WATER POLLUTION CONTROL RESEARCH SERIES • 16010 DNY 07/71
EUTROPHICATION OF SURFACE
WATERS-LAKE TAHOE
INDIAN CREEK RESERVOIR
U.S. ENVIRONMENTAL PROTECTION AGENCY
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WATER POLLUTION CONTROL RESEARCH SERIES
The Water Pollution Control Research Series describes the
results and progress in the control and abatement of pollution
in our Nation's waters. They provide a central source of
information on the research, development and demonstration
activities in the Environmental Protection Agency, through
inhouse research and grants and contracts with Federal,
State, and local agencies, research institutions, and
industrial organizations.
Inquiries pertaining to Water Pollution Control Research
Reports should be directed to the Chief, Publications Branch
(Water), Research Information Division, R&M, Environmental
Protection Agency, Washington, D.C. 20^60..
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EUTROPHICATION OF SURFACE WATERS - LAKE TAHOE
INDIAN CREEK RESERVOIR
Lake Tahoe Area Council
South Lake Tahoe, Calif., 95705
for the
ENVIRONMENTAL PROTECTION AGENCY
Project Nos. 16010 DNY
16010 DSW
July 1971
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EPA Review Notice
This report has been reviewed by the Water
Quality Office, EPA, and approved for publication.
Approval does not signify that the contents
necessarily reflect the views and policies of
the Environmental Protection Agency, nor does
mention of trade names or commercial products
constitute endorsement or recommendation for
use.
For sale by tho Superintendent of Documents, U.S. Government Printing Ollice, Washington, D.C. 20402 - Price tl.ss
11
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ABSTRACT
During the years 19^9 "to 1971 field and laboratory studies were made to determine
the temporal changes and relationships between the water quality characteristics
of Indian Creek Reservoir and those of reclaimed water from the South Tahoe Public
Utility District, which comprised 70 percent of the annual input to the reservoir.
Reclaimed water contained 0.01 to 0,0k mg/,0 phosphorus and more than 15 mg/,0
ammonia. Initially the reservoir would not support fish life, but as the reservoir
matured, ammonia levels declined to less than k mg/£ and by 1970 the reservoir was
an excellent trout fishery. Approximately 70 percent of the ammonia nitrogen was
lost to the atmosphere by nitrification-denitrification in the system. Good bio-
logical productivity of the reservoir indicated access to other sources of
phosphorus, probably soil and surface runoff.
Bioassays showed the growth stimulating ability of the reservoir water to exceed
that of the reclaimed water. Various parameters showed that the reservoir responds
to more complex factors than those measurable in the reclaimed waste water, thus
raising the question of the optimum degree of treatment of water destined for
recreational impoundments.
This report was submitted in fulfillment of Demonstration Grants No. 16010 DSW and
16010 DNY under the sponsorship of the Water Quality Office, Environmental
Protection Agency.
iii
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CONTENTS
Section
I
II
III
IV
V
VI
VII
VIII
IX
X
XI
Conclusions
Recommendations
Introduction
Project Design and Methodology
Results of Study
Physical Observations
Chemical Observations
Biological Observations
Discussion and Evaluation of Results
Acknowledgment s
References
Publications and Patents
Glossary
Appendix
1
5
7
13
21
21
29
52
73
77
79
81
83
85
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FIGURES
PAGE
1 GEOGRAPHICAL RELATIONSHIPS, INDIAN CREEK RESERVOIR AND EXPORT
LINE FROM LAKE TAHOE BASIN 9
2 LOCATION OF SAMPLING STATIONS AT INDIAN CREEK RESERVOIR l1^
3 CLARITY OF INDIAN CREEK RESERVOIR, (SECCHI DISK) 28
k VARIATION IN SURFACE WATER TEMPERATURE (TOP 1/2 METER),
INDIAN CREEK RESERVOIR 28
5 VARIATION IN COD, INDIAN CREEK RESERVOIR 30
6 CLARITY OF WATER (SECCHI DISK) AS A FUNCTION OF SUSPENDED SOLIDS 31
7 VARIATION IN SUSPENDED SOLIDS, INDIAN CREEK RESERVOIR 32
8 VARIATION IN VOLATILE SUSPENDED SOLIDS, INDIAN CREEK RESERVOIR 32
9 VARIATION IN IRON CONCENTRATION, INDIAN CREEK RESERVOIR 3]<-
10 VARIATION IN CHLORIDE CONCENTRATION, INDIAN CREEK RESERVOIR 3^
11 VARIATION IN pH, INDIAN CREEK RESERVOIR 36
12 VARIATION IN CONDUCTIVITY, INDIAN CREEK RESERVOIR 36
13 VARIATION IN CALCIUM CONCENTRATION, INDIAN CREEK RESERVOIR 38
ik VARIATION IN ALKALINITY, INDIAN CREEK RESERVOIR 38
15 VARIATION IN INORGANIC CARBON, INDIAN CREEK RESERVOIR ^0
16 VARIATION IN CONCENTRATION OF ORTHOPHOSPHATE, INDIAN CREEK
RESERVOIR ^0
17 VARIATION IN CONCENTRATION OF TOTAL PHOSPHORUS, INDIAN
CREEK RESERVOIR ^2
18 VARIATION IN CONCENTRATION OF ORGANIC NITROGEN, INDIAN
CREEK RESERVOIR k2
19 VARIATION IN CONCENTRATION OF AMMONIA, INDIAN CREEK RESERVOIR ^3
20 VARIATION IN CONCENTRATION OF NITRATE + NITRITE NITROGEN,
INDIAN CREEK RESERVOIR ^3
21 VARIATION IN CONCENTRATION OF TOTAL NITROGEN, INDIAN CREEK
RESERVOIR ^5
22 VARIATION IN DISSOLVED OXYGEN, INDIAN CREEK RESERVOIR ^5
23 DISSOLVED OXYGEN INCREASE BY VASCULAR PLANTS 66
2k VARIATION IN NITRIFICATION RATE, DISSOLVED OXYGEN, AND
TEMPERATURE WITH DEPTH, INDIAN CREEK RESERVOIR, AUGUST 1970 67
25 MAXIMUM SPECIFIC GROWTH RATE, £b FOR UNDILUTED SAMPLES
FROM INDIAN CREEK RESERVOIR SYSTEM 71
vi
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TABLES
Mo. Pa
1 Summary of Reclaimed Water Inputs to Indian Creek Beservoir 22
2 Water Budget, Indian Creek Reservoir 2J
3 Weekly Observations of Environmental Data, Indian Creek
Reservoir 25
k Summary of Changes in Nutrient Concentration, Indian Creek
Reservoir 39
5 Inventory of Selected Parameters of Indian Creek Reservoir ^6
6 Benthic and Soil Sample Analysis at Indian Creek Reservoir 50
7 Estimated Nutrient Balance 51
8 Summary of Benthic Organisms Collected from Indian Creek
Reservoir by use of Ekman Dredge 55
9 Survey of Organisms Observed in Microscopic Surveys of
Indian Creek Reservoir 57
10 Summary of Creel Census Results for Opening Weekend of
Fishing Season at Indian Creek Reservoir, 1970 and 1971 6k
11 Estimate of Vascular Aquatic Plant Standing Crop in Indian
Creek Reservoir, 1970 65
12 Estimates of Rates of Ammonia Oxidation and of Denitrification
of Nitrates in Indian Creek Reservoir as of August 1970 69
vii
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SECTION I
CONCLUSIONS
Based on the results of physical, chemical, and biological observations of Indian
Creek Reservoir during the period March 1969 to May 1971> the following conclusions
and evaluations are made.
1. The water impounded at Indian Creek Reservoir during the period of study was
approximately one-third surface runoff and direct precipitation on the reservoir
surface, and two-thirds reclaimed water exported from the South Tahoe Public Utility
District's plant.
2. Because the drainage area above the reservoir is small (1700 acres) it may
be expected that as the volume of exported water increases, the quality of impounded
water will increasingly be influenced by the reclaimed water.
3. Estimates of runoff and evaporation rates previously reported to the STPUD
by its engineering consultants appear to be sufficiently valid to permit reasonable
water budget estimates for Indian Creek Reservoir.
k. Infiltration rates in the reservoir in mid-1969 were estimated to average
about 0.035 ft of water per day; a reasonable value for the type of soil in the area.
During 1970-71 the estimated rate was 0.028 ft of water per day. The decrease is
reasonable considering the expected clogging of soil pores as the reservoir matures.
5. The clarity of Indian Creek Reservoir water during the period of observation
was typical of shallow impoundments of relatively good quality water. During the
period June 1969 through April 1971 Secchi disk readings varied from 0.8 to 6.5
meters.
6. Water temperatures in the upper stratum of the reservoir, where light and
other environmental factors are most favorable to plankton growth, reach an l8°-22°C
range also favorable to biological activity. In winter they fall below the lower
limit for biological activity.
7. With only minor exceptions, the observed data on physical characteristics of
the reservoir are in line with typical and explainable phenomena, although not in
sufficient detail to permit statistical evaluations.
8. Chemical analyses of impounded water show that there was little difference
in conservative chemical quality from top to bottom, indicating that the reservoir
water was generally well mixed.
9- Throughout the period of study the pH of the impounded water varied from 7.7
to 8.5, as compared to J.k to 8.8 in the influent reclaimed water. The average pH
of the impounded water remained close to 8.0, indicating that Indian Creek Reservoir
was in a healthy condition limnologically.
10. There is evidence that iron in the influent water is utilized in the bio-
logical cycle of the reservoir, although there was no evidence that it is a limiting
element.
11. In terms of conductivity and chemical components the water impounded at
Indian Creek Reservoir is of good quality for irrigation water.
12. Differences in concentration of conservative quality factors such as
chlorides in influent reclaimed and impounded water in the reservoir was clearly
the result of dilution and evaporation.
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13. Substantial evidence was found that bicarbonate alkalinity vas used as a
source of carbon by the biota of the reservoir during the period of study.
1*4-. There is a tendency for the COD of Indian Creek Reservoir water to be higher
in the growing season when algae are present.
15. The excess of suspended solids in impounded water over that in influent
reclaimed water is most evident during the growing season.
16. Wind movement across the reservoir has an important effect on mixing of the
impounded water.
17. Prior to September 1969 the impounded water was poorly mixed. Thereafter
dissolved oxygen indicated that mixing was occurring due to natural causes. The
installation of a mechanical aerator in June 1970 resulted generally in a good
vertical oxygen profile, although it did not completely forestall a repetition of
the oxygen depression which appeared each July.
18. Correlation coefficients for suspended solids versus the reciprocal of
clarity were found by the computer to be 0.88. When more than 50 percent of the
suspended solids were volatile solids, the correlation coefficient increased to
0-95-
19. Phosphorus was considered the limiting nutrient in Indian Creek Reservoir.
Average N/P ratios in the influent reclaimed water were of the order of 150:1.
In the impounded water the ratio averaged 1^0:1 during 1969-70 but increased to
300:1 in 1970-71; probably as a result of increased efficiency of phosphorus
removal in the STPUD plant.
20. With but little effect of dilution the ammonia concentration changed from
more than 15 mg/,0 in the influent water to generally less than **• mg/j} in the
impounded water. Nitrogen balance and microbiological studies showed that nitrogen
is being lost from the reservoir and that nitrification-denitrification is the
major mechanism.
21. Two estimates made from different independent approaches place the total
nitrogen lost from the reservoir during two years in the range of from 6l,000 to
8^,000 kg; more than 60 percent of the influent nitrogen.
22. Apparently there is a slight tendency for nitrate and ammonia concentrations
to increase with time. Should this prove to be real rather than apparent the
reservoir would eventually become untenable to trout.
23. Biologically, Indian Creek Reservoir showed important changes over a two-
year period of observation. From an initial situation in 1969 in which it
apprently would not support fish life, it developed in 197° into an excellent trout
fishery.
2k, Evidence that with time the reservoir increased rather than decreased in
biological health was found in an increase in the diversity of benthic invertebrates
from 1969-70 to 1970-71. In October 1969 dipterous larvae averaged 428 per square
foot, whereas in October 1970 the value was only 280 per square foot. Nevertheless
the low oxygen tolerant types which predominated in 1969 were far less evident in
1970.
25. Although the diversity of benthic organisms is lower than might be expected
in a mature reservoir it is continuing to increase as the reservoir continues to
stabilize. However, the benthic standing crop is decreasing with time, hence the
amount of food available from the benthos to the fish population may be decreasing.
26. Changes in the contents of the stomachs of trout from 1969 to 1971 indicate
that some changes took place in the llmnological condition of the reservoir.
Chironomids predominated in 1970; Daphnia in the spring of 1971; and snails in the
summer of 1971-
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27. Apparently several annual cycles have teen established in Indian Creek
Reservoir. An annual spring phytoplankton bloom appears to start in February.
This is followed by an April-May bloom of Daphnia. It is concluded, however, that
additional seasonal data are necessary before it can be said with certainty that the
reservoir has stabilized.
28. Plankton surveys made in 1969, 1970, and 1971 indicate good biological
productivity of Indian Greek Reservoir water.
29. Vascular plants in Indian Creek Reservoir affected the dissolved oxygen
resource of the impounded water to a marked degree, although their importance to
the nutrient balance was minimal.
30. Five or six varieties of vascular plants are increasingly profuse in the
reservoir during the summer and could conceivably become a nuisance in future years.
31. Bioassays of impounded water showed limited growth rates of test algae,
probably because of a prior tieup of nutrients, particularly of phosphorus, in the
standing crop of aquatic organisms in the impounded water.
32. Growth rates in bioassays of impounded water were inversely related to the
biological growth cycle of the reservoir.
33- Water impounded in Indian Creek Reservoir, although supporting biota, was
nevertheless more capable of stimulating growth in bioassays than was the influent
reclaimed water.
3^. Unquestionably the factors controlling the behavior of Indian Creek Reservoir
are far more complex than can be predicted by merely analyzing its major influent
waters.
35- Observation of Indian Creek Reservoir over a period of time may make it
possible to design water reclamation processes capable of producing a water of
balanced quality suited to a broad spectrum of recreational or other uses.
36. The STPUD water reclamation plant is a highly efficient system for removing
phosphorus, and Indian Creek Reservoir is a good system for removing nitrogen.
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SECTION II
RECOMMENDATIONS
It has been shown in the work herein reported that Indian Creek Reservoir has changed
in quality characteristics from an initial condition in which it closely resembled
the influent reclaimed water from the STPUD, to a system clearly more complex and
capable of supporting biota which at first could not live in it. Should this trend
continue it may be that in time the reservoir will become excessively eutrophic
regardless of the quality of exported water, just as lakes have done under normal
inputs from precipitation and runoff. Should this occur, much of the purpose of
tertiary treatment of waste water becomes questionable. To clarify this question
it is recommended that a program of monitoring of the Indian Creek Reservoir be
continued and the data analyzed annually.
Less comprehensive objectives of the recommended monitoring program include: l)
determining whether the ability of Indian Creek Reservoir to support aquatic life
is increasing or decreasing, and 2) observing whether the suspected slow increase
in nitrate and ammonia is in fact occurring. This will give information as to the
importance of nitrogen removal as a treatment process.
It is recommended that studies beyond the scope of the Indian Creek Reservoir study
herein reported, but suggested by its findings, be conducted for the purpose of
determining: 1) the feasibility of utilizing intermediate size ponds to reduce the
nitrogen content of a phosphate-stripped water, and 2) the optimum nutrient levels
and relationships for impoundments to be used for recreational or other specific
benefits, with the intent of establishing more rational parameters of treatment
plant design.
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SECTION III
INTRODUCTION
ORIGIN OF INDIAN CREEK RESERVOIR
Indian Creek Reservoir is the terminus of a system designed to export from the Lake
Tahoe Basin the final effluent from the domestic waste water treatment facilities
of the South Tahoe Public Utility District (STPUD). The concept that sewage should
he removed from the Tahoe Basin developed during the early nineteen sixties. At
that time it was "becoming widely apparent throughout the U.S.A. that the growing
population pressure on the nation's water resources was leading to overfertilization
of surface waters, with consequent algal "blooms that interfered with normal "bene-
ficial use of such resources. In many instances losses were identifiable in
economic terms as well as in depreciated aesthetic and recreational values.
In the specific case of Lake Tahoe, discharge of waste water effluents directly
into the lake had never "been considered an acceptable alternative. However, prior
to about the year 1960 disposal on land within the basin was generally considered
adequate to overcome the public health and aesthetic objections to discharge into
surface waters of the region. Nevertheless, it was recognized by water quality
control authorities and others that the clarity and beauty of Lake Tahoe was a
consequence of an extremely low productivity resulting from its oligotrophic (nutrient
poor) characteristics. Moreover, it was evident that the Lake Tahoe Basin is essen-
tially a closed system subject to human imports of nutrients "but to only limited
export of nutrients, principally via the Truckee River and some selective logging.
Thus the lake is the ultimate nutrient sink in the basin. In such a situation in
1960, sewage disposal was considered the most critical unsolved problem.
Under a grant from the Max C. Fleischmann Foundation of Reno, Nevada, the Lake Tahoe
Area Council conducted a comprehensive study on protection of the water resources
in the Lake Tahoe Basin through management of wastes. The resulting report [1]
recommended export as one of the three feasible alternatives. At about the same time
(1961) the STPUD retained consulting engineers to develop a long-range permanent
solution to its disposal problems.
The idea of export as a practical solution to the waste management problem of the
Lake Tahoe Basin, however, developed slowly. No community was willing to be the
terminus of any waste export scheme. The concept that water is forever "sewage"
once it has "been used to transport wastes proved to be too deeply ingrained in the
minds of citizens to "be overcome "by simple persuasion. "If it is not good enough
for you, it is not good enough for me" was the ultimate attitude. This rationale
precluded both export "by way of the Truckee River and by pipeline as well, although
the latter offered more possible alternatives.
Matters were finally "brought to a head as a result of a growing national concern
over eutrophication. This initiated a review of water quality criteria that has
increasingly led in the direction of nutrient removal as an obligatory objective
of waste water treatment. A series of demonstration grants to the STPUD were made
under the Advanced Waste Water Treatment program of the series of federal agencies
which culminated in the Environmental Protection Agency. These grants led to the
development on a plant scale of processes for nutrient removal and for upgrading
waste water in quality to drinking water standards. Thereafter to make export
feasible it was only necessary for people to understand that what constitutes
acceptable high quality water almost anywhere is not adequate to protect Lake Tahoe
from eutrophication because of the lake's sensitivity to nitrogen at levels far
below those acceptable for drinking water.
The Indian Creek Reservoir site was selected as a logical place to impound reclaimed
water because it offered an agricultural use of water without release to surface
streams.
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CHARACTERISTICS OF INDIAN CREEK RESERVOIR
Indian Creek Reservoir is located in Alpine County, California on the eastern side
of the Sierra Nevadas on a tributary of Indian Creek in Diamond Valley. Figure 1
shows its general relationship to Lake Tahoe, Luther Pass, and other geographical
features of the area, as well as the profile of the 27-mile reclaimed water export
line from South Lake Tahoe.
The reservoir was formed in 1968 "by the construction of a rockfill dam, 68 feet in
height, across the tributary to Indian Creek, together with a smaller saddle dam
of the same type to prevent overflow of the reservoir into a shallow and little used
impoundment known as Stevens Lake. In preparing the reservoir site the original
vegetation, comprising mostly scrub brush and pinon pine, was removed and the
existing shallow soil stripped down to a stratum of quite impervious hardpan and
rock which characterizes the area. In this manner it was intended to minimize the
organic matter initially present on the bottom of the reservoir which might subse-
quently become a nutrient for organic growth in the overlying water.
The spillway crest of the main dam was established at an elevation of 5600 feet
above mean sea level. Thus it is about 625 feet below the water surface elevation
of Lake Tahoe and some 2100 feet below the summit of Luther Pass. At maximum water
surface elevation (5^00 feet) the surface area of the reservoir is approximately
l6o acres, or about 9 percent of the 1700 acres of drainage area above the dam.
The maximum volume of impounded water is about 3130 acre feet.
Although the reclaimed water from the STPUD is essentially of drinking water quality,
its disposal to the Carson River system is not permitted under standards established
to preserve the exceptionally low dissolved solids content of the West Carson River.
Therefore the reservoir is operated without overflow by releasing to irrigated
agriculture during the growing season the water impounded during the previous winter.
This results in a maximum variation in water surface elevation between 5600 and 5582
feet and a volume variation between 3130 and 1000 acre feet. Such an extreme
variation, however, is not expected to occur until after the year 2000, at which
time the anticipated export from South Lake Tahoe will approach the 1^,000 acre feet
of water that agriculture in the Immediate area can probably accept at its full
potential. Thus it is evident that the operational schedule of Indian Creek Reservoir
will have some seasonal effects on the quality of the impounded water.
Other factors governing the quality of stored water, beyond the degree of treatment
of the water exported by the STPUD, include the climatological and hydrological
characteristics of the reservoir area. As shown in Figure 2 (Section IV) the long
axis of the reservoir lies along the meridian. Thus it parallels roughly the
adjacent Sierra Nevadas to the west. The mountain range in turn protects the
reservoir from the prevailing winds but guides local winds along the axis of the
reservoir on a generally south to north path. Cover on the drainage area varies
from pinon pine on the east to a stand of timber intermingled with scrub brush on
the west. This cover varies in density from quite heavy brush to isolated stands
of timber. Slopes are steepest on the westj on the order of 10 to 20 percent at
lakeside. To the east the slopes are more moderate, averaging about one-half the
values cited.
The climate of the Indian Creek area is typical of that of the eastern or "rain
shadow" side of the Sierras at altitudes in the 5000 to 6000 foot range. Average
annual precipitation at the reservoir is reported [2] to be about 20 inches, with
70 percent of this total occurring during the winter, November through April, season
of the year. Although snowfall is substantial during the winter, rainfall accounts
for much of the precipitation. Average monthly records from the U. S. Weather
Bureau gage at Woodfords, California, some 3 miles northwest of Indian Creek
Reservoir, show a variation from 0.3^- inches in the months of July and August, to
U.28 inches in January, when prevailing storms occur. In spite of the small amount
of summer rainfall it is likely to be intense. Rapid rise of heated air up the
face of the mountains occasions thunderstorms and, because the soil in the Indian
Creek area is shallow and on appreciable slopes, some of the summer precipitation
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I
8,000
7,000
6,000
5,000
Treatment
-Plant
Pumping Station
Indian Creek
Reservoir
J
10 15 20
DISTANCE, mile*
25
30
FIGURE I. GEOGRAPHICAL RELATIONSHIPS, INDIAN CREEK
RESERVOIR AND EXPORT LINE FROM LAKE TAHOE
BASIN (2,3)
9
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can be expected to run off into the reservoir. At times of more seasonal rainfall
or of snowmelt on frozen ground, however, considerably more input of meteorological
water is to be expected. In contrast with natural runoff, inputs to the reservoir
through the export pipeline of the STPUD are continuous the year round, being
greatest during the summer season when the transient population of the Lake Tahoe
Basin is greatest. Thus the effect of surface runoff on the nature of water reaching
the reservoir is less in summer than would normally result from climatological
variation in the Indian Creek area. An estimate of the nature of this variation
reported in 1970 [k] is as follows:
1. Maximum monthly runoff of surface water to reservoir, approximately 4-9 times
the minimum.
2. Maximum input of reclaimed water: approximately 6.4 times the minimum.
3. Minimum ratio of reclaimed water to surface runoff: 1/2.66 (January).
4. Maximum ratio of reclaimed water to surface runoff: 118/1 (July, August,
September).
5. Anticipated composition of impounded water on annual basis:
Meteorological water 30 percent
Reclaimed water 70 percent
Evaporation from the surface of Indian Creek Reservoir is a factor in water quality.
Rates of evaporation in the area are greatest during the period, May to October.
At this time the daytime temperatures are highest, leading to a convective rise of
air mass up the face of the adjacent Sierra Nevadas which rise to elevations of
from 7800 to more than 9000 feet. Nighttime cooling of the air mass at higher eleva-
tions due to back-radiation through the relatively thin atmospheric cover contributes
to a subsidence of cool air at night, resulting in a day to night temperature change
which may range from 25 to 40 degrees. Thus although the reservoir is sheltered
from prevailing winds, there is a considerable movement of air which scavenges the
water surface of its overlying blanket of moist air and so encourages evaporation.
Evaporation losses during the four warmest months may average some 24 inches, 7
inches of which occurs in July. During the period of study herein reported the
annual evaporative loss from Indian Creek Reservoir is estimated at 40 inches.
Because of the relatively small percentage of surface water in comparison with re-
claimed water and the operating schedule which calls for withdrawing by discharge to
irrigation and by evaporative and percolative losses the entire reservoir input each
year, it may be expected that the water impounded in Indian Creek Reservoir will
resemble reclaimed water more closely as time goes on.
NEED FOR STUDY
Need for the study herein reported has both utilitarian and practical scientific
aspects. In as much as the process of tertiary treatment of waste water is far
from its ultimate technological and economic optimum, the creation and utilization
of Indian Creek Reservoir raised a number of important questions, including:
1. How effective is tertiary treatment at present levels of development in
controlling algal growth in impoundments of effluents from such treatment?
2. What limnological developments in impounded tertiary effluents will affect
beneficial uses of such impoundments?
3. What degree of treatment would be necessary to permit retention of reclaimed
water in the Lake Tahoe Basin without posing a threat to the quality of Lake Tahoe
water?
4. Given recreational or other beneficial uses as objectives of water reclamation,
what treatment processes are required to produce water of optimum quality
characteristics?
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Answers to the first two of these questions are badly needed in order to evaluate
the processes currently classed as "advanced" or "tertiary" treatment in relation
to their objectives.
The third question should be answered because it may not be assumed that tradeoffs
between exports from Lake Tahoe via the Truckee River and via pipelines will not
some day have to be adjudicated; nor that present social, cultural, and aesthetic
attitudes toward reclaimed water will endure forever. Conceivably, water of a
quality equal to that of Lake Tahoe may eventually be produced routinely from waste
water and be in demand by people living in the Basin at that point in time.
The fourth question is of particular importance in the economic management of the
environment. In contrast with the current practice of adding new unit processes to
waste treatment as rapidly as they are developed in the belief that the more the
treatment the less the pollution, this question envisions the possibility that an
optimum balance of water quality factors might be established for the specific
beneficial uses desired and waste water treatment processes tailored to produce that
desired product.
Interwoven in the need to answer questions such as the foregoing is the need, and
the opportunity, to trace the biological and ecological history of an impoundment
of highly treated waste water created on previously vegetated dry land. The manner
in which such an impoundment matures with time is all important to answering the
four questions cited. Moreover, it affords an opportunity never before presented to
collect scientific data of exceptional pertinence to the problem of control of
eutrophication of surface waters.
OBJECTIVES OF STUDY
The general objective of the study was to collect and evaluate data needed in
answering questions such as outlined in the Weed For Study. Specific objectives
included:
1. To relate the biological, physical, and chemical characteristics of Indian
Creek Reservoir to the corresponding characteristics of reclaimed water from the
STPUD Wastewater Reclamation Plant.
2. To trace the seasonal and temporal changes in the biological, physical, and
chemical characteristics of Indian Creek Reservoir.
3. To relate the observed characteristics of the reservoir water to the nutrient
concentrations and biostimulatory characteristics of the influent reclaimed water.
^. To evaluate the relative contribution of biostimulants contributed by the
reclaimed water and by exchange from the underlying soil and sediments.
NATURE AND SCOPE OF REPORT
The report herein presented covers work done on the Indian Creek Reservoir pursuant
to the objectives of the study during the period December 1, 1968 through May Jl,
1971 under a combination of Demonstration Grants No. 16010 DSW and 16010 DNY. In
as much as the former of these two grants included objectives other than those
related to Indian Creek Reservoir, many of its findings are published separately [5].
The report draws also upon findings of other cooperating agencies (see Section VII
Acknowledgments) which are either published elsewhere or included herein in the
Appendix (Section XI).
Because the work was conducted over two consecutive grant periods which ended on
May 31 of each year, the data were analyzed and evaluated at the end of each of two
study periods (April 1969 through March 1970, and April 1970 through May 1971). In
preparing the report the results of these two study periods were compared
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reason that filling of the reservoir and acclimating of the newly inundated land
occurred during the,first year, whereas normal operating plans were in effect during
the second. Thus the results obtained during 1969-70 might reveal Important limno-
logical factors in the development of the reservoir which might become either more
or less critical in the more established impoundment of 1970-71- Such a consideration
is especially important wherever averages are used in the report to describe the
physical, chemical, or biological responses of the reservoir.
The report draws upon and extends figures and tables previously published in a First
Progress Report [k]. It is therefore intended to stand as a final report, although
its findings may later be combined with subsequent data if the project continues
through future years.
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SECTION IV
PROJECT DESIGN AND METHODOLOGY
PROJECT DESIGN
The project was designed around a program of sampling, analysis, and evaluation and
interpretation in terms of the objectives of the study. The scope and details of
the sampling and analytical aspects were designed to determine, within budgetary
and climatological limitations, l) the amount of nutrients entering the reservoir;
2) the effect of such nutrients on the level of productivity of the reservoir; and
3) the environmental fate of these nutrients. It was particularly desired to learn
whether nutrients are sequestered in the reservoir sediments or biota, escape to
the surrounding environment via the atmosphere, or pass through the reservoir with
outflowing water.
Sampling stations were chosen at the locations indicated in Figure 2. Initially,
the reclaimed water influent to the reservoir (herein designated by the symbol, III)
was sampled at the inlet to the pressure outfall line at the STPUD plant, some 27
miles from Indian Creek Reservoir. Beginning in July 1969, however, this influent
sampling was made at the Luther Pass pumping station (see Figure 1, Section III),
some 10 miles closer to the reservoir. Discharge from the reservoir (herein desig-
nated by the symbol, B) was sampled and measured in rate at a valved outlet pipe in
the main dam from which water is discharged in significant amounts during the irriga-
tion season. At other times continuous leakage occurs at a rate of about 15 gallons
per minute due to poor seating of the valve. By June 1970 it was evident from
analytical results that the chemical quality of the discharge (B) was no different
than that of the reservoir water because of the high degree of mixing of the
impounded water. Therefore sampling of the discharge was discontinued. A composite
sample of the impounded water (herein designated by the symbol, C) was made up of
several portions collected around Station 1 (Figure 2). Comparison of analyses of
samples from this and other stations in the reservoir showed that Station 1 yielded
a good estimate of the levels of nutrients and other constituents of the Impounded
reservoir water.
SAMPLING PROGRAM AND METHODS
Beginning in April 1969 the influent (ill) and composite sample (C) of the reservoir
were collected in one-gallon lots as often as weather conditions permitted, but
generally on approximately a weekly schedule. Normally, reservoir sampling was
made by use of a trailer-mounted 12-foot aluminum outboard motor boat. Of necessity
this equipment had to be stored at the Lake Tahoe Area Council Laboratory some 60
miles from the reservoir, hence when road conditions made transfer of the boat
difficult, a one-man inflatable rubber boat was used to collect reservoir samples.
During the 1969-70 season vertical sampling at Stations 1, 2, and 3 (Figure 2) were
made over a 24-hour period at different seasons of the year in order to define
variations in the horizontal and vertical distribution of various quality constituents
of the impounded water. During these 24-hour sampling studies personnel camped over-
night at the reservoir, using a gasoline-powered generator to provide electrical
power for lighting and for operating analytical equipment such as pH meters and
magnetic stirrers. When it was established that the reservoir was well mixed, the
24-hour schedule was discontinued as a routine procedure. Thereafter (1970-71)
sampling in depth was made in a vertical section at Station 3 only, on each sampling
date.
Bottom sediments, benthic invertebrates, phyto- and zooplankton were sampled at
intervals to study the aquatic community of Indian Creek Reservoir. A composite
sample of the soil from 20 stations around the impoundment was collected in the
-------
(Collected at STPUD
or Luther Pass
Pumping Station)
Saddle Dam
STPUD
Pipeline
Indian Creek
Reservoir
Spillway
Snow
Sample
Runoff
FIGURE 2. LOCATION OF SAMPLING STATIONS AT INDIAN
CREEK RESERVOIR
-------
zone a"bove the water line from which vegetation had "been stripped in preparing the
site in order to get some idea of the provable organic content of the reservoir
bottom initially.
Temperatures were measured using a laboratory thermometer (-10° to 110°C). Light
readings were taken with a Gossen Tri-Lux C light meter with a 20x translucent
filter. The Secchi depth was determined as the average point of disappearance for
an ascending and descending-8 inch diameter white, flat, circular, metal plate.
Reservoir depth was read from a staff gage installed at the main dam.
The influent, discharge, and reservoir composite water samples were collected
directly in polyethylene bottles used as sample containers. Samples at different
depths below the water surface were collected with either an all plastic-latex
rubber, Van Doren water sampler or a plastic Kemmerer sampler and transferred to
polyethylene bottles. Bottom sediments were sampled by means of an Ekman dredge.
Although rocks and sticks interfered with operation of the dredge in some shoreline
areas, it was generally not too difficult to collect adequate lake sediment (as
opposed to the soil stratum constituting the reservoir bottom). Usually a depth of
1-2 inches of silty-clay was collected at each sampling site. This was screened
(U. S. No. 30) when collection and analysis of benthic invertebrates was the objec-
tive, or mixed and placed in a sample container for later chemical analysis. Phyto-
plankton samples were collected as water samples. Zooplankton were counted directly
in water samples or collected by either surface tows or vertical tows (bottom of
reservoir to surface) using a Wisconsin Style Plankton net (No. 20 mesh nylon) and
bucket.
Records of climate and of the flora and fauna observed in the Indian Creek Reservoir
basin were also collected during the sampling trips to Indian Creek Reservoir. For
example, wind direction and speed, cloud cover, and unusual climatological conditions
were recorded regularly in a permanent log book. Also, visitations to the lake of
deer and migratory waterfowl (principally, ducks and grebes) were observed and
recorded. The location of developing vascular plant communities, floating algal
material, ,and similar phenomena which would be expected to indicate changes in the
reservoir conditions were noted. Data on the developing fish population were
obtained, principally from the Department of Fish and Game.
In addition to the regular program of sampling of influent and impounded waters,
samples of surface runoff were collected when such runoff was observed.. However,
because of the dry environment, very little runoff occurred during the summer months.
As a rule summer precipitation takes place during a relatively short period of time
and is rapidly absorbed or drained into the reservoir. This decreased the likelihood
of personnel being on the site to obtain samples when runoff occurred.
Data obtained from studies conducted by the Environmental Protection Agency, the
California Department of Water Resources and of Fish and Game, and the South Tahoe
Public Utility District were also used to supplement direct observations made by
the project staff.
TREATMENT OF SAMPLES
Methods of field and laboratory treatment, as well as storage, of sample were
designed to maintain continuity of the work load in the laboratory without sacri-
ficing accuracy of the results of analyses for such characteristics as: DO, COD,
BOD, SS, VSS, nitrogen series, orthophosphate, total phosphorus, iron, chlorides,
calcium, alkalinity, pH, conductivity, and the biostimulatory properties of various
concentrations of the sample.
Water samples-were normally transported to the laboratory and stored overnight in a
refrigerator (< 5°C) for chemical analysis the following day. When it was not
possible to begin analysis on such a schedule, the water samples were filtered and
the filtrate frozen for analysis at a later time. Analysis for DO and BOD were
begun in the field (reagents added up to and including the concentrated
-------
Initially pH and. alkalinity were determined in the field; however, no differences
due to the time involved in transporting samples to the laboratory were observed
and so all other analyses of the regular weekly water samples were performed in
the laboratory. However, with the overnight sampling studies of the vertical and
horizontal variations of chemical components during a 2k-hour period, measurement
of DO, temperature, pH, and alkalinity were made as soon as possible after collection.
Samples were then composited for the different depths and stations and returned to
the laboratory for further chemical analysis.
Phytoplankton were placed in brown glass jars and preserved in the field in a 5
percent NaaCOa neutralized formalin solution. Zooplankton were preserved in 5-10
percent neutralized formalin in brown glass jars. The benthic invertebrates were
placed in glass jars after having been screened and rinsed with reservoir water and
15 percent neutralized formalin was added for preservation. Bottom sediment samples
were placed in brown glass jars and brought back to the laboratory for later analysis.
ANALYTICAL PROCEDURES
Preparation of Samples
Preliminary preparation of samples for physical and chemical analyses and bioassays
varied somewhat depending on the specific method chosen for each assay. Water
samples selected for flask bioassays, including Lake Tahoe water used for dilution,
were filtered through Whatman glass fiber filters (GF/C) and finally through
MilliporeW filters (HA, 0.^5 n pore size). They were then stored in tightly stop-
pered polyethylene containers and frozen, unless the test was to begin within five
days. For chemical analyses aliquots of the samples, both the unfiltered and those
passed through the previously described glass fiber and MilliporeW filters, were
kept in tightly capped 2-& polyethylene containers and stored in a refrigerator at
temperatures approaching 0°C until all chemical determinations were completed. It
was determined that no significant difference existed between chemical analyses of
nutrients measured in unfiltered or filtered samples.
Chemical Assays
Chemical analyses of the filtered and unfiltered water samples were made according
to Standard Methods [6] in determining biochemical oxygen demand (BOD), chemical
oxygen demand (COD), pH, alkalinity, organic nitrogen, ammonia, chlorides, total
phosphorus, calcium, and conductivity. Methods described by Strickland and Parsons
[7] were considered more suitable for iron, nitrite, nitrate, and reactive inorganic
phosphorus at the low concentrations prevailing in the Tahoe samples. Details of
individual analyses are presented in Appendix G [k]. All laboratory chemical determ-
inations were subjected to replicate analyses on aliq_uots of the same sample [8,9] to
determine the precision of results attainable by the project staff by the analytical
procedure used. The results showed that with the exception of organic nitrogen and
total phosphorus in Lake Tahoe water, where concentrations are extremely small, the
chemical analytical work is of good precision in terms of the coefficient of varia-
tion. A statistical analysis of the two methods of laboratory filtration (0.45 n
HA Millipore and GF/C Whatman glass fiber filter paper) indicated that there is no
essential difference in the accuracy of the two methods.
Sediment chemical composition on a dry weight basis (available P, organic carbon,
total N, and particle size) was determined according to methods described by
Porcella, Kumagai, and Middlebrooks [10].
The technique for measuring total suspended solids (SS) and volatile suspended solids
(VSS) was patterned from a combination of the procedures outlined in Standard Methods
[6]; Strickland and Parsons [7]; and Maciolek [11]. Whatman glass fiber filters
(GF/C) were used in solids preparation. The filters were prepared by soaking in
distilled water to wash the fibers free of salts. They were then placed in a 103°C
hot air oven overnight. Thereafter they were placed in a muffle furnace for
16
-------
30 minutes at U50°C to destroy any organic matter present without fusing the glass
fibers. After cooling, the filters were dried in a hot air oven at 103°C and tared
quickly on a Mettler semimicro balance, to avoid error due to the hydroscopic nature
of the dried filter. In making the solids determinations the sample was applied to
the filter until the volume of sample had passed through, or until the filter was
completely clogged. The volume of filtrate was then recorded. The filters with
their load of suspended solids were dried overnight at 103 °C and the dry weight
recorded to the nearest 0.01 mg. To determine the VSS present in suspended solids
the loaded filters were then redried and reweighed to verify the SS value. They
were then ignited at k^O°C for 2 hours, soaked with a few drops of distilled water
to rehydrate the mineral matter, dried overnight at 103°C and weighed. The loss in
weight was recorded as VSS in mg/,0.
In some cases it was necessary to revise the suggested methods in order to expand
the scope of the analysis to encompass the wide range of nutrient concentrations
encountered in the various samples assayed. The procedure was to prepare two
standard curves for the Sectarian Model B spectrophotometer, one using a 1-cm pathway
cuvette and the other a 5-cm cuvette. The range of concentration for N, P, and Fe
using the two pathway cells was from 1 pg/^ to 200 |og/£. Samples in which the level
of the constituent exceeded the maximum range of concentration were diluted to the
concentration range of the cells by a calibrated volume of deionized water.
Flask Bioassays
Samples of STPUD effluent (ill), impounded water (C), and reservoir discharge (B),
as well as some selected shoreline samples, were assayed by the flask bioassay
technique [8,9] both undiluted and diluted to 10$ and 1$ concentrations in Lake
Tahoe water.
In making the assay the filtered sample was first diluted to the desired concentration
with filtered Lake Tahoe water. One hundred and fifty m& of this solution was then
placed in each of five sterile 250 m& Erlenmeyer flasks. Glassware used in assays
was dry heat sterilized. Cells of a species of Selenastrum in good physiological
condition were centrifuged and washed twice in Lake Tahoe water to minimize the
chance of nutrient carry over from the stock culture to the test flasks. An equal
volume of the suspended cells was then added to each test flask, so that the concen-
trations of cells in the 150 m£ of liquid was approximately 50 cells/mm3.
Loose fitting plastic beakers were inverted over the tops of the inoculated test
flasks, prior to being placed in a 20°C constant temperature room and incubated on
a gently moving (30 cycles/min) shaker table for a period of five days. Illumination
of approximately 550 ft-c (5920 lux) intensity was provided by four kO watt G. E.
fluorescent lamps, No. F^O-CW, Coolwhite, four ft in length.
The cell concentration in the test flasks were determined by cell counts at the end
of 1, 3, and 5 days during the five week period of incubation. After the final counts
were completed, suspended solids and pH measurements were made on a composite of the
liquid in the five replicate flasks.
Test Organism
The alga Selenastrum gracile (Reinsch) was originally selected and utilized as a test
organism for assays on the basis of consideration of characteristics of an ideal test
organism and of favorable results reported by Skulberg [12] with the same genus.
It has the disadvantage of producing large cells under rich nutrient conditions.
In addition, newly formed cells tend to remain attached; but because they rarely
exceed four in a group, cells are easily distinguished by "hand" counting with a
microscope, These limitations were considered minor for the conditions prevailing
at Tahoe when the hand procedure was used. However, in July 1969 a Model B "Coulter"
counter was purchased to improve the efficiency and accuracy of cell counting. The
Coulter counter functions on the principle that as each particle passes through an
17
-------
orifice, it displaces its own volume of diluent within the orifice and thus momen-
tarily changes the resistance value between the electrodes positioned on each side
of the orifice. A cell count is recorded each time the resistance is changed. Thus,
the attached newly formed S._ gracile cells would be counted as a single cell instead
of the multiple number they represent. For this reason the closely related organism
Selena strum capricornutum which has the same approximate advantages as S_._ gracile,
but do not remain attached after division, was substituted in studies in which the
Coulter counter was used.
The basic culture of the two Selenastrum species were maintained at a constant growth
rate by the continuous culture^method (9 = 5 days) using a nutrient solution of 10
percent Skulberg's medium (Appendix B) [b], which is specifically designed for cultur-
ing Selenastrum. The purity of the Selenastrum species was checked periodically by
microscopic examination and contamination with other organisms was normally non-
existent. On one occasion this normal finding led to inadequate vigilance and a
contamination of the basic culture with a "Chlorella type" organism developed between
two successive microscopic checks. Consequently, the purity of the basic culture
used in the assays for a period of approximately six weeks in the fall of 19&9 i-s i-n
question. The results of the contaminated assays are discussed in later sections.
Counting Procedures
As noted in the previous section (Test Organism) two basic methods were used to count
the alga cells; the hand counting method up to July 1969 and the Coulter counter
method thereafter.
The hand counting procedure was initiated by removing a 10 m.0 aliquot from each flask
after an incubation time of one, three, and the final five days and centrifuging
the aliquot for 10-15 minutes at 2000 rpm (approximately 800 times gravity). After
centrifugation, 8-9 m.0 of the supernatant were removed with a Pasteur pipette and
the pellet of cells resuspended in the remaining liquid medium. A drop of the sus-
pension was then put on a Spencer Bright-Line hemocytometer for counting under the
microscope. Duplicate counts were made for each flask and five replicates were
performed for each concentration; thus a total of 30 counts were made for each concen-
tration of sample tested. The duplicate counts for each flask were averaged, and
the resulting values were then averaged to obtain a mean count for the five replicates
constituting the assay.
The method used in the Coulter counter technique involved removing a 10 m£ aliquot
from each flask. The aliquot was then diluted with a saline solution so that the
final concentration was from a maximum of 50 percent to the concentration that will
provide a final count of less than 100,000 particles (counting capacity of the
Coulter counter) for a 0.5 m£ diluted sample. The maximum time required for each
count is 13 sec. As was done in the hand count method a mean value was obtained for
the five replicates.
Reliability, Sensitivity, and
Precision of Cell Counting
Accurate cell counting techniques are imperative for meaningful kinetic studies of
algal growth. A comparison of the results of the conventional hand counting technique
versus the Coulter counter for the same samples was made. The results of the hand
counting technique varied somewhat with the magnification used, but mainly with the
ability of the individual doing the counting to judge representative cell concentration
areas, superimposed cells, attached cells, etc. The Coulter counter, however, when
in proper operating order, records each time a particle passes between the two
electrodes. A coincidence correction coefficient is multiplied by the number of
particles recorded by the Coulter counter, thereby, providing a statistical correction
for the possibility of superimposed cells passing between the electrodes at the same
time. Thus it is obvious that the Coulter counter should provide a much higher
degree of sensitivity and reliability as well as the added benefit of a considerable
18
-------
time saving over the hand counting technique. The reliability of the Coulter counter
was emphasized when the same sample was introduced to the Coulter counter several
times in succession and the difference in the numerical results were found to "be
insignficant (< 1 percent coefficient of variation).
Computer Analysis of Data
The computer was utilized to analyze the data more efficiently, especially to obtain
values of maximum growth rate, Q; log maximum growth rate, u.j mean maximum cell
concentration at the end of the growth period, ]£. The computer was also utilized
to determine the mean, coefficient of variation, range of 95 percent confidence
levels, and correlation factors. These determinations and their significance are
discussed in sections which follow.
-------
SECTION V
RESULTS OF STUDY
INTRODUCTION
Pursuant to the objectives and the program outlined in Section III, physical,
chemical, and "biological observations were made of the progressive changes in the
water "budget and in water quality in Indian Creek Reservoir (ICR). The results of
these observations are hereinafter presented and discussed; and further evaluated
in Section VI. The data presented and analyzed were collected by members of the
project staff; by the South Tahoe Public Utility District and the U. S. Weather
Bureau as a part of their normal operating procedures. Estimates by Clair A. Hill
and Associates for the STPUD [2] were also used in computing the water budget of
the reservoir.
PHYSICAL OBSERVATIONS
Water Budget of ICR
Filling of Indian Creek Reservoir was begun on March 51, 1968. Table 1 summarizes
the input of reclaimed water and withdrawals of stored water from the reservoir as
reported monthly by the STPUD during the subsequent three years (April 1968 through
April 1971), together with calculations which permit some preliminary conclusions
concerning the water budget of the reservoir.
Columns 1 through k of Table 1 represent data taken directly from the STPUD reports,
converted to ac-ft units. Column 5 represents the volume of water in ac-ft which
would have been in the reservoir at the end of each month were there no inflow from
surface runoff, or loss of water through evaporation to the atmosphere and infiltra-
tion into the soil underlying the reservoir. It may be noted that in some instances
these theoretical values exceed the actual 5150 ac-ft capacity of the reservoir.
Overflow, however, did not in fact occur because of actual losses and lack of over-
riding inputs by surface runoff. Column 6 reports estimates of the actual reservoir
volume based on depth gage readings and a cumulative capacity curve [2,4] in ac-ft.
From Table 1 it is noteworthy, though to be expected, that during the winter of
1968-69 the volume of water impounded in the reservoir increased rapidly in
comparison with the reclaimed water input. For example, by the end of April 1969
the actual volume of impounded water was 2280 ac-ft as compared with 1527 ac-ft
pumped to the reservoir from South Lake Tahoe. The difference, 955 ac-ft, therefore
represents the accumulation due to surface runoff after all infiltrative and
evaporative losses have been charged off. Subsequently, during the summer of 1969
the withdrawal of 522 ac-ft in August and September did not change the volume of
water impounded in the reservoir. Consequently this value may be taken as a rough
estimate of the net input to the reservoir during a two-month period from sources
other than reclaimed water. Similar estimates of the net inflow during 1970 and
1971 .may be derived from the data presented in Table 1.
Data from Table 1 for each of two 12-month periods are utilized in Table 2 in
developing a water budget for Indian Creek Reservoir. These data are designated
by the symbols I, D, and AS in the table. Other values for use in the water balance
equation, E + PQ = I + RO + PL - D - VQ - AS, were estimated as hereinafter outlined.
Definition of each symbol in the equation is noted in column 5 of Table 2.
21
-------
TABLE 1
SUMMARY OP RECLAIMED WATER INPUTS TO INDIAN CREEK RESERVOIR
(April 1968 - April 1971)
(STPUD Monthly Reports)
1
Year
and
Month
1968
Apr
May
Jun
Jul
Aug
Sep
Oct
Ndv
Dec
1969
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
1970
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
1971
Jan
Feb
Mar
Apr
2
Daily Flow to Indian Creek
Reservoir (mgd)
Maximum
2.4
2.4
3.1
3.5
2.7
3.6
1.8
2.2
2.5
4.1
2.5
3.8
3.3
3.0
3.8
2.8
3.0
2.6
2.0
2.0k
3.37
5.4o
3.16
3.01
2.32
3.0^
3.22
3.26
3.36
3.37
2.35
2.77
3.24
3.9
3.6
3.3
3.4
Minimum
0.9
1.9
0.0
1.8
1.9
0.0
1.1
0.2
0.8
1.1
l.U
1.6
2.2
1.0
2.0
2.2
1.9
1.8
1.5
1.07
1.28
1.74
2.10
1.87
1.06
1.89
2.05
2.32
2.70
1.96
1.77
1.62
1.52
1.2
1.5
2.1
2.5
Average
1.84
1.96
2.4
2.7
2.5
1.7
1.6
1.52
1.6
2.2
1.9
1.9
2.6
2.1
2.67
2.5
2.7
2.1
1.8
1.67
2.06
2.80
2.34
2.31
2.05
2.14
2.51
2.75
3.01
2.47
2.06
2.06
2.28
2.36
2.49
2.56
2.8
3
Total Inflow
For Month
(mgd)
55.1
60.77
66.9
82.8
76.7
51.6
48.0
37.9
49.8
69.0
53.9
57.5
76.8
63.9
8l.o
75.9
82.3
61.9
56.4
50.18
63.93
86.97
65.52
58.19
61.55
66.49
75.45
85.29
93.57
74.12
64.04
61.96
70.70
73.2
70.0
79.2
84.5
(ac-ft)
169
186
205
254
235
158
147
116
153
212
165
176
236
196
249
233
253
190
173
154
196
267
201
178
189
204
232
262
287
227
197
190
217
225
215
243
259
4
Widthdrawn
for
Irrigation
(ac-ft)
0
0
0
302
369
414
0
0
0
0
0
0
0
0
0
0
319
203
0
0
0
0
0
0
0
4
152
629
951
6i4
0
0
0
0
0
98
25
5
Cumulative
Total
( Input
Minus
Withdrawn)
(ac-ft)
169
355
560
512
378
122
269
385
538
750
915
1091
1327
1523
1772
2005
1939
1926
2099
2253
2449
2716
2917
3095
3284a
J484a
3564a
3197a
2533
2146
2343
2533
2750
2975
3190a
3335s
5569s
6
Total in
Indian
Creek
Reservoir
Observed
or
Computed
(ac-ft)
280
2280
2200
2300
2350
2150
2100
2150
2100
2300
3080
3100
3080
3000
2700
1940
1540
1520
1620
1820
2080
2260
2410
2600
aExceeds 3130 ac-ft, capacity of Reservoir.
22
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TABLE 2
WATER BUDGET, INDIAN CREEK RESERVOIR
1
Period
April
1969
through
March
1970
April
1970
through
March
1971
2
Symbol
E
P
o
I
RO
D
PL
V
o
AS
E
P
o
I
RO
D
PL
V
o
AS
3
Item
Evaporation from reservoir surface
Percolation through reservoir bottom
Influent reclaimed water from STPUD
Sub-basin drainage into reservoir
Water discharged from reservoir
Precipita directly on reservoir
Leakage through reservoir outlet valve
Change in volume of impounded water
during period shown in column 1
Evaporation from reservoir surface
Percolation through reservoir bottom
Influent reclaimed water from STPUD
Sub-basin drainage into reservoir
Water discharged from reservoir
Precipitation directly on reservoir
Leakage through reservoir outlet valve
Change in .volume of impounded water
during period shown in column 1
^
Quantity
(ac-ft)
387
2k26
2674
11^5
522
3^0
2k
+800
U50
1375
2687
815
2^8
225
2k
-570
^ i ^
Evaporation from the reservoir surface (E) was computed from the reservoir water
surface corresponding to the average gage height observed for each month of the
year, multiplied by the average evaporation rate for free water surfaces in the
Indian Creek area for the corresponding month, Depth-Area and Monthly Evaporation
Curves developed by Glair A. Hill and Associates [2,U] were used in this computation.
Precipitation on the ICR drainage area, and directly on the reservoir suface (Pr),
was taken from the U. S. Weather Bureau records at Woodfords which showed 28.02
inches for the 1969-70 12-month period. For the 1970-71 period the long-term
average value of 20 inches [2,^] was used.
Runoff (RO) was computed from monthly precipitation values (observed or average)
multiplied by monthly runoff factors estimated by Glair A. Hill and Associates
[2,4].
Leakage through the reservoir outlet (VQ) waa determined by measurements made by
the project staff, which showed about 15 gallons per minute as an average value.
Percolation losses through the reservoir bottom (PQ) were obtained by differences,
using the water balance equation. Thus the value for percolation reported in column
k of Table 2 represents actual percolative losses from the reservoir, plus or minus
the net error in assumption in evaluating other items in the water balance equation.
In exploring the inherent error resulting from the foregoing approach it was previ-
ously reported [k] that during the summer months of 1969-70 the apparent loss of
23
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water by percolation was around 0.035 feet of water per day. Such a value has been
shown [13] to be within the range which might be expected in tight soils continuously
inundated for more than a year. The apparent percolative losses for the full 1969-7°
and 1970-71 years of Table 2 are about 0.(A8 and 0.028 feet per day, respectively.
Neither of these values take into consideration the greater percolative capacity of
soils that are drained when the depth of water in the reservoir is decreased during
discharge — a refinement that is impossible to achieve with the available data.
Nevertheless, the values are reasonable and consistent with the well-known fact that
the rate of infiltration into a continuously inundated soil decreases with time.
Consequently they support the general conclusion that the water balance shown in
Table 2 is a reasonable estimate. From column k, however, it may be seen that the
estimated annual input to the reservoir from runoff and direct precipitation is of
the order of 2k to 3^ percent, as compared to the anticipated average annual value
of JO percent (Section III).
Physical and Environmental Parameters of ICR
Weekly observations of several physical parameters of Indian Creek Reservoir reported
in Table 13 (Appendix) are summarized in Table 3 for the period of study. Results
of similar 24-hour observations appear in Table 1^ (Appendix). Such detailed data as
clarity (Secchi), air and water temperature variations throughout the day and with
depth below the water surface are of particular importance in evaluating the quality
of water in the reservoir and its relationship to observed biological changes. In
the context of the physical characteristics of the reservoir, however, Table 3 is
adequate to reveal the magnitude and variation in water and air temperatures, and
in the clarity of the water as measured by the Secchi disk.
Clarity of Water. During the period May 1969 to May 1971 the clarity of the water
in Indian Creek Reservoir varied from 2.27 to 21.5 feet (0.8 to 6.5 meters). Figure
3 summarizes the Secchi disk data reported in Tables 3 and 13 (Appendix). It shows
that as the reservoir became more mature there was a marked tendency for the clarity
to increase. For example, during 1969 the maximum clarity occurred in December
when the Secchi disk reading exceeded 11 feet. However, in 1970 values in the 19 to
21-foot range appeared in April and July, and again in the October to December period.
In both years a period of high clarity appeared in the month of July, with minimum
values occurring in February and March. It is difficult to document the exact causes
of the winter decline in clarity. The greatest surface runoff occurred in December
1969^ This might be expected to bring in appreciable suspended solids from surface
wash. Considerable algal growth occurred in the February-March period in both years,
giving a green cast to the water and quite obviously reducing its clarity. However,
it might be said in general that the clarity of Indian Creek Reservoir was typical
of shallow impoundments of good quality water.
Temperature. From Table 3 it is evident that water temperature in the surface zone
followed ambient air temperature in a normal manner, with less response to transient
climatological phenomena. Of greatest significance to the water quality and bio-
logical productivity of the reservoir is the fact that the near-surface water
temperature maintained levels in the l8-22°C range over essentially a four-month
period each year. Figure k shows that the water temperature pattern for the 1969-70
year was essentially repeated in the 1970-71 period. Data presented in Table 13
(Appendix) show that some thermal stratification was evident from late May to
mid-July 1970 at which time the temperature drop from surface to bottom of the water
was of the order of 3 to 7.5°C. In September 1969 and again in September 1970 there
was no temperature difference between the surface and the 1^-meter level, indicating
good vertical mixing. That this was not simply the effect of the aeration turnover
system is evidenced by the thermal profile which existed in previous months under
similar aeration.
Environmental Factors. Although no daily observations are available at Indian Creek
reservoir, to identify the environmental factors of climate some general observations
are reported in column 8 of Table 3. Clear weather prevailed throughout the report
period. Wind direction seems to be heavily influenced by the adjacent mountain
-------
TABU }
VBKLX OBSBWATIOIO 07 miBOWDTTAL DATAj IXDUM CSDK raOBVOd
(mi 1969 - May 1971) .
1
Date
Max 1969
29
Jun
it
19
24
Jul
1
10
17
22
29
5
12
19
Sep.
2
10
15
25
Oct.
2
8
16
*
30
gov
13
19
26
Bee
3
16
Jen 1970
5
jeb
5
18
}
18
26
2
TU»
of
Day
(houra)
„
-
-
1140
1430
09»J
1030
0930
1030
1530
1545
1245
1245
1420
1400
1320
1050
1015
1150
1125
1125
1055
1100
1410
1515
1310
12U
1200
1145
3
Secchi
Depth
(autere)
1.68
1.17
0.91
2.18
2.05
1.47
2.22
1.81
3.12
2.68
1.50
1.75
2.69
1.95
1.22
1.40
1.12
-
1.27
1.88
2.18
2.80
2.80
>.o4
5.46
2.64
2.80
0.81
0.85
0.99
0.86
0.84
4
Water
Depth
(ft)
49-75
49.8
50.1
50.4
50.5
50.7
50.7
50.85
50.85
50.95
50.25
49.34
49.5
49.6
48.2
49.2
48.6
48.6
48.7
48.75
48.63
49.0
49.1
49.2
49.8
50.8
J-..1
54.6
54.75
55.5
55.2
5
Hater
Ttomp.
CO'
17
16
18
18
18
19
22
23.1
22.2
20.6
20.3
20
El
20.5
19
17
16
14
9.5
9
9
8.5
6.5
5
„
3
4
4.2
4
, 5 .
6.8
8.2
6
Air
Tfenp.
Co)
.
-
-
-
89.4
22.8
25.5
25
21.7
31
29.5
22.6
25
20.5
-
12
13.5
U..3
16
11
9
11
11
-0.5
10
5
8
4.8
12
7
Light
Intenalty
(ft-c)
-
-
-
6600
-
4900
5400
4600
5200
4600
4600
5&00
5500
5200
2200
4000 ''
1340
4400
4200
5000
4000
4000
4600
2800
2000
6400
6400
6400
5200
a
Remarke
-
-
-
Clear, aunahine. Blight westerly breeie, 2"-4" chop, water
•lightly turbid
Cloudy, thunderatora in dlatenca, aeptio odor detected
neer reaervolr outlet
Very clear, fev snail clouda, BOUtberly wind atrong et
timea
Clear aklaa, northerly vlnd
Sklea cryatal clear, vater eurface like glaaa
deer akiea, winds northveatarly
Cloudy, wind eonatant from aouthveat, vater aurfece choppy
Cleer, tev email clouda, vlnd calm to breese from veat,
vater aurfaoe gleaay to rippled
Strong veat vlnda 15-20 »ph, 20-50 japh at 1645 hr, vavee
Cleer, alight vlnde fron northveet, ripplea on veter
eurfece
Thin clouda, wind northerly, water near dan appeered
extremely dark
Storm clouda, northerly vlnda 30-40 mph, wevea 18"
amplitude
Patchy clouda, vinda aouthwaaterly atrong et tljwa, veter
rough but no whitecepe
Cuaulus cloud, overceat, alight breece fro* eouthwaat,
vater aurface cola
Clear, Bunny, no vevee
Clear and aunny, vater calm
Cleer akiee, thin clouda, alight northveat breete, water
aurfeoe ripplea
Clear aklee, light clouda
(Deo 15 no vlnd) Dec 16 eouthveet wind too strong for
aanpling all atatlona, wave aaiplltude 2-3 ft
Cleer blue aklee, elight eouthveet hreete, lake frozen
over except enall area to veat, Ice 5" at aampling atatlon
Cloudy, overcaat, wind ellght aouthveet
Sky blue to partly cloudy, clouda large dark, vlnd
Blight end northerly
Bright eunny, aouthvaeterly vinda atrong, wave eaplidude
8-10"
Clear and bright, few elouda, light breeze, vavea 2-9"
Clear to partly cloudy, alight northerly vlnd,
vavaa 2-3"
*NOIT:
Subaequently In April and May 1470 readtwa Ineruud to 4.0-5.H
ft below veter eurfece.
25
-------
TABLE 3 (Continued)
1
Date
Ap£
15
23
30
May.
7
19
27
Jun
l>
16
25
Jul
1
7
16
21
50
Aug.
7
14
18
19
26
Sep
It
10
17
23
2
Time
of
Day
(hours)
1200
1100
1230
1250
1115
1220
1225
121(0
1230
1145
1235
1245
1420
1150
1400
1330
1315
1330
1235
1250
1415
1230
1JOO
3
Secchl
Depth
(meters)
5.89
5.83
5.80
it. 88
4.12
1.65
3.75
2.53
3.97
5.22
5.47
4.27
3.2it
1.69
1.^6
2.16
2.62
2.1*!
2.26
2.04
2.93
4.15
5- "O
It
Water
Depth
(ft)
55-5
55.6
55.6
55.8
55.5
55-5
55.3
54.9
54.8
54.4
54.0
53.8
53.6
50.7
49.2
48.0
47.4
47.2
46.9
44.7
43.9
44.0
44.1
5
Water
Temp.
(•c)
10.0
10.5
9.5
14.0
13.4
16.5
19.5
15.5
20.5
18.5
21.0
21.0
22.5
20.8
20.8
21.7
21.8
21.3
20.0
17.7
18.2
16.3
15.0
6
Air
Temp.
CO
7.0
9.5
11
18.0
15.7
16.5
26.5
19.5
23.5
23.5
23.0
17.4
;j6.o
23.0
S6.S
27.0
27.0
27.5
23.0
S5.0
28.0
23.0
25.0
7
Light
Intensity
(ft-c)
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
8
Remarks
Partly cloudy, numerous mosquito-like insects on water
surface.
Snow, partly cloudy, floating chunks of al^ae observed
near shore.
Clear sky, partly cloudy, slight ripple, approximately
75-100 vater fowl.
Clear sky, numerous fishermen, floating chunks of algae
all over surface.
Pertly cloudy, windy, veil mixed, few swallows, black
birds on shore.
Partly cloudy, several fishermen, slight breeze gustlng at
times.
Clear sky, partly cloudy, approximately 25 fishermen, 2
boats, lake smooth, outlet open.
Clear sky, cloudy, numerous campers and fishermen, 2
bosts.
Cloudy, 8 fishermen, approximately 25 water fowl, 4 cows
grazing.
Clear sky, numerous sportsmen, black snails noted near
dam.
Clear sky, partly cloudy, slight northerly, 15 to 20
fishermen.
Clear sky, outlet open, moderate south westerly, 6" to 8"
waves.
Clcnr uky, portly cloudy, brink westerly, numerous fich-
ermun, one bont.
Clear sky, white precipitate on dam indicating water level
drop, decrease on south end indicated by al£na nnd mud.
Clrnr nky, block algal cruat on bouyu, strong south
westerly.
Clear sky, "no overnight camping" signs posted, few gulls,
6 ducks.
Clear sky, partly cloudy, light wind from the south, 24 hr
sampling trip.
Clear sky, partly cloudy, water level low exposing consid-
erable benthie plants.
Clear sky, partly cloudy, approximately one dozen 10" to
16" catch observed from boat, fishermen, 100+ water fowl
of various species, 3 boats.
Clear sky, few fishermen, no boats, strong southerly
approximately 30+ mph.
Clear sky, slight to moderate southerly, i'ev fishermen.
Clear sKy, flying insects a nuisance, Daphnla noted in DO
samples.
Clear sky, approximately 10 fishermen, 2 boats, small
flock of water fowl, Dnphnia still noted.
26
-------
TABLE 3 (Continued)
1
Date
Oct
1
9
1U
22
28
Mov
6
11
18
2U
Dec
9
15
Jan 1971
6
27
Feb
10
22
Mar
9
15
2>l
AH
5
19
Majr
5
17
2
Tljne
of
Dny
(hours)
1230
1235
1215
1225
1200
1S30
1335
1200
13OO
1400
lll>5
1215
1150
1315
1215
1300
1255
li'50
1130
llUO
1155
1230
3
Secchi
Depth
(meters)
5.62
5.83
6.13
It. 06
6.53
3.51
4.27
5.50
-
}.54
4.58
5.19
5.50
1.83
1.55
1.22
1.07
u.y?
0.79
1.65
5.96
-
it
Water
Depth
(ft)
4J.5
U4.0
44.0
44.2
44,4
44.9
45.0
45.1
"15.3
U6.7
46.9
48.0
"19.6
50,0
50.6
51.0
51.6
51.7
52.1
52.5
53.0
53.2
5
Water
Temp.
(•0)
14.3
13.0
13.0
9-5
7-5
7.0
7.4
6.8
7.8
2.8
2.7
2.9
4.0
5.5
5.0
4.5
k. 9
'i.'J
10.0
10.2
12.0
14.0
6
Air
Temp.
(•c)
?>.o
21.5
19.0
9.5
14.0
6.0
11.0
8.5
19.0
6.0
12.0
-3.0
9.5
17.0
6.0
11.0
10.0
11.0
19.5
15.5
16.0
16.0
7
Light
Intensity
(ft-c)
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
.
-
-
-
-
-
-
8
Remarks
Clear sky, surface glassy, thousands of bl^ck snails,
approximately .60 mm dia . collected In dredge.
Clear sky, partly cloudy, approximately 10 fishermen,
observed several catch 12" to IV.
Clear sky, approxijnately ?OO coots, numerous fishermen,
1 boat, numerous Daphnia.
Clear 3ky, partly cloudy, strong southerly, 8" to 10"
vaves, U or 5 fishermen.
Clear sky, partly cloudy, large Daphnia at 8 ra, approxi-
mately 6 vehicles, 2 rubber rafts, 1 motor boat.
Rain, snow, strong south westerly, appears to be veil
mixed.
Partly cloudy, strong south westerly, 8" to 12" vaves,
approximately 15 vehicles with fishermen*
Clear sky, partly cloudy, fishing season closed, coot
population diminished considerably.
Clear sky, partly cloudy, strong south westerly, too windy
to launch, grab samples taken.
Clear aky, several, fish Jumping, numerous deer tracks
along rond, £ hunters.
Clear sky, partly cloudy, 1/2" ice in middle of lake,
aeratorc Just turned on.
Clear sky, entire lake frozen, approximately 7" ice,
aerators not working, numerous deer tracks.
Clear sky, lake approximately 50 percent frozen with
approximately 1" ice, slight northerly wind.
Clear sky, extremely green cast over entire lake, no vind.
Cloudy, green cast over entire lake, vind southwest at
approximately 5 mph.
Cloudy, 6" to 8" waves, approximately 50 coots.
Clear oky, partly cloudy, 2" to 3" waves, no water fovl
oniirrvnd.
IVirtiy cloudy, Krorn c:iuit, over Inkc, ocvcrul opecieo of
birdu and water fowl, 3" to 5" wavco.
Clear sky, partly cloudy, green cast over lake, two ducks
observed.
Clear sky, slight ripple, approximately 50 ducks, numerous
flying chlronomus near shore.
Partly cloudy, approximately 10 anglers, approxtaately 25
water fovl, slight ripple.
Clear sky, numerous birds of several varieties, several
fishermen.
At one ft below water surface.
-------
ro
oo
FIGURE 3. CLARITY OF INDIAN CREEK RESERVOIR. (SECCHI DISK)
Apr May June July Aug Sept Oct Nov Dec
June
1970
Jan F*b Mar Apr May June July
B7I
FIGURE 4. VARIATION IN SURFACE WATER TEMPERATURE (TOP 1/2 METER). INDIAN CREEK RESERVOIR
-------
range, with southwesterly or northwesterly winds most common. Only on rare occasions
was the water surface free of ripples or waves due to wind, a fact which undoubtedly
reduced the clarity as measured by the Secchi disk. The roughest water observed
resulted from strong southwesterly winds in October and December, and from northerly
winds in March.
Wind movement across the reservoir undoubtedly has an important effect on mixing of
the reservoir. From Figure 2 (Section IV) it may be seen that a southerly wind
roughly parallels the long axis of the reservoir, moving from the shallowest water
towards the dam. Waves induced by such wind action then tend to stir up sediments
in the shallows and, if of any duration, to pile up water at the deepest end of the
reservoir. Subsequent movement of water is therefore from the reclaimed water inlet
(near the dam) to the shallow southerly end of the pool. A northerly wind, of
course, develops a seiche that results in a return flow to the dam when cairn is
restored. Southwesterly winds blow toward the lake shore northeast of the dam (see
Figure 2) and, because of the protection of a high ridge at the west abutment of the
dam, can be expected to initiate a counterclockwise movement of surface water in the
reservoir. This should have a mixing effect, at least in the deeper portion of the
impoundment north of an east-west line passing through the saddle dam. It is con-
cluded that the well mixed condition found to exist in Indian Creek Reservoir is to
no small degree a result of wind movement and direction.
Some more general environmental factors of ICR were presented in Section III.
Initially the reservoir site was remote from human activity, with only cattle and
deer grazing in what is now its shallowest portion. Such domestic and wild animals
continue in the area, but as noted in Table 3 the reservoir has proven extremely
attractive to fishermen and harbors various species of wildfowl.
CHEMICAL OBSERVATIONS
Daily observations of the chemical and bacteriological quality of reclaimed water
exported to Indian Creek Reservoir by the South Tahoe Public Utility District were
compiled by the District from the beginning of export March 31, 1968 and reported
on a monthly basis thereafter. Analyses of the impounded water were begun by the
LTAC Laboratory on October 3, 1968, prior to the beginning of the EPA Indian Creek
Reservoir Demonstration Grant, as a part of ongoing studies of eutrophication of
surface waters likewise supported by the EPA [5], Beginning in April 1969, analysis
of the exported reclaimed water was made also by the LTAC Laboratory as a part of
its weekly sampling program at Indian Creek Reservoir. Analysis of surface and
ground waters in the vicinity of the reservoir made by the California Department of
Water Resources have been reported [k],
BOD and COD
From results of BOD analyses obtained during the first year of study [k] it was
evident that the Biochemical Oxygen Demand of the reclaimed water exported to
Indian Creek Reservoir (ill) was extremely low, averaging only about one mg/,0.
Therefore routine BOD examinations of reservoir influent were discontinued in
March 1970.
Values of COD in the influent and impounded water of ICR are reported in Table 1J of
Appendix. Due to an imperfection in laboratory technique, COD data collected prior
to June 1970 are considered unreliable and are therefore not summarized in Figure 5.
From the figure it is evident that there was little difference in influent and
impounded water in terms of COD. There is, however, a slight tendency for the
impounded water to be higher in Chemical Oxygen Demand, especially during the spring
growing season when, as noted in relation to clarity (Figure 3), the presence of
algae in the impounded water was evident.
-------
100
Apr ' May ' June ' July ' Aug 'Sept ' Ocl ' Not 'Dec \ Jan ' Feb ' Mar ' Apr ' May ' June ' July
1970 B71
FIGURE 5 VARIATION IN COD. INDIAN CREEK RESERVOIR
Suspended Solids (SS)
Results of the suspended solids analysis reported in Table 13, Appendix, were ana-
lyzed both in terms of clarity versus SS and variation in SS with time and season.
In Figure 6 are plotted Secchi disk readings in relation to suspended solids in the
impounded ICE water at the time of reading. Although there is a variability in
clarity at any given SS value, which is explainable in terms of water surface dis-
turbance and other variables, the general curve takes the form to be expected of a
clarity-turbidity relationship. At levels of SS below about 2 TQQ/& this relationship
is no longer evident. However, considering the nature and limitations of the Secchi
disk test it is perhaps surprising that the relationship continues to be evident at
such low concentrations as appear in Figure 6. Comparison of Figure 3 with Figure 7
reveals the expected inverse relationship between water clarity and suspended solids
in the impounded water, the lowest Secchi disk reading appearing at times when peaks
occurred in the SS curve.
The correlation coefficient for suspended solids versus reciprocal clarity was found
to be 0.88 and the regression coefficient was 25 mg SS/0/ft Secchi disk depth. When
the data on SS were segregated into two groups (> 50$ VSS, and < 50$ VSS) it was
found that although the correlation coefficients were comparable (0.93 and 0.87,
respectively), the regression coefficients were quite different, varying from 31 mg
SS/^/ft for the > 50$ VSS material to 21 mg SS/e/ft for the < 50$ VSS material. Thus
considerable effect of the presence of algae as VSS on the relationship between SS
and Secchi depth occurs, probably because of the absorption of the longer wave lengths
of light (red) by green algae.
Figure 7 presents the suspended solids data on a time sequence for the period of stud]
As previously noted, the general similarity of impounded water (C) and reservoir
discharge (B) justified dropping the latter from the sampling schedule in March 1970.
As might be expected, the reclaimed water tended to be reasonably constant in sus-
pended solids content except for an occasional peak. Nevertheless, during the period
April 1970 to May 1971 it varied from a low of O.^J mg/^ to a high of k.kj mg/,0.
During this same period the SS concentration in the impounded water varied from 0.66
mg/^ to 9.07 mg/,0.
The excess of SS in impounded water over that in reclaimed water is most impressive
in the early growing season (January to March) of each year. The effect of climato-
logical factors on the suspended solids in the reservoir is evident in the data for
October 1969 and again in November 1970. In the first instance (see Table 3) heavy
-------
SECCHI DISK DEPTH, maters
12.0
10.0
!•»
s
CO
o
z
Ijl 6.0
iS
CO
4.0
2.0
(
a i 2 34
, , , 1 — , , 1 | | |
i
1
i
I
\
•\
\
\
i
\
\
\o
\
\
t \
• V «
10 • Data from Ap
• O M H H
» 0 •
\ •
\
A
— * \ o
\
>Q
\o 0 °
N »0 0
. 0 ^ • °
* • o^^. *> o o
• "t>"~-—- ._ ° o o
• . rr~~; — ~—
t 0 °
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
}| 2 3 4 5 6 7 8 9 10 II 12 13 14 15
5 6
-
~
.
r» 1969-April 1970
1970 - " 1971
-
-
o
° — o
o o Q J> ~ ~
° o O O
o
0 o
1 1 1 1 1 1
16 17 18 19 20 21 22
SECCHI DISK DEPTH, feet
FIGURE 6. CLARITY OF WATER (SECCHI DISK) AS A FUNCTION OF SUSPENDED SOLIDS
-------
14.0
Mar Apr May June July Aug Sept Ocl No* Dec Jan Feb Mar Apr May June Jdy
ro
FIGURE 7 VARIATION IN SUSPENDED SOLIDS, INDIAN CREEK RESERVOIR
C - Impounded Water
B - Discharged Water
- Influent Reclaimed Wafer
June
FIGURE a VARIATION IN VOLATILE SUSPENDED SOLIDS. INDIAN CREEK RESERVOIR
-------
winds prevailed at the reservoir. In the latter instance winds were too strong to
permit launching of the sampling "boat and data had to be taken from a grab sample
obtained near the shore.
Volatile Suspended Solids (VSS)
Figure 8 shows a tendency for the VSS in the impounded water to be like that of the
influent reclaimed water except during the spring growing season and on a few other
less obviously explainable occasions. Thus VSS, as might be expected in a situation
such as Indian Creek Reservoir, tends to follow the same pattern as the total sus-
pended solids (SS). A comparison of Figure 8 with Figure 7 shows this generally to
be the case. However, a careful analysis of Table 13 (Appendix) shows that on
several occasions the SS/VSS ratio was greater than normal (e.g., 5 to 1). Reasons
for this variation are not fully documented nor self-evident. It may well be that
wind disturbance, together with pulses in the aquatic community, are the principal
factors. At any rate on 8 of 13 occasions when the SS/VSS ratio exceeded J to 1
strong winds were blowing at the time of sampling. On three other occasions the
winds were light; and on two occasions no apparent cause was identified. In as
much as wind conditions at Indian Creek Reservoir are unpredictable and no continuous
wind records are available, and the VSS levels involved are only in the 1 to 2 mg/£
range, there is nothing implausible about the observed variation in SS/VSS ratio
although its causes are not fully identified.
Iron
The iron content of influent reclaimed water averaged higher than that of the
impounded water. Because iron was measured in filtered samples, such a condition
could result from the taking up of influent iron by living cells or by precipitation
of iron from the impounded water. The former would indicate that iron is an important
factor in the production of biota in the reservoir, whereas the latter would be of
little significance. Further evidence may be derived from a study of Figure 9.
Figure 9 shows that the concentration of iron in influent and impounded water was
variable, particularly on a seasonal basis, being higher during the summer months
when the visitor load on the Lake Tahoe Basin is greatest. Analysis of raw sewage
at the STPUD'plant [lU] in 1968-69 shows clearly that the waste water is much more
concentrated in summer than in winter. For example, total nitrogen on June 25, 1968
was 42 mg/£. On January 18, 1969 it was but 17 mg/,0. Similar reductions were
observed in other constituents of the raw sewage.
From June to November 1969 there was a tendency for the impounded (C) and discharge
water (B) curves to parallel each other, but little tendency to follow the pattern
of influent iron (ill). The greatest concentration of iron in the reservoir water
was observed in June 1969 coincident with similar high concentrations in SS and VSS.
Again in the spring and summer of 1970 the concentration of iron tended to follow
the same pattern as that of suspended solids. This indicates that the presence of
iron was related to the solids. However, because iron was measured in a filtered
sample it could not have been incorporated in algal cells, although it may have
been in the recycling process.
After June 1969 there was a pronounced tendency of iron to decrease when SS and VSS
increased. This suggests that iron may have been an important factor in the pro-
duction of biota in the reservoir during the growing season. During the winter of
1969-70 it is not clearly evident where the iron was located in the system. Most
likely the summer input of iron was tied up in dead cells on the reservoir bottom
and the impounded water reflected the influent iron concentration unchanged for
lack of biological activity at the low temperatures of winter. Thus there is
evidence that iron in the influent water is utilized in the biological cycle of
Indian Creek Reservoir, although there is no evidence that it is a limiting element.
33
-------
Jura
Sept
FIGURE 9. VARIATION IN IRON CONCENTRATION. INDIAN CREEK RESERVOIR
Jura
Apr May June July Aug. Sept Ocl Nov Dec | Jan Ftb Mar Apr May June JJy
1970 1971
RGURE 10. VARIATION IN CHLORIDE CONCENTRATION, INDIAN CREEK RESERVOIR
-------
Chlorides
Figure 10 shows that the chloride concentration of the reclaimed water generally
exceeded that of the impounded vater prior to about September 1970 as the reservoir
was filled and became somewhat stabilized. In September the two were essentially
equal and remained so until the spring of 1971 when the Impounded water concentration
curve became slightly the higher of the two. In numerical terms the chloride concen-
tration of influent reclaimed water averaged 27 mg/e during the first period (April
1969 through March 1970) and 29 as/I during the corresponding 1970-71 period of study.
Chlorides in the impounded water during these same time periods averaged 22 mg/£ and
26 mg/jj, respectively. Thus 5 mg/J separated the reclaimed and impounded water
chloride concentrations during 1969-70 and only 3 mg/4 during 1970-71.
In as much as chloride is a conservative material in biological systems, the observed
difference in concentration of the reclaimed and Impounded water is presumably due
to a combination of surface runoff and evaporation after the initial leaching from
underlying soil. It is difficult to estimate how much chloride may have leached
from the disturbed soil during the initial reservoir filling operation. Normally,
however, the chloride concentration in precipitation and surface runoff from
undisturbed land is less than 2 mg/0. Therefore it appears that the chloride concen-
tration of the impounded water is principally a function of that of the reclaimed
water plus the concentrating effect of evaporation.
Variations in the pH of reclaimed and impounded water reported in Table 13, Appendix,
are shown graphically in Figure 11. In general, the two waters showed very little
difference in pH. However, because pH is the negative logarithm of the hydrogen
ion concentration it requires a tenfold concentration difference to change the pH
by one unit. Therefore the parameter is much less sensitive than other chemical
parameters.
It is to be expected that during periods of extensive algal growth, free carbon
dioxide will be utilized at such a rapid rate that the, pH will show an increase.
Such an increase is evident in Figure 11 during the February to April 1970 period,
although somewhat less apparent during the equivalent period in 1971. Throughout
the period of study the pH of the impounded water remained close to 8.0, indicating
that Indian Creek Reservoir was in a healthy condition limnologically.
Conductivity
Values of conductivity observed during the period of study are summarized in Figure
12. The same slight tendency for an increase with time previously noted in relation
to chlorides is evident in the conductivity of both reclaimed and impounded water.
However, a consistent drop in conductivity is apparent throughout the period of study
as reclaimed water was mixed with the impounded water which .included both surface
runoff and effluent from the STPUD plant. Table 13 (Appendix) shows that the
conductivity of impounded water ranged from 229 to 530 n mhos/cm at 25°C. This is
within the 0.25 to 0.75 m mhos/cm range reported by Eldridge [15] to characterize
about half of the irrigation waters used in the western U. S. It is also in the
range where the salinity effects are reported by the USDA [l6] to be mostly negligible
on field, vegetable, and forage crops.
It is therefore concluded that in terms of conductivity, water impounded in Indian
Creek Reservoir is of good quality for its current use in irrigated agriculture.
Calcium
Figure 13 summarizes the concentration of calcium observed in reclaimed and Impounded
water at Indian Creek Reservoir during the period herein reported. As in tjhe case
of other quality factors observed, transient fluctuations in the " influent concentra-
tion are damped out in the mass of impounded water. The influent concentration is
characteristically high, and the impounded water and discharged water curves are close
35
-------
9.0
8.S
ao
I 7.5
a.
T.O
6.5
6.0
i i i i i i - 1 - 1 - 1 - 1 - 1 - 1 - 1 - 1 - 1
1 - 1 - 1
C - Impounded Water
B - Discharged Water
L-M - Influent Reclaimed Waler
• Note Scale Change
Mar 'Apr 'Moy'june'July'Aug 'Sept ' Oct Nw Dec i Jon FebMv Apr May June July
June
Nov Dec | Jon Feb
1970
B71
FIGURE II. VARIATION IN pH. INDIAN CREEK RESERVOIR
AprMtyJumJ^&igSeplOctNovOecJanFtbMarAprMayJwJuly
Jum
FIGURE 12. VARIATION IN CONDUCTIVITY, INDIAN CREEK RESERVOIR
-------
together except when some unusual event occurred, i.e., in August and September
1969, for example, when water was released for irrigation use at a rate of some
four times the influent rate. Analysis of the dicharged water (B) was not performed
during the second period of study (April 1970 - May 1971) "because, as noted in a
preceding section, it was not significantly different than impounded water.
The question of whether dilution alone, or dilution plus precipitation of calcium
carbonate or calcium phosphate, accounted for the difference in calcium concentra-
tion in influent and impounded water was explored [h]. The conclusion, based on
hydrologic calculations, was that dilution rather than precipitation of calcium
was the major factor.
Alkalinity
Variation in the alkalinity of ICE waters is summarized in Figure 1^. Variability
of the influent reclaimed water is again evident; and impounded and discharged
water were generally the same during the period when both were measured except that
the relationship was disturbed during the August 1969 release of water.
The figure shows an upward trend in alkalinity with time over the period of study.
That this is a function of treatment plant operations in precipitating phosphorus
with lime and restabilizing the water is shown in data on raw sewage at the STPTJD
plant. Here, for example, an increase in alkalinity from 192 mg/.g in the raw
sewage to 221 mg/g in the reclaimed water was reported [9] for June 25, 1968. On
January 18, 1969 this increase through the treatment plant was from 8^ mg/0 in raw
sewage to 208 mg/,0 in the plant effluent.
As in the case of both chlorides and calcium, there is an appreciable difference
between the influent alkalinity curve and that for the impounded water. As before,
this brings up the question of the role of dilution in reducing concentration. In
comparing observed values of alkalinity as of December Jl, 19^9 with values computed
from a water balance for the reservoir it was found [k] that dilution accounted for
only 83 percent of the observed reduction from reclaimed to impounded water.
Assuming the previous conclusion to be correct, that dilution alone accounts for the
decrease in calcium, precipitation of calcium carbonate is ruled out as a possible
cause of the apparent loss in alkalinity. Nor is precipitated CaCOa in the recarbon-
ated reclaimed water the answer, because both the calcium and alkalinity data were
obtained from filtered samples. Alkalinity in the exported reclaimed water is in the
bicarbonate form as a result of recarbonation at the STRJD plant. However, no analyses
were made for sodium or magnesium, hence it is impossible to be certain that all the
alkalinity is accounted for by any study of the data on calcium. It is therefore
necessary to look carefully into the matter of inorganic carbon.
Inorganic Carbon
Figure 15 shows the inorganic carbon content of reclaimed and impounded waters.
Inorganic carbon values were computed on the basis that carbon present in the in-
organic form is in the bicarbonate radical of alkalinity. The computed values,
therefore, are not only a function of alkalinity but also vary with the pH and
temperature. As in the case of alkalinity the difference in concentration of
inorganic carbon (Figure 15) between influent and impounded water cannot be
attributed to dilution alone. The difference between the observed and the computed
inorganic carbon in the impounded water leads to the inescapable conclusion that
bicarbonate alkalinity was used as a source of carbon by the biota of Indian Creek
Reservoir during the period of study.
Phosphorus
Phosphorus removal at the STPUD plant is a highly efficient process, reducing the
concentration in the reclaimed .water to a level which seldom exceeds 500 ug/,0.
Removal is achieved by lime precipitation followed by recarbonation to precipitate
the excess calcium carbonate. Table h shows that during the first period of study
(April 1969 - March 1970) the total phosphorus content of the reclaimed water
37
-------
FIGURE 13. VARIATION IN CALCIUM CONCENTRATION. INDIAN CREEK RESERVOIR
CD
1 ! 1 1 1 1 1 1 1
C - Impounded Water
B - Discharged Water
L-tt - Influent Reclaimed Water
Apt May June July Auo. Sept Ocl No. Dec I Jan Feb Mar An May June July
Jun*
FIGURE 14. VARIATION IN ALKALINITY, INDIAN CREEK RESERVOIR
-------
averaged 1^8 v&/& and orthophosphate (PO^-P) averaged 126 ^g/^. For the second
period of study (April 1970 - May 1971) these same constituents averaged 119 and
86 v&l&, respectively. Thus it appears, assuming that the raw sewage was of approxi-
mately of the same quality over the two study periods, that the efficiency of
phosphorus removal improved at the STPUD plant as time progressed.
TABLE k
SUMMARY OF CHANGES IN NUTRIENT CONCENTRATION, INDIAN CREEK RESERVOIR
Sample
Influent
(L-III)
Indian
Creek
Reservoir
(c)
Influent
(L-III)
Indian
Creek
Reservoir
(C)
Period
April 1969
through
March 1970
April 1970
through
March 1971
Mean Concentration of Nutrients fjg/,0
NH3-N
17,9^2
3,^39
19,588
3,810
(NOa + N03)-N
66k
2,893
295
3,3^9
Total-N
19,313
7,241
20,395
8,09^
PQi-P
126
37
86
lU
Total-P
11*8
51
119
27
Total phosphorus in the impounded water during the first period was 51 \s&/& and
orthophosphate was 37 uS/^j whereas during the second period these two constituents
averaged only 27 (jg/# and 1^ (jg/^, respectively. Variations in the concentration
of orthophosphate in ICR waters over the full period of study are shown graphically
in Figure 16. Total phosphorus for the same waters over the same time period are
shown in Figure 17.
The difference in phosphorus concentration in reclaimed and impounded water is only
partially accounted for by dilution. Phosphorus is a nonconservative material in
that it enters into life cycles and may spend a good portion of the cycle in the
benthic sludge or in living cells, hence it cannot be accurately traced by the
dilution approach applied to conservative elements. From Figure l6 there appears
to have been more orthophosphate in the impounded water during the winter than
during the summer seasons, especially in the second period of study. This is
explainable because winter temperatures limit the ability of biota to increase and
thus they cannot utilize the available phosphorus. From both Figures l6 and 17 it
seems evident that especially during the second period of study phosphorus must
have been the nutrient generally limiting to biota of Indian Creek Reservoir. This
relationship, however, is further considered in a subsequent section dealing with
the results of bioassays.
Organic Nitrogen
Organic nitrogen is the only major quality factor herein discussed in which the
concentration in the impounded water fluctuated as wildly as did that in the
influent reclaimed water. Biological processes are used in the reclamation process.
They are followed by precipitation, filtration, and carbon adsorption. Nevertheless,
the reclaimed water is far from a uniform product in terms of organic nitrogen
39
-------
June
FIGURE 15 V0VRIATION IN INORGANIC CARBON, INDIAN CREEK RESERVOIR
FIGURE 16 VARIATION IN CONCENTRATION OF ORTHOPHOSPHATE, INDIAN CREEK RESERVOIR
-------
content. The data plotted In Figure 18 show that in summer there was a very rough
tendency for the influent and impounded water curves to peak simultaneously. In
the fall the reverse was the case. In December 1969, for example, the greatest
concentration of organic nitrogen was in the reservoir water but in January 1969
it was evidently in the benthic stratum. There was a definite tendency for higher
than average organic nitrogen concentration to prevail in impounded waters during
the summer and fall months, and less than average in the winter. This is in accord
with an observed tendency for Indian Creek Reservoir to support aquatic growth, and
hence to produce a significant quantity of organic nitrogen which more than offset
any dilution effect.
On the basis of Figure 18 it must be concluded that although there is nothing
unexplainable in the behavior of the organic nitrogen curves, organic nitrogen is
not a good parameter by which to describe the limnology of Indian Creek Reservoir.
Ammonia
Figure 19 summarizes the variation in the ammonia content of the reclaimed and
impounded waters during the period of study. As in the case of most other water
quality factors discussed in preceding paragraphs, the transient fluctuations in
concentration characteristic of the influent water are damped out in the impounded
water in the reservoir. From the figure, and from Table k, it is obvious that only
a minor fraction of the difference in ammonia concentration between influent and
impounded water can be accounted for by dilution. For example, the influent
reclaimed water had an average ammonia content of 17,9^2 i&/£ during the first
period of study and 19,558 pig/4 during the second. At the same time the averages
in impounded water were but 3,^39 ugA and 3,810 |og/^, respectively.
The mechanisms by which ammonia is so drastically reduced in Indian Creek Reservoir
from influent to resident impounded water are perhaps the most important phenomena
in the quality of ICR water. They represent the difference between a water defi-
nitely inimical to fish life and one in which fish have flourished for more than
2 years. They are discussed herein in greater detail in relation to the biological
observations at Indian Creek Reservoir.
Nitrite Plus Nitrate Nitrogen
Table 13, Appendix, shows that the values for nitrite nitrogen averaged less than
10 percent of those for nitrate nitrogen. -' Consequently the two forms of nitrogen
are combined for presentation in Table k and Figure 20. As was the case with
organic nitrogen, biological activity more^than overwhelmed the dilution effect
with the result that the influent nitrate-nitrite nitrogen was only a small fraction
of that present in the reservoir. These vastly greater concentrations appearing in
the impounded water are largely due to the oxidation of ammonia by biological
activity in the reservoir. They may also be a pathway by which ammonia is removed
from the reservoir via nltrification-denitrification phenomena.
Total Nitrogen
Figure 21 and Table U show that the total nitrogen In the influent reclaimed water
is comprised mostly of '.ammonia, whereas in the impounded water the total is only
about 50 percent ammonia. In both cases the average has increased slightly with
time; a trend, which if continued over a period of years in parallel with a
decreasing concentration of phosphorus, could have a profound influence on the
biota of Indian Creek Reservoir.
Dissolved Oxygen
Dissolved oxygen data for Indian Creek Reservoir waters throughout the period of
study are presented in Table 13, 'Appendix. Variation in DO with depth below the
water surface is shown for periodic sampling dates during the 1969-70 study period
and at approximately weekly intervals during 1970-71 period. From the table it
may be observed that the dissolved oxygen content of the influent reclaimed water
-------
sj
o>
1,000
900
800
700
600
500
400
300
200
100
0
C - Impounded Water
B - Discharged Water
L-I - Influent Reckoned Water
•*» Apr May June JJy Aug ' Sept ' Oct ' Nw ' Dec
Jon Feb Mar Apt May Jura July
June
FIGURE 17 VARIATION IN CONCENTRATION OF TOTAL PHOSPHORUS, INDIAN CREEK RESERVOIR
Apr May June July Aug Sept Oct No, Oecljan
FIGURE 18. VARIATION IN CONCENTRATION OF ORGANIC NITROGEN, INDIAN CREEK RESERVOIR
-------
32,000
i—i—i-—II
'so* ' Oct ' Nov Doc I
Jan Feb Mar Apr May Jim July
JUM July Aug Sept Ocf No» OK
1969
Apr May Jww
1970
FIGURE 19. VARIATION IN CONCENTRATION OF AMMONIA, INDIAN CREEK RESERVOIR
Apr May Jtra July Aug Sept Oct Nov Dec I Jon Feb Ma
FIGURE 20. VARIATION IN CONCENTRATION OF NITRATE + NITRITE NITROGEN. INDIAN CREEK RESERVOIR
-------
was constantly less than 2 mg/,0 except on a few occasions which may well be in error
due to problems of sampling from a pressure outfall line without aerating the
sample.
Figure 22 shows that throughout the entire period of observation the impounded water
in the top half-meter was near or above saturation, varying normally with water
temperature. One notable exception appears in late October 1969, when an extremely
high value of DO was observed.
Figure 3 has shown that the impounded water was exceptionally clear at that time
and Figure k showed that the temperature stood at 9°C. Thus an unobserved algal
bloom could not have been the cause. Attempts were made to discover whether any
unusual event had occurred. Table 1^, Appendix, shows that as early as September 15,
1969 the reservoir vas well mixed vertically and on November 19 of that year both
good mixing and high (9 + rag/6) DO characterized the Impounded water. Although a
recheck of data and discussions with the personnel involved failed to reveal any
identifiable error, it was concluded [4] at the time that some malfunction of the
analytical procedure was the only logical explanation of the DO peak in October 1969.
Table l4 also shows that in July 1969 the dissolved oxygen in the vertical profile
of the reservoir ranged from 7-6 mg/,0 at 0.5 meters below the water surface to
0 mg/0 at 0.5 meters above the reservoir bottom. By September 1969, however, the
dissolved oxygen profile at all three of the sampling stations (Figure 2, Section
IV) revealed a well mixed water mass both vertically and horizontally, with a
reduction in concentration of oxygen in the upper strata as a result of mixing with
underlying oxygen-poor water.
By mid-November 1969 all quality factors reported in Table 13 (Appendix) were
essentially uniform from surface to bottom of the reservoir water. At that time a
sampling at the three stations showed that the DO ranged from 8.6 to 9.6 mg/£ in
the entire water mass sampled. Table 14 shows that this well mixed condition
continued in February 1970, at which time the DO had risen to 11 ± mg/,0.
In March of 1970 mechanical aeration was initiated but was interrupted after only
about 10 days of operation until June 25. In the interval, in May 1970> an oxygen
profile began to develop. By early June it showed a DO range of from 11.1 mg/g at
-0.5 meters to l.U rng/0 at -10 meters. However, a well mixed condition developed
by June l6, before the artificial aeration system was restored. Thereafter, as
the weather warmed up and aeration was practiced, oxygen profiles were less pro-
nounced until mid-July when the steep oxygen profile of the preceding July was
essentially repeated, albeit with a low of 1.5 mg/,0 instead of 0 mg/£ as before.
A second period of low oxygen in the bottom stratum occurred in August. Then from
September 1970 to the end of the report period in May 1971 the DO in impounded water
vas at or above saturation throughout the vertical profile.
From the data observed, the exact effect of artificial aeration of Indian Creek
Reservoir is obscure. Both before and after installation of the system, periods
of complete mixing and strong stratification occurred. In general it appears that
the oxygen depletion at the bottom of the reservoir was less severe and DO concen-
trations under well mixed conditions were somewhat higher after operation of the
aerator began.
Nutrient Inventory
An inventory of several selected parameters, with special concern for nutrients, is
presented in Table 5 for the two periods of study herein reported. Hydrologic data
summarized in the table are the same as those presented in Table 2 with two
exceptions. Loss by evaporation was omitted because the amount of chemicals trans-
ported by evaporation is insignificant in comparison with the amounts present in the
reclaimed or impounded water; and water lost from the impoundment by percolation and
by leakage through the outlet valve were combined into a single volume. The
arithmetic signs (+ and -) shown in column 1 of Table 5 pertain to the inventory
equation expressed in the form: An = I + RO + PL - D - PQ - Vo - AS, in which An
kk
-------
I 1 1 1 1 1 1 1 1 1 1 1 1
C - Impounded Water
B - Discharged Water
- Influent Reclaimed Water
Mar Apr May June July Aug Sept Oct Nw Dec I Jon Feb Mar Apr May June July
Jura .My Aug S»pt Oct Nw 0«c
1969
FIGURE 21. VARIATION IN CONCENTRATION OF TOTAL NITROGEN, INDIAN CREEK RESERVOIR
Stpt Oct Nor Doc | Jon Feb
FIGURE 22. VARIATION IN DISSOLVED OXYGEN, INDIAN CREEK RESERVOIR
-------
TABLE 5
INVENTORY OF SELECTED PARAMTERS OF INDIAN CREEK RESERVOIR
Time
Period
April
1969
through
March
1970
April
1970
March
1971
Total Water Volumes Per year
Location
(I) Influent from ;+)
STPUD
(Pt ) Precipitation (+}
Directly on
Reservoir Surface
(BO) Surface Runoff W
(D) Irrigation (-)
Discharge
(P + V ) Percolation (-)
+ Discharge
Valve Loss
(AS) A Storage (-)
Total An
(I) Influent from (+)
STPUD
(P ) Precipitation (+)
Directly on
Reservoir
(Estimated)
(RO) Surface Runoff (+)
(Estljaated)
(D) Irrigation (-)
Discharge
(P + V ) Percolation (-)
+ Discharge
Valve Loss
(AS) 4 Storage f ->
Total An
ac-ft
26711
340
1145
522
21*50
800
2687
225
815
241*8
1399
(-1570
Average Cheiaical Values
Nitrogen as M
Organic
ae/l
647
191
99
1005
909
909
525
191
99
922
906
906
kg
2133
80
140
647
2746
897
-1937
1739
53
99
2783
1563
637
-1818
NH3
ug/t
17,942
117
38
3025
3439
3^39
19,711
117
38
3539
}8lO
3810
kg
59,155
49
54
1947
10,389
3592
43,530
65,305
32
38
10,682
6572
2673
50,799
N0a<
at/I
664
56
17
3O43
2893
£893
232
56
17
3059
5349
334?
i- N03
kg
2189
23
24
1958
8739
£354
-11,315
769
16
17
9S33
5777
2354
-11,854
Total
ug/l
19,253
357
154
7073
7241
7241
20,395
557
154
7590
£094
EO;A
kg
63,477
150
217
4552
21,873
7143
30,275
67,571
99
155
22, 910
13,?5£
5688
36,641
Phosphorus as P
P0<
ug/*
126
9
11
2o
37
37
66
9
11
11
14
14
kg
415
11
16
17
112
36
270
285
e
11
33
84
10
251
Total P
ul/l
148
15
23
46
51
51
119
15
23
25
27
27
kg
488
6
32
30
154
50
292
394
i*
23
75
47
19
318
Cl
ng'f
27.4
1.43
0.46
20.6
21.6
21.6
29.2
1.43
0.46
24.7
25-9
25.9
kg
90,338
599
649
13,258
65,249
21,306
-8227
96,743
397
462
74,554
44,678
18,203
-3427
Ca
rug, 'I
57.6
0.5
0.5
43.8
1*1.6
41.6
63.1
0.5
0.5
46.3
47.2
47.2
kg
189,907
210
706
28,190
125,665
4l,034
-4o66
209,057
139
503
139,752
81,420
33,172
21,699
Total S
Total P
Ratio
130
24
7
154
142
142
104
171
Ik
7
304
300
300
115
-------
is the difference in the factor inventoried. A positive value of An indicates that
more material went into the reservoir than is accounted for by the combination of
observations, estimates, and assumptions available for evaluating its fate when
making the inventory (Table 5). Other symbols used in the equation are as defined
in relation to Table 2.
Water quality values for the first time period (April 1969 through March 1970) were
obtained from a previous progress report [U] based on data in Table 13 of the
Appendix (Section Xl). Quality values for precipitation directly on the reservoir
surface were assumed to be representative of the Lake Tahoe Basin [5]. The quality
of surface runoff was likewise considered to be typical of undisturbed areas such as
reported [5] for Ward Creek in the Lake Tahoe Basin. The quality of water released
for irrigation was taken as that prevailing in the impounded water in August and
September 1969, so as to coincide with the actual period of irrigation releases.
Water lost by percolation and leakage through the discharge valve was assumed to
be of the same quality as the impounded water.
For the second period of study (April 1970 through March 1971) values for the several
water quality parameters used in the inventory were obtained from Tables 13 and 15
(Appendix). Quality factors for precipitation on the reservoir surface and for
surface runoff into the reservoir were the same as used for the 1969-70 period.
Irrigation discharge was again averaged for the months of significant discharge; in
this case, June, July, August, and September, 1969 and March 1971. Percolation and
outlet valve leakage were once more assumed to be of the same quality as that
prevailing in the impounded water.
An for organic nitrogen during the first and second periods was -1937 kg and -l8l8
kg, respectively. These two values are quite comparable, probably because of similar
influent reclaimed water volumes during the two periods. The negative sign, of
course, indicates that more nitrogen came out of the reservoir in the organic form
than entered it in that form, as a result of aquatic growth in the impounded water.
Ammonia, the most prevalent form of nitrogen in both the reclaimed and impounded
waters, averages greater than 91*- percent of the total nitrogen in reclaimed water,
and ^7 percent in the impounded water over the two-year period of study. The An
values of ^3,530 kg and 50,799 kg for the first and second study periods, respec-
tively, indicate that the excess of influent over observed ammonia in the reservoir
was relatively similar for the two periods. Because such a large amount of ammonia
was disposed of in some manner from the impounded water, its fate becomes one of
the most important questions in understanding the limnology of Indian Creek
Reservoir.
As in the case of organic nitrogen, the An for the oxidizable forms of nitrogen
(NOa + NOa) for the two study periods were quite similar, with values of -11,315
kg and -11,85^ kg, respectively. The greater output over input in both cases is
apparently the direct result of oxidation of ammonia. This phenomenon, however,
could account for scarcely 25 percent of the untraced ammonia noted in the preceding
paragraph. , .. . . . '
Inasmuch as the values for organic and nitrite plus nitrate nitrogen were both
negative and nearly identical, the resulting Total Nitrogen inventory value would
logically be in about the same ratio but of a lower magnitude. The first period
showed an overall loss of 30,276 kg of total nitrogen, while the value for the
second period was 36,6^1 kg. The overall unaccountable nitrogen loss from the
impounded water is by this analysis therefore greater than ^7 percent for the first
period and nearly 50 percent for the second.
An for both forms of phosphorus - orthophosphate and total phosphorus - were in
approximately the same range for the two study periods. Orthophosphate excesses
were 270 kg and 251 kg for the first and second periods, respectively. At the same
time total phosphorus values were 292 kg and 318 kg.
Some concept of the reliability of the nitrogen and phosphorus inventories herein
presented may be gained by an evaluation of the chloride inventory summarized in
1*7
-------
Table 5- Chloride is considered a major conservative element in vater quality
analysis and thus lends itself to use as a parameter for tracing water movement and
for ascertaining the validity of hydrologic and chemical inventories. For the first
period the chloride inventory value was -8227 kg and for the second period, -3^27 kg.
Although these values of An differ appreciably from each other they represent but a
small percentage of the 90*000+ kg of chloride entering the reservoir with influent
reclaimed water in each of the two periods. Specifically, the first period is out
of balance by only 9 percent; the second by less than k percent. Such a close range
of balance for the two study periods supports the general conclusion that the
hydrologic estimates and measurements, as well as the sampling program for chemical
analysis, are of reasonable validity.
A cursory observation of the calcium inventory of Table 5 shows a first period An
value of -ko66 kg, which is within 2 percent of balancing. The second period value
of +21,699 kg is within 10 percent of balancing, albeit as an excess rather than as
a deficit as during the first period. Although calcium is considered a somewhat
conservative element, it does precipitate out as calcium carbonate under favorable
conditions. A thin layer of calcium carbonate appearing on the rock surfaces at
Indian Creek Reservoir indicates that precipitation is indeed occurring. Thus
precipitation accounts for at least a portion of the missing calcium shown by the
inventory for the second period.
The ratio of total nitrogen to total phosphorus (N/P ratio) in the influent reclaimed
water was of the order of 150 for the first period and 171 for the second period of
study. The impounded water showed N/P ratios of 1^2 and 300 for the two periods,
respectively, again reflecting the increased efficiency in phosphate removal at the
STPUD plant as time progressed. The N/P ratios for the 1969-70 and 1970-71 periods,
based on An values in Table 5> were 104 and 115, respectively.
As previously noted in relation to Table k, the total nitrogen of the reclaimed
water increased slightly with time, whereas the various forms of phosphorus decreased
significantly. This same trend, although more pronounced, was apparent in the
impounded water. From a limnological viewpoint it would be desirable to reverse this
trend and so to produce a more balanced nutrient, although concentrations would have
to be controlled so as not to reach levels sufficient to generate objectionable algal
blooms.
Nutrient Balance
From the preceding discussion, it is evident that during both the 1969-70 and 1970-71
periods of study a large amount of nitrogen and a much smaller amount of phosphorus
was unaccounted for by the inventory presented in Table 5. Moreover, N/P ratios in
influent reclaimed water and in impounded water ranged from 10 to 20 times the 10:1
to 15:1 ratio in which algae normally utilize nitrogen and phosphorus. Thus, unless
there existed some source of phosphorus other than the reclaimed water and surface
runoff, the nitrogen excess computed in Table 5 could not all have gone into the
biota of the reservoir, although some of it most certainly went that route. A second
possibility is that the assumption that percolating water had the same characteristics
as impounded water may be invalid, hence less (or perhaps more) nitrogen may have
left via that route than is estimated in Table 5. A third possibility is that
phenomena not reflected in the inventory computations led to a loss of nitrogen from
the system as gaseous nitrogen, nitrogen oxide, or ammonia, or by accumulation in
benthic sludge. Because all of these phenomena are known to be involved in natural
equilibria, it is necessary to explore the potential of each in any accounting for
the nitrogen loss or estimating of the nutrient balance.
Inasmuch as the TJ/P ratios were heavily out of balance, with nitrogen in the
excess, the limiting effects of phosphorus might be the first factor to consider in
isolating the fate of the unaccounted for nitrogen. The fact that phosphorus is
adsorbed on soil colloids under normal conditions identifies one inaccuracy inherent
in the assumption that percolating water was the same as impounded water in quality.
It also suggests that during the first year of operation, when the reservoir was
being filled, the original soil may have been an important source of phosphorus.
-------
Later, because only a small quantity of water (522 ac-ft) was released for irrigation
during 1969-70, this same phosphorus could have been recycled via the biota of the
reservoir during the second year.
To estimate the significance of soil as a source of phosphorus an analysis was made
of a composite sample of soil taken from 20 locations in the cleared land area above
the shore line in September 1969. Although this soil was typical of the reservoir
bottom and was subsequently inundated as the reservoir level rose, it had been
subjected to one winter's runoff and the steeper sections showed some microvein
erosion. Thus it is possible that the sampled soil may have originally been richer
in nutrients at the time flooding of the reservoir began in 1968, and that the
nutrients lost from it were already in the reservoir sediments at the time of
sampling. To obtain some estimate of the relative magnitudes, however, it is assumed
that the phosphorus content of the original soil was 0.01 mg/g as reported in
Table 6.
On the basis of previous studies of soils [13] it is further estimated that phosphorus
in the top 0.5 cm of soil was available to.benthic organisms. Taking 150 acres as
the area flooded during the year, and assuming approximately ^0 percent porosity of
a soil having a specific gravity of 2.6, it is calculated that some 50 kg of phos-
phorus might have been added to the reservoir nutrient budget by extraction from the
soil. At a maximum N/P ratio of 15:1 this could have tied up only 750 kg of the
more than 30,000 kg shown as excess nitrogen in Table 5 for the 1969-70 period.
Whether or not the biota of the reservoir did make use of phosphorus from the soil,
or whether it remained in the benthic sludge, is a somewhat academic question in
terms of the problem of excess nitrogen. However, it may be computed that 750 kg
of nitrogen and 50 kg of phosphorus could produce 7500 kg of algal cells, or about
2.3 mg/X of volatile suspended solids in the 2700 ac-ft of water impounded when the
water surface equaled 150 acres. This is in excess of the observed average values
of VSS in the impounded water, i.e., 2.25 mg/,0 in 1969-70 and 1.3 mg/,0 in 1970-71.
When it is considered that the phosphorus in the influent reclaimed water during
the two periods of study averaged 0.126 mg/0 and 0.086 mg/£, respectively, (Table
U), and that this phosphorus was likewise available to produce algal cells, it is
evident that the observed VSS concentration did not account for all the available
phosphorus in any event. This observation, however, does not take into account the
cycle of growth and degradation, precipitation of dead cells, etc., that character-
izes biological phenomena In the aquatic food chain.
The important fact is that the disparity between nitrogen and phosphorus inputs to
Indian Creek Reservoir, as well as between the N and P unaccounted for in Table 5,
indicates that an important fraction of the nitrogen did not leave the system in
combination with phosphorus.
In order to explain the reduction in ammonia in the reservoir evident in Figure 19
and the nitrogen unaccounted for in Table 6, samples of the benthic sludge were
taken at Stations 1 and 3 (Figure 2) and analyzed for nutrient content. The results,
reported in Table 6, show that in October 197° nitrogen in the accumulated sludge
averaged 2.65 mg/g for the two stations. This represents about a 2-year accumulation
of sludge, which for purpose of the calculations reported in Table 7 is assumed to
be representative of the two-year period of study even though the time spans are
not identical.
Table 7 represents an estimate of the nutrient balance for the reservoir over the
two years of study. In preparing this estimate several assumptions and assignments
were necessary:
1. All volatile suspended solids In the reservoir were assigned to algal cells
having an N/P ratio of 15:1.
2. Macro aquatic plants were assumed to be distributed throughout the reservoir
water mass in the same profusion as that reported in a following section (Biological
Observations).
-------
VI
o
TABLE 6
BEKTHIC AMD SOIL SAMPLE ANALYSIS AT INDIAN CREEK RESERVOIR
Date
Sept
1969
Oct Ik
1970
Source
Soil
(Composite)
Benthic
Benthic
Location
20 locations
a~bove water
line of
reservoir
Station 1
Station 3
Nitrogen as N
Organic
mg/g
0.58
2.96
2.32
NH3
mg/g
0.029
0.0
0.0
W2
mg/g
-
0.0
0.0
W3
mg/g
0.36
0.014
0.018
Total
mg/g
-
2.97
2.3^
Phosphorus as P
Available
mg/g
0.01
0.04
0.05
Total
mg/g
-
0.209
0.908
Total
Carbon
%
1.13
-
-
-------
3. Fish taken from the reservoir by migratory waterfowl were assumed to be equal
in number to those caught toy fishermen. The remainder of the fish planted in the
reservoir were assumed to be present in the impounded water and to be of the same
average weight as those caught by fishermen.
4. Phosphate in the available form in the original soil was assigned to the
benthic sludge along with the phosphate in water lost by percolation, plus sufficient
organic matter to bring the phosphorus budget of the reservoir into balance.
TABLE 7
ESTIMATED NUTRIENT BALANCE
April 1969 through March 1971
Source
Volatile Suspended Solids
Vascular Plants
Fish Life
Benthic Deposits
An w/o Percolation Loss
Percolation of NOa + NOs
Imbalance
+
-
-
-
-
+
-
Available
Phosphorus
kg
65
7
150
1+33
655
—
0
Total
Nitrogen
kg
975
100
900
22,900
102, 299
1A,337
+63,087
Although the actual relationship of origin and destination of any individual unit
of phosphorus is not reflected in Table 7> the relationship is of no consequence if
the location of various fractions of the total available phosphorus in the system
is correct.
The item in Table 7 least subject to checking is "Benthic Deposits." No survey of
the areal extent of the benthic sludge blanket was attempted. However, its existence
was readily verified by soundings in deep water but it was not characteristic of the
shallows except in the most southerly bays of the reservoir. Soundings at sampling
stations and at random points in the reservoir indicated a depth of sludge of about
2.5 cm was characteristic. Assuming 2.5 cm as an average depth of a sludge having
a specific gravity of 1.2 and the nutrient characteristics shown in Table 6, it was
calculated that 433 kg of phosphorus (Table 7) would represent an area of 71 acres.
Although such an estimate is at best rough, it is not implausible and hence supports
the general conclusion that the estimates in Table 7 are reasonable ones.
Nitrogen values shown in Table 7 were obtained by the same approach used in estab-
lishing phosphorus values. Additional assumptions were that the nitrogen concentra-
tion shown for benthic sludge in Table 6 prevailed in 71 acres of sludge 2.5 cm deep;
and that the soluble oxidized nitrogen initially present in percolating water left
the reservoir with that water. On this basis it develops that some 63,000 + kg of
nitrogen, or k& percent of the identified influent nitrogen was lost from Indian
Creek Reservoir during the two years of study. Such a loss may have involved a
combination of two phenomena; gas, resulting from denitrification; and soluble
nitrogen resulting from nitrification moving out with percolating water. Because
nitrification might be expected to occur at the interface between sludge and the
overlying impounded water, whereas denitrification should occur at lower depths in
the sludge where oxygen is deficient, gasification would seem to be the most likely
occurrence. In such case the 1^,357 kg loss of nitrogen assigned to "Percolation"
in Table 7 may be a gross overestimate and the nitrogen lost as gas might have been
appreciably more than U8 percent of the influent nitrogen.
51
-------
To discover whether denitrification was indeed a major factor in nitrogen loss from
Indian Creek Reservoir, microbiological assays were made of the benthic sludge.
The presence of both denitrifying and nitrifying bacterial in large numbers confirmed
that such an imbalance as predicted by Table 7 is reasonable. Further consideration
of the role of denitrification in the limnology of Indian Creek Reservoir is presented
in the following section on biological observations.
BIOLOGICAL OBSERVATIONS
Scope of Observations
Biological data collected on Indian Creek Reservoir range from general and specific
observations of an environmental nature made in the field, to detailed scientific
analyses made in the laboratory. Included in the first category are such aspects
as fish and wildlife of the reservoir and ijjimediate area, qualitative observations
of algae and rooted plants in the reservoir, and seasonal changes in the biota.
The more scientific examinations include bioassays of the growth stimulating potential
of influent, impounded, and discharged waters of the reservoirs, by methods outlined
in Section IVj benthic invertebrate surveys in October 1969 and 1970] and plankton
analyses in April 1970 and June 1971. Basically, the bioassays serve, within the
limits of existing methodology and project budget, to assess the eutrophication
potential of water reclaimed from domestic sewage [^,5] hy the most advanced of cur-
rently developing technology. The less intensive program of field and biological
examinations serve as checks on the validity of any conclusions which might logically
be derived from chemical analyses and bioassays of the water.
General Environmental Observations
As noted in Section III, Indian Creek Reservoir is located in relatively open country
with pinon pine and scrub brush on the east and north. Near the south end, but some
hundreds of feet from the shore line there are larger pines. These occur in a sparse
stand at the southwest, with a fairly dense growth on the west at the saddle dam and
Stevens Lake. Stevens Lake is shallow and contains a heavy growth of aquatic plants,
primarily Myriophyllum sp. which apparently have been transplanted into Indian Creek
Reservoir by the wildfowl which frequent the area.
Trout were successfully introduced into the reservoir in August 1969. Soon there-
after grebes were observed on the water. A wildfowl count on one occasion in late
September revealed the presence of more than 10 grebes and a similar number of coot;
12 ducks; a seagull; and a flock of sandpiper. Other wildlife present in the area
included frogs and snakes; and some 50 Brewer blackbirds were resident in the area.
On October 2k, 1969, 50 ducks were present and in mid-November the duck population
was estimated at 150. By late November all ducks had disappeared and no wildlife
was in evidence during the next two months. Deer were numerous in the area by mid-
February and by mid-March ducks had returned, kO being counted on the March 18, 1970
sampling date. Fish netted in March were 11 inches in length, well fed, and weighed
from 0.66 to 0.75 pounds each. On April 23, 1970 5 deer and two coyotes were observed
in the area. Ducks were present on both Stevens Lake and Indian Creek Reservoir.
Aquatic plants in the lake and muddied water and snail shell fragments gave evidence
that ducks were feeding in the shallows.
Gross observations were made of the insect, plant, and plankton life in the reservoir
on weekly sampling dates. Throughout the summer and fall of 1969 twigs and stones
in the shallow waters were covered with attached filamentous algae (Mougeotia).
This disappeared during the winter and was nowhere in evidence on April 2J, 1970.
However, at that time the early spring cold water alga, Ulothrix, was in evidence
and growing in profusion in Indian Creek just below the outlet to the reservoir.
In July 1969 midges (Diptera) were observed in flight and resting on the surface of
shallow water. Daphnia were found at all sampling stations in the reservoir and
were-observed to decrease with depth, the density (number per liter) varying directly
with dissolved oxygen concentration. In late July a profuse growth of filamentous
green algae (Draparnaldia) was present on the buoy and anchor rope at Station 1
-------
(Figure 2, Section IV). On September 10, 1969 this same alga appeared on the buoy
anchor rope at Station 3, extending down to depth of 6 meters. At Station 1 the
filaments were less noticeable. On September 15, Daphnia were present in all water
samples taken at all three sampling stations. Rooted aquatic plants, predominantly
Potamogeton, were found in profusion off the point of land between the main and saddle
dams.Eel grass and other aquatic plants were present in the shallow south bays of
the reservoir. Filamentous green algae Prasiola appeared, floating on the water
surface in small clumps. Ten days later it was still present. In early December
Indian Creek near the reservoir outlet was exceedingly green. In March 1970 the
reservoir was likewise green in appearance. On April 23, 1970 green masses of algae
in Indian Creek below the reservoir were observed to be, as previously noted a profuse
growth of Ulothrix.
Numerous adult chironomids were present on the water surface, and floating clumps of
algae were observed near the shore in April 1970. Early in May floating clumps of
algae were observed over the entire surface of the reservoir. In June about 25 water-
fowl were observed on the water and a few cattle were present on the drainage area.
In July and August 1970, as water was released for irrigation, the water level in the
reservoir dropped significantly, revealing a considerable amount of aquatic plants
at the southern end of the reservoir and a deposit of CaCO^ on the rock face of the
dam at the north end of the reservoir.
With the opening of fishing season in May 1970 fishermen appeared in large numbers at
Indian Creek Reservoir, but by September the fishing pressure was notably decreased.
At -unat time flying insects (chironomids) were numerous in the vicinity of the
reservoir and Daphnia were plentiful in the impounded water. Approximately 200 coots
were observed on the reservoir in October 1970- These apparently remained until
about the middle of November. In November deer tracks were plentiful along the shore
and deer hunters were in the area. Ice was first observed on the reservoir surface
on December 15 and by January 6, 1971 a 7-inch ice cover was on the reservoir. By
the end of January the ice cover had decreased to about one inch and covered only
about one-half of the reservoir surface.
On both the February sampling dates (1971) an extremely green cast was observed over
the entire reservoir, indicating a marked increase in phytoplankton. The smallest
Secchi disk readings (2.6 to 6.0 feet) were obtained in February, March, and April
1971 when this green color was most in evidence. Such a "phytoplankton bloom" like-
wise coincided with diminished clarity of the water identified by the Secchi disk
during February to April of the preceding year (1970).
Coots were seen briefly in March 1971 and ducks and other waterfowl became numerous
in April and May. In April chironomids were again observed flying near the shores
of the reservoir.
Apparently within the brief span of existence of Indian Creek Reservoir several
annual cycles have been established which involve and effect the limnology of the
reservoir. The annual spring phytoplankton bloom evidently starts in February after
the spring turnover when the surface water temperature warms up to above ^°C. This
is followed in April and May by a bloom of Daphnia which harvest the algae and cause
a marked increase in the clarity of the water. Migratory flocks of coots and ducks
appear in fall and spring and these birds, as well as resident grebes, blackbirds,
and swallows, may have a significant effect on increasing plant and animal species
new to the reservoir as well as adding readily available nutrients which might
increase plant growth in shallow shore line areas. Another limited source of such
nutrients is the increased numbers of domestic cattle and wild deer which frequent
the drainage area because of the availability of water.
Survey of Benthic Organisms
In October 1969 and again in October 1970, surveys of benthic invertebrates were
made at Indian Creek Reservoir by Mr. W. Arthur Noble of the EPA in cooperation
with the project staff. Results of these surveys are presented in detail in Table
16, Appendix.
53
-------
Samples of bottom sediments were obtained at Stations 1 to 7 (see Figure 2) in the
reservoir by means of an Ekman dredge vith 6-inch square javs. Shore line samples
at Station 8 were obtained from rocks taken from 2 to 2k inches below the water
surface at the main dam and scrubbed in a pail of water. This same technique was
used at Station 9 (reservoir outlet). Material was screened through a U. S. JO
sieve (0,589 mm openings). The screenings were placed in jars and preserved in
10 percent borate buffered formalin for subsequent examination.
At the time of the first sampling, October 8-9, 1969, the water depth in the
reservoir was ^8.75 feet and the deepest points had been under water continuously
for some 18 months. By October I1)-, 1970 (second sampling date) the reservoir had
been in operation an additional 12 months and the depth had decreased from a maximum
of 55.8 feet in the spring of 1970 to ^3.5 feet in October. Three factors must be
considered in evaluating reasons for changes in the composition of the benthic com-
munity: maturation of the reservoir; aeration of the impounded water; and inter-
actions between the organisms themselves, e.g., predation, competition, etc.
In .the 1969 samples only midges (chironomidae) were observed and about 90 percent
of the midge larvae were of three types; Chironomus, Procladius, and Glyptotendipes -
all of which have pigmented gills, making possible increased oxygen uptake in poorly
oxygenated waters. Apparently there was an oxygen deficiency in the benthos that
restricted the midge population to low oxygen resistant types. At the time of the
1970 sampling, aerators had been installed and had been in operation since June 23
of that year. This, as noted in a previous section, resulted in marked changes in
the oxygen resources of the reservoir.
By October 1970 water mites had become common in all samples and the three midge
genera observed in 1969 samples had declined to 66 percent of the total. The three
dominant groups in 1970 - Hydrarina (water mites), Chironomus sp., and Procladius
sp. — composed 91 percent of the total benthic community. Mites, however, being
predaceous may have been somewhat responsible for the decline in the chironomid
population.
As shown in Table 8, greater diversity was observed at Stations 1 to 5 in 1970 than
in 1969 although the total biomass had decreased from a mean of lt-28 to 280 organisms
per square foot.
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TABLE 8
SUMMARY OF BENTHIC ORGANISMS COLLECTED FROM
INDIAN CREEK RESERVOIR BY USE OF
ECKMAN DREDGE8
Station
Number
1
2
3
k
5
6
7
Mean
Number
of Dredge
Samples
Collected
(3)
(3)
(3)
(3)
(3)
(1)
(1)
Average Number
per Square Foot
1969
Ul2
588
528
6U8
268
361+
176
428
1970
588
160
392
260
160
120
— c
280
Diversity
1969
0.35
0.70
0.72
0.36
1.05
1.22
1.02
0.9^
1970
0.93
1.2
l.U
l.U
1-9
0.8
— c
1.5
Copepods and Cladocera not included in totals.
b z n n.
Diversity = -£-—. iogg — in which, n± = number of
1—*J-
individuals in a particular species and
N = the total number of individuals in
all species [17].
"No sample collected.
The presence of snails at Stations 4, 5> and 6, and mayflies at Stations k and 5>
indicated an overall improvement in the water environment from 1969 to 1970.
Aeration of the reservoir water was routine practice during the summer of 1970,
hence the greater diversity in 1970 was probably associated with oxygenation of the
low dissolved oxygen influent reclaimed water discharged into the reservoir near
Station 1. This postulate is supported by the observation that in 1969* before
aeration began diversity increased markedly in samples farther away from Station 1.
Although the diversity of the benthic organisms is lower than one would expect in a
mature reservoir, it is apparently increasing as the reservoir continues to stabilize.
However, the benthic standing crop is decreasing with time and thus the amount of
food available from the benthos to the fish population may be decreasing.
Samples collected off the submerged rocks near the dam (Station 8) and in the tail-
water (Station 9) just downstream from the reservoir outlet were not quantitatively
related to the area of collection. It is obvious from the data (Table l6, Appendix)
that the change in population diversity and density from I960 to 1970 paralleled
what occurred in the reservoir sediments. At Station 8 there were 15 groups of
organisms represented in 1970 as compared with but k in 1969. Similarly at Station
9, 2k groups were present in 1970 where only 10 were found the previous year. Thus
as a result of reservoir maturation and further introduction of viable species, the
diversity at these two stations apparently increased as it did in the reservoir
sediments.
55
-------
At Station 8 in 1969 the dominant form of organism in the low species diversity of
midge larvae was the low oxygen tolerant Glyptotendipes, which constituted 85 percent
of the individuals present. The results from Indian Creek (Station 9) likewise
showed a species diversity very low for a stream environment. "Dominance by midges,
absence of stoneflies and caddisflies, and the presence of only the pollution
tolerant mayfly nymph Siphonurus," Noble reported [^] "indicates enriched and
eutrophic conditions." The presence of a heavy growth of algae at Station 9 like-
wise gave the impression of a nutrient rich stream.
In 1970 the midges were greatly reduced in relative importance and organisms asso-
ciated with higher oxygen levels were more prominent at Station 8. This again may
be evidence of an effect of aeration of the reservoir, permitting the development
of a more diverse population of organisms. In any event the chironomids in 1970
were no longer as clearly an indicator of the condition of Indian Creek Reservoir
as was the case in 1969.
Winter eggs of the Cladocera, Daphnia, (ephippia) averaged 3,1^2 per square foot of
benthos in 1969 and but 1,9^5 per square foot in 1970. Both of these values indicate
that a large population of Daphnia had previously existed during the summer months.
This in turn means that a correspondingly high concentration of algae, bacteria, and
detritus on which Cladocera fed must have been present. The decrease in number of
eggs per square foot, however, does not necessarily indicate a loss of food supply
was the cause of reduced numbers of Daphnia. Predation by fish may have kept the
population down. Another year or two of observation of Indian Creek Reservoir may
well be the only way to determine whether its ability to support aquatic life is
decreasing or increasing with time.
Microscopic Examinations
Samples of water and benthic muds were taken on several of the sampling dates listed
in Table 1J, Appendix. These were preserved and later examined under the microscope
by Dr. James M. Lackey, Consulting Biologist, along with fresh samples taken in the
field on April 2J, 1970. Subsequently, on June 21, 1971 both fresh and preserved
samples were taken from the impounded water at 5 different depths at Stations 1, 2,
and 5 (Figure 2). These were examined by Mr. Albert Katko of the EPA. The organisms
observed by these microscopic surveys are summarized in Table 9.
From the survey of preserved samples reported in Table 9 it is evident that a varied
plankton population, indicating good productivity, had developed in Indian Creek
Reservoir by July 1969. Both green and blue-green algal forms were present, as were
diatoms and anchored plants. Protozoa were present at the benthic interface. The
presence of ammonia in the reservoir water would lead one to expect a diverse
plankton population. Similarly, the reduction in ammonia and carbon, discussed in
preceding sections, is in itself evidence of an active biota in the reservoir. These
findings support the conclusion that a maturing of the reservoir was a necessary
prelude to fish survival, not only to develop a food source but also to reduce
toxicity.
The results of microscopic examination of fresh samples and benthic muds reported in
Table 9 is more revealing of the productivity of the reservoir than are those of the
preserved samples. The variety and amount of planktonic biota shows that the
reservoir was a highly productive body of water. In fact the samples described in
the table as "Floating Floe - Lake Debris" shows a spectruiu or organisms typical of
impounded water, which indeed characterized the reservoir in April 1970, inasmuch
as no releases of water occurred after September 1969 and influent was diverted from
the reservoir when it reached full capacity in March 1970.
-------
TABLE 9
SUMMARY OF ORGANISMS OBSERVED El MICROSCOPIC SURVEYS OF INDIAN CREEK RESERVOIR
Preserved Samples
Sampling Date: July 29, 1969
Profuse f ilamentous material on buoy and anchor rope
at Sampling Station No. 1.
Chlorophyta
Draparnaldla
Sampling Date: September 10, 1969
Material on buoy anchor rope at Sampling Statics
No. 1. Heavy growth to six meters depth.
Bacterial slime (heavy growth)
Chlorophyta
Cosmarium (Desmid)
Capsalated alga (unidentified)
Diatoms
Navicula
Material on buoy anchor rope at Sampling Station No. J.
Chlorophyta
Draper na Id ia
Cosnariuai (Desmid)
Closterium (Desmid)
Cyanophyta
Merismopedia
Lyngbye
Chrysophyta (Diatoms)
Navicula (numerous)
Sampling Date: September 15, 1969
Algae attached to dead sedge at point between nain dam
and saddle dam.
Chlorophyta
Draparnalia (dominant)
Cyanophyta
Schizophrix (dominant)
Chrysophyta
Epiphytic algae
Floating green algae collected from lake surface near
east shore and main dam.
Chlorophyta
Prasiola
Benthic sample taken by dredge in 13-meter derti of
water at Sampling Station No. 1. (Subsurface"--.:;
mixed with sample; preservation not good.)
Chryscphyts
Navicula (Diatom)
Euglenophyta
Euglena sp.
Benthic sample by dredge at Sampling Station :io. J.
Water depth 9-5 m.
Chrysophyta
Navicula (Diatom)
Note: No other organism observed in sample.
Live vascular plant. Heavy growth in one to two ft of
water off point of land between main and saddle dams.
Potosageton
Algsl growth on live Eel Grass from one to two ft of
water off land point between main and saddle dams*
Chrysophyta
Network of Epiphytic algae
Chlorophyta
Chlorella (very numerous)
Cosmarium (Desmid)
Draparnaldia
Benthic sample by dredge at Sampling Station No. 2.
Water depth, 12 m. (Subsurface mud mixed vith
sample, preservation not good.)
Chrysophyta
Navicula (Diatom)
Pine pollen
Note: Very little to see in sample.
Benthic interface in 5-cm water depth at main dam
near Indian Creek channel.
Chlorophyta
Cosmarium (Desmid)
Chrysophyta
Navicula (Diatom)
Cyanophyta
Schizothrix
Clliate Protozoa
Colpoda
57
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TABLE 9 (Continued)
Sampling Date: September 15, 1969 (Continued)
Benthic interface in 5-cm vater depth at boat
launching ramp (east side of reservoir approximately
300 ft south of main dam).
Chlorophyta
Closterium (Desmid)
Chrysophyta
Navicula (Diatom) (very numerous)
Ciliate Protozoa
Fieuronema
Benthic interface in 5-cm water depth at south end of
small embayment on east shore of reservoir.
Chrysophyta
Navicula (Diatom) (numerous)
Cyanophyta
Merismopedia
Schlzothrix
Lyngbya
Chlorophyta
Cosmarium (Desmid)
Ciliate Protozoa
Colpoda
Sampling Dste: March 18, 1970
Surface tov with plankton net between main dam and
Sampling Station No. 2.
Daphnia
Rotifers
Harpacticoid Copepod
Worm
Outlet from Indian Creek Reservoir. Filamentous
bloom at time of sampling. Sample unpreserved.
Chlorophyta
(Filaments too decayed for positive species
Identification.)
Cosmarium (Desmid)
Ciliate Protozoa
Paramecium
Cyelidium
Jrsjh Samples
Sampling Date; Harch 18, 1970
Water Sample, Station No. 1 ( centr if uged )
Chlorophyta
Green slgal cells (unidentified)
CoscErium (Desmid)
Chrysophyta
Kavicula (Diatoms)
Meridion (Diatoms)
Protozoa
Zooflegellates
Water Sample, Station No. 3 (centrifuged)
Chlorophyta
Cosjnarium (Desmid)
Cryptosona d ida e
Cryptosonas
Chrysophyta
Haviiula (Diatom)
Euglenothyta
Euglena
Flagellate Protozoa
Zooflagellatee
Station Ko. 1, Bottom (centrifuged)
Chlorophyta
Chlorella
Flagellate Protozoa
Anlsonema ovale
Monas
Bodo
Zooflagellates
Ciliate Protozoa
Cyelidium
Miscellaneous
Cladocera ephlppie
Water Sample, Station Ho. 2 (centrifuged)
Chlorophyta
Chlamydomona s
Cosmarium (Desmid)
Chrysophyta
Navicula (Diatom)
Flagellate Protozoa
Zooflagellates
Miscellaneous
Hillea
Water Sample, South Bnbayment (centrifuged)
Chlorophyta
Chlamydomona s
Cosmarium (Desmid)
Chrysophyta
Navicula (Diatom)
Flagellate Protozoa
Zooflagellates
Ciliate Protozoa
Lionotus fasciola
Lake Plankton, Including Small Amount of Bottom
Sediment
Chlorophyta
Cosmarium (Desmid)
Mougeotia
Cryptomonadidae
Cryptomonas
Chrysophyta (Diatoms)
Navicula
Gomphonema
Synedra capitate
Asterlonella formosa
Flagellate Protozoa
Zooflagellates
58
-------
TABLE 9 (Continued)
Sampling Date:
March 18, 1970 (Continued)
Floating Floe - Lake Debris
Reservoir - Lake Debris
Chlorophyta
Cosmarium (Desmid)
Closterium
Evastrum
Cryptomonadidae
Cryptomonas
Chrysophyta
Navicula (Diatom)
Cyanophyta
Oscillatoria
Schizothrix
Euglenophyta
Euglena
Flagellate Protozoa
Bodo
Chroomona s
Notoseknas apocamptus
Peranema
Ciliate Protozoa
Oxytricha
Cinetochilum
Aspidisca castata
Chilodonella
Stichotricha
Miscellaneous
Rotifer
Dipterous larvae
Chlorophyta
Cosmarium (Desmid) (vast amount)
Chlamydomona s
Ciliate Protozoa
Cyclidium
Oxytricha
Flagellate Protozoa
Notoselenas apocamptus
Zooflagellates (vast number)
Cryptomonas
Chroomona s
Chrysophyta
ifavicula (vast number)
Miscellaneous
Amoeba vespertilio
Rotifer
Growth on Buoy, Sampling Station No. 2
Floating Floe Opposite East Boat Launching Ramp
Chlorophyta
Cosmarium
Closterium
Chlamydomona s
Chlorella
Ulothrix
Cya nophyta
Oscillatoria
Lyngbya
Schizothrix
Chrysophyta (Diatom)
Navicula
Eunotia
Chryptomonadidae
Chryptomonas
Chlorophyta
Chlorella
Cosmarium (Desmid)
Closterium
Chlamydomona s
Chrysophyta
Nsvicula (Diatom)
Cyanophyta
Merisraopedia
Oscillatoria
Proteomyxa
Nuclearia
Ciliate Protozoa
Oxytricha
Vorticalla
Flagellate Protozoa
Hotoselenus apocamptus
Chryptomonadidae
Chryptomona s
59
-------
TABLE 9 (Continued)
Sampling Date: March 18, 1970 (Continued)
Growth on Concrete Bottom of Outlet from Reservoir
Chlorophyta
Cosmarium (Desmid)
Chlorella
Closterium
Euglenophyta
Petaljnonas
Euglena sp .
Euglena gracilis
Spenomonas teres
Anisonema ovale
Chrysophyta
Navicula (Diatom)
Cryptomonadidae
Cryptomonas
Mycetoza
Amoeba vespertillio
Ciliate Protozoa
Vorticella
Aspidisca costatus
Cyclidium
Flagellate Protozoa
Notoselenus
Chroomonss
Miscellaneous
Hematode
Chirinomid larvae
Carinita
Dens Mat of Algae in Runoff Ditch Below Dam
Chlorophyta
Ulothrix
Closterium
Cosmarium (Desnid)
Scene de smus
Cyanophyta
Merismopedia
Cryptononadidae
Cryptomonas
Euglenophyta
Euglena viridis
Ciliate Protozoa
Oxytricha
Cyclidium
Miscellaneous
Rotifer
Chironomld larvae
Growth on Dead Grass in Reservoir
Chlorophyta
Cosnarium (Desmid)
Closterium
Chlamydomona s
Chrysophyta
Eunotia
Navicula (Diatom).
Flagellate Protozoa
Notoselenus
Chroomonas
Ciliate Protozoa
Oxytricha
Vorticella
Benthic Detritus Samples
Sampling Date: October lU, 1970
Rooted Aquatics
Myr iophyllum sp.
Liverwort
Hiella
Algae
Cyanophyta
Oscillator ia
AgmenellUBi
Phormidium
Chlorophyta
Ulothrix
Closterium
Cosmarium
Euglena
Volvox
Chrysophyta
Navicula
Achnanthes
Surirella
Hydrurus
60
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TABLE 9 (Continued)
Preserved Samples
Sampling Date: June 21, 1971
Station No. 1 0.5 m
Chlorophyta
Chlamydomona s
Gleacystis
Chrysophyta
Ochromonas
Achnanthes
26k
66
2838
33
Total per ml 3201
Station No. 1 7m
Chlorophy-ta
Chlamydomona s
Gleocystis
Schroderia
Chrysophyta
Ochromonas
99
99
33
261
Total per ml, 792
Station No. 1 14m
Chlorophyta
Chlamydomona s
99
Total per ml 99
Station No. 3 0.5 m
Chlorophyta
Chlamydomona s
Gleocystis
Schroderia
Chrysophyta
Ochromonas
Achnanthes
858
33
99
5247
33
Total per nU 6270
Station No. 3 5 m
Chlorophyta
Gleocystis
Schroderia
Chrysophyta
Ochromonas
165
33
1617
Total per mJ IBl5
Station No. 3 10 m
Chlorophyta
Gleocystis
Chrysophyta
Achnanthes
Cymbella
Nitzsehia
132
33
33
66
Total per ml S&k
Station No. 2 0.5 m
Chlorophyta
Chlamydomona s
Gleocystis
Schroderia
Chrysophyta
Ochromonas
Total per E,"
361
165
33
2937
31*96
Station No. 2 6m
Chlorophyta
Chlamydomona s
Gleocystis
Chrysophyta
Ochromona s
Total per ~t
99
99
2244
2442
Station No. 2 12 n
Chlorophyta
Gleocystis
Chrysophyta
Ochroiaonas
Total per s.i
99
165
254"
. Filamentous Material st Xtlet
Chlorophyta
Chlamydomona s
Closteriua
Cosmarium*
Dictyosphaeriu.1
Oedogonium*
Scenedesmus
Stigeocloniun*
Chrysophyta
Gomphonema
Cyanophyta
Aggmenellum
Stigonema*
Phormidium
Predominant type of organism.
61
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As noted in a preceding section entitled "Survey of Benthic Organisms" bottom samples
were taken on October 1^, 1970, from which benthic invertebrates were separated by
use of a U. S. No. JO sieve. Organic debris retained along with these invertebrates
was examined under the microscope by Mr. Albert Katko. As reported in Table 9,
Myriophyllum sp. was present and the Liverwort, Riella sp. was common at all sampling
stations. The most abundant forms were mats of the blue-green alga, Oscillatoria;
the filamentous alga, Ulothrix; and the diatom Navicula. Other forms were typically
benthic algae which were found in most samples at most times of the year.
On June 21, 1971, water samples were collected at surface, mid-depth, and bottom water
at Stations 1, 2, and 3. At the same time filamentous material was collected from
rocks in the stream at the outlet of the reservoir. As may be seen from Table 9, very
little diversity was observed in the reservoir samples and the diatoms observed were
typical of benthic rather than planktonic types. Except for the flagellates
Ochromonas and Chlamydomonas, which were the dominant algae observed, the algal
population was primarily associated with benthic production. This was borne out by
the clarity of the water - 17-5 feet Secchi disk depth - observed on the sampling
date (June 21, 1971).
Ochromonas and Chlamydomonas can utilize organic sources of nutrition and such sources
would probably be benthic in origin because only a very low input of organic material
from the STPUD effluent occurs, e.g., BOD less than 2.0 mg/£ more than 50 percent of
the time (see Table 17, Appendix). The observation that most of the Ochromonas and
Chlamydomonas were concentrated in the top layer of the reservoir indicates that
light is probably the major energy source for their production.
The planktonic population was representative of unstable conditions in the reservoir.
This is probably a result of some of the cycles (i.e., phytoplankton to Daphnia to
phytoplankton) which occur in the reservoir. The grazing effect of Daphnia apparently
is restricting the development of a large phytoplankton community. This should be of
considerable importance in the prevention of severe algal bloom problems. However,
the development of mats of Oscillatoria, as observed in the October 1970 detritus
sample, may be of considerable long-term consequence. Such mats may presage the
development of severe blue-green blooms of a noxious type of algae.
Trout in Indian Creek Reservoir
The history of fish plantings in Indian Creek Reservoir reveals much information
concerning the maturing of the reservoir with time. During the summer of 1968 trout
were placed in test boxes in the reservoir water but failed to survive for longer
than 2k hours, some dying within 30 minutes. To test the reservoir environment
further, 2,080 rainbow trout fingerlings 3 to k inches long were planted in the
reservoir on October l6, 1968, some 6 months after filling of the reservoir began.
No mortality was observed during the fall months but by springtime no fish appar-
ently remained. Fish mortality was presumed to be due to a lack of dissolved oxygen
caused by prolonged heavy ice cover of the water surface during the winter of 1968-69,
although this presumption was not fully proven.
On August 8, 1969, 3,600 hybrid (rainbow and cutthroat) trout 1.7 inches in length
were planted in the reservoir. Three days later ^,^00 trout of the Hat Creek (Mono
County) Rainbow strain were planted. These were some ^.5 inches in length. An
overnight gill netting operation on October 1969 produced a catch of 130 of these
fish. By that time the small fingerlings had grown to 6 inches in length and the
second group averaged 8.9 inches long. Subsequently, in March 1970, a one-day gill
net setting yielded 18 fish most of which were 11 inches long, the smallest being
10 inches.
62
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On February 20, 26, and 27, 1970 a total of 31,000 rainbow trout of the Mt. Whitney
strain, k,$ to 6 inches long, were planted in the reservoir. Subsequent fish plants
in 1970 were: June 12, 20,000 fingerlings; July 2, 5,500 legally catchable trout;
August 17, 22,000 fingerlings. All these plantings were trout.
Obviously something occurred during the reservoir's development which made it
compatible to trout. Although the exact cause of mortality of fish in the 1968
tests is not known, some toxic factor was evidently present. Inasmuch as the
recommended limit for ammonia at normal outdoor values of pH is 2.5 mg/,0 for trout,
ammonia toxicity seems the most logical cause of fish mortality at that time, the
influent to the reservoir having an ammonia concentration of from 12 to 20 mg/,0.
The most important factor in fish survival must then be the phenomenon which
reduced the concentration of ammonia in the Impounded water from these high values
to values ranging from 2.5 to 7-0 mg/,0 in subsequent months. As previously noted,
dilution alone was not the cause of nitrogen reduction. Evidence presented in a
preceding section indicates that denitrification in the benthic sludge is the
factor. However, if ammonia toxicity was indeed the toxic factor, two conclusions
are supported by the experience with trout in Indian Creek Reservoir:
1. That the establishment of a balanced ecosystem in which ammonia toxicity was
not a problem was necessary before the water became a suitable environment for
trout.
2. Some trout, especially those of the species and strains introduced to Indian
Greek Reservoir, can thrive at concentrations of ammonia more than double the
recommended limit.
Of course, the factors involved in fish mortality and fish survival in Indian Creek
Reservoir are likely to be vastly more complex and subtle than the simple factor
of ammonia. Whatever the spectrum of such factors may be they seem to have been
stabilized, resulting in a good fishery. From the first plants of catchable trout
an estimated 32 Ibs/acre of trout (more than 5,000 pounds) were harvested during
the 1970 fishing season. The largest fish caught was 19 inches long and weighed
3.25 pounds. In February, April, and May 1971 plantings of small trout were 25,000,
30,000, and 20,000, respectively. The total weight of fish planted in 1971 was
3,090 pounds, compared with the total of 2,970 pounds from which the 5,000 pounds
were later harvested. Because the fishing season for 1971 extends until'September,
far beyond the closing date of the study herein reported, it is too early to
estimate what the 1971 catch may total. Nevertheless the most recent observations
of fish survival during the 1971 season indicates that the reservoir continues to
be a habitat conducive to rapid fish growth and good survival of planted trout
species. For example, a gill net setting of only 3 to k hours during the first
week of July 1971 yielded a catch of 120 fish.
Some indication of the changes which may be taking place in the reservoir may be
gained from an examination of the contents of the stomachs of trout. Such an
analysis reveals that either the food supply or the food preference of fish changed
during the period of study. In the spring of 1970 chironomids constituted most of
the stomach contents of trout, whereas Daphnia predominated in the spring of 1971,
and most recently (first week of July 1971) snails were the most" common food,
particularly in the larger fish. The observed decrease in the chironomid larval
population reported in the preceding section is quite probably the factor most
responsible for the decline of the importance of this organism in the diet of
trout. However, this decline in food may have had an effect on the trout population
as well.
On the opening weekend of trout season, fishing results were considerably poorer
in 1971 than in 1970. This may have been due to inclement weather, or to a reduc-
tion in the fish population. Also differences on the availability of feed and
cover in the reservoir may have caused changes in the catch of fish. Although the
catch rate from boats was nearly the same in 1970 and 1971, the shore fishermen
had very poor results in the latter year. Table 10 presents data on this point
supplied by the California Department of Fish and Game. Changes in shoreline
-------
conditions may have resulted from such factors as increased growth of aquatic plants,
thus increasing feed and cover for fish while physically interfering with the
fishermen.
As in the case of evidence drawn from benthic surveys of invertebrate organisms,
the results of fish catches during the period of study suggest that the reservoir
may be declining in capacity to support aquatic life. Such an indication, however,
must remain highly tentative until data from more years of observation either
confirm or deny its validity.
TABLE 10
SUMMARY OF CREEL CENSUS RESULTS FOR OPENING
WEEKEND OF FISHING SEASON AT INDIAN CREEK
RESERVOIR, 1970 AND 1971
Factor Observed
Number of anglers
Man-hours of fishing
Total of fish caught
Catch per hour
from shore
from boats
Catch per angler
from shore
from boats
1970
939
3382
1202
0.36
0.37
0.26
1.28
1.42
0.76
1971
606
2196
238
0.11
0.08
0.20
0.39
0.28
0.83
Aquatic Vascular Plants
At least six different aquatic plants are present in Indian Creek Reservoir in some
abundance. Five of these are tentatively identified as: Ceratophyllum (coontail),
Myriophyllum (milfoil), Elodea (waterweed), Salvinia (water fern), and Potamogeton
(pondweed). The sixth is an unidentified grass. In a survey made by the project
staff in August 1970, Myriophyllum was found to be the most abundant plant. The
estimated standing crop of all species in the entire reservoir at that time was
approximately 5560 pounds dry weight of plant material. Of this total, Myriophyllum
comprised about 70 percent. Plants of the different species were present as
discrete clumps, generally circular in shape and separated from other clumps by
clear areas of sediment, Potamogeton was found only in the deeper waters.
The estimates reported in Table 11 for August 1970 were obtained by first determining
by observation the fraction of the total reservoir where plants were abundant.
This fraction was then studied in detail at low water to determine the frequency
of occurrence of each type of plant and the area of each individual clump, thus
obtaining an estimate of the percent areal occurrence. (Column 2). The weight of
randomly selected clumps were then measured by sampling and determining in the
laboratory the dry weight of sample per square foot of area sampled.
-------
TABLE 11
ESTIMATE OF VASCULAR AQUATIC PLANT STANDING CROP
IN INDIAN CREEK RESERVOIR, 1970
Plant
Myriophyllum
Ceratophyllum
Salvinia
Grass
Potamogeton
jElodea
Total
Area
Covered
(% of area
studied)
U.8
0.6
0.3
1.2
0.1
(assumed)
0.1
1%
Dry Weight
(Ib per sq ft of
area covered)
0.16
0.27
0.28
0.057
o.Uo
0.1^
Total It in
Reservoir
3800
7^0
410
31<-o
200
70
5560
Figure 23 shows the results of a field experiment conducted on August 19, 1971.
To obtain the data summarized in Figure 23 A, samples were collected at noontime
along a transect at the southern end of the reservoir in an area where the plant
growth was generally profuse. Sampling points were selected in open water where
no plants were growing. In all cases the DO at the surface was greater near the
shore than at the middle of the transect, about 900 feet offshore, where the water
was deepest. As shown in the figure the highest observed DO was 8.2 mg/.g at a
distance of 12 feet from the shore. Thereafter it decreased linearly until at
96 feet offshore it was but 5.7 mg/^ or essentialy the same as the 5-3 mg/,0 at
the middle of the transect. Thus it is evident that a substantial area of the
surface water of the reservoir was being oxygenated by the vascular plants under-
lying it.
More dramatic evidence of this effect. is seen in Figure 23 B. Here the dissolved
oxygen concentration was measured with time in the center of a large patch of
Fotamogeton sp. in a water depth of .k feet. Between sunrise and noon the DO
concentration rose from a concentration close to that found at the center of the
transect to a value greater than 11 mg/.0 by noon. Almost immediately thereafter
a wind came up, mixing the water and causing a precipitous decline in the dissolved
oxygen at the point of sampling. ..,''.
From the results of the field study of vascular plants at Indian Creek Reservoir
it is evident that such plants affected the DO resource of the reservoir to a
marked degree. Thus they are quite Important in the chemical and biological
aspects of the water quality, although as shown in Table 7 their importance in
the nutrient balance is minimal.
Microbiological Studies of ^
In the summers of 1970 and 1971 experiments were performed to determine the effects
of microbial activity on nitrogen metabolism in Indian Creek Reservoir. The
purpose of these experiments was to answer more precisely the question of what
happens to the influent ammonia nitrogen (NHa-N) once it enters the reservoir
ecosystem. However, due to constraints of time and personnel, these experiments
represent only single measurements of conditions existing at a particular time
-------
10
o>
UJ
8 5
o
o
£
Q
Concentration at Center of Basin
I
24 48 72
DISTANCE FROM SHORE, feet
96
15
^
E
10
Sunrise. 6 AM
12 Noon
Wind Mixing
B
Concentration at Center
of Basin
Samples collected over
a patch of Potamogeton sp.
i i i
_L
-I 0 +1 +5 +10
HOURS AFTER SUNRISE
FIGURE 23. DISSOLVED OXYGEN INCREASE BY VASCULAR
PLANTS
66
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of year when the metabolic rates are expected to be the greatest. Thus the results
of the experiments provide a basis for estimates only of the active conditions in
the reservoir.
From a comparison of the concentrations of oxidized forms of nitrogen observed in
the influent reclaimed water and the impounded water (see Table 13, Appendix; and
Figure 20) it was apparent that some of the influent ammonia was being metabolized
to nitrates by nitrifying bacteria in the reservoir waters. A considerably greater
quantity of ammonia, however, was (see Table 7) leaving the system in a manner not
readily identified. To explore the question of nitrogen metabolism as a factor in
this apparent loss of nitrogen from the reservoir system, measurements of the rate
of nitrification were made on August 19, 1970.
Samples were collected at 1:00 p.m. from Station 1 (Figure 2) at 5 different depths
below the water surface and analyzed for dissolved oxygen as well as for nitrites
and nitrates (N03-N, and NOa-U). Within three to four hours after collection, the
samples were placed in the dark at a 'temperature of l6.5°C and vigorously aerated.
Further measurements of NOs-N, NOa-N, and NH3-N were made at daily intervals and
the nitrification rates were calculated by dividing the difference between the
initial and 5-day NOa-W concentration by the period of incubation (5 days).
The results of the experiment, summarized in Figure 24, show that nitrification
apparently does not become measurable by the procedure used except in the impounded
water below the thermocline, i.e., in the hypolimnion. In this region it increased
sharply with depth to a certain point; then decreased rapidly, probably because the
dissolved oxygen decreased to a level below which it became limiting to nitrifying
bacterial activity. The thermocline apparently provided a density barrier to the
distribution of the nitrification activity throughout the water column. At other
times of the year when density differences are insufficient to maintain a stratifi-
cation, and dissolved oxygen is in abundant supply, it might be expected that
nitrification would be more generally distributed throughout the water mass and
would also proceed at a greater rate for the reservoir as a whole.
RATE OF NITRATE PRODUCTION,/* N//-doy TEMP, «C
0 250 500 18 19 20 21 22
12 3 456 7 8
DISSOLVED OXYGEN CONCENTRATION, mg//
FIGURE 24. VARIATION IN NITRIFICATION RATE, DISSOLVED
OXYGEN AND TEMPERATURE WITH DEPTH,
MDIAN CREEK RESERVOIR, AUGUST 1970
-------
The overall nitrate production for the water column at Station 1, assuming a column
one meter square and 13 meters high, was about 1.5 g N/m2/day. The specific rate
NOa-N produced/pg NH3-N available) per day for water below the thermocline was
about 0. 1 days"1.
An uneven distribution of nitrification activity throughout the hypollmnion, because
of lack of uniformity of water depth and the variation observed in nitrification
rate with depth, precludes and accurate assessment of the overall rate for the
entire reservoir. A crude estimate can, however, be obtained from the experimental
data of August 1970. At that time the thermocline was at about 6 meters (19-7 ft),
hence a relatively small proportion of the reservoir volume was involved in the
nitrification activity observed. Estimating that the mean rate of nitrification
was 200 ng N/f/day below the thermocline, and that nitrification took place within
a volume of 320,8*10 m3 (260 acre-ft), (the volume below the thermocline) the overall
rate of nitrification for the whole reservoir was 6k kg N/day. This compares with
an average daily input of 170 kg NHa-N/day for the 2-year period of study. On this
basis it follows that about 35 -ko percent of the input ammonia was nitrified,
resulting in a concentration of 7-8 rag NOs-N/£. Although this is two or three times
the ammonia concentration observed in the reservoir the estimate is not too un-
reasonable, particularly when one considers the annual fluctuation in volume, dis-
solved oxygen, and temperature as well as all the biological reactions which would
serve to remove nitrogen.
The biological reaction responsible for removing nitrogen which appears to be most
important in Indian Creek Reservoir is bacterial denitrif ication. An estimate of
denitrif ication rates was made as a part of the August 1970 study. A water sample
was collected from Station 1 and immediately processed by placing aliquots in
individual BOD bottles, adding approximately 0.2 g of sodium sulfite to remove
oxygen, and inoculating all but the controls with 5 cc of a slurry of benthic sludge
taken from the top 1-2 cm of sludge at the interface in about 2 feet of water. The
BOD bottles were then sealed, placed in the dark, and allowed to incubate at l6.5°C.
Initial and daily measurements of NOa-N, N02-N, and HHa-N were made to determine
the net loss of ammonia in controls and in test samples.
Calculated rates of denitrif ication were 1JJ jog N/^/day for the controls and l6l
ug N/i/day for the sediment inoculated samples. Expressed in terms of the volume
of benthic sludge in the system the denitrif ication rate was 16 pg N/cc sediment/day.
For 1J5 acres of sediment 1.32 cm deep (equivalent to 71 acres at 2.5 cm depth used
in previously presented estimates) one obtains a value for total benthic sediment
of 7200 m3. Thus 120 kg N/day would be lost from the reservoir by denitrif ication
through the effect of bacterial activity in the benthic sludge.
If the daily input of NHa-N averages 170 kg/day and the denitrification loss is
120 kg/day, it follows that this 120 kg must first be nitrified and incorporated
in the sludge so that denitrification could release it to the atmosphere as gaseous
material. The remainder of the initial NH3-N input to the reservoir (50 kg/day)
would remain in the impounded water and lead to a concentration of 6 mg/^ in that
water. Such a value is not too different from the observed k to 7 mg/,0 reported in
Table 13, Appendix.
If the denitrification rate of 120 kg N/day is applied to the 2 years over which
the nutrient budget was taken, the nitrogen loss by denitrification would approximate
85,000 kg U. The estimated nutrient budget for nitrogen (Table 7) showed a deficit
ascribed to denitrification of some 63,000 kg for the period of study, plus any
fraction of an additional 1^,337 kg of nitrogen carried as oxidized nitrogen in
percolating water which may have been denitrified in the benthic zone. Thus the
values for nitrogen lost by denitrification are not unreasonably far apart con-
sidering the assumptions involved in both.
Nitrif ication-denitrif ication rate estimates are summarized in Table 12, along
with the input of NHa-N computed on both a daily basis and the two-year total.
For purposes of comparison, estimates are also made of the rates which would be
necessary to produce the average concentrations of NOs-N + NOa-N and NHa-N actually
observed in the reservoir over the two years of study (see Table 5).
68
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TABLE 12
ESTIMATES OF RATES OF AMMONIA OXIDATION AND OF DENITRIFICATION
OF NITRATES IN INDIAN CREEK RESERVOIR AS OF AUGUST 1970
(Values in terms of N)
Input of NH3-N by
Reclaimed Water
Daily
170 kg
2-year Total
12^,000 kg
Nitrification Rate
Daily
6k kg
120 kg*
2 -year Total
^7,000 kg
91,000 kg*
Denitrification Rate
Daily
120 kg
83 kg*
2-year Total
85,000 kg
61,000 kg*
Estimated from actual mean chemical concentrations over the two-year
period of study (data from Table 5).
Calculated Nitrification Rate
Calculated Denitrification Rate =
D (A - B)
"A C
D (A - B + E)
in which
A = input NH3-N concentration = 18,826
B = NHa-N concentration in reservoir = 3,62^
C = dilution' factor =0.7
D = kg input of NHa-N on daily or 2-year basis
E = NOa-W + NOa-N concentration in reservoir water = 3,121 |og/.0
Further confirmation of the importance of nitrification-denitrification in Indian -
Creek Reservoir was obtained by analysis of benthic sludge samples for bacteria
during July 1971.
This analysis, made under the direction of Dr. R. C. Cooper of the University of
California, revealed the presence of denitrifying bacteria in numbers characteristic
of a healthy denitrifying benthic sludge.
Bioassays
Bioassays of influent reclaimed water and impounded water at Indian Creek Reservoir
were made by the flask assay method described in Section IV. This method was
adopted because considerable experience in the technique and interpretation of the
test results had been acquired by the project staff during previous and concurrent
studies [5,8, 9, 1^] in the Lake Tahoe Basin and in Indian Creek Reservoir [k].
Moreover, the development of standard techniques by the EPA [20] and its contracting
groups had not yet produced a more acceptable alternate procedure.
As noted in Section IV, the test involves the use of a single species of test alga
(in this case Selena strum capricornutum). This allows the analysis of a large
number of samples in a limited space, yet provides a reasonable estimate of the
comparative biostlmulatory response of different samples.
From flask assays of Indian Creek Reservoir waters, undiluted and at various concen-
trations in filtered Lake Tahoe water, three measures of growth response were
computed: They are specific growth rate, £. ; cell concentration, X5; and cell mass
produced during five days of growth, SS5. These are likewise reported in Table 18,
Appendix. The value of £. was calculated by computer analysis as the maximum slope
of the growth curve identified by cell counts after 1, 3, and 5 days of incubation.
-------
X5 is the maximum number of cells attained at the end of a 5-day growth period,
evaluated as the average after replicate counts. 885 represents the suspended
solids measurement obtained after 5 days of growth.
As previously noted, and as evident in Table 13, Appendix, the influent reclaimed
water entering Indian Creek Reservoir was apparently so overwhelmingly phosphorus
limited that no biochemical changes during the period of impoundment came within
one order of magnitude of bringing N and P into biological balance in either the
impounded water or the discharged water during the period of study. Quite likely,
as discussed in a preceding section, biological activity in the benthos utilizing
and recycling phosphorus from sediments and the soil, together with denitrification
and dilution, accomplished the observed loss and conversion of nitrogen compounds
necessary to make the reservoir water tenable to trout.
The results of bioassays of undiluted samples of reclaimed water (III), and impounded
water (C), are shown in Figure 25- These show a considerable variation in values
of £i-fo. For Impounded water, a comparison of the chemical data summarized in
Figures 3 through 22, reveals very little coincidence of peaks in the water quality
curves and those in the j^ curves of Figure 25. A general trend, however, is for
^ to increase during the winter season when the reservoir temperature and incident
solar energy are low, and algal growth is at a minimum; and to decrease during the
warmer months when conditions for algal growth are favorable. A reciprocal of this
general trend can be seen in the variation in water temperature, suspended solids,
and volatile suspended solids; Figures k, J, and 8, respectively. The foregoing
trend is especially apparent in the almost complete lack of growth response in
impounded water during the February-March 1971 period. At that time a sharp increase
in both the suspended solids and volatile suspended solids values occurred. The
explanation of this phenomenon again is that as the organic growth which appears
as suspended solids increases, the nutrients are correspondingly reduced until one
or more become limiting. A physical factor such as temperature or solar energy,
or a toxic substance, could also limit growth. Thus a sample collected during this
time period would already be deficient in some essential nutrient and hence would
not produce further algal growth in the flask assays even though other nutrients
might be present or in excess.
Although phosphate was assumed to be limiting to growth in impounded water, there
is little identifiable relationship between £b in Figure 25 and phosphate concen-
tration in Figure l6. This might suggest that some other element, possibly a minor
nutrient or biostimulant, was the limiting factor. However, when aliquots of
phosphate solution were added to the flask assays (data not herein reproduced) algal
growth was clearly promoted. Therefore, considering the large N/P ratio, concen-
tration of individual chemicals, and the observed increase in algal growth with
phosphate additions, it seems probable that the standing crop of algae in the
reservoir incorporates the available phosphorus in cell material at such a rate as
to render the water incapable of supporting much further growth in the flask assays.
In this case jj^ may be said to reveal the efficiency of utilization of phosphorus
in the reservoir rather than the true growth stimulating potential of the impounded
water.
The growth response (£•£>) of reclaimed water (Figure 25) shows little relationship
to that of the impounded water and is generally lower in value. Fluctuations did,
of course, occur throughout the period of study but because the water had just
emerged from the reclamation plant its variation in quality was a function of plant
performance rather than of the seasonal cycles of organic growth and decay to which
the^impounded water was subject. Thus it must be recognized that whereas the values
of jjfc for the impounded water were influenced by the quality of influent water and
surface runoff, as well as by pre-stripping of nutrients during seasonal cycles of
biological growth, the growth rates (j^) in reclaimed water were a function of its
basic chemical quality, which may have included toxic materials or been deficient
in trace elements.
70
-------
<<
1 1 1 1 1 1 1 1
i i I. I 1 1 1
Apr May June July Aug Sept OctN^ Dec I Jan FebMar Apr May Ju>e JulyAugSeptOctNo/DecJonFebMarAprMayJuneJuly
1969
1970
871
FIGURE 25. MAXIMUM SPECIFIC GROWTH RATE, JLL^ FOR UNDILUTED SAMPLES FROM THE INDIAN CREEK
RESERVOIR SYSTEM
-------
In view of the different factors influencing the growth rates in bioassays of
reclaimed water and impounded water, no especial relationship between the two
curves in Figure 25 is to be expected. However, the fact that impounded water
which is supporting some growth is still more capable of producing growth in the
flask assays than is the influent reclaimed water is a significant finding.
-------
SECTION VI
DISCUSSION AND EVALUATION OF RESULTS
Evaluation of specific findings of environmental, chemical, and biological
observations of Indian Creek Reservoir is included in Section V as a part of the
interpretation and discussion of the individual subjects therein presented.
Conclusions are drawn in that section as deemed appropriate by the authors. These
are summarized and extended in Section I, and recommendations are summarized in
Section II. Therefore it seems appropriate to consider, in this section what the
Indian Creek Reservoir study has thus far shown concerning the reclamation of
water from domestic wastes for recreational use and its import in the context of
eutrophication of surface waters, as well as the changes observed with time in the
impounded water itself.
In evaluating the results of the study herein reported it must be borne in mind
that although Indian Creek Reservoir in 1970 and 1971 was providing recreational
opportunity in the form of sport fishing and development for contact sports is
contemplated, it was adapted rather than designed for such purpose. This is to
say that the processes to be applied to secondary waste water effluent at the
South Tahoe Public Utility District Plant were not originally selected with the
objective of producing a water quality ideally suited to the multiple beneficial
uses which are compatible in a wilderness. Instead they were the outgrowth of
concern on the part of water quality control officials for the consequences of
fertilizing surface waters with nutrients added by domestic use of water — nutrients
which are only stabilized and not removed by the best, or even perfect, sewage
treatment plants of the conventional type. Overriding even this national problem,
and the national objective of its solution, was the unique situation existing in
the Lake Tahoe Basin. Here it was deemed unacceptable, and on good evidence, to
discharge into Lake Tahoe even water which meets U. S. drinking water quality
standards, because in the matter of nutrients such standards exceed by some two
orders of magnitude the concentrations presently found in the lake.
The factors underlying process design were therefore based on a number of rational
concepts, not all of which were necessarily explicit in the decisions which
followed:
1. The time is at hand when in many circumstances conventional waste water
treatment processes must be extended to include nutrient removal or reduction.
2. Phosphorus is capable of triggering objectional algal growths when low
oxygen concentrations encourage algal species capable of utilizing nitrogen from
the atmosphere.
3. We know how to remove phosphorus, therefore in the course of "pollution
control" it should be removed as an act of faith if not of scientific necessity.
k. Nitrogen removal, although not immediately technologically developed, must
in the future likewise be applied to waste water effluents.
5. At the present state of technology and knowledge of the sensitivity of Lake
Tahoe, even the most highly treated waste water cannot be allowed to enter the
lake, either directly or indirectly. Therefore, export from the basin is a
practical necessity.
6. Given present aesthetic attitudes of people, exported effluents must be good
enough to be acceptable to the exporter himself under normal conditions, i.e.,
were it not for the unique quality of Lake Tahoe.
73
-------
7. Emerging standards of surface water quality must be met by any process of
vater reclamation.
8. A pioneering task of process development has to be undertaken if other concepts
of water quality are to be achieved.
Given objectives, constraints, and problems such as the foregoing, and the political
climate in which they must be resolved, the objectives of process design were
necessarily different than might have been the case had the creation of a recreations
reservoir been the water quality objective. This fact is extremely important in
understanding what has been observed at Indian Creek Reservoir; and in considering
what observations are required for the future.
The data herein presented show quite clearly that the reclaimed water delivered to
Indian Creek Reservoir during its first three years of operation were so low in
phosphorus as a result of purposeful phosphate removal by the South Tahoe Public
Utility District as apparently to be phosphate limited as an algal growth medium.
That is, it contained nitrogen in excess of phosphorus in some 10 times the N/P
ratio at which algae utilize these two nutrients, while at the same time being near
the concentration (0.10 rag/,0) of phosphorus at which growth is often thought to be
limited. Moreover, in its undiluted state it was toxic to both trout and the test
alga (Selenastrum) used in bioassays of its growth potential. For this reason it
was tentatively concluded early in the study that ammonia was the toxic factor.
Later it became apparent that in the impoundment this same water lost ammonia from
its initial 15 to 20 mg/,0 concentration to a level generally less than k mg/f,.
That the observed profound change in ammonia content was not due to simple dilution
was shown by a hydrological balance which revealed the reservoir input to be
approximately 70 percent reclaimed water from STPUD and JO percent surface runoff
and rainfall directly on the reservoir water surface. That it was not due to
nitrification alone was likewise evidenced by the failure of nitrates to reach any
sustained levels above about k mg/,0.
Loss of nitrogen from the reservoir by nitrification-denitrification was early
suspected as the cause of the observed nitrogen imbalance. From the evidence
developed in the study there is no doubt but-that nitrification in the hypolimnion
and denitrification in the benthic zone is the major mechanism. Analysis of the
benthic sludge in 1971 revealed the presence of denitrifying bacteria in numbers
characteristic of a healthy denitrifying sludge. Similarly, direct experiments
showed nitrification activity in the hypolimnion during the summer months sufficient
to account for the nitrogen lost by denitrification. Aeration of the reservoir by
mechanical means during 1970-71, however, gives reason to believe that the benthos
is the site of denitrification activity.
The amount of nitrogen lost from the reservoir was, as reported in Section V,
estimated by two approaches: a nitrogen balance based on hydrological and chemical
analyses, and microbiological studies of the reservoir. The amount of nitrogen
loss necessary to produce the levels of nitrogen observed in the weekly sampling
program cannot be determined with exactitude. The reasons are that the amount of
influent from the reservoir environment is unknown, and estimates can only approxi-
mate the amount of nitrogen tied up in biota and organic sludge in the reservoir
at any time. However, two estimates made from different approaches independently
place the total nitrogen loss during the two years of study herein reported in the
range of 61,000 to 8^,000 kg.
From the nitrogen studies it is concluded that nitrogen loss from the reservoir is
taking place; that nitrification-denitrification is the major mechanism, and that
the estimates of the amount lost are reasonable. Whether or not the reservoir has
reached a state of limnological stability is still unknown. The two-year curves
for ammonia and nitrates seem to indicate a tendency to increase with time. It is
too early to say whether this is a long-term trend. However, its implications are
sufficiently serious to suggest that this factor should be monitored for an
additional period of years.
-------
The efficiency of removal of phosphorus by the STPUD reclamation plant increased
•with time until during the 1970-71 year of study it was near the margin of detect-
ability in the reservoir water. No corresponding reduction in ammonia concentration
occurred, hence the H/P ratio increased drastically. Other sources of phosphorus
available to the biota in Indian Creek Reservoir must have compared favorably with
that of reclaimed water, otherwise it is difficult to explain the algal growth
which, in the early months of 1971* "was sufficient to give the reservoir a green
cast. Possible sources of phosphorus include the original soil on which the
reservoir was constructed, animal and plant wastes washed in from the small (1700-
acre) drainage area, and such allochthnous material as wind blown dust and pollens.
Although these sources might conceivably be considered minor, they could add to a
buildup in the benthic sludge which eventually becomes out of scale with the concen-
tration coming in the STPUD effluent.
The extent to which phosphate limitation is responsible for the apparent good quality
of Indian Creek Reservoir should be further studied in relation to sources of
phosphorus in order that the true value of phosphate removal as a waste water treat-
ment process may be determined. In the specific case of the Indian Creek Reservoir,
where the annual discharge equals the annual input and represents a large percentage
of the reservoir capacity, the buildup of phosphate by biological recycling may be
either more or less Important than in larger lakes, depending upon where the
phosphorus is in the system at the time of water releases. Further observations
of the buildup of benthic sludge with time will be necessary to clarify this point.
Biologically, Indian Creek Reservoir showed important changes over a two-year period.
From an initial situation in which it apparently would not support fish life, it
developed in 1970 into an excellent trout fishery. However, in 1971 the fish
production, as measured by early season catches, appeared to have declined. Gill
netting studies indicated that this might not be the case. In view of somewhat
contradictory, albeit fragmentary evidence, sucH as the nitrogen increase and the
question of fish population, it is clear that a number of factors should be
monitored for a longer period to determine whether the reservoir has reached
stability.
Evidence that with time the reservoir increased rather than decreased in biological
health is to be found in an increase in the diversity of benthic invertebrates
from 1969-70 to 1970-71. This diversity was the more convincing because of a
decline in the predominance of low oxygen tolerant species of chiromonads. The
extent to which this was the result of mechanical aeration of the water is uncertain
but it is well established [13] that such aeration of water will not preclude an
anaerobic zone in the underlying sludge or soil. This is further specifically
evidenced in Indian Creek Reservoir by denitrification activity traceable to the
benthic sludge.
Plankton in the impounded water, as well as the emergence of a normal cycle of algae
and grazers (Daphnia) in the Impounded water in 1971 likewise suggests an improving
limnological situation. Previously, in April 1970, a plankton survey of the
reservoir revealed a species distribution typical of impounded water.
Bioassays of impounded and reclaimed water were especially revealing of the
maturation of Indian Creek Reservoir. The cyclical nature of growth response, as
measured by the specific growth rate (^) of Selenastrum, showed clearly that the
growth potential of the impounded water increased during the cold season and
decreased during the warm season when the biota of the reservoir were utilizing
the nutrients. In contrast, no such cyclical response was clear in the reclaimed
water. This finding is logical and is particularly important because it differen-
tiates between the growth potential and the residual growth potential of a water.
This is to say that a bioassay of a waste water (filtered) may reveal its true algal
growth potential (within the limits of capability of the test), whereas in an
outdoor body of water it can only measure the residual potential in the water. In
wintertime more of the total potential of an impounded water might be in undecomposed
organic matter in the benthic sludge than in the water, whereas in the summer time
the reverse may be the case. But in any case a bioassay must be interpreted with
75
-------
caution when applied to a natural body of water. Conceivably, an extremely highly
eutrophied body of water could show little response because the test utilizes only
that fraction of the nutrients currently being recycled between decomposing and
growing biota. In contrast, a filtered waste water, or the reclaimed water influent
to Indian Creek Reservoir, harbors no nutrient sinks such as those in a lake or
reservoir. In this circumstance the lesser growth shown by reclaimed water than by
the impounded water indicates clearly that Indian Creek Reservoir as a limnological
entity is influenced by many factors not implicit in the mere quality of its
principal source of influent.
In an overall evaluation of Indian Creek Reservoir it might be said that the impound-
ment affords an unprecedented opportunity to observe, for practical as well as
scientific reasons, what may be expected from a ponding of water reclaimed from
domestic return flows. As noted in the opening paragraphs, no attempt was made
originally to design the waste water reclamation plant at South Tahoe to produce a
water of optimum quality for recreational purposes, if indeed such an optimum could
be defined. Eventually, however, the data from Indian Creek Reservoir should
indicate whether such an optimum process would be appreciably different than that
presently installed at STPUD. In the meantime it may be said that the STPUD plant
is a very efficient system for removing phosphorus, and Indian Creek Reservoir is
a good system for removing nitrogen. Whether or not the phosphorus removal is
presently unnecessarily effective, is the controlling factor, or is of little
consequence is an important practical and economic question. It cannot be answered
at Indian Creek Reservoir until the productivity of the reservoir has been observed
for another two or three seasons. If the water cycle is stabilized already, it may
be that nitrogen removal is not necessary in the treatment plant. If it is not,
it may mean that nitrogen removal is inadequate and, possibly, that phosphorus
removal is more than optimum.
-------
SECTION VII
ACKNOWLEDGMENTS
The Lake Tahoe Area Council (LTAC) acknowledges with sincere thanks the cooperation
and assistance of many agencies and individuals, both outside and within its own
staff, who contributed to the progress and activities of the study during the report
period.
Technical direction of the study was provided by the LTAC Board of Consultants
(P. H. McGauhey, G. A. Rohlich, and E. A. Pearson) as a part of its commitment to
the Lake Tahoe studies and in part as a donated public service.
Experimental work and data processing activities were led by Dr. D. B. Porcella,
Project Limnolegist, and Dr. Gordon L. Dugan, Project Engineer-Biologist. They
were assisted in the field and laboratory work by Messrs. Peter Cowan and
Jack Archambault and by Mrs. Nancy Deliantoni. Special studies and data evaluations
were made by Dr. James B. Lackey, Consulting Biologist, Melrose, Florida;
Dr. Arthur B. Hasler, University of Wisconsin; and E. J. Middlebrooks, University
of California (now of Utah State University). Budgetary control and accounting
were maintained by Mrs. Lois Williams and Mrs. Katharine Belyea of the LTAC staff.
To these individuals the Council is indebted for the success of the project. The
work of Messrs. P. H. McGauhey, D. B. Porcella, and G. L. Dugan in preparing the
report, and the assistance of Mr. Peter Bray and Mrs. June Smith in producing the
report manuscript, is gratefully acknowledged.
Agencies directly cooperating in the study included the California Department of
Water Resources, which provided geographical, hydrological, and geological data;
the South Tahoe Public Utility District, which provided data on the amount and
chemical nature of exported water; the Regional Office of the EPA and its Alameda
office, which made benthic invertebrate and plankton analyses for inclusion in the
report; the California Department of Fish and Game, which contributed facilities
as well as data and general information; and the University of California at
Berkeley and Davis, which contributed staff time, loaned equipment, and provided
expert counsel. Among the individuals from these agencies who were especially
helpful were Messrs. W. Arthur Noble and Albert Katko of the EPA; Messrs. Russel L.
Gulp, David Evans, Jerry Wilson, and Bernard Montbriand of the South Tahoe Public
Utility District; and Messrs. Philip Baker, Robert Tharatt, and Russel Wickwire,
of the California State Department of Fish and Game.
The support of the project by the Water Quality Office, Environmental Protection
Agency is acknowledged with sincere thanks, with especial thanks to Dr. Thomas E.
Maloney, who served as the Grant Project Officer, and to Mr. William C. Johnson,
who represented the Regional Office in advising the project staff.
77
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SECTION VIII
REFERENCES
1. McGauhey, P. H., ejt al., Comprehensive Study on Protection of Water Resources
of Lake Tahoe Basin, Lake Tahoe Area Council (1963).
2. "South Tahoe Public Utility District, Feasibility Report on Indian Creek
Reservoir," Glair A. Hill and Assoc., Consulting Engineers, Redding,
Calif. (April 1968).
3. "South Lake Tahoe Water Reclamation System," brochure South Tahoe Public
Utility District (undated - obtained in 1969).
^. McGauhey, P. H., e_t al., Eutrophication of Surface Waters — Indian Creek
Reservoir, LTAC, FWQA First Progress Report for Grant No. 16010 DNY
(May 1970).
5. McGauhey, P. H., ejt al., Eutrophication of Surface Waters — Lake Tahoe,
LTAC, FWQA, Final Report for Grant No. 16010 DSW (May 1971).
6. Standard Methods for the Examination of Water and Waste Water, 12th Ed.,
American Public Health Association, New York (1965).
7- Strickland, J. D. H., and T. R. Parsons, A Manual of Sea Water Analysis,
Bulletin No. 125, Fisheries Research Board of Canada, Ottawa (1965).
8. McGauhey, P. H., eb al., Eutrophication of Surface Waters - Lake Tahoe:
Bioassay of Nutrient Sources, LTAC, FWPCA Progress Report for Grant No.
WPD iJ-8-01 (Rl) (May 1968).
9. McGauhey, P. H., et al., Eutrophication of Surface Waters - Lake Tahoe:
Laboratory and Pilot Pond Studies, LTAC, FWPCA Second Progress Report
for Grant No. WPD 1*8-02 (May 1969).
10. Porcella, D. B., J. S. Kumagai, and E. J. Middlebrooks, "Biological Effects
on Sediment-Water Nutrient Interchange," American Society of Civil Engineers,
Sanitary Engineering Division (in press).
11. Maciolek, J. A., Limnological Organic Analyses by Quantitative Dichromate
Oxidation, Bureau of Sport Fisheries and Wildlife, Research Report 60,
Washington, D. C. (1962).
12. Skulberg, 0. M., "Algal Cultures as a Means to Assess the Fertilizing
Influence of Pollution, I," Advances in Water Pollution Research, p. 113,
Academic Press (1967).
13. McGauhey, P. H., and R. B. Krone, Soil Mantle as a Wastevater Treatment
System, Final Report, Berkeley, Sanit. Eng. Res. Lab. Report No. 67-11
(December 1967).
lU. McGauhey, P. H., et^ al., Eutrophication of Surface Waters — Lake Tahoe,
LTAC, FWQA Third Progress Report for Grant No. 16010 DSW (May 1970).
15. Eldridge, E. F., "Return Irrigation Water — Characteristics and Effects,"
U. S. PHS Region IX (May 1, 1960).
16. Bernstein, L., "Salt Tolerance of Plants," Agricultural Information Bulletin
283, U. S. Dept. of Agriculture
79
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17- Margalef, R., "Perspectives in Ecological Theory," Univ. of Chicago Press
(1968).
18. Smith, G. M., The Fresh-Water Algae of the United States, Second Edition,
McGraw-Hill, New York (1950).
19. Kudo, R. R., Protozoology, Charles C. Thomas, Co., Springfield, 111.
20. Provisional Assay Procedures, Joint Industry-Government Task Force on
Eutrophication, P. 0. Box 3011, Grand Central Station, New York (1969).
80
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SECTION IX
PUBLICATIONS AND PATENTS
No patents were produced in the course of the project. One publication was released
in May 1970 by the Lake Tahoe Area Council pursuant to the terms of the initial
grant. This report is:
"Eutrophication of Surface — Indian Creek Reservoir. First
Progress Report (FWQA Grant No. 16010 DNY)." Lake Tahoe
Area Council, South Lake Tahoe, Calif., lil pp. (May 1970).
81
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SECTION X
GLOSSARY
The following list represents the sense or context in which various terms and
symbols are used in this report, without specific regard to generalized or
standard definitions.
Benthic Sludge - Accumulated organic and organic sediment on the bottom of the
reservoir.
Benthic Invertebrates - Invertebrate organisms living in or upon the benthic sludge.
Bioassay - Laboratory measurements of the effect of nutrients or other factors on
the rate of growth of a test alga under specified conditions.
Biostimulation - Increase in the expected or normal response of an organism as a
result of the presence of some growth stimulating factor.
Conservative Element - Chemical element not significantly removed or increased by
chemical, physical, or biological processes.
Denitrification - Reduction of nitrate or nitrite to nitrogen gas by aerobic
bacteria living under anaerobic conditions.
Discharged, or Released, Water - Water purposefully released from Indian Creek
Reservoir for irrigation use.
Eutrophic - Nutrient rich condition of water.
Grazers - Aquatic animals which eat plant material, e.g., herbivorous zooplankton
such as Daphnia.
Hypollmnion - Region below the thermocline in a body of water.
Impounded Water - Mixture of influent reclaimed water and surface runoff plus
precipitation stored in Indian Creek Reservoir.
Infiltration - Movement of water downward into the soil through the soil-water
interface, or bottom, of the reservoir.
Influent Reclaimed Water - Domestic sewage effluent exported to Indian Creek
Reservoir after advanced treatment at the South Tahoe Public Utility District's
reclamation plant.
Limnology - The study of physical, chemical, biological, and environmental inter-
relationships in fresh water, particularly lakes and ponds.
Mechanical Aeration - Bubbling or air through the impounded water with the purpose
of saturating it with oxygen in equilibrium with the atmosphere.
Mixing - The intermingling of water masses in Indian Creek Reservoir so that
passive materials such as chemical constituents are uniformly distributed
horizontally and vertically when the reservoir is well mixed.
Nitrification - Oxidation of ammonia to nitrate or nitrite by specific bacteria,
called nitrifiers.
83
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Nutrient Budget - The algebraic sum of the effect of all factors which add or
subtract a specific plant nutrient, such as nitrogen or phosphorus, in the
reservoir, i.e., an accounting for all inputs and outputs of a particular nutrient.
Nutrient Recycling - Movement of nutrients through the natural cycle of growth and
decay of organic matter.
Oligotrophic - Nutrient poor condition of water.
Plankton - The host of free living microscopic plants (phytoplankton) and animals
(zooplankton) in water.
Productivity - The rate of change of biomass with time in a system, expressed in
amount per unit area or unit volume, e.g., Ibs fish per acre per year.
Secchi Disk - An 8-inch diameter white disk used to measure the clarity of water
in terms of depth below the water surface at which it disappears from sight of
the observer.
Seiche - An oscillating wave motion in the reservoir caused by winds.
Toxicity - The presence of factors which decrease or inhibit the expected or normal
response of an organism.
u-u - Maximum rate of increase in algal cell numbers or mass during a 5-day flask
T5Toassay.
X^ - Algal cell count at the end of a 5-day bioassay.
SS5 - Dry weight of suspended solids in flask at end of 5-day bioassay.
8k
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SECTION XI
APPENDIX
Page No.
Table 13: Indian Creek Reservoir Analyses 86
Table lA: Measurements of Vertical Distribution of Water
Quality Factors Throughout 2k Hours 9^
Table 15: Monthly Average Values of Quality Factors in
Indian Creek Reservoir Water (C) Observed by
LTAC Demonstration Grant Laboratory 95
Table 16: Benthic Organism Survey, Indian Creek Reservoir 96
Table 17: Maximum, Minimum, and Average Values of Quality
Factors in Reclaimed Water (Computed from
Monthly Reports by South Tahoe Public Utility
District)
Table 18: Maximum Growth Rates and Cell Concentrations
Attained in Five-Day Flask Assays of Influent,
Impounded, and Discharged Water at Indian
Creek Reservoir 107
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TAB» X}
HBUI ens RHHWOHI UULZSES
CD
1266
10/J
"A
ig?.
•A
*/*
5/29
6A
6A9
6/a*
7/1
7Ao
7A7
7/»
Sunl*
if
f
A
A
B
A
Bc
S^
D
C
'
A
B
C
S-III*
a
c
S-III
B
c
S-UI
B
C
S-IH
B
C
S-III
B
C
S-III
fi
fr .
0.5 .;
5.5.}
6.5 •'
Bottoi
o!?"*1
B
t-nr1
B
C
B».
D-fU
n
»9.8
*9.8
50.X
50.*
50.5
50.7
50.T
rt-o
6600
960
SKMhl
OUk
n
5.5
3.8
3.0
6.T
6.6
*.8
7.2
8.0
7.3
7-2
6.0
TealMralura
Water
•c
17.0
18.0
18.0
18.0
18.O
19.0
22.2
22.2
22.2
22.0
20.6
lfl.7
X8.3
£2.0
23.1
Air
•c
30.5
30.5
50.5
30.5
29.4
Unflltartd Suplti
Butt.
Soli**
2.22
12.25
l.*9
3-22
0.6*
6.89
6.52
3.26
0.86
12.12
O.63
1.92
3.07
0.53
5.8*
2.82
0.87
7.86
2.66
l-5«
*.57
9.36
3.45
5.86
4.67
3.49
15.71
4.89
1.23
0.96
3.58
2.58
0.85
Suap.
Solids
•8/1
0.96
3.15
0.64
1.03
0.6*
2.11
2.8k
2.52
0.47
8.00
0.66
0.77
1.74
0.53
2.83
1.80
0.66
2.'66
1.30
3.46
3.0k
2.22
2.25
2.9*
2.35
4.23
1.84
0.90
0.89
1.00
1.09
0.31
Xltrogro
II M
Org.
U/l
*25
715
960
800
800
815
765
5*5
720
1380
650
725
860
*90
655
100O
365
860
1180
620
1060
12*0
6*0
675
950
UK,
M/l
2700
4300
8250
*750
1*250
4550
3600
19000
7125
*150
1*500
6200
3625
19250
3300
3600
171OO
4625
3225
20200
*375
5000
16000
5000
5125
13600
Tottl
Phos.
«/l
105
13*
99
100
134
127
35
205
179
4}
65
176
50
105
91
47
53
335
88
18k
179
1BO
2*
155
COD
v/i
**
21
2
< 1
-
-
18
20
15
9
42
-
-
29
32
31
29
3k
19
-
-
18
28
21
34
53
2*
2*
32
2>
33
53
23
SOD,
1L'
9
5
9
2
3
1
7
< 1
< l
< 1
10
6
6
2
< 1
2
4
2
3
7
5
< 1
8
4
< 1
6
2
2
7
2
< 1
2
3
3
2
t
2
*
6
2
< 1
5
2
< 1
10
6.8
6.9
4.3
6.7
6.6
2.9
7.5
8.8
2.1
8.1
6.9
1.8
7.7
6.7
2.6
7.8
7.0
3.1
6.2
6.7
5.6
6.6
6.0
5.4
Inert.
C
•8/1
26.0
27.1
48.0
25.9
25.3
41.0
27.1
24.8
46.3
29.7
25.2
48.7
27.1
S7.9
52.8
S8.5
26.0
31.4
26.5
26.9
26;5
26.7
26.7
30.2
29.3
24.0
25.4
4*.8
ae.3
25.1
5*.o
o.*5 K miiipor. mt«n« San.i.1
litrofail •> »
Org.
Bio
1625
1625
1*40
620
420
TOO
650
510
240
270
720
665
725
600
690
510
670
2*5
275
685
930
580
665
1565
5*0
1190
1130
1190
760
670
560
685
845
865
885
6S5
1050
10OO
590
1O90
1040
IB,
M/l
2120
6800
10500
10250
6150
5500
4250
5000
86
22
30
5100
3*00
4300
4200
4300
14900
4250
3100
21000
4500
3*50
10200
5650
3300
17800
3175
3350
1*900
4*75
3500
19100
*700
4625
4525
3850
3950
5300
5225
5750
3600
17100
2500
1850
7750
no.
2660
Ik60
7*0
11*0
220
360
88
1*5
10
7
6
83
6W8
312
262
282
*9
480
469
55
5*0
455
15k
300
260
28
520
500
18
275
215
100
20
21
19
22
23
20
22
1280
250
580
420
*50
450
Si
KbO
5690
2260
2010
48a
640
172
315
25
12
1O
257
1192
1308
918
1096
30
1240
1001
14
520
905
536
80
140
13
1720
1480
43
205
96
2120
21*0
S138
2137
IflBO
1500
1560
1710
80
1720
2*30
kiso
Total
7850
15575
15125
,lk84o
7*70
6920
5210
6110
631
261
316
6160
5905
6000
6}70
15*89
66*0
*615
2134*
62*5
5740
11470
6695
5065
18381
6605
6*60
15*51
61*5
5365
20056
7350
7*56
72k*
6695
6955
8065
7632
7255
6610
1WO
5250
5820
13390
fttoephorui
II F
P04
46
*3
130
1*0
60
67
,
10
18
25
19
< 1
59
77
63
62
112
80
33
150
135
5
66
1*1
5
8*
59
16
20
8}
148
86
72
53
16
45
121
llfi
61
122
850
5
128
Total
60
66
170
210
69
71
14
17
37
3k
31
6
77
98
78
78
122
118
35
158
13
77
160
21
97
92
40
34
109
28
160
125
105
92
47
72
150
146
69
980
155
17
150
Ca
«/l
?0.0
32.5
33.2
32.5
30.9
39.0
35.0
lk.1
6.2
7.3
34.8
15.4
16.0
15.5
15.6
33.6
3S.1
3k. 7
37.6
38.0
54.*
57.6
40.4
37.5
59.6
38.8
36.0
60.6
36.6
35.6
11.8
3k. 0
35.8
35.2
33.0
35.8
36-6
36.1.
36.6
36.0
56.6
37.k
35.6
65.8
01-
*3.8
52.*
50.6
23.6
16.8
21-9
20.0
1.8
1.6
1.*
21.1
19.4
19.0
17.5
18.1
27.0
17.*
16.0
25.5
18.8
1B.1
20.8
14.2
18.6
23.7
20.4
1S.1
26.4
26.2
19.7
JO.O
US. 9
21.1
21.4
19.9
22.1
21.1
20.7
19.5
19.0
29.7
20.1
20.2
26.2
r.
30
20
< 1
22
23
25
37
< 1
48
77
S*
2
20
16
12
7
26
9
16
18
55
30
L4
9
9
2k
17
< 1
16
18
17
*7
37
32
34
55
34
33
17
13
4
4
7
< 1
PB
8.9
B.I
8.3
8.3
fl n
8.1
8.8
8.4
7.7
7.4
7.3
8.9
7.8
8.0
7.8
8.0
8.2
6.0
8.1
8.5
7.6
8.0
8.2
8.0
8.1
S.o
7-9
7.9
8.1
7.8
8.0
8.8
8.3
6.3
6.3
6.3
6.2
7.9
7.8
7.6
6.1
8.2
6.0
8.2
7.7
C.CO,
•e/l
67.0
188.7
197.0
185.2
106.0
99.6
104.0
107.0
63.8
30.6
36.9
105.0
101.3
106.4
1O8.5
108.2
199.3
1D8.0
105.6
171.2
108.5
J03.5
193.0
125.9
105.1
203.6
108.*
111.6
219.8
113.8
1O6.2
131.0
110.0
112.0
110.0
111.0
111.0
121.0
119.0
96.0
106.0
1B6.8
117.7
10*.*
215.8
ConJ.
(»•*)
•hoi
37*
*40
400
*50
216
£19
229
238
10k
51
55
230
300
310
295
297
*98
5*7
350
500
316
300
425
502
275
430
550
518
500
332
290
570
288
295
290
520
326
325
553
527
323
540
328
32*
510
-------
taa 13 (Continued)
oo
Drte
7/29
8/5
8/12
8A9
9/2
9/10
9/16
9/25
10/2
10/8
10/16
10/24
lfl/30
ll/U
SanpLe
Tn»
B
L-in
B
L-HI
B
L-m
B
C
L-I1I
B
C
t-m
»'•"
L-UQI
ti
%
0.5 »
3.5 *
6.5-
B
C
L-III
B
C
L-m
B
C'
L-III
8
C
L-III
B
C
L-III
B
C
L-HI
B
C
L-III
B
C
L-III
Res.
Depth
ft
50.8
50.8
51-0
50.2
*9.3
*9.5
*9.6
»9.«
W.2
llS-Z
•8.6
*6.6
*8.7
*8.8
48.8
Solar
ft-c
*900
5*00
Woo
5200
4600
4600
4600
5«00
6OOO
4600
5500
5200
2200
WOO
1340
4400
4200
Secchl
Disk
ft
10.2
7-8
4.9
5.8
8.8
6,*
».5
U.o
4.2
.*•'
».6
3.7
4.2
6.2
7^2
9.2
Tfmpen
Mater
•o
£2.2
ao.8
20.3
20.0
21.0
20.5
18.5
13. k
ifl.2
18.0
16.5
17.0
16.0
U.O
9-5
9-0
9.0
8.5
«lr
•c
22.8
25.5
25.0
21.7
31.0
29-5
24.5
25.0
22.8
a*.5
25.0
20.5
12.0
15-5
11.3
16.0
Uafiltered Samples
Susp.
Solids
*S/I
*.03
1.57
3-36
2.56
0.55
1.09
5.75
o.*3
0.95
6.14
1.21
2.15
1.84
0.1.5
4.2*
2.17
1.09
9.75
1.59
0.41
5.82
4-.7S
0.6k
4.16
5.79
1.45
5.11
11.32
1.51
5.12
0.70
•
2.07
1.97
1.22
1.59
1.62
Vol.
Susp.
Solids
W/l
0.79
0.19
0.79
0.86
0.00
0.1.1
4.52
3-23
O.T3
5.16
1.05
1.33
1.17
2.11
1.08
0.86
2.35
0.69
0.41
1.81
1.33
a. 6k
1.35
1.67
1.41
1.61
3.2".
1. 16
1.55
0.71
-
1.04
1.33
0.72
0.76
1.61
Iltrogea
ss II
Org.
«/«
800
810
700
900
1180
740
933
1033
630
936
7*3
1067
1595
723
5165
*2JO
532
9*3
809
512
8*7
91*
532
766
809
2*9
1000
526
2*0
92*
603
1029
lj£l
9*3
IB,
«/<
*550
3000
9600
5000
2625
6750
5595
2355
16260
*590
13800
1800
5750
17350
3150
2320
13828
2320
2535
15*00
17*5
2585
15210
2*65
29«5
17030
2510
2510
15550
2560
18270
2200
2325
19*70
Total
Pbos.
«/I
255
5*
110
2lfl
*0
122
191
26
186
*7
115
70
*9
185
rJ
135
95
32
*5
80
T3
113
77
79
223
63
67
177
80
137
67
66
95
COD
»S/I
30
28
13
24
21
51
20
30
:
12
1*
2
17
13
13
15
1*
13
25
1
102
22
28
17
22
17
20
21
15
3
29
*8
s
50
*5
17
23
25
BOB,
««/«
6
1
< l
6
2
4
6
4
5
3
< 1
6
1
< 1
6
1
< 1
-
7
3
< 1
7
5
< 1
8
5
3
2
< 1
< 1
1*
2
< 1
< 1
7
1*
7
2
< 1
DO
•!/«
6.5
6.*
*.3
6.3
7.0
10.6
6.6
7.7
6.7
7.9
5.2
8.5
8.1
3.8
6.6
5.6
2.9
6.9
7.0
5.9
6-9
7.*
2.6
7.8
7-9
5.5
8.0
8.6
1.6
15.0
14.6
3.3
15.S-
15.0
3.*
10.1
10.0
3.1
Inorg.
C
«a/i
29.3
26.0
*8.9
31.2
26.2
44.3
23.5
26.9
53.3
31.3
2*.5
*9.1
28.0
26.2
**.o
28.6
23
31.8
31.6
31.3
31.6
31.3
31.3
30.5
30.0
63.6
29.6
30.9
53.2
53.9
29.*
30.2
*5.7
31.0
32.*
«o.S
30.8
30.8
68.0
31.2
31.8
61.2
33.1
3*.2
50.8
0.*5 i* Hiliipore Filtered Samples
nitrogen as »
Ore.
«/«
790
710
680
1D90
81O
530
7*8
1071
605
785
109O
990
1000
977
59*
U20
1132
*89
905
819
876
883
102O
776
11*8
1335
< 5
9*3
752
670
*?
1D2*
627
1532
532
886
776
56*
713
2*9
1277
977
589
158*
1*98
838
IE,
«/l
5250
3050
1210O
5100
2*00
6700
5355
2*75
15290
520C
2150
15&00
5525
5275
17250
2390
2990
19330
3015
3155
3060
2695
3*70
2990
4855
2655
12*40
26JO
28J5
UB70
2250
2660
136*0
9520
9115
16790
2535
29*5
17460
251D
33*0
1*350
2580
2650
17120
2510
3850
19380
K>,
«/•
2*0
280
110
240
310
*0
210
300
2
*50
281
175
350
210
70
*00
260
95
312
268
250
250
290
350
365
29*
380
300
15
290
1
350
270
19
310
420
12
290
260
*
260
310
9
170
120
3
Kb
«/«
1460
23*0
*090
1720
2570
7560
1850
2560
378
1730
2739
1765
2050
2250
850
2S60
2640
1*25
2668
2132
2350
231D
2270
2130
2375
2*26
138
2860
2600
150
3570
13160
- 81
470
1020
155
3510
2880
163
3710
3420
106
-5700
3070
71
3150
2860
56
Tatal
KB/I
7740
6380
16960
8150
6090
14830
8163
6*06
16275
8165
6560
16730
8925
8712
1B764
6770
7072
21339
6920
6374
6536
6338
7050
6246
87*3
6710
1258*
6813
65*7
12705
7072
7204
1*354
11B72
17*96
72*1
7011
17»9
7223
1*709
7S17
7207
17789
7*14
8328
20277
Fboephorus
«s P
F0»
«/«
170
9
68
189
15
i!3
1£0
1O4
iiO
1
60
52
32
53
44
27
47
»7
45
47
40
51
-48
*9
47
113
59
49
67
45
44
64
1
258
49
47
143
29
28
153
52
59
50
48
23
Total
«/«
230
30
79
200
34
117
1B3
1*5
125
29
89
60
*0
162
165
112
83
68
t
57
71
67
70
69
13*
78
85
62
56
91
92
**
28
*50
69
70
170
48
*1
160
62
65
1*8
59
58
33
Ca
•g/J
38.0
39.0
65.6
37.8
38.2
59.6
42.6.
59.0
42.0
y>.o
61.6
40.4
37.8
49.0
37-6
36.4
51.0
39.1
39.6
39-2
39-5
40.6
40.6
U.O
62.6
61.0
63.8
*1.2
61.6
41.3
40.6
58.0
41.7
42.1
37-7
39-6
43.*
59-0
40.0
U.o
70.8
44.0
*3.0
68.2
50. *
50.0
68.6
Cl"
OS/'
19.6
19-3
29.7
20.4
26.5
19.2
19.0
1B.9
25.0
21.8
23.0
30.6
19.8
20.4
28.2
19.4
19.*
19.7
*4.2
25.0
21.2
20.1
19-3
27.2
21.6
23.0
30.0
20.1
20.6
22.1
25-5
26.0
28.5
23.9
25.0
26.}
27.0
29.9
33.*
£3.7
25.6
31.5
26.1
27.3
24.9
Fe
US/'
17
7
7
7
7
10
5
2
25
10
< 1
15
7
ifi
22
8
7
22
37
22
36
22
33
33
53
25
< 1
7
27
16
30
11
17
15
9
4
12
8
I
s
9
11
13
pH
8.1
8.2
8.1
8.2
8.3
"7.8
8.0
8.2
8.5
8.2
8.1
8.2
7.9
7.7
8.0
8.0
8.0
7.9
7.8
7.9
7.8
7.8
7.8
7.8
8.1
8.1
8.1
8.1
8.1
7.7
8~5
8.2
8.0
8.2
8.1
8.2
8.1
8.1
8.1
7.9
8.2
8.2
B.O
7.9
7.9
7.9
AUc.
as
CaCO,
•I/I
122.0
108.5
203.7
130.0
109.0
'177.0
98.0
112.2
222.0
130.5
102.0
196.5
111.8
104.7
183.5
119.0
115.0
185.0
127.0
126.0
125.0
126.0
125.0
125.0
127.0
125.0
265.0
123.2
128.6
212.8
22*.5
122.5
125.8
190.*
129.0
155-2
253.2
128.5
128.3
272.1
129.8
152.5
255.0
132.5
156.8
203.2
Cond.
-------
TULB 13
D.t«
11/26
12/Ifi
iffi
1/5
Tine
3.5.
6.5.
9.5.
B
C
L-HI
B
C
L-ln
c
L-m
B
c
L-m
B
C
L-HI
0.5.
3.5.
6.;.
9-5 «
B
C
L-m
c
t-m
c
L-m
c
L-m
8U. 1
0.5.
£.5.
15 m
St.. 2
0.5 .
3.5.
«.5.
10 m
C
L-m
Rei.
Depth
ft
1.9.0
1.9.1
1.9.2
1.9-9
50.8
5».l
54.6
54.6
55.5
55.2
Solar
rt-c
5000
4000
4000
4600
2600
2000
6*00
6400
6600
5200
Seccfc
Disk
ft
9.2
10.0
11.3
8.8
9.2
2.7
2.8
3.2
2.8
2.8
%*9«rature
Water
•c
6.3
6.2
6.1
6.5
5.0
4.0
3.0
4.0
4.2
3.5
3.5
3.5
4.a
4.0
5.0
6.8
6.8
6.8
6.8
6.8
6.8
6.8
6.T
8.2
Air
•c
11.8
9.0
11.0
11.0
-0.5
lo.o
5.0
8.0
4.2
12.0
Solid*
f/t
0.80
1.65
0.53
:
1.01
1.19
1.45
1.39
1.80
1.00
1.55
1.81
1.71
5.9
7.11
8.07
7.58
1.56
5.23
8.98
1.47
10.88
1-55
11.21
12.50
12.72
10.59
9.1.2
12.57
5.99
7.69
1.92
Vol.
Susp.
Solids
•»/'
0.55
0.73
0.87
-
0.78
0.57
0.96
0.68
0.78
0.79
0.58
0.53
1.15
1.6)
1.80
3.05
1.1.9
3.15
6.37
1.35
6.02
8.07
1.19
9.96
8. 97
1O.05
6.81
5.29
12.57
5.50
1.65
nitrogen
as H
Org.
US/I
1*3
532
169
809
771
627
981
943
6*7
1O96
575
991
733
10W
1125
1297
761
857
61.2
1297
1402
819
1130
1622
522
416
1177
1191
1287
383
91*
612
880
1096
1106
HH,
If/I
2335
3350
IBS 58
22OO
281.5
20570
2510
2680
22730
29*.
306
20350
1.975
2885
25170
3710
3015
2585
2825
20280
3110
3805
21670
2705
3180
21530
3300
5470
31.70
J350
3300
2680
3060
3540
20330
Total
M/t
*
85
85
64
60
1J6
67
67
706
82
81.
161
79
68
132
92 .
92
64
61
17*
38
36
72
34
35
84
49
39
56
43
50
46
53
31
34
362
lea
COD
»*/l
36
24
22
15
8
< 1
< i
15
< 1
9
20
26
32
45
< 1
1
7
< 1
18
12
6
15
5
15
19
28
18
19
20
23
34
BOD,
•«/'
5
< 1
< 1
5
2
< 1
5
3
< l
4
1
< 1
3
2
< 1
3
2
< 1
1
< 1
3
4
< 1
6
4
< 1
5
4
< 1
CO
»g/J
9.9
9.4
1-9
9-5
10.3
1.4
11.1
10.8
1.8
11.7
10.6
2.0
1O.6
10.9
0.7
10.9
11.2
11.2
11.1
10.5
10.9
8.2
10.8
0.9
10.0
11.8
1.9
10.9
ljO.8
3.7
13.8
15.1
14.0
14.5
12.7
14.1
13.4
9-9
12.2
Inorg
C
»e/i
34.0
34.6
32.5
32-5
51.7
31.8
52.2
28.0
28.3
48.1
30.9
33.6
44.1
34.0
34.1
59.4
33.2
33.7
59.0
30.5
30.3
30.4
30.5
30.2
30.5
29-6
30.5
60.0
50.8
31.5
62.1
30.2
30.3
54.2
3i.2
32.4
52.2
32.0
32.2
32.2
31.8
30.6
31.2
0.45 u milipore Filtered Saaples
Iltn*en >a I
r/i
1087
1326
1249
292
471.
378
321
1005
895
570
819
1058
594
804
957
603
1240
723
1OOO
632
756
742
723
928
867
866
91*
7TO
1115
1249
752
1058
962
«4l
1154
1_L06
1DOO
1OOO
1192
1034
1O96
1J.44
804
«Hj
«/«
2920
2825
3110
2680
1770
2660
16270
2440
2415
2O19O
3300
31flo
21120
3060
5960
20530
5550
3420
28250
4o65
4065
4530
4115
5540
4045
2465
3230
19420
3160
3730
21290
3300
3705
20190
3060
4140
3420
3060
4115
3850
3780
3350
3945
•0,
If/I
156
uSi
155
155
170
145
124
105
1DO
5
160
190
13
200
170
65
120
110
4
160
150
130
150
230
l£o
167
133
18
125
70
6
144
115
5
TO
2
65
76
72
TO
190
130
16
no,
w/«
444
539
445
445
3390
2975
1426
3895
3380
13
4040
3550
117
3660
3670
95
3480
3486
31
3770
3570
3870
4146
3810
3580
3681
3715
87
4115
3850
40
4136
3945
265
3704
3783
3694
3995
3764
4148
4670
4410
Total
US/'
4607
4851
4959
3582
5804
6178
18141
7445
6790
20778
6319
7978
21844
7924
10757
21293
10390
7739
29265
8627
8541
9272
9134
8508
8652
7179
7992
20295
8515
8899
22088
8638
8727
21101
T988
9106
8180
8120
9147
9104
8956
9354
9289
22893
Phosphorus
it P
P04
1*1 1
48
49
48
50
60
71
60
38
40
57
50
45
568
55
54
i£7
60
51
60
56
54
53
92
58
52
36
27
157
8
5
24
a
10
32
7
6
4
6
4
4
4
Total
UK/I
58
64
61
67
66
82
61
60
69
71
62
77
70
134
70
60
71
61
69
65
101
77
65
50
37
203
15
13
29
16
19
48
2§
15
17
16
ID
10
«//
50.9
49.1
50.8
48.9
51.4
48.0
43.3
42.6
59.4
50.9
50.2
42 1
49.8
49.0
70.6
52.6
49.6
70.0
45.0
45.8
45.4
46.6
46.4
44.4
48.6
47.4
69.4
46.0
47.4
59.8
49.6
47.4
59.8
49.6
49.2
52.0
49.0
49.0
49.0
51.0
51.0
Cl"
"«/*
26.7
27.0
25.9
36.6
23.2
22.5
23.2
25.5
31.4
26.4
24.7
21.6
18.8
30.7
28.1
33.0
22.9
17.8
15.2
17-2
24.4
15.3
23.2
31
23.0
1B.O
22.9
22.1
26.0
20.7
ia.i
20.8
21.5
22.9
23.2
15.7
14.5
Fe
mff
11
9
11
19
6
< 1
2
5
9
2
7
< 1
<: l
2
7
9
la
6
5
6
4
10
< 1
3
2
< 1
< 1
< 1
12
3
< 1
4
< l
11
< 1
< 1
< 1
PH
8.0
7-9
7.9
7.9
8.0
8.0
8.1
8.2
8.2
8.0
7.9
8.1
8.1
8.1
8.2
8.1
8.0
8.0
8.0
8.0
6.0
8.0
8Jo
8.0
8.1
8.1
8.4
8.5
8.4
8.3
8.3
8.3
8.4
6.3
8.3
8.4
8.4
8.1
8.3
Alt.
as
CaCOj
136.0
138.0
130.O
130.0
132.1
132.5
116.7
118.0
132.6
134.6
136.0
136.4
138.0
140.3
127.O
126.3
126.7
127.0
126.0
127.0
123.7
126.7
128.5
131.5
126.0
127.0
225.0
134.0
135.0
1>.0
133.0
134.0
134.0
127.5
129.8
Cond.
(ID'*)
415
400
380
380
410
385
360
390
414
405
400
385
400
382
366
353
4a>
420
340
368
321
330
520
580
565
340
410
380
360
394
400
-------
00
VD
Ditg
1970
^/15
Ik/23
4/30
5/7
5/1?
5/?7
6>
6/16
7A
7/T
Sample
in"
c
III
0.5 m
3.5 m
6.; m
11.0 m
C
III
0.5 m
3.5 m
6.5 m
U..O m
C
III
C
III
0.5 n
3.5 a
0
III
C
III
0.5 o
3.5 m
6.5 *
10.0 m
C
III
0.5 m
3.5 m
6.5 a
IX). 0 m
C
III
0.5 m
3.5 m
6.5m
10.0 m
C
III
0.5 m
3.5 »
6.5 »
10.0 m
c
III
0.5 a
3.5 »
6.5 •»
10.0 a
Dei.
Depth
ft
55.6
55.8
55.8
55.8
55-6
55.6
55.3
5*. 9
5*. 4
5^.0
Solar
rt-«
Sec cAl
Dlik
ft
19.3
19.1
19.0
16.0
13-5
5-4
12.3
8.3
17.2
17.8
ftnperetizre
Vgter
•c
10.0
9.2
8.9
8.9
8.9
10.5
10.5
9.5
9.0
8.7
9.5
14,0
14.0
13-5
13. *
16.5
16.5
16.1
13.0
12.0
19.5
16.0
17-0
14.3
12.0
17.0
15.5
15.2
15.0
1*.5
18.5
18.5
17.8
17.5
17.0
21.0
21.0
19.7
18.0
17.2
Air
•c
7.0
15.0
11.0
18.0
15-7
16.5
26.5
19.5
23.5
23.0
Utafilt«r«i Staples
S*up.
Solid*
mil
0.84
1.72
0.97
1.06
1.46
1.88
2.6L
5.06
0.90
1.42
0.96
4.17
2.93
1.66
2.71
2.99
5-88
6.20
4.09
3.14
3.46
2.22
3.70
2.87
3.15
7.70
3.37
2.89
3.71
3.73
5.91
3. IB
1.31
1.91
1.78
1.67
2.03
2.15
1.26
3-58
Vol.
Siup.
Sol Ida
til
0.58
1.52
0.75
0.94
1.34
0.84
1.45
2.27
0.53
0.88
0.4«
2.77
1.11
0.51
2-15
1.46
4.75
4.84
2.29
1.99
2.25
1.35
2.71
2.31
2.50
2.48
2.96
2.05
3.10
3.02
5.00
2.39
0.86
1.1.5
1.47
1.26
1.63
1.60
0.75
1.88
nitrogen
as S
Org.
*/«
ug/5
Total
Phoa.
ug/l
COB
•til
12.5
16.8
8.4
15.2
15.7
15.3
BOD.
mil
DO
•>e/i
8.9
3.0
9.2
11.8
8.0
8.8
8.5
1.6
7.8
8.1
7.4
7.8
8.0
1.9
7.8
1.8
8.5
8.4
9.8
6.5
11,2
3-8
11.6
U.2
5.8
3-7
10.5
1.4
11.1
8.6
4.6
1.4
11.6
5.8
10.2
9.2
7.8
5.9
7.0
6:1
6.8
5.9
4.6
6.8
6.8
6.5
4.4
4.4
5.9
Inorg.
0
•til
33.1
60.2
32.4
32.2
33.1
32.9
32.4
56.6
32.3
31.6
31.6
31.3
32.3
51.7
33.3
52.5
32.3
33.3
32.3
55.0
34.5
53-5
34.5
31-8
33-8
34.3
29.5
56.9
29.0
29.2
35-3
37.0
31.2
43.5
31.2
31.2
31.9
34.1
31.2
48.5
30.3
31.0
32.1
32.2
31.2
58.5
30.8
30.7
30.3
33.3
| 0.45 u (ttlllpore Filtered Sample!
Hltrogea BB H
Org.
MS/'
895
733
771
857
957
900
1235
761
1120
1010
1048
1154
1010
632
905
1077
1130
1020
1000
814
1015
751
1168
1034
1010
910
991
890
972
1000
517
• 835
1120
737
1197
1230
1575
1192
857
512
809
957
905
953
809
680
HHj
uS/'
2920
12344
3420
3300
3350
3395
3660
18850
3470
3780
3450
3540
5240
19140
2965
11390
3350
3255
3397
17940
3395
16889
3710
3635
4735
5550
2630
14550
2460
2705
4520
4X5
2275
17700
304o
2440
3135
4350
2705
15020
3160
2845
3160
3110
2920
25160
B0a
MB/'
70
3
75
75
70
80
120
21
95
115
100
95
115
50
135
27
130
140
110
12
105
13
125
130
llfl
100
185
15
160
150
135
120
138
41
135
105
145
155
595
38
130
170
80
122
162
17
SOj
pg/'
3370
29
3625
3665
3950
4040
4500
89
3885
3905
4080
3985
4l05
93
4405
59
4450
4360
3810
84
3815
39
4235
4070
3650
2860
4175
47
4280
3930
3625
3000
31B2
109
2865
1B55
3135
2405
2245
12
2710
1030
1200
1718
1758
18
Total
U8/1
7255
13109
7891
7897
8327
8415
9515
19721
8570
881O
8678
8774
10470
19895
8410
12553
9060
8775
8317
1B850
8530
17692
9238
8869
9505
9420
7581
15502
7872
7785
8797
8258
6715
18587
7237
5630
7990
8062
6402
15582
6809
5002
5345
5903
5649
25875
Phosphorus
BB P
PO,
ug/«
10
26
9
13
10
10
23
9
21
21
21
21
35
30
22
16
20
22
21
23
7
10
5
37
56.
7
21
5
1
7
40
2
72
2
1
2
30
17
215
4
6
8
15
4*'
Total
ug/4
39
74
IB
19
18
IB
29
11
30
27
52
73
39
TO
47
48
50
49
12
16
15
14
43
70
44
35
62
10
14
56
a
81
10
9
9
44
17
251
14
20
37
28
10
442
Ca
=8/1
49.2
68.0
48.4
48.4
48.0
47.4
49.4
71.0
50.2
49.4
49.4
49.4
48.6
52.0
46.0
67.8
46.0
45.4
47.8
62.4
47.0
63.0
46.6
47.4
48.0
49.0
45.2
66.0
45.0
44.0
49.4
50.4
44.2
52.0
45.2
45.0
46.0
46.2
43.4
46.2
44.6
45.2
45.0
44.6
43.4
52.4
Cl"
me/I
19.6
21.5
23.2
24.0
22.8
22.8
12.9
25.8
16.4
15.8
17.6
19.6
21.4
34.8
18.8
41.7
22.3
21.5
40.7
52.2
28.7
38.5
21.1
23.2
18.5
20.7
20.2
29.0
1B.5
21.5
27.6
18.1
23.1
36.3
27.1
24.2
17.5
21.3
28.3
29.7
34.2
88.5
54.1
26.2
25.3
31.1
28.1
20.2
19.1
24.5
te
as/I
pfl
8.4
8.2
3.6
8.2
8.0
8.4
7.9
7.7
7.8
7.8
7.9
7.8
7.8
7.8
7.9
7.7
7.9
7.9
8.0
7.8
7.8
7.9
7.8
7.8
7-8
7.8
8.3
7.8
8.2
8.2
7.9
7.9
8.3
8.0
8.2
8.2
8.2
8.0
8.2
7.9
8.1
8.1
8.1
8.1
8.2
7.9
S.I
8.2
8.2
8. 2
Ali.
as
CdCO,
•til
136.0
251.0
155.0
154.0
138.0
137.0
129.7
226.2
129.0
126.5
126.5
125.2
129.3
206.8
133.0
210.0
129.0
133.0
134.5
220.0
138.0
214.0
138.0
139-0
135.0
137.0
122.8
227.5
121.0
121.5
141.0
148.0
130.0
lfll.1
130.0
130.0
133.0
142.0
130.0
194.0
126.3
129-2
155.7
154.0
150.0
234.0
128.5
127.8
126.2
138.8
Good.
(ix>-«)
mhos
396
616
429
396
585
376
518
707
472
452
460
466
. 348
4o5
380
508
572
561
426
644
416
558
4oS
423
437
437
466
673
451
448
479
498
583
510
596
384
394
415
429
594
468
429
438
44o
436
670
458
445
416
463
-------
TABLE 1) (Continued)
Date
19TO
TM
7/21
7/30
8/7
8/14
8A9
8/26
9/>.
9/10
S«.ple
TJP«
C
III
0.5 •
5.5 •
6.5 «
10.0 •
c
111
c
III
0.5 »
3.5.
6.5 »
10.5 >
C
III
0.5 II
3.5 »
6.51
10.0 .
c
III
0.5 •
3.5 »
6.5.
9.5 •
C
III
0.5 •
3.5 •
6.5.
9.5 .
C
III
0.5 •
3.5 «
6.5.
9.0 .
c
in
0.5 .
3.5.
6.5.
7.5"
c
III
0.5.
3.5.
6.5.
7.5 .
Rea.
Depth
ft
53.8
53.6
50.7
1.9.2
48.o
»7.2
W.9
«4.7
M.9
Solar
rt-c
Secchl
Dirt
ft
14.0
10.6
6.3
5-2
7-2
7.8
7.*
6.7
9.6
Temper*
Water
•c
21,0
21.0
21.0
19-5
17.8
22.5
20.8
20.8
20.5
20.4
20.0
20.6
21.7
21.7
21.0
20.7
19.8
21.3
21,3
21.3
20.1.
19.8
20.0
20.0
19-5
19.0
19.0
17.7
17.7
17.7
17.7
17.7
lfl.2
IB.?
18.0
17.5
17.0
Air
•c
IT.*
26.0
S3.0
26.8
27.0
27.5
23.0
25.0
28.0
Unf ilterea Samples
Stup.
Solid!
til
2.*7
3.35
2.45
1-57
2.58
1.13
3.65
2.35
2.38
1.15
2.57
1.10
2.80
0.88
3.02
1.8k
2.25
l.lfl
Vol.
SllBp.
Solid*
°6/«
0.97
2.11
1.08
0.88
O.G8
0.55
1.22
1.51
0.89
0.77
0.98
0.83
1.00
0.52
0.86
1.25
0.87
0.86
nitrogen
aa H
Org.
MB/I
KB,
US/I
Total
Pnoa.
«/.
COD
•til
11.6
15.8
17.2
21.1
12.6
9.3
17. T
8.1
12.5
7.3
10.2
9.5
17.3
8.8
12.1.
11.1
12.0
10.6
BODg
«g/l
DO
«S7<
6.6
5.2
6.6
6.6
2.5
1.5
7.1
l>.8
6.5
2.7
6.9
7.2
6.9
5.9
7.9
2.1
7.1
7.5
a.i
5-4
7.6
1.5
7.8
9.8
7.5
3.3
6.9
6-7
6.5
*.5
2.1
7.2
1.1.
7.6
8.6
8.6
6.0
8.3
2.2
7-9
7.8
7.6
8.8
8.2
0.8
8.6
8.8
10.9
6.9
Inorg.
C
««A
Jl.O
56.7
32.1.
31.7
33.0
37-3
31.0
53.3
32.3
60.2
32.8
32.2
52.3
32.*
46.6
33.1.
32.9
33.2
33-6
35.0
66.3
34.6
60.7
3U.li
34.5
34.6
53.0
35-0
64.1
35.5
36.3
36.5
38.6
34.2
66.4
55.0
3*.5
34.3
34.*
35.0
62.1.
34.6
34.2
34.2
31-.2
0.1.5 „ Mlllipore Filtered Sample o
Nitrogen as If
Org.
«./«
1000
737
1058
355
766
556
953
503
1532
359
685
465
8*7
9llt
1B30
672
»H3
ug/«
k305
33500
2870
215*0
3160
25560
2870
29260
3590
21060
3205
23440
1175
1BB60
3105
20300
IBs
pg/«
165
31
150
63
175
9
230
131
220
102
£fi5
*
365
Ik
380
7
'1
HO,
ug/(
3315
H9
21.10
U2
2305
21
21.90
261.
2U80
296
1571.
61.1
2575
606
5580
1113
381.5
789
Total
ug/<
8785
3U.17
6188
22,000
6"«6
261W
651.3
30178
7822
21B19
68JO
2*525
5962
20891.
8295
21767
FhoaphoruB
ee P
PO.
u»/l
1
91
2
140
1*
252
8
72
2*
52
25
289
3
71
12
ks
20
ivr
Total
u«/«
10
98
19
161
25
278
32
168
35
23*
38
295
13
80
25
55
l>7
156
Co
•ell
k6.8
55.6
"42.6
U6.I.
1.3.1.
57.*
*3.0
Wl.O
52.*
i5.0
W.2
*3.2
77.0
I.1..1.
55.6
U.o
*7.2
cr
K/l
SD.9
».2
20.9
20.2
20.9
20.6
JO. 7
S3.6
15.9
31.2
25.9
21.*
30.6
2*.8
27.6
21.5
23.9
26.0
2*. 5
25.1
21.7
19.5
2*.5
2k. 1
25.*
Jl.l
28.5
27.2
25.8
32.'0
29.9
2*.l
25.6
22.9
26.7
23.5
22.7
31.2
25.8
22.7
19.9
26.0
15.3
29.2
20.2
22.6
19.5
23.2
23-*
Fe
Ug/I
PB
8.1
8.0
8.1
8.1
8.0
8.0
8.2
8.1
6.2
8.3
8.5
8.3
8.2
8.2
8.2
8.3
8.2
8.2
S.2
8.2
8.2
8.1
8.2
8.3
8.2
«.2
8.2
8.0
e.x
7.6
7.9
7.9
7.9
7.9
8.2
8.1
6.3
8.3
8.3
8.3
8.2
7.9
8.1
6.1
8.1
8.1
A Ik.
as
CaCOa
«/«
1£9.0
236.2
135.0
132.0
11.0.2
155-6
129.0
222.0
13*. 5
250.9
136.5
13*. 0
15*. 5
135.0
19*. 0
139.0
137.0
138.5
ll*. 0
1*5.7
276.2
144.2
255.0
1*3-5
11.3.9
Ik*. 2
137.6
1*5.7
256.5
141.J
H5.2
146.0
15*.*
142.7
276.6
145.7
143.7
142.9
143.5
145.7
249-5
1U.O
142.7
142.7
1.2.7
Good.
(io-«)
•bo«
U62
660
41.2
41.1
449
462
499
499
1.1*0
696
412
702
405
456
*53
544
382
556
460
*72
462
474
456
621
456
*58
467
456
386
719
*13
*13
*23
417
530
660
612
515
505
526
**
636
»T7
488
472
*51
-------
TABLE 15 (Continued)
VD
tot.
13|0
9A7
9/23
IDA
10/9
10/1*
10/22
10/28
U/»
11/11
sari.
Tne
c
iii
o.s •
5.5-
0.5-
8.0 »
c
IU
0.5 »
3.5.
«.5-
8.0.
C
in
0.5 •
5.5.
6.5.
8.0.
C
0.5 .
6ls«
8.0.
C
ni
0.5.
5.5 •
6.5.
8.5.
C
in
0.5.
5.5.
6.5.
8.0 .
C
III
0.5.
3.5-
«.5»
8.0.
C
in
0.5.
5.5.
6.5.
8.0.
c
111
0.5.
5.5.
6.5-
8.0.
B«l.
Depth
R
44.0
U.I
43.5
4*,.0
44.0
44.2
«*.»
4*.9
4J.O
SolAT
ft-C
Secchl
Ola*
n
1J.6
17.8
ia.4
19.2
20.2
13.3
21.5
11.5
14.0
Teavtntnn
Hater
•c
16.5
16.0
16.0
M.o
1*.7
15.0
15.0
ih.o
1».0
14.0
15.0
14.3
i4.o
13.8
13.5
13.0
13.0
13.0
12.2
12.0
13.0
13.0
12.8
12.2
12.1
9-5
9.5
9.5
9.5
9.5
8.0
7.5
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.4
7.*
7.3
7.1
7.0
Air
•c
25.0
25.0
23.0
21.5
19.0
9.5
14.0
6.0
11.0
Sup.
Solid*
•g/«
1.70
1.3*
0.82
1.87
0.69
1.18
2.10
0.6k
0.47
0.65
2.06
o.»3
1.09
1.22
Vol.
Susp.
Solid*
«/<
0.88
1.06
0.52
1.46
0.49
0.95
0.65
0.54
0.41
0.1.7
0.5k
0.42
O.U
0.90
Ibflltcnd Suplee
nitrogen
• 8 H
2&
BU
ug/l
Total
Fbos.
A/1
COD
«/«
17.5
6.5
10.9
7-9
14.2
10.9
14.0
10.6
7-7
9.6
6.l>
10.3
7.9
12.4
8.8
9.1
3.4
BOD,
•e/'
00
•«/«
8.5
1.5
8.0
9.»-
10.9
8.1
8.2
1.5
8.2
8.6
9.2
8.0
8.7
1.6
9.5
9.1
9.0
9.6
'•?
9.6
9.6
9.8
9.7
8.9
1.9
9.0
8.9
9.8
9.8
9.1
1.5
9.0
9.0
8.7
8.7
9.8
1.6
9.8
9.6
10.0
10.0
?:1
9.3
9.8
10.4
9.6
10.1
1.9
10.1
10.8
10.0
10.0
Inorg.
•g/I
33.1
58.4
33.6
33.5
33-0
3J.O
34.2
58.1.
33.8
33-9
33.1.
33.1.
33-5
52.5
33.9
32.3
33.3
33.0
30.7
73.ll
30.2
28.3
26.li
32.2
«4.0
31.9
. 32.2
31.7
31.7
32.3
67.1.
33.0
32.3
33.8
31.9
35.0
73.9
32.4
34.2
34.2
33.8
31.6
6k.2
33.9
34.1
3*.J
33.8
35.2
77.1.
35.2
3* .8
3lt .8
3*.*
0.1.5 u Hllllpore Filtered Saaplea
Nitrogen ea R
Org.
ug/1
833
6:6
960
601
1329
120
KA6
915
505
626
657
1031
1.50
1253
<&>
691
328
m,
ut/t
illlo
5075
27580
3335
17680
W50
3635
20500
1.31.5
231tO
kl£5
2USO
51.30
26260
3410
20900
Hfe
-«/«
?95
22
260
15
250
57
275
230
U
200
1.
175
2
195
k
180
7
«0s
-g/«
a«25
looe
23?0
527
3550
396
U05
3390
551
2920
656
281.5
kk)
1.125
536
3300
1.13
Total
ug/J
7288
18316
8615
26521
atox
1B555
10576
8170
21560
8091
2U.57
8216
22015
11003
27280
7581
216U8
PhosphoruB
a* f
TO,
Alt
22
13
25
7
119
5
3
1.9
2
k2
7
17
15
72
Ik
79
Tot.1
u«/(
27
29
51
IB
1*9
12
12
67
9
55
29
3k
22
100
23
89
Co
•«/«
kfl.V
56.6
^6.0
57.8
U.6
51.8
39.1.
•0.8
6X.8
1.5.8
69.8
46.0
83.0
kg.8
61.0
51.6
81.8
Cl"
I/I
19.2
27.2
19.2
17.2
?7.6
19.5
15.0
19.k
15.2
20.5
24.2
1B.O
20.0
28.5
24.6
55.7
36.8
2».3
50.8
32.1.
33.2
50.6
50.9
31.0
31.1
32.0
33.8
29.7
32.9
30.1
31-k
32.1
35.1
32.k
31.5
31.5
30.9
2&.6
28.2
28.3
26.5
25.5
23.1
29.1
30.0
31.6
29.9
30.3
30.3
F*
Mil
Pa
8.1
8.0
8.1
8.1
8.1
8.1
8.k
8.0
8.1.
8.1.
8.1
e.i.
7.9
7.3
7.8
8.0
7.9
7.9
7-9
7.B
7.9
8.0
7.9
8.0
7.6
8.0
8.0
8.0
8.0
8.0
7.6
7.9
8.0
7.9
6,0
7.9
7.8
8.0
7.9
7.9
7.9
8.2
7.8
8.2
8.1
8.0
8.0
8.1
7.6
8.1
8.1
8.1
8.1
AH.
as
CaCOa
til
137.8
21.3.1.
lko.2
139.7
137-k
137-k
U2.".
21.3.1.
lkO.9
Hi. 3
159.0
13J.2
1>.0
210.0
135-5
13k.k
135.1
152.1
122.8
113.7
L20.6
117.9
105.5
134.0
255.9
132.9
134.0
132.0
132.0
134.5
269.5
131.9
134.7
155.0
133.1
140.0
295.6
135.2
136.7
136.9
135-0
1U.3
256.9
141.2
142.1
142.8
140.8
146.6
509.6
146.6
145.2
144.8
143.5
Cond.
-::
5=;
— ic
4cC
^C2
;s
3£:
^c-^
52i
-.;2
^:-
ii-
*c~
It —
'-£*
-------
TABU 13 (Continued)
VD
ro
Date
1970
11/lfl
11/A
12/9
IS/15
1971
1/6
1/37
2/10
2/22
3/9
gupie
Tfff
C
III
0.5 »
3.5 •
6.5.
8.0.
Grab C
III
C
III
0.5 »
3.5 »
6.5 »
6.5 *
C
III
0.5 »
3.5 •
5.0,
0
III
0.5 m
3.5 «
6.5 >
7.5 .
C
III
0.5.
3.5 «
7.0.
C
III
0.5 .
3.5.
6.5 .
9.5.
C
III
0.5 •
3.5.
6.5 •
9.5 »
C
III
0.5 .
3.5.
6.5 .
9.5 «
Bet.
Depth
ft
45.1
1.5.3
46.7
46.9
W.O
1.9.6
50.0
50.6
51.0
SolAT
ft-c
Secchl
EUk
ft
18.0
11.6
15.0
17.0
16.0
6.0
5.0
4.0
Teqierature
Water
•C
6.8
6.8
6.5
6.2
6.1
7.8
2.8
2.8
2.7
2.5
2.5
2.7
2.7
2.7
2.7
2.9
2.9
3.0
5.5
3.5
4.0
4.0
Jl.O
4.0
5.5
5-5
4.8
».8
• .6
5.0
5.0
5.0
5.0
4.9
'.5
4.5
4.5
it. 5
"••5
Air
•C
8.5
19.0
6.0
12.0
-3.0
9.5
17.0
6.0
11.0
Unr lltered Saag>le»
Su«l>.
Sollda
•tit
1.01
1.95
6.20
1.45
3.87
1.67
1.27
0.48
0.93
J.67
1.07
3.06
5.05
0.54
6.14
1.60
6.95
4.43
Vol.
Soap.
Solldi
«S/<
0.63
1.65
1.83
1.18
0.69
0.36
0.41
0.30
1.44
0.88
1.73
4.05
0.53
4.80
1.06
5.52
2.11
nitrogen
u X
Ore.
Vf/l
m,
ve.li
Total
pboB.
MS/*
COD
me/I
10. 1,
7.6
18.6
8.9
18.8
9.0
12.5
25.4
10.9
30.3
11.0
9.3
15.1
14.0
15.2
l£.2
20.5
10.2
BOD.
mt/1
DO
1/1
10.3
1.3
10.3
10.1
9.7
9.4
9.5
1.7
12.9
2.6
12.9
U.I
U.o
10.9
10.5
2.9
10.5
10.5
10.2
14.2
0.3
14.2
9.1
8.5
9.5
12.8
0.6
12.8
12.6
14.7
15.8
1.4
15.8
15.2
15.4
16.8
13.1
0.5
13.1
1?.G
12.4
12.1.
18.7
4.0
18.7
12.9
12.7
11.5
iDorg*
c
t/t
55.9
70.9
35.7
35.0
35.4
35.6
37.7
70,7
37.2
71-6
37.9
37.9
37.9
37.2
37.3
71.4
37.5
37.5
57.4
40.8
76.5
40.6
40.1
41.3
42.1
32.7
74.0
41.1
40.6
40.1
44.0
72.3
48.7
47.7
50.9
45.8
40.3
75.4
40.8
3'M
40.8
to.8
72.1
41.6
45.8
41.6
4l.l
C»5 u Kllllpore mtered tStMflt,
Iltrogen «a «
Org.
Mil
795
295
850
113
722
172
604
46k
661
745
258
362
1021
160
896
458
777
196
n.
»*/'
4160
14640
3ltlO
17280
4590
1J460
4180
17180
6826
28000
2W»0
22620
3633
13600
4415
14900
6115
18200
HO.
.*/J
185
36
150
3
130
3
150
ID
34
< 1
65
8
62
5
45
>.
kl
It
Kb
Mj>
2995
394
3690
1B2
3190
IDS
2870
80
*g
2335
52
3193
315
2775
76
2658
124
Total
M/l
8155
15365
8100
17578
8632
13737
7801
1773k
10515
28790
5098
2303>«
811*
14060
8131
154>8
9591
18526
Ffeoopharus
19 7
PO,
alt
17
126
24
105
27
106
27
97
54
18
29
21
22
29
9
58
6
92
Total
mJt
50
139
>6
117
32
109
28
105
58
332
31
28
£3
49
£6
82
25
123
c>
til
48.0
74.6
46.2
71.2
50.8
77.8
i
:so.2
i 70.2
53.0
83.2
W).8
78.6
52.5
68.5
52.5
77.3
53.8
77.5
or
til
26.6
28.1.
24.5
26.2
27.6
25.0
51.6
52.3
34.1
29.0
30.9
29.9
30.8
2*. 3
30.1
30.3
28.3
27.9
27.2
27. 2
27.4
25.2
25.8
20.4
23.4
29.1
27.1
28.2
30.0
27.6
27.7
28.2
28.0
27.5
27.9
26. 0
30.3
28.9
28.4
26.0
30.4
29.5
27.9
27.2
Tt
*H
Pfl
S.I
7.7
8.1
8.1
8.1
8.1
8.0
7.5
7.8
7.6
7.9
8.0
8.0
8.0
8.2
7.8
8.2
8.2
8.2
8.1
7.8
8.1
8.0
8.0
8.0
8.0
8.1
8.0
8.0
8.0
8.1
8.0
8.1
8.1
8.0
8.1
8.1
7.8
8.3
8.J
B.u
8.1
7.9
8.2
8.2
8.3
8.2
All.
•«
CaCOl
til
l
170.2
268.5
173.2
ISO. 7
173.2
171.2
Con4.
(io-«>
•hos
388
562
IOG
589
382
387
"•33
681.
1.44
68k
477
1.64
475
469
464
631.
458
k78_v
1.76
44;
647
404
4ol.
^9
4 13
380
517
398
586
392
4,16
553
418
417
411
til
">93
650-
518
475
US
ua
717
183
k85
538
UJ
-------
TABI* 1} (Continued)
\0
Data
3A5
•"*
5/5
5A7
S«Mple
c
in
0.5 .
3.5 •
6 5 •
9*5 *
c
III
3.5 •
6.5 a
9.5m
c
III
0.5 •
3.5m
6.5.
9.5 .
C
III
0.5 •
11:
10.5 a
C
in
3.5 •
6.5.
10.; a
in
0.5 •
3.5.
6.5 a
8.5.
Bee.
Depth
ft
51.6
51.7
52.1
52.5
53.0
53.2
Solar
ft-c
Secchl
Use
ft
3.6
3.0
2.7
5.5
19.7
•c
•-9
*-9
4.7
*.6
10.0
10.0
9.0
8.5
8.2
10.2
10.2
9.8
9.6
12.0
11.3
11.0
10.3
Ik.O
1*.0
13.9
13.2
•c
10.0
11.0
19.5
15.5
Unfllterea Samples
•C/l
8.*7
0.59
9.07
1.42
3.46
0.97
0.66
0.52
1.61
1.18
Vol.
Snap.
SOlldl
•S/<
2.78
0.35
&
2.35
0.88
0.»5
0.*7
1.1*
O.T6
•Itrogen
aa II
37;
ra,
ME/I
Total
COD
•e/t
10.5
11.*
20.0
11.6
21.8
9.5
13.1
8.3
20.8
13.7
10J5
BOD,
DO
•8/<
15.2
1.5
15.2
13.2
11.8
1.0
12.3
11.5
12.0
0.0
12.1
11.4
10.5
10.2
10.3
1.9
10.3
13.5
8.9
10.6
8.2
2.0
11.0
7.0
8.6
8.8
1.3
8.6
7.8
Inorg.
*0.8
70.4
41.6
41.1
40.8
56.6
41.3
39-9
41.1
60.0
42.1
41.6
41.8
41.8
40.6
59.5
40.8
40.8
40.6
. 40.6
42.3
65.0
42.3
42.0
42.6
42.3
39-9
60.0
41.1
41.6
0.45 „ Mllllpore Filtered Sraples
Nitrogen as H
Ore.
683
14*
T.
963
105
867
206
791
221
1O06
267
ug/<
5790
127*1
*833
15765
7398
12960
585*
12*60
5030
172*0
5028
185*8
1KB
95
3
80
11
4
60
6
23
11
370
6
K,
US/'
3987
25
3*00
99
2161
37
2572
176
2977
27*
1790
229
Total
us/'
10555
12915
9088
15959
1D582
13126
9353
8821
177*6
819*
19050
Phosphorus
Be f
PQl
9
33
5
71
158
6
65
14
301
*58
Total
MS/'
56
52
9
85
9
165
14
78
30
318
51
Ca
•fft
5*.4
J55.1
61.0
59.0
j53.2
•46.5
56.3
43.*
Cl"
ng/i
29.0
27.3
28.6
?7.8
28.0
26.7
32.5
26.9
33.4
30.7
31.7
27.1
22.7
26.2
25.8
26.5
27.3
27.9
20.6
27.0
26.9
27.6
29.4
28.1
25.2
29.0
26.7
28. 9
rfl.3
30.4
26.3
27.5
26.9
25.8
8.0
6.2
8.3
6.3
8.4
8.3
8.1
8.P
8.1
8.0
8.3
8.1
8.3
7.7
8.3
8.3
8.3
8.3
8.1
7.8
8.1
8.1
8.1
8.1
7.9
7.5
7.9
7.8
7.8
8.1
7.7
8.1
e.i
8.1
8.0
Ali.
CsCOs
ng/J
170.2
293.2
173.2
171.2
173.2
174.3
170.2
255.8
171.2
171.2
172.2
166.1
171.2
239.9
175.3
173.2
174,3
169.1
237.8
170.2
170.2
169.1
169.1
169.1
259.6
169.1
168.1
170.2
166.1
239.9
172.2
171.2
169.1
173.2
Cond.
435
577
45?
504
521
515
1.50
624
538
*96
493
479
454
552
410
412
425
419
470
560
452
462
461
440
440
638
484
485
4B4
1.8}
462
572
575
529
506
506
R01Z: ualcn otlwnin notea blank! or iaittei indlciii no imlrili ««a«.
'Shore «a«ple eollKt«l by the riprap at the north aim at Intiin Cn*t ReMrrolr (K9I).
*Wlu*nt auplc collected at the dlacbar«e «lr at 1CB.
ca>oiaaelt fro> a norBU; 017 creek V»d oo the eart alia of IC8.
*Cre«k at the toiitheHt >l«e of ICH.
'Indian Creek located at the (ottth end of ICR.
tt*T at ICR.
•tertiary effluent from South fchoe Public Btlllty District, (BIPOD) W«ate Voter Tr»«toeirt Plant.
maiber location of permanent bouy vhere ccspoalte aaaplea orer 2**nr mre collected,
hteptb that eoapoalte aaavleB over 2*-or of (bour) atatlon Bo. 1, 2, and 3 vere collected.
^BEPUD tertiary effluent collected it the Luther Paae ptaping station.
-------
TABLE 14
MEASUREMENTS OF VERTICAL DISTRIBUTION OP WATER QUALITY
FACTORS THROUGHOUT 24 HOURS
Sampling
Date
1970
8/18
8/19
Station
1
1
1
1
1
1
1
Time
of
Sampling
1315
1700
2115
0100
0520
0915
1300
Sample
Depth
meters
0.5
3.5
6.5
9-5
12.0
0.5
3.5
6.5
9.5
12.0
0.5
3.5
6.5
9-5
12.0
0.5
3.5
6.5
9.5
12.0
0.5
3.5
6.5
9-5
12.0
0.5
3.5
6.5
9-5
12.0
0.5
3.5
6.5
9.5
12.0
Temp.
°C
21.8
21.3
20.8
20.0
19.2
22.0
21.4
20.4
20.0
19.5
22.0
21.5
21.2
19.9
19.2
21.3
21.2
20.2
19.8
19.3
21.0
21.0
20.2
19.8
19.2
21.0
20.8
20.5
20.2
19-7
21.5
21.0
20.0
20.0
19.7
PH
8.1
8.1
8.1
7-9
7.9
8.2
8.2
8.1
7.9
7-9
7-9
7-9
7-9
7.7
7.6
8.1
8.2
8.0
7.9
7-9
8.1
8.1
8.0
7.8
7.8
7.9
8.0
7-9
7.8
7-9
8.1
8.1
8.0
7-7
7.6
Alk.
as
CaCOa
mg/,0
144.9
145.0
148.0
150.6
153.8
140.4
147.8
150.4
151.2
155.6
144.5
147.1
146.3
148.8
152.3
146.9
144.7
148.5
146.6
155-7
145.8
146.1
148.8
149-5
155.6
142.9
147.1
145.8
147.1
149-9
148.8
146.9
148.5
149.6
150.1
Dissolved
Oxygen
mg/,0
6.9
6.9
6.0
4.1
0.9
7.2
6.9
5.4
2.0
0.4
7.0
6.9
6.7
2.7
0.3
7.0
7.0
4.7
1.8
0.4
6.4
6.2
4.8
2.4
0.2
6.7
6.5
5.8
5-3
2.8
6.8
7.0
5.9
2.8
0.6
Inorganic
Carbon
mg/0
34.8
34.8
35-5
37-7
38.5
33.7
35.5
36.1
37.8
38.9
36.1
36.8
36.6
37.2
38.1
35.3
34.7
37.1
36.7
38.9
35.0
35.1
37.2
37.4
38.9
35.7
35.3
36.5
36.8
37.5
35.7
35-3
35.6
37.4
37-5
94
-------
15
MONTHLY AVERAGE VALUES OF aUALITY FACTORS IH I11DIAH CREEK RESERVOIR VATEK (C) OBSERVED BY
LTAC DEMONSTRATION GRANT LABORATORY (= WEEKLY SAMPLES)
Month
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
1970
Jan
Feb .
Mar
Apr
Mey
Jun
Jul
Aug
Sep
Oct
Hov
Dec
Jan
Feb
Mar
Apr
NO. or
Samples
1
3
5
3
U
5
3
S
1
2
3
3
3
S
5
it
it
5
.1,
2
2
2
3
S
Unfiltered Samples
SS
1,1-90
7,237
1,600
!.,8l7
2,587
5,575
1,620
1,6*5
1,810
7,3*5
9,183
0.9O
2.81
3-1*2
2.01
8.65.
2.32
1.02
2.59
2.57
l.OCr
5.60
8.16
3.*6
vss
usA
61.0
4,193
1,328
3,513
1,067
1,875
750
675
530
2,750
7,377
0.62
1.25
2.62
0.91
1.02
0.87
0.52
0.86
0.55
0.59
U.lij
3.38
2-35
Org.
N
us A
360
1,002
.1,021
1,066
S,1W
822
821
1,020
733
1,077
1,373
ag.lt
8,250
3,791
3.190
3,190
3,701
S,710
2,81*0
1,'*93
8,885
2,920
3,508
Total
f
99
1*3
48
33
5?
77
70
76
68
76
35
COD
rag/r
8
33
1.0
K
17
36
18
15
20
1*5
SB
12.5
13.1
11,. 1.
13. S
U-7
18.6
15.7
11.0
15.2
17.0
17.5
0.45 u Killipare Filtered Samples
Org.
N
600
81*7
1,065
990
1,021
922
921*
1,008
723
890
1,005
1,01.7
973
1,056
896
1,057
9)8
9S9
897
663
U6o
959
71*5
925
™*
4,200
3,283
3,070
2,U*2
3,608
2,825
2,981
!*,570
3, ''SO
3,638
3,793
3,9*0
3,252
2,453
3,192
3,222
3,225
i*,o66
4,108
4,385
*,633
4,121.
5,579
6,626
JA
282
395
339
297
S68
357
122
180
110
1*6
105
102
117
162
21*9
275
313
226
178
11*0
50
5
7.5-6.0
a. 3
6.1-8.2
8.1-8.2
8.1-8.1.
7.9-8.0
8.C-8.2
7.8-6.2
8.0-8.1
8.1
8.0-6.1
8.1-8.3
Alk.
"«/
Q5
CsCC3
108.5
104.7
107.7
107.7
119.1*
133.8
1?9.1
1J1*. 5
11*0.3
126.6
129. L
132.3
135.5
126.U
130.5
1*5- E
11.2.2
133.1
1*7.8
152.1
153-1
175-8
- 170-2
170.2
10-6
vi aihos
295
508
317
3*8
361*
580
350
385
•05
386
366
-21
407
*25
*53
1*09
-85
384
ii20
1.51.
1.1?
"55
1.1,1
1.62
Inor,
C
as//
27.1
25,1
26.1
25.9
29.0
52.1
51.*
33.6
33.7
30.5
3i.o
32.6
33.*
30. *
31.3
34.9
JJ..1
3?. 7
35.9
57-3
36.8
1.2.2
1*0.8
lto.9
-------
TABLE 16
EENTHIC ORGANISM SURVEY, INDIAN CREEK RESERVOIR
Station 1
Sample Date - October 9, 1969
Organism
Cladocera
Ephippia*
Chironomidae
Tanypodinae
Procladius sp.
Chironominae
Chironomus (Chironomus) sp.
Glyptotendipes sp.
Total Organisms
Sample Volume (liters)
Sample
a
2168
35
55
90
.6
b
I960
17
kl
6k
.6
c
2360
33
119
2
15U
.6
Total
61*88
85
221
2
308
1.8
Mean
2165
28
7^
.7
103
.6
Sample Date - October 14, 1970
Cladocera
Adults*
Ephippia*
Copepoda*
Hydracarina
Chironomidae
Tanypodinae
Procladius sp.
Chironominae
Chironomus (Chironomus) sp.
Chironomus (Cryptochironomus) sp.
Glyptotendipes sp.
Tanytarsus sp.
Total Organisms
Sample Volume (liters)
6
3080
3
25
31
Ik
2
2
13^
0.9
8
2800
2
36
27
81
1
1^5
0.9
17
2^00
5
kk
^k
77
2
1
3
161
1.2
31
8280
10
105
92
232
3
3
5
1^0
3.0
10
2760
3
35
31
77
l
l
2
lUT
1.0
Station 2
Sample Date - October 9, 1969
Cladocera
Ephippia
Chironomidae
Tanypodinae
Procladius sp.
Chironominae
Chironomus (Chironomus) sp.
Glyptotendipes sp.
Total Organisms
Sample Volume (liters)
2560
80
73
2
155
1.2
2kkO
60
78
3
iia-
1.2
2280
56
88
2
1U6
1.2
7280
196
239
7
1*2
3.6
2U27
65
80
2
1^7
1.2
Not included in totals.
-------
Station 2 (Continued)
Sample Date - October l4, 1970
Organism
Cladocera
Adults*
Ephippia*
Copepoda*
Hydracarina
Chironomidae
Tanypodinae
Procladius sp.
Chironominae
Chironomus (Chironomus) sp.
Chironomus (Cryptochironomus} sp.
Glyptotendipes sp.
Tanytarsus sp.
Total Organisms
Sample Volume (liters)
Sample
a
11
1800
2
22
7
1
3
2
1
36
0.4
b
4
2100
20
14
7
l
k2
0.3
c
3
1600
3
30
9
3
1
^3
0.6
Total
18
5500
5
72
30
11
4
3
1
121
1.3
Mean
6
1833
2
24
10
4
1
1
1
40
0.4
Station 3
Sample Date - October 9, 1969
Cladocera
Ephippia*
Chironomidae
Tanypodinae
Procladius sp.
Chironominae
Chironomus ( Chironomus ) sp .
Glyptotendipes sp.
Tanytarsus sp.
Total Organisms
Sample Volume (liters)
2208
4o
30
i
71
.5
3160
80
111
1
192
.9
1760
60
74
134
• 7
7128
180
215
1
1
397
2.1
2376
60
72
.3
.3
132
,7-
Sample Date - October Ik, 1970
Cladocera
Adults*
Ephippia*
Copepoda*
Hydra carina
Chironomidae
Tanypodinae
Procladius sp.
Chironominae
Chironomus (Chironomus) sp.
Chironomus (Cryptochironomus ) sp.
Glvptotendipes sp.
Tanytarsus sp.
, Orthocladiinae
Trichocladiug sp.
Total Organisms
Sample Volume (liters) ;
13
1600
32
42
20
1
8
1
104
0.9
21 •
1900
20
34
21
1
11
87
0.9
37
1850
16
26
53.
12
3
8
102
1.2
71
5350
.16
78
129
53
.1-.
4
27 :
1
293
3.0
24
1783
5
26
43
18
1
1
9
1
98
1.0
Not included in totals.
97
-------
TABLE 16 (Continued)
Station k
Sample Date - October 9, 1969
Organism
Cladocera #
Ephippia
Chironomidae
Tanypodinae
Procladius sp.
Chironominae
Chironomus (Ghironomus) sp.
Glyptotendipes sp.
Tanytarsus sp.
Total Organisms
Sample Volume (liters)
Sample
a
I8t0
50
121
1
1
173
1.2
b
2520
41
Itl
2
1
185
1.0
c
1632
32
91
k-
1
128
.6
Total
5992
123
353
7
3
k86
2.8
Mean
1997
ti
117
2
1
162
.9
Sample Date - October it, 1970
Cladocera
Adults*
Ephippia*
Copepoda*
Hydracarina
Ephemeroptera
Siphlonurus sp.
Chironomidae
Tanypodinae
Procladius sp.
Chironominae
Chironomus (Chironomus) sp.
Chironomus ( Crypt ochironomus) sp.
Glyptotendipe s sp.
Gastropoda
Lymnaea sp.
Physa sp.
Total Organisms
Sample Volume (liters)
23
3500
3
26
1
37
12
3
2
81
0.3
5
2000
33
30
16
3
82
0.9
72
600
7
k
1
13
10
1
1
1
31
OA
100
6100
10
63
2
80
38
1
7
l
2
19*4-
1.6
33
2033
3
21
1
27
13
1
2
1
1
65
0.5
Station 5
Sample Date - October 9, 1969.
Cladocera
Ephippia*
Chironomidae
Tanypodinae
Procladius sp.
Chironominae
Chironomus (Chironomus) sp.
Glyptotendipe s sp.
Tanytarsus sp.
Unidentified pupae
Total Organisms
Sample Volume (liters)
Wo
17
3t
1
52
.6
too
13
8
8
3
32
• 9
2520
35
69
2
10
1 ..
117
.6
3^00
65
111
11
13
1
201
2.1
1133
22
37
^
1*
.3
67
.7
Not included in totals.
98
-------
Station 5 (Continued)
Sample Date - October 14, 1970
Organism
Cladocera
Adults*
Ephippia*
Copepoda*
Hydra car ina
Ephemeroptera
Siphlonurus sp.
Chironomidae
Tanypodinae
Procladius sp.
Chironominae
Chironomus (Chironomus) sp.
Glyptotendipes sp.
Tanytarsus sp.
Orthocladiinae
Trichocladius sp.
Unidentified pupae
Gastropoda
Physa sp.
Total Organisms
Sample Volume (liters)
Sample
a
6
1420
5
2
3
10
3
2
20
0.4
b
16
2310
16
5
12
8
7
1
1
50
0.3
c
2
2140
8
12
2
20
6
5
1
3
1
1
51
0.6
Total
24
5870
13
30
7
35
24
15
2
5
1
2
121
1.3
Mean
8
1957
4
10
2
12
8
5
1
2
1
1
4o
0.6
Station 6
Sample Date - October 9, 1969
Cladocera
Ephippia*
Chironomidae
Tanypodinae
Procladius sp.
Chironominae
Chironomus (Chironomus) sp.
Glyptotendipe s sp.
Tanytarsus sp.
Unidentified pupae
Total Organisms
Sample Volume (liters)
6l6
^5
20
5
20
1
91
.6
Not included in totals.
99
-------
TABLE 16 (Continued)
Station 6 (Continued)
Sample Date - October 14, 1970
Organism
Cladocera
Adults*
Ephippia*
Hydra carina
Chironomidae
Tanypodinae
Procladius sp.
Chironominae
Chironomus (Chironomus) sp.
Tanytarsus sp.
Gastropoda
Lymnaea sp.
Total Organisms
Sample Volume (liters)
Sample
a
2
3^0
1
2k
5
1
1
30
0.5
b
c
Total
Mean
Station 7
Sample Date - October 9, 1969
Cladocera
Ephippia*
Chironomidae
Tanypodinae
Procladius sp.
Chironominae
Chironomus (Chironomus) sp.
Chironomus (Cryptochironomus) sp.
Glyptotendipe s sp.
Tanytarsus sp.
Total Organisms
Sample Volume (liters)
26UO
26
7
1
5
5
l*
1.2
Station 8
Sample Date - October 9, 1969
Chironomidae (midges)
Orthocladiinae
Cricotopus sp.
Trichocladius sp.
Chironominae
Glyptotendipe s sp.
Phy s idae (snails)
Physa sp. •
Total Organisms
139
16
895
2
1052
Not included in totals.
100
-------
TABLE 16 (Continued)
Station 8 (Continued)
Sample Date - October Ik, 1970
Organism
Hirudinea
C la doc era
Adults*
Copepoda*
Amphipoda
Hyalella sp.
Ephemeroptera
Baetis sp.
Coleoptera
Dytiscidae
Deronectes sp.
Elmidae
Optioservus sp.
Chironomidae
Chironominae
Glyptotendipes sp.
Orthocladiinae
Cricotopus sp.
Nanocladius sp.
Trichocladius sp.
Unidentified pupae
Gastropoda
Gryaulus sp.
Helisoma sp.
Limnaea sp.
Physa sp.
Total Organisms
Sample
a
10
9
8
8?
2
1
2
78
39
9
11
2
101
20
225
7^
661
la
c
Total
Mean
Not included in totals.
101
-------
TABLE 16 (Continued)
Station 9
Sample Date - October 9, 19^9
Organism
Ephemeroptera (mayflies)
Siphlonuridae
Slphlonurus sp.
Hemiptera (true bug s )
Cortxidae (water boatmen)
Sigara sp.
Callicorlxa sp.
Notonectidae (backswimmers)
Notonecta sp.
Coleoptera (beetles)
Dytiscidae (predaceous diving
beetles)
Agabus sp.
Laccodytes sp.
Diptera (flies)
Chironomidae
Orthocladiinae
Gricotopus sp.
Nanocladius sp.
Chironominae
Microtendipes sp.
Glyptotendipes sp.
Total Organisms
Sample
a
25
2
k
2
1
1
332
69^
58
2k
n43
b
c
Total
Mean .
102
-------
TABLE 16 (Continued)
Station 9 (Continued)
Sample Date - October ±h, 1970
Organism
Nematoda (roundworms)
Oligochaeta (segmented roundworms)
Hydracarina (water mites)
Ephemeroptera (mayflies)
Baetidae
Baetis sp.
Trichoptera (caddisflies)
Hydropsychidae
Hydropsyche sp.
Parapsyche sp.
Zygoptera (dragonflies )
Coenagrionidae
Argia sp.
Hemiptera (true bugs)
Corixidae (water boatmen)
Sigara sp.
Coleoptera (beetles)
Dytiscidae (predaceous diving
beetles)
Agabus sp.
Laccodytes sp.
Laccophilus sp.
Hydrophilidae (water scavenger
beetles)
Tropisternus sp.
Elmidae (riffle beetles)
Optioservus sp.
Diptera (flies)
Chironomidae (true midges)
Tanypodinae
Conchapelopia sp.
Procladius sp.
Chironominae
Glyptotendipes sp.
Micropsectra sp.
Paralauterborniella sp.
Pseudochironomus sp.
Orthocladiinae
Cricotopus sp.
Corynoneura sp.
Nanocladius sp.
Unidentified pupae
Tabanidae (horse flies)
Empididae (dance flies)
Total enumerated
Ira ct ion of sample enumerated
Computed total in sample
, Number of field screenings
Stream area sampled in sq ft
Number of organisms per sq. ft
Sample
a
1
1793
8
95
272
2
1
1
12
116
2
5
3
12
k
5
18
1
1
9
14
172
•- 10
1
1
2559
1/8
20^72
: 3
12
jf
1706
b
c
Total
Mean
103
-------
TfcBLB 17
MAXIMUM, HIHIHUM, AND AVERAGE VALUES OF ftUALITI FACTORS IB RECLAMED WATER
(COMPUTED FROM MONTHLY REPORTS BY THE SOUTH TAHOE PUBLIC UTILITY DISTRICT)
(All values In ng/f except Turbidity, pH, and Collform)
Date
1968
Apr
May
Jun
Jul
Aug
Sep
Get
Nov
Dec
1222
Jen
Feb
Kar
Apr
BOD5
t.8
.5
1.8
3.5
0.5
ii2
6.7
O.It
U.2
7.8C
.01
u.oa
1.5
.1
0.6
I.1*
0.0
0.6
3.2
0.1
1.0
1.8
0.0
0.7
0.8a
0.0
O.li
3.1
0.2
1.6
-
1.6
1-7
0.5
1.1
1.1
0.0
0.5
COD
22.0
7.7
i5J
19
5
±£
17.0
3-6
8.6
18.1
2.1
12.5
17.3
7-9
13.0
13.3
"*-5
2-0
18.7
5.0
12.5
25.3
7-0
It .8
13. ^
2.3
LI
18.6
3.S
W.l
21.. 8
3-7
10.9
16.J
3.2
2ii
10.9
3.1
5.B
Suspended
Solids
11
1
3
5
0
1
It
0
1
7-0
0.5
tl
3.0
o.o
0
£.0
0.0
O.jt
1.0
0.0
0.0
8.0
0.0
0.7
-
-
-
-
-
-
-
-
-
-
-
*
.
-
NBAS
.06
.01
.02
.28
O
.12
.21*
.10
.15
.20
.09
.114
.19
.IS
.16
O.193
O.08
O.lU
-
0.09
0.26a
0.09
0.15
0.15s
0.1C
0.18
0.35s
0.10
0.19
0.23a
O.ll
0.18
0.2Oa
0.01
0.12
0.1}a
O.Oo
0.09
Turbidity
JOT
2.0
.5
1.2
1.3
0.2
.6
1.0
0.2
,1.
1.0
0.1
00
0.3
0.1
O.g
O."t
0.1
0,1
1.9
0.1
0.7
2.9
0.5
l.it
1.7
0.5
P^2
6.2
0.8
2.1
l.lt
0.2
0.8
0.9
0.1
2il
0.7
0.1
0.2
pH
9.0
7.6
lil
7.9
6.6
7.2
8.2
b.9
7-1*
8.1
7.0
LI
8.U
7.0
LI
7.7
6.8
'Li
a. 8
6.8
L2
9.1
b.9
8.1
7.8
6.5
b-i
8.9
6.1t
6.2
7-2
6.1
6.8
8.5
6.6
M
8.5
6.6
7.6
Chlorine
Residual
Instantaneous
3.9
0.1
2.1*
O
0.9
S.I
8.0
,u
a. it
4.J
1.0
2il
6.6
1.6
il
l1*. 7
1.6
5.8
21.1.
0.0
iii
9-9
0.0
M
3.3
0.0
2.1
3.1
o.o
1.6
"t-5
0.0
2.3
7.6
0.8
3.0
5-3
0.6
2.3
Coliform
(mpn)
9-2
2.2
2.7
16.0
2.2
5^°
5.1
2.2
2_A
16.0
z.s
6._6
16.0
2.2
M
16.0
2.2
2.8
16.0
2.2
6.0
2.2
2.2
2.2
5.1
S.2
a.>t-
5.1
2.S
2.2
16.0
2.2
M
5.1
2.2
a.i>
2.2
2.2
2.2
nitrogen
Organic
Oa
0
0
oa
0
0
_
-
-
-
-
-
_
-
-
-
-
-
-
-
-
-
-
-
-
-
-
.
_
-
-
-
-
_
-
-
.
-
Ammonia
27"
20
Si
18. 6"
0
14.7
i3.ea
.12
5^57
13.6s
6.3
fcS
8.5a
7-9
6.2
9.3"
0.5
iL.l
so.o8
6.8
13.8
-
^_-2
_
_
-
e
_
iil
-
_
-
_
-
-
_
-
"
Nitrate
0.6s
.01
.18
12.0"
0.1
6.8
12. 3a
t.5
8.0.
9.6"
1.8
5^8
7.2s
5.8
60
e.oa
2.5
6.0
0.1»a
0.0
0.16
o.6oa
0.00
0.23
0.6J
0.00
0.17
o.ua8
0.00
0.22
O.'tO
0.00
0.11
0.60
0.00
0.30
2.70
0.63
1.25
Nitrite
_
.
-
5-7°
o.i>
2.2
0.8a
0.6
T
3.5a
1.6
g.2
3.9a
0.7
2.7
1.3s
1.3
kl
O.U8a
0.08
0.28
0.92a
0.01
0.17
0.29
0.00
0.03
0.15
0.01
O.Olt
O.llt
o.oo
0.03
0.1*7
0.00
°4i3
0.78
0.01
0.33
Phosphate
0.70
O.Olt
0.58
2.7O
.03
l^J.i*
1.6
0.2
3.
1.8
O.I.
1^2
1.20
O.OS
Ji5
o.ao
o.co
.15
o.6Ua
0.07
O.J5
U.90a
0.06
iiS
0.52
0.01
0.20
0.5"t
0.01
0.18
0.^9
0.03
p_._17
0.51
0.10
o.su
o.itg
O.OJ
0.25
ALkslinlty
£73"
229
£5°
;>oa
1-5
. — j
2-6=
lo^
laa
2^2
157
su
SC-i
-73
;a6
259
£C'5
£52
;oo
212
11:2
£50
42
166
-27
197
260
3LQ
- 66
iil
516
150
2^jt
;19
131
£39
:-r3
1U2
215
Hardness
a
_
igo
iei.a
1.50
l^D
I6oa
li-0
151
lbla
1J-
1 =_^
lS6a
112
1=2
' -^s
122
IrO
:56S
112
123
i£o
72
125
200
ill
260
30-
1.8
1=8
178
51*
130
2Co
5-1-
136
170
70
1U5
Totol
Dissolved
Solids
2«8B
192
220
360"
328
Jllit
3«a
291*
322
J^2a
179
271
576a
190
275
It 12"
295
366
382s
2k&
3J2
306s
298
505
_
.
-
_
-
_
_
-
_
_
-
_
_
"
Chloride
55"
J.
2^
37"
15
30
33a
25
2£
63. 8a
21. J
3il
39a
jl
31
32a
23
3i
39.0s
30.0
3M
39
19
28
31*
lit
26
kg
12
li
31
20
2jt
32
23
i§
35
15
22
Sulfate
-
258
Zk
22
26a
23
25
52. Oa
22.8
32.2
2fla
2
16
30a
2i*
26
23°
28
28
><5
1}
21
35
15
25
36
10
22
60
18
Jl
i»8
1U
28
26
15
i2
< 2.2 Is minimum value detected.
-------
TABI£ 17 (Continued)
Date
1969
Cont,
May
Jul
Aug
Sep
Oct
Nov
Dec
1970
Jan
feb
Mar
Apr
BOD
1.0
0.1
U.I
0.2
1.2
1.8"
O.U
OJ3
U.g"
0.2
ti
3.8
0.2
1.2
l.U"
0.1
O.J.
3.9"
o.u
1.8
6.7°
0.2
2.U»
0 2
0.7
5-0"
0-5
U.5
0.7
2.3
5.0"
0.8
COD
L2-7
10.6
3.8
7.2
lfl.9
3-5
11.1
16.2
3.2
Si
1U.2
0.9
8.1
12.8
0.6
21.7
1-7
8.7 •
2U.O
2.9
9.8
18.1
1 1
7.5
20.7
2.U
8.9
30-7
3.U
1U.3
18.3
U.5
Suspended
Solids
-
-
-
-
-
.
-
-
-
0
0
0
0
0
0
0
0
0
-
-
0.0
0.0
o.o
0.0
o.o
o.o
0.0
0.0
0.0
MBAS
0.27s
0.10
O.lU
o.oo
0.09
0.07
0.16
0.27"
0.01
0.13
O.lU"
0.00
0.07
0.20°
0.01
0.12
0.35°
0.08
0.22
O.l8a
0.00
0.07
0.09"
0.07
0.08
0.1U°
0.10
0.12
0.55°
o.u
0,27
0.35"
O.lU
0.27
Turbidity
1.2
0.2
1.0
O.i
0.3
1.0
0.1
o.u
0.8
0.1
0^3
O.U
0.1
0.2
0.8
0.1
0.2
1-3
0.3
0-1
1.5
0.3
0.6
1.8
0.3
0.7
0.6
0.2
o.u
1.1
0.3
0.6
1.0
0.3
0.5
pH
8.1
6.8
Li
8.8
6.7
Li
9A
6.6
L5
8.1
6.5
Li
6.8
L°
8.1
6.7
Li
8.7
6.6
Li
8.3
6.6
Li
8.U
6.8
7.0
8.2
7.1
7.7
8,1
6-5
7.2
7.8
6.8
Chlorine
Residual
Insta ntaneous
U.O
0.5
l.U
2,7
O.U
0.2
3.0
o.u
kl
3 8
0.6
1.5
2.8
0.2
1.9
3.7
1.2
2-U
6.0
0.9
3.0
U.7
0.7
6.0
O.U
3-1
6.6
0.7
2.2
0.0
1.5
6.1
0.7
2.5
Coliform
(mpn)
2.2
2.2
2.2
l6.0
2.2
3.0
5.1
2.2
2.5
5.1
2.2
2^1
2.2
2.2
2.2
8.8
2.0
2.2
2.2
2.0
2.0
5.0
2.0
2.1
2.2
2.0
2.0
2.0
2.0
2.0
38.0
2.0
3.U
2U.O
2.0
2.7
Nitrogen
Organic
-
-
,
_
-
-
-
„
-
-
-
-
,
.
-
-
-
_
-
-
.
.
•
Ammonia
-
-
15.3
11.5
11.1
i£ri
a
.
iSil
17.9s
10.7
11*. 2
19.8
10.9
15^2
ss. u
6.0
17.1
27.1
13.0
25.6
6.6
16. U
25. U
16.8
19.8
23-9
13-3
19.7
31.1
13.9
20.9
Nitrate
1.75
0.00
9^12
U.Uo
0.00
0.90
6.70
0.38
2-UJ.
7.8
0.0
2.2
3.5
0.0
1.1
2.U
0.1
1.1
3.9
0.0
1.1
1.2
0.0
1.1
0.0
o_.6
1.3
0.0
o.u
o.u
0.0
0.2
0.3
0.0
0.1
Nitrite
0.58
0.01
0.10
1.25
0.00
0.19
5.50
0.09
2. UP
2.80
0.00
0.26
1.98
0.02
O.J2
1.58
0.01
o.a6
0.36
0.01
0.12
0.23
0.00
0.06
0.58
0.00
0.12
0.05
0.00
0.03
O.U8
o.oo
0.16
1.00
0.00
0.11
phosphate
C.7C
C.07
C^2g
C.J7
C . "£
C.2C
C.CO
i-iS
C.2C
O.OC
C.12
C.CC
C.Cy
-•£?
C.C1
C.I;
*- •£ '
c.oo
C^Cv
2 .56
C.17
C."5
;.cc
O.E£
C.-J
c.09
0.20
0.63
O.&l
0.1?
O.OC
O.C7
.Alkalinity
272
137
£ii
252
1U9
206
102
m
2U7
178
21U
250
120
200
U30
21U
27C
290
175
2,50
293
156
215
233
159
19U
255
135
211
279
180
227
270
182
218
Hardness
170
80
135
156
7U
120
166
38
110
15"t
120
lUl
118
LU4
176
108
iU2
170
13U
15_U
178
llU
150
166
106
iis
178
106
156
18U
102
15f
176
132
15U
Total
Dissolved
Solids
:
-
-
-
-
^
-
-
-
"*
a
3JQ
ujg
170
M
520
152
25i
390
220
• 320"
280
303
}00a
JOO
300
260"
260
260
-
Chloride
33
Ifl
22
25
11
iL
30
17
22
28
17
2U.
60
17
26
28°
2O
23
22
26
2fla
21
22
3?"
15
23
25"
18
22
29"
22
25.
32s
£5
28
Sulfate
38
15
22
28
15
ii
US
17
27.
56
15
S
56
18
22
29
12
21
56°
33
52fl
30
31
36a
19
27
31a
16
20
17
21
19
36
-------
TABLE 17 (Continued)
Bate
May
Jun
Ju
Aug
Sep
Oct
gov
Dec
1971
Jan
Feb
Mar
Apr
1
BODs
4.8a
1.0
3.5
8.9
1.0
2.0
*.3
0.1
1,4
3.1
O.I
1.0
a.6
0.2
1.0
1.7
0.3
1.0
i-7
O.I
o.J)
2.1
0.2
1.2
7.9
.0
_._§
.1
.1
-25
8.8
0.0
0.8
1.2
0.2
0.8
1
COD
82.7
7.6
"i?
84.5
0.8
12.3.
S6.7
9.4
J5.Z
20.O
5.1
10.8
12.5
3.9
_2ii
tl
Ji2
14.1
2.0
7.Q
26.0
3.<»
13-5
38.0
8.0
16.5
1.1
7.3
1£J
HA
4.8
8.8
14.1
8.6
8>
Suspended
Solids
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0,0
0.0
0.0
o.o
0.0
0.0
0.0
0.0
o.o
o.o
0.0
0.0
o.o
0.0
o.o
0.0
o.o
0.0
5.5
0.0
i2
10.0
0.0
5.7
0.0
0.0
0.0
1
DBAS
0.46
0.18
0.32
0.46
0.19
0.34
O.lfO
0.08
0.28
0.28
0.05
O.L5
0.25
0.13
0.19
0.17
0.06
0.13
0.23
0.05
0.12
0.52
0.07
0.29
0.61
0.15
0.30
0.1,3
0.17
0.30
0.19
0.01
0.12
0.8l>
O.O6
0.14
Turb'idit
JTU
1.0
0.3
0.4
8.0
0.4
M
1.0
0.8
0.5
0.4
0.1
0.3.
0.3
0.1
0.2
0.2
0.1
0.2
0.6
0.2
0.2
0.7
0.1
0.4
0.4
0.1
0.3
0.6
0.2
0.3
0.6
0.2
0.3
0.5
0.8
0.3.
pH
8.3
6.7
7^-1
7.9
6.8
7_±1
8.9
7.1
7.6
8.3
6.8
7^5
8.3
6.8
7A
7.6
6.9
Li
8.1
6.9
ZJ
7.7
6.9
7.U
7.*
6.8
7-5
6.8
7.5
6.8
7.5
7.1
Color ine
Residual
Instantaneous
3.6
0.0
?i5
6.3
0.0
LI
5-5
0.6
8.4
4.3
0.0
ii§
U.I
1.9
i°
3.1
0.8
1.6
8.0
0.8
iil
2.2
0.9
±J_
2.7
0.9
ij:
2.8
0.7
3.5
1.3
2.1
4.4
l.U
S3.
CollfOZlD
(npn)
8.0
2.0
8.0
5.0
8.0
2.2
8.0
2.0
8.0
8.0
8.0
2.0
8.8
8.0
8.2
15.0
2.0
i£
2.0
8.0
g.g
38.0
S.O
i5
8.2
2.0
2.0
< 2.0
<2.0
< 2.0
< 2.0
< 8.0
< 8.0
< 8.0
< 2.0
< 8.0
Nitrogen
Organic
-
-
-
-
-
-
-
-
-
-
-
.
Asconia
18.9
13.3
16.5
21.1
13.8
18.1
26.2
18.8
£1.8
81.8
15.1
19.0
19.8
12.6
16.5
19.7
13.3
16.8
25.9
11.7
19.2
28.2
15.9
£1.4
;?.4
1--9
Jili
£i.6
18.1
£1.9
27.0
15.6
20.4
21.9
11.8
17.9
Nitrate
1.4
O.O
0.8
0.8
0.0
0.0
0.6
0.0
0.2
1.8
0.1
0.8
8.6
0.0
ii
1.3
0.1
0-7
1.4
0.1
0.9
0.9
0.0
0.4
0-3
0.0
0.1
o.4
0.0
0.2
2.3
0.0
0.8
0.4
O.O
0.8
Nitrite
0.15
o.oo
0.04
0.07
0.00
0.03
0.35
0.00
0.06
0.46
0.01
0.17
0.52
0.04
0.34
0.34
0.02
0.13
0.34
0.08
0.14
1.01
0.01
0.03
0.68
o.oo
0.06
O.20
o.oo
0.02
0.02
0.00
O.O1
0.18
O.O1
O.C4
Phosphate
0.30
0.01
0.09
0.61
0.03
0.19
0.75
0.06
0.38
0.65
0.06
O.89
O.2O
0.00
0.07
0.39
O.OO
0.06
1.04
0.01
0.14
0.20
0.08
O.10
0.42
0.03
0.09
0.13
0.02
0.07
0.35
0.06
0.14
0.17
0.03
O.09
Alkalinity
325
198
827
830
Ifll
200
275
1U5
2J2
315
176
848
877
196
251
296
195
853
183
325
259
385
218
ail
287
199
S5J.
296
807
268
307
172
836
244
169
203
Hardness
182
132
161
200
ISO
143
150
74
121
800
126
156
150
114
155
196
116
144
346
102
157
814
128
165
19S
118
161
80S
104
166
214
136
164
164
186
147
Total
Dissolved
Solids
-
-
-
388"
272
2%.
260&
260
860
44oa
304
558
370
246
335
344"
870
305
400
186
287
450
180
867
330
120
881
310
200
269
Chloride
43a
85
Jl
32"
23
£L
32s
24
28
38"
84
27
43"
86
30
38"
24
89
36"
28
87
51s
22
30
31"
19
25
37s
84
26
25°
19
28
25"
18
88
Sulfate
45'
36
40
56s
41
47.
58s
19
J2_
55"
19
38
58"
22
3U
48"
2
33a
28
86
56"
10
32
588
80
22.
40s
83
27
26a
18
24
29*
16
22
o
o\
*Fever than tea observations Bade during nonth.
-------
TABLE 18
MAXIMUM GF.CV.TH RATES AND CELL CONCENTRATIONS ATTAINED IN FIVE-DAY FLASK ASSAYS OF
rr, BTOUNDED, AND DISCHARGED WATER AT INDIAN CREEK RESERVOIR
Date
1968
10- 3a
11- 4
4- 1
4-28
5-29
6- 4
6-19
6-24
Sample
ICR A
ICR B
ICR A
ICR B
ICR A
ICR B
ICR A
ICR B
ICB A
ICR B
ICR C
L-III
:CR B
ICR C
L-III
ICR B
ICR C
L-III
IRC B
UC C
L-III
Cone.
50
50
50
100
50
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
^
.713
,6l4
.656
.531
.696
.64g
.307
.544
.729
.288
.457
.683
.304
.355
.571
.515
.277
.386
.099
.372
.638
.168
.388
.609
.187
.529
.850
.153
.499
.157
.270
.567
.727
.250
.194
.253
.321
.640
.168
.588
.499
.779
.299
.347
.298
.287
.224
.082
.096
.298
.521
.096
.242
.274
.120
.359
.058
Corr.
Coef.
.988
.982
.994
.968
.971
• 973
.914
-938
.986
.985
.943
-991
.958
.905
.943
.861
.946
.971
.742
.953
.975
.875
• 952
.922
.901
.9^5
.988
.904
.929
.826
.847
.963
.997
.913
.824
.949
.934
.972
.744
.845
.962
.988
.894
.880
.879
.937
.864
.710
.657
.835
.985
.693
.884
.875
.729
.945
.521
*,
.8610
.7642
.7533
.6951
.9022
.8158
.4814
.8530
.8826
.3362
.6628
.7817
.3569
.6036
.5^99
.5832
.3772
.-+426
.2079
.4611
.7392
.2402
.5357
.7579
.2517
.8086
1.0496
.2331
.7774
.2869
.3728
.8133
.8068
.3782
.2697
.3398
.4841
.7802
.2979
.6560
.6998
.8996
.5190
.6439
.5545
.3790
.1568
.2240
.4306
.6181
.1665
.4246
.5027
.2277
.4511
.1272
?
6.5
10.7
8.1
15.1
15.9
21.1
16.7
7.4
12.0
7.3
14.0
14.4
12.0
10.5
9.7
20.0
4o.5
21.4
31.0
22.4
12.4
36.5
21.9
24.2
31.6
13.3
5.9
26.3
10.0
33.2
36.7
17.3
5.7
29.3
18.8
14.7
19.9
20.6
45.8
26.6
19.5
5.7
17.9
15.9
10.4
26.5
20.8
70.6
47.9
15.0
20.0
52.6
24.3
19.4
39.9
20.8
57.5
^
744.
»*35.
480.
265.
532.
445.
151.
345.
659.
122.
222.
643.
210.
203.
216.
180.
235.6
324
60'.
148.
467.
71.
153.
405.
83.
237.
1061.
76.
246.
6l.
96.
229.
552.
85.
70.
93.
98.
312.
32.
127.
263.
862.
128.
149.
129.
126.
88.
41.
87.
220.
544. .
90.
160.
164.
90.
209.
51.
s-
17.5
20.4
12.4
8.8
29.8
25.6
9.1
23.0
14. 9
9.1
18.6
5.9
21.0
22.5
21.1
22,3
7.2
16.1
6.2
10.0
19.6
18.3
20.5
52.4
29.2
10.9
9.3
12.2
25.4
12.3
21.8
2.8
7.4
4.4
8.9
15.2
14.2
35.6
10.0
4.6
11.7
21.7
15.5
14.2
17.8
12.5
15.6
17.3
29.4
54.0
10.9
23.4
11.9
10.4
18 .-6
34.3
14.7
ss
24.25
11.64
16.28
23.44
19.68
24.31
6.06
15.71
30.00
5.06
10.41
23.43
7-15
8.29
9.40
7.37
9.44
13.75
2.31
5.88
20.67
2.70
7.24
21.09
3.28
7-57
28.59
3.76
10.74
5.86
4.34
8.70
17.68
3.06
3.42
3.38
4.28
11.81
3.22
3.80
8.79
27.30
4.22
5.56
6.29
4.31
i*!l8
3.08
4.41
10.17
15.33
4.45
6.14
7.10
4.68
10.48
3.32
107
-------
TABLE 18 (Continued)
Date
7- 1
•7 • - C
7-T~
_._,-
~.:c
S- -
8-L£
Sample
ICR B
ICR C
L-III
ICR B
ICR C
L-III
ICR B
ICR C
L-III
ICR B
ICR C
L-III
ICR B
ICR C
L-III
ICR E
ICR C
L-III
ICR B
ICR C
L-III
Cone.
*
1
10
100
1
10
100
1
10
100
1
10
100
1
10
IOC
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
%<
.094
.044
.069
.082
.042
.181
.020
.116
.011
.155
.287
.482
.121
.090
.061
.113
.204
.030
.130
.208
.240
.107
.104
.153
.251
.429
.114
.376
.657
.421*
.387
.609
.106
.493
.258
-.020
.082
.315
.603
.081
.062
.212
.078
.092
.037
.222
.521
.672
.161
.210
.286
.196
.007
.036
.189
.541
.711
.067
.091
.094
.105
.299
-.028
Corr.
Coef .
.647
.638
.702
.778
.434
.906
.243
.616
.119
.954
.957
.993
.982
• 9"*5
.271
.963
.912
.607
.929
.981
.461
.961
.966
• 930
.951
.936
.959
.942
.982
.973
• 937
.966
.869
.972
.951
-.600
.918
.980
.973
• 931
.910
.9W
.970
.890
.820
.914
.985
.984
.962
.976
.852
.9^5
.274
.5^
.954
.985
.975
.829
.842
.799
.923
.979
-.485
^
%
.1802
.1058
.1388
.148.1
.1221
.2651
.1093
.3305
.0941
.1862
.4279
.4936
.1321
.1349
.0704
.1390
.3130
.0484
.1667
.2697
.5757
.1479
.1317
.2523
.3899
.6966
.1337
.5861
.8418
.5774
.6323
.8484
.1884
.6646
.3981
.0069
.1261
.4234
.8281
.1180
.0858
.3243
.1001
.1163
.0619
.3435
.6735
.8624
.2323
.2812
.4i66
.3073
.0334
.0919
.2848
.6953
.9658
.15^3
.1908
.2076
.1614
.3905
.0447
I"
78.1
27.8
35-0
49.4
58.1
27.6
91.4
47.6
113.6
5.5
14.1
3.2
6.7
13.6
41.9
17.1
17-0
40.5
3D.5
3.9
42.7
17.8
11.1
5.9
4.7
3.9
33.2
13.0
8.2
5.4
6.0
14.5
9.0
10.2
70
156.5
21.8
5.1
4.6
39.8
24.1
8.1
14.3
32.9
44.3
14.9
3.3
4.4
10.2
2.7
43.3
5.4
38.9
26.7
5.1
4.2
3.6
22.3
9.5
15.0
5.9
6.5
92.4
X5
66.
63.
75.
71.
68.
115.
65.
67.
52.
228.4
396.3
773.8
205.8
187.
111.2
218.6
304.8
118.
257-3
364.6
693.4
239.7
241.6
332.
454.
826.8
172.4
272.7
842.2
339.2
278.6
646.8
95.7
444.2
175.
57.6
169.7
357.2
1262.4
160.7
157.8
250.
151.4
128.6
101.7
130.4
414.
759.
99.
121.8
177.9
114.6
51.5
58.2
1"*3.3
523.8
1019.6
83.3
92.2
80.8
92.8
201.4
48.8
»•
17.7
9-5
13.3
12.7
13.1
19.7
9.1
3.4
17.7
9-7
3.2
13.3
3.8
2.0
31.5
2.9
17.0
10.2
16.9
4.3
44.9
«*.3
4.1
4.0'
2.3
10.9
9.8
9.7
14.0
11.9
2.9
10.1
7.3
15.6
5.4
3.5
4.8
2.4
12.7
2.1
2.1
5.1*
3.2
10.4
2.7
6.1
2.1
8.8
3.2
4.6
4.3
3.1
3.9
13.9
4.8
8.2
16.7
1.8
2.8
5.7
8.9
3.0
3.1
ss
m/t
2.21
2.67
5.67
2.58
3.52
7.19
2.68
4.34
4.6o
5.43
11.21
24.79
5.42
6.05
3.67
7.05
9.24
3.75
6.45
10.78
56.00
6.53
7.4l
9.89
11.16
17.32
7.33
4.61
11.96
8.49
4.40
12.61
3.53
6.00
3.19
1.07
3.47
10.05
^.^
3.29
2.92
9.26
2.21
1.27
1.87
3.83
8.98
14.25
3.24
3.13
4.62
2.82
0.44
0.98
-
10.00
25.71
3.03
4.44
3.02
3.08
3.92
1.95
108
-------
TABLE 18 (Continued)
Date
8-19
9- 2
9-10c
9-16
9-25
10- 2
10-16
Sample
ICR B
ICR C
L-III
ICR B
ICR C
L-III
ICR B
ICR C
L-III
ICR B
ICR C
L-III
ICR B
ICR C
L-III
ICR B
ICR C
L-III
ICR B
ICR C
L-III
Cone.
%
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
^
.187
.572
.977
.102
.115
.091*
.152
.375
.010
.218
.246
.252
.253
.137
.153
.231
.181*
.101
.169
.377
.572
.116
.331
.249
.313
.280
-.026
.296
.227
.981
.265
.592
1.007
.390
.138
.056
.149
.615
1.182
.087
.310
1.199
.345
.544
.041
.048
.302
1.249
.062
.201*
1.092
.483
.278
-.126
.066
.180
.261
.086
.112
.209
.095
.097
-.043
Corr.
Coef.
.726
.952
.982
.633
.806
.735
.938
.939
.161
.920
.929
.942
.954
.568
• 911
.926
.821
.811
.631
.956
.982
.707
.912
.585
.831
.830
-.176
.810
.668
.947
.780
.924
.957
.803
.642
.456
.577
.853
.929
.410
.633
.962
.816
.913
.415
.492
.728
.987
.425
.795
.995
.928
.619
-.824
.776
.898
.806
.745
.716
.711
.713
.756
-.132
A
"b
.3853
.8208
1.2644
.2571
.2224
.1905
.2215
.4653
.0751
.3576
.3859
• 2899
.3367
.1795
.1988
.3685
.2306
.1959
.3584
.5421
.7066
.2222
.4154
.8251
.5723
.5440
.0692
.5862
.5710
1.4498
.6024
.9643
1.5081
.7523
.3784
.0927
.1712
.8450
1.9552
.1554
.5968
1.7778
.7402
.9124
.1013
.1539
.4875
1.5265
.1888
.3554
1.2168
.8061
.4344
-.0234
.1210
.3237
.5838
.2069
.2810
.5511
.2523
.1740
.5135
$•
56.2
19.3
12.1
59.9
36.5
35.2
26.6
27.9
73.6
14.2
16."
15-1
18.0
51.3
43.5
23.3
53.5
29.-
36.1
12.4
16.2
56.4
31.3
11.2
32. S
13.?
15. c
26.8
8.2
18.7
14.6
12.8
9.4
26.4
33.9
121.7
99.3
35.5
5.6
103.2
47.8
3.7
8.0
11.4
44.1
37.4
37.0
8.6
23.3
31.5
7.7
7.3
76.3
-225.6
69.0
12.8
7.7
4.3
23.1
11.4
8.0
24.4
9.7
/\
xs
167.5
773.6
5455.
117.7
128.8
120.6
152.6
410.5
80.3
112.9
142.3
430.2
180.8
187.3
291.6
146.2
150.2
71.
160.5
318.6
699.6
119.
277.7
168.
266.6
195.
66.6
239.4
164.7
449.2
210.
713.
3906.
356.5
128.8
94.9
147.5
896.
6988.
101.1
243.
589.4
308.6
613.2
62.8
66.1
162.2
5720.
65.0
95.0
349.4
326.9
153.2
27.2
134.3
169.4
176.9
142.
170.6
154.5
145.3
66.
35.6
S'
20.4
21.8
6.9
11.4
8.1
14.2
6.9
34.2
10.5
11.7
9.0
21.8
10.4
36.4
8.7
5.3
25.3
7.0
49.0
17.0
11.5
21.3
36.9
16.0
30.2
30.6
33.2
28.1
53.6
1&.9
22.1
23.3
4.4
35.0
14.9
27.6
45.6
80.5
5.5
38.2
60.2
6.8
19.9
24.7
26.9
5.9
42.4
7.7
7.2
31.8
6.2
12.1
64.4
14.0
4.8
4.1
8.2
6.1
2.6
8.8
3.0
20.5
7.3
ss
ng/l
0.92
2.72
15.37
1.30
3.37
7.97
2.06
1.47
0.4i
3.28
3.82
34.10
2.07
4.50
25.56
3.95
1.38
0.15
1.29
5.71
42.11
1.66
4.51
41.32
3.13
4.98
2.04
7.48
4.83
28.48
2.86
4.94
24.33
3.61
2.49
1.73
4.32
6.86
35. ?0
3.61
6.19
26.81
5.36
4.85
0.64
109
-------
TABLE 18 (Continued)
Date
10-16
10-24
10-30
11-1}
11-19
11-26
12- 3
Sample
ICR B
ICR C
L-III
ICR B
1C? C
L-III
ICR B
ICR C
L-III
ICE B
ICE C
L-III
ICE E
ICE C
L-III
ICH B
• ICE C
L-III
ICE B
ICR C
L-III
3onc •
i
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
IX
1
10
-X
1
10
100
1
10
100
1
10
100
1
10
100
1
1C
100
1
10
100
1
1C
100
1
10
100
1
10
100
1
10
100
1
10
100 •
1
10
100
^b<
.525
.743
1.072
.525
.686
1.028
.623
.496
-.013
.303
.263
.C57
.573
.259
.170
.251
.271
.155
.C28
.139
.107
.069
.239
.385
.078
.144
-.016
.152
.179
.516
.118
.196
.1*74
.120
.108
.089
.131
.150
.608
.014
.216
.596
.108
.135
.144
.176
.168
.481
.126
.166
.557
.156
.196
.067
.115
.201
.525
.096
.186
.755
.171
.235
.900
Corr.
Coef.
.827
.902
.948
.915
.921
.981
.917
.941
-.151
.812
.903
.570
.957
.937
.917
-905
.899
.773
.481
.9^5'
.802
.738
.885
.973
.476
.709
-.220
.806
• 951*
.982
.835
.976
.989
.920
.756
.750
.826
.898
.979
.186
.976
.987
.812
.865
.454
.935
.953
.910
.916
.978
.992
.935
.986
.703
.845
.968
.987
.718
.926
.981
.958
• 9^9
.906
%
1.0744
1.2501
1.5803
.8652
1.1797
1.3619
1.0720
.5700
.0778
.^595
.3871*
.1336
.511*8
.2986
.2362
.4263
.4000
.2362
.0656
.1759
.1800
.1358
.3764
.5308
.1983
.2090
.0744
.2840
.1998
.6575
.1423
.2312
.5^70
.1493
.1498
.1551
.2142
.2074
.7184
.0874
.2658
.7103
.1318
.1876
.2228
.2473
.2218
.8527
.1665
.1775
.6220
.1751
.2217
.1484
.1327
.2508
.6585
.1388
.2366
1.0107
.2084
.3110
1.6228
cv
£
20.8
9.5
13.9
12.9
7.0
7.0
7-9
19.4
117.2
6.9
25.1
54.6
10.5
27.2
29.2
25.2
37."*
49.1
32.3
23.1
43.6
46.8
22.6
9.4
63.1*
60.3
57.3
32.2
17.1
0.4
28.0
15-2
3.0
14.3
66.8
17,2
26.7
18.4
20.0
42.0
18.1
15.8
54.1
29.6
79-6
35.6
24.8
8.3
5.0
5.6
10.9
21.9
19.0
38.8
36.6
8.2
4.7
32.0
22.0
2.1
25.1*
18.0
2.6
^
X5
611.2
1358.
5357.5
608.2
1219.2
4236.
871.
572.8
71.9
249.8
229.8
449.6
191.
214.0
235.1
218.5
196.
100.5
95.
141.4
187.
116.
209.1*
766.4
122.7
155.1
187.7
215.6
315.
1645.2
216.6
273.8
1485.6
210.5
292.1
1120.
196.8
183.8
1387.6
160.7
252.8
1277.8
211.8
184.2
273.2
253.6
216.6
1188.4
188.
23^.7
119**. 5
197.8
214.1
161.
204.9
268.0
804.8
222.6
296.2
2156.
228.8
281.3
Cv
%
28.1
12.2
23.2
25.6
i+. 7
5.0
21.0
58.3
6.7
26.7
13.1
17.3
11.5
12.1
12.8
10.2
7-1*
18.2
11.7
9.3
10.2
12.7
26.0
8.8
24.9
34.0
9-5
9-1*
12.6
15.9
12.2
5-5
14.6
10.3
18.7
7'k
6.8
7.6
3.5
8.6
6.1
2.3
13.2
10.7
7.9
11.5
3.6
6.6
13.9
2.8
11.7
7.2
5.0
3.5
17.1
3.4
3.6
17.9
15.1
1.4
4.1
6.8
ss
mg/4
4.06
5.41
4.43
4.40
6.88
4.88
5.22
1.29
0.95
4.02
5.17
45.46
3.26
2.63
29.59
3.98
3.46
7.44
2.84
2.71
19.51*
2.87
l*.77
20.25
2.87
2.95
™
3.30
5.00
11.25
3.90
4.42
10.90
3.60
4.17
2.17
3.48
2.92
19.23
2.12
3.21
17.13
2.58
3.81
2.33
no
-------
TABLE 18 (Continued)
Date
12-16
1970
1- 5
2-18
3- 3
3-18
3-26
4-15
4-23
4-30
5- 7
Sample
ICR B
ICR C
L-III
ICR C
L-III
ICR C
L-III
ICR C
L-III
ICR C
L-III
ICR C
L-III
ICR C
L-III
ICR C
L-III
ICR C
L-III
ICR C
L-III
Gone.
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
i;
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
A
.147
.091
.269
.073
.117
.329
.126
.139
.123
.056
.234
.538
.059
.C4o
.086
.J-ii
.149
.157
-.027
.074
.314
.273
.302
.285
.243
.213
.121
.160
.219
.156
.160
.175
.066
.080
.088
.189
.454
.626
.251
.254
.282
.226
.134
.321
..176
.068
.238
.179
.145
.016
.118
.171
.175
.089
.108
.123
.193
.217
.322
.173
.051
.304
Corr.
Coef.
.842
.696
.830
.711
.872
.976
.872
.819
.908
.845
.963
• 990
.816
.449
.522
.836
.770
.824
-.239
.784
.955
.958
.977
.937
.940
.946
.953
.943
.816
.977
.932
.981
.856
.867
.649
• 925
.977
.971
.939
.924
.961
.976
.905
.917
.969 •
.393
.937
.976
.951
.335
.974
.954
.953
.895
• 907
,867
.960
.958
.940
.972
.798
.981
1 1 1
"b
.2319
.2159
• 3354
.1558
.2037
.4035
.2035
.2508
.1626
.075
.332
.656
.110
,122
.274
.358
.344
.335
.151
.112
.462
.405
.385
.466
.385
.258
.157
.207
.453
.196
.224
.225
.094
.108
.242
.316
.512
.858
.377
.425
.418
.302
.195
.556
.247
.117
.355
.239
.205
.056 .
.143
.236
.222
.122
.166
.229
.286
.306
.522
.224
.084
.385
cv
20.1
30.0
44.6
45.7
23,4
16.9
33.6
21.7
22.4
21.0
8.6
5.1
37.7
115.7
28.5
4.3
13.5
9.3
26.8
36.7
11.6
12.3
10.5
4.9
5.3
20.3
23.8
32.5
17.4
15.8
24.8
9-9
31.6
17.9
24.7
12.1
12.8
12.9
12.4
12.6
4.2
10.3
36.1
2.2
10.5
82.2
17.0
8.6
15-9
60.3
14.9
25.6
9.2
39.4
13.0
19.6
7.7
15.6
3.5
17.5
32.6
IS. 2
Xs
88.4
78.2
152.6
65.6
88.2
183.2
85.8
91.3
73.2
111.0
205.0
646.0
109.8
63.4
165.7
261.0
317,7
256.7
110.8
181.9
212.7
179.9
145.4
200.2
189.4
179.4
123.2
148.2
235.0
133.5
136.8
194.8
91.9
101.8
121.7
156.5
609.6
1598.0
165.6
170.7
311.9
141.0
95.8
217.4
167.8
104.1
247.4
161.5
147.6
114.4
114.0
144.5
232.1
98.4
.111.5
132.9
176.6
200.4
272.4
162.8
100.1
202.2
-i -,— ,
cv
19.3
10.4
37.0
10.4
4.4
16.3
9-9
14.0
15.2
6.9
8.7
2.7
3.3
28.6
23.6 .
9.5
6.1
7.6
9-9
12.4
10.6
2.3
9.4
4.8
9.9
9.8
3.7
5.5
14.7
5.3
9.9
4.4
4.6
12.3
11.1
2.1
16.5
10.1
15.2
5.6
2.7
4.1
5.6
7.8
4.1
34.5
11.0
3-3
2.3
9.2
6.6
11.3
14.9
1S.O
8.9
3.9
2.9
5.1
4.0
3.8
3.6
5.1
1 i i 1 ii 1
SS
mg/tf
0.38
1.30
3.32
0.52
3.82
0.75
1.06
0.97
2.05
3.93
7 81
1.42
1.10
1.25
2.41
4 19
5.08
4.34
1.02
0.98
3 88
3.97
2.47
4.52
3.23
0.92
2.71
2.70
1.62
2 08
2.66
1.88
2.19
2.23
1.4.0
3.12
11.47
9-55
3.28
3.90
5.35
3 26
1 77
3.03
5 8l
4.66
6 is
5 87
5.69
3.49
3.53
4.24
4.88
3.10
3.08
2.56
2.51
3 12
2.52
2.35
0.93
1.59
111
-------
TABLE 18 (Continued.)
Date
5-19
5-27
6- 1*
7-ld
7- 7
7-16
V-;M
7-30
8- 7
8-11*
Sample
ICR C
L-III
ICR C
L-III
ICR C
L-III
ICR C
L-III
ICR C
L-III
ICR C
L-III
JCH C
L-III
ICR C
.L-III
ICR C
L-III
ICR C
L-III
Cone.
*
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
•*bj
.086
.170
.250
.045
.21*7
.157
.165
.167
.161
.077
.079
.073
.058
.010
.OU6
.087
.102
.385
.1*09
.233
.t*53
.382
.137
.109
.081
.102
.317
.169
.170
.11*7
.220
.190
.177
.200
.rjK
.1/11
.108
.051*
.126
.078
.099
.081*
.107
.157
.182
.31*2
.098
.152
.218
.296
.306
.073
.087
.108
.138
.516
.110
.057
.138
Corr.
Coef.
.918
.992
.986
.632
.753
.975
.975
.932
.966
.811*
.817
.931*
.709
.203
.561
.853
.652
.933
• 959
.989
.955
.990
.983
• 97-8
.968
.980
.975
.887
.967
.957
.91*2
.835
.958
.981*
,'X)1
.'/•I
.'/CO
.802
.961
.901
.863
• 971*
.952
.991*
•986
.960
.957
.758
.973
.991*
.980
.818
.953
.919
.992
.916
.939
.818
.930
A
^
.11*5
.181
.279
.102
.601*
.193
.190
.272
.196
.155
.161
.093
.11*5
.061*
.131
.173
.305
.61*1
.611*
.276
.695
.1*62
.171*
.132
.108
.120
.1*18
.275
.231*
.163
.338
.1*02
.223
.256
.981.
.;VL
.eiii
.103
.160
.131*
.128
.112
.139
.170
.219
.397
.128
.372
.273
.31*1*
.1*00
.110
.123
.11*1
.11*6
.639
.165
.105
.167
*
10.8
7-9
9.8
25.5
7A
17.2
11.2
13.7
21.0
27.5
33.1
16.2
21.1
61.7
2i*. 6
15.6
i*.5
1-5
1.8
l*.8
3.2
11*. 5
6.0
6.2
21.9
16.0
9-9
31.5
l*.7
30.1*
19.3
8.9
11.8
9.1
P.'t
J'j.:1
li.u
33-9
36.6
32.5
58.3
13.9
19.2
5.2
7.3
20.2
13.5
13.3
29.6
9.1*
12.7
23.5
1.5
1*3.0
8.1
16.6
21.1
16.3
53.0
A
X5
161*. 1*
211*. 2
381.6
10U.2
2}8.1*
125.7
126,2
ll*0.1
121.8
87.3
109.7
102.0
87-0
83.2
77.3
79.1
77-7
337.2
386.7
188.3
1*11.3
220.9
83.2
79.5
73.6
67.9
i'*7.3
92.0
88.3
97.9
123.6
11*1.7
108.8
132.9
•HP. 7
li:'. I
li'i.'i
58.9
yo.i
72.1
82.5
87. H
91.7
85.7
126.8
208.7
70.3
107.9
15^.9
169.7
215.9
70.1
66.1*
102.0
108.9
1*1*8.9
88.8
82.0
78.1*
s-
2.8
i*.6
8.1
11.9
3.0
5.8
6.2
2.9
9.5
5.7
3.8
6.6
7.2
9.1*
8.2
3.2
3.6
3-6
l.l
7.6
0.3
1.7
3.8
7.1*
2.3
1.2
i*.8
3.8
8.2
12.0
8.5
*.7
13-5
i*.l
7.0
'/.'.•
6.1
5.6
5.8
"*.9
l.l*
1.7
7-7
1.1*
2.3
22.6
8.7
6.7
5.7
3.3
0.9
11-7
*.5
5.0
3.7
63.8
6.1
5.7
15.5
SS
aig/t
1*.18
5.3"*
6.56
1.21
2.88
2.81
3.15
2.20
2.98
1.66
1.78
2.12
2.03
2.17
1.29
1.39
1.95
6.39
9-91*
it. 32
7.81*
3.76
2.25
1.95
2.05
1.76
3.03
1.76
1.78
2.37
2.22
1.26
3.20
2.50
0.35
I1.';!)
;.-.oo
2.36
f.S5
2.21
2.05
2.51
2.89
3.00
3.<*7
5.08
2.26
2.16
3.28
3.97
l*.ll
1.00
1.17
2.11*
1.97
10.75
1.95
l.tti*
2.11
112
-------
TABLE 18 (Continued)
Date
8-19
8-26
9- 1*
9-10
9-17
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1.
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
%';
.074
.059
-.016
.061
.066
.080
.075
.219
.144
.079
.076
.046
.061
.069
.058
.O4i
.065
.052
.039
.147
.093
.206
.170
.262
.104
.131
.092
.060
.082
.124
Corr.
Coef.
.879
.946
.936
.946
.974
.500
.983
.983
.846
.928
.914
.990
.668
.719
.866
.991
.860
.917
.570
.839
.988
.963
.861
.968
.405
.916
.896
.975
.930
.945
.'('ill
.
.626
.864
-.373
.823
.596
.600
.665
.955
.931
.885
.764
.754
.895
.895
.749
.897
.466
.591
.562
.908
.696
.939
.950
.981
.775
.905
.852
.941
.830
.939
*b
.214
.291
.455
.376
.159
.234
.175
.127
.109
.193
.232
.184
.342
.296
.412
.146
.192
.088
.079
.280
.330
.148
.115
.101
.207
.268
.238
.120
.129
.117
. I'A)
.IVY
.169
.084
.044
.105
.203
.264
.216
.294
.215
.092
.157
.099
.107
.117
.064
.069
.155
.100
.120
.239
.244
.295
.242
.332
.188
.198
.112
.091
.146
.157
*V
4.4
2.0
14.5
29.7
22.6
14.7
29.6
16.8
22.8
1.3
4l.O
13.8
13.0
2.2
4.8
4.7
26.6
32.6
60.0
24.5
10.0
9.0
30.4
28.1
32.8
13.3
33.4
2.7
7.5
16.7
W.I',
'j.<>
6l.6
8.7
4l.2
72.4
31.8
6.3
15.5
35.5
19.3
19.5
6.6
27.8
16.9
15.6
44.6
35.5
21.4
8.2
48.7
7.7
15.2
8.1
13.5
5.4
44.8
18.7
33.9
20.6
42.9
18.3
Xs
85.6
114.5
197.7
187.7
98.9
78.7
52.8
47.1
44.8
41.6
44.1
36.4
55.2
56.7
78.8
44.5
85.2
47.7
52.4
68.4
96.9
58.7
47.9
38.0
56.8
67.6
74.0
64.4
60.3
39.9
.!.:").')
i4',. ;>
110.7
120.4
84.8
96.0
65.9
65.2
68.5
131.5
100.5
82.7
80.9
70.0
66.0
82.0
73.3
68.0
88.1
69.5
65.9
110.7
91.6
90.8
95.6
124.4
68.7
78.4
70.7
73.9
75.3
64.4
Ci
4.5
2.7
20.9
4.1
7.0
0.6
9.7
5.9
8.0
8.6
18.1
1.4
5.9
4.7
6.6
5.0
18.6
0.9
20.4
23.8
3.1
6.1
8.2
3.4
14.0
5.8
6!o
4.0
3.4
'j.tt
0.4
3.0
7.1
5-9
9.8
8.6
2.0
4.3
19.1
12.1
10.2
8.7
1.0
1.2
4.8
6.9
0.6
30.9
1.3
7.5
2.5
4.8
13.6
7.0
1.4
23.8
10.9
16.6
2.4
14.0
11.7
ss
ms/t
1.54
2.17
2.53
3.24
1.65
1.03
0.92
1.74
1.32
1.42
0.81
1.09
0.57
0.97
1.32
0.72
0.72
0.83
0.53
2.03
1.86
0.56
0.53
0.45
0.64
0.97
0.36
0.39
j'.ll'i
3.28
2.19
1.47
2.30
2.00
2.06
2.76
4.91
?.85
2.27
1.74
1.17
0.58
0.75
1.03
0.78
0.86
0.88
1.92
2.28
2.24
2.75
6.97
8.14
1.78
2.00
2.06
1.67
1.58
1.86
113
-------
TABLE 18 (Continued)
Date
11- 6
11-11
11 -l£
11-2-
12- ?
12-15
19"!
1- c
l- = ~
2-1C
2-22
Sample
ICR C
L-III
ICE C
L-III
ICR C
L-III
ICR C
L-III
ICR C
L-III
ICR C
L-III
ICR C
L-III
ICR C
L-III
ICR C
L-III
ICR C
L-III
Cone.
*
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
IOC
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
r
10
100
1
10
100
J\
^bl
.225
.228
.222
.236
.108
.076
.179
.182
.148
.024
.045
-.231
.017
.057
.064
-.026
-.005
-.030
-.040
-.017
.131
.017
.002
-.025
.200
.348
.151
.191
.002
-.005
.257
.321
. .107
.247
.325
.105
.013
.024
.453
.194
.028
.122
.571
.052
-.009
-.199
-.101
-.107
.319
-.119
-.115
-.210
-,l4o
.202
-.207
.173
.015
-.J4o
Corr.
Coef.
.937
.964
.974
.966
.991
.860
.802
.853
.824
.344
.632
-.795
.571
,84o
.635
-.530
-.122
-.026
-.600
-.361
.758
.698
.049
-.492
• 793
.939
.919
.'962
.021
-.172
.950
.953
.608
.862
.913
.874
.072
.098
.969
.767
.377
.834
.935
.759
-.218
-.816
-.794
-.825
.711
-.669
-.591
-.686
-.719
.703
-.910
.991
.377
-.927
A
^
.366
.335
.288
.313
.122
.092
.408
.371
.286
.095
.107
.049
.043
.078
.194
.020
.055
.018
.038
.044
• 303
.040
.033
.010
.517
.565
.248
.241
.064
.015
.401
.492
.343
.481
.551
.124
.137
.108
.635
.272
.127
.170
.942
.082
.057
.027
-.028
-.079
.725
.019
• 139
.020
.091
.304
-.148
.206
.031
-.123
t
11.1
7.0
8.4
19.4
16.7
4o.4
3-4
1.2
27.2
78.3
19-5
72.1
19.6
11.2
13.5
87.9
111.2
251.6
113.4
51.6
19.8
54.7
9^.3
9"t-5
28.3
4.5
3.9
10.6
1.2
136.6
1.9
6.8
20.5
ki
10.4
14.5
33.1
78.1
12.4
63.9
34.5
31.0
4.1
25.8
27.3
550.0
-101.9
-74.1
42.1
117.8
84.7
1657.6
24.8
95.1
-15.0
3.4
34.7
-30.2
Xs
176.5
184.8
165-9
203.3
124.1
83.3
127.2
131.9
107.5
97.6
96.7
18.9
56.1
63.9
68.1
47.6
48.0
43.3
57.1
62.3
111.2
53.6
46.8
41.3
113.3
191.3
77.6
103.2
40.3
39.4
141.9
175.1
67.9
142.3
174.9
58.9
64.8
70.5
369.5
125.9
40.3
72.9
424.3
49-3
38.3
20.2
22,9
24.7
90.8
18.9
24.4
20.7
9.6
48.1
13.6
101.9
50.3
5.9
5-
1.7
0.4
11.5
11.5
2.6
14.1
0.3
7.1
14.0
11.2
7.5
19.1
3.1
6.1
5.0
8.5
8.5
7.8
6.9
7.3
6.0
2.9
9.4'
6.8
37.9
4.7
8.6
11.9
14.8
6.5
1.0
1.2
4.8
1.9
11.4
13.4
44.6
53.3
14.6
44.6
12.8
23-9
2.3
13.7
2.7
18.1
17.1
23.5
41.2
4.0
13.9
63.6
3.8
54.5
17.8
1.7
8.6
14.1
ss
mg/t
5.03
5.00
3.49
5.11
2.75
2.14
1.89
2.50
2.36
1.85
1.29
5.65
16.06
16.47
18.27
15.63
14.94
16.79
14.00
13.44
16.06
12.52
13.40
12.31
1.89
4.60
3.36
1.94
0.77
1.05
3.09
5.14
2.50
4.66
6.94
5.51
3.91
3,44
9.44
6.09
2.27
3.08
9.37
2.77
1.72
1.79
0,76
0.71
2.40
0.71
0.46
0.86
0.11
1.27
0.66
4.74
2.74
2.47
-------
TABLE 18 (Continued)
Date
3- 9
3-15
3-24
4- 5
4-19
5- 5
Sample
ICR C
L-III
ICR C
L-III
ICF C
L-III
ICR C
L-III
NJH C
L-III
ICR C
L-III
Cone.
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
1
10
100
A
"b*
-.093
.022
-.235
.068
.366
-.199
-.195
.050
-.199
.093
.055
-.215
-.030
.103
.021
-.020
T.oo9
-.w>
.',17
.488
.358
.567
.373
-.P71
>u
.522
.550
.4J8
.312
-.051
.341
.300
.349
.217
.027
Corr.
Coef.
-.685
.220
-.810
.796
.936
-.741
-.888
.905
-.761
.915
• 754
-.803
-378
.862
.376
-.259
-.139
-.'/•?
.'>i8
.893
.882
.912
.797
-.763
.'//;
.921
.906
.936
.875
-.181
.926
.927
.923
.947
.841
Ob
-.061
.037
-.134
.096
.592
.103
-.128
.075
.021
.152
.131
.008
.030
.157
.082
.059
.055
-.165
.816
.884
.677
1.006
.810
.059
,7'ib1
.889
.955
.716
.514
.422
.579
• 503
.597
.34o
.044
s-
-27.8
67.1
-11.8
34.8
8.3
89.3
-57.0
1.6
160.2
7.2
6.9
1439.5
53.6
6.6
55.3
1.7
104.5
-30.7
o.O
10.3
16.6
1.0
10.4
386.8
0.7
7.8
0.4
7.2
11.0
8.3
4.2
7.3
7.8
1.4
38.5
*-» 'mat—-, t -,fr.
24.8
43.7
12.5
48.5
143.1
17.5
29.9
73.3
24.0
82.4
80.5
20.4
50.9
89.6
63.9
55.9
6?.o
Pi.')'
L'VO.'l
284! 7
159.1
317.9
136.3
ll.l
'.•'j\.<>
yji . 7
360.0
286.3
168.0
30.3
303.3
303.1
337.7
113.2
44.7
%V
29.0
35 1
s s • •*-
13.4
10.8
6.8
25.8
2.6
35.4
5.6
4.7
9.6
19. y
14.1
10.5
17.8
11.7
17.5
'i 8
2.*8
6 7
v * f
6.6
34.4
37.6
'' • ' *
U4
5.0
32.9
6.3
2.7
2.9
0.8
4.9
1.4
mg/t
aTeat alga §.. graolle, hand counted during period 10-3-19t>8 to 7-1-1969.
^Test alga S. caprlcornutum, counted by Coulter Counter during period 7-10-1969 to 12-16-1969.
CTest alga culture of S._ capricornutum contaminated by Chlorella ep. during period 9-10-1969
to 10-16-1969.
this time period three replicate samples replaced the five replicate samples that were
previously used.
115
-------
SELECTED WATER i. Report No.
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
2, 3. Accession No.
w
4. Title 5- Report Date
EUTROPHICATION OF SURFACE WATERS - INDIAN CREEK RESERVOIR,
7. Author(s)
P. H. McGauhey, D. B. Porcella, and G. L. Dugan
9. Organization
11. Contract I Grant No.
Lake Tahoe Area Council, South Lake Tahoe, Calif.
8. Performing Organization
Report No.
10. Project No.
13. Type of Report and
Period Covered
12. Sponsoring Orgmitttion
IS. Supplementary Notes
16. Abstract
Beginning in April 1969 field and laboratory analyses were made on approximately a
•weekly basis to observe the relationship between the quality of water in Indian Creek
Reservoir and that of reclaimed water exported from the South Tahoe Public Utility
District, which comprised some 70 percent of its annual input. Reclaimed water contained
0.01 - O.oii- mg/j0 of phosphorus and more than 15 mg/4 of ammonia. Initially the reservoir
would not support fish life but as the reservoir matured some 70 percent of influent
nitrogen was lost to the atmosphere continuously by nitrification-denitrification in the
system. By March 1970 the reservoir was an excellent trout fishery. Good general
biological productivity indicated access to other sources of phosphorus, probably soil
and surface runoff. Bioassays showed the growth stimulating ability of reservoir water
exceeded that of influent reclaimed water. It is concluded that the reservoir responds
to more complex factors than those measurable by analyses of reclaimed water; that the
reservoir should be monitored further to determine whether it has stabilized or is
subject to further change; and that the optimum degree of treatment necessary for
recreational waters should be determined as a guide to design of appropriate waste
treatment and water reclamation processes.
*Eutrophicatioii, *Denitrification, ^Reclaimed Wastes, *Aquatic Productivity, *Bioassay,
*Ldmnology, ^Cycling Nutrients, *Benthos, Aquatic Microorganisms, Algae, Vascular Plants,
Fish Population, Tertiary Treatment, Nutrients, BiomasB
lib. Identifiers
*Indian Creek Reservoir, *Sewage Export, *South Tahoe Public Utility District,
Lake Tahoe Area Council, EPA Demonstration Grant Lake Tahoe
17c. COWRR Field & Group 05C
18. Availability «•
30. Security Glut.,
(Put)
21. No. of Send To:
•Page*
Prlft WATER RESOURCES SCIENTIFIC INFORMATION CENTER
• «*VW II Q riFDADTUCTlUT nET TLJC? IKIYFBIAn
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON, D. C. 20240
P. H. McGauhey I Institution California University
WRSIC 102 (REV. JUNE l»7l) *US' GOVERNMENT PRINTING OFFICE: 1972-*84-t«2/*2
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