EPA-660/3-73-001
July 1973                          Ecological  Research Series
 WEED  HARVEST  AND LAKE
 NUTRIENT  DYNAMICS
                                     Office of Research and Development

                                     U.S. Environmental Protection Agency
                                     Washington, D.C. 20460

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            RESEARCH REPORTING SERIES
Research reports of the   Office  of  Research  and
Monitoring,  Environmental  Protection Agency, have
been grouped into  five series.   These  five  broad
categories  were established to facilitate further
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technology.   Elimination  of traditional grouping
was  consciously   planned  to  foster   technology
transfer   and  a  maximum   interface  in  related
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   1.  Environmental  Health Effects Research
   2.  Environmental  Protection Technology
   3.  Ecological  Research
   4.  Environmental  Monitoring
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This report has been  assigned  to  the  ECOLOGICAL
RESEARCH  series.   This  series describes research
on the effects of  pollution on humans,  plant  and
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assessed   for   their    long-   and    short-term
influences.    Investigations  include  formation,
transport, and pathway studies  to  determine  the
fate  of  pollutants  and  their effects.  This work
provides the technical basis for setting standards
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organisms   in   the   aquatic,   terrestrial  and
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For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $1.26

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                                               EPA-660/3-73-001
                                               July  1973
      WEED HARVEST AND LAKE JJUTRIENT DYNAMICS


                         by
                    Joe K. Neel

                Spencer A. Peterson

                 Wintfred L.  Smith

               Department of  Biology
             University of North Dakota
          Grand Forks, North  Dakota  58201
               Project No. 16010 DFI
                   Project Officer
               Dr. Charles F. Powers
Pacific Northwest Environmental Research Laboratory
              Corvallis, Oregon  97330
                    Prepared for
         OFFICE OF RESEARCH AND MONITORING
        U.S. ENVIRONMENTAL PROTECTION AGENCY
              WASHINGTON, D.C.  20460

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                   EPA Review Notice
This report has been reviewed by the Environmental
Protection Agency and approved for publication.
Approval does not signify that the contents necessarily
reflect the views and policies of the Environmental
Protection Agency, nor does mention of trade names or
commercial products constitute endorsement or recommenda-
tion for use.
                           11

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                            ABSTRACT

     After more than 60 years of cultural eutrophication Lake Sallie
supports dense growths of phytoplankton and rooted vegetation.  Its
major water mass has the chemical character imparted by photosynthesis
at all seasons, and chemical effects of decomposition are rather
localized.  Phytoplankton dominance alternates among diatoms, blue-
green, and green algae, in that order of abundance.  Prior to operation
of a weed harvester, attached plants grew densely over 34% of the
bottom area.  The bulk of nitrogen and phosphorus is usually contained
in the water mass, with noticeably smaller amounts in upper bottom
sediments and biota.  The fish population, less than one half the mass
of weeds, contained considerable more N and P than weeds in 1971.
Harvest in 1970 evidently reduced weed density in 1971, and increased
the cost per unit of nutrients removed.  Nitrogen and phosphorus
removed in weeds were insignificant when compared with annual waste-
water effluent contributions to the lake.  Cost of phosphorus removal
by weed harvest was $61 and $199 per pound in 1970 and '71, respect-
ively; nitrogen cost $8 and $21 and carbon $0.64 and $1.62 per pound
for the same two years.

     This report was submitted in fulfillment of Project Number
16010 DFI under the sponsorship of the Water Quality Office, Environ-
mental Protection Agency.
                                 111

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                            CONTENTS
SECTION




    I




   II




  III




   IV




    V




   VI
  VII




 VIII




   IX




    X




   XI
Conclusions




Recommendations




Introduction




Study Area




Materials and Methods




Discussion




     Climatological Features




     Physical Features




     Chemical Features




     Biological Features




     Water and Nutrient Budgets




     Effects of Weed Harvest




Acknowle dgmen t s




References




Figures




Tables




Appendices
PAGE




  1




  2




  3




  4




  7




 10




 10




 10




 11




 18




 25




 26




 27




 28




 30




 60




 82
                                v

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                            FIGURES


No.                                                           Pag6

 1     Bathymetric map of Lake Sallie Minnesota                 31

 2     Flow Route of Wastewater Effluent from Detroit           32
       Lakes to Lake Sallie

 3     Glacial Deposits in the Pelican River Watershed          33

 4     Lake Sallie Sampling Stations                            34

 5     Transects for Towing Oxygen Probe                        35

 6     Weed Harvest Areas in Lake Sallie                        36

 7     Temperature Variation at Surface and 10 Meters           37

 8     Temperature Variation with Depth, 1971                   38

 9     Position and Thickness of Thermocline 1971, in           39
       Lake Sallie

10     Annual Variation in Light Intensity at 1 and 3m         40

11     Seasonal Changes in Wave Length Penetration     41, 42,  43

12     Distribution of Sand in Lake Sallie Sediments            44

13     Variation in Surface Water pH at 3 Lake Sallie Sites     45

14     BOD Variation at 3 Lake Sallie Stations                  46

15     Mean Monthly Percentages of Major Phytoplankton          47
       Groups in Surface Water, Station 4

16     Variation in Limnetic Phytoplankton Concentration   48,  49
       with Depth

17     Variation in Concentration of Major Plankton Groups      50
       in Surface Water

18     Seasonal Succession in Concentration of Major Phyto-     51
       plankton Groups in Surface Water at Station 41

19     Areas with Rooted Vegetation                             52

20     Gross Primary Production in Limnetic Surface Water       53
       (Station 4)

                                vi

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21     Average Gross Primary Production in the Limnetic         54
       Photic Zone

22     Net Primary Production and Respiration Rates in          55
       Surface Water at Station 4

23     Net Primary Production and Respiration Rates within      56
       the Photic Zone at Station 4

24     Vertical Variation in Gross Primary Production on        57
       Selected Dates at Station 4

25     Variation in Incident Solar Radiation  (Langleys)         58
       and Hourly Change in Primary Production Rate at
       Station 4, June 24, 1971

26     Photosynthetic Efficiency at Station 4 During 1971       59
                                 vn

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                             TABLES

No.                                                               Page

 1     Mean Temperature and Precipitation Recorded at              61
       Detroit Lakes, Minnesota

 2     Vertical Variation in Water Chemistry at Station 4,     62, 63
       Lake Sallie, Minnesota                              64, 65, 66
                                                           67, 68, 69
                                                           70, 71

 3     Nitrogen, carbon,  and phosphorus concentration in       72, 73
       sediments collected from shallow and deep water
       areas of Lake Sallie, Minnesota

 4     Acid-Soluble phosphorus of air dried sediments              74
       from Lake Sallie

 5     Total Kjeldahl nitrogen of sediments, Lake Sallie,          75
       Minnesota

 6     Concentration of certain elements in various aquatic    76, 77
       plants, Lake Sallie,  Minnesota, September 16., 1968

 7     Chemical analyses  of aquatic macrophytes from certain       78
       areas in Lake Sallie

 8     Primary productivity of submerged vascular plants and   79. 80
       associated plankton

 9     Water and nitrogen and phosphorus budgets in Lake           81
       Sallie 1968-69 to  1970-71
                              Vlll

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                    FINDINGS AND CONCLUSIONS

1.  Cultural enrichment of Lake Sallie has produced a highly photo-
synthetic lake rich in phytoplankton and attached vegetation.

2.  The chemical character of the major water mass is normally that
imparted by photosynthesis, since the rate of decomposition has been
too low to alter upper waters greatly even under ice and snow.

3.  Phytoplankton is not dominated by any major group, but its com-
position usually varies with season with one of four groups predomin-
ating.  Greatest densities (55,000,000+ per 1) have been achieved by
diatoms; blue-green algae have attained more than 6,000,000 units per
1.  Other ranking groups (green algae and Cryptophyceae) have been
much less numerous.

4.  The major nutrient source is the Pelican River which receives the
waste water effluents from Detroit Lakes.  A progressive downlake
decrease in nutrients is usually evident between the inlet and outlet
of this river, but some variation has occurred.

5.  The bulk of nitrogen and phosphorus is usually contained in the
water mass  (quantities for weeds the exceptional year are based on
approximations) with considerably lesser amounts in upper sediment
layers and bodies of organisms.  The fish population, although less
in mass, has had more contained nutrients than the rooted plant
assemblage.

6.  After one year's harvest, density of weeds was about 1/4 as great
the following year and phytoplankton density and photosynthesis
increased.

7.  Weed removal plus the annual controlled fish harvest took out insig-
nificant amounts of nitrogen and phosphorus with respect to amounts
brought in annually by the Pelican River.

8.  Cost of nutrient removal by weed harvest increased with declining
weed density, e.g., phosphorus from $16 and $199 per pound from 1970
to 1971.

9.  Weed harvest can exert little control on phytoplankton unless it
removes more nutrients than are annually contributed from outside
sources, and may actually expedite phytoplankton development if this
condition is not met.

10. Since most nitrogen and phosphorus usually occur in the water mass
they could be expected to decline soon following significant reduction
of nutrients in wastewater entering the Pelican River.

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                        RECOMMENDATIONS

1.  In view of its cost and inefficiency, weed harvest is not recom-
mended as a method for lowering nutrient supplies in a lake receiving
cultural enrichment.  Unless it can remove more than a year's incre-
ment of nutrients from outside sources, it will be inconsequential or
even detrimental to alleviation of undesirable phytoplankton growth.
It could be applied to hasten recovery of an eutrophied lake whose
nutrient source has been significantly curtailed, but annual outside
contributions would have to be low and many weeds in harvestable
situations.

2.  Harvesting evidently interferes with weed growth and renewal, and
operation during a second year may be expected to remove much fewer
weeds; thus a few years may need :elapse before the method may be
economically reapplied to an originally justifiable situation, i.e.,
where it could remove more than 1 year's nutrient increment.  Justi-
fication may be determined from annual nutrient load entering the
lake, standing harvestable weed crop, and weed nutrient concentration.

3.  In order to reach most weeds it would be desirable to have harvest-
ers capable of operating in 2 feet of water.

4.  Removal of weeds and fish may hasten "de-eutrophication" after
elimination of nutrient inflow, but the latter appears to be a
mandatory first step for any real success.

5.  Where the presence of weeds poses problems, cutting and removal
can apparently bring about improvement for at least one growing  season
following the harvest year.

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                          INTRODUCTION

     Eutrophication is a term somewhat loosely applied today to both
natural aging of lakes and nutrient and organic matter enrichment of
all water bodies.  Enrichment is frequently augmented by man, which
has led to coinage of the term, "cultural eutrophication", and
evidence has been presented that suggests it began in the Bronze Age
in Europe  (Easier, 1947).  Zurichsee in Switzerland exhibited gradual
increases in phosphorus, nitrogen, and chloride from 1888 to 1916,
during which time cyprinids replaced coregonid fishes, blue-green
algae succeeded diatoms as dominant phytoplankters, and oxygen was
reduced in deep water (Minder, 1926, '38, '43).  Some other European
lakes have had similar histories (Hasler, 1947).  Cultural enrich-
ment has also affected a number of North American lakes, but few of
them were studied before they posed problems.  The Yahara River lakes
near Madison, Wisconsin; Lake Sebasticook, Maine; and Lake Washington
near Seattle have probably received as much attention as any (U.S.
DHEW, 1969; Hasler, 1947, Sawyer, 1947; Edmondson 1961, 'bo, '68).

     It has been proposed (Livermore, 1954) that nutrient content of
lakes may be reduced by removing large quantities of aquatic plants.
Weed harvest has generally been concerned with clearing lakes and
canals for recreation and navigation (e.g. Blanchard, 1965), but some
attention has been given to water weeds as livestock feed (Bailey,
1965; Lange, 1965).  Yount (1964) and Yount and Grossman (1970)
suggested that aquatic plant harvest was one of the more promising
solutions for reducing lake productivity.

     In 1968 the National Eutrophication Research Program, Federal
Water Quality Administration, funded a study on Lake Sallie, Minnesota
of the effects of large scale weed harvest on lake nutrient content.
A research grant was awarded to the University of North Dakota to de-
termine the basic limnological nature of this lake and varied effects
of weed removal.  This article, largely based on data appearing in
Peterson (1971) and Smith (1972), comprises the final report on this
project.

Present addresses:

     Spencer A.  Peterson
     U.S.  Environmental Protection Agency
     Pacific Northwest Environmental Research Laboratory
     Corvallis,  Oregon  97330

     Wintfred L.  Smith
     Department of Biology
     University of Tennessee at Martin
     Martin,  Tennessee  38237

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                           STUDY AREA

     Lake Sallie (Fig. 1) has received nutrients supplied by waste-
waters from the city of Detroit Lakes, Minnesota (1970 population
nearly 7,000) for more than 60 years  (Larson, ;1961).  Waters enriched
by these wastes, which are now treated by, settling, biofiltration,
aeration, a stabilization pond, and flow through a peat bed, in that
order, follow a somewhat circuitous route into Lake Sallie, that
requires passage through 2 other lakes (Fig. 2).  This city also exper-
imented with lime precipitation and spray irrigation as means of nutrient
removal, but abandoned the first after facilities proved inadequate and
the second when data collection arrangements failed.  Civil suit brought
against the city in 1951 by lake property owners was dismissed for lack
of evidence, but the city is now under orders from the Minnesota Pol-
lution Control Agency to reduce nutrients, especially phosphorus, to
noncritical levels.  One hundred and sixty eight cottages along the
shores of Lake Sallie, occupied for varying periods during the year,
discharge wastes to individual septic tanks usually situated in ground
areas draining to the lake.

     Lake Sallie is part of the Pelican River lake chain in north-
western Minnesota, which is contributory to the Ottertail River and
the Red River of the North.  The topography of the Pelican River water-
shed was primarily determined by Wisconsin glaciation during the Pleis-
tocene Epoch, which sent at least 4 lobes of its ice sheet into Minn-
esota.  The Wadena lobe, which moved  into the area from the Northwest,
and the Des Moines lobe, advancing along the Red River Valley, were
chiefly involved in formation of this watershed.  The Wadena lobe formed
the hilly region (Fergus Falls Moraine) to the east, and as it retreated,
the Des Moines lobe, moving east from the Red River Valley, overrode  this
moraine and carried till with it.  Withdrawal of the latter lobe added
to deposits on the Fergus Falls Moraine and formed outwash areas to
either side of it  (Fig.  3).  This hilly, glacial overlap region is known
as the Alexandria Morainic Complex  (Wright, 1962).  Melting of buried
blocks of ice formed  the lakes  (kettle basins) as the glaciers retreated.

     A thick layer of glacial drift now lies within the Pelican River
watershed (Fig. 3).  Outwash gravel forms the central area, with till
on either side.  Glacial drift exceeds 91 m in thickness in the general
area, and outwash deposits vary from  1 to 24 m or more in  thickness
 (Allison, 1932).  Watershed soils range from well drained, medium
textured sandy loam developed from calcareous, buff colored glacial  till
on the east  to dark-colored coarse  to medium textured material, formed
from outwash near the center, to well drained dark soil produced from
calcareous galcial till  on the west  (Reedstrom and Carlson, 1969).

     About 45% of the Pelican River Watershed is used for  agriculture
 (small grains, hay, and  pasture), water and marsh areas comprise 297o,
forests  2370, and urban and residential areas 37o.

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      Lake Sallie is kidney-shaped with its long axis lying north-
 east to southwest (Fig. 1).  The area lying north of its indentation
 (hilus) has a somewhat irregular bottom formed by depressions and
 elevations, while that south of the hilus is practically flat below
 the shoreline slopes.  The deepest area in the lake lies between
 these two distinctive areas, east of the indentation.  The Pelican
 River enters through Muskrat Lake, which was formed by a dam, with
 weirs for water level control, across the river inlet.   Lake Sallie
 has the following dimensions:

                  Area - 5.30 km2 (1309.6 acres)
                  Length,  total - 3.32 1cm (2.06 mi.)
                  Width, Maximum - 2.01 Ion (1.25 mi.)
                  Depth, Maximum - 16.5 m (55 ft.)
                  Depth, mean - 6.35 m (20,86 ft.)
                  Volume - 33.7 x 106m3 (1.18 x 109 ft.3)
                  Shoreline, length - 9.5 km (5.9 mi.)
                  Shore development - 0.65

      Area and volume have the following magnitudes at the listed
 depths:
Depth
m ft
0 - 1.52
1.52 - 3.05
3.05 - 4.57
4.57 - 6.09*"
6.09 - 9.14
9.14 - 12.19
12.19 - 15.24
15.24 - 16.50
0- 5
5-10
10-15
^.5-20
20-30
30-40
40-50
5U-55

Area
m2 ft2
5,300,000
4,460,000
3,410,000
3,020,000
2,660,000
290,000
30,000
10,000

57,145,472
47,998,712
36,708,996
32,545,043
28,659,848
3,101,187
331,026
87,112
Totals :
Volume
m3 ft3
8,069,397
6,776,281
5,183,360
4,595,619
8,093,996
875,824
93,486
12,299
33,700,262
284,930,408
239,270,482
183,024,441
162,271,306
285,798,998
30,925,345
3,300,990
434,277
1,189,956,247
% of
total
23.94
20.11
15.37
13.64
24.02
2.6C
0.28
0.04
100
     At the ^ginning of this investigation Lake Sallie had luxuriant
summer growths of rooted aquatic plants extending out to the 3 m  (10
ft.) contour and some patches of Potamogeton praelongus extending out
to 6 m (18 ft.).  Weeds covered about 34% of the total bottom area.

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     The lake is situated in a transition zone between boreal forest
and western prairie, and water quality is somewhat intermediate between
that of the forest and prairie, leaning more toward that of the former,
which is considered hard, whereas that of the prairie region is classed
as alkaline (Moyle, 1945, '56; Allison, 1932).  This region has rather
warm summers and cold winters.  Over the period 1946-60 mean daily
minimum temperatures occuring in January averaged -15.1°C (4.9°F) and
mean daily maximums recorded in July averaged 21.2°C (70.1°F).  During
this time average annual precipitation was 49.86 cm (23.57 in.).
Evaporation exceeds precipitation by about 25.4 cm(10") per year.  About
68% of the annual precipitation occurs from May through September.  Depth
of winter snowfall varies, as does thickness of ice on the lake, depend-
ing upon precipitation, wind, and temperature patterns.  In 1968-69 ice
was unsafe for walking on a large central area, but in subsequent winters
it has become thick enough to permit foot and vehicle travel to all parts.

     It was assumed that knowledge of major limnological characteristics
prior to and following weed harvest in this lake with a long history of
enrichment would indicate environmental consequences of weed removal as
well as its efficiency in reducing nutrients.

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                     MATERIALS AND METHODS

     The basic plan was  to  determine major  limnological characteristics
of the lake,  then harvest weeds and ascertain what changes were brought
about.  Amounts of nutrients  removed in weeds would also be ascertained.
Details follow:

                            Sampling

     Sampling was carried out at  the 21 sites shown in Figure 4, with
frequency varying from daily  to semi-weekly  to weekly in summer and
from weekly  to biweekly  in  winter.  Postponements were caused by unsafe
ice in early and late winter, and occasionally by adverse winter weather.
The surface  was included at all sites and varied depths down to 16 m at
selected sites in the limnetic zone, in order to monitor depth and
duration of  thermal stratification and its  chemical and biological effects,

                       Physical Features

     Temperature and light  penetration were  routinely measured, the
former with  a thermistor thermometer and the latter with a submarine
relative irradiance meter with green, red,  and blue filters.  Measure-
ments were made during open water seasons and under ice.  Discharge in
and out of the lake was  recorded  by the U.S. Geological Survey, St.
Paul, Minnesota, and weather  data were obtained from Radio Station KDLM,
4.5 kilometers (2.8 miles)  NE of  Lake Sallie.  Solar radiation was
monitored in 1971 with a pyranograph.

                       Chemical Features

     Samples  were taken  with  a Kemmerer Sampler (plastic) and transferred
to iced chests in summer and heated ones in winter for transport to a
lakeside laboratory for  immediate performance of the following analyses:
carbonate and bicarbonate alkalinity, total, calcium and magnesium
hardness, ammonia, nitrite, and nitrate nitrogen, total phosphorus,
orthophosphate, and oxygen.  Oxygen was also measured in the field by
dragging a galvanic cell probe along a series of transects extending
across and up and down the  lake.  All analyses except total P and N03
were according to Standard  Methods, 12th edition (A.P.H.A., 1965).
Total phosphorus was according to Krawczyk  (1969) , and NO^ to Strickland
and Parsons  (1965).

     Aquatic  macrophytes were prepared for  analysis by drying and mill-
ing to pass  a 60 mesh screen.  Nitrogen and  carbon were determined with
a hydrogen-nitrogen-carbon  gas analyzer and  total phosphorus with the
one solution  ascorbic acid  technique (Strickland, and Parsons, 1965),
with persulfate digestion.  Sediment samples were air dried and anlyses
were performed on the materials fine enough  to pass through a 60 mesh
screen.  Total nitrogen was determined by the modified micro-Kjeldahl
method of Koch and McMeekin (1924) for some  sediment samples.  Phosphorus

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was extracted w'.uh G.GNHcl, and, after filtering 'and dilution, tested
with standard reagents.  Twenty eight samples of 11 species of macro-
phytes had Ca, Mg, Na, K, Co, Gu, Fe, Mn, No, and Zn measured.  Peri-
phyton was normally included with macrophytes. ' Ca, Al, and Fe of some
sediment samples were determined by the metho'd 'of Chang and Jackson
(1957).  Nutrient analyses of fish flesh were'performed on dried-samples
of ground whole fishes, using the same methods described for plants.

     Sediment samples to a depth of 15 cm (6") were taken with an
Ekman dredge and air dried and graded with sieves prior to analysis.
Aquatic macrophytes were collected by hand prior'to weed harvest, but
after this process was underway 0.024 cubic meter (1 cu. ft.) samples
were picked off the harvester apron, dried, grated through 6.35 mm
(1/4") hardware cloth, and portions of them analyzed.  These samples
contained periphyton, snails, insects, crustaceans, and small fishe
in addition to weeds, and represented all materials removed by the
harvester.

                      Biological Features

     Weed areas were mapped prior to harvest by collecting along a
large number of transects extending across weed beds perpendicular to
shore.  Dominant species were noted for each  area.  Plankton was
collected in several regions, but most sampling was confined to the
deepest lake area where samples were vertically spaced at 2 m intervals
in the euphotic zone and at varying depths in the aphotic.  Samples of
4 1 were concentrated to 200 ml by settling.  Counts were made in
Sedgewick - Rafter cells, using the strip method for common forms and
counting the whole cell for rare organisms.   Plankton units were 1
ocular grid (.49 sq. mm) for large irregular  colonies, 100 micron
lengths for filamentous algae,  individual colonies for such organisms
as Pediastrum and Crucigenia, and individuals for single celled algae
and zooplankters.

     Primary production by plankton, net and  gross, was measured by
oxygen change in light and dark bottles filled with water from varied
depths in the euphotic and aphotic zones and  returned to these depths
for incubation, which was for 2 hour periods, except during colder
seasons with low plankton densities, when it  was 6 hours.  Results were
converted to mg C fixed/cu.m/hr.  Primary production by macrophytes and
their investing periphyton was  arrived at by  isolating an area of lake
bottom and its vegetation in a  large cylinder of clear vinyl  film and
noting changes -in pH, free CC^j and alkalinity at frequent intervals
(usually 2 hours) in the enclosed water.

     Light and dark bottles were filled and  suspended inside  the
cylinder to estimate changes attributable to  phytoplankton.   Calcula-
tion was as follows:

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     CVP = A or B x 0.27 - CP

where

     CVP = Carbon fixed by vascular plants and their periphyton  (mg/m3)
       A = free CC^ used (mg/m3)
       B = Carbonate increase + total alkalinity decrease (mg/m3) x 0.44
      CP = Carbon fixed by plankton (mg/m3)

     At the end of incubation a volume of water was taken from the
cylinder for membrane filtration and determination of plankton dry
weight, and all attached vegetation was removed from the cylinder to
ascertain its dry weight.

                        Weed Harvesting

     Weeds were removed with a mechanical cutting, loading and unload-
ing maching (Marine Scavenger Model 258-11) manufactured by Aquatic
Controls Co.  This unit has a capacity of 11.363 kg (25,000 Ibs.) per
hour, a pay load of 3.636 Kg (8,000 Ibs.), a draft of 41-61 cm (16-24
inches), and can cut to a depth of 1.52 m (5 feet).  Minimum practical
working depth is about a meter  (3.28 ft.).  The lake was divided into
9 harvest areas (Fig. 6), and loads removed from each were recorded.
Twenty nine harvester Loads were weighted wet, and 0.024 m3 (one cubic
foot) samples removed from them were weighed wet, dried, and reweighed.
Wet harvester load weights divided by wet weights of 0.024 m3 samples
allowed computation of number of cubic units per load (m3 or ft3).  Wet
and dry weights of 0.024 m3 samples were then applied to harvester
loads to determine total wet and dry weights removed from each area
and the lake.  This size samples were taken from many harvester  loads
that were not weighed.  Nutrient loads per harvest area and lake were
computed from their concentration in dried samples.

     The weed harvester was also used in mapping macrophyte distribution
and determination of standing crop.  A standard length of line,  floated
and marked at set intervals was used to guide the harvester over a
known area 2.4 x 91 meters (8 x 300'); and any species changes with
distance along each cutting transect could be referred to the nearest
line marker.  Chemical sampling sites are shown in Figure 4, locations
of oxygen transects in Figure 5, and weed harvest areas in Figure 6.

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                           DISCUSSION

                    Climatological Features

     Climate during the period of .this study differed somewhat from
norms established over 1946-60.  Average January and July temperatures
were slightly lower than these norms.  Total annual precipitation was
below normal in 1969 and '70 but above it in 1971.  Months with great-
est precipitation were July 1969, June 1970, and September 1971 (Table
1).

                       Physical Features

                           Ice Cover

     Ice cover endured from around mid November until Mid April each
winter.  Ice became covered with snow that varied from 40 (1968-69)
to 12 (1969-70) to 5 inches (1970-71).  There was some drifting during
the last winter giving 24.5 cm (10 inches) of snow in some areas.
Heavy snowfall occuring during early freezing in 1968 reduced ice thick-
ness to as little as 15.24 cm  (6 inches) on central lake areas, and
produced an opaque spongy ice except near shore.  Ice formed during
subsequent winters was clear and firm and varied from 61-91 cm (24 to
36 inches) in thickness.  Noticeable surface flooding of ice occured
in March 1971.

                          Temperature

     Water temperature responded rather quickly to seasonal air temp-
erature change, and there were generally distinct differences between
temperatures of surface and deeper waters in summer and winter (Figures
7 and 8).  Thermal stratification (summer stagnation) endured continually
from mid July until September 1969, when the thermocline varied from 5
to 8 m in depth.  In 1970 a thermocline that became established June 6
disappeared 20 days later and did not recur.  In 1971 a thermocline was
present in early May, again on June 3, to June 10, then again from June
15 until July 21, and finally from August 12 to August 20.  Its position
and thickness during these periods appear in Figure 9.  Winter stagna-
tion was well developed each year (Figures 7 and 8).

                  Light and Light Transmission

     Solar energy was recorded, with a few interruptions, from June 8
to December 23, 1971.  Mean daily values in langleys were:  June, 477;
July, 559; August, 502; September, 348; October 187; November 132; and
December, 103.  The maximum daily value, 708 langleys, occurred July 5,
and the minimum, 42 langleys, December 1.  Surface light intensity
(total) varied from 402 to 7,153 foot candles at times of light penetra-
tion measurements.  Total light intensities (as 7o of surface irradiation)
at depths of 1 and 3 m varied during open water seasons over the 3 year
                                10

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period (Figure 10), and no light was observed to penetrate ice cover,
even the minimum (around 24.5 cm or 10 in.) considered safe for
observers.  Light penetration during open water seasons was commonly
restricted by trubidity due to plankton growth, especially blue-green
algae near the surface.  The 1% level of incident radiation usually
occurred at 3 to 3.5 m, but in autumn sometimes reached 8.5 m.  Very
faint light was sometimes detected at 10 m.  Penetration of green, blue,
and red wave lengths varied over the seasons, with green and red usually
with greater intensity and range (Figure 11).  Red was sometimes notice-
ably stronger than green near the surface, but green usually accounted
for most light intensity at depths of 2 m and greater.

                            Sediment

     Shoal areas, which comprise about 45% of the bottom area, are
largely sand, and deeper areas are largely covered with silt and
clay, having a gyttja consistency when wet (Figure 12).  Bars of cobble
sized rocks and sand extend out from shore in some areas.

                       Chemical Features

                           Lake Water

Hydrogen Ion Concentration

     Surface waters of the limnetic area of Lake Sallie had pH values
well above 8.0 at all seasons during open water and under ice and snow
cover (Figure 13).  Deeper water pH fell below 8.0 during summer and
winter stagnation but rose above 8.0 during periods of full circulation.
Littoral areas, especially those affected by ground and surface inflow,
e.g. the Pelican River, Fox and Monson Lake discharges, and Station 9
often had pH below 8.0; but at times had the highest pH recorded  (up to
9.7).  Low values occurred in winter when anaerobic or nearly anaerobic
waters built up in these areas, and high values in summer with acceler-
ated photosynthesis responding to inflow nutrients.  Surface pH in the
limnetic zone rarely exceeded 9.0, reaching 9.2 on a few occasions in
1969.

     These pH data indicate a virtual isolation of most upper waters
from areas with greatest decomposition over most of the year, wide-
spread effects of photosynthesis in upper waters, and relatively minor
water volume (in littoral areas and in a few deep pockets) undergoing
pronounced changes due to decomposition.  Persistence of high pH  in the
absence or near absence of photosynthesis under ice and snow further
attests to the general low level of decomposition.  Upon a few occasions
a minor pH increase (0.1 pH) occurred in water in contact with the ice
cover, and it is assumed that these elevations were due to photosynthesis
since they were usually accompanied by slight increases in carbonate and
oxygen.   Winter sampling occurred at weekly and biweekly intervals, and
although no light penetration through ice was recorded, it could have
                                11

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occurred between sampling dates.  There was usually a slight pro-
gressive decline in surface water pH with time under ice cover in the
limnetic zone, with a few interruptions occasioned by rare.periods of
photosynthesis.

Alkalinity

  Carbonate

     As may be inferred from the above account of pH, carbonate occurred
in surface waters of the limnetic zone at all seasons, was absent from
deeper waters during summer and winter stagnation, and from some littoral
areas at intervals.  Its concentration reached 100 mg/1 (as CaCO^) in
Muskrat Lake discharges and attained 48 mg/1 in the limnetic zone.  It
increased slightly under ice cover when pH and oxygen changes indicated
photosynthesis, as would be expected.

  Bicarbonate

     This ion had its minimum recorded concentration in surface waters
of the limnetic zone when photosynthesis was most pronounced and achieved
its maxima for this zone in deeper waters during winter stagnation.  The
most recorded in the limnetic zone was 230 mg/1 during winter, but Stations
9 and 21 in the littoral zone and Station 1 in Muskrat Lake discharge
often exhibited higher values under ice.  The highest recorded value was
428 mg/1 at Station 9 in January 1971.  That area appeared to receive
considerable ground water during winter, or this water was more isolated
there under ice.  During open water seasons photosynthesis was noted to
reduce bicarbonate to 124 mg/1 in surface water of the limnetic zone.
In most waters this much bicarbonate would provide sufficient C02 for
photosynthesis and there seems no reason to suspect that it would be
limiting in Lake Sallie.

Hardness

     Total hardness varied above and below total alkalinity in concen-
tration suggesting that at times cations other than those contributing
hardness were combined with carbonate and bicarbonate.  From October
1968 until June 1969 hardness continually exceeded alkalinity in surface
water of the limnetic zone, but this was not true for the remainder of
that growing season, nor for the 1969-70 winter, nor for the 1970 open
water period.  In autumn of 1970 and early in the 1970-71 winter hard-
ness overshadowed alkalinity in upper limnetic water, but alkalinity
pulled even in late December and went ahead in early January. t Hardness
came to the fore again in early February and was thereafter greater
than alkalinity until early June 1971, when it fell slightly below.  It
became dominant again in late June and remained so through December 31,
19.71.  The hardness maximum recorded in surface limnetic water during
1970-71 was 225 mg/,1, whereas that of alkalinity was 206 mg/1.  Minimums
during the same period were 167 hardness and 149 for alkalinity.  Alka-
linity exceeded hardness by as much as 8 mg/1, but hardness was greater
                                12

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 then alkalinity by as  much as 25 mg/1.

      Hardness  and alkalinity were rather uniform from surface to
 bottom during  periods  of complete circulation,  but both changed with
 depth during times of  stagnation.  The  usual tendency then was to
 increase  with  depth, and this appeared  generally true when upper-  and
 lowermost waters were  compared,  but there were  several occasions when
 intermediate waters were lower than those above and below;  and there
 were 2 periods during  the 1969-70 winter when lenses of harder water
 appeared  to flow through the limnetic zone at a depth of 2 meters.
 When they disappeared  no hardness increase was  noted at 4 or  6 meters,
 and  it is assumed that they moved out of the sampled area (Station  4)
 laterally.   Inflow of  the Pelican River has at  times exhibited hard-
 ness concentrations very near those of  these lenses,  and it seems
 reasonable that its discharge may pass  through  the lake as  an inter-
 flow when ice  cover stills wind  driven  circulation.   With one excep-
 tion,  which may have resulted from an analytical error,  hardness and
 alkalinity augmentation occurred in surface water under ice cover and
 likely represented retention of  freeze-out in the upper,  lighter
 water.

      Both hardness and alkalinity varied in different regions of the
 littoral  zone,  especially when mixing into lake water was slowed by
 ice  cover.   Ranges on  three occasions in late winter at 12  alongshore
 stations  in mg/1 were:

        Date                   Total Alkalinity              Total Hardness

      3/15/69                     198 -  242                    210 -  250

      2/06/70                     196 -  326                    215 -  323

      3/07/70                     182 -  408                    196 -  372

      Highest values occurred at  Station 9,  where concentration
 diminished rapidly with distance from shore.  Maximum concentrations
 recorded  there  were 428 mg/1 alkalinity and 431 mg/1  hardness  in
 January 1971.   Concentration at  most shoreline  stations  decreased
 abruptly  when wind driven circulation returned  with  ice  melt.   Areas
 most  dominated  by inflowing water (e.g.  Station 1 at  the  Pelican River
 inlet) tended  to remain more mineralized than the lake,  but they were
 reduced to  the  general  limnetic  level by strong winds.   Hardness and
 alkalinity  were generally most concentrated during the  winter and most
 dilute during  open water seasons in surface and deeper  waters  (Table
 2).

 Calcium and Magnesium

      In limnetic  water  calcium (as  CaCO^)  varied from slightly less
 than 60 to  almost  100 mg/1  (Table 2).   Greatest concentrations  noted
were in deep water  during times  of  stagnation.   Magnesium exhibited a
                                13

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similar pattern of variation, but its range was noticeably higher, from
108 to 147 mg/1 in 1970-71.  Littoral stations attained greater concen-
trations of both ions under ice cover, and at times in some of those
areas calcium attained greater concentrations than magnesium.  These
occurrences suggest that ground water entering this lake system is
normal for this general area in having more calcium than magnesium, and
this has been confirmed by analyses of well water in 1972.  Preponder-
ance of magnesium in a lake fed by such ground water indicated photo-
synthesis overshadowing decomposition in magnitude and placing the
more soluble MgCO^ in a more favorable position than CaCC^ to recombine
with CC>2.  This condition has been noted in other eutrophic lakes in
this general area.  Both ions increased when C02 appeared in bottom
water at Station 4, but magnesium to a greater extent.

Oxygen

     Level of oxygen in Lake Sallie was frequently determined by
photosynthesis and respiration.  During open water seasons the entire
lake surface commonly exhibited oxygen pulses with concentration
declining to near zero in the early morning hours and building up to
supersaturated values by early afternoon.  Greatest concentration (as
7o saturation) was usually produced by macrophytes and attached algae
in the littoral zone (out to 3 m depth), and, as would be expected,
lowest concentrations also frequently occurred in this area.  Strati-
fication in summer and winter frequently occasioned oxygen depletion
in deeper waters, but oxygen was always found in surface water, even
under heaviest ice and snow cover.  In fact, photosynthetic production
of oxygen occurred at intervals under ice cover, at one time giving an
increase of about 3 mg/1 between sampling dates, although light
measurement consistently indicated no penetration through the ice.
Carbonate alkalinity and pH increase accompanied oxygen elevations, and
there seems no doubt that photosynthesis was operative at those times.
Since photosynthesis occurred between visits it is assumed that light
penetrated ice at times that were missed by the sampling schedule
(Table 2).

Biochemical Oxygen Demand

     Maxima of this parameter appeared to normally characterize early
spring, late summer, and autumn in the limnetic zone, but peaks
occurred at other times in Pelican River inflow (Figure 14).  Increases
and decreases in BOD were rather closely associated with those of plank-
ton, and it would appear that suspended organisms and their detritus
were major contributors to BOD in the largest lake area.

Nitrogen

Ammonia

     This form of nitrogen was consistently present in all areas  and
depths sampled in Lake Sallie.  In the limnetic zone  it was most  con-
centrated in deeper waters during summer and winter stagnation  (up  to


                                14

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2.6 mg/1 in summer and to  1.5 mg/1  in winter).  Greater concentration
in upper waters  (1.25 mg/1) occurred during periods of full circula-
tion when maxima attained  in bottom waters during stratification were
reduced.  Surface concentration varied in different lake regions.
Highest values  (slightly above 4.0  mg/1) were observed at Station 9
under ice cover, which suggests that inflow there was contaminated,
but concentrations above the general lake level were also noted at
Stations 1, 12, 19, and 21.  These  ammonia values were induced by in-
flowing surface and ground water.   That entering at Station 1 represent-
ed by far the greatest volume, and  was considered most influential on
the character of the lake.  Concentration in the limnetic zone was
nearly always greater than 0.1 and  usually more than 0.2 mg/1 (Table
2).

Nitrite

     Nitrite was usually,  but not invariably, found in samples from
all areas, depths, and dates.  It disappeared in August 1969 from all
sampled areas,  and was missing at times in summer from some stations.
Its concentration was generally well below 0.01 mg/1 at all depths
during open water seasons, but it increased to 0.1 at Stations 1 and
4 for a short period in September,  1970.  With stratification maximums
(up to 0.1 mg/1 in March 1970) occurred at intermediate depths (6 to
8 m) under ice  and at intermediate  or maximum depth with open water,
when increases  rarely occurred below stable thermodines (Table 2).

Nitrate

     Nitrate was most concentrated  at all depths under ice cover,
when the maximum observed  concentration  (0.34 mg/1) occurred in surface
water at 3 stations.  Vertically in the limnetic zone, it attained
peak values at  6 and 8 m during winter of 1969-70, but during the 1970-
71 winter its maximum was  at 14 m.  Inflow via the Pelican River
generally had higher nitrate concentration than that leaving the lake.
Nitrate was rarely absent  from surface water, but zero values there
were noted during all seasons except under ice cover  (Table 2).

Phosphorus

     Available  phosphorus  (P04.) generally was most concentrated in
deeper waters of the limnetic zone, especially during periods of strat-
ification (the  9.2 mg/1 maximum was in the hypolimnlon in 1969), but
it tended to disappear from surface waters during the growing season,
although this occurred infrequently in 1969.  It varied markedly in
surface water at Station 1, where maximum values  (4.8 mg/1) occurred,
but it reached  comparable  levels in other littoral areas (Stations 9,
10. and 12) under ice cover.  Its maximum for the limnetic zone surface
(1.4 mg/1) occurred in September 1969.  Surface values there were
usually less than 0.20 mg/1.  Orothophosphate was consistently higher
in inflowing than in outflowing water^ declining to zero in the latter
for about 30 consecutive davs in Julv and August 1971.  Surface water
                                 15

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concentrations were higher in 1969 than in 1970 and 1971;

     Total phosphorus occurrence and variation generally paralleled
those of PO, , but its, concentration was substantially higher.  It
increased with depth, declined from winter maxima during the growing
season, and was almost always more concentrated in inflowing-than in
outflowing water.  Its level was also greater in 1969 than in 1970
and 1971.

Miscellaneous Water Chemical Features

     Sulfate, analyzed infrequently, had generally low levels (6.0 -
7.5 mg/1), but was about 3 times as concentrated (20.5, - 27.5 mg/1)
in inlet and outlet.  Reasons for increase at the outlet are unknown.
Conductivity, measured only once during summer stagnation, showed an
increase with depth,, (320 umhos at. 9,m).:,and was,,greatest in surface
water in Stations 1.and 9,. which was not amazing considering greater
mineral content at those stations.  Hydrogen sulfide measured at-1 m
intervals down to 15-'m at Station 4 on July 8, 1971, occurred only at
8 m and below, increasing from 0.1 at 8 m to 5 mg/1 at 15 m.

     The Pelican River above Muskrat Lake usually had more ortho-
phosphate, ammonia, and nitrate nitrogen than this lake's discharge,
but total P was more frequently greater in the discharge.  Evidently
a significant share of the PO, entering Muskrat Lake was incorporated
into organic matter before reaching Lake Sallie. , Analyses of the
Pelican River above and below where it receives. ,the ditch from St.
Glair  (see Figure 2) confirmed high nutrient content of- drainage
receiving Detroit Lakes waste water effluent.

     Rainwater collected near Stat,ion 1 in September and- October 1971
was acidic  (pH 3.8-4.2), at times contained PO^ (0.25 mg/l)-and always
bore nitrogen (NH3-N, .05-.75; N02-N, .004-.006; N03-N,  .054-.426
mg/1).  Ice and snow from atop the lake in November and December 1971
had .38-.52 mg/1 P04 and .053-.414 mg/1 N03-N.  Concentrations, in the
ice were considerably greater than those in surface water on dates of
collection.  Reasons for this increase are only speculative  at this
time.

     Samples taken  through ice in the littoral zone in the winters of
1968-1969 and 1969-1970 disclosed a lack of oxygen at Station 9.  A
transect run perpendicular to shore, there in March 1970 showed an oxy-
genless condition out to about 90 m from shore, but a rapid  increase
to 6-. 28 mg/1 at 105 m.  The anaerobic, zone also extended alongshore
for about 100 m on  either side of Station 9.

                           Sediments

     Nitrogen and phosphorus were considerably lower in sediments in
shallow than in deeper lake areas.  Nitrogen was about 4 times as
                                 16

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concentrated under 5.5 m than under 1 m or less of water, although
C:N ratios were little changed.  Total P was about 3.5 times more
concentrated under deeper water, largely in calcium and iron combin-
ations, with the latter more prevalent.  Aluminum P was significantly
less common, but was also greater under deeper water.  Calcium
phosphorus was 12 times as great as the water soluble fraction.  In
1970-71 sediment analysis was restricted to total N and total P, but
increases with water depth were still apparent (Tables 3, 4, and 5).

                      Aquatic Macrophytes

     Analyses of upper, middle, and lower one thirds (including roots)
of 8 species of rooted plants collected in September 1968 showed
rather uniform concentrations of most elements measured (P, N, C, H,
Ca, Mg, Na, K, Co, Cu, Fe, Mn, Mo, and Zn) throughout the plant,
although they varied in different species.  P was greater in upper
sections of Myriophyllum exalbescens .and Vallisneria americana; calcium
was most concentrated in Potamogeton Richardsonii and Elodea canadensis,
and the upper two thirds of Vallisneria; and sodium was highest in the
root sections of the four species whose lower 1/3 was analyzed (Scirpus
validus, Myriophyllum, Potamogeton pectinatus, and P. Richardsonii)
(Tables 6 and 7).

Weed Harvester Catches

     Organisms gathered by the weed harvester included aquatic macro-
phytes plus periphyton and any animals living in the vegetation.
Carbon content of this assemblage was rather uniform throughout the
lake weed beds in 1970 and 1971, as were nitrogen and phosphorous in
1971.  However, in 1970 P was 2.4 times as concentrated in Area 1 than
in areas 8 and 9 and exhibited a gradual decrease around the lake
counterclockwise from Station 1.  Nitrogen was more concentrated in
Areas 1 and 2 in 1970.  Ranges in ppm per dry weight of weeds were as
follows:  1970. p, 1,900 - 4,500; N, 21,000 - 29,900; C, 277,000 -
370,000.  1971. P, 2,200 - 3,450; N, 18,300 - 32,000; C, 294,000 -
336,000 (Table 7).

                              Fish

     Ten species of fish were analyzed in toto for P. N, and C.  Sun-
fishes (3 species) had higher levels of P than perch, walleye, pike,
white sucker, or bullheads (3 species).  Range among these species
was 0.49 - 0.85% wet weight.  Nitrogen (range 1.83 - 2.61% wet wt.)
and carbon (range 7.91 - 9.97% wet wt.) showed no marked relationship
to fish species.

                            Plankton

     Plankton, including detritus, was analyzed only for phosphorus.
P tended to be more concentrated in plankton from the upper 2 m of the
limnetic zone, but at times was about as concentrated in spspended
                                17

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matter from deepest water.  It varied from place to place in samples
from surface water, once achieving 47,000 ppm per dry weight at
Station 12.  Plankton from the limnetic zone had markedly lower P
concentrations in fall than in summer, but seasonal trends were much
less marked in the littoral zone.

                      Biological Features

                            Plankton

Qualitative Features

     Collections made over the three year period yielded 188 plankton
organisms that are listed in the appendix.  Green algae, largely
chlorococcales, accounted for the largest number of species  (59);
diatoms had 38, blue-green algae 25, ciliate protozoans 21, and
rotifers 19 species.  Less numerous groups, copepods (3), cladocerans
(7), suctorians (2), amoeboid protozoans (4), dinoflagellates  (3),
cryptophyceans (1), euglenophytes (3), chrysophytes (1), xanthophytes
(1), and identifiable bacteria (1), gave 26 species.

Seasonal Occurrence

     Seasonal patterns were usually considerably modified by location
in the lake, and sometimes were unstable during periods with chang-
ing dominant groups.  In the limnetic zone, as exemplified by  Station
4, the general tendency appeared to be dominance by diatoms in spring
giving way to blue-greens in summer to diatoms again in autumn and
early winter and to green algae  (Chlamydomonas) and/or pyrrophytes
(Cryptomonas) in winter.  However, this was by no means a fixed order
of succession.  For example, Microcystis (a blue-green) replaced
Chlamydomonas as the dominant plankter in surface water in February
1971,-but was replaced by the latter in March.  Chlamydomonas  did not
loose dominance in deeper water.  In June 1971, dominance changed from
Stephanodiscus (a diatom) to Microcystis, back to Stephanodiscus, and
then to the blue-greens Anabaena and Aphanizomenon.  Blue-greens, with
Gomphosphaeria and Oscillatoria entering dominant ranks in August and
September, were thereafter most prevalent until late September when
they were replaced for about 10 days by the diatoms Melosira and
Stephanodiscus.  Aphanizomenon regained dominance in surface water on
October 1, and was only slightly less numerous than Stephanodiscus at
2 m, but it was "ousted" for good by the latter on October 9.  This
diatom gave way to Chlamydomonas on December 11, and eleven  days later
this green alga was joined by Cryptomonas, which had also appeared in
dominant ranks with Aphanizomenon in surface water on October-'1.
Vacillating dominance between blue-greens and diatoms in late  spring
and early fall suggests that competition between them is rather  finely
balanced and that swings to either side may be occasioned by minor
environmental changes.  In August 1969 a dense Aphanizomenon popula-
tion was severely reduced by applications of copper sulfate  along the
                                 18

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southeast shore, and, when effects of this algicide wore off,
Aphanizomenon was replaced in dominance by Melosira, which achieved
even greater concentrations,  frlelosira was gradually replaced by
Stephanodiscus, which became dominant in mid-October.  This applica-
tion of algicide resulted in diatoms assuming dominance about 2
months earlier than they did in succeeding years (Figure 15).

Variation in Surface Water

     Plankton composition, even with regard only to major groups,
exhibited considerable variation at any time in both littoral and
limnetic zones.  In August 1969 blue-greens comprised 90% of the
population at Station 1, 10% at Station 2, 5% at Station 4, 2% at
Station 8, and 20% at Station 11.  For the same period diatoms were
2% at Station 1, 40% at Station 2, 85% at Station 4, 38% at Station
8, and 40% at Station 11.  Greens ranged from 1 - 30% of the popula-
tions at these stations, and other groups from 4 to 30%.  In June
1970  (1 series of samples) composition was as follows:  Station 1,
42% blue-greens, 58% diatoms; Station 2, 35% blue-greens, 63% diatoms,
others 2%; Station 4, 72% blue-greens, 23% diatoms, 2% greens, 2%
dinoflagellates, and 1% others; Station 8, 25% blue-greens, 65% diatoms,
3% greens, 5% dinoflagellates, and 2% others; and Station 11, 80%
blue-greens, 18% diatoms, and 2% others.  Hence, seasonal dominance
varied with  location, and neither littoral nor limnetic zone exhibited
any general  uniformity.

Variation with Depth

      Frequently the  group dominant at the surface was also prevalent
all the way  down to  10 m, although with as much as  30% variation in
degree of dominance.  On other occasions  dominance  changed to another
group at an  intermediate depth and back to the surface dominant in
deepest water.  In August 1969 diatoms  formed from  90 - 98%  of the
population down to 3 m,  2%  at 5 m  (where  blue-greens amounted to 98%),
98% at 7 m,  and 95%  at  5 m.   Zooplankters were concentrated  in deeper
water at times, and  Coleps was often  conspicuous  in these build-ups.
In September 1969 diatoms were dominant and varied  from 52%  of the
population at  2 m to 80% at  8 m.  Blue-greens, second in abundnace,
varied from  10  to 25% of the  populations  having both minimum and
maximum values  at intermediate depths.  Greens had  2% of the population
in deepest water and 15% at  2 m;  dinoflagellates  ranged  from 0 -  15%
of the populations at varied depths,  being most numerous at  4 m;  and
zooplankters varied  from 1  -  18% with most numbers  in  deepest water.
In summer of 1970 blue-greens were  dominant  at  all  depths, but they
were  replaced  at all  levels  except  1  m  by diatoms  in October.

      At  the  generic  level variation was  often rather marked  during
periods  of  dominance by one  of  the  larger groups.   For  example,  on
July  5,  1971,  Aphanizomenon,  dominant in  upper water, was  replaced by
another  blue-green,  Gomphosphaeria,  at  6  m,  and by Gomphosphaeria and
                                 19

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Coleosphaerium, still another blue-green, at 8 m.  Generic variation
within a major group also occurred in different littoral and limnetic
regions.

Quantitative Features

     Concentration in samples from the limnetic zome varied from more
than 55,000,000 to 12,000 units per 1.  Seasonal influences, insofar as
these may be determined from only 3 years records, appear to result in
spring, summer, and autumn maxima, with winter, late spring, and late
summer minima.  Diatoms have been largely responsible for the spring
and fall elevations and blue-greens for the major summer growth, but
diatoms replaced blue-greens in summer of 1969 following an application
of algicide.  Green algae exhibited about 5 peaks per year, three in
summer and one each in spring and winter.  They achieved dominance only
in winter, but they were more numerous than diatoms during summer, except
in 1969.  The greatest concentration observed, 55,114,200 units per
liter occurred at 6 m in the limnetic zone during a spring diatom
maximum, and diatoms comprised 99.770 of the total population.  Diatoms
were also dominant in surface and near surface waters, but their con-
centrations were somewhat less, being 50,657,500 per 1 at the surface
and 42,802,600 at 2 m.  Greater concentration at 6 m may have been due
to settling.  The highest observed summer concentration when blue-
greens were dominant was slightly more than 6,000,000 per 1.  Phyto-
plankters were several times as concentrated in spring of 1971 than
during either preceeding year, but summer densities were comparable
to those of 1969 and 1970 (Figures 16, 17, and 18).

     Lake Sallie, although with a long history of cultural eutro-
phication, was not dominated by blue-green phytoplankton except on a
seasonal basis, and this seasonal dominance did not appear very firm,
but rather finely balanced against incursion by diatoms.  Green aglae,
even when dominant, never attained numbers near those reached by
diatoms and blue-greens at their peaks.

                      Attached Vegetation

     Chara sp. grew on the bottom and Cladophora sp. and Gleotrichia
natans  (Hed.) Rab. were attached to aquatic flowering plants.  Star
duckweed  (Lemna Trisulca L.) grew both free floating and attached to
other vegetation, but other duckweeds  (Lemna minor L., Spirodela
Polyrhiza  (L.) Schleid., and Wolffia columbiana. Karst.) were all surface
floaters.  Macrophytes observed were;

                 Najas flexilis  (Willd.) Rostk. & Schmidt
                 Potamogeton amplifolius Tuckerm.
                 £. crispus L.
                 P_. filiformis var. Macounii Marong.
                 P_. pectinatus L.
                 £. praelongus Wulf.
                                 20

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                 _P. Richardsonii  (Benn.) Rydb.
                 Ruppia maritima  L.
                 Alisma gramineum var. Geyeri  (Torr.) Sam.
                 Scirpus actus Muhl.
                 Heteranthera dubia  (Jacq.) MacM.
                 Elodea canadensis Michx.
                 Vallisneria americana Michx.
                 Ceratophyllum demersum L.
                 Myriophyllum exalbescens Fern.
                 Nuphar variegatum Engelm.
                 Nymphaea tuberosa Paine

     These macrophytes covered about  34% of the total lake area, all
above the 3 m contour except Potamogeton praelongus which grew down
to 6 m  (Figure 19).  In 1969 and  '70  Myriophyllum and Potamogeton
pectinatus tended  to predominate, especially the former, in the
northern half of the lake and along  the south  shore.  Scirpus beds have
been prominent along the eastern  and  northern  shores and in a smaller
area on the west just north of the hilus.  Littoral areas in other lake
regions were largely covered by a mixture of Ruppia, Potamogeton Richard-
sonii, Vallisneria, and Ceratophyllum, in which other species were
widely  scattered.  Duckweeds were most conspicuous  in shallow areas,
especially near Scirpus beds.  Gleotrichia first appeared epiphytic
on macrophytes and later became free  floating.  It  and Nostoc became
very abundant on the bottom in late  fall.

     Weed distribution in 1971 was quite similar to that noted in '69
and '70, but all species, except  Scirpus, which was not harvested,
were noticeably less abundant.  Potamogeton pectinatus was more
prominent in weed harvester hauls and growth was most luxuriant in
Areas 3, 5, and 5, whereas in 1970 it had been greatest in Area 2
followed closely in Area 3.

Standing Crop

     Standing Crop of aquatic flowering plants and  their epiphytes,
based on weed harvester hauls from known areas in July and August 1971,
was estimated at 119,599 kilograms dry weight  for all weed bearing
areas (3470 of the  total lake area).   This figure includes roots which
had harvesting tests indicated were  13% dry weight  of the portion usually
taken by the harvester.  Average  dry  weight of harvester hauls was 58.8
g/sq. m.  The 1970 harvest was 2.9 times as great as that of 1971 for
comparable harvester effort.

                       Primary Production

By Phytoplankton

     Two hour exposure periods were  adopted as standard for light and
dark bottle tests, and duplicate  sets indicated this gave a precision
                                21

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 of +10 rag  C  fixed/m3/hr.

     Nutrient  concentrations  declined  along  the  course  of  the  Pelican
 River inflow into Lake  Sallie, and  this was  also true of the rate  of
 primary  production upon some, but not.all  occasions.  It was often
 greater  at Station 4  in the limnetic zone  than at Station  1 or in
 Muskrat  Lake.   Variation among stations in the limnetic zone appeared
 to be normal.

     Most  measurements  were made at Station  4 near the  heart of the
 limnetic zone.   Surface water there showed maxima in late  summer or
 early fall each year, but summer and fall  activity varied  noticeably
 over 1969-'71.   Average values for  the euphotic  zone gave  a three-year
 pattern  that resembled"that for surface water, but generally had
 sharper  and  fewer peaks.   In  1969 and  '71, means for the euphotic  zone
 maxima were  comparable  with highest rates  developed in  surface water,
 but the  average value was much below that  of the surface in 1970
 (Figures 20  and 21).  Surface productivity showed a progressive increase
 from 1969  through 1971  with respect to total amount of  carbon  fixed
 per growing  season.   These upper waters accounted for 68%  of pro-
 duction  at Station 4  over the three-year period.  Net production was
 greater  and  respiration less  in 1971 than  in '69 or '70 in both
 surface  water  and throughout  the euphotic  zone  (Figures 22 and 23).

     Productivity varied with depth in the euphotic zone  (Figure 24)
 and with time  of the  day (Figure 25) for which no pattern  appeared
 consistent.  There was  also no definite relationship with  intenstiy
 or amount  of light on either  a daily or a  seasonal basis,  but  photo-
 synthetic  efficienty  (mg C fixed per solar radiation unit) was great-
 est in  late  afternoon and in  early  September and during most of
 October  when solar energy was noticeably below values occurring in
 July and August (Figure 26).

 By Attached  Vegetation

     Measurements within the  plastic cylinder chiefly if not exclusively
 represent  the  activity  of flowering plants,  largely Myriophyllum,  and
 phytoplankton,  as very  few attached algae  were ever enclosed.   Depth of
 sampling and bottle suspension inside  the  cylinder was  10  cm.   Net
 productivity attributable to  the rooted plants  (total for  the  cylinder
 minus that for the light bottle suspended  inside) ranged  from  -338 to
 780 mg  C/m3/hr and that attributable to plankton from -119 to  503  mg
 C/m /hr.  On a net productivity per gram of  dry  weight  basis phytoplank-
 ton greatly  outstripped the rooted  vegetation, but dry  weight  of the
 rooted  vegetation included many more parts,  roots, fibers, etc., that
are  not  photosynthetic.   It is likely that  rates  for attached vegetation
 would have been higher  had attached algae  been enclosed with other plants,
 Thermal  and  oxygen stratification usually  developed within the cylinder.
 Light intensity declined markedly with depth inside the cylinder,  usually
 being less than 5% of surface values at  1  m  (Table 8).
                                 22

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                        Nutrient Removal
By Weed Harvester

     As mentioned previously, the weed harvester removed algae, in-
vertebrates, and fishes with aquatic flowering plants.  Total wet
weight of these organisms removed was greater for each area except
No. 5 in 1970 and 3.8 times greater for the entire lake as shown in
the following table:

                Kg  (wet weight) of Weeds Removed
Area
1
2
3
4
5
6
7
8
9
Total
1970
97,853
138,119
105,351
5,770
19,856
47,430
673
3,336
9,616
428,034
1971
6,578
1,928
31,477
1,850
54,711
14,520
0
0
0
111,064
     Dry weight of weeds removed amounted to 30,371 kg  (66,816 Ibs.)
in 1970 and 10,366 kg  (22,805 Ibs.) in  1971.  Kilograms of nutrients
taken out with weeds were as follows:
                              1970
1971
Phosphorus
Nitrogen
Carbon
100
721
10,699
26
248
3,219
                                23

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     Mean percentages of nutrients in dried weeds were:

                             1970              1971
p
N
c
0.27
2.34
32.25
0.265
2.46
30.73
     In 1970 weeds from Areas 1 and 2 (near the Pelican River  inlet)
had noticeably higher percentages of phosphorus and nitrogen than
those from areas farther down lake.  This was not true for P in  1971
when quantities available to the harvester in Areas 1 and 2 amounted
to but a small fraction of the mass removed in 1970, but weeds from
Area 1 still had the maximum nitrogen concentration.  In the 6 most
productive areas (1970) nitrogen ranged from 3 to 10 times the con-
centration of P, and C varied from 64 - 155 times as great as  P; in
1971 N was 4.5 to 10 times as great as P and C from 72 - 132 times.

Removed in Fish

     Commercial and sport fishermen took out 76,530 kg of fish (mostly
bullheads) in 1969-70, and 39,129 kg in 1970-71.  Mean concentrations
of P; N, and C in tested specimens were 0.53, 2.01, and 9.25%,
respectively, which would indicate that quantities removed were:

P
N
C
1969-70
406 kg
1,591 kg
7,109 kg
1970-71
207 kg
786 kg
3,619 kg
     Thus, 76,530 kg wet weight of fush contained slightly more than
4 times as much P, more than twice as much N, and slightly more than
2/3 as much C as 428,034 kg, wet weight, of weeds in 1970.  In 1971,
39,120 kg wet weight of fish gave almost 10 times the amount of P,
3.15 times the quantity of N, and slightly more C than 111,064 kg,
wet weight, of weeds.

     Costs per pound of nutrient removal by weed harvester were:

P
N
C
1970
$61.19
$ 8.24
$ 0.64
1971
$198.92
$ 21.04
$ 1.62
                                24

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     Costs include operation, maintenance, trucking of weeds to points
outside the drainage basin, and harvester depreciation.  Increased per
unit costs in 1971 reflect lower weed density.

                   Water and Nutrient Budgets

     Surface water enters Lake Sallie via the Pelican River (major
source) and outlets from Fox and Monson Lakes, and exits only via
the Pelican River.  Ground water inflow apparently exceeds seepage
from the lake, as surface outlow always exceeded inflow from the river
and lakes.  Quantities of water and nutrients entering and leaving in
surface flow appear below.

                                              Water Years

Water
Phosphorus
Nitrogen
Inflow m^
3
Outflow m
Inflow kg
Outflow kg
Inflow kg
Outflow kg
1968-69
20,197,256
22,716,382
10,140*
5,810*
11,650
9,720
1969-70
17,858,188
19,087,138
7,470**
2,510**
5,594
2,640
1970-71
17,849,207
20,807,164
15,643**
7,758**
10,567
7,217
     * Soluble P
    ** Total P
     1 NH3 - N + N02 - N + N03 - N

     Soluble P only was measured in 1968-69.  In subsequent years the
mean ratio of soluble P to total P was 1:1.7, and, if this may be applied
to the 1968-69 water year, total P entering then would exceed 17,000
kg and that leaving around 9,900 kg.  Both P and N declined noticeably in
1969-70, but recovered substantially in 1970-71.  P and N content of Lake
Sallie water was, in kilograms:

P
N
1968-69
2,270*
24,740
1969-70
9,690**
5,070
1970-71
16,513**
21,231
     * Soluble P
    ** Total P
                                25

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     Mean quantities contained in the upper 15 cm (6") of sediments
in 1968, '69, and '70, in kilograms, were 73 P and 748 N, whereas in
1971 they were 89 and 738 kilograms, respectively.  Total volume of
sediments to this depth is about 795,000 m c  Estimates of total wet
weight of fishes (Olson, 1971, !72) and quantities of P, N, and C
tied up in them, all in kg, follow:
                        1969
1970
1971
Fish
P
N
C
347,545
1,980
7,210
30,340
212,090
1,220
4,270
18,006
594,740
3,152
11,594
55,013
     The 1971 standing crop of aquatic flowering plants and organisms
gathered with them by the harvester, plus roots and lower stems not
taken by the harvester, has been estimated as 119,520 kilograms, dry
weight.  This figure is based on a mean standing crop of 66.4 g/sq. m.,
dry weight, over an area of 1,800,000 sq. m. (34% of the total lake
area).  Since percentages of P, N, and C in dried weeds were .30, 2.35,
and 30.87, respectively, total nutreint content of weeds and associated
organisms in 1971 was 358 kg P, 3810 kg N, and 36,920 kg C.

     Nitrogen and phosphorus budgets (Table 9) indicate that harvest of
fish and weeds to the extent possible with present equipment and practices
did not offset yearly gains via surface inflow.  Removal of all fish and
weeds would make an inroad on previously accumulated N, but would not
equal any annual P increment recorded to date. 'With the exception of
1969-70 much more N and P were contained in the water mass than in bodies
of organisms and sediments combined, and concentration of these two
elements would be subject to rather rapid reduction if their discharge
in wastewater to the Pelican River was curtailed.

                    Effects of Weed Harvest

     Two years of weed harvest did not alter the basic chemical nature
of the water mass nor the general pattern of nutrient dynamics in the
water.  One year's harvest greatly reduced weed concentration in affected
areas and occasioned some change in dominant forms.  Denser plankton con-
centration occurred the first year following harvest, the amount of
carbon fixed by phytoplankton increased, and the ratio of planktonic
respiration to photosynthesis decreased.  These latter developments suggest
that weeds compete with phytoplankton, and, that weed removal should not
be expected to aid phytoplankton control unless it depletes nutrient
supplies beyond annual increments.
                                26

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                        ACKNOWLEDGEMENTS

     Several persons and agencies gave invaluable assistance and
encouragement to this project.  The Minnesota Department of Conser-
vation provided laboratory and dock facilities and winter transpor-
tation at the Lake Sallie Fishery Station, and gave advice on many
matters from overall planning to equipment problems.  Indebtedness
is expressed to Dr. John B. Moyle, Director of Research, St. Paul,
and to the following Lake Sallie personnel:  William Joy, Manfred
Branby, Donald Olson, Walter Wiese, Coleman Nordhausen, and James
Hunnel.

     The Pelican River Watershed District and the City of Detroit
Lakes were very helpful in furnishing background information and the
assistance of some key personnel.  Special recognition is due
Winston C. Larson, of Winston C. Larson and Associates, Consulting
Municipal Engineers, and Dr. T. A. Rogstad, Chairman, Pelican River
Watershed District, who have for years endeavored to resolve the
Lake Sallie problem and are still attacking it with undiminished
enthusiasm, for encouragement and much timely assistance.

     Discharges were provided by the U.S. Geological Survey, St. Paul,
Minnesota.  Charles R. Collier_, District  Chief, William B. Mann IV,
and Thomas Winter of that office also furnished information on ground
water  and water budgets.

     Donald W. Shultz, Chemist, Pacific Northwest Water Laboratory,
EPA, supervised chemical analyses of weed, fish, and sediment
s amp1e s.

     Close estimates of weeds were greatly aided by the excellent
cooperation of Carl Aarness, harvester operator.

     The project was supported by a grant  (16010 DPI) from the Environ-
mental Protection Agency and very fine assistance was furnished by
Drs. Kenneth Malueg and Charles F. Powers, Project Officers.

     The deepest appreciation  is expressed to all the above individuals
and organizations, none of whom gave sparingly.
                                 27

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                               REFERENCES

 1.   Allison,  I.  S.,  "The geology and water resources of northwestern
     Minnesota,"  Minn.  Geol.  Sur. Bull.  No. 22, 245 pp.  (1932)

 2.   American  Public  Health Association, "Standard methods for the examin-
     ation of  water  and wastewater," 12th ed.,  New York, 769 pp.   (1965)

 3.   Bailey,  T. A.,  "Commercial possibilities of dehydrated aquatic plants,"
     Proc. So. Weed  Conf. 18:543-551  (1965)

 4.   Blanchard,  J. L.,  "Aquatic weed harvester operational report," Proc.
     So.  Weed  Conf.  18:477-479  (1965)

 5.   Chang, S. C., and  M. L.  Jackson, "Soil phosphorus fractions in some
     representative  soils," Jour. Soil Sci. 9:109-119  (1957)

 6.   Edmondson, W.  T. ,  "Changes in Lake  Washington following an increase in
     the  nutrient income," Verh. Internat.  Verein. Limnol. 14:167-175   (1961)

 7.   Edmondson, W.  T.,  "Changes in the oxygen deficit of Lake Washington,"
     Verh. Internat.  Verein.  Limnol. 16:153-158  (1966)

 8.   Edmondson, W.  T.,  "Lake eutrophication and water quality management:
     The  Lake  Washington Case," In Water Quality Control, Univ. of Washington
     Press, Seattle,  pp. 139-178  (1968)

 9.   Hasler,  A.  D. ,  "Eutrophication of lakes by domestic drainage," Ecology
     28:383-395   (1947)

10.   Koch, F.  C., and T. L. McMeekin, "A new direct Nesslerization Micro-
     Kjeldahl  method and a modification  of  the Nessler-Fohn reagent for
     ammonia," J. Amer. Chem.  Soc. 46:2066-2069  (1924)

11.   Krawczyk, D. F. , "Analytical techniques for the national eutrophication
     research  program," Fed.  Wat. Poll.  Cont. Admn., Pacific Northwest Water
     Lab, 141  pp.  (1969)

12.   Lange, S. R.,  "The control of aquatic  plants by commercial harvesting,
     processing,  and marketing," Proc. So.  Weed Conf. 18:536-542   (1965)

13.   Larson, W.  C.,  "Spray irrigation for the removal of nutrients in sewage
     treatment plant  effluent as practiced  at Detroit Lakes, Minnesota,"
     Trans. 1960  Seminar:  Algae and Metropolitan Wastes, U. S. DHEW,
     Cincinnati,  Ohio,  pp. 125-129  (1961)

14.   Livermore, D. F.,  "Harvesting underwater weeds," Waterworks Eng.
     107:118-121   (1954)
                                    28

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15.  Minder, L., "Biologisch - chemische untersuchungen in Zurichsee,"
     Rev. d'Hydrologie 3:1-69  (1926)

16.  Minder, L., "Der Zurichsee als eutrophierungsphanomen.  Summarische
     ergebnisse aus funfzig jahren Zurichseeforschung," Geol. Meere
     Binnegewasser 2(2):28-299  (1938)

17.  Minder, L. , "Neuere untersuchungen uber den sauerstoffgehalt und die
     eutrophie  des Zurichsees," Arch. f. Hydrobiol. 40(1):279-301   (1943)

18.  Moyle, J.  B. , "Classification of lake waters upon the basis of hardness,"
     Proc. Minn. Acad. Sci. 13:8-12   (1945a)

19.  Moyle, J.  B. , "Some chemical factors influencing the distribution of
     aquatic plants in Minnesota," Amer. Midi. Nat. 34:402-420   (1945b)

20.  Moyle, J.  B., "Relationships between chemistry of Minnesota surface
     waters and wildlife management," J. Wildl. Mgmt. 20:303-320  (1956)

21.  Olson, Donald, Personal communication (1971, '72)

22.  Peterson,  S. A., "Nutrient dynamics, nutrient budgets, and weed harvest
     as related to the limnology of an artifically enriched lake," Unpub.
     doctoral dissertation, Univ. of North Dakota xvii +  210 pp.  (1971)

23.  Reedstrom, D. C. and R. A. Carlson, "A biological survey of the Pelican
     River watershed, Becker, Clay, and Ottertail Counties," Minnesota
     Dept. Conserv. Spec. Pub. No. 65, 117 pp.   (1969)

24.  Sawyer, Co N., "Fertilization of lakes by agricultural and urban
     drainage," Jour. N.E. Water Works Ass'n. 61:109-127  (1947)

25.  Smith, W.  L., "Plankton, weed growth, primary productivity, and their
     relation to weed harvest in an artificially enriched lake," Unpub.
     doctoral dissertation, Univ. of North Dakota xv + 222pp.   (1972)

26.  Strickland, J. D. H. and T. R. Parsons, "A manual of sea water analysis,"
     Fish. Research Board of Canada, viii + 203 pp.   (1965)

27.  U. S. Department of Health, Education, and Welfare,  "Fertilization and
     algae in Lake Sebasticook, Maine," Fed. W.P.C.A., Tech. Ser. Program,
     R. A. Taft San Engr. Center, Cincinnati, Ohio, 124 pp.  (1966)

28.  Wright, H. E., Jr., "Role of the Wadena Lobe in Wisconsin  glaciation
     of Minnesota," Geol. Soc. Amer. Bull. 73:73-100  (1962)

29.  Yount, J. L. , "Aquatic nutrient reduction-potential  and possible methods,"
     Rep. of Florida Anti-Mosquito Ass'n., (35th Annual Meeting) St. Augustine,
     Florida  (1964)

30.  Yount, J. L. and R. A. Grossman, Jr., "Eutrophication control  by plant
     harvesting," Jour. Water Poll. Cont. Fed., Res. Suppl. 42:R173-R183
     (1970)

                                   29

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FIGURES
   30

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    FROM FOX
      LAKE
                                                VSKRAT
                                                LAKE
                                      0   660  ISZO


                                      SCALE IN FEET


                                     0   250   500


                                     SCALE IN METERS
FIGURE 1. BATHYMETRIC  MAP  OF  LAKE SALLIE,
         MINNESOTA.
                       31

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                            STABILIZATION
                              LAGOON
                                             CITY OF
                                             DETROIT
                                             LAKES
                                        WASTE
                                       TREATMENT
                                        PLANT
SCALE IN METERS
                        FIGURE 2.
      FLOW  ROUTE  OF  WASTEWATER EFFLUENT  FROM
      DETROIT LAKES TO LAKE SALLIE.
                       32

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                                 LAKE
                                 PARK

                                   UDUBON*
                 CLAYEY MORAINE
                 OUTWASH GRAVEL
                                                  ETROIT
                                                  LAKES
                                                  LAKE
                                                 SALLIE
                                                VERGAS
              (a)
                    km
              FERGUS FALLS
              (b)
                  -ALEXANDRIA MORAINIC COMPLEX
              DES MOINES
                 TILL
PELICAN RIVER
 WATERSHED
FERGUS FALLS
"•—MORAINE
FIGURES.  GLACIAL DEPOSITS IN THE PELICAN  RIVER
           WATERSHED (A)TOPOGRAPHIC (B) CROSS-
           SECTIONAL. (REDRAWN FROM ALLISON,  1932)
                          33

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FROM FOX
                                  PELICAN
                                     IVER
     FIGURE 4,  LAKE SALLIE SAMPLING STATIONS
                           34

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FIGURE 5,   TRANSECTS  FOR TOWING OXYGEN PROBE

-------
 LOADING SITE
FROM FOX
  LAKE
                                     PELICAN
                                       RIVER
     FIGURE 6.  WEED HARVEST AREAS IN LAKE SALLIE
                              36

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r  ^
u
LU
   20-
LU
Q_
LJ
     o-
                                                i    ri^
            SEP OCT NOV  DEC  JAN  FEB  MAR  APR  MAY  JUN  JUL AUG SEP
                 1969
1970
      FIGURE 7,   TEMPERATURE VARIATION AT SURFACE AND ID METERS

-------
                                                   SURFACE	
                                                        6m	
                                                       12m	
00
I   ICE COVEfT
                                FIGURE 8,  TEMPERATURE VARIATION WITH DEPTH, 1971

-------
 2-



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18-
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10-
 12-



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 14-
               i       r
APRIL 30    MAY     31     JUNE    30     JULY      31   AUGUST    31
     FIGURE 9,   POSITION AND THICKNESS OF THERMXLINE DURING

                OPEN WATER SEASON, 197L IN LAKE SALLIE
                              39

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                                               I METER DEPTH
                                               3 METER DEPTH
   35
   30H
   25
   20
   15
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                             25305   10  20  31   10  20  30  10  20   31   10  20   31   10  20 30  10   20   31  10  20  30
                             APRIL    MAY        JUNE       JULY       AUGUST    SEPTEMBER  OCTOBER   NOVEMBER
                                 FIGURE ID,   ANNUAL VARIATION IN LIGHT INTENSITY AT 1 AND 3 M,

-------
                     2 JUN 70
                  24 AU6 70
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60-





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FIGURE 11,   SEASONAL CHANGES  IN WAVE LENGTH  PENETRATION
                              41

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60-i
                                             24 JUN 71
50-
40-
30-
 20-
     400
                                                              0.5m
627
                    FIGURE 11,  CONTINUED
                               42

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50-
                                             20 AUQ 71
                                                              0.5m
                                                                .Om
                                     400
                                                           627
                  FIGURE II,   CONTINUED
                             43

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                                              USKRAT
                                                LAKE
                                            >75% SAND
                                                  SAND
FIGURE 12,  DISTRIBUTION OF SAND IN  LAKE SALLIE SEDIMENTS
                           44

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   9.5-1
                      ICE COVER
                             [ICE COVER"
              STATION  I 	    STATION 4
     STATSON 8	
   9.0-
X
Q.
   8.5^
    8.0
    7.5-
    7.0-
              N    D    J    F

             1970
M
N
      1971
        FIGURE 13,  VARIATION IN SURFACE WATER pH AT 3  LAKE SALLIE SITES

-------
10-

9-

8-

7-
 
-------
          ICE COVER
ICE COVER
    BLUE-GREENS
    DIATOMS
    GREENS
                                                      0  '  H  '  D
                                                            1971
FIGURE 15,   MEAN MONTHLY PERCENTAGES OF MAJOR PHYTOPLANKTON GROUPS
            IN SURFACE WATER/ STATION 4

-------
cr
UJ
z
<
co
  10,000;



  5,000-
   500-
    100

  10,000;



  5,000:
   l,000r
   500-
CO
ZD
o

I-
100:
    50-
          1969
          1970
                                       SURF

                                         METER

                                    — 2 METERS

                                    —• 3 METERS
         APR  '  MAY  '  JUN  '  JUL  '  AU6  '  SEP  '  OCT  '
       FIGURE 16,   VARIATION  IN  LIMNETIC PHYTOPLANKTON

                   CONCENTRATION AT DIFFERENT DEPTHS
                            48

-------
IOO,OOO-i
            ICE COVER
                                              HCE COV.
 10,000-
 1,000-
  100-
                                     — SURFACE
                                     — 4 METERS
                                     — 8 METERS
N" D
 1970
             J'F'M'A'M'J'J
A ' S   0   N  D
           1971
                 FIGURE 16,  CONTINUED
                           49

-------
  lO.OOOg
o:
LU
   1,000:
    100:
CO
Z)
o
X
     10=
                      BLUE-GREEN ALGAE

                      GREEN ALGAE
                      DIATOMS
                      ANIMALS
JUL rAUG '  SEP  ' OCT  NOV**MAY   JUN  JUL
                                            V
                                                         SEP  OCT
                   1969
                                        1970
         FIGURE 17,   VARIATION  IN CONCENTRATION OF MAJOR PLANKTON
                     GROUPS IN  SURFACE WATER

-------
  100,000-1
   10,000-
tr
LU
   1,000-
en
;}
o
I
     100-
                                                           IICE cov. I
                                     	 BLUE-GREEN ALGAE

                                     	 GREEN ALGAE

                                          DIATOMS
                                                   s
N
           1970
 1971
        FIGURE 18.  SEASONAL SUCCESSION IN CONCENTRATION OF

                    MAJOR PHYTOPLANKTON GROUPS  IN SURFACE WATER

                    AT STATION 4,
                              51

-------
            \
              V
EXTENT  OF
ROOTED
  VEGETATION
SCIRPUS

POTAMOGETON
  8 RUPPIA
   MYRIOPHYLLUM
                                     U^MUSKRAT
                                          LAKE
FIGURE 19,  AREAS WITH ROOTED VEGETATION
                     52

-------
Ul

OJ
          650-1
          600-
        10



        Q
        uj  500-
        X
o
CD
QC.


S 400-

9

J


>-

H



E 300-
         o
         cc
         a,


         E 200-
         a
         a.

         co
         co

         g 100-
         &
                        1  S '  0

                        1969
                          N
J '  A  '  S

  1970
N
M
J  ' A

 1971
                       FIGURE 20,  GROSS PRIMARY PRODUCTION IN LIMNETIC SURFACE WATER (STATION

-------
           650-,
Ul
-P-
                     AIS'OIN"MIJIJIAIS'OIN"AIMIJIJIAISIOIN
                FIGURE 21,  AVERAGE GROSS PRIMARY PRODUCTION  IN THE  LIMNETIC PHOTIC ZONE (STATION

-------
   600-1
o
  500-
f
1 400-

o


1 300-
   200-
g-  100-
   100-
PO

 6.
   200-
 2 300-
 ©
<


a,

yj
   400-
                                                          0
                                                               N
A
M
                                               1970
 J    A

1971
     FIGURE 22,   NET PRIMARY PRODUCTION AND RESPIRATION RATES IN SURFACE WATER AT STATION 4

-------
*E 600-j
 o
 a>
 •i. 500
 z
 o
 1- 400-
 o
 o
 g SCO-
 IS 200-
 cc
 Q- 100-
 t-
                                                         U-H-lh
10  100-

 o
 I 200-J
   300-
 IT
 a. 400H
 co
 o:
              AISIOIN"MIJIJIAISIOIN"A'MIJIJ  '  A '   s '  o '
                 1969                          1970                               1971
    FIGURE 23.  NET PRIMARY PRODUCTION AND RESPIRATION  RATES WITHIN THE PHOTIC ZONE AT STATION

-------
                  mg C fixed/mVhr
       -100
       0
       m
       o
100
    200
400
600
800
       2-
       4-
       6J
                                 13 JUL 69

                                 15 AUG 69

                                 25 AUG 69
 -100   0   100  200
       I     I	i
mg C  fixed/m3/hr

             400
                                        600
                                         i
                                800
m

2-


4-


6-



8-



10-
                                        2 JUN 70

                                       16 JUL 70

                                       24 AUG 70
                  mg C fixed/mVhr
       0-
       m
       2-
       4-
       6J
                 200
                  i
                    400
                  600
                   I
                          	   30 JUN 71

                          	   20 AUG 7!
                                          SEP  71
FIGURE 24,   VERTICAL VARIATION IN GROSS PRIMARY PRODUCTION
            ON SELECTED DATES AT STATION 4
                        57

-------
00

100-





w80-
jc
\
ro
E
*^X,
T3

E

40-



i-\
! \
! %
I \GROSS.PRIMARY PRODUCTION
I l >*•
' \
1 »
1 '








N-_.

1
I
1
I
H
i
i
i
i
i
i
i
i
tS

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\'








' fa« 	 LAN6LEYS
I t
1 I .
1 I h
, * ! VM/
\ |5 V
\ |t ' f i
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V i /SJ
t 1 /
k
-------
                                                                    50.00
  2O-
JC   -
"-S
ro

E
O
UJ
X
g  "0-
cc

O
o>
E
                 BASED UPON MEAN VALUE WITHIN PHOTIC ZONE
	 BASED UPON SURFACE VALUE
       APRIL
          MAY
JUNE
JULY
AUGUST
SEPTEMBER
OCTOBER
                 FIGURE 26,  PHOTOSYrrmETIC EFFICIENCY AT STATION 4 DURING 1971

-------
TABLES
 60

-------
                                                  TABLE 1
                                MEAN TEMPERATURE AND PRECIPITATION RECORDED
                                        AT DETROIT LAKES, MINNESOTA

1946-1960a

Month
January
February
March
April
May
June
July
August
September
October
November
December
Total
Mean
Temp.
(°0
-15.1
-12.9
- 5.5
4.5
12.2
17.7
21.2
19.7
13.9
7.4
3.1
-11.2
Mean
Precip.
(cm)
1.80
1.73
2.51
5.13
7.59
9.63
9.09
9.53
4.98
3.48
2.49
1.80
59.76
1969b
Mean
Temp.
(°0
-18.3
-10.5
- 8.8
8.1
12.4
13.6
19.1
21,1
14.1
9.5
- 1.7
- 8.9

Precip.
(cm)
4.17
2.01
0.30
2.74
5.61
11.10
2.11
5.97
7.42
4.53
2.69
51.34
1970b
Mean
Temp.
(°C)
-16.5
-13.7
- 8.7
3.8
11.2
18.6
20.8
19.2
14.3
6.6
3,7
-12.4

Precip.
(cm)
0.41
0.66
2.34
7.29
4.63
13.72
3.94
0.69
6.88
5.92
1.07
1.98
49.53
1971b
Mean
Temp.
(°0
-18.7
-11.9
- 6.3
6.9
10.8
18.5
17.5
18.1
14.2
8.6
- 2.2
-11.1

Precip.
(cm)
1.88
2.34
1.83
2.13
4.01
13.44
11.48
6.96
17.07
11.43
3.05
0.64
66.22
1969-1971
Mean
Temp.
<°0
-17.8
-12.0
- 7.9
6.3
11.5
16.9
19,1
19.5
14.2
8.2
- 0.1
-10.8

Precip.
(cm)
2.15
1.67
1.49
4.05
4.75
13.58
8.84
3.25
9.97
8.26
2.27
1.77
62.05
     aModified from D. C. Reedstrom and R. A. Carlson, 1969,  A biological survey of the Pelican
River watershed, Becker, Clay, and Ottertail Counties, Minn.  Dept.  Conserv.  Special Publ.  No.  65,

     bU.S. Dept. of Commerce, Climatological data.

-------
                         TABLE 2

VERTICAL VARIATION IN WATER CHEMISTRY AT STATION 4,  LAKE
  SALLIE, MINNESOTA  (Concentrations, except pH, in ppm)

r
Depth
Date (m)
3,970
10 October 0
2
5
8
11
23 October 0
4
8
12
6 November 0
3
6
9
13 November 0
4
8
19 December 0
2
4
6
8
12
29 December 0
4
8
1971
7 January 0
2
4
pH

8.85
8.80
8.80
8.90
8.90
8.75
8.75
8.75
8.75
8.80
8.80
8.80
8.80
8.85
8.85
8.85
9.00
8.90
8.90
8.90
8.60
8.25
8.90
8.90
8.30

9.00
8.90
8.85
co3
Alk.

40
40
40
36
40
32
32
32
32
36
34
34
34
40
40
40
44
48
48
44
24
8
44
44
12

44
40
40
HC03
Alk.

126
136
136
140
138
142
142
142
142
137
140
140
138
134
134
134
142
140
140
146
178
227
150
146
193

160
154
155
Total
Hardness

166.6
166.6
166.6
186.2
176.4
186.2
186.2
186.2
186.2
186.2
176.4
176.4
176.4
186.2
186.2
186.2
196.0
186.2
186.2
186.2
196.0
225.4
196.0
196.0
196.0

196.0
186.2
186.2
Ca++

58.8
58.8
58.8
58.8
58.8
68.6
58.8
58.8
58.8
58.8
58.8
58.8
58.8
58.8
58.8
58.8
58.8
58.8
58.8
58.8
68.6
78.4
58.8
58.8
68.6

68.6
58.8
58.8
                             62

-------
TABLE 2—Continued


Mq++
107.8
107.8
107.8
107.8
117.6
117.6
127.4
127.4
127.4
127.4
117.6
117.6
117.6
127.4
127.4
127.4
137.2
127.4
127.4
127.4
127.4
147.0
137.2
137.2
127.4
127.4
127.4
127.4
°2
8.62
8.62
8.53
8.53
8.82
10.00
9.90
9.90
9.11
12.40
12.40
12.30
12.20
13.20
13.20
13.20
16.07
14.31
14.31
13.56
9.99
6.47
15.48
14.99
6.66
15.20
15.10
13.10
Ortho
P04
0.18
0.25
0.25
0.12
0.25
0.12
0.18
0.12
0.12
0.12
0.25
0.12
0.12
0
0.11
0.11
0
0
0
0
0
0.06
0.05
0
0
0.18
0.05
0
Total
P04
0.76
1.28
0.76
1.00
1.00
0.62
1.14
0.76
0.76
0.76
0.76
0.50
0.50
0.50
0.36
0.36
0.24
0.12
0.12
0.24
0.24
0.50
0.10
0.24
0.24
0.24
0.24
0.24
NH3-N
0.09
0.10
0.10
0.40
0.11
0.15
0.15
0.12
0.10
0.92
0.97
0.92
0.79
0.48
0.38
0.37
0.25
0.49
0.12
0.20
0.49
0.38
0.27
0.25
0.32
0.23
0.18
0.20
N02-N
0.006
0.004
0.006
0.004
0.006
0.008
0.008
0.006
0,006
0.010
0.008
0.008
0.010
0.012
0.010
0.008
0.008
0.006
0.008
0.006
0.006
0.015
0.008
0.004
0.006
0.006
0.008
0.008
N03-N
0.020
0.008
0,009
0.013
0.011
0.007
0.009
0.009
0.011
0.007
0.009
0.004
0.005
0
0.007
0.004
0.010
0.006
0.010
0.009
0.011
0.020
0.004
0.004
0.009
0.011
0.009
0.009
Temp.
°c
9.0
9.0
9.0
9.0
9.0
9.0
9.0
9.0
9.0
5.5
5.5
5.5
5.5
3.5
3.5
3.5
0
1.0
1.0
1.0
2.0
2.5
1.0
2.0
3.0
1.0
2.0
2.0
          63

-------
TABLE 2—Continued


Depth
Date (m)
6
8
10
12
22 January 0
2
4
6
8
10
6 February 0
2
4
6
8
10
11 February 0
2
6
8
12
14
23 April 0
2
4
8
10
14
30 April 0
2
4
8
7 May 0
2
4
8
28 May 0
4
pH
8.80
8.05
7.90
7,60
8.80
8.80
8.80
8.70
8.10
7.80
8.70
8.80
8.55
8.10
8.40
7.80
8.80
8.75
8.70
7.80
8.20
7.50
8.70
8.70
8.65
8.65
8.60
8.60
8.70
8.65
8.65
8.65
8.70
8.70
8.70
8.70
8.70
8.70
co3
Alk.
36
0
0
0
40
44
40
32
4
0
36
40
28
6
18
0
48
36
32
8
0
0
34
32
34
34
32
32
38
34
34
34
34
34
34
34
32
32
HC03
Alk.
164
220
230
228
156
153
156
168
218
230
170
168
185
225
199
237
156
164
172
200
232
254
157
150
157
157
160
160
152
153
157
157
155
155
155
155
155
155
Total
Hardness
186.2
215.6
225.4
230.3
196.0
196.0
196.0
205.8
235.2
254.8
215.6
215.6
225.4
235.2
225.4
245.0
205.8
205.8
215.6
235.2
254.8
254.8
205.8
205.8
205.8
205.8
205.8
205.8
215.6
215.6
215.6
215.6
210.7
210.7
210.7
210.7
205.8
205.8
Ca++
58.8
78.4
78.4
88.2
68.6
68.6
68.6
68.6
88.2
98.0
68.6
68.6
68.6
78.4
68.6
88.2
68.6
68.6
68.6
78.4
88.2
98.0
68.6
68.6
68.6
68.6
68.6
68.6
88.2
88.2
88.2
88.2
68.6
68.6
68.6
68.6
68.6
68.6
         64

-------
TABLE 2—Continued
. 	
Mg++
127.4
137.2
147.0
142.1
127.4
127.4
127.4
137.2
147.0
156.8
147.0
147.0
156.8
156.8
156.8
156.8
137.2
137.2
147.0
156.8
166.6
156.8
137.2
137.2
137.2
137.2
137.2
137.2
127.4
127.4
127.4
127.4
142.1
142.1
142.1
142.1
137.2
137.2
°2
12.00
5.70
4.20
2.60
14.90
15.10
13.60
11.80
5.90
2.00
13.33
12.84
11.47
6.27
8.82
3.43
14.00
12.50
11.20
6.60
5.00
0
13.90
13.90
13.90
13.90
13.72
13.72
12.25
12.54
12.44
12.44
12.00
12.00
12.00
12.00
11.60
11.80
Ortho
P04
0
0.32
0.12
0.25
0.25
0.18
9.63
0.25
0.18
0.18
0.12
0
0
0.38
0.25
0.25
0.12
0.19
0.25
0.38
0.38
0.25
0.06
0.06
0.12
0.06
0.06
0.12
0
0
0
0.06
0.05
0.05
0
0.05
0
0
Total
P04
0.22
0.24
0.50
0.76
0.38
0.24
0.24
0.38
1.02
0.62
0.38
0.24
0.24
0.64
0.50
0.64
0.10
0.28
0.28
0.76
0.76
1.02
0.30
0.30
0.50
0.30
0.30
0.50
0.24
0.24
0.24
0.36
0.24
0.10
0.10
0.24
0.24
0.10
NH3-N
0.20
0.28
0.30
0.37
-
-
-
-
-
-
0.16
0.16
0.23
0.55
0.40
0.46
0.20
0.22
0.26
0.28
0.32
0.20
0.40
0.31
0.36
0.44
0.28
-
1.15
1.28
1.28
1.41
0.48
0.59
0.43
0.39
0.15
0.19
NO2-N
0.006
0.012
0.008
0.008
0.008
0.012
0.017
0.012
0.030
0.35
0.023
0.026
0.030
0.026
0.028
0.026
0.019
0.024
0.024
0.024
0.028
0.021
0.004
0.008
0.006
0.004
0.004
0.006
0.004
Oc004
0.004
0.004
0.001
0.004
0.004
0.004
0.001
0.004
NO3-N
0.006
0.014
0.014
0.014
-
0
-
-
-
-
0.011
0.008
0.011
0.015
0.011
0.035
0.009
0.004
0.01]
0.050
0.058
0.109
0.004
0
0.002
0.007
0.007
0.005
0.004
0.004
0.004
0.004
0.007
0.004
0.004
0.004
0.007
0.004
Temp.
°C
2.5
2.5
3.0
3.0
1.0
2.0
2.0
3.0
3.0
3.5
0.0
2.0
1.5
2.0
3.0
3.0
1.0
2.0
2.5
3.0
4.0
4.0
7.5
7.0
7.0
7.0
7.0
7.0
7.0
7.5
7.5
7.5
12.0
12.0
11.5
9.5
11.5
10.5
        65

-------
TABLE 2—Continued


Depth
Date (m)
8
12
4 June 0
2
6
10
9 June 0
2
6
8
21 June 0
2
4
8
12
29 June 0
2
4
6
8
10
7 July 0
2
4
8
10
14
14 July 0
2
6
8
10
14
22 July 0
2
4
8
12
PH
8.50
8.40
8.80
8.80
8.60
8.40
8.85
8.85
8.65
8.35
8.75
8.70
8.70
8.20
7.90
8.80
8.80
8.80
8.70
7.80
7.75
8.80
8.80
8.80
8.05
7.80
7.70
8.70
8.70
8.70
7.90
7.50
7.40
8.80
8.75
8.75
8.50
8.30
C03
Alk.
24
16
40
40
28
16
36
38
28
12
32
28
28
4
0
32
36
36
28
0
0
32
32
32
2
0
0
28
28
28
0
0
0
30
28
26
16
10
HCO3
Alk.
165
177
152
152
164
179
154
155
167
184
150
154
157
192
202
148
144
144
157
202
206
145
145
144
187
200
205
136
135
138
176
195
200
135
136
137
152
160
Total
Hardness
225.4
225.4
210.7
205.8
196.0
196.0
186.2
196.0
196.0
196.0
176.4
176.4
176.4
196.0
196.0
186.2
181.3
186.2
186.2
205.8
200.9
176.4
176.4
176.4
186.2
200.9
200.9
176.4
176.4
176.4
186.2
200.9
205.8
176.4
176.4
176.4
176.4
181.3
Ca++
68.6
78.4
83.3
73.5
73.5
68.6
78.4
73.5
78.4
68.6
68.6
68.6
68.6
78.4
83.3
78.4
63.7
68.6
68.6
78.4
78.4
63.7
58.8
58.8
68.6
73.5
73.5
58.8
63.7
63.7
68.6
74.4
83.3
63.7
63.7
68.6
68.6
68.6
       66

-------
TABLE 2—Continued


Mg++
156.8
147.0
127.4
132.3
122.5
127.4
107.8
122.5
117.6
127.4
107.8
107.8
107.8
117.6
112.7
107.8
117.6
117.6
117.6
127.4
122.5
112.7
117.6
117.6
117.6
127.4
127.4
117.6
112.7
112.7
117.6
126.5
122.5
112.7
112.7
112.7
112.7
112.7
°2
9.20
7.20
11.10
11.70
8.80
4.80
10.00
10.20
6.20
3.40
8.90
8.60
8.00
1.40
0.10
9.70
9.60
9.60
5.90
0.20
0.10
8.10
8.20
7-70
1.40
0.20
0
7.52
7.52
6.53
0.40
0
0
8.89
8.48
7.88
3.23
1.21
Ortho
P04
0
0.05
0
0
0
0
0
0
0
0
0
0.12
0.05
0
0.12
0.05
0
0.12
0.05
0.19
0.12
0.12
0
0.12
0.18
0.32
0.32
0.12
0.12
0.12
0.25
0.51
0.77
0
0
0
0.11
0.11
Total
P04
0.24
0.64
0.24
0.10
0.24
0.50
0.24
0.36
0.24
0.24
0.36
0.24
0.50
0.24
0.24
0.24
0.24
0.12
0.24
0.24
0.50
0.24
0.50
0.36
0.36
0.50
0.50
0.50
0.64
0.50
0.50
1.02
1.16
4.86
0.36
0.36
0.50
0.50
NH3-N
0.27
0.27
0.38
0.27
0.25
0.33
0.32
0.33
0.40
0.40
0.36
0.36
0.31
0.48
1.18
0.28
0.28
0.31
0.33
0.74
0.82
0.36
0.37
0.39
0.77
1.08
1.33
0.33
0.37
0.46
1.11
2.07
2.60
0.32
0.32
0.36
0.74
0.81
NO2-N
0.004
0.004
0.004
0.004
0.001
0.004
0.001
0
0.001
0.004
0.004
0
0
0
0
0.004
0.004
0.004
0.001
0.004
0.001
0.001
0.001
0.001
0.001
0.017
0.004
0.004
0.001
0
0.001
0
0
0.001
0.004
0.001
0.004
0.006
NO3-N
0.004
0.006
0.004
0.004
0.007
0.004
0.005
0.006
0.005
0
0.004
0.008
0.008
0.012
0.012
0.002
0.002
0.002
0.007
0.002
0.005
0.007
0.009
0.007
0.007
0.008
0.004
0.004
0.005
0.006
0.003
0.004
0.004
0.005
0.004
0.005
0,002
0.002
Temp.
°C
10.0
10.0
18.0
15.0
13.0
13.0
17.0
17.0
14.0
14.0
22.5
22.5
22.0
16.0
15.5
22.0
22.0
22.0
20.0
16.0
16.0
23.0
23.0
22.5
19.0
18.0+
17.0
21.0
21.0
21.0
18.5
17.0
17.0
21.0
21.0
21.0
20.0
20.0
         67

-------
TABLE 2—Continued


Depth
Date (m)
14
29 July 0
2
4
8
14
12 August 0
2
4
8
14
25 August 0
6
14
4 September 0
2
4
8
14
12 September 0
8
14
17 September 0
8
14
24 September 0
2
8
14
1 October 0
8
14
8 October 0
4
8
14
15 October 0
8
ph
8.10
8.70
8.65
8.65
8.65
8.65
8.90
8.90
8.90
8.60
8.25
8.70
8.70
8.05
8.85
8.85
8.80
8.70
8.55
8.70
8.70
8.50
8.70
8.70
8.70
8.90
8.85
8.70
8.70
8.70
8.50
8.30
8.55
8.55
8.55
8.50
8.80
8.80
C03
Alk.
4
20
20
20
20
20
36
34
32
18
6
26
26
2
30
30
28
24
16
24
24
16
28
28
26
36
34
26
26
28
14
4
16
16
16
14
34
34
HCO3
Alk.
166
142
142
141
143
144
124
127
127
147
165
135
133
167
129
129
130
136
150
137
138
148
133
132
139
129
131
139
141
137
151
156
146
146
147
149
131
131
Total
Hardness
181.3
176.4
176.4
176.4
176.4
176.4
166.6
166.6
166.6
176.4
186.2
176.4
176.4
181.2
176.4
176.4
176.4
176.4
181.3
176.4
176.4
176.4
181.3
176.4
176.4
181.3
181.3
181.3
186.2
181.3
181.3
181.3
186.2
181.3
181.3
176.4
186.2
186.2
Ca++
68.6
68.6
68.6
68.6
68.6
63.7
58.8
58.8
58.8
58.8
68.6
63.7
58.8
68.6
63.7
58.8
58.8
58.8
58.8
58.8
58.8
63.7
53.9
58.8
58.8
68.6
68.6
68.6
68.6
73.5
73.5
73.5
73.5
68.6
68.6
68.6
68.6
68.6
      68

-------
TABLE 2—Continued


Mg++
112.7
107.8
107.8
107.8
107.8
112.7
107.8
107.8
107.8
117.6
117.6
112.7
117.6
112.6
112.7
117.6
117.6
117.6
122.5
117.6
117.6
112.7
127.4
117.6
117.6
112.7
112.7
112.7
117.6
107.8
107.8
107.8
112.7
112.7
112.7
107.8
117 .6
117.6


°2
0.20
7.33
7.33
7.23
7.13
7.13
8.90
8.80
8.80
3.30
0.20
6.60
6.40
0
8.12
7.92
7.72
6.14
2.48
6.70
6.60
3.70
7.80
7.70
6.00
10.60
10.00
6.80
7.10
9.50
5.60
2.70
9.29
9.29
9.09
8.99
11.40
10.30


Ortho
P04
0.11
0
0
0
0
0
0
0
0
0.05
0.52
0.11
0.11
0.60
0.25
0.05
0.25
0.14
0.32
0
0.19
0.26
0.12
0.12
0.25
0.09
0.09
0.09
0.12
0.05
0.05
0.36
0.12
0.12
0.12
0
0.12
0.05


Total
P04
0.50
0.36
0.50
0.50
0.50
0.50
0.50
0.36
0.50
0.50
0.64
0.50
0.50
0.92
0.92
0.64
0.92
0.64
0.64
0.59
0.64
0.52
0.64
0.78
0.92
0.64
0.64
0.64
0.92
0.64
0.78
0.64
0.64
0.64
0.64
0.52
0.28
0.50


NH3-N
1.00
0.31
0.33
0.33
0.31
0.31
0.15
0.25
0.22
0.56
0.95
0.54
0.54
1.69
0.32
0.33
0.38
0.45
0.94
0.42
0.43
0.67
0.26
0.39
0.50
0.01
0.01
0.01
0.01
0.18
0.35
0.47-
0.23
0.25
0.25
0.19
0.13
0.13


N02-N
0.006
0
0.001
0
0.001
0.001
0
0
0
0.004
0.004
0.004
0.002
0
0.002
0.004
0
0.003
0.003
0.005
0.004
0.006
0.004
0.004
0.004
0.002
0.002
0.002
0.004
0.005
0.004
0.004
0.005
0.004
0.004
0.004
0.004
0.002


NO3-N
0
0.007
0.003
0.004
0.005
0.005
0.012
0.21
0.017
0.024
0.015
0.017
0.015
0.012
0.019
0.017
0.021
0.025
0.018
0.005
0.006
0.011
0.011
0.008
0.008
0.017
0.013
0.019
0.020
0.020
0.026
0.033
0.012
0.013
0.013
0.013
0.013
0.015


Temp.
°C
20.0
18.0
18.0
18.0
18.0
18.0
20.5
20.5
20.5
19.0
18.0
20.0
20.0
19.0
21.0
21.0
21.0
20.0
20.0
19.0
19.0
19.0
17.0
17.0
17.0
15.0
14.5
14.0
14.0
17.0
15.0
14.0
12.0
12.0
12.0
12.0
10.0
10.0
         69

-------
TABLE 2—Continued


Depth
Date (m)
14
22 October 0
5
10
29 October 0
6
13
12 November 0
4
8
12
11 December 0
5
10
22 December 0
5
10
14
31 December 0
5
10
14
PH
8.75
8.80
8.80
8.55
8.60
8.60
8.60
8.15
8.55
8.25
7.20
8.65
8.50
7.55
8.40
8.30
7.60
7.50
8.40
8.20
7.50
7.50
C03
Alk.
32
34
34
20
20
24
24
6
20
8
0
28
20
0
16
16
0
0
18
12
0
0
HCO3
Alk.
132
129
129
144
146
140
140
162
149
156
158
156
164
192
177
182
196
205
187
192
202
202
Total
Hardness
186.2
176.4
176.4
176.4
186.2
186.2
186.2
196.0
196.0
186.2
205.8
215.6
215.6
215.6
225.4
207.7
205.8
215.6
225.4
215.6
205.8
225.4
Ca++
68.6
58.8
58.8
68.6
68.6
68.6
er ,6
68.6
68.6
78.4
68.6
78.4
78.4
78.4
88.2
88.2
78.4
88.2
88.2
88.2
88.2
88.2
       70

-------
TABLE 2—Continued


Mg++
117.6
117.6
117.6
117.6
117.6
117.6
117.6
127.4
127.4
107.8
137.2
137.2
137.2
137.2
137.2
119.5
127.4
127.4
137.2
127.4
117.6
137.2
°2
10.20
12.90'
12.40
6.80
9.40
9.40
9.30
13.80
13.30
11.80
5.20
14,80
13.20
1.80
14.40
12.80
1.00
0.60
13.00
11.80
0.80
0.40
Ortho
P04
0
0.05
0
0
0
0.05
0
0
0.12
0.09
0.12
0.19
0.19
0.12
0.01
0.01
0
0
0.25
0.25
0.12
0.12
Total
P04
0.50
0.24
0.24
0.50
0.38
0.50
0.38
0.38
0.66
0.56
0.50
0.38
0.38
0.24
0.02
0.01
0.01
0.01
0.24
0.50
0.38
0.38
NH3-N
0.13
0.11
0.12
0.12
0.12
0.16
0.21
0.15
0.13
0.15
0.15
0.06
0.09
0.15
0.09
0.15
0.30
0.38
0.22
0.24
0.32
0.46
N02-N
0.002
0.004
0.004
0.004
0
0.006
0.004
0.004
0.004
0.004
0.004
0.004
0.004
0.006
0.010
0.006
0.012
0.006
0.008
0.006
0
0
N03-N
0.013
0.014
0.011
0.014
0.013
0.007
0.009
0.011
0.011
0.011
0.011
0.013
0.030
0.018
0.025
0.051
0.018
0.011
0.039
0.050
0.021
0.015
Temp
°C
10.0
12.0
11.0
10.5
9.0
9.0
9.0
2.0
2.0
2.0
3.0
2.0
2.5
3.5
1.5
2.0
3.5
4.0
1.5
2.0
3.5
4.0
         71

-------
                                   TABLE  3

NITROGEN,  CARBON,  AND PHOSPHORUS CONCENTRATION IN SEDIMENTS COLLECTED FROM
         SHALLOW3 AND DEEPb WATER AREAS  OF  LAKE SALLIE, MINNESOTA

Date
1968
September 28
October 19

November 2

November 16

1969
February 7

April 26

June 6

August 17




Stations
1,
3,
1,
3,
1,
3,
1,
4,

1,
3
1,
3,
1,
4,
1,
3,
2, 12
4
2, 8,
5, 6,
8, 9,
4, 5,
2, 7
5, 6

2, 8,

2, 8,
4, 5,
2, 8,
5, 6,
2, 8,
4
9, 12
10, 11
12
6, 10, 11



9

9, 12
6, 10, 11
9, 12
10, 11
12



H2O Sol. P
mg/kg


10




10
30
20
45
13
34
13
27
• •
• •
.20
• •
.
• •

.40
.40
.54
.82
.52
.66
.17
.58

Total P
g/kg
0.72
1.17
0.43
1.41
0.37
1.49
0.80
1.42

0.27
1.43
0.30
1.25
0.32
1.35
0.27
0.77

Component
Ca-P Al-P
mg/kg
125.
22.
•
175.
•
f
•

136.
407.
150.
349.
206.
391.
125.
295.
90 0.09
80 0.14
. .
60 0.08
. .
• • •
. .

00 0.19
00 0.20
00 0.03
20 0.07
50 0.04
30 0.10
67 . .
00 . .

Fe-P
6.93
14.30
• •
1.96
• •
. .
• •

0.51
9.51
3.66
6.17
3.56
9.04
3,14
6.19

Total N
0.64
2.40
0.37
1.40
0.37
1.43
0.85
1.40

0.08
• •
0.18
1.25
0.47
1.51
0.22
0.85

Carbon
5.16
13.65
4.54
14.86
3.85
15.01
9.33
14.73

4.29
• •
4.49
16.97
5.21
15.01
2.20
9.88

-------
                                                  TABLE  3—Continued
UJ

Date
September 28

November 15

1970
January 25

May 22

July 10
Stations
1,
4,
1,
3,

1,
4
1,
4
1,
2, 8, 9
5, 6
2, 12
4

8, 9, 12

9, 12

8, 9, 12


H20 Sol. P
mg/kg
6.
49.
12.
26.

9.
16.
7.
52.
11.
89
90
00
35

70
70
32
40
91


Total P
g/kg
0.
1.
0.
0.

0.
0.
0.
1.
0.
23
35
25
90

23
70
25
46
31

Component
Ca-P Al-P
mg/kg
102.
407.
124.
290.

144.
200.
175.
492.
128.
18 . .
33 . .
33 . .
00 . .

75 . .
00 . .
33 . .
00 . .
15 . .
• • •

Fe-P
0.86
8.94
2.23
5.94

1.29
6.38
2.75
• •
2.64

Total N
%
0.40
1.42
0.27
0.86

0.20
0.80
0.20
1.40
0.25

Carbon
%
2,19
15.16
2.47
8.90

2.91
9.88
1.77
15.30
2.69
          aUpper row of values per  each date.




           Lover row of values per  each date.

-------
                                                          TABLE  4

                                ACID-SOLUBLE PHOSPHORUS  (AS  PO4~P)  OF AIR DRIED  SEDIMENTS
                                         FROM LAKE SALLIE, MINNESOTA, EXPRESSED AS
                                              GRAMS PER KILOGRAM OF SEDIMENTS
—i
-O




7 November 1970
19 December 1970
18 March 1971
8 May 1971
25 June 1971
21 July 1971
30 October 1971
10 December 1971
31 December 1971
1

0.5
0.37
-
0.50
0.14
0.45
1.33
0.19
-
-
3 4

9.0 16.5
1.30 1.24
1.22
-
1.63
1.47
1.28 1.75
0.83
-
1.18
Station
678
Depth (m)
7.5 1.0 0.5
0.51 0.29
0.24
0.34
1.57 - 0.15
1.23 0.30 0.16
1.16 0.35 1.57
0.24
0.19
_ _ _
9

0.5
0.28
0.23
-
0.30
0.29
0.42
0.30
0.26
-
12

0.3
0.31
0.42
0.27
0.38
0.26
0.29
0.18
0.30
-
21

0.3
0.33
0.41
0.39
0.31
0.16
0.21
0.33
0.52
-

-------
                        TABLE 5

TOTAL KJELDAHL  NITROGEN, AS PERCENTAGE  OF DRY WEIGHT
        OF SEDIMENTS, LAKE SALLIE, MINNESOTA



Date
7 November 1970
19 December 1970
18 March 1971
8 May 1971
25 June 1971
21 July 1971
30 October 1971
10 December 1971
31 December 1971
1

0.5
0.29
-
0.13
0.06
0.36
0.88
0.09
-
-
3 4

9.0 16.5
1.15 1.98
1.23
-
1.30
0.85
1.13 0.80
0.48
-
1.07
Station
678
Depth (m)
7.5 1.0 0.5
0.13 0.33
0.18
0.17
1.28 - 0.10
1.38 0.15 0.13
2.00 0.17 0.55
0.50
0.11
- - -
9

0.5
0.09
0.07
-
0.08
0.08
0.12
0.10
0.11
-
12

0.3
0.13
0.21
0.11
0.11
0.08
0.08
0.08
0.09
-
21

0.3
0.11
0.17
0.26
0.12
0.11
0.10
0.11
0.11
-

-------
                                                        TABLE  6

                              CONCENTRATION OF CERTAIN  ELEMENTS  IN VARIOUS AQUATIC PLANTS
                                    FROM LAKE  SALLIE, MINNESOTA, SEPTEMBER 16, 1968
                           Plant
                           Part
                            1/3                                Concentration
                             


-------
                                         TABLE 6 —Continued



Plant Description
Potamogeton


Microcystis
Periphyton
richardsonii


scum
removed
from Vallisneria
Plant
Part
1/3
Q)
a T3 s ' • '
Oi -r-l O
P S >J p N C H
x 0.33 2.8 27.9 3.7 45
x 0.31 2.8 27.3 3.7 44
x 0.34 2.5 25.7 3.2 44
N.A.a 0.72 8.1 43.0 6.2 3

N.A. 0.46 2.7 22.9 3.8 46
Concentration

Ca
.0
.0
.0
.9

.0

Mg
3.2
3.2
2.7
2.0

3.7

Na
0.70
0.80
1.10
0.60

0.36

K Co
5.0 0.100
5.5 0.009
9.0 0.009
3.5 0.018

1.5 0.022
mg/g
Cu
0.015
0.024
0.020
0.023

0.023

Fe
0.870
0.940
1.040
0.780

1.06

Mn
0.441
0.451
0.270
0.223

0.510

Mo
<0.065
<0.065
<0.065
<0.065


-------
00
                                                          TABLE 7

                                       CHEMICAL ANALYSIS OF AQUATIC MACROPHYTES FROM
                                         SELECTED AREAS IN LAKE SALLIE, MINNESOTA

Date
12 July 1971
20 July 1971
27 July 1971
30 July 1971
5 August 1971
10 August 1971
10 August 1971
16 August 1971
16 August 1971
16 August 1971
16 August 1971
Sample
Transect 3-1
Transect 5-2
Area 3
Transect 1-1
Area 6
Transect U-l
Transect 5-3
Transect 6-1
Transect 6-1
Transect 6-1
Transect 6-1
Remarks
Almost entirely Potamogeton pectinatus
Mixture of Ruppia maritiuia and
P. pectinatus
From 0.283 TO. sample
Mixture of Myriophyllum exalbescens
and P. pectinatus
From 0.283 m^ sample
Mixture of M. exalbescens and
P. pectinatus
Mixture of M. exaTbescens and
P. pectinatus
0-15 m from Pelican R. , mostly
M. exalbescens
30-^5 m from Pelican R., mostly
M. exal~bescens
75-90 m from Pelican R. ,
M. exalbescens and P. pectinatus
90-105 m from Pelican R., mostly
P. pectinatus
Total
C
g/kg
336
311
29^
286
250
305
315
307
305
328
312
Total
N
g/kg
18.3
23.7
21.0
28.7
2^.0
23.7
21.3
25.3
25.0
28.3
25.3
Total
P
g/kg
2.25
2.60
2.135
2,lh
2.5^
2.295
2.165
2.515
3.02
2.50
2.683

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                                                  TABLE 8

                           PRIMARY PRODUCTIVITY OF SUBMERGED VASCULAR PLANTS AND
                                 ASSOCIATED PLANKTON, LAKE SALLIE, MINNESOTA
Date
12 August 1970

19 August 1971
20 August 1971


5 September 1971




Location Time
Ac 1100-1145
1145-1600
Bd 2230-0800
Bd 1100-1500
1500-2030
2030-1130
Ce 0715-0915
0915-1215
1215-1415
1415-1615
1615-1815

Totala
1187
587
- 375
713
250
- 411
238
475
119
475
0
Net
Production
Rooted Plank-
Plants21 tona
780
84
-375
475
216
-388
119
158
-119
237
0
407
503
0
238
43
- 24
119
317
238
238
0
Rooted
Plants13 Planktonb
_
-
-6.0
7.6
3.5
-6.2
3.7
5.0
3.7
7.4
0
_
-
0
68.0
12.3
- 6.9
92.2
245.7
184.5
184.5
0
10 September 1971
1700-1900
- 119
-119
- 41.9

-------
                                                     TABLE 8—Continued
Net Production
Date Location Time
11 September 1971 Df 0700-0900
0900-1200
1200-1530
Totala
178
911
950
Rooted
Plantsa
0
594
679
Plank-
tona
178
317
271
Rooted
Plantsb
0
15.2
17.4
Plankton
62.7
111.6
95.4
00
o
      amg C/m3/hr.

      bmg C/g dry weight/hr.

      C250 m NW of Station 1.  Enclosed M. exalbescens.  Depth 1 m.

      dOn weed harvest transect  5-3.  Enclosed M. exalbescens  (19.0 g dry wt) and mixture of
P. pectinatus and R. maritima  (43.5 g combined dry wt) .  Dominant algae were M.  aeruginosa,
A. spiroides and Lyngbya sp.  (17.5 mg/1 dry wt).  Depth  1 m.

      e25 m NW of Station 1.  Enclosed M. exalbescens  (31.9 g dry wt).  Dominant alga was
O_. curviceps (12.9 mg/1 dry wt) .  Depth 0.5 m.

      fon weed harvest transect  3-1.  Enclosed M. exalbescens  (22.7 g dry wt),  R. maritima
(9.0 g dry wt) , and P_. pectinatus  (7.3 g dry wt) .  Dominant alga was A_. spiroides  (14.2 mg/1
dry wt).   Depth 1.1 m.

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                                                      TABLE 9

                   WATER AND NITROGEN AND PHOSPHORUS BUDGETS IN LAKE SALLIE   1968-69 TO 1970-71
                                                    WATER YEAR


A.





B.




C.
D.



E.






In Lake Sallie
Water
Weeds
Fish
Sediment
Total
Input
Pelican R.
Fox Lake
Monson L.
Total
Outflow
Net Gain
or Loss
(B-C) to
Lake
Removed by
Harvest
Fish
Weeds
Total
1968-69
Total Total Water Total
N P Flow N
kg kg m xlC)6 kg

24,740 2,270* - 5,070
- - - 8,149**
7,210 1,980 - 4,270
1,014 95 - 748
32,494 4,345 - 21,412

11,360 10,020 18.96 5,590
200 80 0.78 180
90 20 0.48 80
11,650 10,140 20.22 5,850
9,720 5,810 22.71 2,640
1,930 4,330 -2.49 3,210





1,590
- - - 721
- - - 2,311
1969-70
Total Water
P Plow
kg m3x!06

9,690
1,038**
1,220
73
12,415

7,060 16.77
310 0.66
100 0.41
7,470 17.84
2,510 19.08
4,960 -1.24





406
100
506

Total
N
kg

21,231
2,810
11,594
738
36,729

10,568
393
217
11,178
7,217
3,961





786
248
1,034
1970-71
Total
P
kg

16,513
358
3,152
89
20,112

15,169
305
169
15,643
7,758
7,885





207
26
233

Water
Flow
m3x!06

-
-
-
-
—

16.88
0.62
0.35
17.85
20.81
-2.96





-
-

* Soluble P
**Approximation from
1971 standing crop data and 1970 harvest.

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APPENDIX
 82

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             LIST OF PLANKTERS OBSERVED 1968-71


                          Bacteria


Division Schizophyta


      Class Schizomycetes


            Sphaerotilus natans Kutz.
Division Chlorophyta


      Class Chlorophyceae


            Order Volvocales
                  Chlamydomonas sp. Ehr.
                  Eudorina elegans Ehr.
                  Gonium formosum Pasch
                  Pandorina morum  (Mull.)  Bory
                  Pleodorina californica Shaw
                  Volvox globator L.
            Order Tetrasporales

                  Elakatothrix gelatinosa Wille
                  Ererella bornhomensis Conrad.
                  Gloeocystis gigas (Kutz.)  Lag.
                  Gloeocystis major Ger.  ex Lem.
                  Gloeocystis planetonica (W.  and W.)  Lem.
                  Sphaerocystis Schroeteri Chod.
            Order Ulotrichales

                  Stichococcus bacillaris Naeg.
                              83

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Order Chlorococcales

      Actinastrum gracillimum Lag.
      Ankistrodesmus falcatus (Corda) Ralfs
      Characium gracilipes Lamb.
      Characium limneticus Lem.
      Chlorella ellipsoidea Gern.
      Chlorella vulgaris Beyern.
      Closteriopsis longissima Lemm.
      Coelastrum microporum Naeg.
      Crucigenia fenestrata Sch.
      Crucigenia irregularis Wille
      Crucigenia Lauterbornii Sch.
      Crucigenia quadrata Mor.
      Crucigenia rectangularis (A. Braun) Gay
      Dictyosphaerium Ehrenbergianum Naeg.
      Dictyosphaerium pulchellum Wood
      Kirchneriella obesa (W. West) Schmid.
      Lagerheimia ciliata G. M.  Sm.
      Lagerheimia citriformis (Snow) G. M. Sm.
      Micractinium pusillum Fres.
      Nephrocytium sp. Naeg.
      Oocystis sp. Naeg.
      Oocystis parva W. and W.
      Pediastrum Boryanum (Turp.) Meneg.
      Pediastrum duplex Meyen
      Pediastrum simplex (Meyen)  Lem.
      Planktosphaeria gelatinosa G. M. Sm.
      Quadrigula lacustris  (Chod.) G. M. Sm.
      Scenedesmus arcuatus Lem.
      Scenedesmus bijuga (Turp.)  Lag.
      Scenedesmus dimorphus  (Turp.) Kutz.
      Scenedesmus guadricauda Chod.
      Scenedesmus guadricauda var. longispina  (Chod.)
           G. M. Sm.
      Scenedesmus guadricauda var. maxima W. and W.
      Schroderia Judayi G.  M. Sm.
      Selenastrurn gracile Reinsch.
      Tetradesmus wisconsinense G. M. Sm.
      Tetraedron regulare Kutz.
      Tetraedron arthrodesmiforme  (G. S. West) Wolo.
      Tetraedron pentaedricum W.  and W.
      Tetraedron sp. Kutz.
      Tetrallantos Lagerheimii Teil.
Order Zygnematales

      Closterium moniliforme (Bory) Ehr.
                   84

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                  Cosmarium sp. Breb.
                  Staurastrum paradoxum Meyen
                  Mougeotia sp. (C. A. Ag.) Wittr.
Division Chrysophyta


      Class Xanthophyceae


            Order Heterococcales

                  Ophiocytium capitatum Woll.


      Class Chrysophyceae


            Order Chrysomonadales

                  Dinobryon divergens Imh.


      Class Bacillariophyceae


            Order Centrales

                  Melosira granulata (Ehr.) Ralfs
                  Stephanodi scus astraea  (Ehr.) Grun.
                  Stephano discus astraea var. minutula (Kutz.)  Grun


            Order Pennales

                  Amphiprora sp. Ehr.
                  Asterionella formosa Hass.
                  Cocconeis pediculus Ehr.
                  Cocconeis scutellum Ehr.
                  Cymatopleura solea (Breb.) W. Sm.
                  Cymbella cistula (Hemp.) Grun.
                  Cymbella lanceolata (Ehr.) v. Heur.
                  Cymbella prostata  (Berk.) Cl.
                  Cymbella tumida (Breb.)  v. Heur.
                  Cymbella sp.  Ag.
                  Diatoma sp.  DeCand.
                  Epithemia sorex Kutz.
                  Epithemia sp.  Breb.
                  Epithemia turgida  (Ehr.) Kutz.
                               85

-------
                  Epithemia zebra (Ehr.)  Kutz.
                  Eunotia sp.  Ehr.
                  Fragillaria capucina Desm.
                  Fragillaria crotonensis Kitt.
                  Gomphonema acuminatum Ehr.
                  Gomphonema sp. Hust.
                  Gomphonema lanceolatum Ehr.
                  Gomphonema olivaceum (Lyng.) Kutz.
                  Gomphonema parvulum  (Kutz.)
                  Navicula cuspidata Kutz.
                  Navicula sp.  Bory
                  Nitzschia amphibia Grun.
                  Nitzschia sigmoidea  (Ehr.) W. Sm.
                  Nitzschia sp.  Hass.
                  Rhopalodia sp. 0.  Mull.
                  Stauroneis sp. Ehr.
                  Surirella sp.  Turp.
                  Synedra rumpens Kutz.
                  Synedra ulna  (Nitzsch.) Ehr.
                  Synedra sp.  Ehr.
Division Euglenophyta
            Order Euglenales
                  Euglena sp.  Ehr.
                  Phacus sp.  Duj.
                  Trachelomonas sp.  Ehr.
Division Pyrrophyta


      Class Dinophyceae
            Order Peridiniales

                  Ceratium hirudinella (O.  P.  Mull.)  Duj
                  Glenodinium berolinense (Lem.)  Lindem.
                  Peridinium sp.  Ehr.
      Class Cryptophyceae


            Cryptomonas  sp.  Ehr.




                               86

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Division Cyanophyta


      Class Myxophyceae
            Order Chroococcales

                  Aphanocapsa sp. Naeg.
                  Aphanothece nidulans Naeg.
                  Chroococcus cispersus  (Keissl.) Lem.
                  Chroococcus limneticus Lem.
                  Coelosphaerium dubiurn Grun.
                  Coelosphaerium Kutzingianum Naeg.
                  Coelosphaerium Naegelianum Ung.
                  Dactylococcopsis Smithii Chod. and Chod,
                  Gomphosphaeria aponina Kutz.
                  Marssoniella elegans Lem.
                  Merismopedia punctata Meyen
                  Microcystis aeruginosa Kutz.
                  Microcystis flos-aquae  (Wittr.) Kirch.
            Order Hormogonales

                  Anabaena sp. Bory
                  Anabaena circinalis  (Har.) Rab.
                  Anabaena spiroides Kleb.
                  Aphanizomenon flos-aquae  (L.) Ralfs
                  Gleotrichia natans  (Hed.) Rab.
                  Lyngbya sp. C. A. Ag.
                  Oscillatoria sp. Vauch.
                  Oscillatoria curviceps C. A. Ag.
                  Oscillatoria limosa  (Roth) C. A. Ag.
                  Oscillatoria princeps Vauch.
                  Phormidium sp. Kutz.
                  Spirulina major Kutz.
                           Animals
Phylum Protozoa


      Class Sarcodina


            Order Testacea
                  £ejvt£0pyxis aculeata  (Ehr.) Stein
                  Difflugia sp. Lecl.
                  Difflugia lebes Pen.
                                87

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            Order Heliozoa

                  Actinosphaerium sp. Stein
      Class Ciliata
            Order Holotricha

                  Coleps sp. Nitz.
                  Cyclidium sp.
                  Didinium sp. Stein
                  Enchelys sp.
                  Frontonia sp. Ehr.
                  Lacrymaria sp. Ehr.
                  Prorodon sp. Ehr.
                  Saprophilus sp. Stokes
                  Trachelophullum sp.  Clap, and Lach


            Order Spirotricha

                  Caenomorpha sp.
                  Codonella sp. Haeck.
                  Euplotes sp. Ehr.
                  Halteria sp. Duj.
                  Oxytricha sp. Ehr.
                  Strombidium sp. Clap,  and Lach.
                  Stronibilidium sp.  Schew.
                  Stylonchia sp. Ehr.


            Order Peritricha

                  Epistylis sp. Ehr.
                  Thuricola sp.
                  Vaginicola sp. Lam.
                  Vorticella sp. L.
            Order Suctoria

                  Acineta sp. Ehr.
                  Tokophyra sp.  Buts.
Phylum Nematoda


      Nematode sp.

-------
Phylum Gastrotricha


      Class Chaetonotoidea


            Chaetonotus sp. Ehr.


Phylum Rotifera


      Class Bdelloidea


            Order Bdelloida

                  Philodina sp. Ehr.


      Class Monogononta


            Order Ploima
                  Anuraeopsis sp. Laut.
                  Asplanchna priodonta Gosse
                  Brachionus sp. Pallas
                  Brachionus calyciflorus Ahl.
                  Cephalodella auriculata Bory de St.  Vincent
                  Colurella sp. Bory do St.  Vincent
                  Euchlanis sp. Ehr.
                  Keratella cochlearis (Gosse)
                  Keratella quadrata (Mull.)
                  Lecane sp. Nitz.
                  Monostyla sp. Ehr.
                  Polyarthra euryptera (Wierz.)
                  Polyarthra vulgaris Carl.
                  Synchaeta pectinata Ehr.
                  Trichocerca multicrinis Kell.
                  Trichocerca similis Ehr.
            Order Flosculariaceae

                  Conochilus sp. Hlava
                  Filinia longiseta (Ehr.)
                  Sinantherina socialis (L.)
                               89

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Phylum Tardigrada
            Order Eutardigrada

                  Macrobiotus sp. Schultze
Phylum Arthropoda
      Class Arachnida
            Order Hydracarina

                  Larval mites
      Class Crustacea
            Order Cladocera
                  Alona affinis (Ley.)
                  Alona monocantha Sars
                  Bosmina longirostris (O. F. Mull.)
                  Ceriodaphnia sphaericus (O. F. Mull.)
                  Daphnia longiremis Sars
                  Simocephalus sp. Sch0d.
            Order Podocopa

                  Ostracod sp.


            Order Eucopepoda

                  Cyclops sp. O. F. Mull
                  Diaptomus sp. Westw.
                  Nauplii


                        Miscellaneous
Division Chlorophyta


      Volvocalean spores
                               90

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      Division  Eumycophyta







             Fungal spores







      Division  Tracheophyta







             Pollen grains







      Phylum Rotifera







             Rotifer eggs







      Phylum Annelida







             Class Oligochaeta







                   Aeolosoma sp.  (eggs)







      Phylum Arthropoda







             Class Crus_tacea







                   Order Cladocera




                         Ephippia
frU.S. GOVERNMENT PRINTING OFFICE: 1973-540-309/44 1-3    91

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  SELECTED WATER
  RESOURCES ABSTRACTS
  INPUT TRANSACTION FORM
                     1. Report So.
                                         3.  Accession No,
                                          w
  4. Title

     WEED HARVEST MD LAKE NUTRIENT DYNAMICS
  7. Author(s)

    Neel, Joe K.,  Peterson, Spencer A.,  and Smith, Wintfred L.
  S. Organization

     Department  of Biology
     University  of North Dakota

 12. Sponsoring Organization  Environmental Protection Agency

 is. Supplementary Notes Environmental Protection Agency report
                     number EPA-660/3-73-001, July 1973.
                                         5.  Report Date

                                         S.

                                         S.  Performing Organization
                                            Report No.

                                         10.  Project No.
                                         11. Contract I Grant No.

                                              16010 DFI

                                         13. Type of Report and
                                            Period Covered
  16.  Abstract After more than sixty years  of cultural eutrophication  Lake Sallie, Minnesota
    supports  dense growths of phytoplankton and rooted vegetation.   Its major water mass
    has the chemical character imparted  by photosynthesis at all  seasons,  and chemical
    effects of decomposition are rather  localized.  Phytoplankton dominance alternates
    among  diatoms, blue-green, and green algae in that order of abundance.  Prior to
    operation of a weed harvester, attached plants grew densely over 3W of the bottom
    area.  The bulk of nitrogen and phosphorus is usually contained in the water mass,
    with noticeably smaller amounts in upper bottom sediments and biota»  The fish
    population, less than one half the mass of weeds, contained considerable more N
    and P  than weeds in 1971.  Harvest in 1970 evidently reduced  weed density in 1971,
    and increased the cost per unit of nutrients removed.  Nitrogen and phosphorus
    removed in weeds were insignificant  when compared with annual water borne waste
    effluent  contributions to the lake.   Cost of phosphorus removal by weed harvest
    was $61 and $199 per pound in 1970 and 1971, respectively; nitrogen cost $8 and
    $21 and carbon $0.61; and $1.62 per pound for the same two years.
  17a. Descriptors
                 * Eutrophication, #Nutrients,  Nutrient budgets, Water pollution,
                   Nutrient distribution in lake water, sediments, biota
                   Watershed pollution,  Weed harvest and Nutrient Removal


  i?b. Identifiers   Eutrophication, Pelican  River,  Minnesota, Weed harvest and nutrient
                removal
  17c. COISRR Field & Group Q5  C
  18. Availability
19. Security Class.
   (Report)

20. Security Class.
   (Page)
21. No. of
   Pages

22. Price
                                                       Send To:
                                                       WATER RESOURCES SCIENTIFIC INFORMATION CENTER
                                                       U.S. DEPARTMENT OFTHE INTERIOR
                                                       WASHINGTON. D. C. 20240
  Abstractor Joe ft.  Neel
             \institutiop  University of North Dakota
WRSIC102(REV JUNE 1971)
                                                                                  EP 0 913.251

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