, as indicated by its
position on the Vollenweider phosphorus loading diagram (Fig-
ure 1).  The lower 1974 phosphorus load to Lake Michigan, re-
lative to its 1971 load, implies an improvement in its water
quality, as indicated by its more oligotrophic position on the
Vollenweider diagram (Figure 1).  Such an improvement is likely
when Lake Michigan has reached a new equilibrium condition
relative to its reduced phosphorus loading (Sonzogni et al. ,
1976) .

NUTRIENT LOADS AND PRODUCTIVITY IN LAKE MICHIGAN

Schelske and Callendar (1970) surveyed the phytoplankton
productivity and the nutrient levels of Lakes Michigan and
Superior during the summer of 1969.  Table 4 contrasts data
for nutrient and productivity parameters for the two lakes,
Productivity, as measured by carbon fixation, is about eight
times  greater in Lake Michigan than in Lake Superior.  Con-
versely, SiO~ concentrations are considerably lower in Lake
Michigan because of the larger diatom population.  Schelske
and Callendar (1970) suggest that the large difference in Si02
concentrations between surface and bottom waters in Lake
Michigan also indicates a substantial diatom population,
NO_-N  is higher in Superior and shows little concentration
                                 +               =
change down the water column.  NH -N and ortho-PO -P show no
apparent correlations but are included in Table 4 to facilitate
comparison.  A summary of nutrient loadings and productivity
characteristics is presented in Table 5.

                             492

-------











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       Table 5.   LAKE MICHIGAN SUMMARY OF PRODUCTIVITY
            AND NUTRIENT LOADING CHARACTERISTICS
Loading values
            1                           2
  Phosphorus  (total)            0.1 g/m /yr
          2                             2
  Nitrogen  (total)              1.3 g/m /yr
Productivity3'4                  3.4 mg-C/m3/hr
                                 150 g-c/M2/yr

Yearly average
               3                         3
  chlorophyll a               '2.3 mg/m
Euphotic zone                    8   meters
Mean depth                       84  meters
Mean water residence time        30 - 100 years
   From this report.
  2After Bartsch (1968).
   After Schelske and Callender (1970).
  4After Vollenweider (1975).
                             494

-------
According to the Vollenweider  (1975) phosphorus loading  diagram,
the current phosphorus loading to Lake Michigan places it  in  the
oligotrophic zone of the diagram, below its "permissible"  loading
line, regardless of whether the 30 or 100 year hydraulic residence
time value is used (Figure 1).  Table 5 contains loading estimates
as well as the mean depth and hydraulic residence times  used  in
the Vollenweider diagram.  This trophic classification is  roughly
in agreement with the productivity status of the open waters  of
this lake.  Further reductions in the phosphorus loading to the
lake would tend to move Lake Michigan to a relatively more "oligo-
trophic" position on the Vollenweider diagram.  Table 5 also con-
tains values for productivity, yearly average chlorophyll  a, and
the depth  of the euphotic zone in the open waters of Lake  Michigan.

                IMPACT OF NUTRIENT REDUCTION
              ON WATER QUALITY IN LAKE MICHIGAN

 Three more or less distinct regions of the lake must be  con-
 sidered  in evaluating the potential impact that 80 to 90
 percent  phosphorus removal from domestic wastewater will have
 on water quality in Lake Michigan.   These are the open waters
 of the lake (which are the primary focal point of the report),
 the nearshore waters, and the areas of restricted circulation
 such as  river mouths, harbors, etc.  Lee (1974) has discussed
 the characteristics of each of these regions and the probable
 impact which 80 to 90 percent phosphorus removal from domestic
 wastewaters will have on water quality in each of these  areas.
 As pointed out by Lee (1974), there will likely be a small
 improvement in water quality in the open waters of the lake
 which should be manifested several years from now in the form
 of reduced phytoplankton growth.  The greatest improvement in
 water quality will likely occur in the nearshore waters  where
 phosphorus is already or can be made the limiting factor con-
 trolling planktonic and attached algal growth.  As noted by
 Lee (1974), in areas of restricted circulation such as southern
 Green Bay, little or no improvement in water quality will
                             495

-------
likely occur from the 80 percent removal of phosphorus from
domestic wastewater sources, since it would be insufficient to
make phosphorus the limiting element controlling algal growth
in these areas.
From an overall point of view, the information available today
strongly supports the decision that was made in the late
1960's by the federal government and the states bordering on
Lake Michigan to provide for 80 percent removal of phosphorus
from domestic wastewater sources.  Failure to take this step
would have resulted in a very significant deterioration of
water in Lake Michigan due to the increased urbanization of
the lake's watershed.  Instead of the steady, slow decline in
water quality of the lake which would have resulted without
the removal of phosphorus from domestic wastewaters, water
quality in this lake should improve in the next 50 years due to
the decision that was made in the late 1960's bringing about
phosphorus removal from domestic wastewaters.


                       ACKNOWLEDGEMENTS

 The primary source of information which served as the basis
 for this paper is a report by the Phosphorus Technical Com-
 mittee to the Lake Michigan Enforcement Conference, H. Zar,
 Chairman.  The information provided in this report was up-
 dated through the assistance of F.  Schraufnagel,  State of
 Wisconsin, and C. Fetterolf, State of Michigan, as well as
 several individuals from the State of Illinois and the
 International Joint Commission, Windsor, Ontario.  The
 assistance of these individuals is greatly appreciated.
                             496

-------
                          REFERENCES
Beeton, A.M. and D.C. Chandler.  1963.  The St. Lawrence Great
   Lakes.  In: D.G. Frey (ed.), Limnology in North America,
   University of Wisconsin Press , "Madison .  p~pT]535-558"!

Bennett, H.W.   1977.  Letter to G.K. Rodgers, Canada Centre
   for Inland Waters, Burlington, Ontario, dated April 14, 1977.


Dillon, P.J.  1975.  The Phosphorus Budget of Cameron Lake,
   Ontario:  the Importance of Flushing Rate to the Degree of
   Eutrophy of Lakes.  Limnol. Oceanogr.  2 Ch 2 8 - 3 9 .

Frey, D.G.  Limnology in North America.  University of Wisconsin
   Press, Madison.734 pp.

International Joint Commission.  1976.  Further Regulation of
   the Great Lakes.  International Joint Commission Report to
   the Governments  of Canada and the United States.  96 pp.

Jaworski, N.A.  1974.  Personal Communication - US EPA, National
   Environmental Research Center, Corvallis.  October 8, 1974.

Patalas , K.  1972.   Crustacean Plankton and the Eutrophication
   of the St. Lawrence Great Lakes.  J. Fish. Res. Bd. Can.
   29 :1451-1462.

Quinn, F.K.  1977.   Annual and Seasona] Variations Through the
   Straits of Mackinac.   Water Resources Research 13:137-144.

Rainey, R.H.  1967.  Natural Displacement of Pollution From the
   Great Lakes.   Science 155:1242-1243'.

Schelske, C.L.   1977.  Personal Communication - Great Lakes
   Research Division, the University of Michigan, Ann Arbor,
   Michigan.  January 31, 1977.

Sonzogni, W.C.,  P.D.  Uttormark and G.F. Lee.  1976.  Phosphorus
   Residence Time Model:  Theory and Application.  Water Research
   10:429-435.
                              497

-------
 Vollenweider,  R.A.  and  P.J. Dillon.  1974.  The Application of
    the  Phosphorus  Loading  Concept to Eutrophication  Research.
    National  Research  Council  Canada Report No. 13690.   42 pp.

 Vollenweider,  R.A.  1968.  Scientific  Fundamentals of the
    Eutrophication  of  Lakes and  Flowing Waters, with  Particular
    Reference to  Phosphorus and  Nitrogen as Factors in Eutrophica-
    tion.   OECD Tech.  Report DAS/CSI/68.27, Paris.  159  pp.

Vollenweider,  R.A.  1975.  Input-Output Models.  Schweiz.  Z.
   Hydrologie . 3T_: 53-84.

Vollenweider,  R.A.  1976.  Advances in Defining Critical Loading
   Levels for  Phosphorus in Lake Eutrophication.   Mem.  1st.  Ital .
   Idrobiol. 3j3:53-83.

Vollenweider,  R.A.  1977a.   Personal Communication -  Canada  Centre
   for Inland  Waters,  Burlington, Ontario, January 13,  1977.
                                  *
Vollenweider,  R.A.  1977b.   Personal Communication -  Canada  Centre
   for Inland Waters,  Burlington, Ontario, February 10,  1977.

Watson, A.P.   1976.  Personal  Communication - International  Joint
   Commission, Windsor, Ontario, December 13, 1976.
                              498

-------
                 TROPHIC STATUS AND NUTRIENT LOADING

                          FOR LAKE MICHIGAN

                          Claire L. Schelske

                     Great Lakes Research Division
                         University of Michigan
                          Ann Arbor, Michigan


                             INTRODUCTION
Lake Michigan is the world's sixth largest lake in terms of volume or
surface area (Hutchinson 1957).  Limnologically it has not been studied
extensively.  Studies on lakewide eutrophication, with the exception of
fisheries, are relatively recent (Beeton 1965; Ayers and Chandler 1967;
Beeton 1969).  Limnological characteristics have been summarized and
compared with other Laurentian Great Lakes by Beeton and Chandler (1963)
and Schelske and Roth (1973).  The lake serves many uses including munic-
ipal and industrial water supply, recreation, transportation, and com-
mercial and sport fishing (Beeton and Chandler 1963; Beeton 1969).

The purpose of this paper is to review the effects of nutrient loading
on biological communities and processes and to assess current and past
trophic conditions in Lake Michigan.  In this paper, the classical
definition of oligotrophic and eutrophic will be used, i.e. that the
terms imply variation in nutrient content.  Eutrophication therefore
results from nutrient enrichment or more specifically from increased
supplies of limiting nutrients.

The discussion of nutrient loads for Lake Michigan is the subject of a
separate paper by Piwoni, Rast and Lee in this volume.

Phytoplankton growth and primary production in Lake Michigan are limited
by supplies of phosphorus, an environmental characteristic common to
Lake Superior and Lake Huron as well.  Evidence to support this state-
ment is available from numerous field and laboratory experiments
(Schelske and Stoermer 1972; Schelske et al. 1972; Schelske et al. 1974;
Schelske, Simmons and Feldt, In press).  It has also been shown that
supplies of nitrogen have little if any effect on phytoplankton growth
                                  499

-------
(Schelske et al. 1974).  Other evidence for control of eutrophication by
inputs of phosphorus in the Laurentian Great Lakes is provided by data
that show concentrations of phosphorus increase as primary productivity
and chlorophyll a increase and Secchi disc transparency decreases
(Fig. 1).  Concentrations of chlorophyll a from the open-lake stations
are lowest in Lake Superior, larger in Lake Huron, and largest in Lake
Michigan, with phosphorus having the same relationship among the three
lakes.  These results clearly show that standing crops of algae (measured
by concentrations of chlorophyll a) are positively correlated with
concentration of phosphorus in the water.  There also is nearly an order
of magnitude range in rates of primary productivity for Lake Superior,
the most oligotrophic of the lakes, and Lake Michigan.

Historical data on trends in levels of nutrients are not available, but
ample evidence exists that conservative elements have increased (Beeton
1965) .  Whether changes in levels of conservative elements affect trophic
state is an unresolved question.
                        INSHORE-OFFSHORE DIFFERENCES

Investigations of Lake Michigan, particularly the southern half, have
revealed extreme differences in nutrients, phytoplankton productivity and
standing crop between the nearshore waters and the open parts of the lake
(Ladewski and Stoermer 1973; Stoermer 1972).  Maximum chlorophyll a
concentrations and standing crops of phytoplankton in the spring were
15 mg/m-3 and 8,000 cells/ml in the nearshore waters, several times great-
er than the offshore waters.  In the spring during the presence of the
thermal bar these differences may not be surprising since the nearshore
area may be 6-10°C warmer than the offshore region; but these differences
persist throughout the year so factors other than temperature are
important (Holland and Beeton 1972) .  Nutrient input from rivers obvious-
ly contributes to the inshore-offshore differences, and this factor is
important to consider since the input is not distributed uniformly over
the lake.
                                  500

-------
100
 50
 10
 1.0
0.5
O.I
I

\
    1


Chlorophyll a

Primary  Productivity
Total  P

Secchi Disc
     Lake Erie
      Western
       Basin
              Lake
            Michigan
       Lake
      Huron
  Lake
Superior
 Figure 1.  Chlorophyll a (mg/m^) , primary productivity
 (mg C/m^/hr),  total phosphorus (mg PO^-P/m^) and Secchi disc
 transparency (m) in the Great Lakes.  (From Schelske 1974.)
                         501

-------
No estimates of differences in nearshore nutrient loading have been made,
but the significance of unequal loadings is obvious from data on nutrient
input by various tributaries.  Forty percent of the nutrient loading as
total soluble phosphorus occurs on about five percent of the shoreline or
from the input of the Muskegon, Grand, Kalamazoo, and St. Joseph rivers
along the southeastern part of the lake.  Another 35 percent is contrib-
uted by the Fox and Menominee rivers flowing into Green Bay, leaving
only 25 percent of the loading for the remainder of the nearshore zone
(Schelske 1974).

It is obvious that the effects of nutrient loading to Green Bay are
manifested primarily in the bay and do not affect greatly the water
quality in the northern part of Lake Michigan.  Evidence for this state-
ment is based primarily on the fact that the chemical and biological
characteristics in northern Green Bay are very similar to those found in
northern Lake Michigan (Schelske and Callender 1970).  The nutrient
contribution from Green Bay to northern Lake Michigan is therefore
diffuse and represents only a relatively small, if any, source of nutri-
ent enrichment for the open-lake waters.  If there is a difference in
nutrient composition, the loading factor might be significant due to the
relatively large volume of water flowing out of Green Bay into Lake
Michigan.

Due to the large difference in nutrient loading within the nearshore zone
and between the nearshore zone and the offshore zone, it will not be
possible to discuss the nearshore zone in this paper.  The nearshore zone
is also much more variable biologically than the offshore zone.  This
restriction is not too serious when one considers nutrient loading for
the system, since the nearshore zone divided arbitrarily at the 20-m
contour represents a small fraction of the lake (Table 1).
                                  502

-------
Table 1.  MORPHOMETRIC AND HYDROLOGIC CHARACTERISTICS OF LAKE MICHIGAN.

Nearshore
Depth (m) 0-20
Length (km)
Breadth (km)
2
Water surface (km ) 7,440
2
Land drainage basin (km )
2
Land and water (km )
Maximum depth (m) 20
Average depth (m) 10
3
Volume of water (km ) 74
3
Mean outflow (km /yr)
Offshore Lake
20-281 0-281
490
188
46,110 53,550a
117,840
170,390
281 281
97.5
4,796 4,870
49.1
  Excluding Green Bay.
                     GENERAL MORPHOMETRY AND HYDROLOGY

Lake Michigan is deep, with a maximum depth of 281 m, and has two prin-
cipal basins, the northern and the southern.  The long axis is 490 km in
a nearly north-south direction (Fig. 2).  Morphometric and geological
characteristics have been described by Hough (1958) and geological
research has been reviewed by Sly and Thomas (1974).  The drainage basin
is large, 170,390 km2 with the lake occupying one-third of the surface
area (Table 1).  Because of the large proportion of lake surface to
drainage area, inputs of water and nutrients from precipitation directly
on the lake surface are significant.  The other large input of water is
surface runoff from streams and rivers, although ground water inflow may
be an important consideration in local areas.  Water is lost mainly
                                  503

-------
                       Rapid R   Wfutefish R.
                 Escanaba R.
GREEN  BAY


   Fox

  Manitowoc R


  Sheboygan R.
 Milwaukee R


 MILWAUKEE
                                                 Boardman R.
                                     .UDINGTON
                                       Pere Marquette R.
                                                         STRAITS
                                                           AREA
                                          Muskegon R
                                         RAND HAVEN
                                          Kalamazoo R.
                                      St. Joseph R.
Figure 2.  Major tributaries of Lake Michigan.  (From Schelske
1974.)
                              504

-------
through evaporation and the main outflow at the Straits of Mackinac
(Table 1).  A small amount of water in relation to the outflow (3 km^/yr)
is used to supply water for the city of Chicago and is not returned
because waste water is diverted to the drainage system of the Mississippi
River through the Chicago Sanitary Canal.
                      PHYSICAL AND CHEMICAL CONDITIONS

Areas of all five Laurentian Great Lakes are extensive so meteorological
factors, particularly wind energy, can produce large-scale physical
changes resulting in seiches, upwelling, and surface and subsurface
currents.  Two recent review papers provide excellent treatments of
physical processes of large lakes (Mortimer 1974; Boyce 1974), but few
studies have been made on how these physical processes influence chemical
or biological processes.  Physical characteristics are determined by the
facts that the basins are closed and large enough so water transport is
affected by Coriolis force (rotation of the earth),  wind is the princi-
pal source of mechanical energy, and the water is thermally stratified
in the summer (Boyce 1974).

Surface currents generally behave as expected due to the influence of
Coriolis force with movement in a counterclockwise direction, i.e.
currents moving south on the western shore and north on the eastern shore,
The mean surface currents indicate two and possibly three cells or areas
of counterclockwise circulation along the long axis of the lake (Millar
1952).  Ayers et al. (1958) found this general pattern during periods of
the normal westerly winds in June but not in August when winds were more
easterly.  It is well known that circulation patterns are transient and
can change within a day, given normal shifts in wind speed and direction.

The thermal structure and stratification differ from either first-class
or second-class temperate lakes, described by Hutchinson (1967) .  Lake
Michigan is an atypical temperate lake in that it is not truly dimictic
but is probably monomictic.  After thermal stratification breaks down in
                                   505

-------
the fall, the lake does not stratify again until the next summer, mixing
at least periodically during storms all winter.  Due to the long fetch
and mixing in the winter, the entire water mass cools to less than 4.0°C
with temperatures as low as 0.5°C being common in mid-lake during March
(Rousar 1973).  Investigators have observed inverse thermal stratifica-
tion after the water has cooled below 4.0°C—the warmer water remains on
the bottom until the lake is mixed completely by a storm.  Very unusual
winter cgnditions are needed for the lake to freeze completely for
extended periods of time, but ice formation is extensive in shallow
waters.  Temperature ranges in the open lake are at least 0.5-22.9°C
(Rousar 1973).

In addition to being monomictic, Lake Michigan differs from shallower
temperate lakes in that spring warming produces a thermal bar in the
lake.  This phenomenon has been well described previously for other large
lakes and for the Laurentian Great Lakes, by Rodgers (1965) for Lake
Ontario, by Huang (1972) for Lake Michigan, and generally by Mortimer
(1974) .  Differential warming in the spring produces the thermal bar;
nearshore waters being shallower warm more rapidly than the deeper off-
shore waters.  The thermal bar is the downwelling water at maximum
density (4.0°C) that develops between water nearshore that is warmer and
water offshore that is colder than 4.0°C.  This sharp horizontal temper-
ature gradient restricts mixing of inshore waters with the open lake and
affects biological problems related to nutrient loading.  Different and
greater numbers of phytoplankton were present on the shoreward side of
the thermal bar (Stoermer 1968).

Seasonal, physical and chemical data are available from Rousar (1973).
These data are summarized in Table 2 as they are the most extensive data
set available for open-water conditions during an entire year.  These
data also appear to represent chemical conditions during 1970-1971
because results available from other investigators sampling at the same
time are comparable in magnitude.
                                   506

-------
 Table 2.  PHYSICAL AND CHEMICAL DATA FOR LAKE MICHIGAN WATER COLLECTED
     FROM A DEPTH OF 4 METERS.  Nearshore values are Station 1 near
     Milwaukee and offshore values are for Stations 3 and 4 between
   Milwaukee, Wise, and Ludington, Mich.  Data presented are averages
             and ranges for an 18-month period in 1970-1971.
                      Data are from Rousar (1973).
                                      Nearshore
                        Offshore
Temperature (C)

PH

Total alkalinity (meq/liter)

Specific conductance
 (ymhos/cm @ 25 C)

N03-N (mg/liter)

Si02 (mg/liter)

Total P (pg/liter)

Soluble reactive P (pg/liter)
11.4 (0.1-20.8)

 8.3 (7.9-8.8)

2.14 (2.06-2.25)


 265 (257-278)

0.19 (0.10-0.29)

0.75 (0.2-1.6)

15.2 (8.2-32.9)

 1.9 (ND-10.8)
11.4 (0.5-22.9)

 8.3 (8.1-9.0)

2.12 (2.04-2.17)


 259 (251-273)

0.19 (0.12-0.27)

0.85 (0.2-1.5)

 8.1 (2.4-16.0)

 1.1 (ND-4.0)
A distinct difference is obvious in the total phosphorus concentrations

between nearshore and offshore, but there is no difference in the
averages for the other parameters (Table 2).  The lack of significant
differences is due partly to the technique of averaging, partly to the
parameters listed, and partly to the locations of the stations.

Distinct differences between offshore and inshore stations were obtained
for Secchi disc transparency during two years of intensive sampling

(Fig. 3).  The transparency varies seasonally and, with the exception of
the minimum in September, was correlated inversely with cell counts and

chlorophyll concentrations (Ladewski and Stoermer 1973).  September

transparency was reduced by upwelled light from "milky water," probably

suspensions of precipitated calcium carbonate.
                                   507

-------
   10
X
>-
a.
Ul
Q
                                              \'  I  \/  •'     ••X--H
                                            Kr  KY -•       »-U
        May    July   Sept   Nov
                  1971
May    July   Sept   Nov
          1972
Figure 3.  Secchi disc transparency averaged by  depth  range and month.
Key:  Dotted line shows mean value for  stations  less than 10 m deep,
dashed line shows mean value for stations  between  10 m and 40  m deep  and
solid line shows mean value for stations deeper  than 40 m.  For each
cruise there are nominally 12 stations  shallower than  10 m, 16 between
10 and 40 m deep and 13 deeper than 40  m.   Error flags show the standard
error of the mean.  (From Ladewski and  Stoermer  1973.)
"Milky water" is associated with increases  in pH of  surface  waters  dur-
ing summer.  Maximum open-water values for  pH are now much greater  in  the

summer than 8.0-8.2 commonly cited in many  papers, as pointed out
previously by Schelske and Roth (1973).   This fact is confirmed by  the

maximum pH of 9.0 recorded by Rousar (Table 2).   Data for the conserva-

tive elements and representative values  for a number 'of  the  trace

elements are given in Table 3.
                                  508

-------
                Table 3.  LAKE MICHIGAN WATER CHEMISTRY FOR
                      CONSERVATIVE AND TRACE ELEMENTS.
              Data on trace elements are from Rossmann (1973).

Element
Ca
Mg
Na
K
so4
Cl
Fe
Mn
Cu
Zn
Co
Ni
Mo
Ba
Concentration (mg/liter)
36
11
3.8
1.4
18
8.0
0.007
0.00084
0.0027
0.004
<0.001
0.0065
0.0018
0.026
                           MAJOR NUTRIENT CYCLES

Some data are available for the seasonal cycles of phosphorus, nitrogen
and silica in Lake Michigan—these elements and carbon are the major
nutrients for phytoplankton.  Supplies o£ carbon are more than adequate
for phytoplankton growth.

Phosphorus concentrations in the lake are low, with total phosphorus
averaging 8.0 yg P/liter (Table 2).  Allen (1973) reported averages of
less than 7.0 ug P for samples collected in 1965.  Soluble reactive
phosphorus being frequently below 1.5 yg P/liter leads one to question
                                  509

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the utility of this measurement, particularly on a routine basis
(Schelske and Callender 1970) .   No clear seasonal cycle of either soluble
reactive or total phosphorus is evident from Rousar (1973) or Allen
(1973) but summer values for total phosphorus appear to be smaller than
at other times of the year.

Of the three forms of combined inorganic nitrogen, only nitrate is
quantitatively significant.  Concentrations of ammonia and nitrite are
low being only a few percent  of the nitrate concentrations.  Nitrate
varies seasonally with a maximum in the winter of 0.27 mg N/liter
followed by a steady decline to 0.12 mg N/liter in August (Rousar 1973).
This decline is due to nitrogen utilization for phytoplankton growth.

The seasonal cycle for silica is similar to that for nitrate.  A maximum
value of 1.4-1.5 mg Si02/liter occurred for the winter of 1970-1971
(Rousar 1973).  Data from the Great Lakes Research Division, University
of Michigan, collected in the spring of 1971, agree well with these
values for the winter, and it seems reasonable therefore to conclude
that the maximum open-lake concentration was no greater than 1.5 mg/liter
(Stoermer 1972).  The minimum value reported by Rousar of 0.2 mg/liter
occurred in August.  Minimum values during the summer may not be accurate
due to technical problems associated with detecting concentrations lower
than 0.1 mg/liter, but it is clear from unpublished GLRD data that the
minimum is presently less than 0.1 mg/liter.

A more detailed discussion of the seasonal cycle of silica has been
derived from data collected in 1971 by the GLRD as part of a study of
algal quality in southern Lake Michigan (Stoermer 1972).  For this
discussion, silica depletion is defined as concentrations equal to or
less than 0.2 mg/liter.

Silica depletion in 1971 had occurred in localized nearshore areas at the
time of our first collections (in late March and early April).  Concen-
trations of 1.4 mg/liter were measured at mid-lake stations, indicating
little utilization by diatoms at this time, but were significantly less
than 1.4 mg/liter at distances as great as 6.4 km offshore.
                                  510

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The zone of silica depletion increased in May and June and by June
extended to at least 6.4 km offshore.  The mid-lake values ranged from
0.9 to 1.3 mg/liter in May and were generally less than 1.0 mg/liter in
June.  Silica concentrations in June over much of the lake were less than
0.7 mg/liter, indicating that half the silica reserve in the euphotic
zone had been utilized by diatoms.

Silica was essentially depleted in the euphotic zone to a depth of 20 m
in July.  In August and September concentrations remained low, generally
< 0.2 mg/liter over the study area.

Increases in silica in surface waters from the spring-summer lows were
not evident until the October cruise when concentrations ranged from 0.3
to 0.5 mg/liter.  Concentrations did not increase greatly on the next
and last cruise at the end of October, as most values ranged from 0.3 to
0.6 mg/liter.  Rousar did not find maximum values in the epilimnion until
January.
                               PHYTOPLANKTON

Based on the report of "more than 700 morphologically distinguishable
entities" in a study of plankton diatoms from Lake Michigan (Stoermer
and Yang 1969), one might conclude that the phytoplankton had been
studied extensively.  Such a conclusion would be erroneous for a number
of reasons recognized by Stoermer and Yang.  First, many of the data
analyzed were from nearshore regions that differ physically, chemically
and biologically from the open lake.  Second, there is a lack of season-
al data.  The only data collected seasonally are those obtained by
sampling municipal water intakes that are necessarily located close to
shore.  Third, many of the data were obtained from vertical plankton
tows, so the absolute abundance of organisms in the water cannot be
estimated.  Fourth, there are therefore few quantitative data on cell
counts or even on chlorophyll concentrations which might be used to
estimate the biomass of phytoplankton.  Stoermer and Yang therefore
                                  511

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studied the relative abundance of different organisms in available
collections.  With this approach, it was possible to obtain a comparative
data set for samples collected from as early as the 1880's to 1967 and to
make a detailed analysis of 44 common species (Table 4).  Because many of
the older samples were preserved as material for diatom identification or
in samples in which other types of algae were destroyed, it was not pos-
sible to work with the complete phytoplankton assemblage.

Historically, the plankton flora of Lake Michigan was dominated by
diatoms (Stoermer 1967; Ahlstrom 1936) as would be expected for a pris-
tine flora (Stoermer and Yang 1969) .  It is obvious from other studies
of the Laurentian Great Lakes, particularly Lake Superior which is the
most oligotrophic, that diatoms are the dominant phytoplankton organisms
(Holland 1965; Schelske et al. 1972).  It appears from limited studies
of populations in Lake Superior that the phytoplankton assemblage is the
typical Cyalote'ita plankton of oligotrophic lakes as characterized by
Hutchinson (1967).  The available collections from Lake Michigan indi-
cate that the oligotrophic Cyolotella plankton is presently never as
dominant as it is in Lake Superior (Holland 1969) .

The species composition of phytoplankton in Lake Michigan changed
markedly in the past 100 years as the result of accelerated eutrophica-
tion and possibly from other forms of pollution.  A change from 1930-
1931 to the 1960's was documented by Stoermer (1967).  During this time
interval, the number of euplanktonic species that could be considered
indicators of eutrophication increased 70 percent.  New species, such as
Stephanodiscus binderanus and Stephanodiscus hantzschii, characteristic
of eutrophic conditions became dominant (Stoermer and Yang 1970).  In
addition, more recently the predicted shift (Schelske and Stoermer 1971)
of phytoplankton assemblages dominated by diatoms to those dominated by
blue-green algae has occurred in summer populations (Stoermer 1972).

Seasonally the spring pulse  occurs as early as February and as late as
April at the Chicago water intakes, a nearshore location (W. F. Danforth,
111. Inst. Tech., personal communication), but based on chlorophyll it
                                   512

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               Table 4.  DOMINANT DIATOMS IN LAKE MICHIGAN.
                 As taken  from  Stoermer  and Yang (1970).
Amphipleura pellucida  (Kiitz.)
   Kutz.

Asterionella formosa Hass.

Cyolotella oomta (Ehr.) Kutz.

C. kuetzingiana Thwaites

C. meneghiniana var. plana
   Fricke

C. michiganiana Skv.

C. ooellata Pant.

C. operculata (Agardh) Kutz.

C. pseudostelligera Bust.

Diatoma tenue var. elongation
   Lyngb.

D. tenue var. pachycephala Grun.

Fragilaria capucina Desm.

F. ca.puci.na var. lanceolata Grun.

F. cccpucina var. mesolepta Rabh.

F. crotonens-is Kitton

F. intemed-ia Grun.

F. intermedia var. fallax (Grun.)

F. pinnata Ehr.

Melosira granulata (Ehr.) Ralfs

M. granulata var. angustissima
   0. Mull.

M. islandica 0. Mull.

Af. italica subsp. siibartioa 0. Mull.
Nitzsehia bacata Bust.

N. dissipata  (Kutz.)  Grun.

N. recta Hantz.

Nitzschia sp. #2.

Rhizosolenia eriensis H. L.  Smith

Stephanodiscus alpinus Hust.

S. binderanus (Kutz.) Krieger

S. hantzschii Grun.

S. minutus Grun.

S. niagarae Ehr.

S. subtilis  (Van Goor) A. Cleve

S. tenuis Hust.

S. trans-Llvon-icus Pant.

Synedra delicatissima var.
   angustissima Grun.

S. demerarae Grun.

S. filiforrrri-s Grun.

S. ostenfeldii (Krieger) A.  Cleve

S. ulna var. chaseana Thomas.

5. ulna var. danica  (Kutz.)  V.H.

Tabellari-a fenestrata (Lyngb.)
   Kutz.

T. fenestrata var. geniculata
   A. Cleve

T. flocculosa (Roth) Kutz.
                                    513

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does not occur until May or June in the offshore waters between Milwaukee
and Ludington (Rousar 1973).  One would expect the pulse to be delayed
from south to north due to cooler air temperatures and from the shore to
open lake due to slower increases in offshore water temperature.  These
effects are related to the length of the lake and the thermal bar.  The
latter effect is evident in the data presented by Ladewski and Stoermer
(1973) and by Stoermer (1972).  The summer minimum occurs in late August
and September followed by an autumnal pulse smaller than the spring
maximum.  According to Rousar's data, chlorophyll a concentrations for
the open lake average 4.5 mg/m^ during the spring pulse, 3.0 mg/m^ for
the fall pulse and about 1.0 mg/nr during the summer minimum.  Ladewski
and Stoermer (1973) found a spring maximum of 2.7 mg/m^, a fall maximum
of 1.8 rng/m^ and a summer minimum of 0.7 mg/nr* from data averaged for 13
offshore stations (Fig. 4).  Allen (1973) reported a minimum of 0.5 mg/m^
and a maximum of 2.4 mg/m^.

In terms of species composition the spring pulse is dominated by diatoms
and the summer minimum by blue-greens (Stoermer 1972).  Blue-greens in
surface samples in 1971 comprised a major fraction of the phytoplankton
counts from late August until late October when sampling was terminated
(Stoermer 1972); percentages of blue-greens exceeded 80% in many of the
samples.  The dominant species was Anacystis ineevta.

The spring pulse from 1968-1972 at Chicago was dominated by S.
bindeTonus and S. hantzsahiij while the autumn maximum consisted mainly
of Astepionetla, Fragila^ia3 and TabeZtcon-a (Danforth, personal communi-
cation) .  S. hantzschii and S. bindspanus were not common at the Chicago
filtration plants until 1956 and 1960, respectively— these species
apparently replaced Melosira islandioa indicating severe environmental
perturbation (Stoermer and Yang 1970), presumably nutrient enrichment.
Holland (1968, 1969) found that M. islandioa was dominant in the open
waters during May and June, but was replaced by other species of Metosiva
in more eutrophic areas; one of the species of Melosira, M. bindevana is
a synonym for S. binderanus.  Fluctuations in the standing crops of

                                   514

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     12
CO
 0>
  E
 O
 u
 >•
 2
 X
 U
      8
             May      July      Sept
Nov
  Figure 4.  Chlorophyll concentration in 1971 averaged

  by depth range and month.  See Figure 3 for key.

  (From Ladewski and Stoermer 1973.)
                           515

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common diatoms from May to October in northern Lake Michigan have been
studied by Holland (1969).

The relative abundance of Chlorophyta, Chrysophyta, and Cyanophyta in
the offshore plankton was studied by Stoermer (1967) .  Each group
comprised only a minor part of the phytoplankton compared to the
Bacillariophyta.  Some of the more abundant forms of green algae were
Botryooooous brawLi Kutz., Closterium aeLaulape West, Diotyosphaerium
pulohellum Wood, Sphaevooystis sdhroeteiri, Chodat, and several species of
Oooystis Nageli.  The main genus of Chrysophyta was Dinobryon Ehr..
Five species were recorded, but the dominant one was D. divevgens Imhof.
Blue-greens were represented by Chvoooooaus lirmeticus Lemm., C. minutus
(Kutz.) Nageli, Coelosphaeriwn naege'i'ianum Unger, Gomphosphaeria
laeustris Chodat, and Oseillatom-a mougeotia Kutz.

Phytoplankton productivity is relatively low with summer values averaging
about 4.0 mg C/m^/hr (Schelske and Callender 1970).  Annual rates of
carbon fixation for offshore waters ranged from 121-139  g C/m^ at three
offshore stations between Ludington and Milwaukee as compared to a
maximum value of 247  g C/m^ at a nearshore station near Milwaukee (Fee
1973).  Phytoplankton productivity in the Great Lakes has been compared
by Vollenweider et al. (1974).
                                ZOOPLANKTON

Studies of zooplankton have concentrated mainly on the Crustacea
(Table 5) with very little being known about Protozoa or Rotifers
including their taxonomy (Gannon 1972a).  There are no data on open-
water zooplankton prior to 1954 (Wells 1970) or for the winter months.
Zooplankton studies on the Great Lakes have been reviewed by Watson
(1974).

Wells (1970) found changes between 1954 and 1966 in both the size and
species composition of zooplankton populations.  Size-selective preda-
                                  516

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             Table 5.  ZOOPLANKTON CRUSTACEA OF LAKE MICHIGAN.

Common Gannon
Species (1972a)
Copepods
Diaptomus ashlandi Marsh
Diaptomus minutus Lilljeborg
Diaptomus oregonensis Lilljeborg
Diaptomus sicilis Forbes
Episehura laoustris Forbes
Eurytemora affinis (Poppe)
Limnooalanus maorurus Sars
Seneoella calanoides Juday
Cyclops biouspidatus thomasi Glaus
Cyclops vemalis Fischer
Eucyclops agilis (Koch)
Mesocyclops edax (Forbes)
Tropocyolops prasinus mexicanus Kiefer
Canthooamptus robertookeri M.S. Wilson
Cladocera
Bosmina longirostris (Muller)
Eubosmina coregoni Baird
Daphnia galeata-mendotae Birge
Daphnia longiremis Sars
Daphnia retpocuwa Forbes
Daphnia schtfdleri Sars
Ceriodaphnia lacustris Birge
Ceriodaphnia quadrangula (Muller)
Alona affinis (Ley dig)
Chydorus sphaericus (Muller)
Holopedium gibberum Zaddach
Leptodora kindtii (Focke)
Polyphemus pedioulus (L.)
Diaphanosoma leuehteribergianum Fischer

X
X
X
X
X
X
X
X
X
X

X
X
X

X
X
X
X
X
X
X
X
X
X
X
X
X
X
Wells
(1970)

X
X
X
X
X
X
X
X
X
X

X



X
X
X
X
X

a
a


X
X
X
X
Roth and
Stewart
(1973)

X
X
X
X
X
X
X

X
X


X
X

X
X
X

X


X

X
X
X
X
X
Ceriodaphnia species.
                                  517

-------
tion by alewife was given as the most likely factor for the change.
The largest species, Leptodora kindtii   Daphnia galeata-mendotae3 D.
vetroourva., Limnooalanus maerurus, Epischura laaustvis, Diaptomus
sieilis and  Mesocyalops edax, declined in abundance with D. galeata-
mendotae and M. edax decreasing from abundant to extremely rare.  At the
same time smaller species increased in abundance.  Species such as M.
edax3 D. galeata-mendotae, Diaptomus oregonensis, Diaphanosoma
leuchtenbergianum and L. kindtii that decreased in Lake Michigan due to
selective predation are abundant in Green Bay.  Gannon (1972b) concluded
that size-selective predation had a smaller effect on zooplankton
Crustacea in Green Bay than in open Lake Michigan because higher rates
of primary productivity support greater rates of zooplankton production
in Green Bay.  If greater primary productivity is a causal factor it
would be related directly to eutrophication.

Eurytemora, a marine species, has invaded the lake— it was recorded by
Wells (1970) in 1966 but not in 1954 and by other workers (Table 5).

Seasonal distribution of the major groups appears quite simple.  Copepods
are present throughout the year, but cladocerans are found only during
the summer.  Gannon's data indicate that cladocerans do not appear until
thermal stratification is present and persist until the lake becomes
homothermous.  Cyclops biauspidatus thomasi is the most abundant copepod
with Diaptomus ashlandi, Diaptomus minutus, Diaptomus oregonensis,
Diaptomus sieilis and Limnooalanus maaruvus being common but less
abundant.  Cladocera are most abundant from June to September with the
maximum populations occurring in July and August when copepods are also
most abudant.  In the summer the dominant species are the copepods, C.
bicuspidatus thomasi, Diaptomus ashlandi and the cladocerans, Bosmina
longirostris, Daphnia petrocurvaj and Daphnia galeata-mendotae.  Bosmina
dominates the zooplankton in July and August.  Later in the summer during
August and September Daphnia replaces Bosmina as the dominant cladoceran.

Quantitative data on zooplankton abundance are lacking, with only four
studies of major importance.  Each of these studies was restricted to
                                  518

-------
small areas of the lake or to few stations.  In addition, the data are
not comparable as two different methods were used.  Wells (1970) used
horizontal tows with a calibrated Clarke-Bumpus sampler and 0.366 mm
silk net; Gannon (1972a), Roth and Stewart (1973), and Stewart  (1974)
used vertical tows with a 0.5-m diameter nylon net.  Gannon used a
0.256-mm aperture and Roth and Stewart used a 0.158-mm aperture.  All of
the data are reported as individuals/m.  Gannon's station was  60 m deep
and Roth and Stewart's stations were 14 m for the nearshore station and
40 m for the offshore station.  Gannon reported a maximum crop  of 8300
individuals/m3 in August, whereas Roth and Stewart (1973) reported
maxima of 130,000 individuals/m^ in July at the offshore station and
280,000 individuals/m^ at the nearshore station in August.  Roth and
Stewart considered that some of these differences may have been due to
more immature forms being collected by their smaller mesh net, but
concluded that the main factor was greater productivity in their study
area.

Roth and Stewart (1973) also noted differences between their offshore
and inshore station.  The cladoceran bloom appeared to start earlier at
the nearshore station and contained a greater proportion of cladocerans
than the offshore station, presumably an effect attributable to earlier
warming at the inshore station.  The large population of Bosmina
longirostris at the nearshore station was attributed in part to size-
selective feeding by abundant nearshore fish on zooplankton.  Whether
the inshore station contained larger standing crops of zooplankton is a
question of data interpretation, since the offshore station was three
times deeper than the nearshore station.  Maximum standing crops on an
areal basis therefore would have occurred at the offshore station,
because abundances at the nearshore station were seldom greater than a
factor of two larger than the offshore station.  Actually the largest
standing crop of zooplankton, 360 mg dry weight/m^, occurred at the
offshore station in July; the largest standing crop at the nearshore
station was 280 mg dry weight/m^ in August.  Biomass values were as low
as 30 mg dry weight/m3 in April.

                                   519

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                                  BENTHOS

Knowledge of the benthos is restricted mainly to the macroinvertebrates.
Numerically the fauna in the main lake is dominated by Amphipoda,
Oligochaeta, Sphaeriidae, and Chironomidae in that order (Robertson and
Alley 1966).  Nearshore Gastropoda, Hirudinea, other Insecta and other
Crustacea may be numerous (Mozley 1974).  In the main lake, Pontoporeia
affinis is the only species of Amphipoda.  Cook and Johnson (1974) have
reviewed several aspects of studies on macrobenthos of the Great Lakes.

Powers and Alley (1967) investigated the depth distribution of benthos.
Maximum numbers occurred at 30 m, with large numbers being present at 40
and 50 m.  At depths of 20 m and greater, Pontopore-ia was the dominant
organism, comprising more than 50 percent of the total counts.  Propor-
tions of Pontoporeia increased with depth, with 75 percent of the total
being at depths greater than 80 m.  At 30 m, the mean and standard
deviation of total counts/m^ was 15,000 + 6,700 and at 40 and 50 m it was
11,000 + 5,000.  At 30, 40 and 50 m, the mean and standard deviation for
Pontoporeia was 8,600 + 3,700, 6,800 + 3,100 and 6,300 + 2,800.  The mean
number of benthic organisms declined to less than 1,000 at depths greater
than 200 m.  Average standing crops (dry weight) of macrobenthos ranged
from highs of 10 and 20 g/m^ at 30 and 10 m to approximately 0.3 g/m2 at
depths greater than 200 m.

At depths less than 30 m, the second most abundant group of organisms is
the Tubificidae (Mozley 1974).  This group of oligochaetes, composed of a
number of species, is dominated by LimnodvUus hoffmeisteri, Potcmothi*ix
moldaviensis, Pelosoolex freyi, P. ferox and Tubifex tubifex.  In
addition, the lumbriculid oligochaete Stylodrilus heringianus is abundant
at depths greater than 20 m (Hiltunen 1967).

Sphaerids are most abundant at 30 m and also occurred abundantly at
depths of 60 m and less.  There are three species of SphaeTium, S.
nitidwn, S. stviati-num, and S. oomeum, and at least nine species of
         (Robertson 1967).  The deep water species, P. oonventus, is the
                                    520

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most abundant Pisiditffn.   In shallow water, P. ca.ser~ta.nwn, P. henslowanum
and P.  lill-jebofgi are the most abundant species.

Chironomids form a relatively minor part of the benthos,  with maximum
counts averaging 200/m2  at 40 and 50 m (Powers and Alley  1967) .   This
group is complex from the taxonomic standpoint, so species identification
is either not attempted  or is questionable in many studies.   Certain
species have been considered pollution tolerant and others as pollution
intolerant, thereby types of chironomids have been used to assess
environmental quality (Brinkhurst, Hamilton and Herrington 1968;  Mozley,
In prep.).

The benthic fauna in deep waters has been affected little by environmental
changes.  Although abundances of Pontoporeia and oligochaetes were signifi-
cantly greater in 1964 than in 1931, Robertson and Alley  (1966)  stated "no
definite conclusions can be reached concerning long-term trends" due to
expected year-to-year variations in abundances.  Severe changes in benthic
organisms have occurred  in localized areas, harbors, bays, and river mouths,
but extensive changes over large areas have been observed only in southern
Green Bay (Howmiller and Beeton 1970).  In southern Green Bay, drastic
changes have been documented, including the disappearance of mayfly nymphs
(Hexagenia), a change that also occurred in the western basin of Lake Erie
as the result of oxygen depletion (Britt 1955).
                                    FISH
Much has been written about the fish fauna, partly reflecting the concern
over decreases in the abundance of species in the commercial fishery.
Wells and McLain (1973) summarized many of the papers dealing with the
history of fish and list 38 species (Table 6) as "all common fish of
Lake Michigan, past and present."  A much longer list of species,
numbering 70 to 75, resulted from intensive sampling of species that "are
extremely rare or transients that normally inhabit streams, inland lakes
or protected bays" (Jude et al. 1975).  Only 32 of these 70 species were
                                   521

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 Table 6.   PAST AND PRESENT  COMMON FISH OF LAKE MICHIGAN.
 Sea lamprey3
 Lake sturgeon
 Alewifea
 Lake whitefish
 Blackfin cisco
 Deepwater Cisco
 Longjaw cisco
 Shortjaw cisco
 Bloater
 Kiyi
 Shortnose cisco
 Lake herring
 Round whitefish
 Lake trout
 Brook trout
 Rainbow trout  (steelhead)a
 Brown trout a
 Coho salmona
 Chinook salmon3
 Rainbow smelt3
 Northern pike
 Carpa
 Emerald shiner
 Spottail shiner
 Longnose sucker
 White sucker
 Channel catfish
 Bullheads
 Trout-perch
 Burbot
 Ninespine stickleback
 Smallmouth bass
 Yellow perch
 Walleye
 Freshwater drum
 Slimy sculpin
 Spoonhead sculpin
 Fourhorn sculpin
Petromyzon mar-inus
Aaipenser fulvescens
Alosa pseudoharengus
Coregonus oZupeaformis
Coregonus nigripinnis
Coregonus johannae
Coregonus alpenae
Coregonus zenifkicus
Coregonus hoyi-
Coregonus kiyi
Coregonus reighardi
Coregonus artedH
Prosopium cylindraceurn
Salvelinus namayaush
Salvelinus fontinalis
Salmo gairdneri,
Salmo trutta
Oncorhynahus kisutch
Oncorhynchus tshauytscha
Osmerus mordax
Esox luaius
Cyprinus carpio
Notropis atherinoides
Notropis hudsonius
Catostomus aatostomus
Catostomus aommersoni,
Ictalurus punctatus
letalurus  spp.
Percops-is omi,scomaycus
Lota Iota
Pungitius pungitius
Micropterus dolomieui.
Peraa flavesaens
Stizostedion witreum witrewn
Aplodinotus grunniens
Cottus aognatus
Cottus r-Lcei,
Myoxocephalus quadri-aornis
a Species  that  have  been introduced  or  invaded the lake.
                             522

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collected in both years of the two-year study of a nearshore area in the
southeastern part of the lake.

During the period of historical record, eight common species were either
introduced or gained access to the lake (Table 6).  The rainbow trout or
steelhead, brown trout and carp have been present in Lake Michigan since
the turn of the century.  A few chinook salmon were introduced between
1873 and 1880 but they did not become established.  Extensive stocking of
coho salmon and chinook salmon began in 1966 and 1967.  It was originally
thought that these species would not reproduce in the Great Lakes and,
although there is ample evidence that spawning runs have been established
in streams in Wisconsin and Michigan, it is still not certain if these
spawning runs would continue if stocking was discontinued.  Another salmon
from the Pacific Ocean was introduced with the release of 2,000 masu
salmon (OncoThynohus masou) in 1920, and some 645,000 Atlantic salmon
(Salmo solar) were released in the lake between 1872 and 1932, but
neither became established.  The pink salmon (Oncorhynchus gorbuseha) is
the only introduced salmon that has established self-sustaining popula-
tions.  It was introduced in Thunder Bay, Lake Superior in 1956 and has
recently spread to Lakes Huron and Michigan.

Three of the species presently common in the lake are native to the
Atlantic Ocean.  First records of the rainbow smelt in 1923, the sea
lamprey in 1936 and the alewife in 1949 represent relatively recent
introductions.  The smelt in Lake Michigan originated from a planting in
Crystal Lake, Michigan in 1912 (Van Oosten 1937).  The alewife and sea
lamprey probably entered the Great Lakes drainage via the Erie Canal
which linked the Mohawk-Hudson River system entering the Atlantic Ocean
with the Oneida-Oswego River system entering Lake Ontario (Smith 1970;
Aron and Smith 1971) .  They became established in Lake Ontario and
subsequently circumvented the natural barrier at Niagara Falls and reached
the other Great Lakes via the Welland Canal.

Some of the introduced species have caused severe environmental problems
as well as (at least on the short term) environmental benefits.  Most
                                   523

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experts on the problems of the commercial fisheries of the Great Lakes
attribute some of the cause to the invasion by the sea lamprey.  In Lake
Michigan, during its period of maximum abundance in the 1950's, the sea
lampreys destroyed from five to twelve million pounds of fish per year.
At this time the prey was largely deepwater ciscoes, as most of the lake
trout had disappeared (Smith 1968).  Control measures for sea lamprey
have been successful.  Adult fish are trapped in weirs on the spawning
streams,and the larvae are killed in the spawning streams with the
selective larvicide, 3-trifluoromethyl-4-nitrophenol.

With the decline in lake trout and other large predators, the population
explosion of alewives resulted, reaching a climax in 1967 with massive
dieoffs of alewives.  Dead fish clogged municipal and industrial water
intakes and littered beaches, detracting from their desirability for
swimming and creating costly problems of removal.  Coho salmon and
chinook salmon from the Pacific Ocean have been introduced since 1966 and
1967, partly to overcome the problem of over-population with alewives,
providing a predator to check population increases and large fish for a
sport fishery.  Results were dramatic, the salmon flourished on the abundant
alewives and provided an excellent sport fishery.  In Lake Michigan the
largest fish caught by angling have been a 13.7 kg coho, only  .4 kg less
than the world's record, and a 19.6 kg chinook.

Although largely successful, stocking Pacific salmon has not been with-
out its environmental repercussions.  When salmon mature they return to
spawn in the stream in which they were stocked.  These spawning runs of
salmon have been extensive, creating a bonanza for fishermen in the
streams.  They also provide large numbers of fish that can be removed by
unsportsmanlike  means including snagging.  Dead fish often litter the
streams as they die after spawning or are caught and discarded by fisher-
men who do not value fish in poor spawning condition.

Historically and continuing to the present time, the most common native
and introduced fish, especially the large predators, are species
characteristic of oligotrophic environments.  This fact alone leads one
                                  524

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to conclude that some of the characteristics of open Lake Michigan are
definitely oligotrophic.  The original fish fauna included 10 species of
coregonids (Table 6) and one salmonid.  Of these the lake whitefish, lake
herring and lake trout were taken in the largest quantities by the
fishery.  Whitefish are recovering as a result of sea lamprey control,
and lake trout are being maintained through artificial stocking, but the
other species are no longer abundant.  All of these species have been
sought actively by commercial fishermen and have been significant in the
commercial fishery.

Commercial fishing in Lake Michigan began at least as early as 1843
primarily for abundant nearshore populations of lake whitefish.  "By 1860
certain grounds for this species were becoming depleted and by the 1870's
complaints about the scarcity of whitefish were common" (Wells and McLain
1973).  Logging and dumping sawdust in streams were factors in the
decline.  Other species were abundant in the fishery and then declined.
For example, catches of lake trout averaged eight million pounds in the
early 1900?s, declined to five million pounds in the 1930's and increased
to more than six million pounds in the early 1940's before declining
sharply in the late 1940's.  By the mid-1950's, the lake trout was
believed to be extinct.

The total commercial production was greatest from 1893-1908 when the
average harvest was 41 million pounds yearly.  Production dropped between
1908 and 1911, due primarily to a decrease in catches of lake herring,
and then fluctuated with catches ranging from 20 to 30 million pounds
until 1966 when catches of alewives became large.  The peak year was 1967
when the total catch was 60 million pounds, of which 42 million pounds
were alewives.

Causes for changes in the fish fauna are not fully explained (Smith 1972).
Some of the factors have been modification of the drainage basin first by
logging and then by agriculture, influences of urbanization and industri-
alization, invasion of the sea lamprey, and undoubtedly the effects of
overfishlng for commercial species (Smith 1972).
                                   525

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                        ASSESSMENT OF TROPHIC CHANGE

Basically either chemical or biological approaches can be used to deter-
mine changes in the trophic status of lakes.  Detectable changes in the
biota should be those that result from nutrient enrichment of the system
or in the case of Lake Michigan from increased loading of phosphorus.

Of the biota only the phytoplankton can be used to determine changes in
trophic state of Lake Michigan.  Qualitatively, the benthic community has
been affected little by nutrient enrichment, and quantitatively the
problems of large variances in sampling invoke the need for large differ-
ences to detect changes in standing crops (Mozley 1974).  No zooplankton
data are available for long-term assessments of standing crop and there
is no direct evidence that changes can be used to assess trophic changes—
the latter aspect also is confused by size-selective predation by fish
and its resultant shifts in species composition.  Many changes in the
abundance and species composition of fish have been documented, but these
"have been largely unexplained and have been a subject of uncertainty and
controversy" (Smith 1972).  One of the reasons that changes in trophic
state have not been obvious is that the biological communities of the
open waters, with the exception of the phytoplankton, continue to be
those characteristic of oligotrophic environments.

Changes in the phytoplankton species composition have been documented,
and the cause for the change has been related to increased inputs of phos-
phorus.  Changes in species composition have occurred that apparently
reflect nutrient enrichment.  Changes in the diatom flora have been
documented in papers by Stoermer and Stoermer and Yang from data
collected in the early 1960's.  Another shift in species composition has
occurred due to depletion of silica in the euphotic zone during the
summer—this shift is the replacement of diatoms by blue-green algae as
the phytoplankton dominant.  These blue-greens, however, are not Anabaena
flos-aquae or Mieroeystis, the most common nuisance forms, and the
standing crops are not large due to the relatively low levels of phos-
phorus in the system.
                                   526

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It is possible that much of this change is relatively recent, perhaps
the most serious changes have occurred in the last 20 years.  Nuisance
species of Stephana discus, S. ln.antzsohii and S.  binderanus, did not
appear in the phytoplankton at the Chicago water intake prior to 1956.
In the mid-1950's (Ayers et al. 1958) and in the early 1960's (Risley
and Fuller 1965), reported levels of silica during the summer that would
not limit diatom growth.  But by 1969, levels over the entire lake basin
were no greater than 0.2 mg SiC>2/liter in the epilimnetic waters
(Schelske and Callender 1970).  Further evidence for a relatively recent
effect caused by increased inputs of phosphorus comes from recent
mathematical modelling of phytoplankton growth in Lake Ontario (Thomann
et al. 1975).  This model indicates that three detention times or 24
years are needed to reach a steady state.  In Lake Michigan it would be
more appropriate to use three residence times for phosphorus or approx-
imately 18 years as the time needed to reach equilibrium.  The model
suggests that effects of increased phosphorus loading will not be
manifested in the lake immediately and would have been delayed from the
first large increases in loading, probably in the 1940's.

If there is a significant delay between the time of phosphorus inputs
and the effects produced in the biological system, then one can accept
the hypothesis that major changes in the open-water phytoplankton have
occurred in the past 20 years.  If this is true it may also be one of the
reasons why there has not been a measurable effect in the benthos and
other components of the biological system.

Assessing differences or changes in trophic state of oligotrophic waters
from biomass of phytoplankton or concentrations of chlorophyll a may not
be practical as relatively large differences or intensive sampling may be
required.  It is not certain that a statistically significant increase of
0.5 mg/m^ in the spring maximum of chlorophyll a could be detected on a
lakewide basis as  this would represent an increase of 20 percent.  It
seems obvious more sensitive techniques are needed.  One technique that
offers increased sensitivity is the use of environmental parameters that
integrate environmental processes.  Hypolimnetic oxygen depletion has
                                   527

-------
been used for this purpose in shallower lakes, but there is little change
in hypolimnetic oxygen concentrations in Lake Michigan.   Schelske (1975)
proposed that silica and nitrate depletion in the euphotic zone during
summer stratification could be used to assess trophic state.

Chemical changes or utilization of nitrate and silica in the upper Great
Lakes are related to trophic state in the upper Great Lakes.  Reserves of
these nutrients in surface waters (photic zone) are depleted by phyto-
plankton during summer stratification.  Reserves, as indicated by
differences in concentrations between bottom and surface waters, are
related inversely to trophic state:  Lake Superior, the most oligotrophic,
has the greatest reserves, and Lake Michigan, the most eutrophic, has the
smallest reserves (Fig. 5).

In conclusion, one would expect eutrophication of Lake Michigan to be a
function of increasing phosphorus concentrations.  Unfortunately adequate
data are not available for consideration.  The rate of silica depletion
may be the most sensitive means of assessing changes in trophic state
since the dominant phytoplankton are diatoms.  Diatoms require silica
for growth, so as nutrient enrichment increases standing crops of diatoms
utilize silica in increasing amounts and rates.  Even though silica is
depleted in the summer, rates or annual quantities of silica utilized by
diatoms can still be used to assess trophic state.  Rates of depletion
would have to be calculated for the spring bloom period.  Finally, if
eutrophication of Lake Michigan continues, the total amount of silica in
the lake would continue to decline.  Conversely, if eutrophication is
reversed, the total amount of silica in the lake should remain constant
or increase.

Contribution No. 192 of the Great Lakes Research Division, The University
of Michigan.
                                  528

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                                  536

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