SEPA
United States
Environmental Protection
Agency
Environmental Research
Laboratory
Corvallis OR 97330
LPA GOO 8-79-017a
June 1979
Research and Development
The Effects of
Decreased Nutrient
Loading on the
Limnology of
Diamond Lake,
Oregon
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
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The nine series are:
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2. Environmental Protection Technology
3. Ecological Research
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This report has been assigned to the "SPECIAL" REPORTS series. This series is
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This document is available to the public through the National Technical informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/8-79-017a
June 1979
THE EFFECTS OF DECREASED NUTRIENT LOADING ON
THE LIMNOLOGY OF DIAMOND LAKE, OREGON
by
W. L. Lauer
G. S. Schuytema
W. D. Sanville
F. S. Stay
C. F. Powers
Corvallis Environmental Research Laboratory
Corvallis, OR 97330
CORVALLIS ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CORVALLIS, OR 97330
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DISCLAIMER
This report has been reviewed by the Corvallis Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publica-
tion. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
ii
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FOREWORD
Effective regulatory and enforcement actions by the Environmental Protec-
tion Agency would be virtually impossible without sound scientific data on
pollutants and their impact on environmental stability and human health.
Responsibility for building this data base has been assigned to EPA's Office
of Research and Development and its 15 major field installations, one of which
is the Corvallis Environmental Research Laboratory (CERL).
The primary mission of the Corvallis Laboratory is research on the ef-
fects of environmental pollutants on terrestrial, freshwater, and marine
ecosystems; the behavior, effects and control of pollutants in lake and stream
systems; and the development of predictive models on the movement of pollu-
tants in the biosphere.
This report documents the effects of diversion of domestic wastewater
from a freshwater lake.
James C. McCarty
Acting Director, CERL
iii
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ABSTRACT
Responding to accelerated recreational pressure at Diamond Lake, Oregon,
in 1969 the U.S. Forest Service began installation of a wastewater diversion
system which would eventually carry 85 to 90% of the sewage out of the water-
shed. From 1971 through 1977 the U.S. Environmental Protection Agency con-
ducted a program of research on the lake to determine its trophic status and
identify changes that might be the result of the diversion.
The lake is quite productive as the result of natural loading from tribu-
taries, groundwater and bottom sediments. Cultural influence, initially
speculated to be significant, was discovered to have a relatively minor impact
on the lake. Total phosphorus and chlorophyll a levels reached a low in 1973,
but by 1977 had increased to levels comparable to 1971. Species composition
of the benthic macroinvertebrate population was the same in 1976/77 as it was
at the beginning of the study.
Recommendations include an adaptation of the Dillon and Rigler system for
determining the development capacity of lakes.
The report covers a period from June 4, 1971 to October 27, 1977.
1v
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CONTENTS
Page
Foreword ^ 1
Abstract iv
Figures V1
Tables vii
Acknowledgment V111
Introduction 1
Historical Background 1
Conclusions 6
Recommendations 7
Study Design and Procedures 8
Diamond Lake Characteristics 12
Study Site 12
Hydrology 12
Nutrient Budget 14
Physical and Chemical Properties 22
Primary Producers 24
Benthic Macroinvertebrates 36
Management Applications 45
References 56
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FIGURES
Number £§S§
1. Map of Topography and development around Diamond Lake .... 2
2. Bathymetric map with lake sampling sites, tributaries
and wells .......................... 9
3. Average monthly hydrological budget (1972-1977) ....... 13
4. Total phosphorus volume weighted means ........... 23
5. Total inorganic nitrogen volume weighted means ....... 25
6. Secchi disc measurements .................. 27
7. Total phytoplankton volume weighted means .......... 30
8. Chlorophyll a volume weighted means ............. 34
9. Primary productivity volume weighted means ......... 35
10. Mean number benthic macroinvertebrates per square
meter ............................ 37
11. Dendrogram showing dissimilarity of benthic macro-
invertebrate populations .................. 44
vi
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TABLES
Number Page
1. Chronology of wastewater diversion and visitor use 4
2. Total phosphorus and total inorganic nitrogen
contributions from Natural Sources 15
3. Total phosphorus, total inorganic nitrogen and
total dissolved phosphorus in wellwater 17
4. Analysis of snow samples from ground 16
5, Phosphorus input minus output (1972-77) 18
6. Phosphorus contribution by sediments 19
7. Fishery contribution to phosphorus budget 21
8. Total phosphorus and total inorganic nitrogen
in wastewater 22
9. Total phosphorus and total inorganic nitrogen
volume weighted means at center station 26
10. Dissolved oxygen at center station, 13 m 28
11. Dominant phytoplankton volume weighted means 31
12. Benthic macroinvertebrates 38
13. Major macroinvertebrate groups and
percent composition , 1971-1977 40
14. Area! species richness, Shannon-Weaver diversity
and complement of Simpson's index of benthic
macroinvertebrate populations 42
15. The Dillon and Rigler system for estimating
acceptable P load and capacity for development 46
16. The critical load calculation according to Vollenweider ... 50
17. Rating of factors affecting present and
potential trophic status 51
18. Determining acceptable P load with a
minimum of field data 53
vii
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ACKNOWLEDGEMENTS
The following persons were instrumental in the experimental design, field
and laboratory work: Karl R. Rukavina, Alan V. Munhall, Julie A. Searcy and
Spencer A. Peterson.
Judy 8. Carkin, Richard C. Swartz and James Keniston assisted with sta-
tistical analysis and data collation.
From the U.S. Forest Service, Robert Sawyer and Dallas Hughes were ex-
tremely helpful in supplying information and assisting with field work.
Jerry Bauer of the Oregon Department of Fish and Wildlife provided data
generated from their studies at Diamond Lake.
vm
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INTRODUCTION
Many mountain lakes in Oregon and Washington are subject to heavy recrea-
tional use during the non-winter months. Intensive use frequently results in
greatly increased nutrient flux to lakes with a consequent acceleration of
eutrophication rates and degradation of water quality. This study documents
the impact of a waste-water interception program at Diamond Lake, Oregon, with
emphasis on defining the nutrient budget and describing the benthic macroin-
vertebrate population. Recommendations are made which could provide a basis
for scientific lake management.
HISTORICAL BACKGROUND
Diamond Lake lies at an elevation of 1580 m in the Cascade Mountains
approximately 24 km north of Crater Lake, Oregon. The lake resulted from the
melting of an extensive glacier held behind a lava flow from Mt. Thielson,
perhaps 10,000 years ago (Purdom, 1964).
Development around Diamond Lake began in the 1920's. The first building
permit was issued in 1922 for a lodge at the northeast corner of the lake
(Cleator, 1924). A private resort complex now encompasses 15 ha of land
including approximately 250 m of shoreline. Guest capacity is 384 persons.
Another service facility occupying approximately 0.6 ha is located near the
southeast corner of the lake. A trailer park, also near the southeast corner,
can accomodate 115 trailers on 6.5 ha (U.S. Forest Service [USFS], 1970).
At one time a YMCA camp occupied approximately 4 ha at the southwest
corner of the lake. It consisted of a lodge and 14 cabins, but has not been
used since 1971 (USFS, 1970). The first private recreation residence was
approved in 1923. Presently there are 102 such dwellings occupying 19 ha of a
designated 75 ha plot on the west side of the lake (USFS, 1970). A buffer
strip of vegetation, including tall conifers, was left between the dwellings
and the lake to maintain the integrity of the shoreline.
About 1948 four cabins were built next to the outlet to accommodate
personnel from the Diamond Lake fishegg-taking station. These buildings are
now used occasionally by the Oregon Department of Fish and Wildlife (DFW).
The USFS, which primary has responsibility for land management of the
Diamond Lake area, maintains three campground complexes totaling approximately
88 ha. The largest of these, East Shore Campground, occupies 40 ha in a
narrow strip on the east shoreline. It has 190 trailer/ tent and 50 tent only
sites. Two picnic areas, comprising more than 6 ha, are also part of the
development (USFS, 1970). All development immediately around the lake is
shown in Figure 1.
-------
Scale
1HTP
Figure 1. Topography and development around Diamond Lake (elevations in feet),
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Recreational use of Diamond Lake has increased rapidly: it has become
one of the most popular areas in Oregon. In 1923 slightly more than 9,000
people were estimated to have visited the lake (Cleator, 1924). The camp-
grounds show a visitor-day (12 hr) increase from less than 30,000 to over
104,000 from 1956 to 1963 (Oregon State Game Comm. , 1963). By 1965 the USFS
reported use of all developed areas at over 307,000 visitor days (Robertshaw &
Thorpe, 1965) and by 1977 the figure had more than doubled to 670,000 (R.
Sawyer, District Engineering Asst., Diamond Lake Ranger Dist., USFS, pers
comm.). Heaviest use occurs in the summer during the fishing season but
snow-oriented recreation is increasing.
The USFS has maximized the recreation value of the Diamond Lake area.
Around 1913 they stocked the lake with trout (Bauer, 1976). Grazing sheep in
the meadows was discontinued in the 1920's. Timber harvesting is limited to
only the salvage and removal necessary to promote recreation (USFS, 1970).
The DFW (formerly the Oregon State Game Commission) began intensive study
and management of the fishery in 1946 in response to an apparent decline in
the size and number of rainbow trout, Salmo gairdneri (Locke, 1947). Spot
poisoning of the roach, Siphateles bicolor bicolor, apparently introduced in
the early 1930's (Bauer, 1976), was initiated in 1946 to reduce competition
with trout. In September 1954 the roach was completely eradicated by inten-
sive rotenone application. The lake was restocked in June 1955 with Canadian
rainbow trout (Oregon State Game Comm. 1954, 1955). Data regarding fishing
pressure and success, fish growth and fish food production are gathered by the
DFW to direct management policies.
A mosquito control program was initiated in the early 1960's. DDT was
used initially but discontinued when mayfly nymph numbers dropped, substan-
tially reducing an important fish food (J. Bauer, District Fishery Biologist,
DFW, pers. comm.). Benzene hexachloride was applied in 1968 and 1969. The
present program involves one application of MLO Flit (a thin oil) on the marsh
immediately after snow melt and weekly application of Malathion in the camp-
grounds from June thru August by the Douglas County Sanitation Department (G.
Ferell, Sanitarian, Douglas County, OR, pers. comm.).
The USFS recognized the potential deleterious effects of cultural eutro-
phication resulting from increased visitor use. Periodic blooms of algae were
noted at Diamond Lake even in the 1930's (Hughes, 1970). In 1966 the waste
collection and treatment needs were evaluated. Considering visitor use pro-
jections and possible health and aesthetic consequences of continued use of
the existing septic tank and pit toilet facilities, a plan was designed for an
improved sanitation system including "modern comfort stations, sewer connec-
tions for house trailers and camper trucks, improved water supply connections
and services, fish cleaning facilities and other conveniences" (Burgess,
1966). Wastes from the campgrounds at the south and east sides of the lake,
the trailer court and the resort along the east and northeast section were to
be diverted to a series of lagoons outside the watershed. Along the west
shore of the lake, the former YMCA camp, summer homes and Thielson View Camp-
ground would not be connected but pit or septic tank-type systems would be
replaced with vaults which could be periodically pumped. In 1970 the first
use was made of on-line facilities at East Shore Campground. By December 1975
all planned connections had been completed (Table 1).
3
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TABLE 1. VISITOR USE AND CHRONOLOGY OF WASTEWATER DIVERSION
Date of
Site Diversion
East Shore 4 stages:
Campground 9/69, 11/70
11/72, 06/73
South Shore 11/72
Picnic Area
Broken Arrow 08/74
Campground
Diamond Lake
Improvement Co. 06/75
Diamond Lake
Trailer Court 12/75
Thielson View —
Campground
Noble Fir
Summer Homes —
YMCA
Totals —
69
179.
5.
27.
221.
67.
8.
—
39.
5.
555.
4
4
7
4
8
8
2
3
0
70
178.
7.
24.
209.
72.
14.
0.
40.
5.
552.
Visitor Days (xlO3)
71 72 73
8
7
4
7
0
2
2
0
3
3
210
3.3
15.5
138
63.4
20
0.1
18.2
2.5
471.0
207.3
4.6
3.8
136
64
27.7
0.1
20.2
0
463.7
221.9
5.4
13.7
146
59.5
38.9
0.1
36.8
0
522.3
74
201.4
7.0
closed
160*
64.6
49.9
0.1
43.8
closed
526.8
75
247.0
4.3
10.4
182.7
37.8
58.0
0.1
49.8
closed
590.1
76
247.0
2.4
34.9
226.8
46.6
52.7
0.1
58.2
closed
668.7
77
221.0
3.3
63.0
235.1
46.6
52.0
—
47.2
closed
668.2
Our interpolation - not USFS data
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In 1971 the USFS and the U.S. Environmental Protection Agency (EPA)
signed a Memorandum of Agreement for a study to determine the existing lake
trophic status, sources of nutrients or other pollution, and whether signifi-
cant improvement could be detected as a result of the new waste collection and
treatment system. The National Eutrophication Research Program, established
within EPA as a result of national interest in water quality, had as one of
its objectives the determination of the effectiveness of various lake restora-
tion techniques. The Diamond Lake project offered an excellent opportunity to
assess the effects of nutrient diversion on lake trophic condition.
The raw data generated during this study is reported in an Appendix as the
Environmental Protection Agency's Special Report EPA-600/8-79-017b. The data
report is available from the National Technical Information Service, Spring-
field, VA 22161.
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CONCLUSIONS
1. Diamond Lake is mesotrophic to eutrophic as a result of natural nutrient
loading from the tributaries, groundwater and sediments.
2. The nutrient contribution from cultural activities in the watershed is,
at present, relatively insignificant compared to natural sources.
3. During the period of this investigation no change was found in the tro-
phic status of the lake that could be attributed to the wastewater diver-
sion system.
4. The trophic status of Diamond Lake is appropriate in satisfying present
recreational demands.
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RECOMMENDATIONS
The present trophic status of Diamond Lake should be perpetuated. Cul-
tural activity and development should be managed to minimze the artificial
nutrient supply to the lake.
Surveillance of Diamond Lake's trophic status should continue. It is
recommended that during the summer, from June through September, monthly
samples be collected from the center station at 1 meter for nutrient and
chlorophyll analysis, and that Secchi disc measurements be made. More fre-
quent sampling would be preferable. Sampling and analytical techniques should
be comparable to those cited here.
A nutrient budget should be developd before implementation of a plan to
alter the trophic status of any lake and should include an accurate assessment
of the groundwater contribution.
When applying predictive models precise field measurements should be used
whenever available instead of estimates and generalizations.
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STUDY DESIGN AND PROCEDURES
The EPA field program began in June 1971. Seven lake sampling stations
were established. Silent Creek, the major inlet, and Lake Creek, the only
outlet, were sampled for chemical characterization and to aid in determining a
nutrient budget. Hydrologic information was provided by the U.S. Geological
Survey (USGS). Three lake stations were on the central axis and four around
the periphery, adjacent to the campgrounds, summer homes and resort. At the
three deeper, center stations, water was collected at 5-meter depth intervals
starting at the surface (e.g., 0, 5, 10, 13 m at the deepest station). Sam-
ples were collected at the surface and 5 m from the peripheral stations.
In 1973 sampling of Short Creek was initiated, but the number of lake
sampling sites was reduced to 4 by eliminating the Thielson View, north-center
and south-center stations. A two way analysis of variance, with dates and
sites as the factors, demonstrated no significant chemical differences between
lake stations at the 0.05 level of significance. In 1974 water sampling at
the 3 peripheral stations was discontinued for the same reason, but benthic
macroinvertebrate sampling was continued. This same year, intermittent tribu-
taries were added. Camp, Dry, Porcupine, Rabbit, Spruce and Two Bear Creeks
were sampled to lend more precision to the nutrient budget. The four lake
sampling stations retained throughout the study are shown in Figure 2.
Sampling was monthly from soon after ice-out until the weather became
restrictive, usually in October. Winter samples were collected through the
ice in 1972 and 1975.
Lake water was collected with a PVC Van Dorn bottle and distributed to
polyethylene containers. Tributaries were sampled by dipping the polyethylene
containers directly. Specific conductance, pH and dissolved oxygen (DO)
determinations were done in the field, in situ when possible. From 1975-77, a
multiple parameter sensing unit was used. The New England Research Associ-
ates, Inc. Model 4 Environmental Monitor (NERA Inc, Bedford, MA) recorded jn
situ temperature, conductance, pH, DO, redox potential and depth. Earlier DO
analysis followed the azide modification of the Winkler method. Data were
recorded at 1 m intervals from surface to bottom at the center station.
Transparency was measured with a 20 cm Secchi disc.
Chemical analyses generally were done at the EPA laboratory in Corvallis.
Samples for nutrient and metals analysis were field stabilized with mercuric
chloride and nitric acid, respectively, before transportation. Standard EPA
methodology (EPA, 1971) generally was followed.
Chlorophyll analyses were conducted according to Strickland and Parsons
(1965) as modified by EPA (1973), and primary productivity was assessed by the
14C method described by Goldman et aj. (1971). Light was measured with a
8
-------
Scale
O
Figure 2. Lake bathymetry and sampling sites.
9
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Lambda Instruments LI 185 Quantum/Radiometer/Photometer with a LI 192S under-
water quantum sensor. Measuring sensitivity was between approximately 400 and
700 nm.
Phytoplankton samples were collected along with those for chemical analy-
sis. From 1971 to 1973 they were preserved in 3-5% formalin and counted using
a Sedgewick-Rafter counting cell in a modification of the clump count (Ameri-
can Public Health Association, 1971). The modification involved determining
an average number of cells for all filamentous forms and multiplying this by
the number of filaments to give a final estimated cell number.
Samples collected from 1974 through 1977 were preserved with Lugol's
solution and counted and identified using an inverted microscope (Lund, 1958,
EPA, 1973). Direct cell counts were made except in the case of forms such as
Eudorina, Pandorina, Coelastrum and Gloeotrichia where colonies were counted.
Counts of Melosira and Oscillatoriaceae were expressed as number of 100 urn
lengths and included with the cell counts.
Center station profiles have been reduced to a volume weighted mean (VWM)
for the lake. Using a bathymetric chart a volume was associated with each of
the depths sampled. For example, the volume associated with the 10 m sample
is:
Vio = [(A7.s + AH. s)/2:i x (11.5 m - 7.5 m)
where A7 5 = the area associated with the 7.5 m contour and A11-5 = the area
of the 1*1.5 m contour. The solution (V10) would be the volume of a cylinder
with base area (A7>5 + A11>5)/2 and length (11.5 m - 7.5 m). A similar calcu-
lation was made for the o'ther sample depths using appropriate contour areas
and lengths of water column. The whole lake VWM for any parameter, then,
would be:
x = I V1 - x. / VL
i=o
where V. = the volume of the sampled strata; x. = the concentration of the
. = the volume of the sampled strata; x.
1strata and V. = the sum of the volumes of
sampled strata and V, = the sum of the volumes of the 4 strata (the volume of
the lake).1 Chemistry samples were generally collected at 0, 5, 10, and 13 m.
Primary productivity and chlorophyll a were usually measured at 0, 1, 4, 7,
10, and 13 m. The calculation strategy is the same for both regimes. All
lake concentrations and phytoplankton cell numbers discussed are VWM's unless
otherwise defined. The average concentrations for the various tributaries are
arithmetic means - not volume weighted according to flow.
Hutchinson (1957) describes the formula for volume of a lake stratum as
Vm =
-------
Triplicate benthos samples were collected in 1971 and 1972 with a Ponar
grab, washed in the field through a U.S. Standard No. 30 (0.59 mm) mesh screen
and preserved in 10% formalin. In subsequent years, four samples were col-
lected at each site. A U.S. Standard No. 60 (0.25 mm) mesh screen was used in
laboratory sample rinsing to reduce the loss of small forms. The retained
organisms were preserved in 70% alcohol, and, where possible, identified to
species.
Benthic community structure was characterized with several common mea-
sures or indices. Estimates of richness (number of species) and diversity (a
function of richness and species frequency distribution) were calculated from
only the number of identified species plus taxa apparently composed of only
one species rather than the total number of taxa, to increase the reliability
of station- to- station comparisons.
Species area! richness, expressed here as the number of species per
single grab was calculated according to Hurlbert (1971). The following in-
dices were calculated from pooled replicate grab samples at each station.
Dominance concentration as indicated by Simpson's diversity index (Simpson,
1949) gives the probability that any two individuals drawn from a multispecies
assemblege will be the same. This index is not greatly affected by sample
size; its complement (Mclntosh, 1967) was calculated to relate it positively
to diversity:
_
1 " S'L =
N (N - 1)
Where N is the number of individuals, n. is the number of individuals in the
i species and S is the number of species.
Species diversity, as indicated by the popular Shannon-Weaver expression
(Pielou, 1970)(a measure of the mean diversity per individual integrating
concepts of both richness and species frequency), was calculated by:
S n. n,
H1 = -I -J Iog10 (-1)
1=1
Numerical classification or cluster analysis of the data (Boesch, 1977;
Swartz, 1978) was performed using the program CLUSTER on Oregon State Univer-
sity's CDC 3300 computer to describe spatial and temporal faunal homogeneity
between collections.
11
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DIAMOND LAKE CHARACTERISTICS
STUDY SITE
Diamond Lake has a surface area of 1243 ha and a total watershed of
approximately 142 km2. Maximum depth is 14.3 m while the average is 7.2 m.
The volume is approximately 9.02 x 107 m3. Hydraulic retention time averages
1.5 years. The lake is elongated on a north-south axis, approximately 5.5 km
long by 2.5 km wide (Figure 2). Basin morphometry is regular with a single
central depression.
The topography and geology of the area is dominated by its volcanic
history. The basin is flanked by the High Cascade volcanoes, Mt. Thielson
(2799 m) and Mt. Bailey (2549 m). Timber Crater (2256 m) marks the southern
point of the watershed. The soils are in the "Crater Lake Series," porous and
well drained, with greater than 1.5m volcanic ash and pumice (D. Hanson, Soil
Scientist, Douglas Co. OR, pers. comm.). They include glacial debris, pumice
and ash from the eruption of Mt. Mazama which collapsed to form the caldera
containing Crater Lake (Purdom, 1964). The bedrock is basaltic, the remnant
of lava flows from Mts. Bailey and Thielson.
The watershed contains mostly coniferous forest with lodgepole pine
(Pinus contorta), mountain hemlock (Tsuga mertensiana), and firs (Abies sp.)
predominating. The groundcover includes huckleberry (Vaccinium sp.), grasses
(Graminae), sedges (Carex sp.), and manzanita (Arctostaphylos sp.) (Meyerhoff,
1977). At the south end of the lake is a 60 ha marsh.
HYDROLOGY
Silent Creek drains an area of approximately 36 km2 at the southwest
corner of the lake's watershed, accounting for about 25% of the total. The
water is generally very cold and clear. After a storm in 1977, however, the
stream was humic brown, suggesting an influence from the marsh through which
it flows. Silent Creek accounted for an average of 56% of the total measur-
able inflow during the study. Percent contribution ranged from 26% during a
month of extreme precipitation to 78% when precipitation was negligible.
Maximum recorded flow was 3.233 x 106 m3/mo for June 1972, while the minimum
was 1.715 x 106 m3/mo recorded for February 1974. The average annual input
for the study period was 28.005 x 106 rnVyr (Figure 3).
The other major tributary, Short Creek, averaged 20% of the measurable
inflow. The range for monthly flow over the study period was 0.613 x 106
m3/mo to 1.370 x 106 m3/mo with an annual average of 10.007 x 106 m3/yr. The
stream originates as a large spring only a few hundred meters from the lake
and runs extremely cold and clear throughout the year.
12
-------
INPUT
20-
\ xx v Precipitation
° \
10-
ro
in
O
Short Creek
Misc. Creeks
_^k*«M^^M^H^^^^H
~~ I ~~ I f
OUTPUT
60-
o
>
40-
20-
Evaporation r
*»t
mx
,0*..
o I o i
JFMAMJJASOND
MONTH
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Vol.(xl05m3)
IN
56.14
42.85
49.06
39.42
49.31
5 1.04
37.49
36.37
34.85
38.79
48.97
53.05
OUT
69.91
53.72
65.26
51. 17
51.06
70.53
47.34
33.97
33.98
53.72
67.83
65.46
Figure 3. Average monthly hydrological budget (1972-1977).
-------
The intermittent tributaries to Diamond Lake have significant flow only
during snow melt. Their maximum contribution was 30% of the directly measur-
able inflow, 1.863 x 106 mVmo in June 1974. The average annual contribution
was only 3%.
Precipitation was measured as water falling directly onto the lake. In
November 1973 it accounted for 64% of that month's directly measurable input
at 5.084 x 106 m3/mo (41 cm). Maximum contribution generally occurred in the
winter (Figure 3). Yearly precipitation ranged from a low of 65 cm in 1976 to
a high of 127 cm in 1975, averaging 19% of the measurable input over the study
period.
Groundwater input was estimated by subtracting measurable inflow from
measurable outflow. Over the six-year study period an average 21% of the
outflow was unaccounted for by measured inflow and was attributed to ground-
water.
Water loss has three possible significant components: surface outflow,
evaporation and groundwater export. The USGS supplied data for the first two
but no estimate for groundwater export could be gained. Since measured out-
flow was greater than inflow throughout the study, groundwater losses were
assumed to be zero.
Surface outflow is continuous but the rate is regulated by the DFW.
Flashboards are generally installed in Lake Creek after spring runoff to
maintain the lake level during the summer, then removed in the fall. Maximum
outflow is generally in the winter (Figure 3) but the highest flow gaged was
in June 1974, at 10.711 x 106 mVmo. Minimum flow measured was 1.040 x 106
mVmo in September 1975.
Greatest evaporation occurs in July or August. The maximum reported over
the study period was 1.431 x 106 m3 for July 1973. In August 1974, evapora-
tion was reported equal to Lake Creek outflow.
NUTRIENT BUDGET
Major nutrient sources to Diamond Lake include tributaries, groundwater,
precipitation, bottom sediments and human activities. Total natural load is
defined as the sum of the loads from the tributaries, precipitation and
groundwater.
Silent Creek, the dominant hydrologic influence, is also the main source
of phosphorus (P). Over the study period the average total phosphorus concen-
tration (TP) for Silent Creek was 0.056 mg/1. Its average yearly P contribu-
tion was 1549 kg, accounting for an average 61% of the total measurable nat-
ural load (Table 2).
The P contribution from Short Creek averaged 22% of the total natural
load from 1972 through 1977 (Table 2). The average concentration was approxi-
mately 0.055 mg P/l resulting in an average yearly load of 548 kg.
14
-------
TABLE 2. NUTRIENT CONTRIBUTIONS FROM NATURAL SOURCES
Sil
ent Cr.
Short
Cr.
Interm
Str.
Precip.
Ground
H20
TOTAL
Phosphorus
1972
73
74
75
76
77
Avg
1972
73
74
75
76
77
Avg
kg
1766
1586
1320
1429
1528
1662
1549
kg
262
640
412
457
355
313
407
%tot
57
65
57
56
64
67
61
%tot
4
13
6
6
8
9
8
kg
691
527
409
589
522
549
548
kg
259
338
200
168
177
133
213
%tot
22
22
18
23
22
22
22
%tot
4
7
3
2
4
4
4
kg
162
6
105
58
57
16
67
Inorganic
kg
60
1
43
24
27
5
27
%tot
5
0
5
2
2
1
3
Nitrogen
%tot
1
0
1
0
1
0
1
kg
125
129
126
137
71
96
114
kg
515
529
516
565
291
395
469
%tot
4
5
5
5
3
4
4
%tot
7
10
7
8
6
12
8
kg
353
201
341
341
218
143
266
kg
6271
3564
6055
6046
3871
2531
4723
%tot
11
8
15
13
9
6
10
%tot
85
70
84
83
82
75
80
kg
3097
2449
2301
2554
2396
2466
2544
kg
7367
5072
7226
7260
4721
3377
5837
-------
The average concentration of the intermittent streams from 1973 through
1976 was 0.033 mg P/l. The intermittent streams were not sampled before 1973
and only Two Bear Creek had significant flow in 1977. Two Bear Creek exhibi-
ted the highest average TP of all sources measured, approximately 0.071 mg/1.
It drains the resort complex. The TP contribution from the intermittent
streams was only about 3% of the total, insignificant compared to the major
tributaries and groundwater.
Groundwater loading was estimated from analyses of well water (Table 3,
Figure 2) together with surface outflow minus inflow volume calculations. The
P load was based on total dissolved phosphorus (TOP) rather than TP since the
turbid well water resulted in unrealistically high TP concentrations (mean =
0.287 mg/1, n = 26, excluding 2 values of 11.9 and 5.1 mg/1). Average TOP was
0.020 rag/1 (n = 27, one value of 0.48 ing/1 excluded). The groundwater contri-
bution, then, averaged an estimated 10% of the external P load. Average
yearly load was 266 kg.1
Precipitation, while averaging approximately 19% of the yearly inflow,
contributed only about 4% of the annual P load. Total phosphorus concentra-
tion of precipitation was estimated from analyses of composited snow cores
collected in the springs of 1973, 74, 75 and 76 (Table 4). The average was
<0.009 mg P/l. Loading from direct precipitation on the lake averaged 114
kg/yr.
TABLE 4. SNOW ANALYSIS
Date TP TSP OOP NH3 N02 N03 KjlN
12/15/73
05/10/74
03/05/75
06/05/75
05/20/76
AVG
<.005
.01
<.01
<.01
.01
<.009
<.005
<.005
<.01
<.01
.01
<.008
.004
.01
<.005
<.005
.005
<.006
.021
—
.024
.005
.03
.02
.001 .018 .3
.3
<.l
.1
.15
<.19
Sediment samples collected in 1971 averaged 520 |jg P/g dry sediment with
a range of 340 to 700 ug/g (Sanville and Powers, 1971). Interstitial water
averaged 250 ug ortho phosphate-P/1. No attempts were made to measure P
contribution from sediments directly. Yearly nutrient loading calculations
for 1972 through 1976 show an average retention of approximately 40% of the
external P load. In 1977, however, it appears that 2% more left the lake than
entered (Table 5).
Short Creek might be representative of groundwater. The creek is essen-
tially a spring which enters the lake after flowing above ground only a
few hundred meters. If Short Creek data were used, the average TP load
from groundwater would be 746 kg/yr or an average of 25% of the total
load.
16
-------
TABLE 3. WELL WATER ANALYSIS
06/14/7?
06/26/72
(mjl) 07/10/72
07/25/72
06/14/72
06/26/72
(m /I) 07/10/72
07/25/72
06/14/72
06/26/72
(mg™ °7/10/72
07/25/72
1
Summer
Homes #1
.003
.03
.002
.016
.012
.001
.001
.056
.113
.032
.032
>.003
2
Summer
Homes #2
.08
.208
.054
.050
.004
<.001
.002
.11
.043
.025
.060
.055
3
Summer
Homes #3
.16
.381
.077
.075
.002
<.001
<.001
.061
.055
.049
.053
.054
4
Campsite
R6
.94
11.9
.115
.385
.005
.004
.003
.072
.197
.324
.395
.308
5
Trai ler
Disposal
.029
.243
.008
.32
.015
.002
<.001
.084
.357
.875
.838
.868
6
Resort
Cabins
5.1
1.57
.055
.240
.001
<.001
<.005
.053
.164
.143
.184
.171
7
Resort
Parking
.082
.4
.058
1.87
.008
.014
.022
.48
.936
1.226
1.683
>.177
-------
TABLE 5. PHOSPHORUS INPUT* MINUS OUTPUT
Year
1972
73
74
75
76
77
Input
(kg TP)
3097
2449
2301
2554
2396
2466
Output
(kg TP)
2619
1499
858
1256
1510
2514
In-Out
478
950
1443
1298
886
-48
%
Retention
+ 15
+ 39
+ 63
+ 51
+ 37
-2
* Refers to "natural" input by tributaries, groundwater and precipitation.
One indirect approach for determining sediment P contribution involves
accounting for the change in the mass of P in the water over some time period,
the load into the lake and the export from the lake (Schindler et al., 1973).
Total mass of P at any time is calculated from the lake volume and the TP
volume weighted mean. For application of this approach two time periods were
distinguished, summer and winter. Since tributaries were not sampled during
the winter, concentrations were estimated by averaging the last three analyses
of the preceding summer with the first three of the succeeding summer (e.g.,
August 18, September 15 and October 14, 1976 with April 28, June 2 and July
20, 1977). Winter external loading (import and export) values are not as
reliable as those for summer and may limit confidence in the sediment P re-
lease calculations. (Note: Two TP analyses of Silent Creek were unchar-
acteristic, 0.310 mg/1 on October 7, 1971, and 0.270 mg/1 on August 7, 1974,
and were disregarded as outliers in all loading and budget calculations.)
Sediments showed a net P accumulation from September 1971 to October 1977
(Table 6). However, substantial quantities were apparently released in the
winters of 1973-74 and 1976-77. The greatest calculated release was 2316 kg
during the winter of 1976-77. Considering that the greatest sediment P con-
tribution probably originates below 13 m where low DO is common, this quantity
is comparable to P release determined by Larsen et aj. (1978) in Shagawa Lake,
Minnesota. Maximum accumulation of P also appeared to occur during winter
periods—the winter of 1971-72 being highest at 7063 kg.
Rooted aquatic vascular plants might be another possible internal nutri-
ent load source. At maximum density approximately 30-50% of the bottom of
Diamond Lake is covered by vegetation. This area occupies the zone roughly
between 2 and 8 meters. No attempts were made to measure P contribution from
this source, but excretion of P by aquatic vascular plants is well documented
(e.g., McRoy et aJK , 1972 and DeMarte and Hartman, 1974). Death and decay of
the plants in the fall would also add to the phosphorus pool. Large mats of
Elodea and Potomogeton wash up on the shore during storms, indicating the
potential for a large nutrient influx. Every fall waterfowl arrive in great
numbers at Diamond Lake. Feeding on aquatic weeds, they hasten the decomposi-
tion of the plants and the recycling of the contained nutrients.
18
-------
TABLE 6. SEDIMENT CONTRIBUTION TO TP
Period
09/27/71-05/24/72
05/24/72-08/22/72
08/22/72-05/23/73
05/23/73-10/18/73
10/18/73-06/05/74
06/05/74-10/09/74
10/09/74-06/05/75
06/05/75-10/22/75
10/22/75-05/20/76
05/20/76-10/14/76
10/14/76-04/28/77
04/28/77-10/27/77
A Lake
TP Mass (kg)
-8209
+ 451
-2345
- 541
+1804
+ 631
+1083
- 541
-2255
+ 631
+2706
-1804
In-Out (kg)*
-1146
+ 326
+ 719
+ 506
+ 234
+ 532
+ 909
+ 535
+ 311
+ 456
+ 390
+ 99
Net
Sediment
Release (-) or
Accumulation (+)
+7063
- 125
+3064
+1047
-1570
- 99
- 174
+1076
+2566
- 175
-2316
+1903
+12,260 kg
* Refers to "natural" input by tributaries, groundwater and precipitation
minus output by Lake Creek.
19
-------
Analysis of rainbow trout taken from the lake indicated a dry weight
concentration of 1.7% P. Table 7 shows that the annual fish harvest removes a
substantial amount of P. The record catch of 1973 removed approximately 550
kg P. Stocking of trout is a minor nutrient source. The average yearly total
mass of fish stocked from 1971 through 1977 was 3450 kg, amounting to only
approximately 15 kg P.
Fishing practices can contribute to the nutrient load. McHugh (1972)
reported an estimate of one ton (~900kg) of cheese used in Diamond Lake in
less than one week as bait. Assuming 10,400 angler days in a busy week (July
2, 3, 4, 1977, recorded 4472 angler days)(J. Bauer, District Fishery Biolo-
gist, DFW, pers. comm.) and 0.77% P in pasteurized processed American cheese
(wet weight)(Adams, 1975), the 1977 fishing season (102,043 angler days)(J.
Bauer, pers. comm.) could have added nearly 70 kg P to the lake. This quan-
tity is about the same as the annual contribution from all intermittent
streams averaged over the study period.
Total inorganic nitrogen (TIN) appears to be dominated by the ground-
water. Analyses of unfiltered well water averaged 0.355 mg TIN/1 (Table 3).
While all other surface sources averaged less than 10% of the yearly load
(Silent Creek and precipitation each averaged 8%) the groundwater averaged 80%
(Table 2).1 The average total yearly load was 5837 kg TIN/yr, however, no
attempt was made to quantify nitrogen fixation and denitrification, processes
that greatly complicate N dynamics in an aquatic system.
Maximum P and N diverted by the wastewater system were estimated. Sam-
ples of wastewater collected at the main pumping station between 1973 and 1976
averaged 5.59 mg P/l (Table 8). Information supplied by the USFS (R. Sawyer,
District Engineering Assistant, Diamond Lake Ranger District, USFS, pers.
comm.) showed that lagoon influent totaled 5.96 x 104 m3 in 1976 with 5.58 x
105 visitor days and 5.67 x 104 m3 in 1977 with 5.69 x 10s visitor days (avg.
= 0.103 mVvisitor day). Total influent includes groundwater intrusion to the
system. The maximum P diverted for 1976 and 77 was approximately 333 and 317
kg, respectively, or 14 and 13% of the natural loadings for those years.
Total inorganic nitrogen averaged greater than 12.39 mg/1, equivalent to a
maximum diversion of over 738 kg in 1976 and 703 kg in 1977.
Algal assays of water collected from Diamond Lake in July 1971 showed P
to be the potential limiting or algal growth controlling nutrient at that time
(Miller et al_., 1974). A sample collected at the end of March 1972, also
showed potential P limitation (T. Shiroyama, unpublished data). Other analy-
ses by Shiroyama indicated N limitation in March and August 1973. The Na-
tional Eutrophication Survey (EPA, 1978) reported N limitation in July and
October 1975, based on N:P ratios. The nutrient limiting algal growth does
commonly change in productive lakes (Greene et al., 1976). Phosphorus could
become limiting during a bloom as it is incorporated in the biomass. Relative
TIN from Short Creek averaged approximately 0.021 mg/1. Using this value
the average load from groundwater would be approximatly 280 kg TIN/yr or
20% of the average total load which would be reduced to about 1400 kg/yr.
See note p. 16.
20
-------
TABLE 7. FISHERY CONTRIBUTION TO PHOSPHORUS BUDGET
1971 1972 1973 1974 1975 1976 1977
Wet Weight Fish 3640 2712 2091 3688 5922 3037 3057
Stocked (kg)
Phosphorus Content 16.0 11.9 9.2 16.2 26.1 13.3 13.5
Fish Stocked (kg) *
Wet Weight Fish 87,276 76,271 128,122 127,959 91,953 75,397 94,749
Caught (kg)
Net to (+) or from (-) -368.0 -323.7 -554.5 -546.8 -378.5 -314.4 -403.4
Lake (kg TP)
* Analysis of Diamond Lake Trout showed: P = 1.68% x dry weight, and
Dry Weight = 26.4% x wet weight
Therefore', P = 0.0044 x wet weight
Stocking and harvest data from Jerry Bauer, Ore. DFW
-------
TABLE 8. TP AND TIN IN WASTEWATER
Date
05/24/73
06/19/73
07/17/73
08/15/73
08/26/73
09/12/73
03/05/75
08/14/75
09/19/75
08/19/76
10/15/76
04/29/77
Avg.
TP
(ing/1)
0.06
5.15
8.75
6.6
0.97
2.7
0.8
14.5
9.5
—
6.9
—
5.59
TIN
(mg/1)
0.005
28.14
22.27
—
5.59
15.12
>2.1
>21
>9.1
>14
—
6.61
>12.39
to the nutritional requirements of algae, however, (Miller et aj[.,. 1976) the
external loading figures suggest that N is proportionately less well supplied
to Diamond Lake than is P. Nitrogen limitation of algal growth might be
expected.
PHYSICAL AND CHEMICAL PROPERTIES
The lake is a temperate, dimictic water body which completely mixes in
the spring and fall, stratifying in the summer and in winter under ice. It
has been described as mesotrophic to eutrophic based on identification of
diatom frustules in the sediments (Meyerhoff, 1977). Sanville and Powers
(1971) characterized the lake as "quite productive" but not extremely eutro-
phic.
Total phosphorus concentrations decreased from 1971 to 1973 (Figure 4).
Averages for those years were 0.062 and 0.028 mg P/l respectively, a reduction
of over 50%. After 1973, however, there was a gradual increase, reaching
0.051 mg/1 for 1977. The maximum TP, 0.133 mg/1 on September 27, 1971, is
uncharacteri sti c.
II 4. II
Total phosphorus data from 1971 through 1975 were pooled and compared by
•t" test at the 0.05 level of significance to pooled data from 1976 and 1977
when the diversion was complete. The 1976/77 average, 0.05 mg/1, was signifi-
cantly higher than the average of the previous five years, 0.03 mg/1 (exclud-
ing the 0.133 mg/1 value from 1971). The 1977 average, again approximately
0.05 mg/1, is different at the 0.01 level under the same condition.
The reasons for the increase are unclear: natural variability is prob-
ably the dominant factor. At approximately 670,000 visitor days, 1976 and
1977 are only about 13% higher than the 1975 recreation use total and virtu-
ally all of that increase was served by the wastewater diversion system (Table
22
-------
ro
GO
.16-
(S)
cr .12
o
O
x .08-
CL
O .04
h-
1971
1972
1973
1974
1975
1976
1977
Figure 4. Total phosphorus volume weighted means.
-------
1). Inflow dropped by over 20% from 1975 to 1976 and another 10% from 1976 to
1977. This would extend the hydraulic retention time of the lake which would
tend to exacerbate eutrophic conditions. At the same time, however, the
natural nutrient loading decreased with the inflow (Table 2). The data show
(Table 5) that in 1977 P washout exceeded natural input and Table 6 indicates
that the sediments are responsible for releasing large amounts of P. Sediment
release apparently provided sufficient P to stimulate and maintain a large
phytoplankton population during the summer of 1977. Apparently it reaccumu-
lated in the sediments by the end of the summer.
Total inorganic nitrogen yearly averages show no particular pattern
(Figure 5). The maximum concentration was 0.389 mg TIN/1 on August 14, 1973
and relatively high values were found in 1972, 1976 and 1977. Over the whole
study period, however, 28 of the 34 values were less than 0.060 mg/1 (Table
9). Total inorganic nitrogen was not determined in 1974.
The initial Secchi disc measurement each year was at or near the lowest
value for that year (Figure 6). The lowest recorded transparency was 2.1 m on
September 27, 1971, but similar measurements were made in June 1971 and April
1977. Highest values for any given year generally occurred in early summer,
with a maximum of 10.5 m observed on June 27, 1972, and again on July 10,
1974. The highest yearly average was 7.4 m in 1974; the lowest was 4.1, in
1971.
The Secchi disc data suggest an improvement in water transparency. The
proportion of measurements >5 m is higher for 1976/77 than for 1971-75. In
1977 the average summer Secchi disc reading was 6.3 m (SD 1.99, n = 7). The
DFW measured transparency biweekly in the summer of 1963; their average was
6.0 (SD = 2.60, n = 7). On July 18, 1961 they reported 11.6 m, the highest
value recorded, but that same year they also reported the lowest value, 1.8 m
on August 21.
Dissolved oxygen depletion occurs below 10 m in both summer and winter.
Values less than 5 mg/1 were recorded each summer at 13 m, with a low of 0.1
mg/1 on August 18, 1977 (Table 10). Lowest summer DO was recorded in either
July or August of each year except 1971 when 0.2 mg/1 was measured at 13 m on
September 1. September storms generally caused overturn and reoxygenated the
lower strata. Winter DO was measured under the ice on February 2, 1972 and
March 3, 1975. Bottom DO was very low in both cases, 0.5 and 1.5 mg/1, re-
spectively. Values <5 mg/1 extended as high as 10 m in July and August of
1971 and 1977 as well as in both winter samplings. Low DO in the hypolimnion
was apparent as early as 1946. In August of that year the DFW reported 4.8
and 0.3 mg DO/1 at 13.7 and 15.2 m, respectively (Locke, 1947).
Diamond Lake pH ranged from a high of 9.8 at the surface on June 4, 1971
to a low of 5.5 at 13 m on August 22, 1972. The highest value for any day
usually occurred between 4 and 7 m, while the lowest was at the bottom.
PRIMARY PRODUCERS
Algal cell counts from 1971 through 1973 can not be compared to 1974
through 1977 numbers because of different counting techniques (the latter per-
iod generating higher numbers). However, the pattern of phytoplankton numbers
24
-------
.32-
LU
§.24
tr
(NJ
tn
.16-
o
o:
2 .08
III
||
imi i .111 ii ii i Miii i iitii iinn i
1971 ' 1972 ' 1973 ' 1974 ' 1975 ! 1976 ' 1977
Figure 5. Total inorganic nitrogen volume weighted means.
-------
TABLE 9: TP AND TIN VOLUME WEIGHTED MEANS (MG/L)
TP
TIN
TP
TIN
TP
TIN
TP
TIN
TP
TIN
TP
TIN
TP
TIN
06/03
.048
.006
02/02
.034
.143
05/23
.021
06/05
.035
03/04
__
05/20
.023
.013
04/28
.06
.017
07/07
.036
.024
05/24
.042
.003
06/18
.021
.064
07/10
.013
06/05
.054
.056
06/29
.052
.017
06/02
.04
.012
1971
08/03
.054
.025
1972
06/29
.043
.014
1973
07/10
.024
.055
1974
08/07
.013
1975
07/09
.027
.011
1976
07/21
.050
.199
1977
06/15
.04
.014
09/01 09/27
.037 .133
.021 .019
07/24 08/22
.041 .047
.019 .035
08/14 09/11 10/18
.043 .042 .015
.389 .018 .058
09/12 10/09 12/03
.032 .042 .037
08/13 09/18 10/22
.019 .039 .048
.012 .025 .012
08/18 09/15 10/14
.034 .041 .030
.079 .024 .054
06/30 07/20 08/18 09/27 10/27
.04 .06 .08 .05 .04
.017 .029 .050 .111 .037
Annual
Average
.062
.019
.041
.043
.028
.117
.029
.037
.023
.038
.064
.051
.036
26
-------
ro
-xl
12.0-
o 9.0 H
UJ
cr
6.0-
o:
3.0-
1971 ' 1972 ' 1973 ' 1974 ' 1975 ' 1976 ' 1977
Figure 6. Secchi disc transparency.
-------
TABLE 10. DISSOLVED OXYGEN AT 13 M (MG/L)
ro
CO
Date
D.O.
Date
D.O.
Date
D.O.
Date
D.O.
Date
D.O.
Date
D.O.
Date
D.O.
06/03 07/07
9.9
1971
08/03
09/01 09/27
1.9
02/02 05/24
0.7
1972
06/29
0.2
7.8
07/24 08/22 09/25
0.5 5.3 5.0 2.6 7.6 7.8
1973
05/23 06/18 07/10 08/14 09/11 1Q/18
9.2 4.0 5.4 2.9 6.0 9.4
1974
06/05 07/10 08/07 09/12 10/09 12/03
8.6 4.9 4.0 — -- 10.5
1975
03/04 06/05 07/09 08/13 9/18 10/22
1.7 2.6 7.2 1.2 2.7 9.1
1976
05/20 06/29 07/21 08/18 09/15 10/14
8.3 8.4 0.3 5.0
1977
04/28 06/02 06/15 06/30 07/20 08/18 09/27
11.1 8.7 — 2.5 1.7 0.1 8.3
10/27
8.7
-------
ever the study period is similar to the TP curve (Figure 7). iota!
bers, averaged over each year, decreased from 1971 to 1973 and rose from 1974
to 1977, when the average reached approximately 9,000 cells/ml.
Initial samplings each year yielded relatively high counts, usually due
to an early bloom of the diatom, Asterionella formosa (Table 11). The highest
count of this species, 17,000 cells per ml, was recorded on June 4, 1971.
Almost exclusively Anabaena circinalis was the predominant blue-green
alga in Diamond Lake, generally reaching substantial numbers by July o^ August
and often the most numerous alga in September or October. Its earliest pre-
dominance was June 18, 1973, and it remained the most numerous alga for the
rest of that season. The highest density recorded for Anabaena was 12,000
cells/ml on August 18, 1977.
Green algae dominated the phytoplankton on only a few occasions. The
maximum concentration was 1200 cells/ml.
A Chrysophyte, Chromulina sp. , seemed to become much more significant in
the phytoplankton community after 1973, perhaps because of the change in
counting technique. Its maximum concentration was 8200 cells/ml on July 10,
1974. In about one-half of the post-1973 samplings Chromulina was the domi-
nant alga, including all of the 1977 samplings except August 18, when it was
second to Anabaena.
Maximum chlorophyll a (Chi a) was 39.8 mg/m3 on April 28, 1977. The
highest annual average, 14.0 mg/m3, also occurred that year. The lowest
annual average was 4.8 mg/m3 in 1973. The years 1976 and 1977 were unusual
compared to previous years because spring Chi a was high at the initial sam-
pling (Figure 8). Relatively high values at the end of the summer are char-
acteristic of all years. The plot of Chi a resembles the pattern of TP and
ohytoplankton numbers.
Summer Chi a and TP were positively correlated at the 0.05 level over the
whole study period. The average of pooled epilimnetic Chi a (not volume
weighted) from 1976/77 was significantly greater than the 1971-1975 period,
also at the 0.05 level, but 1976 alone is not significantly different from the
preceding period suggesting that it is a transition year (R. Vollenweider,
Senior Scientist, Canada Center for Inland Waters, pers. comm.).
Primary productivity (PP) peaked in 1973 with an annual average of 19.8
mg C fixed/m3/hr. It then decreased through 1976, suggesting a response to
the diversion. In 1977, however, a substantial increase again occurred (Fig-
ure 9). The highest PP was 31.3 mg C fixed/mVhr on September 11, 1973.
The distribution patterns of PP and Chi a are quite different. Primary
productivity, a rate function, is affected by many variables during the incu-
bation period while Chi a is essentially an instantaneous measurement, the
result of an integration of variables. Phytoplankton self-shading could
reduce PP and, correspondingly, the ratio of PP to Chi a. The species compo-
sition of the phytoplankton population could also affect the ratio as certain
species have relatively less Chi a than others.
29
-------
co
o
1000000-
IOOOOOH
1 20000-
oo 10000-
li 5000-j
LJ
O
1000-
500-
100-
L.
1971 ' 1972 ' 1973 ' 1974 ' 1975 r~!976 ' 1977
Figure 7. Total phytoplankton volume weighted means (horizontal bars indicate yearly means).
-------
TABLE 11. DOMINANT PHYTOPLANKTON AT CENTER STATION, VOLUME WEIGHTED MEANS
(EXPRESSED AS NUMBERS PER ML X 102)
1971
06/03 07/07 08/03 09/11
1972 1973
02/02 05/24 06/28 07/25 08/22 09/26 05/23 06/18 07/10 08/14 09/11 10/18
Anabaena
8.5
3.6 27 26
15 2.6 13 35 5.3
Anacystis
0.2
Ankistrodesmus
6.3
Asterionella
170 3.5
1.3 59 3.1
32
Chlamydomonas
Chromulina
Cryptomonas
0.3
0.5
Cyclotella
5.2
Dactylococcopsis
0.3
Dlnobryon cysts
Fraqllaria
0.6
0.7
Golenkinia
Heteromastix
Melosira
0.1
0.4
Nephroselmis
Ochromonas
Oocysti s
0.7
0.2
0.5
0.8
Rhodomonas
Schroederia
Sphaerocystls
0.5
0.1
0.3
Staurastrum
1.0
Stephanodlscus
5.2
0.4
1.1 1.7
Stlpicoccus
Synedra
0.1
3.9
1.2
1.2
Westell a
Green Flagellates 12 0.7 0.1 0.2
6.8
0.4
0.7
Unldent Flag's
Unldent Coccoids
Unknown
(Continued)
-------
Table 11. Continued
1974
06/05 07/10 08/07 09/12 10/09 12/04
1975 1976
03/03 06/05 07/09 08/13 09/18 10/15 05/20 06/30 07/21 08/17
Anabaena
10
8.4
12
3.2 2.2
42
Anacystls
Anklstrodesmus
Asterlpnella
2.2
25 130
22 41
13
Chlamydomonas
0.7 0.9
Chronul 1 na
82
0.6
11
5.1
3.5 2.1
20 43 12 21
Cryptomonas
1.1
6.2
1.5
Cyclotella
17
Oactylococcopsls
Dlnobryon cysts
3.4
5.1
Fragllari'a
oo
ro
GolenMnla
Heteromastix
12
Melosira
Nephroselmis
Ochromonas
3.4
0.8
0.5
0.7
Oocystis
1.7
Rhodomonas
3.6
0.6 1.7
0.6
Schroederla
Sphaerocystls
1.4
0.5
Staurastrun
Stephanodiscus
2.5
30
Stipoccus
Synedra
1.4
Westell a
1.2
Green Flagellates
0.2
Unldent Flag's
5.3
Urn'dent Coccoids
Unknown
14
(Continued)
-------
Table 11. Continued
1976 (Cont'd) 1977
09/15 10/14 04/28 06/02 06/29 07/20 08/18 09/28 10/27
Anabaena 30 40 20 120 30
Anacysti s
Anki strodesmus
Asterionella 92 0.8 0.4
Chlamydomonas
co Heteromastix
CO
10 12
Chroinulina 40 2 130 13 9 33 11 41 20
Cryptomonas 1.3
Cyclotella
Dactylococcopsls
Dinobryon cysts ______
Fragilarla ______
Golenkinia ______________
Melosira
Nephroselmis 3 0.5
Ochrononas
Oocystl s
Rhodoroonas
Schroederia
Sphaerocysti s
Staurastrum
Stephanodiscus 82
Stlplcoccus
Synedra
Westell a
Green Flagellates
Unident Flag's
Unldent Coccolds
Unknown
-------
48.0-H
36.0-
Q. 24.0
O
or
O
5 12.0
hllll Mill I INN Illll I I MM 1 INN Mill I
1971 ' 1972 ' 1973 ' 1974 ' 1975 ' 1976 ! 1977
Figure 8. Chlorophyll a^ volume weighted means.
-------
ro
oo
en
E
O 28
E
h-
>
h-
o
21-
14-
O
-------
A substantial part of the primary producer biomass was contained in the
aquatic vascular plants and macrophytic algae. Quantitative sampling was not
done but transect studies were conducted with SCUBA to determine the general
community structure. A well defined community was observed from approximately
2 to 8 meters, the transects showing three distinct bands. From approximately
2 to 4 m El odea canadensis was the dominant form. Potomogeton praelongis and
E. canadensis co-dominated between 4 and 6 m, the zone of maximum density,
while Nitella sp. dominated from 6 to 8 m.
BENTHIC MACROINVERTEBRATES
The sediments at the center station were typically flocculent, gray to
brownish organic silt. The peripheral station sediments were generally floc-
culent, light brown and often contained macrophytes.
Only those benthic macroinvertebrate samples collected continuously from
1971 through 1977 at the deep center station and three of the peripheral
stations are considered in this report (Figure 2). The coefficient of varia-
tion (CV) of total number of organisms for all samples (N = 515) was almost
38, ranging from 4 to 101 for each set of replicates. The CV for the center
station averaged 23 while the inshore stations averaged from 42 to 46. Data
from the peripheral stations in 1971 have not been included in the following
comparisons due to the small number of samples collected that year.
The temporal pattern of benthos population density was similar for all
four stations, a decrease to a low in 1974 followed by higher populations in
1976 and 1977 (Figure 10). Densities fluctuated greatly within single years.
The highest mean population, over 11,000/m2, was reached at the east shore
camp station in August, 1972. The lowest mean population, 450/m2 was col-
lected at the resort station in October, 1974. Yearly population means were
largest at the center station, never lower than 5700/m2.
Amphipods, chironomids, gastropods, leeches and oligochaetes comprised
the major faunal groups of the Diamond Lake benthos. Forty different taxa
were identified (Table 12). The predominant species and the percent composi-
tion of the major groups on a yearly basis are given in Table 13.
There were strong contrasts in predominant species between the center and
peripheral stations but little yearly temporal change in predominant species
within any one station. The midge, Chironomus decorus and the oligochaete,
Limnodrilus hoffmeisteri spiral is dominated the center station while along the
periphery the midge, Tanytarsus sp. , the leech, Holobdella stagnalis and the
amphipod, Hyallela azteca occurred most frequently. The relative percentages
of the major groups varied yearly at each station. While a change in group
proportions coincided with the 1974 population dip, composition in 1976 and
1977 tended to resemble that before 1974.
Richness and diversity values (Table 14) tend to be low for 1972 since
oligochaetes were not identified to species that year. Mean areal richness
decreased at the peripheral stations to a low in 1974 of 7 to 10 before peak-
ing in 1977 at over 14. The lowest value for the center station, about 4, was
reached in 1975. By 1977 richness had increased to the 1973 level of about 7.
36
-------
-v 50,000-
CD
LU
g 40,000-
OJ
S 1
> 30,000-
Z
6
CE
fj
< 20,000-
5
u
-y-
i- 10,000-
•z.
LlJ
oa
•M
IQ7I
1
1
Q
73
ill
j — .
1 IQ7"
1. 1 1C
1
7d '
IQ-
Center Station
i
III
M •
'K 1 IQ7K ' 1977
IM
^ 50,000-
co
UJ
CD 40,000-
LU
tr
LU
> 30,000-
z
0
cc
(J
< 20,000-
S
O
I
K 10,000-
z
UJ
m
Summer Home Station
|
•••• 1
illfl ttn mTl III
_ m
'
nl
1971 ' 197? ' 1973 ' 1974 ' 1975 ' 1976 ' 1977
^£
v 50,000-
QJ
s
m 40,000-
UJ
t-
(T
UJ
> 30,000-
5
< 20,000-
5
O
H 10,000-
z:
UJ
m
Resort Station
ill
rTTTi _^u TTm
1971 ' 1972 ' 1973 ' 1974 ' 1975 ' 1976
1
1
1 1977
i
11
i 84.239i
C\J r
v 50,000-
w
UJ
5
CD 40,000-
UJ
t—
tr
UJ
> 30,000-
6
o:
< 20,000-
^
o
K 10,000-
UJ
m
<.
|
111,255 J
^
Campground Station
\ ^" t™" "™" ""
•^t"* 111 If 1
hill rtn ,1. Ill 1 Hi 1
' 1971 ' 1972 ' 1973 ' 1974 ' 1975 ' 1976 ' 1977
Figure 10. Mean number benthic macroinvertebrates per square meter (horizontal bars indicate yearly means).
-------
TABLE 12. DIAMOND LAKE BENTHIC MACROINVERTEBRATES
Diptera
Ablabesmyia mom'1 is (Linnaeus)1
Chironomus decorus (= attenuatus of authors) group1
Cladotanytarsus Kieffer1
Cricotopus Wulp1
Cryptotendipes amachaerus (Townes)2
Dicrotendipes californicus Johannsen2
Glyptotendipes Kieffer (prob. G. lobiferus (Say))1
Pagastiella Brundin (prob. £. orophila (Edwards))1
Palpoymia Megerle group
Parachironomus abortivus (Mai loch) group2
Procladius culicifornris (prob. £. sublettei Roback) group1
Psectrocladius Kieffer*
Tanytarsus Wulp
Oligochaeta
Dero digitata (Muller)3
Ilyodrilus tempietoni (Southern)3
Limnodrilus hoffmeisteri spiral is Claparede3
Lumbriculus Grube
Naididae unidentified
Nais simplex Piguet
Pristina Ehrenberg
Sty!aria lacustris (Linnaeus)
Amphipoda
Crangonyx richmondensis occidental is Hubricht and Harrison4
Myall el a azteca (Saussure)
Hirudinea
Erpodellidae unidentified5
Glossiphonia complanata (Linnaeus)
Helobdella elongata (Castle)5
Helobdella stagnalis (Linnaeus)
Pelecypoda
Pisidium Pfeiffer
Gastropoda
Menetus opercularis Gould6
Physa Draparnaud
Valvata humeral is Say6
Trichoptera
Agray1ea Curtis
Oecetis inconspicua (Walker)
(Continued)
38
-------
Table 12 (Cont.)
Ephemeroptera
CaenIs Stephens
Callibaetis Eaton
Zygoptera
Coenagrlon Kirby
Ishnura Charpentier
Turbellaria
Hydracarina
Nematoda
1 Identified by J.E. Sublette, Eastern New Mexico Univ.
2 Identified by W. T. Mason, USEPA, Cincinnati
3 Identified by J.K. Hiltunen, USFWS
4 Identified by J.R. Holsinger, Old Dominion Univ.
5 Identified by D. J. Klemm, USEPA, Cincinnati
6 Identified by H. van der Schalie, Univ. Michigan
39
-------
TABLE 13. BENTHIC MACROINVERTEBRATE SUMMARY, 19/1-1977
1971
GrouP Mean %
No./m2
Amphipoda
Chironomidae 9,453 64.80
Gastropoda 2 0.01
Hirudinea 3 0.02
Oligochaeta 5,012 34.40
Others 114 0.80
Total 14,584
Predom. species a,i
Amphipoda
Chironomidae
Gastropoda
Hirudinea
Oligochaeta
Others
Total
Predom. species
1972
Mean
No./m2
3
3,894
3
4,677
32
8,609
a
1,510
14,451
284
1,308
727
520
18,800
k
%
0.03
45.20
0.03
54.30
0.4
,b
8.00
76.90
1.50
6.90
3.90
2.80
.e,J
1973
Mean %
No./m2
CENTER STATION
35 0.50
4,741 66.70
134 1.90
194 2.70
1,705 24.00
299 4.20
7,108
b » i » 9
RESORT STATION
982 44.70
443 20.10
44 2.00
579 26.40
46 2.10
103 4.70
2,197
f.e.k
1974
Mean
No./m2
5
4,038
4
34
1,516
118
5,715
b,
494
84
90
173
1
78
918
f
%
0.09
70.60
0.07
0.60
26.50
2.10
i,g
53.80
9.10
9.80
18.80
0.10
8.50
,e,c
1975
Mean
No./m2
11
3,681
4
12
2,346
39
6,093
661
365
622
286
36
347
2,317
%
0.18
60.40
0.06
0.20
38.50
0.64
b.i.g
28.50
15.80
26.80
12.30
1.50
15.50
f.h.e.k
1976
Mean
No./m2
20
7,643
7
133
4,012
90
11,905
b
1,295
4,847
437
435
54
448
7,516
k
%
0.17
64.20
0.59
1.10
33.70
0.76
,i,g
17.20
64.40
5.80
5.80
0.70
6.00
,f
1977
Mean
No./m2
17
16,153
6
46
1 1 ,886
89
28,197
1,053
4,869
257
704
857
590
8,330
%
0.06
57.30
0.02
0.16
42.10
0.30
b,g
12.60
58.40
3.10
8.40
10.30
7.10
k.j.f.e
SUMMER HOMES STATION
Amphipoda
Chironomidae
Gastropoda
Hirudinea
Oligochaeta
Others
Total
Predom. species
615
14,064
103
1,981
1,580
46
18,389
k
3.30
76.50
0.60
10.80
8.60
0.20
,e
940 21.20
1,589 35,80
700 15.70
909 20.50
153 3.40
147 3.30
4,438
k.d.f.e.h
266
274
367
731
45
74
1,757
e
15.10
15.60
20.90
41.60
2.60
4.20
,h,f ,k
278
1,595
358
915
56
206
3,408
8.10
46.80
10.50
26.80
1.60
6.00
d,e,h,k
59
9,341
411
1,144
133
172
11,260
k
0.50
82.90
3.60
10.10
1.20
1.50
,e
617
4,939
1,074
821
169
380
8,000
7.70
61.70
13.40
10.30
2.10
4.70
k,d,e,h
(Continued)
-------
TABLE 13. (Cont.)
1971
Group Mean %
No./m2
Amphipoda
Chironomidae
Gastropoda
Hirudinea
Oligochaeta
Others
Total
Predom. species
Predominant Species
a. Chironotnidae
b. Chironomus decorus
1972
Mean %
No./m2
1,336 2.80
41,096 85.90
351 0.70
3,814 8.00
1,136 2.40
97 0.20
47,830
k.e
1973
Mean %
No./m2
CAMPGROUND STATION
1,317 27.10
1,586 32.60
327 6.70
1,389 28.60
153 3.10
88 1 . 80
4,860
k.f.e
1974
Mean %
No./m2
897 44. 30
69 3.40
251 12.40
705 34.90
10 0.50
90 4.40
2,022
f,e,h
1975
Mean %
No./m2
631 14.50
2,190 50.60
418 9.60
890 20.50
74 1 . 70
125 2.90
4,328
k.e.f
1976
Mean %
No./m2
1,057 13.20
4,326 53.90
488 6.10
1,160 14.40
72 0.90
925 11.5
8,028
k.e.f
1977
Mean
No./m2
1,495
3,609
475
989
204
561
7,333
%
20.40
49.20
6.50
13.50
2.80
7.60
k.f.e
c. Crangonyx richmondensis occidentalis
d. Dicrotendipes californicus
e. Helobdella stagnalis
f. Hyallela azteca
g. Limnodrilus hoffmeisteri s|
h. Menetus opercularis
i. Oligochaeta
j. Pagastiella orophila
k. Tanytarsus
}iral is
-------
TABLE 14. BENTHIC MACROINVERTEBRATE AREAL SPECIES RICHNESS (SAR),
SHANNON-WEAVER DIVERSITY (H1) AND COMPLEMENT OF SIMPSON'S
INDEX (1-S)
1972*
SAR
H1
1-S
SAR
H1
1-S
SAR
H1
1-S
3.
0.
0.
10.
0.
0.
10.
0.
0.
051
057
046
822
595
587
810
518
540
1973
6.
0.
0.
9.
0.
0.
12.
0.
0.
806
424
495
356
640
646
598
711
692
1974
CENTER STATION
5.076
0.247
0.278
RESORT STATION
8.011
0.761
0.762
SUMMER HOME STATION
10.024
0.713
0.678
1975
4.
0.
0.
10.
0.
0.
10.
0.
0.
366
238
240
754
817
791
939
795
778
1976
5.
0.
0.
12.
0.
0.
11.
0.
0.
436
324
373
291
724
703
937
668
680
1977
7.
0.
0.
14.
0.
0.
14.
0.
0.
494
406
522
738
804
764
698
868
804
CAMPGROUND STATION
SAR
H1
1-S
11.
0.
0.
675
464
476
11.
0.
0.
013
552
574
7.577
0.550
0.621
9.
0.
0.
379
560
573
14.
0.
0.
264
813
762
14.
0.
0.
840
810
765
Oligochaetes not identified to species
42
-------
Shannon-Weaver diversity (H1) and the complement of Simpson's index (1 -
S.I.) were similar both in numerical value at the peripheral stations and in
temporal distribution at all four stations. The three peripheral stations did
not show a decrease in diversity corresponding to the population dip of 1974;
the center station, however, was lower in 1974 and 1975. There seemed to be a
general trend toward regaining or surpassing the 1973 levels for these indices
by 1977. Values for the latter year ranged from 0.4 to 0.5 for the center and
0.7 to 0.8 for the other stations.
The 1977 dendrogram (Figure 11) indicates two highly dissimilar groups in
the benthos (Bray-Curtis coeffcient of dissimilarity >0.8). The cluster on
the right is composed entirely of center station collections, and the large
group on the left is composed of the other stations with no clear pattern of
sub-grouping. Single dendrograms for the other years and a dendrogram utiliz-
ing all the collections from 1972 through 1977 were all very similar in ap-
pearance to Figure 11. The 1972-77 dendrogram indicates a possible tendency
toward some seasonal or yearly clustering.
This study has documented two aspects of the benthos of Diamond Lake:
that it is very diverse and that populations in the deeper part of the lake
are significantly different from those in the nearshore areas. Effects of the
diversion upon the benthic community are conjectural. However, there are
indications that few significant changes have taken place during the course of
this investigation. Had there been large temporal or spatial changes in
population composition or distribution, the clustering analyses should have
shown a much stronger tendency for the collections to group into more discrete
clusters. Predominant species were little changed at each station through
time. While there were some temporal fluctuations in percentage species
composition, perhaps due partly to predator-prey relationships coincident with
the 1974 population dip (as indicated by changes in the chironomid-leech
populations), composition in 1976 and 1977 was similar to pre-1974 levels.
Areal species richness declined with the population dip but was little changed
from previous levels at the end of the study. There were few changes in
species diversity, although yearly averages suggested an upward trend.
The amount of food available for benthic macroinvertebrate populations
from settled material would naturally be expected to be influenced by the
phytoplankton. The coincident decrease in benthos and phytoplankton in 1973
and 1974 in Diamond Lake may thus be related. The decrease in benthic popula-
tions in the mid-part of this study may also be part of larger or longer term
cyclic processes not evident by the extent of our investigation.
43
-------
1.0-
Q —
.8-
co .4-
co
0 .3-
.2-
I
2
3
4
Center Stn.
Resort Stn.
Summer Home Stn,
Campground Stn.
. R
CVj^C\jC\jC\jC\jC\j CVjCVj^CVjCXjCVi CSjfOCXjt^r^^CVjOgCViCXj.^frjCVjCVjOg
x\\\\\\ \\\\\\ \\\\\\\\\\\\\\x
i i i i i i i
^T to ro ro ro ro
-------
MANAGEMENT APPLICATIONS OF THIS RESEARCH
Meyerhoff (1977) found indications of recently accelerated eutrophication
in sediment cores from Diamond Lake. He attributed this acceleration to
increased human activity in the watershed which he assumed to begin about
1930. One of the projected benefits of the waste diversion system was to
ameliorate the impact of this still burgeoning activity. Reducing the nutri-
ent load was expected to result in an improved trophic state or at least a
reduced rate of eutrophication. Based on flushing rate and an approximation
of the sedimentation rate (Dillon and Rigler, 1975) Diamond Lake could be
expected to respond to the reduced loading after approximately 1-1.7 years.
The diversion was completed in December, 1975. Therefore, some change should
have been detectable in 1977, provided that the nutrient load had been altered
sufficiently. Calculations have shown that the probable maximum load reduc-
tion was only 10-15%. This would probably not noticeably affect the trophic
status of the lake. Fluctuations in natural loading and unpredictable sedi-
ment contributions could compensate for the reduction and continued leaching
of residual nutrients from sanitary drain fields could effectively reduce the
percentage diversion and delay lake response.
Our data suggest a relatively small cultural impact, even during recent
years when visitor use approached two orders of magnitude higher than that
reported in 1924. Diamond Lake appears to be quite productive as a result of
nutrient loading from natural sources. While the tributaries may occasionally
receive nutrients from human activities the impact seems to be minimal.
A major management concern is whether the lake can withstand additional
development without suffering accelerated eutrophication. Dillon and Rigler
(1975) developed an approach to making such a decision based on relationships
between nutrient loading and water quality characteristics. With a preconcep-
tion of the desired trophic state, in terms of water clarity and the type of
recreation to be promoted, a manager can use their system to estimate an
acceptable nutrient load. Methods for identifying the natural and artificial
components of the existing load are described which allow calculation of a
permissible increase (or a necessary decrease). The step-by-step system has
been applied to Diamond Lake (Table 15). Measurements from our seven-year
study were used instead of certain generalizations in the Dillon and Rigler
system.
Dillon and Rigler describe four classes of lakes based on maximum permis-
sible summer average Chi a level. With respect to the cold water fishery and
the high mean transparency, Diamond Lake fits the Level 1 category (cold water
fishery, mean Secchi disc ^5 m). However, the lake does not conform to per-
missible Chi a and the corresponding spring TP for this level (Tables 9, 15).
The permissible P for Level 1 would be about 1800 kg/yr (Table 15). With the
exception of 1974 the nutrient budget shows that the P from Silent and Short
45
-------
TABLE 15: ACCEPTABLE P LOAD AND CAPACITY FOR DEVELOPMENT
ACCORDING TO DILLON AND RIGLER (1975)
Step 1: Choose Maximum Permissible Summer Average Chi a
Level 1: 2 mg Chi a/m3; promoting body contact water recreation
cold water fishery desirable; high mean Secchi disc
transparency (> 5 m).
Level 2: 5 mg Chi a/m3; general water recreation; cold water
fishery not imperative; mean Secchi disc transparency
2-5 m.
Level 3: 10 mg Chi a/m3; body contact recreation not important;
emphasis on fishery (bass, bluegill); danger of fish
kill in winter due to oxygen depletion; Secchi disc
transparency 1-2 m.
Level 4: 25 mg Chi a/m3; suitable only for warmwater fishery;
considerable danger of fish kill; Secchi disc trans-
parency < 1.5m.
Step 2: Calculate Permissible Spring Phosphorus Concentration
Iog10 [P] = Oog10 [Chi a] + 1.14)/1.45
Level 1: 9.9 mg P/m3
2: 18.5 mg P/m3
3: 29.9 mg P/m3
4: 56.3 mg P/m3
Step 3: Determine Lake Surface Area (A in m2), mean depth (z in m)
and Volume (V in m3).
A = 1.243 x 107 m2
o
z = 7.2 m
V = 9.02 x 107 m3
Step 4: Determine Area of Watershed (Ad in m2)
A. = 1.42 x 108 m2 - 1.24 x 107 m2
a = 1.296 x 108 m2
Step 5: Determine total annual runoff for watershed (m3/yr/m2)
Unnecessary for Diamond Lake
(Continued)
46
-------
TABLE 15. (Cont.)
Step 6: Determine total outflow volume Q (m3/yr)
Measured avg. 1972-1977 = 6.14 x 107 m3/yr
and Flushing Rate p = Q/V (yr-1)
(6.14 x 107 m3/yr)/(9.02 x 107 m3) = 0.68/yr
Step 7: Calculate the Areal Water Load, q (m/yr)
qs = Q/AQ
= (6.14 x 107 m3/yr)/1.243 x 107 m2
=4.94 m/yr
Step 8: Calculate the Retention Coefficient (R)
R = 0.426 exp (-0.271 qg) + 0.574 exp (-0.00949 qg)
= 0.6594
Step 9: Calculate the Response Time to a Change in Loading
Response Time =(3^5) 0.69/(p + 10/z)
= 1.0 -> 1.7 yr
Step 10: Calculate the Permissible Phosphorus load, L m (mg/m2/yr).
Lpem, = (CP] • l ' P)/(1-R)
Level 1: = (9.9 x 7.2 x 0.68)/(l-.6594) = 142.3 mg/m2/yr
Level 2: = (18.5 x 7.2 x 0.68)/(1-.6594) = 265.9
Level 3: = (29.9 x 7.2 x 0.68)/(l-.6594) = 429.8
Level 4: = (56.3 x 7.2 x 0.68)/(l-.6594) - 809.3
and the Permissible Supply, Jperm (kg/yr)
J = (L .A )/106
perm v perm o
Level 1: =1767 kg/yr
Level 2: = 3305
Level 3: = 5342
Level 4: = 10,060
Step 11: Determine the Phosphorus Supply from the Land
(from nutrient budget, Silent Cr., Short Cr. and Intermittent Str.)
JE = 2164 kg/yr ____
(Continued)
47
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TABLE 15. (Cont.)
and the Load
LE= JE/Ao=24.0
(Groundwater contributed approximately 266 kg/yr in addition
to the above)
Step 12: Determine the Phosphorus Supply from Precipitation (from
nutrient budget)
JpR = 114 kg/yr
Step 13: If the Natural Supply, J , is greater than or equal to the
Permissible Supply, J n, allow no further development.
JM = ^c + JDD (+ Groundwater Supply)
ii t r K
= (2164 + 114 + 266) kg/yr
= 2544 kg/yr
(Greater than Level 1 but less than Level 2)
Step 14: Determine the Present Number of Cottages, N , and Permanent
Dwellings, NQ.
N = 102 Recreation Residences (Cottages)
ND = 0 (all facilities on east shore are on interceptor line)
and calculate the number of capita years per year at the lake, Npy.
Average (1969-77) Visitor Days to Summer Homes
= 29,200/yr (12 hr days)
NpY = 54 ca. yrs/yr
Step 15: Calculate the Phosphorus Supplied to the lake from the Cottage
Units (Artificial Supply, J.).
J = (0.8 kg/ca.yr) (Ncy)
= 43 kg/yr
Step 15: Calculate the Present Total Supply of Phosphorus, JT.
= 2544 kg/yr + 43 kg/yr
= 2587 kg/yr
(Still less than J erm = 3305 kg/yr)
(Continued)
48
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TABLE 15. (Cont.)
Step 17: Calculate the Total Permissible Number of Cottages, N m
V™ = (Jpe™ - JN)/0.53x0.8
= 1795 (for level 2)
Step 18: Calculate the Additional Number of Cottages, N . .
Nadd = Nperm " Nc
= 1693 (for level 2)
49
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Creeks exceeds this allowable limit. The yearly supply from all measured
natural sources averaged over 2500 kg indicates that Level 1 cannot be main-
tained. It should be noted that the transparency sometimes remained greater
than 5 m even during rather heavy blue-green algal blooms as a result of algal
clumping. Also, the cold water fishery is supplemented through intensive
management by the DFW. Provision for such an intensive management program is
not made by Dillon and Rigler.
Level 2 is described as having maximum summer average Chi a of 5 mg/m3
and an average Secchi disc transparency of 2-5 m. A cold water fishery is not
characteristic of a Level 2 lake (Table 15). Diamond Lake still exceeds the
desired Chi a average. The average summer (June-Sept.) values over the study
period were between 5 and 10 mg/m3, corresponding to Level 3. It seems,
however, that, the most desirable status consistent with recreational demands
is Level 2. The present degree of productivity is essential in maintaining
the large population of rapidly growing trout. Substantially reducing the
primary productivity would probably adversely affect the fishery and reduce
the attraction of the lake. Allowing the lake to assume Level 3 status would
be even less desirable because the greater productivity would probably result
in seasonal fish kills due to low DO and an increase in blue-green algal
blooms.
Vollenweider (1976) suggested from data gathered from a large number and
variety of lakes that the "loading tolerance" of a lake can be determined if
the hydraulic load (total yearly water discharge divided by the lake surface
area) and the mean depth are known. Using his relationship the critical
loading for Diamond Lake is calculated to be approximately 1350 kg P/yr (Table
16). At this rate the lake could probably maintain oligotrophic characteris-
tics. Loading in excess of about twice this amount would result in a eutro-
phic system. This is more restrictive than the Dillon and Rigler projections,
suggesting that the trophic status of Diamond Lake might be even more vulner-
able.
TABLE 16: CRITICAL PHOSPHORUS LOAD ACCORDING TO VOLLENWEIDER (1975)
Lr (mgP/m2/yr) = 10 (z Q/V)(1 + V~V70~)
c y y
L = critical loading level in P controlled lake
z = mean depth (Diamond Lake [DL] = 7.2 m)
Q = yearly outflow (DL = 6.145 x 107 m3)
V = Volume of lake (DL = 9.02 x 107 m3)
L = 108.5 mg P/m2/yr
c = 1349 kg P/yr (for Diamond Lake)
Bortleson et aj. (1974) developed a system for rating the trophic condi-
tion and the potential for eutrophication of lakes and reservoirs in the State
of Washington, taking into account various physical and water quality charac-
teristics and cultural influences. Table 17 shows that with this system,
50
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TABLE 17. RATING OF FACTORS AFFECTING PRESENT AND POTENTIAL TROPHIC STATUS
ACCORDING TO BORTLESON (1974)
Physical Factors Value
Mean depth (m) 7.2
Water volume 90.2
(hm3)
Bottom slope (%) 0.36
Shoreline 1.19
Configuration
Ratio of drainage 1.57
area to lake
volume (mVm3)
Altitude (m) 1580
Water renewal 1 . 37
time (yrs)
Rating Notes Cultural Factors Value
3 Point Sources of 0
Domestic Sewage
1 Nonpoint Sources 200
(kg TP per Km2 of
lake per year)
5 Volume of water 0.88
per nearshore
home (hm3)
2 % nearshore land 21
developed for
residential use
3
1
3 includes
ground-
water
Rating Notes Water Quality Value
Factors
1 TP upper water 38
(pg/1)
2 from nu- TP ratio, bottom 2.6
trient to upper water
budget
2 not full TIN upper water 38
year resi- (ug/1)
dences
3 not full TIN ratio, bottom 3.1
year resi- to upper water
dences
Organic N, upper 345
water (ug/1)
Specific Conduc- 25-30
tance (umhos at
25°C)
Secchi disc (m) 6. 1
DO near bottom 3.6
(mg/1)
Water temperature 12.6
near bottom (°C)
X lake surface in 1-10
emergent, rooted
aquatic plants
X shoreline in < 10
emergent, rooted
aquatic plants
Rati ng Notes
5 0-10 m; not
vol. wtd;
'71-77 avg.
3
1 0-10 m; not
vol. wtd7^"71-77
avg excl. 8/14/73,
5m, 697 ug/1
4
3 0-10 m; not vol.
wtd; '71-77 avg.
2
2 '71-77 avg.
3 13 m; 6/15-9/15;
'72-77 avg.
4 13 m; 6/15-9/15;
'72-77 avg.
2 estimate
1 estimate
-------
Diamond Lake is of an intermediate trophic status. Barring a substantial
change in cultural influence the lake should remain stable.
The three evaluations have important management implications. The natu-
ral nutrient loading precludes an oligotrophic system. It is unlikely that
oligotrophy would be the management objective but minimizing the cultural
influence would help maintain the lake's present status. This would include
control of land disturbance and soil erosion. Pearl and Goldman (1972) and
Goldman (1974) have demonstrated that trophic status can be affected by in-
creased erosion and siltation. Terrestrial wildlife, human health and aes-
thetics should also be considered.
As part of a lake management plan it is extremely important that water
quality/nutrient supply relationships be defined. A nutrient budget with its
concomitant hydrologic information is vital to this understanding. "Point"
sources of nutrients need to be quantified to assess artificial or cultural
impact. An acceptable nutrient supply could be estimated if, additionally,
the lake surface area and volume are known.
Nutrient loading from non-point sources can be estimated if funds and/or
time limitations prevent actual field measurements. Land use type/stream
nutrient concentration regressions (Omernik, 1977) together with flow data can
provide an estimate of loading from a watershed. These flow data are reported
annually in the USGS Water Resources Data publication for each state. Flow
data from a specific stream not included in the report could be extrapolated
from another gaged stream if watersheds are similar and drainage areas are
known. For most accurate extrapolation, one should consider proximity, alti-
tude and exposure (N, S, E, W). Rainfall isolines (NOAA, 1974) would help
identify a proper watershed for extrapolation purposes.
Table 18 illustrates the use of estimations rather than actual field
values when applying the Dillon and Rigler and Vollenweider critical loading
calculations to Diamond Lake. Only two field measurements were used, maximum
depth and the number of summer homes. These calculations indicate that for an
oligotrophic system loadings of 2825 kg P/yr (Dillon and Rigler) and 2382 kg
P/yr (Vollenweider) are acceptable. However, calculations based on actual
measurements (Tables 15 and 16) indicate that these numbers are far too high.
The factor most responsible for this discrepancy is the outflow volume (Q).
The estimate used in Table 18 is over twice the measured flow which doubles
the calculated flushing rate, thereby increasing the "permissible" nutrient
supply. The value of precise field measurements is evident.
52
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TABLE 18. DETERMINING ACCEPTABLE P LOAD WITH A MINIMUM OF
FIELD MEASUREMENTS
Dillon and Rigler
Step 1: See Table 15
Step 2: See Table 15
Step 3: A = 1.216 x 107 m2 (from USGS, 1:62,500, Diamond Lake, Oreg. , 1956)
V = 1/2 A x Z _ (H. Mercier, personal comm. 10/27/78)
0 max
= 8.69 x 107 m3 (Z obtained by measurement)
max
Equation assumes the cross-sectional area to be a linear function
of depth. It appears to work well for basins with a regular shape.
A contour map should be made for irregular basins.
Z =
= 7.1 m
Step 4: A. = 1.447 x 108 m2 - 1.216 x 107 m2 = 1 . 325 x 108 m2 (from USGS,
T: 62, 500, Diamond Lake, Oregon, 1956)
Step 5: r = 4.409 x 108 m3/440 km2 • yr
= 1.00 mVm2 yr (USGS, 1971-77, North Umpqua River below Lemolo
Lake, average discharge, cal. years 1970-76)
The drainage area for this gage is on the same rainfall isoline
as Diamond Lake and actually includes the Diamond Lake watershed.
Step 6: Q = A . • r
= (T.325 x 108 m2) (1.00 m3/m2 yr)
= 1.325 x 108 mVyr
p = Q/V
= (1.325 x 108 m3/yr)/(8.69 x 107 m3)
=1.52 yr-1
Step 7: q =
s = (l.§25 x 108 m3/yr)/(1.216 x 107 m2)
= 10.90 m/yr
Step 8: R = 0.426 exp (-0.271 q ) + 0.574 exp (-0.00949 q )
= 0.540
Step 9: Response Time =(3^5) 0.69/(p + 10/z)
= 0.7 -> 1.2 yr
(Continued)
53
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TABLE 18. (Cont.)
Step 10: L = ([P] • z - p)/(l-R)
Level 1: 232.3
Level 2: 434.0
Level 3: 701.5
Level 4: 1320.8
J = (L -A )/106
perm ^ perm cr
Level 1: 2825 kg
Level 2: 5277
Level 3: 8530
Level 4: 16,061
Step 11: (from Omernik, 1977, p. 55)
No Agriculture
"» 5% urban area in intermittent stream watersheds (4.350 x 107 m2)
[P] = 0.032 mg/1
E! = (0.032 mg/l)(1000 l/m2/yr) = 32.0 mg/m2/yr
No urban area in remainder of watersheds (8.900 x 107 m2)
[P] = 0.028 mg/1
E2 = 28.0 mg/m2/yr
M]> + (Ad2>
= 1.392 x 109 mg/yr + 2.492 x 109 mg/yr
= 3884 kg/yr
LE = JE/Ao
= 319.4 mg/m2/yr
Step 12: 5 ug TP/1 in precipitation at Waldo Lake, OR (Malueg et al_. , 1972)
Average Annual Precipitation near Diamond Lake
•v 24 inches/yr (NOAA, 1974)
J = (0.61 m/yr)(A = 1.243 x 107m2)(5 mg/m3)
PK * 38 Kg/yr
Step 13: JN = JE + JpR
= 3922 kg/yr
LN = LE + LPR
= 322.5 mg/m2 yr
CA (Continued)
-------
TABLE 18. (Cont.)
Step 14: N = 102
N = (0.69)(102)
LY = 70
Step 15: J. = (0.8) NpY
M = 56 kg/yF
Step 16: JT = JN + JA
= 3978 kg/yr
= 2455 (for level 2)
Step 18: Nadd = Nperm - NC
= 2353 (for level 2)
Vollenweider
\_ = 10 (z Q /V)(l +
c y j
= 10 (7.1)(1.325 x 108)(1 + V8.69 x 10V1.325 x 10° )/(8.69 x 107)
= 195.9 mgP/m2/yr
= 2382 kg P/yr (for Diamond Lake)
55
-------
REFERENCES
Adams, C.F. 1975. Nutritive value of American foods in common units. Agri-
cultural Handbook #456, Agricultural Research Series, U.S. Department of
Agriculture, 291 p.
American Public Health Association. 1971. Standard methods for the examina-
tion of water and wastewater. 13th Ed. 874 p.
Bauer, J.A. 1976. Diamond Lake range management. Oregon Wildlife 31(11):
3-5.
Boesch, D.F. 1977. Application of numerical classification in ecological
investigations of water pollution. U.S. Environmental Protection Agency.
Ecol. Res. Ser. EPA-600/3-77-033.
Bortleson, G.C., N.P. Dion and J.B. McConnel. 1974. A method for the rela-
tive classification of lakes in the State of Washington from reconnais-
sance data. U.S. Geological Survey, Water Resources Investigations
37-74, 38 p.
Burgess, F.J. 1966. An evaluation of waste collection and treatment needs at
Diamond Lake, Oregon. Consultant Report to U.S. Forest Service, 18 p.
Cleator, F.W. 1924. Report on Diamond Lake recreation unit, Umpqua National
Forest. Cleator and Johnson's Recreation Surveys, 5 p.
DeMarte, J.A. and R.T. Hartman. 1974. Studies on absorption of 32P, 59Fe and
45Ca by water milfoil (Myriophyllum exalbescens Fernald). Ecology 55:
188-194.
Dillon, P.J. and F.H. Rigler. 1975. A simple method
capacity of a lake for development based on lake
Fish. Res. Bd. of Canada 32(9):1519-1531.
for predicting the
trophic status. J.
Goldman, C.R., E. Steemann Nielson, R.A. Vollenweider and R.G. Wetzel. 1971.
The 14C light and dark bottle technique, p. 70-73. In R.A. Vollenweider
(ed ) A manual on methods for measuring primary production in aquatic
environments. IBP Handbook No. 12, Blackwell Scientific Publications,
Oxford (G.B.).
1974. Eutrophication of Lake Tahoe emphasizing water quality.
U.S. Environmental Protection Agency. Ecol. Res. Ser. EPA-660/3-74-034.
Greene, J.C., W.E. Miller, T. Shiroyama, R.A. Soltero and K. Putnam. 1976.
Use of laboratory cultures of Selenastrum, Anabaena and the indigenous
56
-------
isolate Sphaerocystls to predict effects of nutrient and zinc interac-
tions upon phytoplankton growth in Long Lake, Washington. Mitt. Int.
Ver. Limnol. 21:372-384.
Hughes, D.R. 1970. Lake Creek water quality monitoring station, a progress
report. US Forest Service, Umpqua National Forest, 13 p.
Hurlbert, S.H. 1971. The nonconcept of species diversity: A critique and
alternative parameters. Ecology 52:577-586.
Hutchinson, G.E. 1957. A treatise on limnology. Vo. 1. Geography, physics
and chemistry. John Wiley and Sons, Inc. NY. 1015 p.
Larsen, D.P., D.W. Schults and K.W. Malueg. 1978. Summer internal phosphorus
supplies in Shagawa Lake, Minnesota. U.S. Environmental Protecton Agen-
cy. Manuscript.
Locke, F.E. 1947. A preliminary report on the Diamond Lake study. Oregon
State Game Commission, 21 p.
Lund, J.W.G., C. Kipling and E.D. LeCren. 1958. The inverted microscope
method of estimating algal numbers and the statistical basis of estima-
tions by counting. Hydrobiologia 11:143-170.
Malueg, K.W., J.R. Tilstra, D.W. Schults andC.F. Powers. 1972. Limnological
observations on an ultraoligotrophic lake in Oregon, U.S.A. Verh. Inter-
nat. Verein. Limnol., 18:292-302.
McHugh, R.A. 1972. An interim study of some physical, chemical and biologi-
cal properties of selected Oregon Lakes. Oregon Department of Environ-
mental Quality, p. 62-66.
Mclntosh, R.P. 1967. An index of diversity and the relation of certain
concepts to diversity. Ecology 48:392-404.
McRoy, C.P., R.I. Barsdate and M. Nebert. 1972. Phosphorus cycling in an
eelgrass (Zostera marina L.) ecosystem. Limnol. & Ocean., 17(l):58-67.
Meyerhoff, R.D. 1977. Sediment characteristics and the trophic status of
four Oregon lakes. M.S. Thesis, Oregon State University, Corvallis, OR,
74 p.
Miller, W.E., T.E. Maloney and J.C. Greene. 1974. Algal productivity in 49
lake waters as determined by algal assays. Water Res. 8:667-679.
, j.c. Greene and T. Shiroyama. 1976. Application of algal assays
to define the effects of wastewater effluents upon algal growth in multi-
ple use river systems. In E.J. Middlebrooks, D.A. Falkenborg and T.E.
Maloney (eds.), Biostimulation and nutrient assessment. Ann Arbor Sci-
ence, p 77-92.
57
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National Oceanic and Atmospheric Administration. 1974. Climates of the
States. Vol. I & II, U.S. Dept. Commerce.
Omernik, J.M. 1977. Nonpoint source-stream nutrient level relationships: A
nationwide study. U.S. Environmental Protection Agency. Ecol. Res. Ser.
EPA-600/3-77-105. 151 p.
Oregon State Game Commission. 1947-1977. Diamond Lake investigations.
Annual reports.
Pearl, H.W. and C.R. Goldman. 1972. Stimulation of heterotrophic and auto-
trophic activities of a planktonic microbial community by siltation at
Lake Tahoe, California. Mem. 1st. Ital. Idrobiol. 29 Suppl.:129-147.
Purdom, B. 1964. The geologic history of the Diamond Lake area. U.S. Forest
Service and Douglas County parks Dept. 39 p.
Pielou, E.C. 1970. An introduction to mathematical ecology. Wiley - Inter-
science, New York, NY, 286 p.
Robertshaw, N.F. and L.M. Thorpe. 1965. Diamond Lake recreation area plan--
Umpqua National Forest. U.S. Forest Service.
Sanville, W.D. and C.F. Powers. 1971. Diamond Lake studies--1971. Progress
report No. 1. Working Paper No. 8, U.S. Environmental Protection Agency.
22 p.
Schindler, D.W., H. Kling, R.V. Schmidt, J. Prokopowich, V.E. Frost, R.A. Reid
and M. Capel. 1973. Eutrophication of lake 227 by addition of phosphate
and nitrate: The second, third and fourth years of enrichment, 1970,
1971 and 1972. J. Fish. Res. Bd. Canada 30(10):1415-1440.
Shiroyama, T. Unpublished algal assay data from Diamond Lake, Oregon.
Simpson, E.H. 1949. Measurement of diversity. Nature 163:68.
Strickland, J.D.H. and T.R. Parsons. 1965. A manual of seawater analysis.
Bull. Fish. Res. Bd. Canada, 125 p.
Swartz, R.C. 1978. Techniques for sampling and analyzing the marine macro-
benthos. U.S. Environmental Protection Agency. Ecol. Res. Ser. EPA-600/
3-78-030. 26 p.
U.S. Forest Service. 1970. Diamond Lake recreation management composite
plan.
U.S. Environmental Protection Agency. 1971. Methods for chemical analysis of
water and wastes. Water Quality Office. Analytical Quality Control
Laboratory, Cincinnati, OH. 312 p.
U.S. Environmental Protection Agency. 1973. Biological field and laboratory
methods for measuring the quality of surface waters and effluents.
58
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Weber, C.I. (ed.), U.S. Environmental Protection Agency, Environ. Mon.
Ser. EPA-670/4-73-001, 180 p.
U.S. Environmental Protection Agency. 1978. Report on Diamond Lake, Douglas
County, OR, EPA Region X. Working Paper No. 828, 21 p.
Vollenweider, R.A. 1976. Advances in defining critical loading levels for
phosphorus in lake eutrophication. Mem. 1st. Ital. Idrobiol. 33:53-83.
59
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TECHNICAL REPORT DATA
(Please read Instructions on the rt verse before co;np!<: ling)
REPORT NO.
EPA-600/8-79-017a
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
5. REPORT DAT.r;
The Effects of Decreased Nutrient Loading on the
Limnology of Diamond Lake, Oregon
June 1979 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
W.L. Lauer, G.S. Schuytema, W.D. Sanville
F.S. Stay, C.F. Powers
PERFORMING ORGANIZATION NAME AND ADDRESS
Environmental Research Laboratory—Corvallis, OR
Office of Research and Development
Environmental Protection Agency
Corvallis, OR 97330
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
same
13. TYPE OF REPORT AND PERIOD COVERED
final - inhouse 1971-1977
14 SPONSORING AGENCY CODE
EPA/600/02
15. SUPPLEMENTARY NOTES
An Appendix report (EPA-600/8-79-017b) is available from the National Technical
Information Service, Springfield, VA 22161
16. ABSTRACT
Responding to accelerated recreational pressure at Diamond Lake, Oregon, in 1969 the
U.S. Forest Service began installation of a wastewater diversion system which would
eventually carry 85 to 90% of the sewage out of the watershed. From 1971 through
1977 the U.S. Environmental Protection Agency conducted a program of research on the
lake to determine its trophic status and identify changes that might be the result of
the diversion.
The lake is quite productive as the result of natural loading from tributaries,
groundwater and bottom sediments. Cultural influence, initially speculated to be
significant was discovered to have a relatively minor impact on the lake. Total
phosphorus and chlorphyll a_ levels reached a low in 1973, but by 1977 had increased
to levels comparable to 1971. Species composition of the benthic macroinvertebrate
population was the same in 1976/1977 as it was at the beginning of the study.
Recommendations include an adaptation of the Dillon and Rigler system for determining
the development capacity of lakes.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI 1-icld/Group
limnology
lakes
water pollution
hydrology
wastewater diversion
phosphorus
chlorophyll a_
nutrient loading
eutrophication
08/H
18. DISTRIBUTION STATEMENT
Release to public
19. SECURITY CLASS (This Report)
unclassi ned
21. NO. OF PAGES
68
20. SECURITY CLASS I This page j
unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION is OBSOLETE
60
irGPO 699-32!
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