WATER POLLUTION CONTROL RESEARCH SERIES 16010 DSW 05/71
Eutrophication Of Surface Waters-
Lake Tahoe
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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, B.C. 20460.
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EUTROPHICATION OF SURFACE WATERS - LAKE TAHOE
Lake Tahoe Area Council
South Lake Tahoe
California 95705
for the
ENVIRONMENTAL PROTECTION AGENCY
Grant No. 16010 DSW
May 1971
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $1.25
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EPA Review Notice
This report has been reviewed by the Environmental Protection
Agency and approved for publication. Approval does not
signify that the contents necessarily reflect the views and
policies of the Environmental Protection Agency nor does
mention of trade names or commercial products constitute
endorsement or recommendation for use.
11
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ABSTRACT
A study of the factors leading to the eutrophication of surface waters, with
special emphasis on Lake Tahoe, was conducted over a 5-year period (1966-1971)
through a series of Demonstration Grants to the Lake Tahoe Area Council by the various
federal agencies now (1971) known as the Water Quality Office of the Environmental
Protection Agency. Increasing enrichment of national waters leading to objectionable
algal blooms, plus a widespread public interest in preserving the unique clarity of
Lake Tahoe, was justification for the project. Pursuant to a research plan, a
survey of the nutrient and other chemical constituents was made of surface waters
from developed arid undeveloped land areas, sewage effluents, seepage from septic
tank percolation systems and refuse fills, drainage from swamps, precipitation, and
lake Tahoe Wat;er. Simultaneously, the algal growth stimulating potential of samples
from these sources was made by flask bioassay, utilizing the alga Selenastrum gracile
as a test organism. Both the maximum growth rate (p.) and the maximum cell count (X)
attained in a 5-day growth period wers 'used to measure algal response to nutrients.
Continuous flow assays of the biomass of indigenous Lake organisms produced
by various concentrations of sewage effluent in Lake Tahoe Water were then made in
ponds simulating the shallow portions of the lake. Other sources of nutrients
proved too dilute to justify pond assays but flask assays and chemical analyses
were made for more than 2 years on 3 major creeks. Twenty-eight other creeks and
precipitation were monitored by chemical analysis only.
An evaluation of the eutrophication potential revealed by the results led
to many conclusions. Among the most significant were that Lake Tahoe is nitrogen
sensitive and responds to this nutrient in proportion to its concentration. Creeks
draining developed land carried twice as much nitrogen as those draining relatively
undisturbed watersheds. During active development periods this ratio rose to
3/1 to 10/1. The combination of all surface streams plus precipitation contained
about twice the concentration of nitrogen as Lake Tahoe or the undisturbed areas .
Evidently human activity in the Lake Tahoe Basin doubles the natural inflow of
nitrogen to the lake.
It was estimated on the basis of hydrological and chemical data that
exporting all sewage would remove some TO percent of the total nitrogen from the
basin. However the 30 percent over present lake concentrations contributed by
streams and precipitation on the lake surface is equivalent to the secondary
sewage effluent of more than 33^000 people, when the concentration of nitrogen in
the lake is taken as a baseline value.
Recommendations are made for protection of the shallows and for evaluating
the effect of influent sediments.
This report was submitted in fulfillment of Demonstration Grant No. 16010
DSW under the sponsorship of the Water Quality Office, Environmental Protection
Agency.
iii
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CONTENTS
ABSTRACT ill
LIST OF FIGURES ix
LIST OF TABLES x
SECTION I: SUMMARY AND CONCLUSIONS 1
Summary 1
Survey of Waters in the Lake Tahoe Area 1
Pond Assays of Wastewater Effluents 1
Assay of Surface Waters 2
Evaluation of Eutrophication Potential 2
Auxiliary Studies 2
Conclusions 2
Survey of Waters in the Lake Tahoe Area 3
Pond Assays of Wastewater Effluents h
Assay of Surface Waters 5
Evaluation of Eutrophication Potential 7
Auxiliary Studies 9
SECTION II: RECOMMENDATIONS - 11
SECTION III: RESULTS OF STUDY 13
Chapter
I. INTRODUCTION 13
Need for Study 13
Objectives of Study 15
Nature and Scope of Report 16
II. ASSAY TECHNIQUES 17
Introduction 17
Bioassay Techniques ]_y
General Considerations y
v
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CONTENTS (Continued)
Chapter F&ge
Flask Assay 17
Continuous Flow Assay 19
Expression of Results 19
Interpretation of Results 21
Theoretical Considerations 21
Limitations of Bioassay Techniques 22
Chemical Assay Methods 23
Preparation of Samples 23
Analytical Procedures 23
Evaluation of Assay Techniques 2k
Bioassays 2k
Chemical Analyses 25
Carbon14 25
Results 25
III. SURVEY OF WATERS IN THE LAKE TAHOE AREA 2?
Introduction 27
Flask Assays 2?
Lake Tahoe Water 2?
Other Sources (Chemical Analyses) 27
Other Sources (Growth Response) 27
Conclusions 32
Chemostat Assays 33
IV. POND ASSAYS OF WASTE WATER EFFLUENTS 35
Introduction 35
Nature and Operation of Pond Assays 35
Physical Nature of the Pond System . 35
Operation of Pond Assays 37
Measurement of Growth Response ..... 37
VI
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CONTENTS (Continued)
Chapter Page
Physical and Chemical Analyses 39
Environmental Data 39
Analysis of Data 39
Results of Pond Assays 39
Environmental Factors 39
Biomass Measurements ^-1
Inventory of Quality Parameters in Pond Assays k2
SS and VSS ^5
Nitrogen Compounds U6
Phosphorus ^9
Growth-Limiting Nutrient 50
Materials Inventory 51
Kinetic Analyses 52
Flask Assays of Pond Effluent 53
V. ASSAY OF SURFACE WATERS 55
Introduction 55
Quality of Lake Tahoe Water 55
Chemical Analyses 55
Growth Response 57
Evaluating Results 58
Quality of Creek Waters 59
Chemical Analyses 59
Growth Response in Creek Waters 65
Relation of Growth Response to Nutrients 68
Comparison of Growth Response: Lake Tahoe and Creek Waters . . 71
Conclusions 72
VI. EVALUATION OF EUTROPHICATION POTENTIAL 73
Introduction 73
vii
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CONTENTS (Continued)
Chapter Page
The Basic Approach 73
Chemical Analyses 7^
Hydrologic and Nutrient Budgets 78
Hydrological Factors 78
Nutrient Inventory 88
Evaluation of Results 91
Comparison of Nutrient Concentrations 91
Evaluation of Other Factors 95
SECTION IV: ACKNOWLEDGMENTS 99
SECTION V: REFERENCES 101
SECTION VI: APPENDICES 103
VI11
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LIST OF FIGURES
Figure Title Pa
2-1 Typical Flask (and Chemostat Apparatus) Assay Used
in Study ............................ l8
2-2 Typical Microbiological Growth Curve, Flask ............ 20
4-1 Layout at Experimental Ponds .................... 36
4-2 Variation in Environmental Factors During Pond Assays ....... 40
4-3 Variation in P04 -P and Total P in Creek Waters ........... 44
5-1 Relationship of Growth Parameters and Nutrients
Near -Shore Lake Tahoe ...................... %
5-2 Variation in Concentration of Nitrogen Compounds
in Creek Waters ............ ............. 62
5 -3 Variation in Organic and Total Nitrogen in Creek
Waters ............................. 63
5-4 Variation in P04 -P and Total P in Creek Waters ........... 64
5-5 Variation in Concentration of Selected Water
Quality Factors in Creek Water ................. 66
5-6 Variation in Volatile Solids and Suspended Solids
in Creek Waters ......................... 6?
5-7 Comparison of Algal Growth Response Parameters in
Flask Assays of Creek Waters .................. 69
6-1 Mean Annual Precipitation in the Tahoe Basin ............ 79
6-2 Sub -Basin Drainage Areas, Lake Tahoe Basin ............. 80
6-3 Average Monthly Flow Percentages for Continuously
Gaged Stations in the Tahoe Basin ................ 86
6-4 Calculated Precipitation vs. Measured Runoff in the
Tahoe Basin ........................... 87
6-5 Average Annual Hydrologic Inventory of the Lake Tahoe
Basin for the Water Years 1961 through 1970 ........... 90
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LIST OF TABLES
Table Title Page
5-1 Maximum Growth Rates of S. gracile in Lake Tahoe ₯ater 28
3-2 Nitrogen and Phosphorus Concentrations in Various Water Samples ... 29
3-3 Maximum Growth Rates of S. gracile Attained ₯ithin 6 days
in Flask Assays of Various Samples 30
4-1 Experimental Design of Pond Assays 38
4-2 Day-to-Wight Variation in Air and Water Temperatures 4l
4-3 Comparison of Biomass Estimates Between Ponds
Receiving the Same Effluent 43
4-4 Inventory of Suspended Solids in Pond Assays 45
4-5 Inventory of Volatile Suspended Solids in Pond Assays 46
4-6 Inventory of Soluble Ammonia -N in Pond Assays 4?
4-7 Inventory of Soluble (N02 + N03)-N in Pond Assays 4?
4-8 Inventory of Soluble Total Inorganic -N in Pond Assays 48
4-9 Inventory of Soluble Total -N in Pond Assays 48
4-10 Inventory of Soluble P04-P in Pond Assays 49
4-11 Inventory of Soluble Total P in Pond Assay 50
4-12 N/P Ratios in Pond Assays 51
4-13 Calculated Percent Inorganic -N in VSS 52
4-l4 Maximum Growth Rates, jl and jj^ } and Maximum Cell Concentration,
X5, Attained at the end of five days in Flask Culture of
Pond Samples Collected During Steady State Operation 54
5-1 Summary of Range of Algal Growth Response in Creek Waters and LTW 70
6-1 Analyses of Selected Constituents from Creeks Representing Sub-
drainage Basins in Different Stages of Land Development 75
6-2 Analyses of Selected Constituents from Mid and Near-Shore
Lake Tahoe Water 76
6-3 Comparison of Average Values of Selected Chemical Constituents
1968-1971 77
6-4 Comparison of Selected Data on Precipitation 78
6-5 Representative Tahoe Basin Weather Bureau Stations 82
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LIST OF TABLES (Continued)
Table
6-6
6-7
6-8
6-9
A-l
A -2
B-l
C-l
C-2
C-3
c-i*
c-5
c-6
D-l
D-2
D-5
D-4
E-l
E-2
E-3
E-4
E-5
Title
Estimated Runoff in Tahoe Basin
Lake Tahoe Hydrology Inventory
Annual Nutrient Inventory in the Lake Tahoe Basin
Comparison of Various Observed and Computed Nutrient Values
Modified Skulberg Nutrient Medium
Analytical Procedures
Chemical Analyses of Various Waters Surveyed in the Lake Tahoe Area .
Chemical Concentrations in Ponds (Assays 2-6)
Results of Analyses of Pond Input Waters
Pilot Pond Analyses
Pilot Pond Influent Chemical Analyses
Biomass Measurements
Simulated Secondary Effluent Feed for Pilot Ponds
Chemical Analyses of Shore and Mid -Lake Tahoe
Maximum Growth Rates and Maximum Cell Concentrations Attained at
the End of Five Days in Flask Culture of Lake Tahoe Water ....
Creek Water Analyses
Maximum Growth Rates; p^, i\,e> an<^ Maximum Cell Concentrations > 5t5,
Flask Assay of Creek Waters
Chemical Analyses of Surface Streams in Lake Tahoe Basin
Nutrient Inventory of Streams Discharging into Lake Tahoe
Chemical Analyses of Precipitation in the Tahoe Basin ........
Continuously Recorded Streams in the Lake Tahoe Basin
Rainfall -Runoff Coefficients for Continuously Gaged Streams in
Lake Tahoe Basins
Page
Qk
89
92
93
105
106
10?
109
116
118
130
132
135
137
138
139
11*2
1U3
151
152
153
i R),
xi
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SECTION I
SUMMARY AND CONCLUSIONS
SUMMARY
A study of the factors leading to the eutrophication of surface waters
was initiated in June 1966 through a demonstration grant to the Lake Tahoe Area
Council "by the Federal Water Pollution Control Administration (currently the Water
Quality Office of the Environmental Protection Agency). The need for such a study
was made evident "by a decline in the quality of surface waters in the United States
despite the concentrated efforts of pollution control agencies. Specific interest
in utilizing Lake Tahoe as the locale for such a study derived "both from the desire
of millions of citizens to preserve the unique clarity of the Lake, and from the fact
that the lake represented one of the few bodies of water in the world where eutro-
phication had not already progressed "beyond the point where its triggering mechanism
could no longer "be discovered. Thus Lake Tahoe offered an excellent opportunity to
explore on a laboratory and pilot scale the types of inputs which accelerate the
natural rate of eutrophication of water and at what concentrations they might have
a triggering effect.
The overall approach to the study was first to discover, "by the "best
available methods of analysis and bio-assay, what concentrations of nutrients might
be present in a number of possible sources, and to demonstrate their effect on algal
growth stimulation in Lake Tahoe water-
Survey of Waters in the Lake Tahoe Area
The sources selected for survey included sewage effluents following various
degrees of treatment; surface runoff from inhabited and uninhabited land areas;
seepage from septic tank percolation fields, refuse fills, and spray irrigation
systems; drainage from swamps; and water confined in keys and marinas. Waters
from such sources in the Lake Tahoe area were systematically analyzed. Flask
assays utilizing the alga Selenastrum gracile, were used to evaluate the growth
stimulating effect of various concentrations of samples in Lake Tahoe water; and
of the lake water itself. In later phases of the study S. capricornutum was subs-
tituted for S. gracile because a changeover from ocular counting of cells to machine
counting by a Coulter Counter required an organism with minimum tendency for algal
cells to persist in colonies. Growth stimulation in all flask assays was measured
both by the maximum number of cells produced during an assay period (x), and by the
maximum growth rate (|-i) attained during that period.
Pond Assays of Wastewater Effluents
Results of the survey of sources indicated that although no one was advo-
cating discharge of such material into Lake Tahoe, sewage effluents were the only
important waste waters of sufficient stimulating potential to justify their study
on a pilot scale. Consequently, a series of pilot ponds simulating the shallow
portions of Lake Tahoe were operated during the summer and fall seasons of 1968 and
1969- Continuous flow of Lake Tahoe water through these ponds was provided, and
biomass production was measured during detention periods ranging from 3 to 10 days,
with various concentrations of sewage effluents. Indigenous organisms (mostly
pennate diatoms) served as test organisms in both natural and enriched lake water.
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Increase in volatile suspended solids (VSS) was used to measure biomass. Flask
assays were made of the pond effluent and cell counts (x) and growth rates (u) used
to measure its residual growth stimulating ability.
Assay of Surface Faters
The effect of human activity in the Tahoe Basin was observed over a period
of 3 years "by analyses and flask assays of waters from creeks emanating from unde-
veloped land, developed land, and land undergoing intensive development. Ward
Creek and General Creek represented relatively undisturbed conditions until develop-
ment on the Ward Creek watershed began in 1969- Incline Creek, draining an area
undergoing rapid development of land for living and recreational purposes, provided
a basis for evaluating this type of human activity. The Upper Truckee Trout Creek
system gave a clue to the effect of long established human occupancy of land in
enriching surface waters. Rapid expansion of population in the Lake Tahoe Basin
limited the purity of assumption in each of the watersheds selected for study, but
when results were compared with those from Lake Tahoe water as a background the
assumptions proved valid and the differences between creeks were unmistakable.
Evaluation of Eutrophication Potential
The final phase of the project involved an estimate of the relative potential
of sewage effluents and other sources of nutrients to accelerate eutrophication.
The results of a program of chemical analysis of 31 creeks, including the four
previously mentioned; estimates of the nutrient input by precipitation; and miscel
laneous information concerning the inflow and outflow from Lake Tahoe were compared
with the observed concentration of nutrients in the lake . The result was more of an
inventory of nutrients than a nutrient balance but it made possible an estimate
of the importance of removing sewage from the basin. Also, from the comparative
data on undisturbed land (Ward Creek) and developed land (Truckee Trout) an
estimate of the relative effect of nature and man on enrichment of the lake was
made. Projecting all creek inputs to the equilibrium at any growth of population
level gave some clue as to what the growth of population may mean to Lake Tahoe
in terms of rate of enrichment.
Auxiliary Studies
In parallel with the foregoing series of studies experiments were run to
compare the continuous flow (chemostat) assay method with the flask assay method
of measuring growth response. The kinetics of growth response were determined by
use of the computer and statistical reliability was determined. The theory and
results of this aspect of the study were reported in a series of Annual Progress
Reports (l, 2, 3). At the low levels of nutrients prevailing in Lake Tahoe the
method, despite its theoretical advantages, could not be made to produce satis-
factory results in time to be used in achieving the objectives of the study.
Consequently, this aspect of the project activity is not discussed in detail in
this report,
CONCLUSIONS
The principal findings and conclusions relative to the several phases of the
project summarized in the preceding section include the following.
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Survey of Waters in The Lake Tahoe Area
1. Maximum growth rates of S . gracile in Lake Tahoe water were increased by
the addition of sources of nitrogen but unaffected "by similar additions
of phosphates, indicating that Lake Tahoe is nitrogen sensitive rather
than phosphorus sensitive as are most oligotrophic lakes.
2. Comparative growth rates "between surface water from Lake Tahoe and the same
water with added sodium nitrate were of the order of 29 percent per day versus
86 percent per day.
3- The ratio of nitrogen to phosphorus (N/P ratio) for all samples surveyed
(with one exception) ranged from 0.4 to 7-36, averaging 2.08, whereas the
N/P ratio for algal cells is reported (20) to range from 6-9 to 18. The
exception was septic tank seepage in which the N/P ratio was Ilk /I. because
of the vast ability of soils to adsorb phosphates .
h. At a concentration of 1$ sample in Lake Tahoe water sewage effluents of
all types (primary, secondary, tertiary, oxidation pond, and seepage from
septic tank fields); surface drainage from storm water; and rain water all
produced a growth rate of S. gracile considerably greater than the 29
percent per day (ftj-, = 0.29 day"1) observed for Lake Tahoe water alone.
Moreover, the rate difference increased with concentration (10$ and 50$).
5- Although the growth response was but little different between 1$ and
rain water chemical analyses showed beyond doubt that precipitation is an
important contributor of nitrogen to Lake Tahoe.
6. Melted snow, unlike rain which often occurs during thunderstorms, did
not differ from Lake Tahoe water in growth response at any concentration.
7. At the time when disposal of effluent from the STPUD plant involved spray
irrigation, direct assay of the effluent showed a marked ability to stimu-
late growth in S. gracile. However, samples taken from test borings in
the spray irrigation field had little growth stimulating effect. This
phenomenon was due to the adsorption of both phosphate and ammonia on soil
colloids and too short a time interval between application and sampling
for soil bacteria to convert nitrogen to the soluble nitrate form. Where
such time period did exist, as in septic tank percolation fields, the growth
stimulating effect of percolating sewage effluent was approximately 2 to k
times that of Lake Tahoe waters, depending upon the concentration.
8. Evidence of leaching from a refuse dump was observed as an increase in
organic nitrogen in a small stream as it passed the dump site. A comparison
of dry weather and rainy weather analyses of the stream, following a winter
frost heave, showed that increased nutrient concentration appeared in wet
weather. Therefore it is concluded that the difficulties of maintaining the
physical integrity of a landfill under severe winter conditions justifies a
policy of excluding such fills from the Lake Tahoe Basin.
9. Assays of growth response of a test alga, such as characterizes the flask
assay method, can measure only the residual potential of a water to
stimulate growth. Therefore, at times of the year when nutrients are tied
up in an algal bloom such an assay might show no evidence of eutrophication
potential when eutrophication is obvious to any observer . This phenomenon
was evident in assays of water from keys and marinas in the survey phase
of the project.
10. At the time of the survey (1967-68) Meeks Creek and Ward Creek were indis-
tinguishable from Lake Tahoe in the matter of growth response of S . gracile
in flask assays.
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11. Incline Creek, Toeing in the early stages of development on its watershed
showed little evidence of increased response at the time of the Survey. (See
"Assay of Surface Waters" for subsequent developments.)
12. Upper Truckee - Trout Creek,, draining an area of well established human
occupancy showed a definite increase in growth stimulation with increased
concentration in Lake Tahoe water.
13. General conclusions derived from the survey of possible sources of nutrients
in the Lake Tahoe Basin, "beyond the specific findings reported above were
that:
a. Sewage effluents represent the most important source of nutrients
which might trigger eutrophication of surface waters in the Tahoe Basin,
hence are suited to further study on a pilot scale.
b.. Septic tank leachings do not differ particularly from other sewage
effluents in their ability to produce algal growth in Lake Tahoe water
However, it was infeasible to collect them in sufficient amounts for
pilot pond studies.
c. Pond assays at various concentrations of waters from the Upper Truckee-
Trout Creek system might "be useful, but were impractical "because of
geographic relationships between source and pond installations.
d. Other creeks (see 10 and 11, a"bove) could be assayed in ponds only
at 100$ concentrations an undertaking neither feasible nor especially
useful under the project plan.
Pond Assays of Waste Water Effluents
ift-. Attempts to utilize S . gracile as a test alga in unfiltered Lake Tahoe
water in continuous flow steady state pilot ponds were unsuccessful
because the organism was soon overwhelmed "by indigenous lake organisms
(mostly pennate diatoms).
15- Filtration of lake water to remove indigenous organisms was not feasible
except at an unacceptable sacrifice of time and expense in re-equipping
the pond system. Consequently, indigenous organisms were used as test
organisms and the increase in volatile suspended solids (VSS) in comparison
with a similar increase in Lake Tahoe water was used to measure growth
response to added nutrients.
16. Growth stimulating response of organisms increased with concentration of
sewage added to Lake Tahoe Water.
17- Biomass produced by 0.1$ secondary effluent in LTW was about the same as
that produced by a 1.0$ tertiary effluent (STPUD Water Reclamation Plant).
18. There was no evidence that growth response was reduced, in either Lake
Tahoe water or other samples assayed, by cold weather which sent water
temperatures below the 10°C level at which biological activity is normally
seriously reduced.
19- Wind disturbance of the near-shore area of the lake was found to result in
pickup of both inorganic and organic solids. However, the effect on biomass
production when this occurred was damped out by the 5- day residence period
in the pond.
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20. From an inventory of nitrogen compounds it was concluded that with limited
exceptions, a decrease in all forms of nitrogen occurred during the MO-
BS say which correlated well with the observed increase in VSS .
21. Under steady state pond assays of secondary sewage effluent in Lake Tahoe
water at concentrations of 0.1$ and 1.0$, nitrogen was determined to be
the growth limiting nutrient. Phosphorus was limiting in assays of 1$
and 2$ tertiary effluent.
22. Simulated secondary effluent based on the addition of WHg-W, P04-P, iron,
and micronutrients produced a different growth response than did secondary
effluent of the same apparent analysis. It is concluded that life processes
themselves contribute growth stimulants which the analyses adopted for the
study did not reveal.
23. In pond assays of tertiary effluents the growth response was so severely
phosphorus limited that neither the materials balance nor the kinetic
equation yielded statistically significant correlation coefficients. The
apparent reason is that all data fall on the flat region of the cell mass
versus residence time curve.
2.k. The tertiary effluent assayed in the study was secondary sewage treatment
plant effluent which had been subjected to phosphate removal, carbon
filtration, and nitrogen reduction by ammonia stripping. However, because
the tertiary process itself was a new demonstration unit undergoing devel
opment, the residual M3-N in the effluent was in the range of 12 to IT
25. From the calculated percent of inorganic nitrogen in volatile suspended
solids produced during pond assays it is concluded that a good materials
balance for nitrogen was achieved; and hence that reasonable confidence
in the overall results of the nutrient inventory presented is justified.
26. In water as pure initially as Lake Tahoe water the total volatile suspended
solids at the end of pond bioassays is an accurate measure of biomass
produced.
27. From flask bioassays of the effluent from ponds it is evident that in
situations when one nutrient is severely limiting to algal growth a
bioassay of the water might lead to a false conclusion concerning its
nutrient value. If the limiting factor is phosphorus and Lake Tahoe is,
as evidence indicates, nitrogen sensitive, a major growth stimulant
(nitrogen) in a discharge to the lake could pass a bioassay test and still
do harm to the lake .
Assay of Surface Waters
28. From both chemical analysis and flask assays of growth response over the
period of study, it was concluded that there was no significant difference
between samples taken at a mid-lake station and those taken at the near-
shore station from which water was pumped for pond assays. Consequently,
it was further concluded that for the purposes of the study the near-shore
sample could be taken as representative of at least the top few meters of
Lake Tahoe water.
29. Five instances were found in the year 1970 when wind and storms resulted
in a disturbance of the near-shore sediments. On these occasions Total
SS exceeded VSS to a more than normal degree in near-shore waters, and
both exceeded the concentration of similar solids in mid-lake samples.
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30. Suspended solids in the shallow portions of the lake depreciated its
aesthetic quality locally when wind direction and velocity was right for
pickup of silt discharged to the lake as a result of land development.
31. From flask assays of Lake Tahoe water which had been enriched with added
nutrients in the form of secondary effluents and allowed to support algal
growth prior to flask assay of filtered samples, it was found that a
residual growth potential remained in excess of that normally existing in
Lake Tahoe water. Consequently algae removal from a waste water could not
by itself protect Lake Tahoe.
32. In analysis of growth rates, VSS, and chemical constituents over a one
year period,, evidence was found of the "residual potential" phenomenon noted
in Conclusion '9. However, because Lake Tahoe is nitrogen poor it supports
such a small biomass that the results of flask assays are not measurably
in error because of nutrients tied up in biomass. (in pond assays, where
large volumes of water were involved, the relative productivity of VSS
Toy raw on enriched Lake Tahoe water was readily determined).
33. Because, algal assays of membrane filtered samples measure only the residual
ability of a water to stimulate algal growth, the flask assay technique is
more useful in evaluating the growth potential of a waste water not already
producing algae than in assessing the eutrophication of surface water,
except in unique cases such as Lake Tahoe and some of its tributary creeks .
jk. During 1968 Ward Creek, which drained relatively undisturbed land, was
no different than Lake Tahoe in growth potential. Simultaneously, as
development of land on the Incline Creek watershed vas beginning, both
Incline and Upper Truckee Trout creeks averaged about 1.6 times the growth
stimulating potential of Lake Tahoe.
35. During the first 6 months of 1969, ₯ard Creek continued to parallel Lake
Tahoe . At the same time increased activity on the Incline watershed caused
Incline Creek to exceed the Upper Truckee Trout Creek system in produc-
tivity. Both continued to exceed Ward Creek and Lake Tahoe in stimulatory
potential.
36. In the latter half of 1970, activity in the Ward Creek area initiated a
response similar to that of Incline Creek. Upper Truckee Trout Creek
continued to exceed Lake Tahoe in growth potential, although less than
either of the two (Ward and Incline) more disturbed watershed.
37- Flask assays were shown to be capable of detecting changes in those water
quality factors which increase the rate of eutrophication of surface waters,
although no one can interpret the growth rates attained in such assays in
terms of the biomass which might result in an individual outdoor situation..
38. Cell counts (X^ ) and growth rates (p^) correlated well with nutrients
concentrations present in creek waters.
39- Algal growth in waters from undisturbed areas showed best correlations with
the concentration of the more stable forms of nitrogen and phosphorus, as
might be expected.
kO. Human occupancy of land under well developed conditions (e.g. Upper Truckee -
Trout Creek) showed an appreciable excess in algal growth stimulating nutrients
over that from land under natural conditions .
^1. Runoff from relatively undisturbed land as, for example, the Ward Creek
watershed in 1968 and the General Creek watershed in 1970, reflect essen-
tially the same growth stimulating properties as Lake Tahoe water.
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42. Land undergoing development is especially productive of algal growth
stimulating nutrients, at least under practices which have prevailed in
the Lake Tahoe Basin.
43 The presence of humans and human activity on a watershed definitely
increases the rate of eutrophication of its surface waters.
44. It is concluded that a definite increase in nutrients in creek waters
occurs as the level of occupancy and development of land increases, which
was evident in "both chemical analyses and bioassays.
45. Land management and land use controls are essential to a program designed
to minimize the rate of eutrophication of surface waters.
Evaluation of Eutrophication Potential
46. Chemical analyses of samples from 51 creeks discharging into Lake Tahoe
were on a periodic and systematic "basis for the period 1969 to 1970,
with especial emphasis on organic -N, MH3-N, (N0a + W03)-W, Total -N",
P04-P, Total -P, chlorides and conductivity.
47. The average values of the foregoing parameters differed very little from
that of the three major streams (Ward Creek, Incline Creek, and Upper
Truckee Trout Creek) previously reported and included in the Jlj
except in the forms of nitrogen making up the Total F. Generally there
was more soluble organic nitrogen and less ammonia in the over all com-
posite than in the 3-creek composite.
48. Total nitrogen in the creeks averaged about 2 times that in Lake Tahoe,
whereas phosphorus in the creeks averaged J times as great.
49- The concentration of Total nitrogen in melted snow was more than 2.5
times that in Lake Tahoe Water, while total phosphorus was about double
that in the lake.
50. Rain water showed a much higher nutrient content than melted snow. However,
snow in January 1968 showed essentially the same growth stimulating potential
as Lake Tahoe Water in flask assays. Snow samples in 1970 showed a quite
different distribution of nutrients than in 1968 with 2 to 3 times the
Total -N content. The data suggest that greater attention should be given
to meteorological conditions at times of precipitation sampling, particularly
with respect to thunderstorm activity which may fix nitrogen.
51- By procedures detailed in the report it was possible to establish rainfall-
runoff relationships for 6l sub-basins of the Lake Tahoe Basin, including
the 31 creeks monitored by chemical analysis.
52. From rainfall-runoff relationships, estimates of evaporation, and records of
lake discharges and water levels a hydrologic inventory of the Lake Tahoe
Basin was prepared. Similarly a nutrient inventory was developed and from
the two an estimate was made of the various nutrients entering Lake Tahoe
as a result of stream flow and precipitation.
53- It was shown from data on 6 streams for which continuous flow records are
available that about two-thirds of the annual stream flow occurs in the
months of April, May, and June. However, because of the short period
(15 months) of record for 28 of the 31 streams it was considered infeasible
to weigh the nutrient data on a monthly basis instead of a simple yearly
average.
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Precipitation directly on the lake surface plus runoff from the land has
averaged 6kk,OOQ acre feet per year during the past 10 years, i.e. about
1/190 of the estimated total volume of Lake Tahoe (122 x 106 acre feet).
55. Nutrient concentration in the 6kk, 000 a.f . was approximately twice that
found in Lake Tahoe .
%. The similarity of Ward Creek water to Lake Tahoe water suggests that the
quality of lake water is about the same as the runoff from undeveloped
land, in terms of nitrogen content.
57. Creeks draining populated areas show about twice the concentration of
nutrients found in Lake Tahoe
58. From 56 and 57, plus the fact that the combination of precipitation and
surface runoff is also double that of Lake Tahoe, it is reasoned that
precipitation must have increased in nutrient load with the years . The
fact that moisture -laden air masses which lead to precipitation at Lake
Tahoe first pass over the heavily urbanized San Francisco Bay Area and the
intensively formed Central Valley lends credence to such a postulate.
59. It is concluded from a comparison of Lake Tahoe ₯ater and surface flow
plus precipitation that the latter reflects an influence of relatively
recent origin which involves a nutrient enrichment of Lake Tahoe.
60. Secondary sewage effluent from South Tahoe used in pond assay studies
averaged about 190 times as rich in Total nitrogen as was Lake Tahoe,
and 87 times as rich as the combined stream flow and precipitation. For
tertiary sewage effluent the corresponding factors were Il4 and 52,
respectively-
6l. From the assumption that domestic sewage flow is 100 gallons per person
per day and that the nitrogen content of secondary sewage is that observed
at South Lake Tahoe (27 mg/i),the 6^4,000 acre feet from streams and
precipitation is equivalent to the secondary sewage of 66,700 people.
62. Using the same assumption as in 6l, the excess of nitrogen in stream and
precipitation over that of Lake Tahoe is equivalent to the secondary
sewage of 36,^00 people.
6j. From 6l and 62 it may be estimated that if the 1970 population of the Lake
Tahoe Basin averaged 100,000 people and all sewage had been exported about
30 percent of the man generated nitrogen in the basin would have still gone
into Lake Tahoe .
6^. Taking into consideration the relative crudity of some of the data, and
the many subtleties which are overlooked in the foregoing estimates, it
seems certain that every effort must be made to limit the flow of nutrients
into Lake Tahoe . Both what we know and what we do not know support this
conclusion.
65. Observation of Lake Tahoe and its biota by Dr. James E. Lackey in April 1970
led him to suggest that
a. Even such a lake as Tahoe should now and then develop algal growths
dense enough to change turbidity in the top 10 meters.
b. Tahoe has undoubtedly for years produced an algal crop in the spring;
March being indicated by project reports (3).
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c. Tahoe should at all times have a standing crop with a several-fold
seasonal increase.
d. Disturbance of the waterfront should be strictly limited.
e. Use of tributary streams by human population should be watched.
f. A luxuriant growth of Ulothrix was observed in the Truckee River
fed on lake water, hence the lake evidently has the potential to
support a heavy algal growth at times. Why such has not been reported
is an unexplained question.
66. Long term studies of the biota and the limnology of Lake Tahoe are needed
along with a thorough evaluation of what has already been done.
6? In spite of the difficulty of extrapolating pilot pond and laboratory
findings to field 'conditions the findings of the study clearly indicate
that man's activities in the Tahoe Basin should be subject to controls
not common in less obviously critical situations.
68. For the protection of surface waters in general,, and of Lake Tahoe in
particular it is concluded that the historic right of men to use land
may have to be infringed upon to an extent not envisioned in existing
law and local zoning ordinances.
Auxiliary Studies
69- Chemostat (continuous flow) assays, such as used in pond ass ays, could
not be made to perform on a laboratory scale at the low levels of
nutrient concentration prevailing at Lake Tahoe with sufficient reliability
for purposes of the project.
70. The objectives of the project did not permit the time and research
necessary to develop the chemostat as a laboratory assay method,
despite its theoretical advantages over the flask method.
71. Studies of the kinetics of algal growth did not reveal whether the
crudity of data near the lower :limit of the resolving power of
chemical analyses} or the applicability of the Michaelis-Menton
model to algal systems,, were responsible for disappointing results
of kinetic analyses made (l, 2, 3) during the study.
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SECTION II
RECOMMENDATIONS
On the basis of the findings herein reported, the unevaluated factors cited,
the areas where knowledge is known to be insufficient, and the current eagerness
of citizen groups and public agencies to be about environment-related activities, it
is recommended that:
1. The program of monitoring of creeks be continued, with the objective of
definitely establishing the relationship of man's activities to water
quality as a basis for:
a. Formulating appropriate means of control.
b. Establishing relationships through which a minimal program of
monitoring might reflect the overall changes taking place in
the Basin.
2. A systematic program of chemical analysis and algal growth potential
assay of precipitation be initiated and conducted over a period of
years for the purpose of isolating and evaluating it as an important
source of nutrient inputs to Lake Tahoe.
3. The program of investigating the amount of sediment recycling in
Lake Tahoe, identifying and controlling its source, and evaluating
its aesthetic and limnological effects be continued and expanded.
h. A survey be made to discover the scope and nature of the numerous private
and public studies presently under way in the Lake Tahoe Basin.
5. An appropriate task force, or study team, be set up to evaluate on an
annual basis the aggregate findings of the numerous ongoing studies in
terms of water quality, eutrophication potential, sources of pollutants,
environmental effects, legislature needs, and other objectives of
society; particularly in the water quality context.
6. Although not related to eutrophication at current levels, the effect
on the quality of Lake Tahoe by chlorides used in pavements de-icing
should be evaluated.
11
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SECTION III
RESULTS OF STUDY
CHAPTER I
INTRODUCTION
NEED FOR STUDY
The study herein reported was initiated in 1966 pursuant to a need which
derived from two major considerations: l) a decline in quality of surface waters
in the United States despite the dedicated efforts of pollution control agencies,
and 2) the desire of millions of citizens to preserve the clarity of Lake Tahoe
for aesthetic reasons. Although the nutrient-rich condition which characterizes
eutrophication is "by no means the only problem of surface water quality, the two
foregoing considerations differ in this particular only in order of magnitude of
the associated problem. Since 1966 the concern for both water quality in general
and for Lake Tahoe in particular has increased in intensity as the public has
become alarmed and man is increasingly assigned the role of villian in environ-
mental matters. Similarly, the accelerated efforts of public agencies to put an
end to water pollution has increased the urgency for knowledge of the factors which
trigger eutrophication of surface waters and of the means by which they may be
overcome.
In the general case of surface waters, eutrophication is not always the
result of man's activities. Occasionally lakes, ponds, and streams even under
wilderness conditions receive sufficient nutrients from plant and animal residues
to support a rich flora and fauna. In the more common situation, however, to
which this study is directed, nutrient concentrations are initially low enough
that the water is well suited to such high levels of use as domestic water supply,
while at the same time supporting a good fish fauna and the food chain on which it
depends. Here the source of nutrients is degradation of rocks and the decay of
organic matter washed in from land surfaces or blown in from bordering vegetation
and, generally, recycled within the water itself. Such a natural equilibrium is
disturbed when man diverts water and returns it with the burden of biochemically
unstable organic wastes from human life processes. A critical situation develops
when the number and concentration of people, or when a combination of human numbers,
industrial activity, land fertilization, concentration of livestock, disturbance of
natural cover, and so on, produces nutrients at a level which overfertilizes natural
waters. Such highly eutrophic waters are objectionable to man because the excess
aquatic growth that develops in such an environment renders them aesthetically
unattractive or otherwise unsuited to beneficial use.
Throughout the United States the percentage of the water resource which
has eutrophic characteristics has grown rapidly in recent years as both the on-
shore and water using activities of man, as well as his numbers, have multiplied.
Green scums, hairlike filaments on shoreline rocks, and shallows clogged with weeds
have increasingly appeared in waters formerly free of such nuisance. Algal blooms
have aroused public indignation and have increased the cost of obtaining satisfac-
tory water. In severe cases they have limited the use of surface waters and so
impoverished the lives of recreationists and brought financial disaster to sectors
of the recreational industry. To combat the loss of water quality and its social
and economic effects, regulatory agencies have enunciated stricter water quality
criteria, standards, and regulations intended to preclude the discharge of growth
stimulating factors into receiving waters.
The specific situation in which there is a need to evaluate the applicability
to Lake/ Tahoe of measures generally suited to the control of eutrophication, exists
because the lake is unlike anything generally found in the world. Its water is
exceptionally low in phosphorus, nitrogen, and other growth stimulating factors. It
is deep, well mixed, and water temperatures are low due to altitude and the snowmelt
which feeds it. The lake occupies a large percentage of the Lake Tahoe Basin;
13
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consequently water export must "be limited if the integrity of the lake is to "be
maintained. Finally, no one knows the exact degree to which nutrient enrichment of
the lake is reduced "by export of sewage effluents; the measures necessary to permi*
retention of waste waters in the basin; or the precise percentage increase in natural
fertilization of the lake resulting from human activities. Moreover, the lake is
under extremely heavy population pressure with attendant motivation to develop shore-
line facilities and a regional economy along'accustomed patterns in which unique
environmental aspects are not so important a factor.
But what are the growth stimulating materials that lead to eutrophication;
what is their origin; and in what concentrations are they significant? The need for
study is related to all three aspects of this question.
The obvious source of nutrients is effluent discharged as municipal, agri-
cultural, and industrial waste water. First attention to such wastes, however, was
logically directed in the past to its oxygen demanding properties (BOD) and to their
deleterious effect on aquatic life and on the aesthetic quality of water which
various other "beneficial uses require. Consequently, the art of sewage treatment
developed around "biostabilization of degradable organic matter and until quite
recently treatment processes have become progressively more sophisticated only in
their ability to oxidize organic matter. Unfortunately, the oxidized forms of
nitrogen and phosphorus are in themselves significant growth stimulants, and their
presence in waste water, along with biosynthesized vitamins, amino acids, trace
elements, and other growth factors found in biologically treated wastes, raises
serious questions as to the suitability of conventional waste treatment for control
of nutrients influencing eutrophication.
In response to these questions the concept of nutrient removal from sewage
effluent has recently had widespread appeal in water quality management. Because a
few of the blue-green algae, one of the most important representatives of nuisance
algal blooms, can fix nitrogen from the atmosphere, and because of the increasing
quantities of nitrogen in rain, it is widely suggested that phosphorus is the criti-
cal nutrient and should "be the first to be removed from sewage effluents. Nitrogen
and phosphorus removal has been advocated and is already being practiced in the
South Lake Tahoe area.
There is, therefore, a need to determine several factors in relation to
sewage effluents, including:
1. The concentrations at which nitrogen and phosphorus will trigger or
support serious algal growth.
2. The algal growth stimulating effect of sewage from which nitrogen and
phosphorus has been removed.
3. The ability of practical nutrient removal processes to reduce nitrogen
and phosphorus to levels below that critical to algal growth.
The assumption that domestic and industrial waste water effluents are the
principal source of nutrients is not necessarily valid. In many instances in the
lake country of the middle west fertilizing of agricultural land and animal manure
disposal practices are the critical factors in eutrophication of lakes. On every
hand the activities of agriculture, the development of housing subdivisions, highway
construction and similar works disturb the natural ground cover and by dis-
rupting the equilibria of natural systems render the surface more subject to erosion.
Pavement, roof areas, land drainage, storm sewers, and straightening and lining of
stream channels hasten the delivery of surface wash to receiving waters. Consequently
there is a need to evaluate the relative role of sewage effluents and other sources
of nutrients in the stimulation of algal growth in surface waters.~~""~
Such a need is especially important in the Lake Tahoe area where the basin
is forested, population is burgeoning, and land use encourages erosion by following
the same pattern as other urban developments. Export of sewage effluents from the
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"basin is well advanced "both in practice and in planning for the future. Therefore
"both the need and the opportunity exists to study such aspects of the problem as:
1. The residual ability of nutrient-stripped (tertiary) sewage effluents
to stimulate algal growth.
2. The ultimate fate of nutrients removed from sewage in the Tahoe Basin.
3. The overall amount of nutrients reaching Lake Tahoe annually from the
normal processes of nature in the basin, including precipitation.
k. The effect of man's near-shore and shoreline modifications and activi-
ties on the biology and natural beauty of the Lake.
5. The significance of findings of laboratory and pond assays in terms of
the overall complex limnological system which is Lake Tahoe.
In relation to the foregoing needs it has been suggested that it would be
particularly ironical and tragic if the nitrogen stripped from sewage found its
way into the lake via rainfall and phosphate via pickup from landfill, while the
purified water from which they were removed was needlessly exported from the basin.
Although it has not been shown that such is the case, the speculation underscores
the need for studies of the type herein reported.
Because shoreline development and construction may influence both the input
of nutrients and the way the lake responds to them, there is a need to interpret
the results of assays in relation to:
1. Development of flood plains, meadows, and marshlands.
2. Construction of marinas, lagoons, and breakwaters.
3. General construction practices throughout the watershed.
OBJECTIVES OF STUDY
The general objectives of the study are implicit in the need outlined in the
preceding section. Specific objectives include:
1. To determine, by the most effective laboratory bioassay techniques
available, whether there is present in effluents from waste water
treatment processes, or in surface wash or groundwater seepage from
inhabited or uninhabited areas, materials capable of stimulating
algal growth in surface waters; and at which concentration they may
be significant.
2. To demonstrate by studies on artificial ponds the applicability to
Lake Tahoe of the results of laboratory assays or possible inputs
to the lake.
3. To evaluate the danger to Lake Tahoe of man's waste effluents and
land practices in the basin, on the basis of results of studies in
pilot-scale experimental ponds and a survey of the various nutrient
sources within the basin.
k. To compare the growth stimulating characteristics of tertiary
effluent in Lake Tahoe water with that of the same effluent when
ponded in Indian Creek Reservoir. (Supplemented by Demonstration
Grant No. 16010 DNY.)
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5. To prepare an authoritative document (Final Report) on eutrophication
of surface waters based on the findings of the study throughout its
total grant period and current knowledge of the problem at the time
of reporting.
NATURE AND SCOPE OF REPORT
As noted in the Preface, the report herein presented is of the nature of a
Final Report covering five years of study of the eutrophication of surface waters
with special reference to Lake Tahoe. It is concerned primarily with previously
completed and reported [1,2,3] work pursuant to the first and second objectives
(above); with both previously reported and new findings pertinent to objective
number three; and with data evaluation pertinent to the fifth objective. Results
of study related to the fourth objective, for which a supplementary grant (Demon-
stration Grant No. 16010 DNY) has been made to the Lake Tahoe Area Council by the
Federal Water Quality Administration, are reported separately in previous [k] and
forthcoming reports on Indian Creek Reservoir.
No single theoretical consideration characterizes the approach to the study.
Consequently scientific theory is introduced in the report only when it seems
necessary to an understanding of the subject matter under discussion. The overall
intent was to discover the significant sources of nutrient enrichment of surface
waters and to demonstrate their importance in the rate of eutrophication of Lake
Tahoe. The study procedure was first to select from available assay and analytical
methods those best suited to measuring nutrients at the low concentration levels
known to exist in Lake Tahoe. Next, assays were made by the selected techniques
of a wide variety of waste water effluents and of surface, ground, and meteorologi-
cal waters which might transport nutrients into any body of surface water, regardless
of whether or not they presently represent known discharges into Lake Tahoe. From an
analysis of the results of this second phase of the study it was determined which of
the possible sources of nutrients might profitably be further investigated in pilot
plants. Pilot plant studies were then conducted to explore the potential of selected
wastes to trigger algal blooms in Lake Tahoe water, and at what concentrations a
significant effect might occur. Finally, the emphasis of the study was directed to
an estimate of the amount of nutrients generated in the Lake Tahoe Basin and dis-
charged to the lake as a result of a combination of natural cycles and man's presence
and activities in the basin.
Although many of the several phases of the project proceeded simultaneously
at some stage of the study the report is divided into a series of chapters related
to the objectives in the sequence noted in the preceding section. Specifically:
1. Chapter II reports the problems and conclusions relative to assay
techniques and analytical methods.
2. Chapter III reports the evaluation of sources of possible nutrient
enrichment of Lake Tahoe.
3. Chapter IV deals with pilot pond assays of Lake Tahoe water from
which might be predicted the effect of various concentrations of
waste water in the shallow portions of the lake.
4. Chapter V presents data and estimates of the nutrients contributed
to Lake Tahoe by surface runoff from various types of land use,
precipitation, etc.
5. Chapter VI compares the observed nutrient content of Lake Tahoe
water with the estimated content and evaluates the potential of man's
occupancy of the Basin to accelerate eutrophication of the lake.
6. Chapters VII and VIII present an overall evaluation of the study in
terms of eutrophication of surface waters, and summarize the conclu-
sions and recommendations which the study supports.
16
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CHAPTER II
ASSAY TECHNIQUES
INTRODUCTION
The first of the five objectives listed in Chapter I require "both the selec-
tion of available methods of biological and chemical assay best suited to the study,
and their application to a variety of possible influents which might transport sig-
nificant concentrations of nutrients into surface waters. In the interests of
clarity these two aspects of objective number one are herein discussed in separate
chapters. Chapter II is concerned with the rationale and the experimental results
which led to the adoption of particular methods, and with the details of the methods
themselves. Application of the techniques to achieve the second aspect of objective
one is the subject of Chapter III. Further details of the assay techniques are
added as appropriate to an understanding of procedures and results throughout the
report.
BIOASSAY TECHNIQUES
General Considerations
The concept that the capability of a waste water discharge to hasten the
eutrophication of a receiving water might be measured on either an absolute or a
relative scale by some method of bioassay has long intrigued researchers and regu-
latory officials. After a number of years of study of the factors affecting algal
growth, Oswald [5,6] suggested the term Algal Growth Potential and defined it as the
"weight of algae which will grow at the expense of algal nutrients in a water when
no factor other than nutrient is limiting to growth." Two basic methods which might
be used for such bioassays have long been used in various chemical and biological
industries and in research. They are the batch and the continuous flow processes.
As a bioassay procedure the first involves flask assays; the second depends upon the
use of devices commonly known as "chemostats." Both methods were used in the study
herein reported for reasons and purposes noted in the appropriate context.
Flask Assay
The flask assay depends upon culturing a selected test organism in a medium
containing the waste water to be assayed over a range of concentrations and under
standard conditions of lighting, temperature, and mixing. Algal growth is then
measured in one or another manner and the result related to the concentration of the
growth-limiting factor or nutrient. Although subject to limitations discussed in a
subsequent section of this chapter, flask cultures have been widely used in the field
of biology and accumulated experience suggested it as a method suited to the purposes
of the study unless parallel findings with continuous flow systems should prove
superior.
Test Organism. Tne alga Selenastrum gracile (Reinsch) was initially (1966)
selected and utilized as a test organism on the basis of consideration of the
characteristics of an ideal test organism [1] and of favorable results reported by
Skulberg [7] with the same genus. It has the disadvantage of producing large cells
under nutrient rich conditions, thus making it difficult to establish a relationship
between cell count and biomass. In addition, newly formed cells tend to remain
attached, but because they rarely exceed four in a group, cells are easily distin-
guished by "hand" counting under the microscope. These limitations, however, were
17
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considered minor for the nutrient-poor conditions prevailing in the Tahoe situation
as long as the hand counting method was used. In July 1969 machine counting by use
of the Coulter counter was initiated. Because this instrument records as a single
particle any colony of cells passing "between its electrodes the test organism was
changed to Selena strum capricornutum, which has similar characteristics to S_._ gracile
but does not tend to clump.
With either of the two species of Selena strum a "basic culture was maintained
at a constant growth rate by the continuous flow culture method, using a residence
time, Q, of 5 days and a nutrient solution of Skulberg's medium (Appendix A), which
is specially designed for culturing Selenastrum. The purity of this basic culture
was verified periodically by microscopic examination.
Assay Procedure. In making a flask assay of any nutrient source, the sample
to be assayed was first filtered to remove any organisms which might compete with
the test alga for nutrients, and any debris which might be mistaken for organisms by
the counter. The sample was then diluted to the desired concentration with filtered
Lake Tahoe Water (LTW) and 150 n£ placed in each of 5 sterile 250 m0 Erlenmeyer
flasks. Cells of the test alga in good physiological condition were centrifuged and
washed twice with LTW to minimize the chance of nutrient carry over from the stock
culture to the assay flasks. An equal volume of the washed suspended cells was then
added to each test flask in the amount needed to introduce approximately 50 cells/mm3
into the 150 m£ of liquid.
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/minute) shaker table for a period of 5 days. Illumina-
tion of approximately 550 ft-c (5920 lux) intensity was provided by four ko watt
G. E. fluorescent lamps, No. F^O-CW, Coolwhite, four feet in length. A typical flask
assay used in the study is shown in Figure 2-1.
FIGURE 2-1 TYPICAL FLASK (AND CHEMOSTAT) ASSAY
APPARATUS USED IN STUDY
Cell concentration in the test flasks was determined by cell counts at the
end of one, three, and five days, preliminary tests having shown the maximum cell
growth rate to be attained within that period. For hand counting under the
18
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microscope, a 10 m£ 'aliquot was removed from each flask after 1, 3, and 5 days of
incubation. 'This aliquot was then centrifuged for 10-15 min at 2000 rpm (approxi-
mately 800 times gravity). After centrifugation, 8-9 mtf of the supernatant were
removed with a Pasteur pipette and the pellet of cells resuspended in the remaining
liquid medium. A drop of the suspension 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 concentration 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 fcJL
aliquot from each flask. The aliquot was then diluted with a saline solution so
that the final concentration ranged from a maximum of 50 percent to that concentration
which provided a final count of less than 10,000 particles (counting capacity of the
Coulter counter) for a 0.5^ diluted sample. As in the case of the hand count
method, a mean value was obtained for the five replicates.
Continuous Flow Assay
The continuous flow assay involves culturing a single alga or group of
organisms in a chemostat under standard conditions of lighting and temperature and
under steady state conditions of nutrient input and algal cell production. The
concentration of algal cells in such a system is thus a function of the concentration
of the growth-limiting nutrient or growth stimulating factor in the water assayed.
Chemostat. A typical laboratory scale (one liter) chemostat used in the
study is shown in Figure 2-1. Each unit was cabinet mounted and illuminated, with
two JO watt G. E. Coolwhite fluorescent lamps No. JOTS-CW,, providing 200-250 ft-c
(2150 to 2700 lux) light intensity. A small Dyna pump (not shown in the figure)
discharged air through a sterile cotton filled tube into the base of the chemostat
at a rate sufficient to maintain a slow rise of bubbles through the liquid. This
served to keep the algal cells in suspension and to disperse influent water to be
assayed. This latter was injected into the chemostat by a small Sigmamotor pump
through a wye in the air influent line. Displaced liquid was collected from an
overflow tube at the top of the unit. The entire assembly was installed in a 20°C
constant temperature room.
Assay Procedure. In making a continuous flow assay the chemostat was first
filled with the sample to be assayed. It was then inoculated with the test alga
(S. gracile) at a concentration level of 20 to 50 cells/mm3. The sample was then
fed in at a continuous rate sufficient to provide the desired residence time
(normally 5 days) and cell concentration in the overflow was determined by cell
counts at two day intervals. When 3 successive counts checked within + 20 percent
with no indicated trend, the system was assumed to be at steady state. Thereafter
data were taken for at least two additional residence periods. To develop data for
kinetic constant evaluation, at least 3 different residence times, 0, were made
within a 5 "to 15-day range.
Expression of Results
There are several ways to express the results of bioassays. One is the
maximum cell concentration, X, reached by an organism in a specific time period.
For example, the 5-day concentration of S^ gracile in flask assays at Lake Tahoe
was designated as $5 and is herein reported as number of individual cells/mm3. In
situations where the individual cells are of a single genus and of relatively uniform
size, the relationship between cell count and biomass is readily determined by simple
experimental parameters.
19
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In flask assays the concentration of cells, X, is not a straight line
function of time because of depletion of nutrient, intra-culture competition for.
food, and the varying nutrient requirements of cells of different ages. In the
continuous flow system, however, where cells are of constant age and where both
nutrient depletion and cell concentration are at steady state, X might be a good
measure of the potential of any given nutrient concentration to support algal
growth, but different values of X5 are to be expected in flask and continuous flow-
assays of the same water with the same test alga. In either case maximum growth
rate might be a preferable measure of algal response to the growth stimulating
factor in the assayed water.
X
O
z
O
O
W
u
O
O
O
£
O
O
H
£
W
II
tf
H
P
£
co
TIME, days
FIGURE 2-2
TYPICAL MICROBIOLOGICAL
GROWTH CURVE, FLASK
Figure 2-2 shows typical growth rates and nutrient depletion curves for
flask culture of microbial systems. Experiment has shown that the same situation
applies to algal cultures. When the concern for nutrient concentration present in
the environment is its effect on growth rates of specific algae, as in the case of
algal blooms resulting from eutrophic conditions, most observers suggest that the
maximum rate of growth is a better measure of algal response than is cell concen-
tration. This measure is designated as j}, and represents the steepest slope of all
possible tangents to the cell concentration curve plotted from periodic cell counts
by microscopic examination, Coulter counter, or other means. For the batch method,
or flask assay, the symbol is given the subscript b, i.e., jj, represents the maximum
growth rate in a flask assay (batch type reactor).
^
l_i is expressed as percentage increase in cells per unit of time. Thus, for
example, ^ = 0.2^ days * means that in a particular flask assay the maximum rate
of cell increase was 25 percent per day.
Maximum growth rate may be computed by a regression analysis of cell counts
versus time, preferably by the use of a computer. This measure is herein designated
as ^^ for flask assays, or in general, j^. It is expressed in the same units as
jl . In some experiments previously reported [2] by the authors, ja-^ showed a some-
what higher statistical significance than j^, probably because of the mathematical
precision of its computation.
Another method of measuring the results of bioassay is to measure the
reduction in concentration of added C14 in a culture as a result of algal growth,
and to relate it to biomass on the basis of the "normal carbon content of algal cells.
It has the advantage of reducing the time necessary for cell counting by hand but
20
-------
does not exceed the 13 seconds per count attained in the study by the Coulter
Counter.
Finally, the increase in volatile suspended solids (VSS) during a period of
incubation can be used to measure the growth response of organisms to nutrient
sources. It is essentially the only practical way to assess the response of a
heterogeneous mixed population of organisms such as exist under natural field
conditions.
INTERPRETATION OF RESULTS
Interpretation of the results of flask and continuous flow bioassays involve
two principal factors:
1. The limitations, both practical and theoretical, of the tests
themselves, and
2. The ability of laboratory tests to reflect actual response of
organisms in natural environments.
Each of these factors is the subject of continuing scientific study,
speculation, and disagreement far beyond the scope of this report. Therefore in
this, and the section immediately following, the attempt is to summarize those
considerations especially pertinent to an evaluation of the results of the study
in terms of its stated objectives (Chapter I).
Theoretical Considerations
In the interest of eutrophication control it is highly desirable that growth
rate be predictable on the basis of analytical measurements of the nutrient present
in any water sample because the rate of growth of specific algae may be the key to
objectional algal blooms. One major advantage of a continuous steady state assay
method is that it permits the determination under laboratory conditions of the level
of standing crop of any organism that can be supported in a particular hydraulic
system at a specified residence (detention) time by some known concentration of
nutrient.
Working with microorganisms rather than algae it has been shown by
Michaelis-Menten [8], Monod [9], Caperon [10], Maddux [11], Williams [12],
Jannasch [13], Dugdale [lM, Pearson [15]; and others that the specific growth
rate is a first-order or first-zero order (Michaelis-Menten) function of the
u S
substrate (nutrient) concentration. That is, \JL = kS or p. = ^ . When the final
IV ~T" b
S
value of S (Figure 2-2) =0, i.e., Si = 0, as at low levels of initial rate limiting
nutrient (So), a cell continuity and a kinetic equation can be developed [2] which
takes the following forms:
1 Y(SQ sl)
g- = u - kd = Yd - kd = - 2_
and
i-i-^/i\ + ±
n ii " £ \sll 5 (2)
In which:
21
-------
q = specific nutrient removal velocity
gms nutrient removed
gms cells - day
^ /gms cells produced^ . -i
H = specific growth rate \* gm cellB _ day ) > tlme
S = influent concentration of rate limiting nutrient
o
B! = concentration of rate limiting nutrient in the reaction system
Xj_ = concentration of cells in reaction system
0 = hydraulic residence time of system, i.e., 0 = V/F
cellular residence time (i.e., mean cell age in system)
c
= net cellular growth rate
&
c .
/gms cells destroyed'
kd = specific decay rate, i.e., ( gm cells _ day,
Y
/gms cell produced \
yield coefficient, i.e., f nutrlent removedj
i
p. = maximum specific growth rate, time
K = nutrient concentration at one-half the maximum specific growth
rate, mass per unit volume.
To determine the rate constants and coefficients in Equations 1 and 2 a
computer program can "be prepared to analyze the effect of various nutrients
found by chemical analysis during flask or continuous flow assays. The benefits to
be derived from such analysis of a continuous flow system and its application to
eutrophication problems, provided the equations apply to algal systems as effectively
as to microbial cultures, are as follows:
1. A given level of rate limiting nutrient (i.e., S1 = N03, P0~, etc.)
in the receiving water determines the specific growth rate, |_i, that
can be supported by that rate limiting concentration [i.e., |_i = f(S )].
2. For a given level of S and p. and yield coefficient, Y, the mean cell
concentration, X , (standing crop) is determined by the residence
time for the system:
Y(B - S )
X - ° 1
~
^>. The net or gross cellular growth rate that will follow from any level
of nutrient concentration can be estimated once the rate constants and
coefficients have been determined for the organism and nutrient from
the relationship:
f = » - kd
Limitations of Bioassay Techniques
A major limitation in applying the results of either flask or continuous
flow assays to field conditions is the fact that at best they represent simple
ecosystems rather than the complex systems of nature in which predators, competitors,
and parasites live in some dynamic balance subjected to seasonal and numerous other
environmental factors which often permit one or another species to predominate
periodically. Moreover, even a single test alga in a protected simple system responds
in different ways when environmental and nutritional changes occur. The flask assay
22
-------
has the additional drawback that at its inception cells of the test alga in the log
phase of growth have a wealth of food, whereas at the end of the assay nutrients
are depleted and cells at all stages of growth and having a wide range of nutritional
requirements are living in their own wastes amid their dead and decaying ancestors.
On the other hand, the assay requires little time, equipment, or operational skill.
If growth of the test alga is stimulated by any concentration of nutrients it is
evidence that the material assayed did indeed have a potential to accelerate.eutro-
phication of receiving waters although a numerical value of this potential under
field conditions may not be assignable. However, at the very low concentrations
of nutrients present in Lake Tahoe, failure of a flask assay of lake water to produce
growth does not necessarily mean that the lake is unproductive of algae at some
limited level.
The continuous flow assay overcomes the competition within a species by
maintaining a population of a relatively uniform age and in the log phase of growth.
Beyond that it shares the limitations of all simple ecosystems plus the added
difficulty of maintaining steady state conditions at a laboratory scale of apparatus;
and a longer time requirement because of the necessity to achieve a steady state.
Most serious, perhaps, during the period of study herein reported was the problem
of making the results of assays and the assumed kinetic model 'sufficiently compatible
to permit taking advantage of the three benefits of a kinetic model cited in the
preceding section.
CHEMICAL ASSAY METHODS
Chemical and related analyses necessary to the objectives of the study are
listed in the various chapters and in related appendix material. The particular
problem initially was that of selecting or adopting methods of analysis sufficiently
sensitive to detect significant changes in the low concentrations of nutrient
compounds present in Lake Tahoe and in some of its tributary waters.
Preparation of Samples
Preliminary preparation of samples for physical and chemical analyses varied
somewhat depending on the specific method chosen for each assay. Samples selected
for flask culture, including Lake Tahoe water used for dilution, were filtered
through Whatman glass fiber .filter pads (GF/C) and finally through HA Millipore(R)
filters (OA5 M. pore size). They were then stored in tightly covered polyethylene
containers and frozen, unless the test was to begin within five days. Due to the
large quantity of water required for pond studies, sewage effluents used in the
continuous flow pond assays were not filtered.
Aliquots of the samples, both the unfiltered and those passed through the
previously described glass fiber and millipore filters, were analyzed chemically
for a number of constituents. Samples were kept in tightly capped 2-& polyethylene
containers and stored in a refrigerator at temperatures approaching 0°C until all
chemical determinations were completed. Glassware employed in conjunction with the
assay was dry heat sterilized.
Analytical Procedures
Chemical analyses were made according to Standard Methods [l6] in determining
biochemical oxygen demand (BOD), chemical oxygen demand (COD), pH, alkalinity,
ammonia, chlorides, and conductivity. Methods described by Strickland and Parsons
[17] were considered more suitable for iron, nitrite, nitrate, and reactive inorganic
phosphorus at the low concentrations prevailing in the Tahoe samples. Similarly,
procedures recommended by Jenkins [18], were found more appropriate for soluble
organic phosphorus and soluble organic nitrogen. Details of individual analyses
are presented in Appendix A.
23
-------
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 Fl6]; Strickland and Parsons [1?]; and Maciolek [19]. Whatman glass filters
(GF/C) were used in solids separation. The filters were prepared by soaking in
distilled water to wash the fibers free of salts. They were then placed in a muffle
furnace for 30 minutes at ^50°C to destroy any organic matter present without fusing
the glass fibers. After cooling, the filters were dried in a hot air oven at 75 °c
and tared quickly on a Mettler semimicro "balance, to avoid error due to the extremely
hydroscopic nature of the dried filter. In making the solids determinations the
sample was applied to the filter until the volume had passed through or until the
filter was completely clogged. The volume of filtrate was noted. The filter pads
with their load of suspended solids were dried overnight at 75 °C and the dry weight
recorded to the nearest 0.01 mg. They were then saved for further analyses by
placing them in marked envelopes and stored in a refrigerator freezer. Samples in
which the VSS value was desired were redried and reweighed to verify the suspended
solids value. Thereafter the filters were ignited at 550°C for 2 hours, soaked with
a few drops of distilled water to rehydrate the mineral matter, dried overnight at
75°C, and weighed. The difference between the SS weight and the weight after
ignition was then used to determine the VSS in mg/#.
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 concentration
encountered in the various samples assayed. The procedure was to prepare two standard
curves for the Beckman Model B speetrophotometer, one using a 1-cm pathway cuvette
and the other a ^-cm cuvette. The range of concentration using the two pathway cells
was from 1 |ag/g to 200 yg/&. 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.
EVALUATION OF ASSAY TECHNIQUES
Bioassays
Preliminary flask assays were run to determine the appropriate period of
assay necessary to insure that the maximum growth rate was achieved. Using 1$, lOfo,
and 50/o concentrations of various sewage effluents, it was found [1] that the percent
of assays showing a maximum value of ja^ (maximum growth rate) within 3 days was 6k,
73, and 63 percent, respectively. All reached a maximum value within 5 days. In
analyzing Lake Tahoe water alone, with added nitrogen, and with added nitrogen and
phosphorus, the percent reaching maximum growth within 3 days was 66, 78, and 53
percent, respectively. Of some 300 experiments, all reached the maximum rate within
5 days.
Studies were made [1] of possible error in converting cell size of S. gracile
to biomass. Volume of individual cells were related to cell size by measurement of
the length and breadth of numerous cells with an ocular micrometer and assuming that
the geometry of the cell was described by two cones connected base to base. Cells
were found to be relatively uniform in volume, predominantly about 75 p.3, although
the variation ranged from 50 to 150 u3. Assuming, on the basis of packed cell
volume experiments and information on other types of algae, that cells of S. gracile
have a specific gravity of 1.15, cell volume was converted to mass. ~~
No parallel experiments with chemostats were possible prior to the beginning
of assays of the various influents to the lake (Chapter III) because of the time
factor and the long period required to master the chemostat technique in a situation
where extremely low concentrations of nutrients make it all but impossible to achieve
and maintain steady state conditions.
2k
-------
Chemical Analyses
Early, attention was directed to establishing reliable results from the
chemical laboratory. All chemical determinations were subjected to replicate
analysis on aliquots of the same sample to determine the precision attainable by
the project staff and the analytical procedures used under the conditions prevailing
at Lake Tahoe. The results showed that with the exception of organic nitrogen and
total phosphorus in Lake Tahoe water, where concentrations are extremely small, the
chemical work was of good accuracy as measured by the coefficient of variation of
results. Wild values appeared occasionally but their effect was minimized by the
great number of analyses made in the course of any particular study. Techniques
and accuracies soon became quite refined and reliable. A statistical analysis of
the two methods of filtration in the laboratory (0.^4-5 ^ HA Millipore and GF/C
Whatman glass fiber paper) indicated that there is no essential difference in the
accuracy of the two methods.
Carbon1
Experiments with C1 were made to determine whether tracer techniques might
speed up the work by eliminating counting of cells under the microscope. Although
other workers had reported good results with this technique no reliable procedure
could be established, even with their assistance, hence the possibility of tracer
methods was abandoned early in the project. This does not mean that the method is
unsuitable but that the timing and the objectives of the project precluded a program
of research on the application of the C1* technique to the immediate needs.
RESULTS
From theoretical considerations, consultation with knowledgeable biologists
and limnologists, practical factors, and the results of preliminary experiments it
was decided to approach the study basically in the following manner:
1. Utilize flask assays in evaluating the algal growth response in
studies of
a) Lake Tahoe water, alone and with added nutrients
b) Miscellaneous sources of nutrients
c) Effluent from pilot ponds
d) Monitoring of creeks.
2. Run chemostat assays in parallel with initial flask assays so that
the method might be adopted without loss of data should it prove
feasible.
,-N
J. Report results of bioassays in terms of cell count, X, and growth
rates jl and jl^.
k. Make statistical analyses of results to determine which measure of
growth stimulation is most appropriate.
5. Analyze all data by cell concentration and kinetic equations to
evaluate its conformity to the Michaelis-Menten model.
6. Operate pilot ponds as large continuous flow assay systems,
using a test alga or test algae.
7- Apply pilot pond assays to such possible influents to surface waters
as might prove significant in initial flask assay surveys.
-------
CHAPTER III
SURVEY OF WATERS IN THE LAKE TAHOE AREA
INTRODUCTION
Pursuant to the second aspect of objective number one (Chapter I), flask
assays were made to determine the effect of water from each of 15 different possible
sources of nutrients in Lake Tahoe. Assays of Lake Tahoe Water (LTW) provided a
background for interpretation of results. Other samples to be assayed were diluted
with LTW to reduce their concentration to 1, 10, and 50 percent of the original.
Duplicate assays were made with and without added inorganic nutrients. The results,
presented in detail in a previous report [1] are hereinafter condensed and summarized
to present their essential conclusions.
FLASK ASSAYS
Lake Tahoe Water
The growth response of S._ gracile in LTW with and without added phosphate or
nitrogen is summarized in Table 3-1. Although the maximum growth rate, jl , varied
considerably and the experiments reported do not permit a correlation between nutrient
concentration and growth rate, both the range and mean values of jj, showed an increase
in growth response when the nitrogen concentration was increased. For example, the
mean value of maximum growth rate increased from 29 percent/day in LTW to 86 percent/
day in LTW plus NaNO^. No such increase occurred when phosphate was added. Although
the data are admittedly rough, this supports the conclusion that Lake Tahoe is
nitrogen sensitive rather than phosphorus sensitive as are most other oligotrophic
lakes.
Other Sources (Chemical Analyses)
That most of the samples assayed were short of nitrogen in comparison to
phosphorus is evident when the N/P ratios reported in Table 3-2 are compared to the
1'T/P ratio of algal cells. Neglecting the very large value (71^) shown in the table
for septic tank seepage because of the known ability of soil to remove phosphates,
the N/P ratio of all sources assayed averaged 2.08, whereas the ratio for algal cells
is reported [20] to range from 6.9 to 18.
It should be noted that the values in Table 3-2 are reported in micrograms
per liter (ng/g) rather than in the more common mg/i to avoid decimal values at the
lower concentrations observed.
The data reported in Table 3-2 derive from a single analysis of each of the
several different sources of samples. Therefore the N and P concentrations shown
are not indicative of the long term means nor the temporal variations in nutrient
concentration in the sources assayed. A more complete chemical analysis of the
various sources assayed during the period November 1966 through December 1968 is
presented in Table B-l, Appendix B.
Other Sources (Growth Response)
Table 3-3 summarizes the mean values and range of values of maximum growth
rate, ^, observed in flask assays of 56 samples of surface runoff, rain, snow,
sewage effluents, seepage, and water confined in keys and marinas during the survey
of waters in the Lake Tahoe area.
27
-------
TABLE 3-1
MAXIMUM GROWTH RATES OF S_._ gracile IN LAKE TAHOE WATER
Alone and With Added Inorganic Nutrient Samples
Wo. of
Assays
25
17
23
21
12
Nature of Sample
Assayed
Lake Tahoe water
(LTW)
LTW plus
KH2P04 - Mg P/&
LTW plus
KN03 - MS N/,8
LTW plus
NHiCl - ng N/.0
LTW plus
NaNOa - |og N/^
Range of
Concentration
natural
surface
50- 8,800
20-12,000
20,000-20,500
6-10,000
jl-,3, days'1
Range
0.05-OA?
0.08-0.29
0.11-1.20
0.20-1.17
0.22-1.40
i^b; days"1
Mean
0.29
0.17
0.66
0.70
0.86
28
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TABLE 3-2
NITROGEN AND PHOSPHORUS CONCENTRATIONS
IN VARIOUS WATER SAMPLES
Source of Sample
Lake Tahoe Water
Oxidation ponds
Seepage from spray
irrigation field,
sewage
Oxidation ponds
Seepage from spray
irrigation field,
sewage
Seepage from septic
tank leaching field
Storm drain
Surface stream at
refuse dump
Storm drain
Raw sewage
Primary effluent
Creek waters
Primary effluent
Secondary effluent
Primary effluent
Secondary effluent
Secondary effluent
Secondary effluent
Secondary effluent
Oxidation ponds
N and P Concentrations
Hg/l as N
m3
< 5
350
30
-
150
30,000
680
110
850
7,600
23, ooo
200
ia, ooo
2,000
21,500
9,500
12,000
9,4oo
8,800
70
N03
k
8
8
5,800
107
26
25
48
< i
14
i
90
80
24,300
i
2,980
1,390
1,450
8
10
N02
3
3
5
9
5
10
6
22
< 1
15
9
k
< 1
19
520
46o
550
8
3
MgA
as P
P04
< 5
2,500
30
3,4oo
100
42
110
77
160
5,800
13,500
4o
18,000
17,600
30, 200
5,000
13,000
19,500
8,800
4,500
Average
N/P
Ratio
0.4 i
0.1k
1.14
1.71
2.62
. *
7l4
6. 46
2.08
5.31
1.30
1.70
7.36
2.28
1.49
0.71
2.60
1.07
0.58
1.00+
0.02
2.08
Value not used in calculating average.
29
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TABLE 3-3
MAXIMUM GROWTH RATES OF §._ gracile ATTAINED WITHIN 6 DAYS IN
FLASK ASSAYS OF VARIOUS SAMPLES
^"\^^ IV day 1
Source or^\^
Sample ^^^^
Meeks Creek
Ward Creek
Incline Creek
Upper Truckee -Trout
Creek
Rain
Melted snow
Storm drain
Marinas and keys
Raw sewage
Primary effluents
Secondary effluents
Tertiary effluents
Oxidation pond
Swamp seepage
Spray irrigation
filed, sewage
Leaching field,
septic tank
Surface Stream at
refuse dump
Concentration of Sample
1#
Mean
0.2k
0.2k
0.13
0.32
0.49
0.36
0.57
0.19
0.51
0.78
0.72
0.76
0.46
0.28
0.21
0.1*6
0.28
Range
0.16-0.42
0.20-0.27
0.06-0.17
O.lb-0. 48
0.4-9
0.36
0.34-0.79
0.15-0.24
0.45-0.58
0.70-0.92
0.35-1.27
0.72-0.80
0.24-0.71
0.13-0.43
0.11-0.30
0.36-0.57
0.20-0.42
10$
Mean
0.23
0.20
0.20
0.6l
0.56
0.28
0.53
0.25
0.74
1.18
0.93
1.01
0.68
0.48
0.4l
0.55
0.35
Range
0.14-0.39
0.17-0.21
0.06-0.53
0.58-0.64
0.56
0.28
0.35-0.64
0.09-0.41
0.72-0.75
0.92-1.40
0.61-1.27
0.83-1.19
0.47-1.09
0.44-0.53
0.14-0.58
0.27-1.01
0.26-0.39
50$
Mean
0.30
0.18
0.33
0.85
0.78
0.27
0.78
0.32
1.12
0.90
0.83
1.15
0.65
0.52
0.30
0.84
0.39
Range
0.20-0.45
0.13-0.20
0.14-0.67
0.74-0.96
0.78
0.27
0.54-1.04
0.30-0.34
1.08-1.15
0.60-1.07
0.36-1.53
0.93-1-37
0.44-0.88
0.41-0.63
0.17-0.54
0.64-1.14
0.28-0.45
No of
Samples
Assayed
4
4
k
2
1
1
4
4
2
3
11
2
3
2
3
3
3
-------
When the growth rates reported in Table 5-3 are compared with those observed
for Lake Tahoe water (Table 5-1), several facts are apparent. At the 1$ concentration
of sample, where the added nutrient effect should be the least, sewage effluents,
seepage from septic tank leaching fields, surface drainage from storm water, and
rain water all showed growth stimulation of S_._ gracile appreciably greater than the
0.29 (29 percent/day) reported for LTW. That this was the result of a true response
rather than of limited validity of data is evidenced by the fact that all of these
sources showed an increasing growth rate as the concentration increased to 10$ and
50$. The lone exception was storm drain water which showed no difference between 1$
and 10$ concentrations, but a very large increase when it constituted 50$ of the
sample assayed. The difference between the 1$ and 10$ rain water was small, but the
data in Table 5-5 leave no doubt that rain is an important source of nutrient
(nitrogen) in Lake Tahoe.
The melted s.iow assay (Table 3-5) did not differ from LTW in algal growth
response, although in Total N content it was about twice as concentrated as the lake
water (285 vs 140 (jg/^). In comparison with the rain water assayed, which occurred
during a thunderstorm, however, the snow had only 36$ as much nitrogen (285 vs 1030
VS./&Y, (Table B-l, Appendix B) - Subsequently, in 1970 (see Table 6-9, Chapter 6) snow
was shown to be a significant contributor of nitrogen to the lake.
It might be expected that storm drains picking up washings from streets,
roofs, paved parking areas, fertilized lawns and vegetated areas would represent a
source of nutrients in Lake Tahoe. The data show clearly that this is the case
although there is no way of determining how much is attributable to rainfall and
how much to soluble nutrients on the surfaces washed by storm water.
The data on seepage from spray irrigation used as a method of sewage effluent
disposal are worthy of particular comment. The reported observations were made at
a time when the South Tahoe Public Utility District (STPUD) was developing its water
reclamation plant and had not yet begun export of effluent from the Basin. At that
time disposal of effluent involved spray irrigation on forest land. Although direct
assay of the sewage effluents showed (Table 3-3) a marked ability to stimulate growth
of the test alga (S. gracilej, the same effluent had little effect on the seepage
from test borings in the spray irrigation area. The answer is obvious in Table 3-2
which shows both ammonia nitrogen and phosphate at low concentrations in the leachate
and high concentrations in the applied sewage effluent. The well known ability of
soil to absorb both ammonia and phosphates accounts for the reduction. A relatively
low value of nitrate nitrogen (107 MS/0 indicates that soil bacteria has not yet
had time to convert ammonia to the soluble nitrate form.
What can happen under the full potential of nitrogen in seepage from land
disposal of sewage is evident in the results observed in the septic tank leaching
field. In this case the sample was obviously taken from borings in a coarse material
which had not absorbed the ammonia and was close to the tile field itself. Algal
growth stimulation was comparable to that of secondary effluents at the 50$ concen-
tration. Although it is not likely that nitrogen would reach Lake Tahoe from septic
tank seepage in the form of ammonia, its ultimate conversion to soluble nitrates is
certain and can be expected eventually to enrich the lake via a combination of
routes:
1. Movement as soluble nitrogen in ground water directly or through
outcropping in surface streams.
2. Surface wash from decaying vegetation which grew more luxuriant
as a result of nitrogen in the ground water.
In relation to the first of these routes the time factor is a major unknown.
The second poses a more complex question: the time factor, the extent to which
nitrogen is recycled to the atmosphere by vegetation, and the percentage of such
nitrogen that might be returned to the lake via rainfall. Nevertheless, the data
show that septic tank leachate has the potential to stimulate algal growth in Lake
Tahoe.
31
-------
From Tables 3-2 and 3-3 it is evident that the surface stream at the refuse_
dump -was not particularly different than creek vaters in nutrients, suggesting
therefore that leaching might not have "been occurring at the time of sampling. On
the other hand the original data (l) showed organic nitrogen at 900 |_ig/8 downstream
from the refuse dump and only 350 Mg/2 upstream from it. Ammonia likewise doubled
(50 to 110 iag/0 ) in passing the dump site. Later data obtained in 1970., after
heavy frost (may have damaged the fill structure) showed organic nitrogen and total
nitrogen in the stream at the refuse dump essentially to double during a heavy frost
rainstorm. Although the data are not conclusive they would seem to justify a policy
of excluding refuse fills from the Tahoe Basin.
The results reported for marinas and keys (Table 3-3) are particularly
deceptive. Although they show an increasing response to increasing concentration
of mixtures of such waters with water from the open lake,, the maximum value of ja^
is no greater than that reported for LTW in Table 3-1. The most important reason
for this was reported [3] in relation to pilot pond assays and in observation of
confined water at North Tahoe. This is that even in a highly eutrophied water in
which the most casual observer may see a rich growth of plants, an assay of filtered
water reveals only the residual ability of the water to stimulate growth. When
nutrients are tied up in living cells no assay of the water in which they live can
reveal the level of nutrient which produced the existing biomass.
Of the creek waters reported in Table 3-3, Meeks Creek and Ward Creek were
essentially the same as LTW alone in the matter of growth response. Both in magni-
tude of growth rate and indifference to concentration this fact was evident. At
the time of the survey both of these creeks were experiencing little intensive land
development on their watersheds. Development on the Incline Creek watershed was in
an early stage and although the water appeared of high quality, mean values of ji^
showed a definite increase in response as concentration increased. If the results
were strictly interpreted on the assumption that all values are statistically highly
valid, one might see at the 1$ concentration evidence of toxicity. However; this is
not borne out by the results of greater concentration. Therefore it must be assumed
that within the limited number (k) of samples assayed and within the range of accuracy
of analysis lies the variation, and that Incline Creek was little different than Lake
Tahoe at the time of the survey (a condition which did not persist subsequently; see
Chapter V).
In contrast with the other creeks assayed, the Upper Truekee-Trout Creek
system showed a definite increase in stimulatory effect with concentration in LTW.
This might be expected because the drainage area of this system of surface streams
represents a land area on which development is well established.
Conclusions
The assays reported in Table 3-3 were, of course, of the nature of a survey
to determine which possible sources of influent nutrient to Lake Tahoe might be
worthy of further study by pond assays on a pilot scale. The conclusions from the
flask assay survey were that:
1. Sewage effluents were the most important source of nutrients which
might trigger eutrophication of surface waters such as Lake Tahoe.
2. Septic tank leaching field effluents were not particularly different
than other sewage effluents but are too difficult to collect in
adequate quantities for pond assays of the scale planned (see
Chapter IV).
3. The source of nutrients in the Upper Truckee-Trout Creek system
should be explored, but pond assays were impractical because of
the long distance (approximately 25 miles) between the creeks and
the pilot pond installation.
32
-------
^. Other creeks surveyed could not effectively be assayed by pond assay
unless 100 percent concentration of the creek water could be used.
This was infeasible because the water quantities needed for continuous
flow studies could not be delivered to the ponds, which, as shown in
Chapter IV, are not a portable installation.
5. The influence of land development evident in the comparison between
Upper Truckee -Trout Creek and other creeks surveyed should be
monitored through a program of long term flask assays of the creek
waters and evaluated in terms of a similar continuing monitoring
of Lake Tahoe water. (See Chapters V and VI for results.)
CHEMOSTAT ASSAYS
Pursuant to the objective of applying the most effective method available to
the determination of the algal growth stimulating potential of various possible
sources of enrichment of surface waters, assays with laboratory scale chemostats
were undertaken simultaneously with flask assays. Using continuous flow equipment
such as illustrated in Figure 2-1 and the theoretical considerations set forth in
Chapter II, fifty experiments were conducted to determine the growth response of
S_. gracile in four types of samples:
1. Surface runoff
2. Sewage effluents
3. Waste water seepage
k. Added chemical nutrients (nitrogen and phosphorus).
Because of the difference in the period of time required for the flask and
chemostat assays, it was impossible to run parallel tests on the same sample
simultaneously. However ; when duplicate growth assays of the same sample were
conducted, excellent agreement in results were obtained although the numerical
values of ja, were dissimilar because of the different growth conditions prevailing
in the two systems. (See Chapter II, "Limitations of Bioassay Techniques.")
It was soon evident from the studies that a great deal more research and
development of technique was necessary in order to make the laboratory chemostat
a reliable method of bioassay despite its theoretical advantages over the flask
method. It was particularly evident that a poor place to begin such needed develop-
ment was in a situation such as at Lake Tahoe where the nutrient concentrations in
the lake water were near the bottom limit of resolving power of analytical chemical
methods; and where the objective was to determine at what threshold algal growth
stimulation was detectable. Great difficulty was experienced in maintaining steady
state conditions at statistically valid levels with the small number of cells
supportable by low nutrient concentrations.
Assuming that the maximum growth rate in a chemostat during the transient
period before a steady state is reached (pL ) is analagous to the maximum growth
rate (uO in flask assays, 25 pairs of data were compared. The results indicated
a relationship roughly as follows:
Thus it might be postulated that neither the flask assay nor the chemostat assay in
its transient state represent the maximum growth rates that could be maintained in
a near steady-state continuous culture. This would mean that the flask assay growth
rate is less sensitive than might result from a system which maintains a culture in
the log phase of cell growth. As noted in Chapter II, this might lead to failure of
the assay to identify the exact nutrient concentration where growth stimulation of
-------
the test alga begins, but it does not negate the conclusion that if cells multiply
in a flask culture the nutrient source had best be excluded from Lake Tahoe in the
interests of prevention of eutrophication. It may well be that such an insensitivity
is more theoretical than real because as shown in Table 3-3 with tertiary effluents,
a profound affect appears at low concentrations (1$) and increases with concentration,
Presumably this situation would continue as it does in algal growth units until the
density of the culture becomes controlled by light penetration and environmental
conditions other than nutrients. Also, in any event, the relationship between the
response of a test alga and the response of a complex ecosystem outdoors is at best
obscure.
Kinetic constants £, Y, KS, and k^ (see Equations 1 and 2, Chapter II) were
computed from a series of chemostat assays reported and analyzed statistically in a
previous publication [1], Although they led to some interesting preliminary findings
they did not satisfactorily substantiate the applicability of the Michaelis-Menten
model and left unanswered whether crudity of data or limitations of the model were
at fault. They did, however lead to two important conclusions:
1. That the laboratory chemostat was not sufficiently perfected for the
purposes of the study at the time it began, hence the flask assay
method was the "best available method" for the study.
2. That work should be undertaken to establish a standard assay pro-
cedure for assessing the algal growth stimulating potential of
nutrients which might be discharged to any surface water, or
which already exists therein.
Because work on such an assay procedure was begun early in 1908 by the
Federal Water Quality Administration, with full access to the Tahoe findings, and
because the work of the FWQA on its Provisional Algal Assay Procedures (PAAP) test
has advanced far beyond that reported by the authors [1] in 1968, the details
previously reported are not repeated in this summary.
-------
CHAPTER IV
POND ASSAYS OF WASTE WATER EFFLUENTS
INTRODUCTION
During the summer and fall seasons of both 1968 and 1969 outdoor pond assays
were made to assess the algal growth response of Lake Tahoe water to various concen-
trations of effluent from 'Secondary and tertiary sewage treatment processes. The
ponds were designed to simulate the shallow portions of the lake where summer water
temperatures are most favorable for algal growth, circulation is most likely to be
impeded, and increased growth of algae would be most noticeable to people and hence
most aesthetically objectionable in the initial stages of accelerated eutrophication
of the lake.
The ponds were conceived and operated as continuous flow systems at a steady
state where growth is balanced by the outflow of organisms. Since only two
variables residence time (0) and input concentration (SQ) can be controlled,
this assumption implies that one factor limits the growth of living material;
possibly nitrogen, on the basis of previous flask assay surveys (Chapter II).
However, under outdoor conditions there are many variables which might affect the
growth rates of organisms. Sunlight, temperature, foreign (allochthonous) material,
seasonal variation in chemical composition of lake water and sewage effluents,
residence time, and the complexity of aquatic ecosystems are all known to be
determinants of productivity in nature. The possible effects of such determinants
on the feasibility of attaining steady state conditions was beyond control in the
pond assays. Similarly, residence times were necessarily related to attainable
steady state conditions in the ponds rather than to the periods of confinement of
water that might occur in natural embayments or man-made marinas and keys. Thus
pond assays might yield results more favorable or less favorable than those
prevailing in the lake. Nevertheless it was assumed from the beginning that if
pond assays should show growth stimulation by the effluent concentrations assayed,
such effluents could be expected to accelerate the natural rate of eutrophication
of oligotrophic waters such as Lake Tahoe even though the values; of observed growth
rates (jj) might be numerically inexact.
NATURE AND OPERATION OF POND ASSAYS
Physical Nature of the Pond System
The system used in pond assays consisted of eight fiberglass-coated wooden
tanks each 20 ft long, k ft wide, and h ft deep, with a water depth of approximately
3.5 ft and a capacity of about 7930-jf (2100 gal). As shown schematically in
Figure ^-1, the ponds were installed on a wooden platform adjacent to the south
wall of the Fish and Game hatchery building, which housed the laboratory, with the
long axis on the meridian. At the north end of each pond a weather-tight, ventilated
cabinet was constructed to house the nutrient sample containers, feed pumps,
electrical controls and outlet boxes. A Jaccuzi Whirlpool submersible pump was
installed in each pond and operated continuously during assay experiments to keep
the pond moderately well mixed. The volume of water in the pond was maintained
constant by a 1-1/2 in., galvanized iron riser standpipe threaded into an upside
down floor flange built into the pond bottom near the south end of the structure.
This standpipe could be removed for draining and cleaning of the pond between
experiments, or assays.
Lake Tahoe Water (LTW) used in the pond assays was pumped directly from the
lake by means of a centrifugal pump located near the shoreline. The pump intake
35
-------
1
FISH AND GAME
HATCHERY BLDG.
LTAC
LAB.
1
2
P
3
O
4
N
5
D
6
S
7
LAKE
TAHOE
HOUSE
FIGURE 4-1 LAYOUT OF EXPERIMENTAL PONDS
-------
was placed approximately 100 yd offshore in about 10 ft of water at k ft above lake
bottom. The pump discharged through 2000 ft of 2-in. PVC pipe into a horizontal
6-in. PVC header supported on a superstructure of cabinets at an elevation of
approximately 3 ft above the pond water surface and extending across the entire
8-pond installation. Flow into each pond was by gravity through a small plastic
line originating in the common header and fitted with a valve, by which the rate
was controlled to provide the desired detention period, or residence time. Excess
water delivered to the header was discharged over the riser standpipe and returned
to the lake via a natural drainage channel.
Operation of Pond Assays
Before beginning each assay the ponds were washed, rinsed, and filled with
LTW. The residence time was adjusted before the assay began by regulating the
quantity of LTW entering the ponds by way of the pond header pipe. The sample
containing the enriching nutrient to be evaluated by assay was then pumped into
the pond from a 5-gal plastic container by a Sigmamotor pump at a uniform rate
appropriate to produce and maintain the desired concentration of sample in the LTW
at the selected residence time, hence nutrient levels and growth of algae should
approach to steady state simultaneously. Two reference ponds containing only LTW
were maintained at the same residence time as the experimental ponds. In the
initial pond assays an attempt was made to utilize S_._ gracile as a test alga as in
flask assays. Stock cultures of £>_._ gracile were grown in large quantity and
introduced into both the reference and the assay ponds. However, indigenous
organisms, primarily diatoms, overwhelmed the test alga in all ponds. Consequently
cell counts of S. gracile were useless as a measure of growth response. Attempts
to remove indigenous organisms from incoming lake water by a diatomaceous earth
swimming pool filter resulted in hydraulic losses that could not be overcome except
at an unacceptable sacrifice of time while new pumping equipment was being obtained.
Therefore, in all subsequent pond assays indigenous organisms contained in LTW
comprised the inoculum of each pond.
The experimental design used in pond assays during the 1968 and 1969 seasons
are summarized in Table ^-1. The ponds were operated on a 10-, 5-> and 3-day
detention time in the first series (1968). In 1969 the maximum detention time was
reduced to 8-days as experience showed this to be adequate for the assay: at the
various detention periods both secondary and tertiary effluent from the STPUD Water
Reclamation Plant were used as the major nutrient source. Secondary effluent was
obtained as grab samples from the clarifier effluent following activated sludge
treatment. Tertiary effluent was obtained as grab samples from the effluent from
the activated carbon filter units (before chlorination). Essentially, tertiary
treatment consisted of precipitation with lime to remove phosphates, volatilization
of ammonia gas in an ammonia stripping tower, pressure filtration, and activated
carbon filtration. The effluent was collected and transported to the pond site as
needed in approximately 100 to 200 gal lots, in 5-gal polyethylene bottles and
generally used within one week after collection.
Measurement of Growth Response
As reported in Chapter III, maximum cell counts (X) and maximum growth
rate (ja) were used as indicators of growth response of S_._ gracile in flask assays.
Moreover, the reasonably uniform size and specific gravity of cells made possible
an estimate of biomass produced by the unialgal culture. In the pond assays,
however, cell counting was infeasible because of cell diversity and allochthonous
material in the system. Several techniques for estimating biomass were studied
[2] and volatile suspended solids (VSS) was chosen for the pond assays because it
showed the highest order of correlation with other factors determined, in addition
to being easy to measure by well established and simple laboratory procedures.
The biomass produced in pond assays was primarily pennate diatoms which grow
attached to the submerged surface of the pond structure. Consequently in order to
sample the biomass in a pond the submerged surface was first scraped thoroughly
37
-------
TABLE k-I
EXPERIMENTAL DESIGN OF POND ASSAYS
Assay
No.
-3
2d
^)
k
5d
6d
7
1
2
3
k
5
6
Residence
Time
days
(0)
10
5
3
3
10
5
8
5
3
8
5
3
Dates
(1968)
14 Jun -2 Jul
5-29 Jul
2-l6 Aug
16-30 Aug
1 Sept -k Oct
k Oct -1 Wov
(1969)
Ik Jul -8 Aug
9-22 Aug
23 Aug-3 Sept
8 Sept-30 Oct
4-17 Oct
18-31 Oct
Pond Numbers
1
LTa
LT
Seed Pond
Seed Pond
1.0$ II
LT
LT
LT
LT
LT
LT
LT
2
"h
0.1$ III
0.1$ II
0.1$ III
0.1$ II
0.1$ III
0.1$ III
0.1$ II
0.1$ II
0.1$ II
2.0$ III
2.0$ III
2.0$ III
3
1.0$ III
1.0$ II
1.0$ III
1.0$ II
1.0$ III
1.0$ III
1.0$ II
1.0$ II
1.0$ II
1.0$ III
1.0$ III
1.0$ III
k
1.0$' III
1.0$ II
1.0$ III
1.0$ II
1.0$ III
1.0$ III
1.0$ s-ne
1.0$ s-ne
1.0$ S-II6
1.0$ III+TEf
1.0$ III+TEf
1.0$ III+TEf
5
LT
LT
LT
LT
LT
LT
LT
LT
LT
LT
LT
LT
6
0.1$ IIG
0.1$ III
0.1$ II
0.1$ III
0.1$ II
0.1$ II
0.1$ II
0.1$ II
0.1$- II
2.0$ III
2.0$ III
2.0$ III
7
1.0$ II
1.0$ III
1.0$ II
1.0$ III
1.0$ II
1.0$ II
1.0$ II
1.0$ II
1.0$ II
1.0$ III
1.0$ III
1.0$ III
8
-
1.0$ II
1.0$ III
1.0$ II
1.0$ III
1.0$ II
1.0$ II
1.0$ s-ne
1.0$ s-iie
1.0$ s-ne
1.0$ III+TEf
1.0$ III+TEf
1.0$ III+TEf
CO
CO
a
Shore Lake Tahoe water.
13 II is Secondary Effluent from the South Tahoe Public Utility District (STPUD) Water Reclamation Plant.
CIII is Tertiary Effluent from STPUD.
Trends were seeded initially with Selena strum gracile.
SS-II is simulated secondary effluent prepared by adding macronutrients^ iron, and trace elements in excess plus KHg
P04-P equivalent to the concentration measured in the secondary effluent (see Table C-6, Appendix C) .
_p
III+TE is tertiary effluent with quantities of iron and essential trace elements added (see Table C-6, Appendix C).
and
-------
with a rubber squeegee and the dislodged material dispersed throughout the pond water
by circulating it for approximately one-half hour before samples were withdrawn for
VSS analysis.
Physical and Chemical.Analyses
Physical and chemical analyses of the pond water were made at regular
intervals during each assay. Grab samples for such analyses were collected just
below the water surface at the midpoint of the pond at ,the time of sampling for
VSS. Routine chemical analyses were performed on both filtered and unfiltered pond
samples. Analyses of the unfiltered samples were: SS, VSS, organic-N, NH3-N, and
total phosphorus. The filtered pond samples were analyzed for: organic-W, MH3-N,
N02-N, N03-N, total-N, P04-P, total-P, Fe, conductivity, and pH. Chemical analysis
of the nutrient source to the pond included, in addition to the above, COD and BOD
of the unfiltered samples; and calcium, chloride, and alkalinity in the filtered
samples. Bioassays by means of flask cultures were also performed routinely when
the pond was considered to be operating under steady state. Results of analyses
made during the 1968 assays (Table 4-1) are presented in detail in Table C-l and
Table C-2, Appendix C. The somewhat more comprehensive analyses made during the
1969 pond assays (Table 4-1) likewise appear in Appendix C as Tables C-J and C-4.
Environmental Data
Records were kept of some of the environmental conditions prevailing during
the periods when pond assays were in progress. Solar radiation, sky conditions,
precipitation, daily temperature-range, barometric-pressure, wind direction and
velocity, and pond water temperature were among the data obtained from a variety
of sources or by direct observation. Only such details of these as are pertinent
to an interpretation of the pond assay results are presented in this chapter.
Detailed tables appear in previous annual reports [2,3] of the project.
Analysis of Data
The computer was utilized to analyze data, especially to obtain values of
maximum growth rates, j}; log maximum growth rate, j}^; mean value of maximum cell
growth at end of period, X; nutrient coefficient, KS; yield coefficient, Y; and
the decay rate k^. The computer was also utilized to determine statistical
parameters and correlation factors used in evaluating the results' of assays.
RESULTS OF POKD ASSAYS
Environmental Factors
Figure 4-2 shows graphically the variation in three important environmental
factors during the pond assays of 1968 and 1969:. solar radiation, mean water
temperature, and mid-range air temperature. The mid-range air temperature is the
calculated average of daily high and low values observed at the U. S. Coast Guard
Station less than one-quarter of a mile from the pond installation. Obviously it
is not necessarily the mean air temperature over 2k hours, but in the absence of a
continuous temperature record it is taken as a fair approximation of such a mean
for the purposes of this study. Table 4-2, computed from more extensive data [J>]
for 1969 shows that during the period of pond assays in that year (July 10 - October
3l) the variation in pond water temperature was only about 20 percent of that of
the air.
39
-------
- 400
Solor Rodiallon
Pond Temperature
Air Temperature
- TOO
- 600
- 500 <
£
i1
- 300
<
Q
2
cc
<
- 200
May 15, 5/30 6/W 6/29 T/W 7/29 8/13 8/28 9/12 9/27 K3/I2 KV27 Novll,
1968 || || I I I 11 I I 1968
[»Assoyl~| |»Assay 2~j [-Assay
ssoy 6 -
Assay 7)
LU
CC
O
fe
cr
ui
o_
5
LU
700
- 650
Mean Pond Temperature
Mid - Range Air Temperature
Solar Radiation
Sept I
| Assay 2 ->j |~ Assay 3 |
250
Oct I Oct 31,1969
Assay 4 ^ [Assay 5 >J j Assay 6 -j
FIGURE 4-2. VARIATION IN ENVIRONMENTAL FACTORS DURING POND ASSAYS
-------
TABLE h-2
DAY-TO-NIGHT VARIATION IN AIR AND WATER TEMPERATURES (1969)
Month
(1969)
Jul
Aug
Sep
Oct
Jul 10-Oct 31
Air
Range of
Temperature
Variation
(°F)
19 k2
-^ ^
18 k6
6 - 39
6 - ^7
Average
Temperature
Variation
(°F)
35
hi
35
25
3^ (-)
Pond Water
Range of
Temperature
Variation
(°F)
6 - 9
5 - 9
3 - 8
1 9
1 9
Average
Temperature
Variation
(°F)
7
7
6 (-)
^.7
6.6
From Figure U-2 it is evident that the mean water temperature tended to
follow the mid-range air temperature. However, the changes were less abrupt. Two
factors combine to bring about this slower response. The first is the limited
thermal capacity of air as compared to water. The second is that the temperature
of Lake Tahoe water at the pump intake depth (approximately 7 f"t below the water
surface) tends to be somewhat constant from day to night. Consequently, variation
in pond water temperature is a function of air-water temperature relationships at
the ponds only; and the effect is least evident as the hydraulic residence time Is
decreased.
From Figure h-2 it may be seen that the mean daily pond water temperature
was fairly uniform during the period when Assays 1 through 3 were in progress,
whereas it steadily decreased during the fall season when Assays k through 7 were
made. In contrast with the curves of air and water temperature, the curve of solar
radiation shows essentially a constant downward trend from mid-July through October.
During September and October the trends of air and pond water temperature curves
generally parallel the trend of solar radiation, although during the warmer summer
months when back-radiation from the earth at night is greatest, both air and water
temperatures showed the expected lower rate of decrease with time than did solar
radiation.
Decreasing pond water temperatures as well as reduced solar radiation input
directly affects aquatic growth. For example, a "rule of thumb" for bacterial
systems is that the "growth rate doubles for each 10°C increase in temperature."
Presumably the reverse is also a valid assumption. It is noteworthy that during
Assays 5 and 6 in the 1969 series the pond water temperature was at or below the
level (10°C) at which biological activity becomes seriously reduced. Therefore
although Figure k-2 in itself shows nothing unusual from a climatological viewpoint,
it does show changes during some assays which may be useful in interpreting the
results of such assays in terms of growth stimulation in relation to available
nutrients.
Biomass Measurements
The growth response of indigenous organisms in Lake Tahoe in terms of VSS
pertaining at steady state in pond assays of sewage effluents are presented in
detail in Tables C-3 and C-5 of Appendix C. Paired ponds were used in all assays;
although in different assays of any individual effluent the position of the pairs
in the l-to-8 sequence (Figure k-l) was changed in order to randomize any effect
-------
of the geometry of the system. However,, because LTW served as the control, ponds
No. 1 and No. 5 (Figure 4-1) were constantly used to assay the raw lake water.
Theoretically, the biomass levels at steady state should be the same in duplicate
ponds.
Results of the pond assays are shown in Table U-3. For purposes of identi-
fication the letters E (east) and W (west) are used in the table to denote the
relative positions of paired ponds. Pond numbers from Figure U-l are also included
in the table. An analysis of variance for paired ponds was made. Underscored
values in the table show that in 6 of the 31 assays the biomass level in paired
ponds was significantly different at the 95 percent confidence level.
From Table 4-3 it is evident that the growth stimulating response of organ-
isms increased with concentration of sewage effluent added. Biomass produced by
O.l/o secondary effluent was about the same as that produced by 1.0$ tertiary effluent.
Contrary to what might be expected from the low temperatures shown in Figure k-2,
there was no evidence that growth response was reduced in either LTW or other samples
by the cold weather prevailing during assays No. 5 and No. 6 in 1969.
Some variation in the response of LTW is evident but the pattern is not clear.
In Chapter V this is shown to be a seasonal phenomenon in terms of nutrients. Figure
4-3 shows the variation in suspended solids (SS) and volatile suspended solids (VSS)
delivered to the pond headers from the near-shore pumping station intake during the
July-October 1969 assay period. Similar but not comparable data were reported [2]
for the 1968 assay period but related to the ponds rather than the influent because
it had not at the time been established that VSS was the biomass measure finally
to be used.
From Figure 4-3 it is evident that on occasion the SS concentration fluctuated
more than that of the VSS, indicating a more than normal input of inorganic solids.
A careful analysis of this phenomenon [3] showed wind disturbance of the shallow
portion of the north end of the lake to result in pickup of sediments, both inorganic
and organic, particularly during assay No. 5- From Table 4-3 it is evident that
any effect on the biomass produced was damped out by the 5~clay residence period in
the pond, or was less significant than other factors which lead to variation in
biological systems response.
Inventory of Quality Parameters in Pond Assays
Elaborate statistical studies were made [2] in an attempt to relate biomass
production to nutrient concentration. However, an inventory and rough materials
balance proved to be one suitable way to account for the major constituents of the
pond water involved in changes in biomass. For this purpose calculations were made
from the initial (Table C-4, Appendix C) and final (Table C-3, Appendix C) concen-
trations of several water quality parameters or constituents. Suspended (SS) and
volatile (VSS) suspended solids; organic-N, NH3-N, (N02 + N03)-N, total inorganic-N,
and total N; P04 and total-P; and conductivity were the parameters inventoried. The
results of the most pertinent of these inventories are presented hereinafter in a
series of tables which summarize only the final relationship of input to output of a
particular quality factor. A positive (+) sign is used in the table to indicate an
input in excess of output of material in its original (input) form. Conversely, a
negative (-) sign indicates that more material appeared in the effluent than entered
the system as a given compound or factor.
The tables do not represent a strict mass balance of material because of
several generally unavoidable assumptions, including:
1. No material entered the ponds except by way of Lake Tahoe water and
the added nutrient feed.
2. Evaporation and precipitation were negligible.
3. Constituent concentrations in the ponds were equal to concentrations
in the outflow.
42
-------
TABLE 4-3
COMPARISON OF BIQKASS ESTIMATES BETWEEN PONDS KECEIYIKG THE SAME EFFLUENT
Assay
No.
(1968)
2
3
1)
5
6
7
(1969)
1
2
3
4
5
6
Keen Eiooess Valuea, c£ ^ VSS
LTW
E
(5)
0.93
(5)
0.33
(5)
0.48
(5)
0.91
~w
0.77
(5)
0.66
(5)
0.84
(5)
0.86
(5)
0.87
w
(1)
0.88
(1)
0.39
(1)
0.58
(1)
0.79
(1)
0.71
(1)
0.58
(1)
0.57
(1)
0.84
(1)
0.74
C.1% II
E
(6)
1-39
(6)
1.29
(6)
0.91
w
(2)
1.29
(2)
1.09
(2)
1.56
1.0% II
E
(8)
2.17^
W
2.23
(8)
2.09
00
2.45
(6)
2.36
(8)
5.10
(7)
5-17
(7)
6.30
(7)
4.65
w
(7)
M7!
(3)
3.09
(7)
2.32
(3)
3.00
(7)
2.65
(7)
4.10
(3)
5-12
(3)
6.72
(3)
5-62
1.0% S-II
E
(8)
4.88
(8)
5.66
(8)
3.23
w
00
5-31
00
6.5C
(-;
L ' X
;.o% in
E
(6)
1.14
(6)
1.48
(6)
3.7S
w
(2)
1.10
(2)
2.17
(2)
4.81
1.0% III
E
00
1-59
(8)
1.24
0*)
0.89
(8)
1.34
0*)
0.92
(4)
0.68
(7)
1.14
(7)
1.42
(7)
1.74
W
(3)
1.77
(7)
1.72
(3)
0.76
(7)
1.47
(3)
1.04
(3)
0.76
(3)
0.63
(3)
0.95
(3)
1.90
1.0% III+TE
E
(8)
1.24
(8)
1.46
(8)
1.84
W
CO
1.16
W
1.64
00
1.75
KOTE: Values In parentheses in columns headed "E" and "V" iJiiUate pond numbers from Figure 4-1.
aLTW Lake Tahoe vs"er; II secondary effluent; III tertiary effluent; S-II is simulated secondary
effluent prepared by adding .tacror.utrlents, iron, end trace ele-er.ts in excess plus NH3-N and P04 -P
equivalent ^o the corjcer.tret ion nessured Lr. the secondary efflM=-t (see Table C-6, Appendix C); III+TE is
tertiary effluent with quantities of iron and essential trace eU^ents added (see Table C-6, Appendix C).
Underscored values indicate that replicate ponds vere significantly different at P > 0.95-
-------
-p-
4=-
o
<
LU
o
2
O
o
CO
CO
3.5
3.0
2.5
2.0
1.5
1.0
0.5
o- o Volatile Suspended Solids
Suspended Solids
Afternoon Wind Velocity
I
E
July 14,1969 Aug 1
Septl
Oct 1
Oct 31,1969
Assay 1
p Assay 2 -»] p-Assay 3 H
Assay 4 - <] p- Assay 5 >j p Assay
FIGURE 4-3. VARIATION IN SOLIDS CONCENTRATION IN NEAR-SHORE
LAKE TAHOE WATER DURING POND ASSAYS (WIND VELOCITY
ADDED)
-------
Such assumptions are of varying degrees of validity. The first is perhaps
the most visionary. Allochthonous material transported by the wind did indeed
get into the ponds in varying amounts and at no predictable or constant rate.
Moreover, some of it settled, some stayed in suspension, some was presumably
soluble, and some floated on the surface.
Except for one period in October near the end of Assay No. 5 there was no
precipitation of consequence. However on that one occasion about 1.7 in. of rain
fell in two days. What it brought into the ponds in terms of participate matter
and nutrients is not readily estimated. As for evaporation, values of 0.1 to
0.2 in. per day are possible in the area but vary with the season. Measurement
was beyond the scope of the study, hence no evaporation data were available.
Assumption number 3 is reasonably valid in the case of dissolved material,
because of constant mixing of the tank contents by whirlpool pumps. It is of less
validity in the case of attached solids or settleable solids too large to be
significantly disturbed at the mixing rate which prevailed, because the indigenous
lake algae responsible for biomass increase and utilization of nutrients are mostly
attached forms of diatoms. As noted previously the sides and bottom of the tank
were squeezed and the tank contents thoroughly mixed before each sampling for biomass
(VSS, mg/V) determination. This minimized the error in growth rate calculations;
and maximized it for solids inventory because it led to the assumption that the
observed solids concentration pertained throughout the period between samplings.
In reality, the solids thus obtained represented those constantly present in the
pond effluent, plus those that had accumulated since the last squeegeeing and
mixing routine. The Imprecision inherent in assumption 3 is not a result of
faulty experimental design. Rather it is the penalty which must be paid when
outdoor pilot experiments simulate natural conditions, with all the uncontrollable
variables associated with such conditions.
SS and VSS
Tables 4-4 and 4-5 summarize the results of inventories of suspended and
volatile solids for all ponds and all pond assays. Subject to the limitations
discussed in the preceding paragraph, they account for algal growth which took
place in the ponds during the six assay experiments. An inspection of these tables
shows that most values are negative. This is consistent with the concept, and
the observed fact, that algal cells increased during the assay at the expense of
dissolved nutrients.
TABLE 4-4
IWVEMTORY OF SUSPENDED SOLIDS IN PONS ASSAYS
(all values in grams)
Pond
No.
^ LTW
2 Sewage
6 Effluents
3 Sewage
7 Effluents
4 Chemical
8 Nutrients8
Assay Number (See Table 4-1)
1
- 19
- 17
- 53
26
113
- 119
- 90
- 123
2
- 26
- 27
- 55
- 4l
- 211
235
- 263
- 269
3
32
- I|-7
- 5^1-
- 186
228
168
286
4
- 14
- 5
- 17
+ 17
- 19
3
- 18
3
5
+ 19
+ 9
+ 9
- 3
- 4
+ 20
- 5
- 13
6
- 28
- 265
- 270
- 137
- 78
- ill
- 93
aAssay 1 to 3 was simulated secondary effluent; Assay 4 to 6 was
tertiary effluent plus trace elements.
-------
TABLE 4-5
INVENTORY OF VOLATILE SUSPENDED SOLIDS IN POND ASSAYS
(all values in grams)
Pond
No.
1
5
2
6
3
7
4
8
Assay Number (See Ta'ble 4-l)
1
- 9
10
- 18
- 14
- 65
- 67
- 52
- 63
2
8
7
18
13
95
107
109
113
3
9
9
13
30
109
151
79
111
4
- 1
- i
- 6
+ lk
8
2
13
5
5
1
1
13
18
18
3
13
20
6
11
11
82
105
42
25
34
34
An evaluation of Ta'ble 4-4 and 4-5 in the light of Table 4-1
reveals that the negative values, indicative of cell growth, tend to increase as
the added nutrient concentration increases. For example, Pond No. 1 and 5,
containing unfortified LTW show the lowest increase; and Ponds No. 3 arid 7,
containing 1$ secondary effluent show the greatest. The tables also show in most
instances a reasonable degree of compatability between the two ponds constituting
an assay of any particular material. The widest deviations from this general
case appears in Table 4-4, Assay No. 5, when input exceeded output. As discussed
in relation to Figure 4-3, Assay No. 5 was in progress in October when wind and
weather conditions brought in a very large amount of suspended solids which were
not volatile. It is notable that volatile solids in Assay No. 5 (Table 4.5) failed
to show the positive values or wild fluctuation evident in suspended solids.
Nitrogen Compounds
Tables 4-6, 4-7, and 4-9 summarize the change in various nitrogen
compounds during each of the several pond assays. In each case where nutrients
were added (i.e., Ponds 2,6; 3,7; and 4,8) essentially all of the values are
positive, indicating by the convention adopted (see page 30) that more nitrogen
went into the assay in the forms indicated in the table headings than came out of
the ponds in that same form. In the case of the Lake Tahoe water (LTW) control
ponds (i.e., Pond 1,5, all assays) the consistency between duplicate ponds was
not as great for nitrogen as for volatile solids or suspended solids. The greatest
disagreement between Ponds 1 and 5 seems to have occurred with ammonia. Only Assay
No. 5 showed a consistent loss of ammonia. In other assays gains and losses appear
q.uite random. This inconsistency is a result of both the small amount of ammonia
present, the limitations of assumption, the precision of measurement possible at
low concentrations, and unobserved biochemical changes which probably occurred in
the pond biomass. The more conservative forms of nitrogen, (N02 + N03), although
in low concentration, showed a somewhat more consistent check in LTW ponds.
Inorganic and total nitrogen showed more gains than losses in Assays 4, 5, and 6.
Relative to assays of LTW with added nutrients, the most consistent pattern
is evident in Ponds 4 and 8 to which chemicals in the form of K2HP04, NH4C1,, iron,
46
-------
TABLE 4-6
INVENTORY OF SOLUBLE AMMONIA-N IN POND ASSAYS
(values in
Pond
No.
1
5
2
6
3
7
4
8
Assay Number (See Tat>le 4-l)
1
- 44
623
600
874
3903
^585
2072
2143
2
65
43
609
214
^5
4549
3814
3735
3
- 87
6
872
184
5376
5662
4865
4886
4
- 277
- 687
1238
225
427
1044
827
461
5
296
262
1858
734
806
630
1400
945
6
- 354
- 521
5180
4015
1949
1501
1800
1914
TABLE 4_7
INVENTORY OF SOLUBLE (N02 + N03)-N IN POND ASSAYS
(values in mg)
Pond
Wo.
1
5
2
6
3
7
4
8
Assay Number (See Table 4-1)
1
87
88
220
209
834
880
123
138
2
46
63
76
68
356
334
52
51
3
21
24
80
172
832
838
127
153
4
3
- 6
- 381
- 80
50
53
- 55
- 24
5
187
121
14
97
20
18
96
132
6
127
153
118
52
80
73
- 239
- 151
-------
TABLE U-8
INVENTORY OF SOLUBLE TOTAL INORGANIC-N IN POND ASSAYS
(values in mg)
Pond
No.
1
5
2
6
3
7
4
8
Assay Number (See Tatle ^-l)
1
1A
712
820
1083
4737
5^65
2195
2281
2
111
21
68k
282
5300
W83
3866
3785
3
- 108
29
952
356
6209
6^99
1+992
5037
k
273
693
858
1^5
478
1097
772
106
5
W3
383
18H
831
826
6^-8
130^
812
6
227
367
5298
ko66
1868
1575
1562
1762
TABLE 1|_9
INVENTORY OF SOLUBLE TOTAL-N IN POND ASSAYS
(values in mg)
Pond
No.
1
5
2
6
3
7
4-
8
Assay Number (See Talole 4--1)
L
4-51
633
4-99
1202
4-875
4-696
1609
604-
2
179
230
106
604-
5228
4584-
2994-
2295
3
66
1184-
- 24-80
- 14-79
2390
3676
1398
2983
4-
- 795
- 687
703
1011
57^
1250
798
27
5
- 2898
39
204-4-
UA8
4-04-
381
595
1161
6
135
2397
234-4
3702
801
325
1982
2270
1*8
-------
and trace elements were added to LTW in Assays 1, 2, and 3 to provide P and N at
approximately the same levels observed in the effluent fed to Ponds 3 and 7.
From the inventory of nitrogen compounds it may be concluded that with
limited exceptions a decrease in all forms of nitrogen occurred, indicating that
biomass was increasing, as previously shown "by an increase in volatile solids
(Tablet-5 ).
Phosphorus
Changes in the amount of phosphorus entering and leaving the ponds, as
measured by analyses for P04-P and total P, are summarized in Tables 1+-10 and 4-11.
Phosphorus concentration being extremely low in Lake Tahoe water, the inconsistent
inventory data shown in the tables for Ponds 1, 5 are not surprising. P04-P values
are consistent between replicate ponds in essentially all cases during Assays 1,
2, and 3, in which secondary effluent was the added source of nutrients (except
Ponds k and 8; chemically fortified LTW). Assays k, 5, and 6, involving various
dilutions of tertiary effluent show a much smaller loss of phosphorus than Assays
1, 2, and 3j and (Table 4-5) a correspondingly low increase in volatile solids.
Because phosphorus removal was a major aspect of tertiary treatment the results
may mean that this element (P) was the growth limiting factor in Assays 4, 5j and 6,
TABLE k-W
INVENTORY OF SOLUBLE P04-P IN POND ASSAYS
(values in mg)
Pond
No.
1
5
2
6
3
7
4
8
Assay Number (See 'Table 4-l)
1
10
4
157
122
1974
1898
2209
2304
2
21
3
113
1^3
l4l6
1474
1738
1801
5
3
3
167
188
1854
2057
1955
2103
k
9
18
55
kk
50
37
6k
52
5
10
17
68
60
8
41
32
ki
6
2k
3
128
105
^
62
32
14
-------
TABLE 4-11
INVENTORY OF SOLUBLE TOTAL P IN POND ASSAYS
(values in mg)
Pond
No.
1
5
2
6
3
7
4
8
Assay Number (See Table 4-l)
1
30
26
- 93
90
1656
1527
1909
1889
2
- 672
- 236
- 80
- 265
981
1142
l4lo
1536
3
98
- 56
77
- 264
1865
- 2121
1970
2108
4
33
34
11
82
74
- 48
130
73
5
97
119
172
221
247
217
272
101
6
74
26
163
187
138
107
85
46
Growth Limiting Nutrient
To evaluate the presumptive evidence that phosphorus was growth limiting
in Assays 4, 5, and 6 the nitrogen/phosphorus ratio was computed for two cases
NH3-N vs P04-P; and total inorganic N vs P04-P. The results are presented in
Table 4-12 . Because the purpose of the computation was to identify the growth
limiting factor rather than to separate the stimulatory effect of LTW and added
nutrients the data in the table reflect the actual situation in the pond within the
limits of error and assumption. LTW (Ponds 1 and 5) is omitted from the table
because at the low concentration of nutrients in LTW negative values are experimentally
unavoidable (see Tables 4-5 and 4-ll).
In interpreting the data in Table 4-12 use may be made of the general rule
that an N/P ratio less than 10 identifies a nitrogen limiting situation,, whereas
a N/P ratio of 15 or more indicates that phosphorus was the limiting factor. From
such criteria it may be concluded that all of the secondary effluent,, and simulated
secondary effluent assays (Assays 1, 2, and 3) were definitely nitrogen limited;
and that with but few exceptions the tertiary effluents were phosphorus limited.
Variations in data from pond to pond in Assays k, 5, and 6 are considerable.
However, it is important to remember that phosphate concentrations were' low, and
that the assays covered a period of time when temperatures were dropping and winds
increasing. Thus it might be expected that allochthonous material would enter
the ponds on a random basis; and growth rates be temperature dependent.
-------
TABLE 4-12
N/P RATIOS IN POND ASSAYS
(values in mg/mg)
Pond
No.
2
6
3
7
4
8
2
6
3
7
1+
8
Based on Total Inorganic-N and P04-P
Assay Number
(See Table 4-l)
1
5.2
8.8
2.4
2.9
1.0
1.0
2
6.1
2.0
3-7
3.3
2.2
2,1
Based on
3.8
7.9
7.2
8.1
4.2
3.6
3.9
2.2
5-6
^.5
3,6
3.^
3
5.7
1.9
3.^
3.2
2.6
2.4
4
15-5
3.2
9.6
29«7
12.1
8.4
Soluble EH3-N
7.^
1.2
5-7
^.3
6.3
^o5
22.5
5.1
8.6
28.3
13.0
8.9
=5
27.2
14.0
106.1
15.8
M.3
19.8
6
4l.2
38.9
^3.3
25.6
48.1
126.4
and P04-P
27.4
12.2
103-5
15.3
44.J
23.0
4o.3
38.4
45.2
24.4
55-5
137.1
Materials Inventory
The term "inventory" rather than materials balance has teen used herein
because of the difficulties of making a complete mass balance in outdoor pond
assays. However, the general expectation that decreases in nutrients should
"be reflected in an increase in volatile suspended solids can "be tested from
the data presented in the foregoing tables and an estimate of the nitrogen
content of living cells. To this end Ta"ble 4_ij was prepared from data
presented in Table 4-5 (VSS) and Table 4-8 (inorganic-N) by assuming that
the observed loss in N is entirely bound up in the observed gain in VSS.
The possiblity that iron, or such trace elements Mg, Zn, Cu, Co, B, and
Mo, might be limiting was explored in Ponds 4 and 8. In Assays 1, 2, and 3, LTW
was fortified with iron and trace elements in addition to ammonia-N and P04.
During Assays 4, 5, and 6, Ponds 4 and 8 contained LTW and 1$ tertiary effluent,
plus iron and trace elements (see Table C-6, Appendix c). An examination of Table
4-5 shows an apparent small difference between Ponds 7,3 and 8,4 in Assays 4 and 5,
but none in Assay 6. In view of the variations evident throughout other assays it
cannot be concluded from the data that trace elements or iron significantly affected
the growth rate of biomass as measured by VSS.
51'
-------
TABLE 4-13
CALCULATED PERCENT INORGANIC-N IN VSS
Pond
No
2
6
3
7
4
8
Assay Number (Table 4-1)
1
4.5
7-9
7-2
8.1
4.2
3-6
2
3-9
2.2
5-6
4.5
3.6
3.4
3
7-4
1.2
5.7
4.3
6.3
4.5
4
15-5
-
6.3
57. 2a
6.1
9-2
5
14.2
4.6
4.7
24. 4a
9.8
4.1
6
6.5
3-9
4.5
6.4
4.6
5.1
Value uncertain due to operational problem
in Pond 7.
The nitrogen content of various algae as summarized in the Second Progress
Report [2] range from approximately 4 to 11 percent, although some species may be
appreciably lower and luxury uptake of nitrogen in nitrogen-rich media may lead
to higher values. A mass balance of nitrogen made on ponds during assays in
1968-1969 by the authors of this report indicated about 10 percent nitrogen in
organisms indigenous to Lake Tahoe on the basis of nitrogen vs VSS. Other observa-
tions of Scenedesmus and Ghlorella by the authors show 6 to 8 percent nitrogen on
a dry weight basis. Whipple[2l] reported the nitrogen content of Diatomaceae to
be 3.66 percent. From such general information the data in Table 4-13 might be
said to indicate a reasonably good materials balance in the nutrient - VSS conversion;
and hence that reasonable confidence in the overall results of the inventory is
justified.
Kinetic Analysis
A computer program was written to determine the rate constants and coefficients
in Equations 1 and 2 of Chapter II. This was applied to the data from Tables C-J
and C-4, Appendix C, considering each of the following nutrients or combinations of
nutrients as of possible importance: N03-W, NH3-N, Inorganic N(N03-N + NH3-N),
Total N, P04-P, and Total P. Estimates of cell mass as measured by VSS, both
observed and corrected for estimated allochthnous material, were analyzed with each
of these nutrients. The results, presented and analyzed in detail in the Third
Progress Report [jlj were disappointing in their lack of statistical significance
and reasonableness of kinetic parameters. As in the case of the flask assays, much
investigative work evidently remains to be done before the kinetic parameters
obtained with ponds can be reconciled with kinetic theory.
The reasons for this are both numerous and to a large degree controversial.
It seems quite certain that they can not. readily be resolved without greater ability
to control and evaluate all variables than can be achieved under outdoor field
conditions.
-------
Flask Assays of Fond Effluent
To a very significant degree the experimental ponds used in the study herein
reported are analagous to marinas or lagoons in which Lake Tahoe water is detained
at temperatures more favorable to algal growth than that of the lake, and is given
added nutrients as a result of human activity in the water or on the adjacent land.
In such confined waters an assay measures only the growth potential remaining at
any given tijne in the eutrophication cycle. Thus "both the growth potential and the
existing biomass would have to be measured in order to evaluate the productivity of
any given body of water. To explore the residual growth stimulating ability of
water after its original nutrients have been reduced by algal growth, flask assays
were made during steady state operation of the experimental ponds. Samples for
assay were collected from each of the eight ponds during six separate assays of
Lake Tahoe water, and three assays each of secondary and tertiary waste water
effluent during the 1969 season.
Results of these flask assays of ^8 pond samples and six Lake Tahoe
water samples are summarized in Table k-lk in which are reported values of growth
rates, cell concentration, coefficient of variation for p^ and X5, and the correlation
coefficient for p^jj. Values presented in the table for concentration of sample
represent the influent waste concentration established for the pond assay and do
not reflect the condition of the various samples drawn from the pond for flask assay.
All of the flask assays from the ponds yielded lower growth response than
did flask assays of secondary and tertiary effluent at concentrations equivalent to
that fed into the ponds for pond assay purposes. Basically the same.growth response
pattern was observed when measured by any of the three parameters, p^, M^, and X5.
The following discussion therefore applies to all of these parameters.
Examination of Table k-lk shows that little change in growth response
occurred in the pond effluent samples in comparison with that displayed by Lake
Tahoe water reference ponds undergoing pond assay. This indicates that little growth
effect is to be expected by confining Lake Tahoe water in the absence of added
nutrients. Such a circumstance, however, is of little practical consequence because
when any detention of Lake Tfjhoe water does occur, as in marinas or keys, it is
impossible to prevent the entry or accumulations of nutrients which result from the
human activity which the impoundments or developments were designed to attract.
Flask assays made from ponds operating on secondary and simulated secondary
effluents detained as long as eight days showed that there still remained enough
nutrients to support a larger biomass than normally measured in Lake Tahoe water.
This means, of course, that the growth of organisms during pond bioassays did not
strip out enough of the added nutrients to restore Lake Tahoe water to its original
degree of purity. Interpreted in terms of lake conditions this would mean that
even harvesting of algae from an enriched confined water by chemical precipitation,
for example, would not prevent a residue of the nutrient which produced the growth
from moving out into the lake.
Flask assays of samples from theponds in assays U and 5 and receiving low
concentrations of tertiary effluent produced little growth for the simple reason
that the tertiary effluent had previously been subjected to both phosphate removal
and a growth of organisms under phosphate limited conditions. Thus no residual
ability of the pond effluent to support algal growth was identified. This apparent
result, however, is misleading because in the phosphorus poor water nitrogen was
not utilized and so remained in the flask.. Again in terms of a nitrogen sensitive
lake, the flask assay represented a situation in which a critical nutrient could be
discharged to Lake Tahoe undetected by an assay based on growth stimulating potential.
From Pond Assay 6 the flask assay showed a residual nutrient concentration
sufficient to support growth beyond the level found in Lake Tahoe water. The reason
for this difference between results on Assay 6, and Assays h and 5 lies in the
factor of temperature. Pond Assay 6 was conducted at the lowest temperatureof all
assays hence growth in the ponds was inhibited. At the optimum temperature used in
53
-------
MAXIMUM GROWTH RATES, i^ and pb(, AND MAXIMUM CELL CONCENTRATION, X3,
ATTAINED AT THE END OF FIVE DAYS IN FLASK CULTURE OF POND
SAMPLES COLLECTED DURING STEADY STATE OPERATION
Sampling
Dote,
Pond and
Assay
No.
8- 6-69
Assay 1
Pond 1
2
5
k
5
6
7
8
LTW
B-20-6y
Aeoey 2
Pond 1
2
3
It
5
6
7
8
LTV
9- 2-69
Aaeey 3
Pond 1
8
3
l<
5
6
7
8
LTW
10- 1-69
Aeeay *t
Pond 1
2
3
I*
5
6
7
8
LTW
10 -lit -69
Assay 5
Pond 1
2
3
t
5
6
7
8
LTH
10-27-69
Assay 6
Pond 1
2
3
!;
5
6
7
8
LTH
Source and
Sample
(*)
LTHB i,
o.i* nb
1.0* IIC
i.o* s-ir
LTW
0.1* II
1.0* II
1.0* S-II
Headere
LTW
0.1* II
1.0* II
1.0* S-II
LTV
0.1* II
1.0* II
1.0* S-II
Header
LTW
0.1* II
1.0* II
1.0* S-II
LTV
0.1* II
1.0* II
1.0* S-II
Header
LTV
?* ii i:
1* IIIs
1* III + TTT
LTW
2* III
1* III
1* III * TE
Header
LTW
S* III
1* III
1* 111 + TE
LTW
2* III
1* III
1* III + TE
Header
LTW
2* III
1* III
ii in + TE
LTW
2* III
1* III
1* III + TE
Header
Mean Hex.
Rate
V)
0.147
0.153
0.243
0.508
0.140
0.105
0.423
0.1459
0.142
0.068
o.o'o
0.254
o.364
0.092
0.06k
0.061
0.127
0.171
O.lil6
0.408
0.576
0.422
0.436
0.299
0.416
0.512
0.589
0.206
0.359
0.260
0.163
0.416
0.355
O.?15
0.432
0,462
0.545
0.1J9
0.569
0.550
0.447
0.369
0.1151
0.1132
0.379
0.225
0.191
0.599
0.119
0.160
0.623
0.20^
0.231
0.125
Coef.
Var.
W)
27.0
35.5
9.4
11.8
25.3
12.1
7.6
8.1
32.1
111!. 5
79.5
7.6
18.6
26.9
31.8
66.8
"i7.3
54.5
6.0
9.5
11.2
22.7
15.2
18.6
57.6
10.1
9.2
29.1
20.1
21.6
25.6
24. k
20.1
58.6
55.3
18.0
5.8
13.6
5.8
10.3
22.7
13.4
32.3
20.6
19. 1
15.3
58.9
5.4
66.9
57.0
13.5
18. S
16.1
21.2
Mean Hex.
Rete
/.,
day'1)
0.064
0.071!
0.168
0.29>»
O.OBli
- 0.018
0.255
0.244
0.017
0.027
- 0.019
0.156
0.218
0.064
0.043
0.027
0.082
0.107
0.317
0.299
0.354
0.319
0.276
0.198
0.237
0.325
0.368
0.050
0.179
0.118
0.133
0.251
0.153
0.120
0.274
0.265
0.347
0.3*12
0.365
0.384
0.311
0.256
0.301
0.312
0.245
0.139
0.118
0.408
0.077
0.065
0.357
0.137
0.157
0.098
Corr.
Coef.
0.521
0.625
0.939
0.912
0.757
- 0.256
0.928
0.874
0.201
0.453
- 0.348
0.931
0.921
0.931
0.834
0.384
0.718
0.765
0.958
0.967
0.906
0.959
0.911
0.948
0.554
0.937
0.932
0.312
0.646
0.790
0.883
0.837
0.766
0.740
0.613
0.792
0.944
0.977
0.946
0.961
0.937
0.952
0.916
0.962
0.932
0.923
0.854
0.961
0.806
0.712
0.909
0.938
0.949
0.842
Cell Cone.
8=
(eella/
,S)
115.1
125.4
174.1
285.3
116.1
79.2
248.7
246.4
92.5
99.1
96.2
142.4
189.6
96.2
93.3
104.7
115.8
117.7
179.0
180.1
320.1
220.1
167.3
117.1
392.8
467.6
221.6
90.9
119.1
96.2
100.5
.186.4
104.5
93.3
182.2
146.9
210.6
192.7
207.5
204.4
207.7
152.6
232-9
205.4
312.0
252.5
222.6
693.8
170.2
215.4
643.0
218.0
174.6
176.2
Coef.
Var.
(*)
30.5
21.5
13.1
10.1
16.8
6.9
4.9
13.7
7.8
5-3
2.0
6.2
5.5
4.4
4.2
8.4
23.8
26.5
20.4
11.8
14.6
10.6
22.5
4.1
53.3
12.9
7.6
26.7
11.3
11.4
20.5
18.0
13.1
17.0
44.1
25.4
7.7
8.7
5.8
10.7
19.7
10.5
21.7
5-9
10.9
5.0
10.7
8.8
16.9
6.9
15.1
5.5
4.2
7.8
LTW - Pond containing only Lnhe Tehee wa
0.1* II - Pond containing 0.1* secondary
C1.0* II - 1* secondary eevage effluent In LTV.
1.0* S-II - 1* simulated secondary aevage effluent (refer to Table C-6, App
eHeader - Water sample collected from pond influent LTH eupply header.
2* III - Pond containing 2* tertiary eevage effluent from BTPUD Hater RecLa
gl* III - 1* tertiary oevage effluent in LTH.
Table c-6, AppendiJt c).
t from STPUD Water Reclamation Plant and LTW.
n Plant and LTH.
flask assays, however, algae were able to utilize nutrients which their predecessors
in the ponds could not. In terms of lake conditions this could mean that nutrients
reaching embayed waters during the cold months could accumulate and then support an
algal bloom in the spring. Such a bloom would, of course, disappear with the
stripping of nutrients; but by that time the nutrients are in the cycle of growth,
decay, and recycle; and eutrophication is advanced thereby.
-------
CHAPTER V
ASSAY OF SURFACE WATERS
INTRODUCTION
To evaluate the danger to Lake Tahoe of man's development and occupancy of
land in the Basin (Objective No. 3, Chapter l) a program of systematic sampling and
assaying of Lake Tahoe and creek waters was initiated in 1967. For continuous
monitoring throughout the study, Ward Creek, Incline Creek, and the Upper Truckee-
Trout Creek system were selected as representing surface runoff from relatively
undeveloped, newly developed, and well established urban development, respectively.
Later, in 1970, General Creek was added to the list to represent undeveloped land,
as the Ward Creek watershed was at that time being subjected to considerable land
development activity. By comparing the nutrient content and growth stimulating
properties of water from these U major creeks, utilizing Lake Tahoe water as a
background or Control, a great deal was revealed concerning the threat of eutrophica-
tion resulting from land development. Findings of this aspect of the assay of sur-
face waters are the subject of this chapter (Chapter V). During the 1969-70 grant
period a program of analyses and bioassays of some 27 additional creeks was begun
in order to evaluate the non-sewage contribution of nutrients to Lake Tahoe. Such
an evaluation, based on the overall findings of the study, is the subject of
Chapter VI.
QUALITY OF LAKE TAHOE WATER
Chemical Analyses
Because Lake Tahoe is a relatively large body of water (approximately 21
miles long and 12 miles wide) the question of obtaining a representative sample
immediately confronts the investigator. Samples for chemical and biological assays
were taken therefore both from a point near mid-lake and at the near-shore location
from, which lake water was pumped for the pond assays described in Chapter IV.
Results of physical and chemical analyses of lake water samples from these two
stations for the period June 1967 through November 1970 are presented in Table D-l,
Appendix D. From a plotting of near-shore and mid-lake data reported in 1969(3)
it was found that the two were,not significantly different on any particular
sampling date. Subsequently; in 1970, this observation was further verified by a
short-term program of sampling at multiple points around the lake. The similarity
evident for the more conservative nutrients such as P04-P, Total nitrogen, and
(N03+ N02)-N , however, showed a seasonal variation.
Although both mid-lake and near-shore data are presented in Table D-l, only
near-shore data are plotted in Figure 5-1 The figure shows that during the period
of study the Total nitrogen was predominantly organic nitrogen. In 1968 and 1969
there was a high peak in the curves in the October-November period, with a moderate
rise in Total-N due to a peak in the ammonia nitrogen concentration in March 1969.
The 1969 and. 1970 curves show a rise in mid-summer which was not evident in 1968.
Ammonia-N and (N03 + N02)-N concentrations in Lake Tahoe (Figure 5-l)
followed a similar but less clear pattern, with explosive changes in ammonia
appearing in January and March of one season, and in January and June the following
year. In November 1970 a sharp rise in both NH3 - N and (N03 + N02)-N gave an
upward trend to the Total-N curve.
Total phosphorus showed a more consistent pattern of seasonal peaks than
did nitrogen, with January and May being the typical peak periods.
From the nitrogen and phosphorus curves in Figure 5-1 it seems evident
that seasonal changes in the nutrient content of Lake Tahoe water do occur. That
these changes are not simply the result of wind disturbance of sediments in the
-------
FIGURE 5-1 RELATIONSHIP OF GROWTH PARAMETERS AND NUTRIENTS, NEAR-SHORE LAKE TAHOE
-------
shallows was shown in a previous report (3) which revealed the same variations to
prevail simultaneously in mid-lake and near-shore waters. This led to the
conclusion that for the purpose of the study the near-shore samples were typical
of Lake Tahoe Water.
That the observed seasonal differences do not represent nutrient depletion
by biomass production is evidenced by the tendency of peak concentrations to occur
during seasons when a maximum of nutrient tieup in living cells might be expected.
In evaluating the curves, however, it should be borne in mind that the concentra-
tion of nutrients in Figure 5-1 is expressed in \j.g/& and therefore represents quite
small amounts of chemicals even at peak values.
Growth Response
Results of flask assays of the growth response of Selenastrum are
summarized in Table D-2, Appendix D. Values of three growth parameters in this
table (jv> U, , and Xs) are plotted in Figure 5-1 on the same scale of time as the
nutrient concentrations. On July 1, 1969 there was a distinct break in continuity
of the curves as the test alga was changed from S. gracile to S. capricornutum
and the Coulter Counter was substituted for ocular (hand) counting of cells under
the microscope. With either organism, tu seemed a somewhat more sensitive para-
meter than IL or maximum cell concentration, X5, during 1968-69. In 1969-70, this
tendency was only slightly evident, if not indeed non-existant.
In general, the growth rate of S. c apr i c ornutum showed a tendency to
fluctuate with the total nitrogen and the organic nitrogen concentration and was
little related to the phosphorus content. This observation supports the recurring
evidence that Lake Tahoe is nitrogen sensitive.
During 1968 and the early months of 1969, when S. gracile was the test
alga, the relationship of growth rates to nutrients is unclear. The reasons for
this difference in observable relationships are threefold. First, at the low
levels of nutrient present in Lake Tahoe water, normal experimental error of a few
micrograms may appear as a large percentage variation. Second, the analytical
skill of personnel improved with time and experience with low concentration
samples. Third, and perhaps most important, the Coulter Counter permitted rapid
analysis (approximately 13 seconds per count), thus permitting a great many more
replications of counts on a single sample than is feasible with an analyst using
the microscope. Thus it is concluded that the greater accuracy of both man and
machine showed up subtle relationships in 1969-70 that were difficult to detect
under previous conditions.
The break in the growth curves in mid-1969 is an indication of a difference
in response of S. gracile and S. capricornutum, plus or minus any changes in
accuracy of method. It is interesting to note that the maximum growth rate of
S. gracile during the 1968-69 period tended to average about the same as the 29
percent per day observed in the early survey results reported in Chapter III. With
S. capricornutum in 1969-70, the average appears by simple visual examination of
Figure 5-1 to be about 20 percent per day (0.2 day"1). It is also noteworthy that
with the Coulter Counter, the two measures of growth rate (pb, p^) differed little,
although, as previously noted, jj^ continued to show on occasion slightly higher
growth rates than other parameters. The response in terms of the cell count, X5,
although expressed in different terms and on a different scale in Figure 5-1,
followed the same pattern as did ^ and p^. This indicates that cell count alone
is a feasible parameter of growth stimulating potential at the low cell concentration
levels attained in LTW.
57
-------
Evaluating Results
In interpreting the growth rate and nutrient relationships in Figure 5-lj
it important to recall that the nutrient analyses and flask assays reported were
"both made on water from which indigenous organisms had been removed by filtration.
Thus "both reflect the residual potential of Lake Tahoe water during or after the
occurrence of any indigenous growth under lake conditions. Some fraction of the
nutrients in LTW may, therefore, have been tied up in living cells or undegraded
organic solids when the flask assays were made, especially in the summer season.
Evidence that this phenomenon can lead to serious misinterpretation of data was
suggested in Chapter III in comparing the growth rate of S. gracile observed in
flask assays of a few marinas and keys (Table 3-3) with the growth rate observed
in Lake Tahoe water (Table 3-l) under similar conditions. In isolated observations
not herein tabulated, extensive growths of attached algae were observed growing in
a marina in which the water understandably showed very limited ability at that time
to support growth in flask assays .
To evaluate the degree to which the results of flask assays of either mid-
lake or near-shore waters represent the true eutrophication potential of nutrients
in the Lake it is necessary to examine the seasonal variation in VSS in LTW" for
both the flask and pond assays. A wide fluctuation in VSS and nutrients between
winter and summer seasons would be expected of eutrophic waters under the seasonal
variation in climatic conditions prevailing at Lake Tahoe. On the other hand a
completely oligotrophic water should remain quite constant in VSS and nutrient
concentrations except at times of sediment disturbance by storms or influx of
surface wash.
Table D-l (Appendix D) shows that during the Jan.-Dec. 1970 period, when
VSS measurements were made of LTW", the biomass, as measured by that parameter, was
continuously low. Only on 3 occasions was a value greater than 1 mg/.# VSS observed
in near-shore waters, where variations in suspended matter are more profound than
elsewhere in the lake.
On each of these occasions (January, May, and July) the total suspended
solids were vastly greater than normal, as was the ratio of total-to-suspended
VSS. Each is explainable by one of the phenomena which have been observed to
create such conditions, i.e. l) storm runoff carrying sediments stripped from
disturbed soil, and 2) wind or storm disturbance of the sediments on the lake
bottom in shallow water. In this particular case an exceptionally severe storm
occurred in January; a snowmelt took place in May; and in July a strong wind
traversing the lake from south to north produced a profound disturbance of the
bottom sediments in the area of near-shore sampling at North Tahoe.
Table C-^ (Appendix C) shows that on two other occasions (in 1969) values
of volatile solids were greater than 1 mg/,0. On one of these occasions (Oct. 8,
1969) a sudden explosive rise in solids at the near-shore sampling station (see
Figure 4-3, Chapter IV) was wind generated [3] during a storm. Unfortunately, the
dangers and difficulties of mid-lake sampling during high wind or storm periods
prevented a securing of comparative mid- and near-shore data on the four occasions
cited.
In five instances when mid- and near-shore lake sampling was done on the
same day (i.e. 8/4, 8/26, 9/29, 11/2, and 11/23, 1970) (see Table D-l) there was
a clear tendency for:
1. VSS and Total SS concentrations at mid-lake to be identical.
2. Total SS concentration to be somewhat larger than VSS in near-shore
samples.
3- The solids in near-shore samples to exceed those at mid-lake.
-------
Such data are rationally to be expected because sedimentation is a near-shore
phenomenon; disturbance of sediments by water movement is greatest in shallov
water; and the abundance of life, whether in lakes, estuaries, or the ocean, is
greatest in the near-shore zone.
The foregoing findings suggest that flask assays of the near-shore samples
should reflect a residual growth-stimulating potential somewhat less than appears
in the lake in general. Examination of the chemical analyses of mid- and near-
shore waters in Table D-l reveals some evidence to support this suggestion. In
four of the five situations cited in the preceding paragraph the Total-N at mid-
lake exceeded that at the near-shore station. P04-P was likewise higher at mid-
lake in if- of 5 instances. Both of these facts would indicate conditions less
favorable to algal growth at mid-lake than near the shore.
The question as to whether this expected difference in mid- and near-shore
lake water characteristics is of any significance when the growth response in LTW
is used as a control, and LW is used to dilute other waters for assay purposes,
can be answered by considering several facts. First as shown in Table D-l there is
no identifiable seasonal pattern in the biomass as measured by VSS in 1970, except
perhaps a modest peak during the month of July which bore little if any relation
to nutrient content reported. Next, growth rates in Figure 5-1, particularly ft^
and X5 showed a decline in the winter season in 1968-69 when outdoor conditions
are least favorable to indigenous growth, and consequently nutrients should be,
and were, in greatest abundance. Moreover, mid-lake growth rates reported in Table
D-2 (Appendix D) and in Table 5-1, show that although values fluctuated somewhat
more widely than did near-shore rates, there was no identifiable seasonal trends;
and the general average was not observably different for the two locations.
Considerations such as the foregoing supported the conclusion that near-
shore samples taken at the site of the pump intake used in the Pond Assays were
representative of the upper stratum of Lake Tahoe and suitable as a background
against which to compare the growth response of creek waters in flask assays.
This conclusion, of course, added further validity to the results reported in
Chapters III and IV in which it was shown that several types of possible inputs to
Lake Tahoe exceed LTW in algal growth stimulating potential; and that sewage
effluent in Lake Tahoe would produce algal growth in proportion to the concentration
of effluent until limited "by some growth factor.
QUALITY OF CKEEK WATERS
Chemical Analyses
Table D-3 of Appendix D reports the results of chemical and related
analyses of samples from Ward, Incline, and Upper Truckee- Trout Creek for the
period June 1968 through November 1970; and for General Creek from July through
November 1970. Data from this table are plotted in a series of figures hereinafter
presented to show the variation in several parameters of quality throughout the
period of study.
Inorganic Nitrogen Series. Figure 5-2 shows the relationship and the
variation with time of three forms of soluble nitrogen in Creek Waters. From
an examination of the curves for NH3-N it seems likely that both the activities of
man in the Lake Tahoe Basin and seasonal variations are reflected in the curves.
Incline Creek, draining an area which was undergoing land development, particularly
in 1968 and 1969, shows a pattern of comparatively high concentrations of ammonia
seasonally. In both 1968 and 1969 a peak in the curve appeared in September. In
1970 this summer peak occurred about two months earlier. In February 1969 and 1970
and again in April 1970, Incline Creek reached a peak value at a time when the
ammonia content of both Ward and. Truckee Trout Creeks was declining. High peaks
occurred in both April 1969 and April 1970. As previously suggested [3], this
annual peak may well have resulted from surface runoff occurring at a time when
59
-------
fertilizing of a golf course through vhichIncline Creek flovs might he appropriate.
However, no specific data on this point are at hand.
In April 1969 all three creeks shoved a rise in MH3-W at the time
of melting of an unusually heavy snov pack. The milder winter which followed did
not produce a similar rise in the ammonia content of Ward and Truckee Trout
Creeks in April 1970. The presumptive evidence., therefore is that a climatological
and seasonal factor is involved. Such a seasonal effect is further supported "by
the tendency of all three creeks to show essentially the same concentration of
HH3-W in the winter (Nov.-Dec.) season. However, this is also the season when
man's activities on the drainage area has the minimum of effect, and when temper-
atures are not conducive to the "biodegradation of organic matter that produces
ammonia.
With the exception of the high peaks in HH3-N in Incline Creek in mid- or
late -summer there was some tendency for all creeks to behave alike during the dry
summer months, just as in the winter.
On the basis of the 1968-69 data it was concluded in 1969 (j) that the
NH3-N curves of Figure 5-2 showed quite clearly that active development of land
released nutrients far in excess of that to be expected from undisturbed land.
It was stated (j>) that "...If the Ward Creek data are assumed to reflect what might
be expected under natural conditions, the NH3-W concentration in April was about
doubled by human activity on the Upper Truckee Trout drainage area,and increased
by a factor of eight by activity in the Incline Creek basin." Reviewing the data
(Figure 5~2) for March-April period of 1970 leads again to essentially that same
conclusion.
Examination of the KH3-N curves from May to December 1970, however,
suggests that a longer period of observation is in order. During that period,
development of the Ward Creek Basin began. Thereafter, for the first time Ward
Creek became essentially like Upper Truckee Trout Creek in ammonia content, and
exhibited even higher peaks than the latter during the summer. This effect of
human activity was made further evident by comparing Ward Creek with General
Creek, which was added to the list in July because of the more natural state of
the land in its drainage area. As the winter season approached, the tendency of
all four creeks to behave alike at that season in terms of HH3-N again appeared.
Although on the basis of the HH3-W curves there is little doubt that land
development activity in the Ward Creek watershed increased its nutrient content,
data for another season or two are needed to determine whether it will react as
explosively as did Incline Creek. There are some reasons to suggest that it may
more quietly assume the status of Upper Truckee Trout Creek. These lie in a
greater public awareness of the problems associated with land development and more
strict institutional controls of land development procedures.
In the case of Incline Creek the data from May to December 1970 seems to
suggest that as its land development is completed it, too, may become more like
Truckee Trout in its nutrient contribution to Lake Tahoe. Again it will require
another two years of data to determine whether under more watchful management and
maturing of the development itself the explosive concentrations of NH3-W of past
years will not reoccur. Possibly the curves reflect only the effect of an early
Fall season in 1970, but the alternate possibility of a more limited contribution of
nutrients to the Lake can not be discounted until the record is clarified by future
observations.
(N0g + M03)-N. The plot of values of nitrite plus nitrate nigrogen in
Figure 5-2 shows for Incline Creek the same pattern of values as observed for
ammonia in 1969. In early 1970, however, the high peak for oxidized nitrogen
preceded by two months the high point in KH3-N- Whereas in 1969 the two peaks
were coincident. One possible reason for this phenomenon is the difference in
weather cycles of the two years. 1968-69 was a winter of excessive snow which
60
-------
was slow in melting. In January 1970, however, there was excessive rainfall,
followed "by snow which melted later. Fertilizing practice evidently differed in
the Incline Creek watershed for the two years. In early February 1969 the ratio
of NH3-N to (N02 + W03)-N was l.J/1; and in April, 1.66/1. In contrast the
corresponding values in 1970 were about 0.6/1 and 12.8/1, respectively, with only
the April MH3-N values for the two years being of comparable magnitude. The
mid-summer peaks in ammonia and oxidized nitrogen concentrations coincided in
1970 just as they did in September 1969, but the values were much smaller, thus
supporting again the possibility that Incline Creek may decline in its future
nutrient content.
Although it is unclear just why the peak concentrations of nitrogen
differed in the two years of study, their magnitude in comparison with that of
Ward and Truckee - Trout Creeks leaves no doubt that human activity was the source
of the nutrient. In both years of study Upper Truckee - Trout Creek showed an
appreciable rise in the more stable forms of nitrogen as the fall of the year set
in. However, one need only observe the watershed area to conclude that the Truckee
- Trout system reflects in its nutrient content the presence of humans. In the
matter of (N02 + N03)-N, Ward Creek remained similar throughout the period of
study, exhibiting in ammonia content its principal nitrogen response to land
development.
Curves for Inorganic -W, being the summation of thfe NH3-N and (W02 + N03)-N
concentrations, show little that has not already been discussed in relation to
Figure 5-2-
Organic and Total Nitrogen. Figure 5-3 shows that in February and April
1969, the nitrogen content of Incline Creek included soluble organic nitrogen
as well as ammonia and (WOg - N03)-N- In 1970, however, organic nitrogen was
associated only with the (NOg + N03)-N rise in February. Thereafter it fluctuated
throughout the summer and early fall. Upper Truckee - Trout Creek, after a high
rise in February 1970, fluctuated throughout the summer, then rose sharply in
September but to a level of only about one-half of its similar fall peak in 1969.
Ward and General creeks were similar in their low values of organic nitrogen,
presumably due to less disturbed land conditions on their watersheds.
The total nitrogen curves in Figure 5~3 show no phenomenon not previously
considered in relation to the nitrogen fractions which are summed up to produce
them.
Ortho and Total Phosphorus. The P04-P and Total-P values reported in
Table D-3 (Appendix D) are presented graphically in Figure 5-4. As in the case
of nitrogen two very sharp peaks are apparent for Incline Creek in 'February and
April 1969, indicating that some more balanced fertilizer than nitrogen alone
was present in the creek on the sampling dates reported. In 1970 the P04-P rise
was associated in February with peak values of (N0a + W03)-N and Organic N. It
coincided with the July peaks of NH3-N and other nitrogen compounds but was near
its lowest observed level when the exceptionally large concentration (536 M6/-0)
of ammonia appeared in Incline Creek in April 1970 (see Figure 5-2). Throughout
the entire period reported Incline Creek carried a higher concentration of P04-P
than any other of the four creeks monitored. In contrast Upper Truckee Trout
Creek was lowest in P04-P content a great portion of the time. On the assumptions
that Ward and General creeks represent the somewhat normal case, the conclusion is
inescapable that human occupancy of the newly developed Incline area increased the
contribution of soluble ortho-phosphate, whereas on the more stabilized watershed
of Truckee Trout the effect was to reduce P04-P.
61
-------
I [
a WARD
O INCLINE
o UPPER TRUCKEE-TROUT
O GENERAL
o o
JUN JUL AUG SEPT OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC I JAN FES MAR APR MAY JUN JUL AUG'SEP OCT NOV DEC
1968 1969 1970
FIGURE 5-2. VARIATION IN CONCENTRATION OF NITROGEN COMPOUNDS
IN CREEK WATERS
62
-------
(jo
A WARD
O INCLINE
Q UPPER TRUCKEE-TROUT
O GENERAL
JUN JUL AUG SEP OCT NOV DEC | JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC | JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
1968 1969 1970
TIME
1000
JUN JUL AUG SEP OCT NOV DEC | JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
1968 1969 1970
TIME
FIGURE 5-3. VARIATION IN ORGANIC AND TOTAL NITROGEN IN CREEK WATERS
-------
1 I 1 1 1
1 1 1 1 I 1 I I 1
A WARD
O INCLINE
D UPPER TRUCKEE-TROUT
O GENERAL
JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT MOV DEC ] JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
1968 1969 1970
TIME
JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
1968
1969
1970
TIME
FIGURE 5-4. VARIATION IN P04-P AND TOTAL P IN CREEK WATERS
-------
Total -P followed the same pattern as P04-P with the exception that in
September each year Incline Creek showed a very high concentration of Total -P
which was obviously not ortho-phosphate. It was postulated in 1969 (3) that the
unusual amount of Total -P in upper Truckee Trout Creek in that year was the
result of some unusual discharge to the creek. The failure of Truckee - Trout
to show a similar rise in the fall season of 1970 supports such a possibility.
Following the beginning of development of the Ward Creek basin in"1970 it
showed an increase in Total -P not apparent in 1969 nor in the P04-P curve of
Figure 5-4.
All of these several observations are explainable, although the data to
document any individual explanation are not at hand. Fertilization of grass and
landscaping, together with the disturbance of soil cover, can readily account for
most of the nitrogen and P04-P relationship and variations reported. The source
of total phosphorus not in the ortho state is presumably the degradation of vege-
tation ^ as leaves and pollen, well known storehouses of phosphorus, are broken down
to a soluble organic state. Tables of Chapter VI show that an increase in total
phosphorus in the late summer and fall is characteristic of creeks in general
in the Tahoe basin.
Other Water Quality Factors. Values of such water quality factors as
calcium, conductivity, iron, chlorides, pH, and alkalinity are plotted in
Figure 5~5- The various curves indicate that in general all creeks followed similar
seasonal patterns. Chlorides in Incline Creek showed two fairly sharp peaks in
February and April 1968 paralleling what occurred in the nitrogen and phosphorus
series . However, there was a tendency for Upper Truckee Trout Creek to show the
highest concentrations of chlorides throuhout the period of study. A particularly
sharp rise above normal limits appeared in the Truckee Trout system in the fall
of 1970. ,Because the Truckee Trout basin is a populated area and because of the
use of salt to reduce ice on pavement, it is to be expected that chlorides will
be one of the important quality degrading factors contributed by human activity
in the Lake Tahoe Basin, althouth it is not a factor in eutrophication at the levels
presently found.
Total and Volatile Suspended Solids. Values of Total and VSS reported in
Table D-3 (Appendix D) are summarized in Figure 5~5 for the year 1970. They show
strikingly the disparity between Incline Creek and other creeks. Of particular
significance is the increase in both volatile and suspended solids during the
construction period, beginning immediately following a heavy rain in June and
extending through the dry summer months to the end of September. Although the
values reported do not represent especially turbid water, they do show up some
differences between the surface runoff from developing, developed, and undisturbed
natural land conditions.
GROWTH RESPONSE IN CREEK WATERS
The results of flask assays of undiluted samples of creek waters are
presented in Table D-4, Appendix D. From these data the growth rates p^ and p^
and the cell concentration X5, were computed for Incline, Ward and Upper Truckee
Trout creeks for the period of study (1968-70) and for General Creek for the latter
half of 1970. Figure 5~7 shows the temporal variation in values of the three
measures of algal growth response. As in the case of Lake Tahoe water which served
as a control, ocular (hard) counting of cells of S. gracile was utilized (see
Chapter II) from June 1968 to July 1, 1969. Thereafter the Coulter Counter was
applied and S. capricornutum was the test alga used. The effect of the change
over in counting method and test organism is apparent in Figure 5-7 just as it
is in Figure 5-1 (Lake Tahoe Water).
As in the case of assays of LTW, the three measures of growth response
(Figure 5-7) followed essentially the same pattern of seasonal variation. By
65
-------
65
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NW DEC
1969 1970
TIME
FIGURE 5-5. VARIATION IN CONCENTRATION OF SELECTED
WATER QUALITY FACTORS IN CREEK WATERS
66
-------
A WARD
O INCLINE
D UPPER TRUCKEE-TROUT
0 GENERAL
JAN FEB MAR APR
MAY JUN JUL AUG SEPT OCT
TIME .days, 1970
NOV DEC
FIGURE 5-6. VARIATION IN SUSPENDED SOLIDS AND VOLATILE
SUSPENDED SOLIDS IN CREEK WATERS
-------
any measure Incline Creek was by far the most productive of algal grovth prior to
mid-summer 1970. Truckee Trout was next in order and during 1968 did not differ
much from Incline. Both were generally more productive than Ward Creek during
the 1968 period.
Throughout the year 1969 there was a spectacular difference in cell con-
centration, X5, "between Ward Creek at the lower extreme and Incline Creek at the
upper. Except at the time of an explosive rise in Incline Creek in April 1969
the Truckee - Trout system was not spectacularly lower in growth response than
Incline Creek in terms of cell concentration. Essentially the same may be said
of the growth rate as measured by l^ft, with one notable exception. Following
the change to S . capricornutum on July 1, 1969 there was no particular difference
in the growth response of the three creeks as measured by T^ during the fall
season of 1969. A similar situation applied to pfe during the fall of 1969 except
that Truckee - Trout was appreciably higher than the other two during one month.
Prior to July 1969, however, ft^ did^not reveal the consistent difference in growth
rates evident in either the pbJJ or X5 curves (Figure 5~7)-
From January to July 1970 Incline Creek again showed the highest growth
response as measured by all three parameters. Truckee Trout and Ward creeks
alternated somewhat for second position from month to month, but all three parameters
(£b> MbA? an(3- xs) showed essentially the same pattern. From July to December 1970
cell concentrations were low in all creeks and although the number of all fluctuated
from month to month count alone could not be said to differentiate one creek from
another until December, 1970, at which time Truckee Trout and Incline, in that
order, greatly exceeded the other ^ creeks in growth response .
Both fi n and p^ detected an appreciable increase in growth rate in Incline
Creek in early September (1970) which was not revealed by the cell concentration
curve .
Relation of Growth Response to Nutrients
A comparison of Figure 5-7 with Figures 5-2 to 5-5 shows that during 1968
and 1969 the growth responses in Incline Creek corresponded very well with
increases and decreases in concentrations of HH3-W, (NOa + W03)-N, total inorganic
nitrogen, Total nitrogen, and total phosphorus. P04-P showed little relation to
growth response during the 1968-69 period and no apparent growth response resulted
from a slight rise in the nitrogen and phosphorus in December 1969- There was
little apparent correlation between changes in constituent concentrations and growth
response in Upper Truckee Trout creek; and none at all in Ward Creek.
The rapid growth rate in Incline Creek in the January to May period of 1970
is related to a similar pattern in concentration of (WOa + N03)-N, Total -N, organic
nitrogen, Total -P, and P04-P. NH3-N (Figure 5-2) showed an increase at that time
but its effect alone can not be suggested because the growth by all parameters
fail to reflect any growth response to the inorganic nitrogen and the very high
NH3-N content of Incline Creek at the end of April, 1970. The factors involved
in the less spectacular algal growth rates in Incline Creek during the period May
to September are not quite so clear- However, Total -N, KH3-N, organic nitrogen,
and Total -P were adequate for growth during that period. During the final 6
months of 1970, JTotal -N, organic N, ffl3~N, and P04-P, fluctuated in the same
pattern as did (3^, particularly. Thus it is evident that the growth response of
Incline Creek was well correlated to available nutrients. Like NH3-N in April, a
very large rise in Total -P in August -September 1970 had no observable effect on
the growth response of Incline Creek.
The growth pattern of upper Truckee Trout Creek, especially as measured
"by ft^ and ft]D, corresponded well to the increases and decreases in Total -N, P04-P,
organic nitrogen, and MH3-N. The same was essentially the case with Ward Creek.
-------
0 N D
0 H D
FIGURE 5-7. COMPARISON OF ALGAL GROWTH RESPONSE PARAMETERS IN FLASK
ASSAYS OF CREEK WATERS
69
-------
o
TABLE 5-1
SUMMARY OF THE RANGE OF ALGAL GROWTH RESPONSE IN CREEK WATERS AND LTW
Year
1968
1969
Jan.
to
July
1969
July
to
Dec.
1970
Source of Sample
Near Shorea
Ward Creek
Incline Creek
Upper Truckee-Trout Creek
Hear Shore3
Ward Creek
Incline Creek
Upper Truckee-Trout Creek
Near Shore
Ward Creek
Incline Creek
Upper Truckee-Trout Creek
Near Shoreb
Ward Creek
Incline Creek
Upper Truckee-Trout Creek
General Creek
Range of Growth
^b
days "1
Mean
0.389
0.497
0;665
0.645
0.^90
0.541
0.748
0-556
0.287
0-537
0.565
0.522
0.228
0.29*1
0.356
0.315
0-337
Min
0.22
0.192
0.508
0.^50
0.372
0.395
0.528
0.432
0.135
0.280
0-379
0.219
0.127
0.131
0.044
0.093
0.140
Max
0.634
0.926
0.842
0.824
0.640
-0 . 701
1.168
0.769
0.571
0.736
0.705
0.910
0-337
0.606
1.033
O.6i4
0.589
VbH
days -1
Mean
0.254
0.260
0.4o8
0.408
0.303
0-317
0.495
0-395
0.176
0.343
0-359
0.296
0.145
0.189
0.225
0.188
0.203
Min
0.207
0.166
0.247
0.332
0.220
0.246
0.250
0.264
0.110
0.190
0.276
0.107
0.017
0.079
o.oi4
0.058
0.087
Max
0.336
0.432
0.495
0.519
0.360
0.463
0.962
0.683
0.349
0.451
0.509
0.495
0.283
0.413
0.663
0.366
0.367
X5
cells /mm3
Mean
147-6
161.0
295.4
290.2
150.8
158.3
574-7
355-8
147.2
252.7
4i6-9
283.0
115.4
137-3
251.6
158.5
127-6
Min
13
57-2
155-0
153-2
102.6
107-8
129.6
140.4
90.0
154.9
177-4
103.0
59-6
69-3
57-3
69-7
74.4
Max
304
290.6
448.6
443.6
223.0
189.6
1812.8
1072.0
263-9
315-9
1092.0
524.8
156.2
247-3
2134.8
403-5
202-9
a Selenastrum gracile used as a test organism.
'k Selenastrum capricornutum substituted for S. gracile at this sampling point.
-------
General Creek as measured by ^ showed a growth response well related to
organic nitrogen and Total -P, but little related to other nutrient parameters . In
terms of cell concentration the pattern of growth follows that of Total -N,
(NOa + N03)-N, and Total -P- Thus, as might be expected of a creek draining an
essentially undisturbed land environment, the algal growth in General Creek was re-
lated to the stabilized forms of nitrogen and phosphorus in sharp contrast with
Incline Creek and to some degree Truckee Trout Creek, where ammonia and ortho-
phosphate were among the major stimulants .
In growth response as well as in nutrient concentration the final 6 months
of 1970 suggests that there may be a tendency for all creeks to approach some
similar equilibrium. Once again, however, it may be simply a seasonal phenomenon
as creeks have been noted to be similar during past winters. Only observations
through subsequent seasons can provide the answer-
In comparing the growth response curves for j^, jj^ , and X5 in Figure 5~7,
and especially in relating these growth response curves to the nutrient curves in
Figures 5-2 to 5~5> it is clear that jj^ and X5 were the best measures of growth
response Alternate approaches to data interpretation could change the value of jl
and might improve its correlation with nutrient in water. A discussion of these
alternatives is beyond the scope of this report. As a basis for comparing LW with
creek waters, therefore, p^ and X5 are hereafter used because of their generally
observable relationship to the quality of the waters assayed.
COMPARISON OF GROWTH RESPONSE:
LAKE TAHOE AND CREEK VATERS
The comparative ability of Lake Tahoe water and water from Incline, ₯ard,
Upper Truckee -Trout, and General creeks to stimulate growth of Selenastrum in
flask assays is summarized in Table 5-1 f°r "the period of study 1968 through 1970,
inclusive. To minimize the effect of seasonal variations, change in test alga,
temporal changes in water quality, and other time -related factors, values of algal
growth parameters are computed for four time periods. The term "Near Shore" is used
in the table to identify Lake Tahoe water. As noted in the preceding section jj^
and X5 are used in evaluating the findings .
Bearing in mind that the p^ represents the maximum rate of growth attained
during 5 days of assay and represents percent increase in cell counts per day (i.e.
0.254 day"1 means 2 5. 4$ increase per day) Table 5-1 reveals the following findings:
1. During 1968 when development of land on the Incline Creek watershed was
beginning, Incline and Upper Truckee Trout creeks each averaged
1.6 times the growth stimulating potential of Lake Tahoe water (i.e. Ao8/
.25^ = 1.6). Simultaneously, Ward Creek, which drained relatively undis-
turbed land, was no different than Lake Tahoe in growth potential.
2. During the first 6 months of 1969, Ward Creek continued to parallel Lake
Tahoe, but increased activity on the Incline watershed caused Incline Creek
to be more capable of stimulating algal growth than the more stable Truckee
Trout area. Nevertheless, Truckee Trout continued to exceed LW and Ward
Creek in stimulatory potential.
3. In the latter half of 1970 activity on Ward Creek produced a response
similar to that of Incline Creek. Upper Truckee - Trout Creek continued
greater than Lake Tahoe, although less than the two more disturbed water-
sheds in growth potential.
4. During 1970 the growth rates are computed for the entire year, thus the
early high growth rates apparent in Figure 5-7 are obscured by the lower
rates prevailing in the last 6 months of the year. Nevertheless, Incline
Creek continued to be the most productive, but activity on Ward Creek made
it comparable to Truckee - Trout in growth stimulating ability. General
Creek, which was monitored only for 6 months appears more productive in
terms of j. than indicated in Figure 5-7-
71
-------
5. Almost exactly the same facts revealed "by Pb^ are evident in the cell
counts, X5 . The principal difference is the low value shown for General
Creek in 1970, which is more in line with observations shown in Figure 5-7-
6. Seasonal variation in growth rates readily observed in Figure 5-7
show up in the mean values of growth response when 1968 and early 1969
data are compared.
7- Annual averages of growth rates obscure the seasonal peaks which could,
although in this study they did not, represent an algal bloom of serious
nuisance proportions.
CONCLUSIONS
Results of the assays of surface waters in the Lake Tahoe area, specifically
of the lake and 3 principal streams draining surrounding land areas, support the
following major conclusions.
1. Flask assays are capable of detecting changes in water quality which increase
the eutrophication potential of such water, although no one can interpret
the growth rates attained in such assays in terms of the biomass which
might result in an individual outdoor situation.
2. Cell counts (X5) and growth rate (ft^) correlated well with nutrients
present In creek waters.
3. Waters from undisturbed areas showed best correlation with the more stable
forms of nutrients, possibly because of the predominance of such nutrients
from such areas.
h. Human occupancy under conditions of reasonably well developed land (e.g.
Upper Truckee Trout Creek) shows an appreciable increase in algal growth
stimulating nutrients over that of land under natural conditions.
5- Land undergoing development is especially productive of growth stimulating
nutrients, at least under practices which have prevailed in the Tahoe Basin.
6. Relatively undisturbed land as, for example, Ward Creek in 1968 and
General Creek in 1970, reflect essentially the same growth stimulating
properties as does Lake Tahoe water.
7- The evidence shows that Lake Tahoe water is nitrogen poor and supports
such a small biomass that the results of flask assays are not measurably
in error because of nutrients tied up in biomass.
8. Algal assays measure only the residual ability of a water to stimulate algal
growth, hence could theoretically show no potential at all in a water
visibly covered with an algal bloom. Thus, except in unique cases such as
Lake Tahoe, it is more useful in evaluating waste water discharges than in
assessing the eutrophication of surface waters.
9- The presence of humans and human activity on a watershed definitely
increases the rate of eutrophication of its surface waters.
10. Land management and land use controls are essential to a program designed
to maintain the highest possible water quality in an area.
72
-------
CHAPTER VI
EVALUATION OF EUTROPHICATION POTENTIAL
INTRODUCTION
Findings of the surveys, and of the pond and surface water assays reported
in preceding chapters, reveal significant facts concerning the concentration and
algal growth stimulating effects of nutrients from various possible sources vithin
the Tahoe Basin. They do not, however, give scale to any possible effects in terms
of nutrient enrichment of Lake Tahoe. With sewage and household refuse exported
from the Basin, the remaining sources of nutrients, whether resulting from natural
phenomena or from man's activities, may or may not be of foreseeable significance.
Considering the Lake Tahoe Basin as an ecosystem, the unanswered question
then is: What effects do nutrients imported by man or nature, together with those
released by disturbing the soil mantle, have on the rate of eutrophication of Lake
Tahoe?
To answer such a question adequately is beyond the limits of present
scientific information. It would require both an inventory of all growth stimu-
lating materials entering and leaving the basin, plus a vast refinement of knowledge
of what constitutes a growth stimulant and under what conditions. Moreover, it
would entail more knowledge than man presently posesses concerning the natural
interchange of nutrients between vegetation and the atmosphere, and of the variation
of such interchange with meteorological and climatological conditions. Finally, it
would require a knowledge of the interactions of Lake Tahoe and its environment
which no one presently posesses. Such a scientific effort is presently infeasible
and the time span of such an approach would probably make it irrelevant to the fate
of Lake Tahoe.
A guide to human judgement, if not an answer to the foregoing question,
might result from considering what may go into the lake under some natural equilib-
rium within the Basin, estimating the similar input under the impact of man, and
comparing these two estimates with each other and with the observed nutrient content
of the lake water. It is the purpose of this chapter to present such an analysis
based on data obtained during the period of study (l96?-197l); to evaluate the
limitations of the analysis; and to suggest what further work might be productive
of results translatable into action in time to materially affect the course of
eutrophication of Lake Tahoe.
The Basic Approach
The basic procedure hereinafter developed in some detail involves the
following tasks, although not strictly in the sequence listed:
1. Monitor by chemical analysis the quality of surface water entering Lake
Tahoe via 31 creeks, including the four major creeks discussed in Chapter V.
2. Estimate the nutrient input to Lake Tahoe by this system of streams on the
basis of chemical analyses and the fraction of the annual runoff to the
lake represented by each stream.
3. Estimate the annual input of nutrients to Lake Tahoe via direct precipitation
on the lake water surface.
73
-------
k. Calculate the annual hydrological balance of the lake on the basis of
available inflow, outflow, and evaporation data.
5. Calculate the theoretical nutrient content of Lake Tahoe, on the basis
of observed nutrient concentrations, for various combinations of undis-
turbed and developed land.
6. Compare the observed and calculated concentration of nutrients in Lake
Tahoe water.
7. Outline and discuss the factors relating to eutrophication of Lake Tahoe
which may not be evaluated by the foregoing approach.
8. Present conclusions and recommendations based on interpretation of a
combination of observed data and undocumented possible relationships.
CHEMICAL ANALYSES
Chemical analyses of three major creeks discharging into Lake Tahoe (Ward,
Incline, and Truckee Trout) were made over a three year period (1968-70). The
results, previously discussed in Chapter V, are presented in detail in Table D-3,
Appendix D. These represent the most extensive surface water records made during
the study, except for Lake Tahoe itself. Data on the various forms of nitrogen,
P04-P, Total -P. Ca, Cl, pH, alkalinity, and conductivity were obtained at
approximately monthly intervals beginning in 1969, although some similar data were
obtained in 1967-68. During the year 1970 the sampling frequency was increased
to approximately bimonthly. Results reported in Table D-3 for the foregoing water
quality factors were obtained from filtered water samples. Beginning in August
1969 the scope of analysis was expanded to include total suspended solids, volatile
suspended solids, and COD of unfiltered samples of water from the three major creeks
As noted in Chapter V, General Creek was added to the list of major creeks in
July of1970- For purposes of later calculations pertinent to an evaluation of the
eutrophication potential of Lake Tahoe, the most important data on ₯ard, Incline,
and Truckee Trout creeks are summarized in Table 6-1. Summary data of the same
type for mid- and near-shore Lake Tahoe are summarized in Table 6-2 from more
detailed analytical results reported in Table D-l, Appendix D. Chemical and related
analyses for 31 creeks for the period November 1969 to February 1971 are presented
in detail in Table E-1, Appendix E. Records for some of these streams are discon-
tinuous be cause some cease to flow in dry weather and others are inaccessible when
snow is deep- Data on temperature and dissolved oxygen are included for some
sampling dates. For all creeks the data on nitrogen and phosphorus concentration
and .for pH and conductivity are more continuous than for solids and chloride con-
centration. Averages for all 31 streams are included in Table E-2, Appendix E,
along with other information discussed in a subsequent section.
Table E-3, Appendix E, presents the results of chemical analyses of precipi-
tation, mostly in the form of snow, made during the winter of 1969-70 and 1970-71.
Of particular significance to the eutrophication of Lake Tahoe is the high content
of ammonia and organic nitrogen precipitated during the winter season. Average
values of nutrients reported in Table E-3 are compared with those of other sources
in Table 6-3, based on data from Tables 6-1, 6-2, E-2, and E-J. From an inspection
of the table it is evident that:
1. The average of all 31 creeks differs very little from that of the three
major creeks (included in the 31) except in the forms of nitrogen which
make up Total - N. In general,there was more organic nitrogen and less
ammonia in the over all composite than in the three-creek composite.
2. Total nitrogen in the creeks averaged about 2 times that in Lake Tahoe,
whereas phosphorus in the creeks averaged about 3 times as great.
-------
TABLE 6-1
ANALYSES OF SELECTED CONSTITUENTS FROM CREEKS REPRESENTING SUB-DRAINAGE
BASINS IN DIFFERENT STAGES OF LAND DEVELOPMENT81
Creek
Ward
Incline
Truckee -Trout
Composite Avg .
Year
1968
1969
1970
Average
1968
1969
1970
Average
1968
1959
1970
Average
Nitrogen as N
Organic
Mg/^
171
84
89
99
19*1
205
196
199
290
216
184
207
169
NH3
Mg/^
58
21
4i
38
78
127
70
87
118
47
50
58
62
N02 + N03
M8/-0
2k
21
Ik
17
40
114
31
54
65
57
4i
48
4l
Total
ne/-«
253
127
144
154
312
446
297
34o
473
320
275
314
272
Phosphorus as P
P04
MS/^
13
9
12
11
16
26
16
18
15
9
7
8
13
Total
«?A
38
14
24
23
62
4i
35
4o
30
29
16
21
29
Cl
V&I&
0.73
0-55
0.36
0.46
1.50
1.60
1.06
1.05
2.50
2.70
2.48
2.54
1-34
Cond
(io-6)
mhos
58
49
62
58
58
55
6l
59
54
48
57
54
57
aFiltered Samples
-------
TABLE 6-2
AMLYSES OF SELECTED CONSTITUENTS FROM MID AID NEAR -SHORE LAKE TAHOE WATER
CTs
Sample
Mid
Near -Shore
Composite
Year
1968
1969
1970
Average
1968
1969
1970
Average
1968
1969
1970
Average
Nitrogen as N.
Organic
»&/*
118
69
79
83
151
107
95
105
133
89
90
97
NH
3
Mg/ ' &
4l
19
49
36
33
24
35
31
37
21
39
34
w^ + m3
wl*>
1+
9
9
8
4
12
8
9
4
11
9
9
Total
JJg/^
163
97
138
127
188
145
138
145
174
121
138
140
Phosphorus as P,
P04
Mg/^
1
6
3
^
1
4
3
3
1
5
3
3
Total
^g/^
6
9
8
8
4
9
10
9
5
9
9
8
Cl
mg/i
1.4
1-5
1.1
1-3
1-5
1.8
1-5
1-3
1.6
1.3
1.4
Cond
(10- )
mhos
83
79
90
84
83
8l
91
86
83
80
91
86
a Filtered Samples
-------
3. The concentration of Total nitrogen in melted snow was more than 2.5 times
as great as in Lake Tahoe Water, while total phosphorus in the creeks
averaged about double that in the lake.
TABLE 6-3
COMPARISON OF AvERACS VALUES OF SELECTED CHEMICAL CONSTITUENTS 1968-1971
Source
Lake Tahoe
3 Creeks
(Table 6-1)
31 Creeks
(Table E-2)
Precipit .
(Snov)
Nitrogen as N
Organic
97
169
184
191
NH3
34
62
48
117
N02 + N03
9
4i
4i
56
Total
i4o
272
273
357
Phosphorus asP
P04
3
13
10
9+
Total
8
29
22
15-
Cl
1.4
1.34
l.l
1.43
Cond.
86
57
50
10
It is particularly noteworthy that the precipitation reported in Table E-3
(Appendix E) was richer in nutrients than is Lake Tahoe itself. The same was true
for the influent streams. At simple face value this would mean that if Lake Tahoe
could be quickly drained and refilled with surface waters such as observed during
the 1967-71 period, or with snowmelt such as observed in 1970 and 197l> it would
be appreciably more eutrophic than it is at present. Obviously, in the 600 to 700
years it would take to re-establish the Lake, a lot of conditions would change.
But the quality of the Lake Water today suggests either that a lot of things have
been different in the past or that the lake has a capacity to dispose of nutrient
inputs which are not reflected in simple chemical analyses.
An inadequately answered question is the growth stimulating ability of melted
snow. Unfortunately the data reported in Table E-3 (Appendix E) were obtained for
the purpose of evaluating the nutrient inputs to the lake and no flask assays were
made. However, results reported in Tables 3-1 and 3-3 of Chapter III, and in the
several figures of Chapter V, reveal an increasing growth rate in waters which
corresponds to the pattern of increasing Total nitrogen content. It can therefore
be presumed, although not documented, that the snowfall summarized in Table 6-3
would be more stimulatory to algal growth in flask assays than either the creek or
Lake Tahoe waters.
In Table 3-3 of Chapter III, a flask assay of a single January snow showed
it to be similar to Lake Tahoe water in growth stimulating properties, whereas a
single rainstorm, in August produced a much greater stimulatory response. To
present the data in which the observations are based,Table 6-4 is compiled from
1967 and 1968 records and limited data selected from Table E-3 on the basis of
corresponding seasonal dates of snowfall and maximum values.
The data in Table 6-4 generally follow a logical pattern, but suggest a need
for more extensive meteorological observations at the time of precipitation in
order to estimate the probable variation from mean values of nutrient content.
77
-------
For exarnpie; the rainstorm of 8/24/67 was accompanied by lightning. Thunderstorms
are not uncommon in February in the Sierra Nevada mountains. The high M3-N content
of snow on 2/l8/7l in comparison with the January 1970 snows suggests that lightn-
ing may have accompanied the February storm, although no record was kept. In any
event it seems clearly demonstrated that precipitation of any type is normally
richer in nitrogen than is Lake Tahoe.
TABLE 6-4
COMPARISON OF .SELECTED DATA ON PRECIPITATION
Date
8/24/67
11/4/70
1/30/68
1/20/70
1/24/70
2/18/71
Type of
Sample
Rain
Rain +
Snow
Snow
Snow
Snow
Snow
Nitrogen as N (|jg/^)
Organic
450
159
80
252
264
92
NH3
390
212
150
90
115
479
NO 2 + NO 3
200
157
55
24
29
220
Total In.
590
369
205
114
144
699
Total -N
1040
528
285
366
408
791
Phos.(Mg/^)
P04
1
15
c
9
7
9
Total
40
20
c
11
25
17
Wo
0.78a
b
0.27a
b
b
b
50 percent concentration in Lake Tahoe Water (LTW)
(Comparative growth rate in LTW = 0.29 day ~1)-
No flask assay of growth response ma.de.
Data on phosphates inaccurate due to contaminated glassware.
HYDRO LOGIC AND NUTRIENT BUDGETS
Hydrological Factors
The basis of both a hydrologic budget and a nutrient budget in the Lake
Tahoe Basin depends upon the quantity and distribution of precipitation in the
Basin and on its runoff to the Lake. Information on precipitation was obtained by
use of the isohyetal map, Figure 6-1, presented in a 1969 Report of the U. S.
Geological Survey (22). Admittedly a highly refined isohyetal map of the Tahoe
Basin is not possible to construct at the present time because of the limited
number of gaging stations in the area and the abrupt changes in elevation which
affect the intensity of local precipitation. However, for purposes of the study
herein presented, Figure 6-1 is assumed to be the best available estimate of
precipitation distribution at Lake Tahoe.
To estimate the rainfalls and ultimately the runoff and nutrient contribution
of each surface stream, the entire Lake Tahoe Basin was divided into 6l subdrainage
basins as shown in Figure 6-2. Thus it corresponds to a 63 sub-basin map
prepared in 1963 (23) and widely used by many agencies, except that two of the
original boundary lines were eliminated for reasons of evident similarity of adjacent
areas.
78
-------
35
30
N
Isohyetol Line
Basin Boundary
40
FIGURE 6-1. MEAN ANNUAL PRECIPITATION IN THE
TAHOE BASIN
79
-------
rn"L-ir* Limits of Tahoe Basin Study Area
"~ Limits of Intermediate Drainage Areas
63 Number of Intermediate Drainage Areas
SCALE'I". 10,000'
CO
O
McKinney
Bay
45 -W Richardson
Taho*
Keys
Sooth
I Lake Tahoe
Zephyr
\Cove
L ake Tahoe
Glenbrook Glenbrook
Bay
Tahoe
City
Cornelian
Bay
Kings
Beach/
Crystal
Bay
Incline / 16 / 17
Village
16
FIGURE 6-2. DRAINAGE AREAS WITHIN THE TAHOE BASIN
-------
The geographic relationship of the several subbasins are shown graphically
in Figure 6-2., prepared from a similar large scale map in the 1965 Report (23)-
Because of limited scale problems the names of creeks as areas draining the 6j
subbasins are omitted from Figure 6-2. They are, however, identified by both map
reference number and current title in Table 6-6, and Table E-2 (Appendix E).
Elimination of two boundary lines, as previously noted, resulted in including area
No- 27 in area No. 25, and No. 51 in No. 50.
Estimating Precipitation. To estimate the annual precipitation on each of
the 6l sub-basins, use was made of Figure 6-1 and precipitation data from three
weather Bureau stations in the Tahoe Basin as reported in Table 6-5 for the water
years 1960 through 1969- These three stations Tahoe City and Meyers, California
and Glenbrook, Nevada - are located on a triangular grid pattern within the Tahoe
Basin.
In Table 6-5 a percentage of the yearly precipitation for the three stations
is ascribed to each station for each year of record. The cumulative 9-year mean
percentage for each station is also shown. From the results it is apparent that in
terms of percentage of annual precipitation there is little variation from year to
year at any one station. Over the nine year period Tahoe City averaged 56.5$,
Meyers 42.8$, and Glenbrook 20.7% of the average yearly total. From these two
observations it was concluded that any one of the three stations could be used as
a reference to adjust the quantity of precipitation on the isohyetal map (Figure 6-1).
Tahoe City was selected as the reference station both because it was intermediate
between the other two and had a precipitation record that extended over a 60-year
period.
The isohyetal map (Figure 6-l) which, as previously noted, represents the
best available estimate of the long term average in the Lake Tahoe Basin. It shows
that the long-term average at Tahoe City is approximately 30 inches per year.
Assuming 30 inches at Tahoe City as a base line value an annual precipitation factor
was calculated for each of the water years (1961 to 1970) in Table 6-5- The results
showed that the annual precipitation for these 10 years varied from the isohyetal
map (Figure 6-l) average by factors ranging from 0.79 in 1965-66, to 1-75 in 1968-69.
On a ten-year basis it is estimated (Table 6-5) that during the past 10 years the
rainfall has averaged 120$ of the long term average represented by the isohyetal
map (Figure 6-1)
From the foregoing analysis it was concluded that the annual rainfall on
each of the 6l sub-basins might reasonably be calculated from the isohyetal map
using JO inches at Tahoe City as the reference value. Annual precipitation values
estimated for each of the 6l sub-basins are shown in Column h of Table 6-6. The
overall basin average was approximately 33 Inches; ho inches per year for land areas
and 22 inches per year on the lake surface.
Estimating Runoff. To estimate the runoff from each of the 6l sub-basins
the area of each sub-basin was planimetered from 15-minute quadrangle sheets obtained
from the U. S. Geological Survey. The results, reported in Column 3 of Table 6-6
total to within but a few hundred acres of the generally reported totals for the
Lake Tahoe Basin and are therefore adequately accurate for the approach used in the
study.
From rainfall and areal estimates, precipitation was converted to acre-
feet on each sub-basin.
81
-------
TABLE 6-5
REPRESENTATIVE TAHOE BASIN WEATHER BUREAU STATIONS
Station
Tahoe City,
Calif. a
Meyers Station,
Calif. °
Glenbrook,
Nevada0
Total
Yearly
Precipitation
ratio at
Tahoe City
based on an
assumed an ual
average of
30 in.
Water Year
60-61
in.
*»
26.85
1,57
65.83
*
37.1
1(0.8
22.1
100.0
0.81
61-62
in.
30. oU
36.33
1,56
80.93
*
37.1
».,
18.0
100.0
1.00
62-63
in.
1(5.71
53.28
20.76
119.75
*
38.2
It it. 5
17.3
100.0
1.52
63-6i(
in.
25.26
30.26
1,,
70.1(6
*
35.8
43.0
21.2
100.0
0.84
61*-65
in.
51.18
60.30
26.11
137,59
*
37.2
1(3.8
19.0
100.0
1.71
65-66
in.
23.7l(
27.1(1
1,1(7
65.62
%
36.2
1(1.8
22.0
100.0
0.79
66-67
in.
1A.88
55.02
31.82
131.72
i
3,1
41.8
2,1
100.0
1.50
67-68
in.
2,57
30.1(6
16.08
71.11
%
3,6
,,,
22.6
100.0
0.82
68-69
in.
52.59
57.85
V.62
il(0.2b
%
,1.2
.'1 . 3
100.0
-(.75
by-70
in.
-
-
3b . b6
*
-
-
,.:..-
Overall
1900-11 yrj-/
in .
"(1.97
20.35
*.*
*
,,,8
20.7
LOO . 0
a.,' i
(10 yr uvg)
CO
ro
alndex station no. 8758-03, Placer County; elev. 6230; lat. 39"-10'; long. 120'-08'.
blndex station no. 5572-03, El Dorado County; elev. 631(2: lat 38"-51'; long. 120°-01'.
clndex station no. 3205-01, Douglas County; elev. 61(00; lat. 39°-05'; long. lly°-56'.
-------
To establish rainfall-runoff coefficients for each of the 6l sub-basins
an analysis vas first made of six major streams in the basin on which the U. S.
Geological Survey (22, 2.k] operates continuous flow recorders. Of these a 12-year
runoff record is available for Blackwood Creek, Trout Creek, and the Upper Truckee
River. Taylor Creek has been gaged for two years; and Incline Creek and Third
Creek for one year.
A record of the monthly flow data for each of the six streams is summarized
in Table E-^, Appendix E. The percentage of the yearly flow which occurs each
month is also shown in the table in order to make possible a nutrient inventory
based on monthly flows and monthly chemical analyses. Such percentages are also
shown graphically in Figure 6-3- From this figure it is apparent that in spite of
the difference in length of record for the various streams the composite percentage
of annual flow occurring each month differs little from one stream to another.
This uniformity of pattern, coupled with the uniformity of precipitation distrubution
previously discussed, indicates that the hydrological relationships are relatively
uniform throughout the Basin.
Calculated Rainfall-Runoff Coefficients for the six streams cited are
reported in Table E-5- Because flow gaging stations on the Upper Truckee River and
in Trout and Taylor creeks are located some distance upstream from the lake only
the actual drainage area above the gaging station was used in calculating the value
used in the table.
Rainfall-Runoff relationships for the 6 streams subject to continuous gaging
records for various periods are plotted in Figure 6-U. It is noteworthy that the
three streams having the longest period of observation (Truckee, Trout, and Black-
wood) showed a strictly straight line relationship. Even those of short period of
record deviate but little from this line. Obviously the curve would be expected to
drop off as the runoff approaches zero, as it is extremely unlikely that the annual
rainfall which produces no runoff is as great as 20 inches.
Because of the straight line relationship of Figure 6-k-,the figure was
used to estimate runoff in inches depth on the drainage area for each of the 6l
sub-basins in Table 6-6 on the basis of rainfall values previously entered in
Column k of that table. The results of this interpolation are reported in Column 6
of Table 6-6. Thus the runoff coefficient and the runoff in acre-feet for each
sub-basin are readily computed, leading to an estimate of 310,000 acre-feet as the
average annaul input to Lake Tahoe when precipitation at Tahoe City is 30 inches
per year. In making this estimate, runoff values were rounded off to the nearest
100 acre-feet.
Hydrologic Inventory. The data developed in the preparation of Table 6-6
provide much of the information needed to develop a hydrologic inventory. The
components of such an inventory may be expressed symbolically by Equation 6-1.
A S = PL + R.O. E D (6-1)
in which:
AS = Change in the volume of Lake Tahoe
PL = Precipitation falling directly on Lake Tahoe
R.O. = Runoff directly into Lake Tahoe
E = Evaporation from the surface of Lake Tahoe
D = Discharges directly from Lake Tahoe, or from the Lake Tahoe Basin.
All values involved in Equation 6-1 have already been developed in the
preceding pages or can be obtained from records, with the exception of evaporation.
Therefore the equation may be rearranged as follows:
E = PL + R.O. AS D (6-2)
83
-------
TABLE 6-6
ESTIMATED RUNOFF IN TAHOE BASIN
Co
-pr
No.
1
2
3
4
5
6
7
8
9
10
ll
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Sub -Basin
Name
Tahoe State Park
Burton Ck.
Barton Ck.
Lake Forest Ck.
Dollar Ck.
Cedar Flats
Watson
Carnelian Bay Ck.
Carnellan Canyon
Tahoe Vista
Griff Ck.
Kings Beach
East State Line Pt.
First Ck.
Second Ck.
Unnamed Ck. No. 1
Rose Knob (Wood) Ck.
Third
Incline Ck.
Mill Ck.
Tunnel Ck.
Unnamed Creek No. 2
Sand Harbor
Marlette Ck.
Secret Harbor Ck.
Bliss Ck.
Deadman Point
Slaughter House
Glenbrook Ck.
North Logan House
Ck.
Area
acres
977
3; 333
1,002
664
1,042
1,195
1,619
937
2,272
3,540
2,864
1,015
666
1,079
1,127
660
1,388
3,972
4,358
1,457
996
672
1,351
3,094
5,852
616
679
3,530
1,052
Precipitation
in.
34
37
36
30
34
36
38
38
38
36
4o
33
34
39
38
33
40
4l
35
37
38
4o
38
38
31
24
16
ac-ft
2,800
10,300
3,000
1,700
3,000
3,600
5,100
3,000
7,200
10,600
9,500
2,800
1,900
3,500
3,600
1,800
4,600
13,500
12,700
4,500
3,200
2,200
4,300
9,800
15,100
1,200
900
in.
11
13
13
8
11
13
14
14
14
13
16
10
11
15
14
10
16
17
12
13
14
16
14
14
8
2
0
Runoff
Coef .
0.32
0.35
0.36
0.27
0.32
0.36
0.37
0.37
0.37
0.36
0.4o
0.30
0.32
0.39
0.37
0.30
0.4o
0.4i
0.34
0.35
0.37
0.4o
0.37
0.37
0.26
0.83
-
(Included with Sub -Basin No. 25)
27
24
7,900
2,100
5
2
0.19
0.83
ac-ft
900
3,600
1,100
400
1,000
1,300
1,900
1,100
2,700
3,800
3,800
800
600
1,300
1,300
500
1,900
5,600
4,400
1,600
1, 200
900
1,600
3,600
3,900
100
100
1,500
200
-------
Co
vn
31
32
33
34
35
36
37
38
39
4o
4i
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
6l
62
63
Logan House Ck.
Cave Rock
Line Ion Ck.
Sky land
North Zephyr Ck.
Zephyr Cr.
South Zephyr Ck.
McFaul
Burke
Edgewood Ck.
Bijou Park
Bijou
Trout Ck.
Upper Truckee River
Camp Richardson
Taylor Ck.
Tallac
Cascade
Eagle Creek
Bliss State Park
Rubicon Ck.
Paradise Flat
Lonely Gulch Ck.
Sierra Ck.
Meek's Ck.
General Ck.
McKinney Ck.
Quail Ck.
Homewood Ck .
Madden Ck.
Eagle Rock
Blackwood Ck.
Ward Ck.
666,300 ^
202,014
1,401
903
1,811
573
1,712
94o
430
2,502
3,405
3,660
2,490
1,602
2b,4o6
37,325
1,625
12,133
2,698
3,104
5^702
2,583
728
735
74l
5,540
5,690
3,592
735
747
1,394
398
7,551
8,149
202,014
29
22
28
20
30
31
22
30
29
33
29
27
33
48
30
60
49
56
6l
39
3,400
1,700
4,200
9,500
4,300
2,400
7,900
6,300
8,200
10,100
6,000
3,600
7,300
149, 300
4,100
60,700
11, 000
14,500
29,000
8,400
7
1
6
0
8
8
1
8
7
10
7
5
10
23
8
33
24
30
35
15
0.24
0.45
0.21
-
0.27
0.26
0.45
0.27
0.24
0.30
0.24
0.19
0.30
0.48
0.27
0.55
0.49
0.54
0.57
0.38
(Included with Sub-Basin No. 50)
40
46
43
55
42
62
53
57
*4-S
4-S
64
52
2,400
2,800
2,700
25,400
19, 900
18,500
3,200
3,500
5,200
1,500
39,600
35,300
666,300
16
21
19
29
18
35
27
31
21
21
37
27
0.40
0.46
0.44
0.53
0.43
0.56
0.51
0.54
0.47
0.47
0.58
0.52
800
100
900
100
1,100
600
100
1,700
2,000
3,000
1,500
700
22,000
71,500
1,100
33,400
5,400
7,800
17,000
3, 200
1,000
1,300
1,200
13,400
8,500
10,500
1,700
1,900
2,400
700
23,300
18,300
310,900
).6 in0 on land portion in the Tahoe Basin
-------
Co
ON
35
30
< 25
UJ
UJ
O
£C
UJ
20
15
10
UJ
1 5
UJ
O BLACKWOOD
D TROUT
O UPPER TRUCKEE
X TAYLOR
A INCLINE
O THIRD
OCT NOV DEC JAN FEB MAR APR
WATER YEAR
MAY JUNE JULY AUG SEPT
FIGURE 6-3. AVERAGE MONTHLY FLOW PERCENTAGES FROM CONTINUOUSLY GAGED STREAMS
IN THE TAHOE BASIN
-------
70
60
50
d 40
Q.
LJ 30
o:
Q.
20
10
O Upper Truckee
n Trout
O Blackwood
Taylor
Incline
X
A
O Third
10 20
RUNOFF, In.
30
40
FIGURE 6-4. CALCULATED PRECIPITATION VS MEASURED
RUNOFF IN THE TAHOE BASIN
87
-------
Estimation of evaporation by Equation 6-2, of course has the effect of
lumping water loss by evaporation and all errors in the budget into a single term-
Therefore it is important to make use of such information as is available in the
Tahoe Basin as a guide to judgement. Evaporation rates are normally measured at
the Tahoe City weather station during the summer months but the year-round loss of
water by this route is unknown. In 1963 (23) it was postulated that the annual
evaporation loss from the surface of Lake Tahoe was_ kO inches. Some additional
evaporation pans were operated in the Basin during the 1962 water year which seemed
to confirm this value- Significantly, the precipitation at Tahoe City that year
approximately equaled the long term average of 30 inches.
Results of applying Equation 6-2 to data for the water years 1961 through
1970 are tabulated in Table 6-7- From the results shown for 1961-62 (M+l, 330
acre-feet evaporation on the 192 sq mi of lake surface) the computed value of
evaporation is about kj inches, which gives some confidence in the reasonableness
of the equation.
In constructing Table 6-7, precipitation (Column 2) was computed from the
isohyetal map (Figure 6-l) adjusted each year by the precipitation ratio shown in
Table 6-5- Surface runoff (Column 3) was derived from the product of the precipi
tation ratios of Table 6-5 and the total (310,000) of the final column of Table 6-6.
Lake storage in acre-feet was obtained from the U. S. G. S. records, as were values
of discharge to the Truckee River (Cols, k and 5, Table 6-7)- Exported sewage
effluent data were obtained from the records of the South "Tahoe Public Utility
District and the Round Hill General Improvement District. Included in the sewage
export values also is effluent pumped to a cinder cone area by the Tahoe City P.U.D.
Approximately one-third of the cone area lies within the Tahoe Basin and the ultimate
fate of sewage discharged to the cone is unknown. However, for the purpose of the
study herein reported It is assumed to be exported from the Basin. Miscellaneous
discharges (Column 7) include three water rights under which water is diverted into
Nevada from Marlette Lake and Third Creek, and into California from Echo Lake.
Figure 6-5 summarizes in graphical form the hydrologic inventory of the
Lake Tahoe Basin based on average values reported in Table 6-7-
Nutrient Inventory
The quality and quantity of streams discharging into Lake Tahoe are tabu-
lated in Table E-2, Appendix E. The table is a composite of the runoff from each
of the 6l sub-basins and the quality values obtained by laboratory analyis of 31
streams summarized in Table E-l (Appendix E). About 89 percent of the runoff from
the land into Lake Tahoe is carried by these 31 streams. Thus the percentage of
error in any nutrient inventory resulting from failure to monitor flow from the
remaining 30 sub-basins is minima..!. Many of these sub basins, as noted in a previous
section were either seasonal in their discharge or essentially inaccessible during
part of the winter season. To estimate their contribution of nutrients to Lake
Tahoe values were interpolated between monitored sub-basins or, In a few instances,
estimated on the basis of analyses from other areas apparently similar in cover
and land development.
Referring back to Figure 6-3 it may be seen that about two-thirds of the
total flow of the year occurs in the months of April, May, and June. Therefore if
several years of analytical data were available it would be more accurate to use
an average weighted in proportion to monthly flow, rather than simple mean values,
In making a nutrient inventory. However, because data on 28 of the 31 streams
monitored covered only a period of 15 months (Nov. 1969 to Feb. 1971) average
values for the period of observation were used.
-------
00
VQ
TABLE 6-7
LAKE TAHOE BASIN HYDROLOGIC INVENTORY
Water
Year
1960-1961
1961-1962
1962-1963
1963-1964
1964-1965
1965-1966
1966-1967
1967-1968
1968-1969
1969-1970
10 yr Total
Average
Precipitation
Directly on
Lake Tahoe
ac-ft
184,300
227, 500
345,800
191, 100
389,000
179,700
341,300
186,600
398,100
277,600
2,721,000
272,100
Surface Runoff
into
Lake Tahoe
ac-ft
251,800
310, 900
472,600
26l, 200
531,600
245,600
466,400
254,900
544,100
379,300
3,718,300
371,840
A
Lake
Storage
ac-ft
- 177,4-10
+ 46,150
+ 317,660
- 120,700
+ 376,500
- 246,100
+ 211,700
- 99,300
+ 55,200
- 4o,500
+ 323,200
+ 32,320
Discharges
Lower
Truckee
River
ac-ft
83,140
45,920
24,010
98,190
85,250
208,800
227,400
143,120
443, 200
316,600
1,675,630
167, 563
Sewage
Effluent
ac-ft
-
-
-
-
-
-
-
1,200
2,800
3,800
7,800
Miscellaneous
ac-ft
5,000
5,000
5,000
5,000
5,000
5,000
5,000
5,000
5,000
5,000
50,000
5,000
Evaporation
from
Lake Surface
ac-ft
525,370
441,330
471,730
469,810
453,850
457,600
363,600
391,480
436,000
372,000
4,382,770
438, 277
-------
\JD
O
Precipitation on Lake Surface
272, 100 ac ft
Influent Streams
371, 840 ac ft
Evaporation
438, 277 ac ft
Lake Tahoe
Volume 123, 000, 000 ac ft
Storage 720, 000 ac ft
A Storage
+ 32, 320 ac ft
Discharges
173, 343 ac ft
FIGURE 6-5. AVERAGE ANNUAL HYDROLOGIC INVENTORY OF THE LAKE
TAHOE BASIN FOR THE WATER YEARS 1961 THROUGH 1970
-------
The value for conductivity was converted to grams "by the ''rule of thumb"
that 1.0 x 10"6 mhos equal 0-7 mg/^ of total dissolved solids. Thus, conductivity
expressed in grams is a rough measure of the quantity of total dissolved solids.
The nutrient inventory in the basin can be described by Equation 6-J.
A n = I 0 A S (6-3)
in which:
An = Change in the analyzed constituent
I = Input of the constituent
0 = Output of the constituent
AS = Amount of the constituent that is increased or decreased by storage .
Equation 6-J could be expressed in a more convenient form, using the same nomen-
clature as developed in the hydrologic Equation 6-1, i.e.
An = PL + R.O. - D AS (6-4)
Applying this equation to hydrological and chemical data previously presented a
series of tables similar to Table 6-7 were developed for organic - N, HH3-N,
(N02 + N03)-N, Total -N, P04, Total -P, chlorides and conductivity. However,
because only a single average value for each of these constituents was available
no accuracy resulted from applying it to each year separately prior to averaging
the results. Instead average values of precipitation, runoff, lake storage, and
lake discharge were computed and averaged prior to computing the Input, Output,
and other values summarized in Table 6-8.
In Table 6-3 the "Input'1 of any constituent is the average value of that
constituent (e.g. organic nitrogen) reported in Table E-3 multiplied by the 10-
year average precipitation in acre-feet on the lake surface (Table 6-7)- Similarly,
the surface runoff input was derived from Table 6-7 and Table E-2 (Appendix E)-
Values in the Output Column were obtained from an average of the summation of dis-
charges in Table 6-7 multiplied by the concentration of the appropriate constituent
reported for the Truckee River in Table E-1 (Appendix E). For "storage" the cons-
tituent concentration came from the "composite" average in Table 6-2 times the lake
storage (averaged) from Table 6-7-
The final column An, of Table 6-8 represents the calculated difference
between inputs, outputs, and change in storage, expressed by Equation 6-4. A
positive (+) value indicates that there was a greater input than output. Conversely,
a negative (-) value indicates that there was a net loss in the specific constituent
as a result of discharge, dilution, sedimentation, utilization, etc.
EVALUATION OF RESULTS
Comparison of Nutrient Concentrations
For the purpose of evaluation of results Table 6-9 is presented. Although
it concerns only the nutrients which are soluble in water it does reveal a number
of factors specifically pertinent to Lake Tahoe. For example:
1. Precipitation directly on the lake surface, plus runoff from land surface,
has averaged about 644,000 acre-feet per year (over a 10-year period)
carrying nutrients at a concentration approximately twice as great as that
observed in Lake Tahoe during the period of study- Because the lake contains
about 122 million acre-feet of water, the inflow of surface and precipitation
is in the ratio of 1/190. The effect of a nutrient ratio of 2/1 is at
best difficult to evaluate. But the question is raised as to whether the
lake through sedimentation, tieup in biomass, discharge, loss to the atmosphere
-------
TABLE 6-8
ANNUAL MJTRIENT INVENTORY IN THE LAKE TAHOE BASIN3
vo
ro
Constituent
Organic -N
NH3-N
(N02 + W03)-N
Total- N
P04-P
Total- P
Chloride
Conduct i vityb
Input (+)
Precipitation Directly on
Lake Tahoe
ac-ft
272 ,,100
272 , 100
272,100
272 , 100
272,100
272, 100
272,100
272, 100
V-S/&
191
117
56
357
9
15
1A30
4 ,,900
(x 103)
kg
64.il
39-27
18.80
119.82
J.02
5-03
480.00
i64o . oo
Surface Run -off into
Lake Tahoe
ac-ft
371,840
371,840
371,840
371,840
371,840
371,840
371,840
371,840
MS/^
184
48
4l
273
10
22
1,100
35,000
(x 103)
kg
84.39
22.02
l8.8l
125-21
4-59
10.09
505.00
16,000.00
Constituent
Organic -W
NH3-N
(F02 + N03)-N
Total- N
P04-P
Total-P
Chloride
Conduct ivityb
Output ( -)
Discharges0 from the
Lake Tahoe Basin
ac-ft
173,3^3
173,3^3
173,3^3
173,3^3
173,3^3
173,3^3
173,3^3
173,3^3
Mg/-^
158
32
ll
201
6
17
970
39,900
(x 103)
kg
33-78
6.84
2-35
42.98
1.28
3-63
207-00
8530.00
A Storage (+)
Change in Yearly
Lake Tahoe Storage
ac-ft
32,320
32,320
32,320
32,320
32,320
32,320
32,320
32,320
Mg/^
97
3^
9
i4o
3
8
i,4oo
60, 200
(x 103)
kg
+ 3-87
+ 1.36
+ 0.36
+ 5-58
+ 0.12
+ 0.32
+ 56.00
+2,400.00
A n (±)
Constituent
(x 103)
kg
+ 110.85
+ 53-09
+ 34.90
+ 196.47
+ 6.21
+ 11.17
+ 722 . 00
+6,710.00
Average values for the water years 1961 through 1970.
"'-'Based on the assumption that 1.0 micro-mho equals 700
Lower Truckee River, Sewage Treatment Plant Effluents, and Miscellaneous Discharges (Water Rights for
Marlette Lake, Third Creek, and Echo Lake).
-------
TABLE 6-9
COMPARISON OF VARIOUS OBSERVED AND COMPUTED NUTRIENT VALUES
Source
Lake Tahoe
Stream +
Precipitation
Stream +
Precipitation
Ward Creek
Incline
Creek
Truckee
Trout Creek
Secondary
Sewage STPUD
Tertiary
Effluent
STPUD
Precipitation
Measure Evaluated
Mg/^
Kilograms (10 yr.
avg . ) in 644, 000 af
Mg/.0 (from data
Table 6-8)
Mg/,0 (Table 6-l)
pg/,8 (Table 6-l)
IJg/i (Table 6-1)
\igf & (Table C-4,
averaged)
Mg/,0 (Table C-4,
averaged)
Mg/.e (Table 6-3)
Nitrogen as N
Organic
97
147,670
186
99
199
20?
2,170
447
191
NH3
34
61,290
77
38
87
58
2i;445
14,695
117
N02 + N03
9
35,590
45
17
54
48
3,000
461
56
Total
140
245,030
308
154
34o
314
26,630
15,920
357
Phos . as P
P04
3
7,600
10
11
18
8
9,330
147
9+
Total
8
15,140
19
23
40
21
9,734
172
15-
Cl
i,4oo
984,510
1,240
460
1050
254o
25,700
26,300
1,430
Cond.
(mg/^)
60.2
17, 700
x 103
2.23
40.5
41-3
37.8
350
385
7
-------
or other complex phenomena manages to purge Itself of the effect of influent
and evaporative factors which tend to increase its nutrient content. If
not, then the proposition must "be entertained that over the past 200 years
the input to the lake has not been as great as estimated for the past 10
years on the basis of short term observations.
When Ward Creek data are compared vith Lake Tahoe data there is a striking
similarity in the nitrogen series,, to which the lake has been shown to be
sensitive. However, as noted in a previous section, an increase in nitrogen
about twofold in value appears when Ward Creek is compared with Incline or
the Upper Truckee - Trout Creek system. Because Ward Creek, until recently,
drained an area not greatly disturbed by man, and the other two creeks
reflect human activity, it is concluded herein that the "stream and
precipitation" data in Table 6-8 reflect an influence of relatively recent
origin which involves a nutrient enrichment of Lake Tahoe .
The relative contribution of precipitation and surface streams to such
an enrichment is not possible to isolate. Both are of about the same
magnitude and bear about the same relationship to Lake Tahoe water. It is
easy to assume that because precipitation is a natural phenomenon it has
undergone less change in nutrient content than have surface streams draining
land undergoing development by man. However, the growing pollution of
Earth's atmosphere in general, and the specific geographic location of
Lake Tahoe with respect to urban areas and agricultural land along the
route of planetary circulation, make any such assumption a doubtful one-
2. The relative importance of precipitation, surface runoff, and domestic waste
water in the Lake Tahoe Basin can be estimated from the Total nitrogen values
presented in Table 6-9- For example, secondary sewage effluent used in the
Pond Assays (Chapter V) averaged about 190 times as rich in Total nitrogen
as Lake Tahoe and 87 times as rich as the combined stream and precipitation
inputs. For tertiary effluent the corresponding values were Il4 and 52,
respectively.
In terms of sewage based on 100 gallons per capita per day, the total
nitrogen contributed by 644,000 acre feet of runoff and precipitation is
equivalent to the secondary effluent from about 66,700 people (assuming
26.63 mg/^ represents the concentration of Total N in Secondary sewage);
or about twice the annual resident population of the Tahoe Basin.
Considering only the excess of Total nitrogen over that observed in the
lake (i.e. 168 = 308 l4o, Table 6-9), and ascribing this excess to human activity
on the basis of the similarity of Ward Creek and Lake Tahoe; the 1970 potential
of streams and precipitation to enrich the waters of Lake Tahoe is equal to the
Secondary sewa.ge effluent of some 36,4-00 people about that of the resident popu-
lation of the Basin.
Assuming the 1970 summer population for 3 months to be about 8 times the
year-round population, it can be calculated on the basis of water analysis alone,
that the activities of man in the Tahoe Basin represent at least 30 percent of
the total potential of man to enrich Lake Tahoe with nitrogen. (i.e. If all
human sewage had been exported in 1970 it would have removed 70 percent of the
nitrogen ascribable to human activity within the basin). Of the total nitrogen
discharged to the Lake by man and nature in combination, sewage export of all
sewage might have accounted for only 60 percent of the total. ~
It should be borne in mind that the foregoing analysis is developed to
give some scale to the effects associated with man's occupancy of the basin. It
necessarily assumes that analysis of soluble nutrients in waters measures their
algal growth stimulating potential; that all sewage is exported from the basin;
-------
that precipitation prior to man's occupancy was no richer in nutrients than the
lake water analysis reflects; and a number of other refinements too lengthy to
catalog here. Some of these limitations are discussed in the following section.
However, it seems probable that Table 6-9 suggests that all measures possible
should be taken to limit the influent of nutrients to the Lake, on the basis of
both what we know and what we don't know. Such a conclusion is supported by the
1963 Report (23) in which Dr. Karl Wuhrmann evaluated Lake Tahoe in the light of
his observations there and of his long experience with European lakes. Of Lake
Tahoe he said "...the relationship between nitrogen and phosphorus may be of controlling
importance. It appears that at concentrations of 10 |_tg P/i no blooms would occur
with nitrogen concentrations below about 50 pg/^- Heavy growth is likely, however,
should nitrogen (NH3-N plus (N02 + N03)-N) exceed 100 |og/^ for the same level of
phosphorus." Wuhrmann went on to predict the nitrogen sensitivity of Lake Tahoe
demonstrated in various sections of the study herein reported. On the basis of his
criterion, the "stream and precipitation" input to Lake Tahoe reported in Table 6-9
is capable of supporting growth that the lake itself does not harbor. Such a
potential was further reflected in an analysis (3) by Dr. James B. Lackey of a few
creek discharges at Lake Tahoe in April 1970.
Evaluation of Other Factors
As pointed out in a preceding section, an evaluation of the eutrophication
of surface waters in general requires a great deal more attention to the biota
existing in a water than is readily attainable by laboratory water analyses and
bioassays. In the pilot pond assays herein reported, however, biomass was measur-
able by suspended solids increase because the VSS in Lake Tahoe water was constantly
small and varied throughout the year in no detectable pattern (see Table ^-3)-
This was due in no small part to a lack of the abundance of species of phytoplankton
which characteristically follow each other in a sequence of blooms in eutrophic
waters . In contrast, the dominant organism observed in Lake Tahoe during the study
were attached diatoms, including Synedra and Gomphoneis. Synedra was a particularly
large component of the biomass attained in the pond assays, although a few other
species and a few small flagellates were not uncommon. On occasion very large
mats of Gomphoneis rcse to the surface and drifted ashore at the north end of the
lake. Previous estimates (23) of plankton in the top 100 meters of Lake Tahoe in
1962 included Copepods (1100/m3); Cladocera (500/m3); and Rotifera (10,400/m3) in
samples taken in May. In previous and subsequent months the numbers of such
plankton were drastically reduced.
In April 1970 Dr- James B. Lackey made a short-term field study and a review
of literature related to Lake Tahoe His comments on abatement of eutrophication
of the lake are worthy of reporting here in some detail.
"1. One thing generally not recognized is that even such a lake as Tahoe should
now and then develop algal growths, dense enough to change its turbidity
at least for a while, and probably in the upper 30 or ko feet. This would
possibly be seasonal the heavy precipitation in the basin is from
November to March, and the heaviest run-off would follow a sudden thaw, or
the spring temperature elevation.
This run-off should bring down such nitrate and phosphate as has accumulated
in the litter on the basin floor. There is some indication of this in a
table of the 1963 report (23), for four of the 60 tributary streams, although
the table indicates the largest water inflow to be in May-June-July. At
any rate, no natural lake, even one in which the nutrients are as low as
they are in Lake Tahoe, will fail to have an algal (and other) population
unless toxic materials are present, and any increase of nutrients will
bring an increase in algal cells. So it must be recognized that for ages
Tahoe has each year produced an 'algal crop, probably highest in the spring
or summer when the temperature is most favorable. In the third annual
report (3) the indication is that this high peak is in March.
95
-------
"2. Another point recognized by algologists, but usually not by chemists and
engineers is the extremely small amount of orthophosphate and nitrate
nitrogen needed to support a good-sized crop of plankton algae. In the 1963
report (23) Table 11-XXII certainly shows enough for such support. This
report, and subsequent ones indicate diatoms as being the dominant algae,
and this table also Indicates that silicon is not limiting for the diatoms.
In other words, Tahoe should have at all times a standing crop of plankton
algae and the amounts of nutrients will vary month to month, but sometime
during the year there will be enough buildup to support a several-fold
increase in the standing crop- This statement is borne out, insofar as
algal cells are concerned, by Table 9 in the Third Annual Report (3).
"3. There have been statements in regard to filamentous algae, and also diatoms,
attaching to rocks, expecially in shallow areas such as Tahoe Keys.
Absence of such growths would be most unusual. These growths are a normal
consequence of being close to the interface, where settled out organic
matter is being mineralized. The crux here is whether or not such growths
are excessive. Such growths in many places (Lakes Waubesa, Kegonsa in
Wisconsin, some . oxidation ponds in California, Great South Bay in
New York) entrap gas, rise to the surface, die in the hot sun, and become
real nuisances. If this happens in Tahoe, there is a problem. If it
does not happen, remember that these and other algae, have real functions
such as being part of the food chain, and tying up the soluble nutrients,
then spreading out their recycling over a long period of time.
Quantitating such growths is difficult, but can be and should be done, to
guard against an increase in eutrophication. It must be remembered that
fishing is one part of recreation, that the fish in Tahoe probably are
primarily dependent on insect larvae, which feed on algae of various sorts.
"k. Examination of Lake Tahoe growths was made at only a few places, but growths
were exceedingly sparse. Only one filamentous alga, Ulothrix, was noted
in sparse growth. This I have never seen to attain the tremendous biomass
sometimes reached by such filamentous algae as Spirogyra. No chain diatoms
were seen, and very few single ones. The lists of microorganisms in the
various publications indicate a very sparse plant population and almost no
protozoa. A detailed examination of centrifuged samples, scrapings from
rocks, and sediment-water interface material in the late summer might yield
a higher crop ....
"5- Disturbance of the waterfront was evident at several locations around the
lake, and on some tributary streams. Practices to be strictly limited
include: any drag line operations on the lake front or In tributary waters;
dredging in tributary or lake waters; storm drainage run-off; over fertili
zation of golf courses (a common practice); fertilization of lawns adjacent
to the lake; any use of pesticides; and any admission of water from such
commercial enterprises as laundromats or restaurants.
"6. Since the domestic sewage removal is aMost complete, it would seem that
most caution has to be taken relative to tributary streams. These are
difficult to control as regards to natural run-off, but few seem to originate
from potential sources of trouble. There is no arable or pastured land
drainage, and the soil is largely granitic. Coniferous litter is nutrient
poor, compared to that from deciduous forests. Therefore, the factor to be
watched is use of tributary streams by the human population. This presumably
is being done.
"? One anomaly was seen. The Truckee River, from the time it left the lake,
until we last saw it at Truckee, had a covering of its rocky bed by the
largest and most dense growth of Ulothrix I have ever seen. Obviously
this growth was supported by lake water; it appeared too quickly and too
96
-------
voluminously to be due to ground-water inflow into the river. The lake
evidently has the potential for supporting a heavy algal growth at least
sometimes, and why such growths have not "been reported until now I cannot
explain."
Conclusions to "be drawn from Dr. Lackey's analysis are generally self
evident. However, his final statement supports the initial comment in this section
that field studies of biota are a necessary aspect of an evaluation of eutrophi-
cation. Long term studies of the limnology of Lake Tahoe are needed, and some
have been underway for a number of years. Unfortunately the results have not
been brought together and evaluated in any scientific report and such information
as has appeared in public lectures, scientific papers, and the public press has
not made possible its evaluation in the context of this report. Plans to include
further work by Dr. Lackey and others during the 1970-71 grant period had to be
abandoned for lack of approval of a budgetary request for consultant services.
Consequently, the relationship between water quality and bioassays measurements on
a laboratory and pilot pond scale, and biological findings in the Lake itself
remains inadequately evaluated. Nevertheless, the findings herein presented seem
clear in their indication that man's activities in the Tahoe Basin should be
subject to controls not common in less obviously critical situations.
Other Unevaluated Factors. As environmental concern becomes more widespread
and biologists increasingly turn their attention to environmental study two things,
at least, become increasingly clear:
1. That water quality standards or criteria do not necessarily measure the
quality of life within that water, and
2. That the critical ecological situations in lakes, ponds, and the ocean
occur in the estuaries, bays, and shallow coastal or near-shore waters.
Action related to the first of these two depends upon an understanding
of the second. Lackey in his report (item 5) calls attention to this. Likewise,
the findings of the study herein reported (j) particularly show the dangers of
confining waters along the shoreline for the purpose of attracting and concen-
trating human activity. Thus both the untidiness and the activity of man tends to
enrich the waters in shallow keys and marinas and to add both algal growth and
litter to that portion of the lake most readily observed by the public. It is then
only a matter of extrapolation to assume that the entire Lake has already suffered
the fate which may yet be many years in coming.
Prom observations of this phenomenon it is concluded that land use controls
far more rigid than any yet established in the U. S. are necessary to protect Lake
Tahoe from accelerated eutrophication. In fact, this conclusion applies equally
well to surface waters in general, particularly in regions where animal manures,
agricultural fertilization, and discharge of sewage and industrial effluents con-
tribute nutrients on a scale not approached in the Tahoe Basin.
The second concern for critical areas in Lake Tahoe are its natural
embayments and areas of discharge of surface waters. It is not uncommon, for example,
to see the waters of Emerald Bay covered with pollen. That this represents a rela-
tively insignificant contribution of nutrients to Lake Tahoe has been suggested (25).
More important is the fate and nutrient contribution of sediments deposited at the
point of discharge of streams. Aerial photos have shown the pattern of turbid water
at times of heavy snow melt. As might be expected, deposition is greatest in the
shallows where it is most obvious to the observer and where its effect on increasing
or decreasing biomass is at a maximum. Random analyses of surface runoff from bare
roadside land made during the study showed sediments too high to measure as suspended
solids. The extent, amount, nutrient content, and ecological importance of sediments
is one of the major inadequately evaluated factors at Lake Tahoe. Current studies
of this problem by the U. S. G. S. and others should be expanded and continued.
97
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SECTION IV
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
herein reported.
Technical direction of the study was provided by the LTAC Board of Con-
sultants (P.H. McGauhey, G.A. Rohlich, and E.A. Pearson) as a part of their
commitment to the Lake Tahoe studies and as a donated public service. Experimental
work and data processing activities were led by Dr. Gordon L. Dugan, Project
Engineer-Biologist, and Dr. Don B. Porcella, Project Limnologist. They were assisted
by Messrs. Peter Cowan and Jack Archambault, and by Mrs. Florence Kupka and Mrs.
Nancy Deliantoni in field and laboratory studies and analyses. Special studies
and data evaluations were made by Dr. James B. Lackey, Consulting Biologist,
Melrose, Florida; Dr. Arthur B. Hasler, University of Wisconsin; and Dr. E.J.
Middlebrooks, University of California. Budgetary control and accounting were
maintained by Mrs. Lois Williams and Mrs. Katharine Belyea of the LTAC staff. The
Council acknowledges with thanks the dedicated contribution of these individuals to
the conduct of the study, the work of Messrs. P.H. McGauhey and Gordon L. Dugan in
writing the report, and the assistance of Mr. Peter Bray and Mrs. June Smith in
producing the report manuscript.
Agencies directly cooperating in the study include the California Regional
Water Quality Control Board No. 6 for information and counsel; the California
Department of Fish and Game, which contributed facilities as well as technical
assistance; the South Tahoe Public Utilities District, which provided data and
water samples needed in the investigative work; the California Department of Water
Resources, which provided water quality and stream flow data; the University of
California, which contributed facilities as well as technical assistance; the
U.S. Coast Guard and Placer County, which provided sites and easement for a Lake
water delivery system; Dr. Charles Goldman of the University of California, Davis
for laboratory facilities and staff assistance; and the U.S. Geological Survey,
Carson City, Nevada for providing stream flow and stream sediment data. Agencies
cooperating in the planning and design of the project included, in addition to
the foregoing, the California State Department of Public Health, the Nevada State
Department of Public Health, the Douglas County Department of Health, and the
Placer County Department of Health. The assistance and counsel of these agencies
and their representatives is gratefully acknowledged.
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 Grant Project Officer, and to Mr. William C.
Johnson who represented the Regional Office in advising the project staff.
-------
SECTION V
REFERENCES
1. McGauhey, P. H-, G. A. Rohlich, E. A Pearson, M. Tunzi, A. Adinarayana, and
E . J . Middlebrooks, Eutrophlcation of Surface Waters - Lake Tahoe :
Bioassay of Nutrient Sources, LTAC, FWPCA Progress Report for Grant
No. WPD ^8 -01 (Rl), May 1960.
2. McGauhey, P. H., E. A. Pearson, G. A. Rohlich, D. B. Porcella, A. Adinarayana,
and E. J. Middlebrooks , Eubrophication of Sarface Water - Lake Tahoe :
Laboratory and Pilot Plant Studies, LTAC, FWPCA Second Progress Report
Grant No. WPD ^8 -02, May 1969.
3. McGauhey, P- H.} G- A. Rohlich, E. A. Pearson, G. L- Dugan, D. B- Porcella,
and E . J. Middlebrooks, Eutrophication of Surface Waters Lake Tahoe :
Pilot Pond and Field Studies, LTAC, FWQA Third Progress Report Grant "
No. 16010 DSW, May 1970.
k. McGauhey, P. H., E. A. Pearson, G. A. Rohlich, D. B. Porcella, G. L- Dugan,
and E- J. Middlebrooks, Eutrophication of Surface Waters Lake Tahoe
(Indian Creek Reservoir), LTAC, FWQA First Progress Report Grant No .
16010 DNY, May 1970 .
5- P- H- McGauhey, Engineering Management of Water Quality, McGraw-Hill, 1968.
6. Oswald, W- J-, Fundamental Factors in Stabilization Pond Design, Advances in
Waste ₯ater Treatment, Pergamon Press, New York, 1963
7- Skulberg, 0- M., "Algal Cultures as a Means to Assess the Fertilizing Influence
of Pollution, I, in Advances in Water Pollution Research, p. 11J,
Academic Press, 1965.
8. Michaelis, L. and M. L. Menten. Biochem. A., |j£:333, 1913-
9- Monod, J. "The Growth of Bacterial Culture," Annual Review of Microbiology,
III,
10. Caperon, J. ₯ "The Dynamics of Nitrate Limited Growth of Isochrysis galbana
Populations," Ph.D. Thesis, University of California, San Diego, 1965.
11. Maddux, W. S. "Application of Continuous Culture Methods to the Study of
Phytoplankton Ecology, " Ph.D. Thesis, Princeton University, 1963
12. Williams, F. G. "Population Growth and Regulation in Continuously Cultured
Algae," Ph.D. Thesis, Yale University, 1965.
13. Jannasch, H. W. and R. F. Vaccaro. "Studies on Heterotrophic Activity in
Seawater Based on Glucose Assimilation," Limnol. and Oceanogr . ,
11:596-607, 1966.
14. Dugdale, R. C. "Nutrient Limitation in the Sea; Dynamics Identification and
Significance," Limnol. and Oceanogr., 12_:685, 1967-
15. Pearson, E. A. "Kinetics of Biological Treatment," Proceedings Special Lecture_
' Series - Advances in Water Quality Improvement, University of Texas,
April 1966.
101
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16- Standard Methods for the Examination of Water and Waste Water, 12th Ed.,
American Public Health Association, New York,1965.
17. Strickland, J. D. H. and T. R. Parsons. A Manual of Sea Water Analysis,
Bulletin No. 125, Fisheries Research Board of Canada, Ottawa, 1965.
l8. Jenkins, D. Analytical Methods, Sanitary Engineering Research Laboratory,
Richmond, (mimeographed), 1966.
19- Maciolek, J. A. Limiiological Organic Analyses by Quantitative Bichromate
Oxidation, Bureau of Sport Fisheries and Wildlife, Research Report 60,
Washington, D. C-, 1962.
20. Fend, Z., A uniform system of "basic symbols for continuous cultivation of
micro-organisms, Fol. MicroMol., 8:192, 1963-
21. Whipple, G. C., The Microscopy of Drinking Water, Fourth Edition, John Wiley
and Sons, New York, 1927-
22. Crippen, J. R. and B. R. Pavelka, "The Lake Tahoe Basin, California Nevada
Open-File Report, U. S. G. S. Water Supply Paper No. 1972, Menlo Park,
California, May 2J, 1969.
23. McGauhey, P. H., et. al., "Comprehensive Study on Protection of Water Resources
of Lake Tahoe Basin," Lake Tahoe Area Council, 1963.
2h. "Wat.-.::1 Resources Data for Nevada", U. S. Geological Survey Annual Reports,
1961 1970.
25. Richerson, P. J., G- A. Mashiri, and G. L. Godshalk, "Certain Ecological
Aspects of Pollen Dispersion in Lake Tahoe (California Nevada),"
Limnology and Oceanography 15,1, January 1970-
102
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SECTION VI
APPENDICES
A. Analytical Procedures
Table A-l: Modified Skulberg Nutrient Medium
Table A-2: Analytical Procedures
B. Chemical Analyses on Surface Waters
Table B-l: Chemical Analyses of Various Waters Surveyed in
the Lake Tahoe Area
C. Chemical Analyses of Pilot Pond Waters
Table C-l: Chemical Concentrations in Ponds
Table C-2: Results of Analyses of Pond Input Waters. . . .
Table C-3: Pilot Pond Analyses
Table C-k: Pilot Pond Influent Chemical Analyses
Table C-5: Biomass Measurements
Table C-6: Simulated Secondary Effluent Feed for
Pilot Ponds
D. Bioassays of Lake and Creek Waters
Table D-l: Chemical Analyses of Shore and Mid-Lake Tahoe .
Table D-2: Maximum Growth Rates and Maximum Cell
Concentrations Attained at the End of Five
Days in Flask Culture of Lake Tahoe Water . . .
Table D-3: Creek Water Analyses
Table D-4: Maximum Growth Rates and Maximum Cell
Concentrations, Flask Assay of Creek Waters . .
E. Nutrient Contribution of Surface Waters
Table E-l: Creek Analyses
Table E-2: Nutrient Inventory of Streams Discharging
into Lake Tahoe
Table E-3: Analyses of Precipitation in the Tahoe
Basin
Table E-^: Continuously Recorded Streams in the
^ake Tahoe Basin
Table E-5: Rainfall-Runoff Coefficients for Continuously
Gaged Streams in the Lake Tahoe Basin
Page No.
103
105
106
107
10?
109
109
116
118
130
132
135
137
137
133
139
151
152
153
103
-------
TABLE A-i
MODIFIED SKULBERG- NUTRIENT MEDIUM
H
O
Ul
Macronutrients
NaN03
Ca(N03)2 - ^H20
K2HP04
MgS04 7H20
Na2C03
Fe EDTA (FeS04 + Na2 EDTA)
Final Concentration (mg/0)
k6.7
5-9
3.1
2.5
2.1
0.2 as Fe
Micronutrients ^_
(Adapted from Myers, 1951)
CO(N03)2 6H20
(NH4)6 M07024 ^H20
CuS04 5H20
Zn(C2H302)
MnCl2 4H20
H3B03
Final Concentration (mg/,0)
0.0012
0 . 0122
0.0200
0.0382
0.050
0.50
Myers, J. (1951). "Physiology of the Algae,, Ann. Rev. Microbiology, 6:l65-l80.
-------
TABLE A- 2
ANALYTICAL PROCEDURES
1. pH and alkalinity were determined "by Standard Methods [l6j.
Total alkalinity expressed as mg/l CaC03 was determined by potentiometric titration. The
pH recorded was the initial pH of the water "before the acid was added in the titration.
2. Iron.
The bathophenanthroline method outlined by Strickland and Parsonstl7] was used for
determination of total soluble iron, including ferrous and ferric iron, and complex
ferric and colloidal ferrous forms.
3. BOD[l6].
BOD determinations were performed on unfiltered samples. l£ke Tahoe water was used to
dilute vaste water samples when necessary. Generally no dilution for stream water was
required.
4. COD [16].
COD determinations were performed on unfiltered samples. Because both dilute water
samples and waste water were analyzed, oxidation was accomplished "by using 0.25 N, 0.05 N,
and 0.025 K KaCr^.
5. N03[l7l.
NO} in water was reduced to N02 by passing the sample through a column of cadmium filings.
The NOs was then determined.
6. N02[17].
NOs was determined by colorimetric reaction using sulphanilamj.de and naphthylethylenediamine
solution.
7. NH3 [16],
NH3 was distilled into a boric acid solution and then nesslerized. Equipment used for the
analyses was divided into two sets, one for distillation of sanples with relatively high
concentrations of ammonia and the other for samples with lov levels such as lake and creek
samples.
8. Soluble Organic Nitrogen [l6,17l.
The sample remaining after NH3 distillation (usually about 2^ nj) was digested with a
sulfuric acid-selenium dioxide mijcture. When the digestion VES complete, the residue was
diluted with Nib-free water, made alkaline, and distilled for the NH3 as reported above.
9- Inorganic Phosphorus (Reactive) [17]-
The sample was mixed with a reagent containing sulfuric acid, ainmonium molybdate, and
antimony potassium tartrate, adding afterwards ascorbic acid dissolved in ethyl alcohol.
The blue color was then read directly from a Beckman spectrophotometer in a 1-cm or 5-cm
cell. (The modification used was reported by Richard Armstrong, Institute of Ecology,
University of California, Davis.)
10. Total Inorganic Phosphorus [16].
Total inorganic phosphorus was determined after hydrolysis with a strong solution of
sulfuric and nitric acids. A 100 ml sample with the acid solution was autoclaved, cooled
and then made alkaline. The inorganic phosphorus was then determined as described above.
11. Chlorides [16].
Chlorides were titrated with mercuric nitrate.
12. Calcium [16],
Calcium determinations were made by titration with EDIA (ethylenediaminetetraacetic acid).
13. Conductivity [16].
Specific conductance (|j niho/cm) measurements were done with e conductivity bridge,
Model RC 16B2, made by Industrial Instruments, Inc.
106
-------
TABLE B
CHEMICAL AMALY3ES C" VABIOUS WATEFj 5 .?
Date
19oo
11- 7
11-20
11-20
1907
1- 1
5-20
5-20
5 -20
C- 4
6-17
6-17
6-1-
D-1'5
0-25
6-29
7-17
7-1"
7-15
8- 9
8- 9
3-23
3-24
3-24
8-24
3-24
3-2-
8-2"
3-27
9- 2
9-14
9-15
9-16
9-16
9-16
9-16
9-18
9-18
9-18
9-20
9-22
10- 6
10-16
10-17
10-30
10-30
12-12
12-12
1968
1-20
1-30
2-13
2-13
2-24
3- 1
3- 2
3-11
1*- 2
<*- 5
4-12
Loca ti jn
Storn Drain 3i oul
Storn Drain Sl.'oul
Tahoe Keys
Sr.ov
Mee.^s Cree^
Ward Orees
Incline Oree^
Mil-Use Tahc-e
Meetts Cree-t
Ward Oree*
Ir.cl.ine >-'->-:
Xarir.a Oarnelia:-. 3ay
Incline 27?
Effluent -Incline _: .T
Sewage- Inc I'.r'.e IT?
Ef flue.-.:- Inc line IT7
War! OreeK
Primary Effluent -
NT? 'ID
Secondary Effluent-
STPUD
Mid-Lake T^hoe
Rain
Star- Drain 5i, ^
Spray oeec&Je-Srp'jTI
Hatchery Sva-p
Meeks Tree.-;
War! Tree <
Incline Crse.-;
Pri-iary Effluent -
TCPUD
Secondary Effluent-
Reno -Spares 5T?
Septic Tank Seepage
Rav Sewage -TCF'JD
Pri^ar-y Effluent -
NTPUD
Refuse Dusp itre.!:.!-
Ifpstreaa
Refuse Du.rp Strea-:-
Dovnstream
Stor~ Drain 'Bijou)
Trickling Filter
Effluent-TCPUD
Tahoe Keys
Oxidation Pond [Lav
Rate) -Incline STP
Oxidation Pond (High
Rate) -Incline 3TF
Secondary Effluent-
Reno-Sparks STP
Secondary Ef fluent -
Reno-Spares STP
Spray Seepage -:rT?'j"D
Oxidation Pond-STFJD
Spray Seepage-3TPUD
Secondary Effluent-
Reno-Sparks STP
Incline Creek
Upper Truckee -Trout
Creek
Snov
Primary Effluent-
Reno-Sparks STP
Secondary Effluent-
Reno-Sparks ST?
Upper Truckee -Trout
Creek
Hatchery Swanp
Marina Carnelian Bay
Storm Drain
Septic Tank Seepage
Refuse Dump-
Dovnstream
Rav Savage -TCPUD
'Jnf iltered
3a:^ples
BCD
- 0
~-c
0
- ?
5
5
11,?
7
135
*4
95
0
120
0
0
-
203
1C
150
168
129
i
5
126
17
30
7
14
5
L
2
2
It
1
70
_j^
-0
10
s
s
35
205
*i!t
-
15
10
-
22
10
I;
loO
12
3»
<5
-
10
lo
380
250
8
35
11*8
7
36
520
85
120
430
112
1*
47
45
112
10
52
60
18
10
1*9
78
C.45 u Millipjre Filtered J.-.3:j ^i
Nitrogen as "I
4* (
-"0
110
100
A;
ICO
;50
70
20
oO
v
-o
oC
200
loO
^50
oCO
110
"50
1,500
107
-50
2,COL
-00
2, 30C
lOO
1^0
200
3co
,,200
930
2,1*00
4,000
350
900
2,oOC
1,000
500
9, ceo
9,3cc
350
250
4 CO
I*,OOC
1,700
1,300
200
L2O
80
i,5oc
2,2CC
22O
930
300
250
2, COO
250
2,900
-i\
0
:0
2oC
<5
lo
^0
20
<5
<5
5o
5
<5
7,ooc
2,000
1*0
23,000
18,500
15
390
350
300
2,500
-0
20
90
41,000
9,500
30,000
24,000
31,000
50
110
680
3,800
90
70
350
12,000
3, 1*00
30
1,500
150
25,000
90
200
150
21,500
21,000
70
2'*0
130
160
12,500
145
67,000
-It t
<1
2
s
I
-
5
7
3
i
2
3
1
9
26
15
o2C
3
9
70
1
9
<1
75
j
2-3
4 J7
loo
30
65
113
132
253
-
3,179
2",7;o
1-5
23,760
20,320
125
1,030
3,451
900
4, 9C1
151
305
41, 381
15, 2CC
30,966
26,412
35,021
1*1*8
1,060
3,311
9,816
630
9,083
10, 161
14.20C
11,650
1*53
5,625
1,962
26,1*25
305
1*11*
285
23,02C
23,236
395
1, 191*
i*55
1.97
14,531*
1*52
69,920
.-r.ojtnjruj as P
" *> 4
-t, I
38
130
o
4
<5
<5
j
<5
17
12
20
17
' , -t-OG
I0,3co
5,5co
17, -co
<5
13,500
20,900
3
<1
loO
<5
<5
<5
<5
<5
18,000
5,000
1*2
8,400
6,200
40
77
110
8,800
8
4,500
2,500
13 , ooo
19,500'
30
1,000
100
32,000
30
1*0
35
:c,2cc
;-,4co
50
75
27
3fi
19,400
68
30,600
Total
-s, <
s;8
215
23
12
15
4
1C 4
29
?0
27
-5
23
5,200
2C , 000
o, 100
17,000
103
i7,OOO
27,000
^
1*1
255
103
303
33
28
45
27,500
15,000
302
22,600
23,000
60
88
200
22, 300
16
5,oco
3,000
14,000
20,500
45
2,000
110
32,000
60
80
185
32,900
34,1*03
73
122
55
82
20,000
75
30,603
-84
*j _ 2
7.7
2-5
0. 2
0.7
C.j
L.U
1.7
0.7
0.7
0 . 7
0. 3
-.9
.I1- . O
-* . *
i?. i
0. 7
*2.cL
22.9
2.5
0.7
15.0
39.3
9-5
0.3
0.3
0.5
19.2
27. C
29.2
22.1
22.8
0.6
0.9
19.8
20.0
2.6
175.5
55.5
21*. 0
21.2
14.7
31*. o
8.6
28.1
9-9
3.0
0.4
33.6
31.8
2.1*
11.1*
2.7
9.3
29.2
9.0
18.0
08 /
200
250
150
<10C
9,8co
5 , 500
150
2C
<100
<100
100
<100
-C
200
2/JOC
500
200
3,70C
260
70
2,000
1,200
850
650
400
180
4,200
50
500
1*80
250
70
70
60
250
<10
20
30
25
<10
60
120
80
110
iBo
150
<10
<10
<10
10
250
<10
<10
21*0
<10
380
py
8.0
7.0
-j .8
7- 3
".5
7.3
j.'j
6.6
7. i
7.3
o. 7
o.7
-7.Q
o.o
7.4
7.8
7.8
7.7
5.5
7.6
7.5
6.9
7-3
7.6
7.6
7-3
7.8
7.8
7.6
7.8
7.7
7-9
8.0
7-7
7.7
8.1*
8.3
8.1
7.9
7.8
8.1*
7.6
7.9
7.6
7.0
5-9
7.5
7.9
6.6
7-4
7.8
7.7
8.1
7.5
7.7
AU.
as
-3, t
52.0
"7 0
', .:
5. 0
i > . :
'-'..-
'^.2
4.0
12. 0
i" . :
'6.C
22.0
17.0
10 6.0
<-5
24.0
260.0
275.0
0.4
100.0
28.2
673.0
5.6
23.2
2S.4
186.0
116.0
270.0
144.0
180.0
^9.0
82.0
103.0
136.0
53.0
292.0
160.0
120.0
120.0
122.0
140.2
21.0
150.0
28.4
23.0
0.9
11*5.6
171.0
12.0
65.2
1*6.2
59.2
200.0
37.6
147.7
7on i.
- - 6 ,
75
76
6
17
^^
5<,
70
15
32
.'6
-------
TABLE C-l
CHEMICAL CONCENTRATIONS IN PO:rCS (ASSAYS 2-b)
1968
Date
June 13
[Assay
Started
June 12]
June 18
June 20
June 25
June 27
July 1
July 8
[Assay
Started
July 51
July 10
July 12
Assay No.
(S, days)
2
(10)
11
"
"
11
"
"
"
"
"
"
"
"
»
"
"
11
"
"
"
"
"
"
11
11
"
"
"
"
"
11
11
"
"
"
11
"
..
"
"
"
«
"
ii
"
Pond
Mo.
1
2
3
it
5
6
7
8
1
2
3
it
5
6
7
8
1
2
3
it
5
6
7
8
1
2
3
It
5
6
7
8
1
2
3
It
5
6
7
8
1
2
3
It
5
6
7
8
Influent8
Description
LOT
0.1 III
1.0 III
1.0 III
LOT
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1.0 III
LOT
0.1 II
1.0 II
1.0 II
LTH
0.1 III
1.0 III
1.0 III
LOT
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1.0 III
LOT
0.1 II
1.0 II
1.0 II
LOT
0.1 III
1.0 III
1.0 III
LOT
0.1 II
1.0 II
1.0 II
LOT
0.1 III
1.0 III
1.0 III
LOT
0.1 II
1-0 II
1.0 II
Concentrations, [ig/t
N03-N
1*3
ItO
"0
U2
Itl
ItO
>»3
39
32
33
28
53
23
29
6U
73
<5b
<5
<5
<5
<5
11
5
2
13
3
1
<1
<1
1
1
1
it
it
1
1
<1
1
6
12
11
12
11
It
11
5
NH3-N
270b
200
200
150
290
280
270
330
182
197
220
235
235
250
2Uo
280
186
198
193
178
216
178
153
173
200b
230
200
220
215
200
200
205
2ltO
l^
185
185
193
170
367
285
235
170
282
210
215
190
300
100
Total p(
186
255
195
195
233
173
161*
2ll
2ltl
155
189
189
194
206
It27
351
kn
It62
513
3lt2
306
21k
It2l
196
P04-P
7
7
10
7
7
7
7
7
6
3
3
7
3
7
20
25
It
2
2
2
It
6
27
25
2
<1
2
<1
3
It
7
6
1
t
7-1*
7-5
7-5
7-6
7-8
7-9
7- U
7-8
7-7
7-7
7-8
7-8
7-1*
7-7
7-8
8.0
7-8
7-8
7-7
8.9
7-5
7-7
7-7
7-6
7-7
7-6
8. it
8.1
7-7
7-9
8.2
8.2
7-9
7-8
8. it
8. It
7-8
7-5
7-9
7-8
7-8
7-8
7-9
8.0
Conductivity
10"s mhos
91
91
90
90
90
90
90
91
108
87
91
89
87
89
92
90
92
93
9k
90
gk
91
90
93
100
93
96
98
96
92
96
98
98
9lt
96
97
95
95
96
96
100
98
98
98
98
95
96
98
Alkalinity for ponds 1, 2, 3 was kZ.8, k2.8>, and 1*3.2 nig/£ as CaC03 for June 30, 1968.
3
(5)
ii
||
"
"
"
:
ii
n
»
"
"
fi
M
"
"
n
M
n
1
2
3
l+
5
6
7
8
1
2
3
It
5
6
7
8
1
2
3
l*
5
6
7
8
LTW
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1.0 III
LOT
0.1 II
1.0 II
1.0 II
LOT
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
LOT
0.1 III
1.0 III
1.0 III
7
9
7
8
6
5
8
5
2
3
3
2
3
2
12
13
9
10
6
26
5
10
23
27
109
105
108
96
91
93
95
88
227
210
330
225
75
62
35
69
130
110
20
100
55
65
92
100
326
288
393
297
130
131
112
137
12*
3
7
3
<1
<1
-------
TABLE C-l (Continued)
1968
Date
July 15
July 17
July 19
July 22
July 2k
July 26
July 29
Aug 5
[Assay
Started
Aug 2]
Aug 7
Assay No.
(6, days)
3
(5)
"
11
"
"
11
»
11
"
"
"
"
"
"
»
11
"
"
"
11
11
"
"
11
11
11
J1
"
"
"
Pond
No.
1
2
3
It
5
6
7
8
1
2
3
4
5
6
7
8
l
2
3
It
5
6
7
8
1
2
3
it
5
6
7
8
Influent
Description
LTW
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
LTH
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1.0 III
Concentrations, pg/ ' t
N03-N
7
6
7
28
5
lit
38
ItO
11
10
8
8
6
5
37
58
18
21
lit
21
16
16
33
92
5
2
5
5
12
8
16
1*3
NH3-N
150
140
80
100
62
37
80
100
147
132
180
120
140
118
194
157
65
55
70
81t
67
61
57
61
47
37
90
45
70
32
110
118
Total N
225
210
248
204
209
185
318
335
P04-P
i
3
21
57
L!10
275
250
205
205
208
275
200
236
312
175
136
250
200
347
336
586
534
4oi
396
305
316
4l4
479
301
253
437
<1
5
11
15
7
1
<1
<1
3
3
16
18
2
-------
TABLE C-l (Continued)
1968
Date
Aug 9
Aug 12
Aug 14
Aug 15
Aug 21
[Assay
Started
Aug 16]
Aug 23
Aug 26
Aug 27
Assay IIo.
(9, days)
k
(3)
"
tl
tT
11
It
tl
11
It
"
II
(I
11
"
"
It
II
11
tl
"
11
It
It
It
"
"
"
II
tl
It
"
5
(3)
II
It
"
"
"
"
It
It
It
"
"
It
It
"
»
11
11
It
tf
»
"
rt
"
"
it
if
it
"
M
M
Pond
No.
1
2
3
it
5
6
7
8
1
2
3
k
5
6
7
8
1
2
3
It
5
6
7
8
1
2
3
It
5
6
7
8
1
2
3
It
5
6
7
8
1
2
3
it
5
6
7
8
1
2
3
it
5
6
7
8
I
2
3
it
5
6
7
8
Influent
Description
Seed Tank
0.1 III
1.0 III
1.0 III
LTW
o.i n
1.0 II
1.0 II
Seed Tari
0-1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
i.o n
Seed Tank
0.1 III
1.0 III
1.0 III
LW
0.1 II
1.0 II
1.0 II
Seei Tank
0.1 III
1.0 III
1.0 III
LTV
0.1 II
1.0 II
1.0 II
Seei TarL-:
0.1 II
1.0 II
1.0 II
LTW
0.1 HI
1.0 III
1.0 III
Seed Tank
0.1 II
1.0 II
1.0 II
LOT
0.1 III
1.0 III
1.0 III
Seed Tank
0.1 II
1.0 II
1.0 II
LW
0.1 III
1.0 III
1.0 III
Seed Tank
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1.0 III
Concentrations, Mg/^
N03-N
9
50
108
3
6
78
43
11
58
62
<1
<1
64
1
11
itit
54
1
2
2
2
6
3
17
3
5
22
18
<1
1
lit
<1
<1
17
30
5
2
2
3
5
40
38
NH3-tf
162
225
200
175
175
225
235
65
122
120
45b
55
30
26
27
87
73
<5
It2
10
5
29
112
67
8
40
<5
<5
80
lt6
1*2
37
36
Ui
69
50
ito
38
46
57
67
75
10
8
33
8
60
64
55
Total K
164
216
115
181
227
224
255
P04-P
<1
1
3
-------
TABLE C-l (Continued)
1968
Date
Aug 28
Aug 29
Aug 30
Sept 6
[Assay
Started
Sept l]
Sept 9
Sept 11
Sept 13
Sept 16
Sept 18
[Aerated to
bring
down pH]
Assay ": .
(e, days)
5
(3)
11
"
11
11
11
"
"
11
IT
"
"
tt
11
11
Pond
No.
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
Influent
Description
Seed Tank
0.1 II
1-0 II
1.0 II
LTH
0.1 III
1.0 III
1.0 III
Seed Tank
0.1 II
1.0 II
1.0 II
LOT
0.1 III
1.0 III
1.0 III
Concentrations, [Jg/-2
N03-N
4
3
2
2
k
4
<1
NH3 -IT
85
130
80
49
148
195
106
Total N
789
603
-
361
492
426
P04-P
<1
22
15
<1
<1
<1
<1
Total P
12
25
19
<1
4
3
7
pH
7-9
8.1
8.1
8.0
7-8
8.0
8.1
Alkalinity for ponds 2} 3, h was 51AO, 52. kO, and 52. 60 rug/ £ as CaC03 .
"
"
"
11
11
"
"
"
6
(10)
"
it
"
"
"
"
"
"
"
"
"
"
-
11
"
"
"
"
"
"
"
ir
"
it
n
11
"
tr
"
"
"
11
"
"
"
ii
"
it
"
19
"
"
"
1
2
3
4
5
6
7
8
l
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
it
5
6
7
8
1
2
3
4
5
6
7
8
Seed Tank
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1.0 III
1.0 II
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
1.0 II
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
1.0 II
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
1.0 II
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
1.0 II
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
1.0 II
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
9
11
8
9
10
19
32
6
276
272
3ft
260
256
272
272
9
220
220
190
200
194
208
230
27
170
166
160
176
170
154
180
33
165
155
l4o
150
142
5
3
12
88
97
84
75
83
3
<1
7*
85
103
85
82
50
8
8
118
88
76
68
150
158
150
110
237
150
200
225
230
215
250
100
125
150
162
87
100
150
175
175
160
238
215
145
125
125
125
25
57
72
100
45
15
0
17
60
107
125
155
89
70
46
82
90
122
142
147
91
80
65
130
184
575
545
502
387
444
60S
510
257
387
325
332
180
151*
113
204
5
26
27
<1
l
<1
<1
5
<1
<1
<1
<1
<1
3
3
23
<1
<1
<1
<1
<1
12
18
39
2
<1
<1
<1
<1
6
7
31
<1
<1
<1
<1
<1
<1
<1
23
<1
<1
<1
<1
<1
<1
<1
50b
<1
<1
<1
3
<1
<1
8
4o
8
3
3
12
2
4
5
50
5
7
3
4
7
5
9
7.8
7-9
7-9
7-9
7-8
7-9
7-9
7-8
3.0°
3.0
7-9
7-9
7-9
7-9
8.1
7-6
7-9
8.0
8.0
8.1
8.1
8.4
8-5
7-9
7-9
8.1
8.0
8.0
8.1
8-9
8-7
7.8b
7-9
7-9
7-9
7-9
8.0
9-2 (8.1)
8.7 (8.0)
Conductivity
10~6 mhos
84
88
90
88
85
90
89
87
88
86
84
86
85
86
86
9lb
91
95
94
92
92
93
9k
92
95
96
92
gk
93
91
94
93
94
94
92
92
90
91
95b
92
96
94
93
92
94
95
112
-------
TABLE c-1 (Continued;
1968
Date
Sept 20
Sept 23
Sept 25
Sept 26
Sept 30
Oct 2
Oct k
Oct 7
[Assay
Started
Oct 5]
Oct 9
Assay Ho.
(e, days)
6
(10)
11
11
"
II
"
"
"
"
"
11
"
II
"
It
"
"
11
It
"
"
"
"
"
11
"
11
11
11
"
I)
II
II
"
"
"
"
TI
"
Pond
No.
1
2
3
k
5
6
1
8
1
2
3
1*
5
6
7
8
1
2
3
1*
5
6
7
8
1
2
3
k
5
6
7
8
1
2
3
1*
5
6
7
8
Influent
Description
1.0 II
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
1.0 II
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
1.0 II
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1-0 II
1.0 II
1.0 II
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
1.0 II
0.1 III
1.0 III
1.0 III
LW
0.1 II
1.0 II
1.0 II
Concentrations, iJg/^
N03-N
k
60
98
70
53
3
2
2
7b
1*7
83
73
1*3
5
5
k
1
28
82
60
23
<1
<1
-------
TABLE C-l (Continued)
1968
Date
Oct 11
Oct 15
Oct 1?
Oct 18
Oct 21
Oct 23
Oct 25
Oct 28
Assay lie
(i, days)
7
(5)
"
"
"
"
"
"
"
"
"
"
11
"
"
"
"
"
"
"
"
"
"
"
"
"
11
"
11
"
"
"
"
"
"
"
"
"
tl
"
It
"
"
"
"
"
"
"
11
11
"
"
M
11
!1
"
"
"
"
"
Pcr.i
l',c .
T_
2
3
^
5
f.
Y
3
1
2
3
L
5
£
7
3
1
2
3
i+
5
h-
7
3
1
2
^
l
5
f
7
3
1
2
3
4
5
6
7
3
l
2
3
4
5
6
V
1
8
1
2
3
li
5
6
7
8
1
2
3
4
5
6
7
8
Ir_fluer.t
Description
LTW
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1-0 III
LTW
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
Concentrations, Mg/^
NO,,-N
5
10
28
15
7
3
3
3
6
f-
13
11
3
1
<1
<1
5
3
10
7
2
2
1
2
5
4
10
7
3
2
2
3
12
10
14
12
7
8
6
6
22
21
23
25
17
17
13
17
11
10
11
15
12
8
8
11
MH3 -II
72
100
167
190
130
25
92
45
61
100
282
253
109
58
110
63
47
57
395
385
53
42
52
46
47
83
280
280
59
87
47
59
25
50
250
275
32
22
15
<5
16
18
275
238
16
34
16
8
Total N
266
281
330
4i4
268
201
217
195
294
338
501
489
191
232
203
240
P04-P
<1
3
<1
<1
<1
<1
13
18
3
<1
1
<1
<1
<1
4
11
<1
<1
<1
<1
<1
<1
10
15
<1
<1
<1
<1
<1
<1
7
4
<1
<1
<1
<1
<1
<1
8
6
<1
<1
<1
<1
<1
<1
<1
3
4
<1
4
<1
<1
<1
7
6
Total P
11
4
3
2
5
3
7
18
6
<1
3
11
4
j
13
53
PH
7-8
7-9
7-8
7-7
7-7
7-7
8.2
8-3
7-3
7-6
7-7
7.6
7-6
7-6
7-8
8.0
8.3
8.9
7-4
7-5
7-5
7-5
7-5
7-5
7-7
7-9
Conductivity
10 8 mhos
85
91
94
93
85
82
82
84
96
90
92
91
94
93
91
91
92
90
95
95
88
89
92
91
-------
TABLE c-j- (Continued)
1968
Date
Oct 30
Oct 31
Nov 1
Assay No.
(0, days)
7
(5)
tr
11
11
"
"
11
"
"
"
11
"
11
11
"
"
"
I!
It
"
It
II
Pond
No.
1
2
3
1*
5
6
7
8
1
2
3
1*
5
6
7
8
1
2
3
4
5
6
7
8
Influent
Description
LTW
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
LTW
0.1 III
1.0 III
1.0 III
LTW
0.1 II
1.0 II
1.0 II
Concentrations, Mfi/-^
K3,-:;
15
12
lU
il
9
9
6
9
10
7
10
9
it
6
5
6
:CH, -H
33
it
163
200
-3
70
5
18
<5
<5
200
250
2lt
57
23
57
Total H
173
116
26^4
351
152
129
63
16U
P04-P
2
<1
<1
<1
<1
<1
3
3
<1
<1
<1
<1
2
1
3
3
Total P
13
3
26
5
ll*
3
23
13
PH
8.7
8.6
7-9
7.8
Conductivity
10 "6 mhos I
91
90
BCor.troI is pond containing La/.e Tahoe vater only; II is secondary effluent; III is tertiary effluent; 0.1 and
1.0 refer to the percent effluent in La/.e Tahoe water.
For r.cted rerultr sampler, for those £ pcr.is collected cr. day following listed date.
115
-------
TABLE C-2
RESULTS OF ANALYSES OF POND INPUT WATERS
1968
Date
May 9
21
29
June 5
11
19
27
July 9
lit
15
17
21
25
29
Aug 2
7
9
12
16
23
28
Sept 9
13
22
29
a
Sample
II
III
II
III
II
III
II
III
II
III
II
III
II
III
II
III
II
III
MID LTW
II
III
II
III
II
III
II
III
II
III
II
III
MID LTW
II
III
II
III
II
III
II
III
II
III
MID LTW
SHORE LTW
II
III
II
III
II
III
Suspended
Solids
mg/J
_
-
-
.
-
-
-
-
-
_
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
5.02
1.01
-
-
-
-
-
-
-
(2) 15.6
(2) O.J28
3.28
0.23
-
-
-
-
5.46
1-74
12.04
0.17
Volatile
SUB pe tided
Solids
mg/Jt
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
3.20
0.68
-
-
-
-
-
-
-
13- 74
0.43
3-33
0.50
-
-
-
-
5.82
1.68
11.74
0.38
Chemical Analyuetj, mg/£
N03"
5-0 .
3.8
3-3
2.8
7.6
7-2
4.0
5.8
6.8
7.4
9-5
15-7
1.4
5-7
5-0
3-1
6.0
6.4
0.005
5-1
8-3
3-7
6.1
10.0
7.9
6.1
7-9
4.2
8.2
8.2
9-3
<1
4.2
3.7
6.4
5-6
0.68
5-3
1.8
2.0
9-1
2.8
<1
0.001
2.9
6.1
5-0
6.7
0-7
3-0
N02"
1-3
3.6
0.7
0.4
1.4
0.12
3-2
1.4
1.6
l.l
1.6
1-7
0.56
0.12
1.2
0.66
0.84
1-3
0.001
0.58
1-9
0.44
1-5
0.80
0.96
1-9
2.1
0.80
2.0
0.',4
1-7
<1
1-3
0.06
1.1
0.16
1-3
0.12
0.5
0.014
0-5
0.86
<1
<1
1-3
0.09
0.28
0.04
0.6
0.28
NH3
1-3
6.2
4.1
5-9
2.8
6.4
4.8
7.2
4.0
9-7
6-5
7-8
17-5
12.6
8.2
15-8
18.0
9-8
0.060
13-5
9.0
23.8
21.4
8.4
14-5
12.8
12.4
12-5
11.0
11.2
8.5
0.018
7-8
13-2
10.0
13.0
23.2
17-5
17-8
18.8
11.2
15.0
0.063
0.045
9-5
9-8
9-7
9-8
22.5
13-7
Organic
N
1.2
1.3
1.2
1.4
1.0
0.8
2.5
0.8
1.0
0.65
1.3
1.0
1-9
1.3
1-5
1.2
1.6
1.0
0.095
1.3
0.55
1.7
l.l
1.2
0.50
1-3
0.80
1.9
1-5
1.2
0.82
0.070
1.0
1.1
2.3
1.8
1.4
1.4
1.2
1.0
1.3
l.l
0.061
0.029
1.3
1.2
1.3
0.78
1-9
0.77
Total
N
8.8
14-9
9-3
10.5
12.8
14-5
14-5
15-2
13-4
18.8
18.9
26.2
21.4
19-7
15-9
20.8
26.4
18.5
0.161
20.5
19.8
29.6
30.1
20.4
23-9
22.1
23-2
19-4
22.7
21.1
20.5
0.088
14.3
18.1
19-8
20.6
26.6
24.3
21-3
21.8
22.1
19-8
0.124
0.075
15.0
17.2
16.3
17.3
25.7
17.8
P04~
3-1
0.43
5-0
2.6
6.1
0.9
6.4
0.8
6.2
1.8
7-5
1.0
10.0
0.56
8.8
1.4
8.8
0.54
<5
9-8
0.54
9-0
0.62
8.8
0.60
0.6
1.0
7-0
0.26
7.1,
0.56
0.005
10. (,
0.42
6.6
0.6
7.4
0.58
7-6
0.7
4.9
0.095
<1
<1
5-4
0.19
11.4
0.44
6.7
0.15
Organic
P
2.8
2-5
0-3
0.2
0.4
0
0.2
0
0.3
0
2-5
0.6
0.4
0.4
1.4
0.1
0.8
0.1
<5
0.4
0.1
0.2
0.02
0.60
0.03
0.4
0
0.2
0.1
0.4
0.04
0.005
0.46
o.o4
0.1
0.025
1.0
0.014
0.6
0.025
0.2
0.01
<1
0.003
0.7
0.03
1.0
0.05
0.78
0.026
Total
P
5-9
2.9
5.3
2.8
6.5
0.9
6.6
0.8
6.5
1.8
10.0
1.6
10.4
1.0
10.2
1-5
9.6
0.6
<10
10.2
0.64
9.2
0.6
9.4
0.7
9.0
1.0
7.2
0.4
8.0
0.6
0.010
11-1
0.5
6.7
0.62
8.4
0.39
8.2
0.72
5-1
0.1
<2
0.003
6.1
0.22
12.4
0.49
7-5
0.18
PH
7-9
7-8
8.0
7-9
7-9
7-7
7-9
7.7
7-7
7-7
7-7
8.2
8.0
8.1
7-9
8.3
8.0
8.2 -
7-8
8.1
8.2
8.0
7.8
7.4
7-7
0.0
8.1
7-7
9-0
7-7
7-8
7-7
7-9
8.2
7-9
8.0
7-9-
8.0
8.0
7-9
7-8
8.2
7-7
7-7
8.0
8.0
7-7
7-9
8.2
7.8
Conductivity
480
510
437
455
432
495
500
545
485
540
485
500
450
500
412
500
580
580
83
475
538
539
556
519
500
490
500
454
470
5-5
51 .2
'('(
450
615
460
450
454
509
48o
1,10
4 oo
576
82
81
4io
54o
385
48o
54o
530
CaC03
Alk.
143
160
165
165
114
185
148
173
U9
180
112
187
193
226
14)
212
181
189
4l
162
201
174
192
110
195
117
151
13'-
Hi.
154
194
50
120
220
138
224
184
237
191
250
131
265
42
42
191.
231
122
256
2ir,
28f,
Cl"
50
35
50
59
28
,. j
28
51
22
54
28
24
29
',),
25
55
:'(
29
0.2
2y)
',1
5i
20
4o
Mi
5'l
44
',-',
4i,
28
37
1.4
'/>
~j j
25
30
2^
50
22
30
22
21
i.l
0.5
20
2 5
20
25
22
;.'4
Fe
0.015
<10
0.015
<10
<10
<10
0.020
<10
<10
<10
0.015
<10
<20
<10
0.013
0.011
<10
<10
<10
0.012
<10
0.012
0 . 020
0.025
<\Q
0.018
<10
<10
<10
0.012
<10
<10
<10
<10
0.012
<10
0.012
<10
0.017
<10
<10
0.020
<10
_
<10
0.011
<10
0.010
0.053
0.021
BOD
2
0
17
J
c
J
1
9
l
(
1
<
2
0
0
8
0
',
0
-
I,
0
12
0
(
1
4
0
15
i
11
0
0
10
0
c
0
15
0
14
0
7
0
-
_
-
-
10
2
if.
d.
COD
26
25
'0
20
-', [
i:',
III
27
27
y
'(
20
5J
i
r 2
i-',
Ci'i
54
-
' 5
2]
87
24
7'
50
70
',4
'(',
52
84
4o
_
. 4
',,
(9
4,,
4o
i4
54
i ,
20
j
_
50
2
49
0
9''
0
-------
TABLE C-2 (Continued)
1968
Date
Oct 3
4
8
11
16
22
23
24
27
Sample
II
III
MID LTO
SHORE LTH
II
III
II
III
II
III
II
III
LTO
II
III
II
III
Suspended
Solids
mg/i
_
-
-
-
17.30
1.13
2k. 69
2.39
16.09
1-73
10.52
1.16
0.35
-
17-05
3.22
Volatile
Suspended
Solids
mg/.e
_
-
-
-
17-22
1.13
21-77
2.16
-
-
_
_
0.28
-
-
-
"
Chemical Analyses, rag//
N03-
0.014
0.067
o.ook
0.002
0.026
0.014
0.005
0.019
0.015
0.013
0.001
0.048
_
0.015
0.030
0.009
0.048
N02-
0.004
0.002
<1
<1
0.017
0.003
0.002
<0.001
0.015
0.018
0.013
0.034
-
0.009
0.042
0.021
0.020
NH3
21.1
28.0
0.048
0.029
15.2
27.8
5-2
24.0
28.60
26.60
29.00
28.75
-
25.50
22.75
32.5
26.0
Organic
N
1-7
0.61
0.175
0.125
1.8
0.65
1.76
1.00
1.725
1.125
1.940
1.520
-
1.56
1.20
1.65
1.22
Total
N
22.8
28.7
0.227
0.156
17-0
28.5
4.97
25.0
30.4
27.8
51.0
30.4
_
27-1
24.0
34.2
27.3
po4-
5.8
0.086
<1
<1
7-3
0.185
5.44
0.11
7-2
0.12
7-36
0.60
_
7.10
0.68
7.00
0.54
Organic
P
0.16
0.022
<1
0.002
0.4
0.01
0.240
<0.005
0.44
0.008
0.32
0.01
-
0.50
0.06
0.30
0.06
Total
P
6.0
0.11
<2
0.002
7-7
0.2
5.68
0.11
7.64
0.13
7-68
0.61
_
7-60
0.74
7-30
0.60
pH
8-3
7-9
-
7-7
7-7
7.6
8.4
8.0
8.0
8.1
8.0
8.8
_
8.1
8.8
8.0
9-0
Conductivity
442
520
83
83
400
462
460
510
5?5
510
520
480
_
420
^35
475
48o
CaC03
Alk.
218
276
-
^
187
241
238
276
242
238
188
202
_
191
202
203
211
Cl"
52
57
2.0
1-7
38
59
2'
45
',k
55
30
35
-
28
34
',1
44
Fe
<10
0.012
<10
<10
0.024
0.012
0.020
0.040
0.007
0.013
0.045
0.010
-
0.012
<5
0.025
<5
BOD
33
2
-
-
25
4
34
-------
TARLK C-'j
PILOT POND ANALYSES
Date
1969
7-1'*
7-16
7-17
7-18
7-21
Pond
Detention
Time
9
dnys
8
A. -.ray
No.
1
8
Assay
No.
1
8
A:; nay
No.
1
8
Assay
No.
1
8
Assay
No.
1
Pond
No.
1
2
3
1.
5
6
7
8
1
2
3
it
5
6
7
8
l
2
3
it
^
6
7
8
1
2
3
it
5
6
7
8
1
2
3
it
5
6
7
8
Influent
Description
LTW8
0.1$ II
1$ II
J$ G-II
LTW
0.1$ II
1$ II
1$ S-II
LTW
0.1$ II
1$ II
1$ G-II
LTW
0.1$ II
1$ II
1$ G-II
LTW
0.1$ II
1$ II
1$ G-II
LTW
0.1$ II
1$ 11
1$ G-II
LTW
0.1$ II
1$ II
1$ S-II
LTW
0.1$ II
1$ II -
1$ S-II
LTW
0.1$ II
1$ II
1$ S-II
LTW
0.1$ II
1$ II
1$ S-II
Temperature
°C
21.7
18.7
21.1
22.1*
23.8
Unfiltered Camples
Suspended
Solids
mgA
0.76
1.01
0.')8
0 . 92
0.69
0.75
0.81
0.81
2.15
2.57
2.73
3.1(0
1.76
1.66
3.06
2.1(6
1.75
2.97
5.65
1(.02
2.10
2.73
!+.20
5.1('(
1.99
It. 66
9.79
3.85
2.27
3.39
9-27
9. '87
Volatile
Suspended
Solids
rag A
0.1(2
0.15
0.6o
0.1.3
0.69
0.25
0.1*9
0.60
0.81*
1.33
1.18
0.51*
0.70
1.38
l.llt
0.86
1.33
3.69
2.10
0.76
1.29
2.33
3.18
1.38
2.57
5.26
2.63
0.8U
2.01
1*.91
i*.86
Nitrogen as N
Organic
MgA
88
85
86
8U
72
51*
100
66
NH3
US A
32
25
155
330
39
26
160
355
Total
Phosphorus
MS A
32
32
83
300
13
232
73
185
19
22
85
75
38
28
61*
93
GF/C Filtered Sample
Nitrogen as N
Organic
MS A
60
79
8L
101*
93
60
120
86
12
83
27
32
<5
58
116
121
.NH3
MS A
25
<5
116
325
<5
<5
72
325
30
1(0
56
92
9
31
31
86
39
36
20
16
18
1*.
<5
10
6h
6k
92
62
6
1*6
51
52
N02-N03
MS A
It
2
30
-------
TABU! C-3 (Continued)
Date
7-23
7-25
7-28
7-30
8- 1
Fond
Detention
Time
B
days
8
Assay
No.
1
8
Assay
No.
1
8
Assay
No.
1
8
Assay
No.
1
8
Assay
No.
1
Pond
No.
1
2
3
1*
5
6
7
8
1
2
3
k
5
6
7
8
1
2
3
It
5
6
7
8
1
2
3
It
5
6
7
8
1
2
3
it
5
6
7
8
Influent
Description
LTW
0.156 II
15* II
156 s-n
LTW
0.156 II
156 II
156 s-n
LTW
0.156 II
156 II
156 s-ii
LTW
0.15fe II
1.056 II
156 s-ii
LTW
0.156 II
156 II
156 s-ii
LTW
0.156 II
156 II
156 s-ii
L1W
0.156 II
156 II
156 s-ii
LTW
0.156 II
156 II
156 s-ii
LTW
0.156 II
156 II
156 s-ii
LTW
0.156 II
156 II
1$ S-II
Temperature
°C
24.7
23.8
23.1
23.0
24.8
Unfiltered Samples GF/C Filtered Samples
Suspended
Solids
mgA
1.91
3.31
7.10
3.50
2.14
3.20
10.46
12.01
1.96
3.85
9-92
10.89
2.59
3.54
10.60
11.11
0.71
3.03
9.92
7.55
2.04
2.73
10.43
lO.B'i
1.05
2.93
10.67
8.57
2.04
2.81
11.25
10.41
2.11
5.50
12.11
12.22
2.85
11.97
12.4l
Volatile
Suspended
Solids
mgA
0.78
1.12
3.79
1.75
0.76
1.16
5.03
5.19
0.89
1.48
4.81
5.00
0.84
1.43
4.96
5.27
0.71
1.38
4.94
4.03
0.82
1.24
5.08
4.08
0.83
1.87
5.28
5.46
0.90
5.43
4.83
Nitrogen as N
Organic
MgA
NH3
Mg/*
Total
Phosphorus
MgA
Nitrogen as N
Organic
MgA
13
38
55
44
30
22
46
76
NH3
MgA
54
50
56
36
39
38
28
62
45
25
34
38
28
26
10
70
54
20
45
20
10
12
10
P.6
0
8
22
10
4
18
36
30
11
8
<5
14
14
38
30
14
N02-N03
MgA
2
10
4
3
6
8
3
1
5
1)
4
6
6
2
6
6
4
1
2
3
2
1
<1
<1
5
5
3
3
5
5
4
3
6
7
8
6
7
6
8
5
Total
MgA
73
59
102
67
42
35
56
102
Phosphorus
as P
P04
MgA
4
5
12
23
5
6
8
19
3
3
8
17
3
3
12
14
1
3
15
22
3
3
15
23
2
3
\4
22
2
3
15
23
3
4
18
23
2
4
19
23
Total
MgA
4
7
20
28
13
14
26
28
9
10
20
24
11
9
27
28
4
7
28
31
7
10
28
31
7
28
22
32
4
11
33
34
8
20
31
33
5
16
32
30
Fe
MgA
Cond.
(io-s)
mhos
97
97
99
96
95
96
98
95
95
91
99
98
92
97
100
98
pH
7-9
8.0
8.5
8.6
8.1
8.1
8.5
8.8
7.4
7.9
8.2
8.1 '
8.0 '
8.0
8.4
8.1
7-9
8.0 ;
8.2
8.2
8.0
8.0
8.5
8.0
7.8
7.9
8.2
8.2
7.9
7-9
8.2
8.1
8.0
8.1
8.4
8.4
8.0
8.1
8.3
8.3
-------
TABLE C-3 (Continued)
Date
Pj. 1,
8- 5
8- 6
8- 7
8- 8
Tond
Detention
Time
g
days
8
Annuy
No.
1
8
Assay
No.
1
8
Assay
No.
1
8
Assay
No.
1
8
A:xny
ND.
1
Pond
No.
1
2
3
u
5
6
Y
8
1
2
3
it
5
6
7
8
1
2
3
k
5
6
1
8
l
2
3
l)
5
6
7
8
1
',
ii
5
6
7
8
Influent
Description
LTW
O.ljt II
1% II
1$ G-II
LTW
0.156 II
J$ II
1$ C-JI
LTW
0.156 II
1% II
156 s-n
LTW
0.156 II
156 II
156 s-n
LTW
0.1$ II
156 II
156 G-II
LTW
0.1$ II
1$ 11
1$ G-II
LTW
0.156 II
156 II
1$ S-II
LTW
0.1$ II
1$ II
1$ S-II
LTW
0.1$ II
J$ 11
L'f, ,",-11
LTW
0.1$ II
1$ II
1$ S-II
Temperature
°C
22.6
21.8
21.lt
21.1
21.6
Jr,''iltercd ;,:u.,plcs
Suspended
Golids
rag /I
1.80
3.7'*
12.75
10.51
1.01
2.68
1 J . 50
12.7'+
? P6
1^52
12.51*
12.3!+
2.50
3.56
12.39
13.21
2.55
Ii.'i2
1U.25
12.61
?. 28
3-56
13.52
l'*.56
2.53
'1.07
13-72
12.1*3
1.73
3.16
12.9'*
16.39
o.T5
;'.BH
!.;'.'/>
l.L.;'l|
2.33
3-52
11.87
lit. 69
Volatile
Suspended
Golids
me A
0.82
1.27
5-51
14.66
0.68
I. 10
5.0'l
5.15
1.00
1.55
5.37
5-21
0.8k
1.U8
5.20
5-36
1.07
1.70
6.31*
5.65
0.82
1.1*1
5.87
6.27
0.75
1.2J
<>.'A
II.IM
0.63
1.21
i*.6o
5.<*3
Nitrogen as N
Organic
MgA
91
80
,"'10
170
62
70
15U
198
NH3
MS A
1*0
l|(l
V)
;<>
32
31
29
1+0
Total
PhoGpliorus
MS A
23
35
101.
1K>
22
33
110
107
GF/C Filtered Samples
Nitrogen as N
Organic
MgA
32
35
62
71
?3
27
67
36
70
OP
lly
IU)
57
75
106
111
WH3
MS A
1*
20
9
30
15
9
15
9
2U
2U
18
22
9
20
6
18
39
?h
V,
T'L
1*1*
1*2
28
1*1*
N02-N03
MS A
3
2
2
2
2
2
2
1
7
6
6
6
6
7
8
7
11
10
10
1.0
10
10
9
10
Total
MgA
59
57
73
103
1*0
38
81*
1>6
120
IPfi
i-;;'
117
111
127
I'O
165
Phosphorus
as P
P04
MS A
2
1)
13
19
2
1*
15
16
it
7
11
19
3
6
18
13
2
1
1?
i.a
2
1*
10
10
Total
MS A
5
11
20
25
1*
9
no
on
21*
3"t
32
63
lit
39
38
Hi
23
U
*s
'i:'
20
23
22
70
Fe
MgA
8
<1
<1
<1
<1
2
<1
<1
Cond.
(io~6)
mhos
90
92
91*
93
89
91
9'i
93
95
02
o.1
Oil
yl,
91
91*
95
PH
7-8
7.9
8.6
8.2
8.1
8.1
8.7
8.5
7.9
7-9
8.3
8.2
8.0
8.0
8.3
8.1*
7-9
8.0
8.2
8.1
8.0
8.0
8.1*
8.1*
H
ro
o
-------
TABLE C-3 (Continued)
Date
8-11
8-1?
8-15
8-18
8-19
Pond
Detention
Time
e
days
5
Assay
No.
2
5
A;; ray
lio.
'fi
5
Assay
No.
2
5
Assay
No.
p
5
Assay
No.
2
Pond
No.
1
2
J
It
5
6
T
8
1
2
3
it
^
6
7
8
l
2
3
It
5
6
7
8
1
2
3
it
5
6
7
8
1
2
3
it
5
6
7
8
Influent
Description
LTW
0.1$ II
yd ii
1$ S-II
LTW
0.1$ II
1% II
1% S-II
LTW
0.1$ II
1$ II
1$ n-ii
L'lW
0.1$ II
1$ II
1$ n-ii
LTW
0.1$ II
1$ II
1$ S-II
LTW
0.1$ II
1$ II
1$ S-II
LTW
0.1$ II
1$ II
1$ R-II
LTW
0.1$ II
1$ 11
1$ S-II
LTW
0.1$ II
1$ II
1$ S-II
LTW
0.1$ II
1$ II
1$ S-II
Temperature
°C
23.2
22.2
23.1
22.5
22.0
UnTiltered Samples
Suspended
Solids
mg/C
1.66
3.80
12.52
13. "*3
1.83
2.67
13.56
13.75
1.69
3.63
12.38
15.68
P. 50
;>.<>')
12. ')6
13.'-"-)
2.25
2.72
11. 8U
13.6l
P.20
2.95
12.82
lit . 7'i
1.71
3.06
8. '18
l'i.73
2.21
2.38
11.89
13.79
2.71!
1.58
11.1*3
15.00
2.52
2.78
11.66
13.75
Volatile
Suspended
Solids
mpjl.
0.70
1.27
5. it it
5.69
0.56
0.91
5.61*
5-75
0.77
1.10
6.05
6.1*5
0.69
1.22
7-57
6.7't
0.62
1.00
5.0't
5.6'i
0.58
0.83
6.28
6.15
0.81
L.38
7.00
7-03
0.75
1.05
6.69
6.36
Nitrogen as N
Organic
MS A
NH3
v<
Total
Phosphorus
MS A
GF/C Filtered Samples
Nitrogen as N
Organic
MS A
99
120
113
123
81
80
138
li*9
69
96
101
98
75
88
Nil 3
Mg/8
35
32
24
38
1*5
63
55
39
3'*
1*5
!*7
33
30
20
22
25
1*2
1*0
50
59
39
84
87
63
1*6
39
1*8
31
51*
39
51
30
N02-N03
Me A
3
i+
-------
TABLE C-J
H
ro
ro
Date
8-20
8-21
8-22
8-25
8-27
Pond
Detention
Time
days
5
Assay
No.
2
5
Assay
No.
2
5
Assay
No.
2
3
Assay
Mo.
3
3
Assay
No.
3
Pond
}7o.
1
2
3
M-
5
5
7
8
1
2
3
it
5
6
7
8
1
2
3
it.
5
6
7
8
1
2
3
i*
5
6
7
8
1
2
3
it
5
6
7
8
Influent
Description
LTW
0.1* II
L% II
1% S-II
LTW
0.1% II
1% II
1% S-II
LTW
0.1% II
1% II
1% S-II
LTW
0.1$ II
1% II
1% S-II
LTW
0.1% II
1% II
1% S-II
LTW
O.lfo II
1% II
1% S-II
LTW
0.1% II
1% II
1% S-II
LTW
0.1% II
1% II
1% S-II
LTW
0.1% II
1% II
1% S-II
LTW
0.1% II
1% II
1% S-II
Temperature
°C
22.2
22.8
22.7
20.8
19.2
Unfiltered Sample;
Suspended
Solids
mgA
1.5&
3.0lt
11.88
12.UO
1.61
2.79
11.03
13. 71*
1.85
3.15
12.98
lit-. 87
1.93
2.91*
11.88
13.1*2
2.09
3-92
12.19
13.40
2.73
3.35
10.94
14.50
1.77
2.50
7.98
8.1*8
1.93
2.56
9-33
11.78
1.80
2.29
6.50
7.20
1.97
2.71
8.1*2
10.21
Volatile
Suspended
Solids
mgA
0.31
1.58
7.23
3-90
0.90
1.26
6.88
7.1*9
0.93
1.1*2
7. ok
5.20
0.78
1.27
7.23
6.50
0.63
0.82
i*.i*5
3.1*8
0.62
1.10
6.02
5-17
nitrogen *= 5
Organic
«A
144
li*7
25C
173
^33
107
226
198
-; 3
-s, I
31
16
33
3-
li*
12
8
6
Total
- c, ~ spri ZT u.5
VS/i
6
18
102
105
11
16
1C3
151
3F/C Filtered Sample;
Nitrogen as N
Organic
MS A'
loO
185
11U
9**
99
61
1,8
ic 6
,8
116
n't
122
90
95
9°
98
NK3
MS A
31
33
37
37
37
29
30
18
32
38
35
1*5
36
vo
32
20
48
52
ICO
49
-2
5-
70
44
24
31
30
40
33
35
31
36
NC2-SC3
MS/'
6
6
5
it
5
5
i4-
6
D
5
k
't
5
5
6
3
13
1C
7
7
11
6
7
5
13
16
12
8
15
13
11
7
Total
MS/''
198
228
153
193
140
106
186
129
109
178
221
178
143
155
173
147
Phosphorus
as P
FC4
MgA
3
13
16
21
2
6
~
15
f
9
11
32
i*
7
6
12
_
0
22
40
3
it
10
23
4-
6
21*
30
it
6
17
23
Total
Ms A
15
19
19
31
5
8
61
17
6
10
16
3^*
5
8
9
i£
4
20
31
15
6
53
19
28
7
12
30
37
7
9
20
21*
Fe
MS A
<1
<1
<1
<1
<1
<1
<1
<1
2
<1
<1
<1
1
<1
Cond.
' 1C 1
mhos
91
91
91
93
90
93
93
92
91
90
90
92
93
93
97
96
pH
8.0
8.1
8. it
8.7
8.0
8.2
8.u
8.7
8.1
8.0
8.6
8.2
8.0
8.0
8.7
8.1
8.1
8.1
8.2
8.1
8.1
8.2
8.2
8.3
8.G
8.C
8.5
8.4
8.0
8.1
8.8
8.7
8.5
8.5
3. it
3.4
-------
TABLE C-3
Date
3-29
9- l
9- 2
9- 3
9- 8
Fond
Detention
7i-~e
£3
days
i
Assay
So.
^
,
Assay
No .
T,
^
Assay
So.
3
5
Assay
No .
3
8
Assay
No.
1+
~on "*
Mo.
1
£
j
^
5
6
f?
8
1
2
3
4
5
6
T
8
1
2
3
4
5
5
T
8
1
2
3
i*
5
6
7
8
1
2
3
4
5
6
7
8
Description
LTV
0.1* II
1* II
14 S-II
LTW
0.1$ II
1$ II
l?c S-II
LTW
0.1$ II
1% II
lit S-II
LTW
0.1% II
1* II
lit s-ii
LTH
0.1$ II
1$ II
1% S-II
LTW
0.1?, II
1$ II
1$ S-II
LTW
0.1$ II
1$ II
1$ S-II
LTW
0.1$ II
1$ II
1$ S-II
LTW1'
2$ III
1$ III
1$ III + TE
LTW
2$ III
1$ III
1$ III -i- TE
.-e-rerat-re
°c
13. S
20.8
21.2
21.0
20.3
Unfi-tered 3s.~cles GF/C Filtered Samples
du--rer.ieo
Solids
aig t'
1.2-
1.30
7.50
4.39
1.96
2.05
3.37
13.53
1.1*9
2.12
7.82
4.89
1.70
2.75
7.95
7.48
I.Jo
2.1U
7-57
4.49
1.13
2.29
8.10
8.16
1.51
2.6o
8.03
5.15
1.45
2.93
6.57
9.22
Volatile
ouspendei
Solids
x£ :
o.6s
C- v£
4! 33
2.87
0.68
2.05
5.83
3.87
0.67
0.91
11.96
3.38
c.53
1.12
5.68
Ij-.O^
0.70
1.13
^.85
3.18
0.1+9
1.18
^.90
it. 76
:iitrt;-er. *3 ::
Zr :5 " i -
^, -
7~
~^
156
17C
56
50
156
13t
65
65
50
131
122
88
84
85
. P,~. 3
h^ <'
24
14
16
8
12
12
22
10
67
182
328
861
82
282
148
139
_ _ .
Fh:sr-;rus
M^ '
10
16
92
69
8
15
85
77
21
19
12
11
9
12
15
21
:::tro.;- ,-, ii
Organic
-& *
1^8
86
107
95
k6
90
60
60
62
65
58
4l
50
91
82
ko
62
12
34
<5
22
50
91
:iH3
12
21
9
2'
1L
26
y-
32
30
20
36
40
20
54
29
42
1C
2-
13
IS
1J
25
23
22
63
315
^-J1
161
33
3CC
162
177
:-.£-;;c3
-t/'
16
15
11
3
13
13
7
8
13
14
13
16
12
14
16
13
4
6
4
3
6
4
3
2
U.
13
10
11
11
13
11
8
Total
M«A'
91
120
158
151
78
135
115
72
92
87
79
60
79
117
106
114
390
193
206
96
335
223
276
Phospr.D.-us
as r
?0i
/ .
'**&/
li
1
28
21
2
9
16
26
4
8
22
14
8
6
31
20
2
5
32
13
2
4
33
9
6
6
4
3
5
5
5
5
-3tal
_ / -
Ms/'
13
20
51
32
30
18
37
43
9
10
25
16
p
"
32
23
8
10
33
23
7
10
39
16
11
11
9
6
7
11
8
7
Fe
us A
10
<1
<1
<1
2
<1
<1
<1
Cond.
(10~6)
mhos
86
87
91
87
88
90
91
90
92
88
89
92
90
88
96
92
92
88
97
91
91
pH
8.1
8.2
8.7
8.3
8.0
3.0
8.5
8.7
8.1
3.1
6.3
8.4
3.0
7.9
3.6
3.7
7.9
8.0
8.8
8.7
7.9
7.9
8.7
8.7
7.9
7-9
7-9
7.9
7.9
8.0
8.0
8.0
-------
TABLE C-3 (Continued)
Dnte
9-10
9-12
9-15
9-17
9-19
Fond
Detrntion
Time
P
d'.ys
8
Arsay
No.
ll
8
An nay
No.
d
8
A;; say
Ho.
ll
8
A.M'.ny
No.
1,
8
As: say
No.
14
Pond
No.
1
2
3
1*
5
6
7
8
l
2
3
1*
5
6
7
8
1
2
3
U
5
6
7
8
1
2
3
U
5
6
'!
8
1
2
3
14
5
6
7
8
Influent
Description
LTW
P% III
rjt in
1$ III + TE
LTW
?£ Ill
1% III
1$ III + TE
LTW
7$ III
1$ III
1% III 1- TE
LTW
e% HI
1^. Ill
1% III 1- TE
LTW
2$ III
rjt in
1# III + TE
LTW
?/. III
\.% III
1$ III + TE
LTW
fi> III
1% III
1$ III + TE
L1V
2^. Ill
lit III
L% III + TE
LTW
2% III
1^ III
1% III + TE
LTW
2# III
1^ in
1# II] + TO
Temperature
°C
19-9
20.1
17.6
16.9
17.0
Unfiltered Sample
Suspended
Solids
m^/P,
0.39
0.38
0.33
0.3'.
0.38
0.29
0.23
0.23
0.35
< l . '<"J
0.39
O.dl
0.39
0.33
0.29
O.'il
1.19
1.61
l.'lO
1.52
0.77
0.79
O.bl
0.90
1.28
1.10
I.'i8
l.'i6
o.ju
1.37
0.86
0.30
1.77
1.75
2.28
1.30
1.37
1.35
1.88
UK.
Volatile
Suspended
Solids
iw;/e
0.3lt
0.32
0.30
0.28
0.31
0.23
0.21
0.21
0.26
0.30
0.33
0.39
0.314
o.Jl
0.26
0.35
0.63
0.80
0.85
O.U8
O.dd
O.'fk
0.69
1.03
Nitrogen as N
Organic
MB A
NH3
MS A
Total
Phosphorus
MS A
GF/C Filtered Sample
Phosphorus
Nitrogen as N F _
as P
Organic
MsA
62
U6
71
i*3
58
31*
65
55
NH3
Mg/«
31
280
131*
206
1(5
289
160
139
Id.
261
12U
110
20
282
122
117
70
igd.
131*
62
60
229
99
100
10
208
96
88
26
263
6k
115
<5
192
80
80
<5
239
ill*
or,
NOS-N03
Ms/e
10
18
16
id
8
16
16
15
10
18
17
17
12
21
18
17
<1
id
10
13
l
20
10
10
12
25
10
23
11
26
15
19
10
2d
12
19
6
23
0
V
Total
MS/*
132
25'*
215
118
119
283
171*
165
P04
MgA
2
3
1*
3
3
l*
5
2
1*
3
2
1*
2
I*
5
3
2
3
3
2
2
3
3
l*
3
3
3
2
2
2
2
1
It
d
k
5
5
5
ii
li
Total
Mg/«
5
6
6
6
l*
6
5
5
5
13
6
5
7
6
5
1*
6
2d
d
l*
12
18
23
5
Fe
Mg/«
1*
2
6
ll*
<1
2
<1
6
Cond.
(io-6)
mhos
90
91*
90
91
86
91*
91
91
pH
8.1
7-9
7.9
8.0
7-9
8.0
8.0
8.0
7.9
7.9
7-9
7.9
7.8
7.9
8.0
8.0
7.5
7.9
8.1
7.2
7.8
7.8
7.2
7.5
7.6
7.9
8.0
7.7
7.7
7.7
7>
7.(>
-------
TABLE C-J (Continued)
Date
9-22
9-24
9-26
9-29
9-50
Pond
Detention
Time
0
days
8
Assay
No.
1,
8
Assay
No.
4
8
Assay
No.
k
8
Assay
No.
k
8
Assay
No.
4
Pond
No.
1
2
3
It
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
it
5
6
7
8
l
2
3
l*
5
6
7
8
1
2
3
it
5
6
7
8
Influent
Description
LTW
Sf, III
1$ III
1$ III + TE
LTW
2% III
1$ III
1$ III + TE
LTW
25t III
ijf. Ill
1$ III + TE
LTW
256 III
1$ III
Ijt III + TE
LTW
2}, III
1$ III
l
J
'<±
2
5
3
4
3
4
3
if
it
3
it
3
3
6
U
j
4
4
j
3
3
Total
MK/«
10
4
8
6
8
4
8
6
7
y
6
4
9
10
8
6
5
4
4
4
it
4
4
8
11
15
7
12
8
25
20
Fe
W,/«
Cond.
(io-6)
rahoi;
85
86
86
84
82
87
83
84
8fa
95
92
102
86
96
100
91
pH
7.8
7-7
8.1
8.1
8.0
8.0
8.1
8.1
8.0
8.1
8.0
8.1
7-7
8.2
8.3
8.1
8.0
8.2
8.1
8.0
8.1
7.8
8.1
8.0
8.0
8.0
6.0
8.0
8.1
T.9
8.0
ro
-------
TABLE C-J (Continued)
Date
10- 1
10- 2
10- 3
10- 6
10- 8
Pond.
Detention
Time
s
days
8
Assay
No.
1*
8
Assay
No.
4
a
Assay
No.
4
5
Assay
No.
5
5
Assay
No.
5
Pond
No.
1
2
3
4
5
6
7
8
1
2
3
it
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
it
5
6
7
8
1
2
3
4
5
6
7
8
Influent
Description
LTW
2jfe III
15fe III
Ijt III + TE
LTW
256 III
ijt III
15(, III + TE
LTO
2$ III
1J6 III
1% III + TE
LTW
S% III
1% III
1'Jl, UI + TE
LTO
256 III
1# III
1# III + TE
LTW
2% III
156 III
156 III + TE
LTW
236 III
lj III
15« III + TE
LTW
Zf, III
ijt III
i III + TE
LTW
2$ III
1# III
15& III -t TE
LTW
2jt III
1$ III
1?£ III + TE
Temperature
°C
16.3
15.1
lit. 6
11.8
11.2
Unfiltered Samples
Suspended
Solids
mgA
1.60
2.15
3.00
2.66
1.67
2.63
1.99
3.11
1.73
2.06
2.75
2.24
1.28
3.29
1.91
3.31
1.04
1.65
1.80
1.9^
0.91
5.82
1.38
2.46
1.72
2.28
2.70
2.61
1.32
2.00
1.04
2.77
2.23
2.40
2.88
2.82
2.09
3.16
1.85
4.1*2
Volatile
Suspended
Solids
mgA
0.89
1.03
0.96
1.16
0.59
1.4o
0.85
1.4o
0.84
0.56
0.05
0.44
3.91
0.14
0.94
0.63
0.83
1.00
0.99
0.45
0.97
0.68
1.10
0.86
1.02
1.19
l.lU
1.12
1.93
0.76
1.78
Nitrogen as N
Organic
ve.lt
99
103
170
91*
170
92
82
99
NH3
ve.lt
7
215
92
92
15
13^
101
97
Total
Phosphorus
3
5
4
4
3
5
4
4
GF/C Filtered Samples
Nitrogen as N
Organic
ve.lt
77
72
44
86
67
55
96
60
115
60
82
84
80
36
32
NH3
V&/1
20
175
86
78
22
191
86
75
25
292
80
104
4
196
118
71
<5
182
76
53
<5
287
120
94
28
225
118
119
18
227
114
92
N02-N03
MBA
10
44
24
33
10
36
24
24
5
32
20
28
2
26
18
18
11
31
24
28
10
26
24
24
22
^
31
31
20
30
29
33
Total
MB A
107
396
144
218
73
277
232
149
128
273
182
165
92
349
150
Phosphorus
as P
P04
MB A
1
2
2
2
2
<1
2
<1
4
3
2
3
3
<1
3
4
-------
TABLE C-'> (Continued)
Date
10-10
10-13
10-l'i
10-15
10-16
Pond
Detention
Time
days
5
A.-.wiy
No.
5
5
Assay
No.
5
5
Ac say
No.
5
5
As Gay
No.
5
5
A n coy
No.
5
Fond
No.
1
2
5
ii
5
6
7
8
1
2
'j
It
5
6
7
8
1
2
3
it
5
6
7
8
1
z
'j
It
5
6
7
8
1
2
3
l,
5
6
7
8
Influent
Description
LTW
rf, III
jjf. Ill
1$ III f TE
LTW
2^ III
1^ III
1% III + TE
LTW
2^ III
1# HI
1$ III + TE
LTW
2^ III
lit III
1$ III + TE
LTW
Pf, III
\$ III
1% III + TE
LTW
2$ III
1% III
1% III + TE
LTW
2$ III
1^ III
1% III + TE
LTW
2$ III
lit III
1% III + TE
LTW
2$ III
lit in
15t III + TE
LTW
2jt III
l£ III
ljt III + TE
Temperature
°C
10.8
8.0
8.8
7.U
8.7
Unfiltored Samples
Suspended
Solids
mi'./t
0.70
2.07
l.'Kl
2.00
1.07
3.^5
1.51'
2.22
2.37
3.73
'M5
U. 59
2.77
5.59
3.15
3.88
't . l'<
6.07
5.^7
h.k6
3.37
7-03
3.72
6.35
3.02
5.83
5.25
It. 26
2.67
6.67
3.61
U.Y7
U.63
7.87
1M
5.22
3.10
7.35
3.8lt
It. 81
Volatile
Suspended
Solids
mg/«
0.76
1.26
1.32
l.Ul
0.82
2.21
0.95
l.Ul
1.30
1.98
1.73
1.55
1.09
2.83
1.29
it. 03
O.ltl
5.39
5.26
2.26
0.73
U. 99
0.76
2.30
Nitrogen HS N
Organic
MS /t
NH3
MS /t
Total
Phosphorus
MS/«
OF/C Filterrd Samples
Nitrogen ac N
Organic
MS/«
250
75
82
100
75
65
75
82
NH3
VK/f-
2
292
172
12U
It
228
1U2
9
2UU
165
167
<5
287
165
156
22
292
163
129
16
288
168
139
N02-N03
M6/«
15
27
20
2-;
13
21
18
26
18
36
36
U2
27
31*
30
ItO
19
32
36
1*6
26
30
3U
Ul
Total
VK/t
277
355
283
309
IQll
386
270
278
Phosphorus
as P
P04
MS A
6
2
2
T'
',
3
2
1
3
2
2
2
2
1
2
2
It
It
It
3
it
it
3
It
Total
Mg/C
10
9
5
6
7
15
18
35
7
5
it
5
U
5
6
6
5
6
5
5
6
6
6
Fe
Mg/«
3
3
33
16
<1
2
2
16
Cond.
( 1 n 6 1
1 1U J
mhos
87
86
88
85
8lt
87
87
81t
pH
8.1
8.0
8.1
7.6
8.0
8.2
8.2
7.8
7.9
7.9
8.0
7.9
8.2
7.9
8.0
7.6
7.8
7.6
7.8
7.7
8.0
7.8
7.9
IV)
-------
TABLE C-3 (Continued)
Date
10-17
10-20
" 10-22
10-2U
10-27
Pond
Detention
Time
a
days
5
Assay
No.
5
3
Assay
No.
6
3
Assay
No.
6
3
Assay
No.
6
3
Assay
No.
6
Pond
No.
1
2
3
U
5
6
7
8
l
2
3
U
5
6
7
8
1
2
3
It
5
6
7
8
1
2
3
It
5
6
7
8
1
2
3
It
5
6
7
8
Influent
Description
LTW
2$ III
1$ III
1$ III + TE
LTW
2$ III
1$ III
1$ III + TE
LTW
2^ III
1$ III
1% III + TE
LTW
?jt III
1^ Ill
1$ III + TE
LTW
2$ III
1$ III
1# III + TE
LTW
?% Ill
1% III
i$ III + TE
LTW
2$ III
15t III
1$ III + TE
LTW
2$ III
1$ III
1% III + TE
L'lV
2% III
1$ III
1$ III + TE
LTW
Zf, III
1J6 III
1$ III + TE
Temperature
°C
7.3
7.1
10.5
11.2
9.5
Unfiltercd Samples
Suspended
Solids
mgA
3.70
6.60
5.17
It. lit
1.18
6.79
3.26
4. lit
?. in
7.01
It. 16
3.90
2.09
6.86
2.90
3.31*
3.76
9-77
5-97
h.Bo
1.75
8.76
3.13
3-32
1.52
8.82
5.1*7
U.U6
1.99
9.86
2.99
3.59
**.75
lit. 61
8.76
7.03
3.21*
15.17
6.08
6. it It
Volatile
Suspended
Solids
msA
1.18
2.30
1.85
l.Wt
0.80
2.90
1.27
1.63
0.73
2.26
l.V?
1.35
0.70
2.75
0.96
1.23
0.62
2. git
1.77
1.32
0.59
3.71*
0.96
1.21
1.07
it. 52
2.1t7
2.00
1.09
5.60
1.77
2.17
Nitrogen as N
Organic
MS A
29
Ilt6
136
58
1*8
82
110
60
NH3
MS A
22
273
112
136
38
275
iW
1U8
Total
Phosphorus
MS A
33
39
62
17
ito
31
18
GF/C Filtered Samples
Nitrogen as N
Organic
MS A
131*
130
106
103
82
3'*
62
21*
91
79
103
38
67
15
67
29
10
82
10
31
70
70
1*8
39
NH3
MS A
Il2
278
125
137
sh
251*
ll*8
127
31*
191*
61
76
U6
225
100
82
<1
177
103
89
10
lit
22
6
12
12
21
10
13
20
25
9
17
13
20
Total
MS A
196
1*33
2bl
273
122
311*
232
165
139
293
186
l"t5
126
258
187
137
20
272
2llt
231
82
288
221
231
Phosphorus
as P
P04
MS A
2
<1
2
<1
<1
1
2
1
It
3
it
6
3
it
3
3
it
3
3
3
3
2
3
3
2
2
3
it
It
5
it
10
3
3
3
2
2
2
2
1)
Total
MgA
8
6
6
lit
5
7
12
8
6
7
7
11
7
6
8
9
5
5
3
3
6
5
5
5
6
8
5
5
7
6
7
12
It
6
5
5
6
6
It
6
Fe
MgA
Cond.
(io-8)
mhos
86
87
85
87
83
86
88
86
89
92
91
91
86
96
91
91
pH
7.7
7.8
7.6
7.8
7.8
7.9
7.7
7.6
7-8
8.0
8.1
8.1
8.0
8.2
8.1
8.0
7.8
8.2
8.2
8.3
8.2
8. it
8.3
8.2
8.1
8.1
8.2
8.1
8.2
8.3
8.2
8.2
7.9
8.3
8.2
8.2
8.1
8.1*
8.2
8.2
IX)
CO
-------
TABLE c-3 (Continued)
Date
10-28
10-29
10-30
10-31
Pond
Detention
Time
days
3
Assay
No.
6
3
Assay
No.
6
3
Anoay
No.
6
3
Assay
No.
6
Pond
No.
1
2
3
4
5
6
7
8
1
2
3
it
5
6
7
B
1
2
3
)(
5
6
7
8
1
2
3
it
5
6
7
8
Influent
Description
LTW
2i6 III
1J6 III
1?S III + TE
LTW
2% III
156 III
1% III 4 TE
LTW
2% III
1J6 III
156 III + TE
LTW
2% III
1?, Ill
1% III + TE
LTW
256 III
156 III
156 III + TE
LTW
2% III
156 III
1% III + TE
LTW
256 III
1$ III
156 III + TE
LTW
256 III
156 III
156 III + TE
Temperature
°C
9-3
9.2
8.4
9.4
Unfiltered Samples
Suspended
Solids
mg//
1.70
11.96
4.87
5-33
2.30
13.75
4.71
5.54
3.43
10.27
4.77
5.13
1.63
10.67
5.22
'J.'J'J
4.25
14.05
7.72
7.30
3.30
I'l. 82
6.32
6.94
3.95
11.40
5.91
6.36
2.69
12.37
5.20
5.54
Volatile
Suspended
Solids
me//
0.58
4.20
1.83
1.76
0.82
5.65
1.71
2.03
1.00
3.54
1.43
1.79
0.59
4.38
1.86
P. 21
1.08
3.73
1.63
1.84
0.63
4.67
1.65
1.90
Nitrogen as N
Organic
MB//
32
230
60
86
46
280
74
134
NH3
MS//
5
208
108
275
17
258
153
172
Total
Phosphorus
MS//
10
10
9
14
6
11
10
9
CF/C Filtered Samples
Nitrogen as N
Organic
MB//
29
50
38
4o
16
65
38
32
NH3
MB//
38
172
96
156
39
179
114
136
4
242
126
127
2
258
127
108
NOS-N03
MB//
26
18
26
29
19
22
22
26
17
20
21
32
19
11
28
28
Total
MB//
50
312
185
199
37
334
193
168
Phosphorus
as P
PO*
MB//
3
2
3
2
3
2
2
1
6
2
2
3
2
2
2
2
Total
MB//
7
6
10
6
4
4
4
4
Fe
MB//
Cond.
mhos
pH
7.9
8.1
8.0
7.9
7.8
8.2
7.8
0.0
8.1
8.1
8.0
8.2
8.0
8.4
8.0
8.2
VO
LTW - Lake Tahoe Water.
0.1$ II - 0.1$ secondary effluent from South Tahoe Public Utility District's (STPUD) Waste Treatment Plant and 99.9!^ LTW.
Ijt II - 1.O56 secondary effluent from STPUD Waste Treatment Plant and 99.056 LTW.
1?» S-II - 1.0?» simulated (chemically) secondary effluent and 99.056 LTW (see Table A-l).
bLTW - Lake Tahoe Water.
256 III 2jt tertiary effluent from STPUD Waste Treatment Plant + 98$ LTW (tertiary effluent is collected before chlorination).
156 III - 1$ tertiary effluent from STPUD Waste Treatment Plant + 9956 LTW.
156 III + TE - 156 tertiary effluent from STPUD Waste Treatment Plant + trace elements (see Table A-l) + 99$ LTW.
°Rate of influent Lake Tahoe Water to Pilot Pond 7 vao found to be approximately 3-1/2 times the designed rate (for up to possibley 4 days), this, creating a ''washout" effect.
-------
TABLE c-4
PILOT POHD INFLUENT CHEMICAL ANALYSES
Of
Sampling
1969
7-10
7-14
7-16
7-17
7-18
7-21
7-23
7-23
7-25
7-28
7-30
7-31
8- i
8- k
8- 5
8- 6
8- 7
8- 8
8-11
8-12
8-13
8-15
8-18
8-19
8-10
8-20
3-21
8-22
8-25
3-26
8-27
8-29
9- 1
9- 2
9- 3
9- 8
9- 8
9-10
9-L2
9-15
9-17
9-19
9-19
9-22
9-21.
9-26
9-26
9-29
9-30
10- 1
10- 2
10- 3
Assay
No.
1
1
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
,
4
l<
1*
4
1+
It
4
it
It
It
it
It
tt
it
it
it
Influent
Type
STPUD IIb
SLTWC
SLTW
SLTW
SLIW
SLTW
SLTW
5TPUD II
SLTW
SLTW
SLTW
STPUD II
SLTV
SLTW
SLTV
SLTO
SLTH
SLTW
SLTV
STPUD II
SLTW
SLTV
SLTW
SLTW
STPUD II
5LIV
SLTW
SLTW
SLTV
STPUD II
SLTW
SLTW
SLTW
SLTW
SLTW
STPUD IIId
SLTW
SLTV
SLTW
SLTW
SLTW
SLTW
STPUD III
SLTW
SLTW
SLTW
STPUD III
SLTW
SLTW
SLTW
SLTV
SLTW
Uofiltered Samples
Suspended
Solids
mg/t
35.29
1.48
1.37
1.53
1.75
0,80
10.40
0.94
0.66
0.56
23.95
0.6k
0.40
0.55
0.58
0.37
0.18
0.52
50.85
0.40
0.35
0.36
0.42
6.90
0.21"
0.44
0.43
0.37
4.69
0.39
0.37
0.38
0.44
0.39
1.97
0.48
0-51
0.61
0-30
0.69
0.62
0.40
O.'w
0.54
0.57
0.52
0.52
0.92
Volatile
Suspended
Solids
mg/l
1.28
0.38
0.51
0.59
0.34
5.77
0.15
0.46
22.21
O.ltl
0.2lt
0.34
0.34
0.20
0.25
29.35
0.23
0.19
0.20
6.13
0.22
0.26
0.2-
it. 09
0.32
0.31
0.27
1.09
C'.27
0.30
0.51
0.39
0.3c'
C.26
0.28
0.24
0.48
Nitrogen as H
Organic
Mg//
1,250
68
3,200
1,280
60
4,710
I,lt62
32
62lt
122
426
98
455
383
16
NH3
Mg/i
18,1*00
lt8
16,000
20,000
31
25,240
19,620
21
23,720
18
11,627
80
11,910
12, It 90
18
Total
Phosphorus
Mg/'
10,000
13
39
8,200
12,600
13
13,itoo
7,660
7
9,700
6
152
25
Iit2
26
3
COD
ing /«
in.
76
69
25
10
Mi
29
BOD,
mg/2
20
13
12
7
2
Filtered Samples3
Nitrogen as N
Organic
M8/«
1,600
82
45
3,400
25
1,045
27
51
94
4,560
1,615
74
40
786
48
89
405
67
<>
532
32
378
58
79
NH3
Mg/<
20,250
52
7
13
77
56
l£,500
35
<5
28
16,100
25
<5
9
31
27
25,620
20
46
49
27,600
60
44
38
22,660
46
18
36
25
11, 579
62
26
20
57
18
<5
11,390
36
<5
10
14,830
15
24
14
NOs: + NO 3
Mg/«
4,000
4
3
4
7
3
6,100
11
2
6
1,300
7
4
8
15
6
270
12
6
21
3,620
8
7
15
2,730
16
19
13
5
840
7
11
14
3
18
<1
14
7
10
50
30
13
2
Total
m/«
25,850
138
_
129
_
26,000
_
30
18,445
34
-
97
127
30,460
-
_
-
32,835
-
125
93
26,176
-
_
97
119
12,824
136
_
-
65
-
-
82
-
-
15,258
105
-
95
Phosphorus as P
PO,
VK/t
7,800
8
4
9
5
3
8,160
4
3
2
11, 800
2
3
3
1
6
11,800
2
2
4
7,140
3
4
It
9,000
4
4
6
3
132
3
3
3
5
3
5
77
3
7
5
50
11
2
3
Total
MgA
8,200
43
16
12
3
8,4oo
17
4
13
12,240
4
5
57
27
25
12,400
5
2
37
7,660
6
8
13
9,500
5
21
7
7
146
6
it
6
10
118
22
8
5
62
17
15
5
Ca
mg/2
26.6
30.8
30.0
33.6
38.8
32.2
46.2
74.2
64.6
Cl
me/8
26.9
27.0
28.1
22.0
24.6
25.4
23.3
26.4
22.4
Fe
Mg/«
41
<1
58
2
58
16
<1
6
28
8
7
6
19
li
50
PH
7.8
7-6
7.8
7.8
7.8
7-7
7.6
8.1
7.7
7.4
7.7
7.8
7.6
7.8
7.9
8.0
8.0
8.1
7.9
8.0
8.0
7.9
8.0
7-5
7.8
7.9
8.2
7.9
7.9
7.6
7.7
8.0
8.0
7.4
7.6
7.9
7.9
7.7
7.4
Alt.
as
CaC03
mg/i
159.5
174.0
1S*.7
176.5
188.0
203.8
255.2
238.0
Cond.
(lo-s)
mhos
501
103
93
92
96
480
90
94
118
500
92
485
90
91
535
90
89
500
86
88
560
83
570
88
-------
TABLE C-4 (Continued)
Date
of
Sampling
10- 3
10- 6
10- 8
10- 8
10-10
10-13
10-13
10-lli
10-15
10-16
10-17
10-17
10-20
10-20
10-22
10-24
10-24
10-27
10-27
10-28
10-29
10-30
10-J1
Assay
No. '
5
5
5
5
5
5
5
5
5
5
5
6
6
5
6
6
6
6
6
6
6
6
6
Influent
Type
STPUD III
SLTW
SLTW
STPUD III
SLTU
SLTtf
STPUD III
SLTW
SLTW
SLTW
SLTW
STPUD III
SLIW
STPUD III
SLTH
SLIW
STPUD III
SLTW
STPUD III
SLTW
SLTW
SLTW
SLTW
Unflltered Samples
Suspended
Solids
us/I
0.94
O.ol
9.6ae
l.llt
0.86
2.66
0.98
0.58
1-23
0.64
0.52
3.89
1.00
0.77
1.10
0.54
0.72
1.47
0.77
1.33
0.87
0.83
Volatile
Suspended
Solids
mg/J
0.81.
0.23
0.9lt
0.68
0.39
1.06
0.28
0.52
0.8}
0.89
0.26
0.42
0.22
1.28
0.32
0.50
0.20
Nitrogen as N
Organic
MS/*
,89
527
297
1.8
411
310
489
278
32
NH3
ve/t
12,200
16,990
22,000
20
15,71*0
18,800
15,590
16,020
10
Total
Phosphorus
MgA
33<
160
7
134
392
157
153
6
COD
"g/i
10
20
31
31
60
58
BOD5
mg/l
<1
<1
4
10
Filtered Samples
Nitrogen as N
Organic
ug/'
522
60
479
77
383
41
503
<5
169
627
20
474
26
HH3
Mil
9,810
6
20
13,880
<5
l>
19,620
50
38
15,310
18
18, 770
<5
9
16,840
<5
15,780
27
<5
S02 + NO 3
Vf.lt
1DO
21
a>
630
15
35
433
24
13
215
23
120
13
6
60
12
140
25
22
Total
Mg/f
10,792
37
_
14,989
_
116
20,436
-
92
16,028
44
19,050
_
_
17,527
34
16,394
-
50
Phosphorus 33 ?
F0«
m/.'
tl
2
5
295
2
2
146
U
3
104
1;
361,
3
2
148
it
110
3
2
Total
-/''
-a
57
5
297
13
150
13
6
1*4
's
>09
10
5
163
5
151
11
^
=* '
~ " 2
38."
^2.:
- ^
6^.5
Cl
=«/'
20.7
26.4
26. i.
3J. 3
29.5
7e
-t /
i;
9
;
^
<1
p3
8. 1
7.1
7
8.2
3.0
7.6
7.7
7-"
6.2
8.C
7.5
a'.2
a.:
3.C
3.2
S.I
-,,
".9
Alk.
as
CaC03
B3/<
2-,' j . 2
198.0
282.5
2=3.3
231.5
258.2
Cond
(io-s)
^hos
-5o
-70
83
^50
05
6 1C
5T5
36
525
effluent fron South Tahoe Public Utility District's (STPUD) Waste Treatment Plant was passed through 0.1*5 ^ Millipore filters. Shore-l^Jce Tahoe V2t°
was passed through '3F/C filters.
bSTPUD II - South Tahoe Public Utility District's Waste Treatment Plant's secondary (II) effluent.
^SLTW - Shore-lake Tahoe Water pumped to the pilot ponds through 2,000 ft of 2 in. PVC pipe from a location near the U. S. Coast Guard Pier.
STPUD III - South Tahoe Public Utility District's (STPUD) Waste Treatment Plant's tertiary (III) effluent before chlorination.
Stormy day.
-------
TABLE C-5
BIOMASS MEASUREMENTS
TABUS C-5 (Continued)
Date
1968
June 28
[Assay
Started
June 12]
June 30
July 2
July 8
[Assay
Started
July 5)
July 10
July 12
July 15
July 17
July 19
July 22
Assay No.
(9)
2
(10 daya)
n
"
|'
||
ii
11
|'
"
3
(5 days)
"
"
»
ii
i'
'
ii
H
3
(5 days)
"
"
"
n
ii
n
ii
"
"
Pond
Ho.
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
8
1
2
4
5
6
7
8
1
2
3
4
5
(,
7
8
1
2
5
4
5
r,
7
u
i
2
3
4
5
6
7
8
Suspended
Solids
mg/1
2.00
2.24
3-39
4.74
2.53
2.58
6.85
5.28
3.01
2.87
5-07
4.83
2.76
3-12
6.46
5.44
2.314
2.59
6.90
5-97
2.56
3.09
6.88
5.13
0.90
0.48
0.94
0.87
0.88
0.88
0.80
0.78
0.60
0.70
0.73
0.67
0.69
0.68
0.68
0,6:5
0.59
0.89
1.49
1.34
1.21
1.29
1.13
1-13
0.85
1-75
2-33
2.09
1.76
1.83
2.20
l.faY
0.71
l.YU
2 . 'jO
3.00
1-77
l.Bi
i'.l.'j
2 . i::
0.48
1.74
5.65
3.30
1.20
1 . >
,','la
'-''' lj
2. OS
1.48
6.14
4.05
1.20
l.'li
3-93
2.68
Volatile
Suspended
Solids
mg//
0.91
0.94
1.43
1.95
0.90
0.86
2.85
2.06
0.81
0.93
1.70
0.79
1.04
1.32
2.70
2.4}
0.93
0.68
2.17
2.04
0.84
1.08
2.77
2.01
0.54
0.53
0.83
0.84
0.53
0.46
0.60
0.38
0.22
0.29
0.27
0.22
0.14
0.22
0.15
0.13
0.31
0.4l
0.77
0.61
0.42
0.45
0.60
0.18
0.33
0.61
1.06
1.01
0.61
0,64
1.03
0.91
O.L'L'
0.1.1,
1.01
1.20
0.40
a.yj
0.90
0.1,3
0.21
0.46
i . y,
i.fii
0.06
0.50
i.ji.
1.09
o.4o
0.46
2.57
1.84
0.25
0.35
1.33
1.04
Date
1968
July 24
July 26
July 29
Aug 5
[Assay
Started
Aug 2]
Aug 7
Aug 9
Aug 12
Aug IJ
Aug 14
Aug 15
Assay No.
(9)
3
( 5 days )
|'
"
"
"
"
"
"
"
11
11
11
"
4
(3 days)
"
11
,.
"
11
11
"
11
4
(3 daya)
"
"
"
"
"
"
"
"
"
"
«
"
"
"
Pond
No.
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
a
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
4
5
6
7
8
1
2
3
4
5
r.
7
8
1
2
3
4
5
l>
Y
8
1
2
3
4
5
6
7
8
Suspended
Solids
mg/J!
1.61
1.94
10.97
4.59
1.96
2.77
9-78
5.18
1.62
1.53
6.83
4.27
1.00
1.30
4.16
2.98
0.76
1.21
5.04
4.51
0.84
1.46
3.61
2.90
0.52
0.50
0.50
0.35
0.59
0.67
0.69
0-57
0.63
0.63
0.74
0.67
0.66
0.70
0.53
0.65
0.64
0.66
0.62
0-79
0.75
0.72
0.68
0.65
0.60
0.79
1.52
1-77
3.20
3.02
2.65
5.07
2.64
4. a",
4.70"
_
2.71
2.72
2.91
2.56
11.91.
I4.9L'
4 .09
_
2.69
2.74
2.85
2.57
2.78
5.13
>>»
Volatile
Suspended
Solids
i»g/J!
0.41
0.81
4.40
2.15
0.47
0.62
2.91
1.71
0.53
0.86
3-19
2.40
0.33
0.41
1.41
1.07
0.23
0.50
2.21
2.52
0.26
0.48
1.25
1.13
_
0.26
0.23
0.2k
0.27
0.30
0.31
0.32
0.33
0.30
0.33
0.34
0.35
0.47
0.44
0.25
0.30
0.30
0.26
0.37
1.03
1.27
_
0.(,2
O.Y2
0.78
0.71
O.dl.
2.L",
2 . 56"
_
0.82
0.93
1.15
0.78
1.01
2.9;'
1.8G
1.07
1.10
1.32
0.77
1.09
3.08
2.67
132
-------
TABLE c -5 (Continued)
TABLE C-5 (Continue'])
Date
1968
Aug 21
(Assay
Started
Aug 16]
Aug 23
Aug 26
Aug 27
Aug 28
Aug 29
Aug 30
Sept 6
(Assay
Started
Sept 1]
Sept 9
Sept 11
Ar,nay No.
5
(5 days)
"
"
"
"
"
"
"
"
"
"
"
"
"
"
"
"
"
"
5
(5 days )
"
"
"
"
"
"
"
11
"
"
6
(10 days
"
"
"
"
"
"
"
"
"
"
11
"
"
..
"
"
"
"
"
"
"
Pond
NCI.
1
2
4
5
6
7
8
1
',
4
5
6
7
8
1
2
3
4
5
h
7
8
1
2
3
li
5
6
7
8
1
2
3
5
6
7
8
1
2
^
ii
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
Sunnen'lorl
Gnllnn
3-55
2.93
2-55
2.64
2.62
2.95
:'.;"!
') . i ",
2 . Vi
1.67
1.60
l.'lf,
1.93
-
] .4(1
5 .f.n
3-2^
1.09
1.05
2-35
2.18
1.87
4.25
5-77
1.54
1 .C^J
2.49
2.23
1.51
3-79
3.43
1.21
1.27
1.98
1.95
-
1.47
3.89
3.4o
1.20
1-27
1.90
1.93
1.38
3.64
2-93
1.12
1.15
1-93
1.94
0.55
0-95
0.88
0.89
0.77
0.87
0.82
0.79
0.39
0-59
0.54
0.57
0.49
0.61
0.61
0.63
0.72
0.94
0.99
0.95
0.76
0.97
1.69
1.56
Volotll»
Sun ponded
SnlMn
mit/t
.
1.64
2.23
1.56
1.25
1-59
1.47
1.44
1 . ',11
; .i'l
1.1.1,
0.77
0.79
1.20
0.97
_
0.78
2.f,0
2.37
0.51
0.4r>
1.49
1.19
-
0.90
3-02
2-55
0.59
0.62
1-53
1.53
_
0.83
5-5}
2.71
0.60
0.61
1.48
1.42
-
0.74
2.84
2.35
0.46
0.51
1.26
1.22
-
0.84
3-23
2.29
0.58
0.62
1.58
1.53
0.33
0.47
0.47
0.46
0.37
0.44
0.44
0.46
0.30
0.40
0.59
0.40
0.33
0.38
0.43
0.48
0.44
0.50
0.63
0.60
0.46
0.61
1.50
1.28
DnLc
1968
Gcpt 13
Sept 16
Sept 18
Sept 20
Sept 23
Sept 25
Sept 27
Sept 30
Oct 1
Dot 2
Au nay No.
(o)
(i
(10 days)
"
ii
"
M
11
11
"
11
11
"
11
n
11
"
"
"
11
"
»
"
11
"
"
"
"
"
6
(10 days)
"
"
11
"
||
"
11
"
11
"
"
"
11
11
"
"
"
"
"
"
»
"
"
"
"
"
"
"
Pond
No.
1
S
Ii
5
6
7
8
1
,
1,
5
6
7
8
1
?
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
li
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
1
8
1
2
3
4
5
6
7
8
W4
o.««
0.95
1.12
1.03
0.72
0.86
4.22
1.70
D.H',
i -u)
0.70
1.58
6.00
2.04
1.06
1.51
0-90
1.7'.
7.46
4.84
3-13
1.39
2.08
1-79
2.4I|
6^36
4.68
2.75
1.4(i
1.72
1-52
1.16
1.98
4.10
3.53
2.04
1.47
1.85
1.63
1.30
2.14
4.63
4.03
2.46
1.28
1.52
1.70
1.19
2.00
4.69
3.64
2.70
I.JO
1.70
1.6-,
1.23
1.81
4.50
3-55
2.14
0-99
1.32
1.25
0.94
1-36
3-52
2.48
2.59
1.18
1.61
i.4o
1.10
1.66
4.20
3.22
Volatile
fi. Ill:'
O.'/i
O.liY
O.Yf,
0.6'',
0.39
o.f,i
3.30
3.10
1.T7
(>. Ill
O.y
0.77
0.36
1.01
fi.'iY
5-3'.
1.91
0.51
1.01
O.B7
0.48
1-35
5-9^
4.1.0
2.fJ.
0.i'2
1.27
1.12
O.*il
1.64
3.84
2.29
0.63
0.91,
0.79
0.35
1.27
2.74
2.15
2.06
0.69
1.16
1.07
0.57
1.62
3.44
3-36
2.14
0.56
0.97
1.00
0.51
1.29
5.42
5.06
1.81
0-39
0.83
0.76
0.30
0.81
2.56
1.99
2.15
0.47
1.04
0-95
0.46
0.97
2.79
2.45
133
-------
TABLE C-5 (Continued)
TABLE 0-5 (Continued)
Date
1963
Oct 3
Oct 4
Oct 9
[Assay
Started
Oct It]
Oct 11
Oct 15
Oct 18
Oct 21
Oct 23
Oct 25
Oct 28
Assay No.
(el
6
(10 days)
"
"
"
"
"
"
7
(5 days)
"
"
"
"
11
"
11
"
"
"
11
7
(5 dayB)
"
"
"
"
"
"
"
"
"
"
"
11
''
"
"
"
»
"
"
Bo.
1
2
3
4
5
6
7
8
1
2
3
It
5
6
7
8
1
2
3
It
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
It
5
6
7
8
1
2
3
It
5
6
7
8
1
2
3
It
5
6
7
8
1
2
3
4
5
r,
7
8
1
2
3
It
5
6
7
8
1
2
3
It
5
6
7
8
Suspended
Solids
mg/l
2.56
1.16
1.77
1.61
1.15
1.77
3-91
3-36
2.84
0.93
1.61
1.30
0.96
1-57
3-76
3.34
0.52
0.88
1.17
0.93
0.76
0.86
2.15
4.45
0.60
0.93
1.20
1.06
0.93
1.29
it. 02
It. 28
3.61
3-77
It. 89
It. lit
"t.13
It. 17
It. 72
6.01
2.71
2.65
3.07
2.71
2.57
2.61
5.39
5.39
2.1(7
2. Ill
2.50
2.12
2.20
2.36
6.113
7.29
2. lit
2.20
2.12
l.fUl
1.90
2.10
7.82
9- 91s
1.69
1-79
1.76
1.}''
1.1(8
1.68
8.21
11.03
l.H
1.61|
I."i5
l.Oll
0.98
1.69
7-32
10.00
Volatile
Suspended
Solids
mg/t
2.34
0.60
1.16
1.02
0.59
1.15
2.76
2.15
2.52
0.1(6
1.12
0.96
O.ll2
0.95
2.70
2.5ll
0.35
0.1(2
0.72
0.62
0.33
0.27
1.75
2.76
0.23
0.36
0.6li
0.1)7
0.32
0.57
2.2l(
2.52
1.16
0.99
1-25
1.11
0.94
1.21
2.92 -
2.90
0.67
0.73
0.98
0.91
0.71
0.76
2.81
2.88
0.72
0.73
0.78
0.75
0.57
0.78
5-23
3-77
0.511
0.65
0.67
0.6',
O.llf,
0.78
3.80
5.06"
0.50
0.63
0.72
0.59
o.it7
0.73
It.ltS
5.75
O.liO
0.61t
0.65
0.55
0.39
0.69
4.33
5-38
Bete
1968
Oct 29
Oct 31
Nov 1
Assay No.
(9)
7
(5 days)
-------
TABLE C-6
SIMULTATED SECONDARY EFFLUENT FEED FOR PILOT PONDS
MACRONUTRIENTS
NH4 Cl
K2 HP04
Fe S04 TH20
Mg S04 ?H20
MICRONUTRIENTS
Co(N03)2 6H20 ,
(NH4)5 MoY024 4H20
Cu S04 5H20
Zn Acetate
Mn Ci2
CONCENTRATION IN FEED
76. k
56.0
2.^8
53-2
0.012
0.122
0.200
0.280
0.500
5.000
IRON AND TRACE ELEMENTS SUPPLEMENT FOR
TERTIARY EFFLUENT FEED FOR PILOT PONDS
MACRONUTRIENTS
Fe S04 7H20
CONCENTRATION IN FEED
(nig/-O
2.U8
MICROFUTRIENTS
Co(N03)2 6H20
(NH4)6 Mo7024
Cu S04 5H20
Zn Acetate
Mn C12
0.012
0.122
0.200
0.280
0.500
5.000
135
-------
TABLE D-l
CHEMICAL ANALYSES OF SHORE AND MID-LAKE TAHOE
Dnte
1967
6- 4
8-23
1968
7-15
9-1}
9-13
10- 4
10- 4
11- 8
11- 8
12-12
12-12
1- 3
1- 4
2- 4
2- 4
5- 6
5-15
4- 1
5- 6
5- 6
6- 4
6- 9
7- 1
7- 1
8- 5
8- 5
9-10
9-10
10- 6
10- 6
11- 4
11- 6
12-12
12-14
1970
1- 6
1-12
1-16
2- 4
2- 6
2- 9
3- 9
3-12
5-12
3-25
3-30
4- 9
4-20
4-22
5- 6
5- 6
5-11
5-14
5-21
6- l
6- 1
6- 2
6-10
6-19
6-23
6-29
6-29
7- 7
7-20
7-21
8- 4
8- 4
8-26
8-26
9-29
9-29
10-15
11- 2
11- 2
11-2}
11-2}
Sample
Location
MLT8
MLT
MLT
MLT
SLTb
MLT
SLT
MLT
SLT
MLT
SLT
MLT
SLT
MLT
ELT
SLT
MLT
SLT
MLT
SLT
GLT
MLT
MLT
SLT
MLT
SLT
MLT
SLT
MLT
SLT
MLT
SLT
SLT
MLT
SLT
MLT
SLT
SLT
MLT
SLT
SLT
SLT
MLT
SLT
SLT
SLT
MLT
SLT
SLT
SLT
MLT
SLT
SLT
SLT
SLT
MLT
SLT
SLT
SLT
SLT
MLT
SLT
SLT
SLT
SLT
SLT
MLT
MLT
SLT
MLT
SLT
MLT
MLT
SLT
MLT
SLT
Unflltered Samples
Suap.
Solids
mg/(
-
33.06
-
-
3.37
0.31
_
1.20
1.41
0.62
_
0.74
_
0.80
14.78
2.83
0.53
0.53
1.31
0.60
0.98
O.l4
_
0.74
0.88
5-5}
1.07
0.10
0.29
0.61
0.18
0.37
-
0.24
0.4o
0.21
2.76
Vol.
Suop.
Solids
ag/l
-
4.72
-
0.31
_
0.4o
0.50
0.46
_
0.51
0.58
2.20
0.66
0.45
_
0.42
0.39
0.36
0.64
0.11
_
0.65
0.70
1.09
0.51
0.10
0.20
0.22
0.18
0.30
-
0.21
0.26
0.21
0.76
COD
"8/1
-
<1
<1
<1
<1
<1
l4c
11°
-
-
21
<1
-
6
4
-
0.7
4.8
2.8
0.4
4.5
_
2.0
_
0.4
9.1
0.45 u Mllllpore Filtered Samples
Nitrogen as N
Organic
US/1
20
107
95
61
29
175
125
225
325
150
200
<5
75
<5
56
87
86
82
40
75
60
75
3lt
30
162
198
130
165
125
132
98
244
84
<5
74
Jlf
457
192
118
58
98
106
82
38
82
50
22
106
14
142
79
110
50
91
187
94
130
77
142
211
67
82
89
41
100
192
112
103
38
121
111
50
4}4
35
68
25
NH,
M8/<
<5
15
60
63
45
48
29
34
41
20
<5
20
50
9
20
13
32
62
16
<*)
<5
<5
10
15
25
30
36
30
5
26
16
30
10
40
8
20
201
32
118
42
30
16
22
9
23
25
6
12
34
40
19
10
4
30
41
49
44
22
58
44
86
61
6
106
20
58
68
62
52
51
It2
35
34
35
62
67
NGj
M8/(
3
1
1
<1
<1
<1
<1
<1
<1
2
3
6
5
6
5
<1
<1
8
3
3
3
6
6
5
2
1
2
2
2
3
6
6
4
3
2
11
3
1
4
3
1
<1
1
1
1
3
6
7
2
4
3
3
2
5
2
}
2
2
7
<^1
4
2
2
2
-------
TABLE D-2
MAXIMUM GROWTH BATES AND MAXIMUM CELL CONCENTRATIONS ATTAINED AT
THE END OF FIVE DAYS IN FLASK CULTURE OF LAKE TAHOE WATER
Sampling
6- 6-6ya
10-16-67
10-31-67
11-14-67
12-11-67
12-12-67
1-23-68
2- 6-68
2- 7-68
2-19-68
3- 5-68
3-30-68
4- 1-68
4- 2-68
4- 4-68
4- 5-68
4-13-68
4-17-68
4-18-68
6-15-68
7-15-68
8- 9-68
9-13-68
10- 4-68
11- 8-68
12- 3-68
1- 3-69
2- 4-69
2- 6-69
3-15-69
4- 1-69
5- 6-69
6- 4-69
6- 9-69
7- l-69v
7- 1-69^
8- 5-69
9-10-69
10- 6-69=
11- 6-69
12-12-69
12-14-69
1-12-70
2- 6-70
2- 9-70
3- 9-70
3-12-70
5- 5-70
5-21-70
6- 1-70
6- 2-70
6-29-70
7- 7-70
8- 4-70
B-ffJ-yu
iJ-liij-'IO
10-15-70
11- 2-70
11-23-70
Maximum Growth Rate
(ub, day'1)
Mid-Lake
Sample
0.428
0.510
0.550
0.512
0.330
0.350
0.796
0.270
0.203
0.470
0.227
0.205
o.4o6
0.069
0.055
0.386
0.348
0.579
-
0.217
0.188
0.329
0.356
0.053
0.304
0.285
0.068
0.256
o.lVf
0.165
0.265
0.171
Near
Shore
Sample
0.05a
0.17
0.22
0.17
0.21
0.38
0.22
0.27
0.35
0.24
0.26
0.32
0.46
0.46
0.43
0.42
0.4-1
0.56
0.47
0.454
0.302
0.324
0.634
0.562
0.368
0.372
0.633
0.379
0.517
0.640
0.444
0.446
0.135
0.209
0.363
0.249
0.571
0.236
0.242
0.224
0.337
0.328
0.136
0.177
0.151
0.323
0.211
0.289
o.;'6o
u . L5 ;
o . 127
0.246
Maximum Growth Rate
<&W» ^'^
Mid-Lake
Sample
0.278
0.293
0.293
0.378
0.049
0.199
0.548
O.l4o
0.149
0.361
0.119
0.070
0.279
0.046
0.043
0.262
0.192
0.310
0.168
0.130
0.305
0.227
0.264
0.216
0.053
0.192
0.1()6
0.052
0.152
0.006
Near
Shore
Sample
0.255
0.223
0.336
0.247
0.207
0.231
0.360
0.318
0.349
0.350
0.220
0.290
0.116
0.110
0.153
0.175
0.349
0.160
0.168
0.169
0.283
0.214
0.114
0.066
0.087
0.221
0.11(0
0.201
o..U)5
O.ii'L
0.085
0.017
Maximum Cell
Concentration
(Xs, cellu/.iu.i3)
Mid-Lake
Sample
274.8
194.2
168.2
230.4
62.4
119.8
168.6
69.0
54.4
185.2
_
96.4
69.2
129.4
65.8
61.5
219.3
99.5
203.4
133.4
121.0
178.0
157.3
65-9
164.5
177.1
70.0
126.5
JO'i.5
57.!-'
120 . o
56.7
Near
Shore
Sample
128
108
79
48
73
13
95
96
80
199
201
161
294
259
206
210
304
271
255. "*
151.6
195.6
126.0
144.2
37.8
104.0
147.6
162.6
181.8
223.0
102.6
133.7
90.0
97.5
136.1
102.3
263.9
201.1
139.7
129.0
149.7
156.2
120.1
79.5
79.1
150.9
92.3
144.5
Hi1.';
1 '*!.<>
' A< . 5
59-6
Selenastrum gracile used as test organism.
Selenaatrum eapricornutum substituted for S._ graeile at this sampling date.
Sample date 10-6-69 cultures were seeded with Chlorella contaminated S. eapricornutum.
138
-------
TABLE D-3
CREEK WATER ANALYSES
Date
i2fl
5-20
6-17
7-19
8-27
LS-12
1968
1-20
2-24
6-19
6-21.
8-23
9- 3
9- 4
10- 3
n- k
12- 3
1969
1- 3
2- It
3- 4
It- 1
5- 6
6- k
7- 1
8- 5
8- 8
9-10
10- 2
11- 4
12- It
Creek
Name
Ward6
Incline
Ward
Incline
Ward
Ward
Incline
Incline
TT. Tr.a
Tr. Tr.
Tr. Tr.
Ward
Incline
Tr. Tr.
Ward
Incline
Ward
Incline
Tr. Tr.
Ward
Incline
Tr. Tr.
Ward
Incline
Tr. Tr.
Ward *
Incline^
Tr. Tr?
Ward
Incline.
Tr. Tr?
Ward
Incline.
Tr. Tr?
Ward
Incline
Tr. Tr.
Vard
Incline
Tr. Tr.
Ward
Incline
Tr. Tr.
Ward
Incline
Tr. Tr.
Ward
Incline
Tr. Tr.d
Incline if
Incline B
Incline 0
Ward
Incline
Tr. Tr.
Ward
Incline
Tr. Tr.
Ward
Incline
Tr. Tr.
Ward
Incline
Tr. Tr.
Unfiltered Sample B
Susp.
Solids
HB/a
1.62
72.05
1*6.85
0.68
3lt.olt
2.22
0.1*2
21.85
2.01*
0.66
7-55
2.66
18.06
13. 40
Vol.
Susp.
Solids
ng//
0.85
ll*. Jl*
9.60
0.6k
10.23
1.50
0.1*2
!*.50
1.26
0.53
1.87
2.11
5.13
i*.79
COD
n«/<
10
15
10
23
10
15
1*5
52
1
8
20
k
<1
-------
"TABLE D-3 (Continued)
Date
1)70
1- 5
1-58
2-10
i-23
11-29
5-11*
5-25
6- i*
6-16
6-23
7- 1
7-14
7-30
8- 7
8-14
8-27
9- 2
9-17
9-23
10- 1
10- 7
Crees
-lane
Ward
Incline
Tr, Tr.
Ward
Incline
Tr. Jr.
Ward
Incline
Tr. Tr.
Ward
Incline
Tr. Tr.
Ward
Incline
Tr. Tr.
Incline A
Incline B
Incline 0
Ward
Incline
Tr. Tr.
Ward
Incline
Tr. Tr.
Ward
Incline
Tr. Tr.
Ward
Incline
Tr. Tr.
Ward
Incline
Tr. Tr.
Ward
Incline
Tr. Tr.
General8
Ward
Incline
Tr. Tr.
General
Ward
Incline
Tr. Tr.
General
Ward
Incline
Tr. Tr.
General
Ward
Incline
Tr. Tr.
General
Ward
Incline
Tr. Tr.
General
Ward
Incline
Tr. Tr.
General
Ward
Inc line
Tr. Tr.
General
Ward
Incline
Tr. Tr.
General
Ward
Incline
Tr. Tr.
General
Unfilterri Samples
Susp .
Solids
=en
0 . 37
S6.3<.
2.21
1.91
11. Mi
2.12
4 . 4o
8.20
5.22
2.62
IB. 11
3.17
1.62
6.79
3.49
1.55
7.18
3.29
1.15
91.J2
5.03
0.64
26.71
3. 68
0.35
0.36
58.30
2.1*9
0.53
2.33
16.30
3.01
1.70
0.80
26.97
4.28
0.38
0.55
21.57
4.34
0.31*
0.75
21.65
4.76
0.61
0.51
27.76
2.22
0.28
1.02
9.17
1.69
0.44
O.U3
10.96
1.52
0.29
1.02
10.78
1.85
0.1*9
Vol.
Susp.
Solids
mg/f
C.25
5.05
c.88
1.02
2.77
0.53
1.23
2.32
1.1*1
0.95
3.32
0.90
0.53
1.1*2
1.13
0.57
2.23
1.1*6
0.1*9
25.28
1.26
0.36
7.61*
2.07
0.32
0.18
15.00
0.91
0.28
0.55
3.67
1.51
0.85
0.1*0
"*.17
2.09
0.36
0.25
l*.l*6
1.57
0.21*
0.32
l*.l*9
1.63
0.1*3
0.31
5.1*6
0.73
0.19
0.53
2.1*1*
1.00
0.31*
0.35
2.98
0.62
0.21*
0.1*3
2.27
0.56
0.31
TOD
n«//
2.3
2.4
23.2
<*.3
5.8
<0.1
1.6
8.1*
2.8
8.5
5.1*
20.8
0.8
5.8
22.7
"*.o
7.9
3.9
2.8
3.2
2.5
5.6
6.9
10.1
4.9
5.1*
6.8
7.8
5.4
5.5
2.1
5.8
3.1
<0.1
7.8
4.2
5.5
<0.1
7.3
3.6
<0.1
3.2
6.9
4.9
5.7
0.8
3.7
1.6
1.6
0.45 a Milllpore Filtered Samples
Nitrogen as ?!
Organic
05 ii
45
,'52
57
162
1*1*8
361*
9"*
586
380
53
500
211
25
170
125
139
151
177
139
208
191*
118
390
304
156
184
211
74
34
130
56
325
142
33
70
130
70
84
258
178
53
100
134
l6o
89
62
280
218
17
-------
TABLE D-5 (Continued)
Date
10-11*
10-22
10-28
11- 3
11-11
11-18
11-21*
12-15
Creek
Name
Werd
Incline
Tr. Tr.
General
Ward
Incline
Tr. Tr.
General
Ward
Incline
Tr. Tr.
General
Ward
Incline
Tr. Tr.
General
Ward
Incline
Tr. Tr.
General
Ward
Incline
Tr. Tr.
General
Ward
Incline
Tr. Tr.
General
Ward
Incline
Tr. Tr.
General
Unfiltered Samples
Susp.
Solids
mg/J
0.50
5.68
2.50
0.27
0.6U
3.89
2.21
0.35
3.1*3
16.75
1.55
0.21*
0.57
It. 27
1.52
1.1*0
0.51
8.1*2
I*. 71
0.55
0.1*6
1*.17
2.11
0.514
0.61
18.91
14.62
0.65
0.51
1..85
Vol.
Susp.
mgtf
0.50
1.52
0.76
0.27
0.29
l.Olt
0.80
0.22
1.35
5.72
0.52
0.25
0.30
1.13
0.52
0.97
0.35
l.Oit
1.16
0.31
0.1*0
1.28
0.80
0.1*9
0.51*
i*.50
2.60
0.63
1.19
1.65
COD
mg /
1.2
It.o
"4.9
2.9
3-2
3.2
It. 8
5.6
£ . -
.-
U.I
5-2
2.C
6.U
5.2
It.C
-------
TABLE D-4
MAXIMUM GROWTH RATES, jl, fL , AND MAXIMUM CELL CONCENTRATIONS, X5, FLASK ASSAY OF CREEK WATERS
Sampling
Date
1968
5^T9a
6-24
8-2J
9- 3
9- 14.
10- 3
11- it
12- 3
1969
1- 3
2- 4
3- 4
1*- 1
5- 6
6- it
7- l.
8- 5b
8- 8C
8- 8d
8- 8e
9-10
10- 2
11- 6
12-14
1970
1-28
2- 6
2-23
4-29
5-25
6- It
7- 1
7-1'.
7-30
B- Y
8-l't
8-27
9- 2
9-2;
10- 1
10- 7
10-14
10-22
10-28
11- 3
11-11
11-18
11-23
12- 9
12-15
Source of Sample
Ward Creek
Mb
day'1
0.318
-
0.512
-
0.192
0.926
0.536
0.395
0.649
0.701
0.606
0.470
0.513
0.451
0.567
0.635
0.736
0.468
0.280
0.332
0.606
0.302
0.131
0.350
0.1*50
0.173
O.P85
o.yu.
0.381
0.224
0.3?8
0.224
0.177
0.201
0.186
0.424
0.312
0.450
0.370
0.159
0.194
0.134
%i
day'1
-
0.166
0.329
0.039
0.432
0.336
0.289
0.463
0.335
0.377
0.254
0.246
0.255
0.292
0.371
0.451
0.410
0.190
0.221
0.1(13
0.222
O.OS'l
0.228
0.255
0.081
O.P13
o.f'iT
.
0.302
0.103
0.168
O.l'iS
0.102
0.117
0.079
0.288
0.222
0.238
0.205
0.126
0.172
0.110
X5
cells /mm3
155- U
209.8
57.2
290.6
92.0
155.0
181.2
189.6
162.0
185.8
107.8
127.0
236.5
315.9
282.4
273.7
15
0.355
0.247
O.lf'l
0.187
0.104
0.113
0.470
0.179
o.44o
0.327
0.384
0.169
0.6l4
Obi
day'1
0.322
0.432
0.336
0.432
0.519
0.451
0.683
0.343
0.264
0.277
0.447
0.299
0.107
0.377
0.495
0.337
0.162
0.162
0.305
0.286
0.049
0.222
0.246
0.250
0.366
o.rtp
O.IY'j
0.!'33
0.128
0.135
0.102
0.085
0.058
0.061
0.303
0.144
0.233
0.150
0.161
0.075
0.348
X5
cells /mm3
330.2
433-6
200.0
334.2
153.2
365.2
1072.0
264.6
l4o.4
249.8
242.2
156.2
103.0
524.8
411.4
220.8
155.0
155.0
204.2
364.2
108.6
143.1
185.1
262.9
234.0
lHB.<)
1.U).')
1P9. 3
162.3
72.7
147.2
69.7
93.1
103.7
146.0
82.9
178.7
119.2
107.3
72.1
"*03.5,
General Creek
A
Mb
day'1
-
-
-
0.417
O.p6i
o.ii07
O.J'.l'i
0.165
0.563
o.;>63
0.194
O.l'lO
0.258
0.589
0.385
0.240
0.391*
0.402
0.164
0.493
Vbt
day"1
-
-
-
0.27't
O.TfO
o.rvr
0.!'L)0
0,114
0.276
0.231
0.102
0.087
0.103
0.367
0.292
0.136
0.198
0.176
0.123
0.286
*5
cells /mm3
-
-
-
-
154.1
115.6
1'|)|.4
ivj/j
7'+.4
110.4
164.3
81.1
79.2
110.5
202.9
155.7
128.3
119.9
108.9
87.6
171.9
Selenastrum gracile used as a test organism
Selenastrum capricornutum substituted for £^_ gracile at this sampling point
'"Sample collected above Incline Village in undisturbed area
Sample collected below construction zone in Incline Village
eSample collected below golf course (50 yd above Highway 28)
-------
TABLE E-l
BURTON CREEK ANALYSES
Date
1/7/70
1/28
2/10
2/23
4/29
5/25
6/30
7/l4
9/2
10/7
11/3
2/2/71
Uuf iltered Samples
Temp
°C
4.
5-
4.
4.5
4.
11.
13-5
16.5
12-5
9-
8-5
2.0
DO
mg/*
9.8
10.0
10-7
9-6
H-9
8.5
7-6
Susp.
Solids
rag/*
.89
2.98
2.36
.62
.61
Volit .
SS
mg/-0
56
1.06
.88
.46
56
Average
0.45 \JL Millipore Filtered Samples
Nitrogen as N
Org. N
vzl*
98
175
8
94
130
184
91
94
296
331
25
127-2
HH3
V<
14
66
18
38
62
75
19
32
29
40
54
46
41.1
'f03 + N0a
V&/1
69
56
13
7
31*
11
11
19
14
6
9
22
22.6
Tot. N
m/t
181
297
39
139
226
270
121
l45
44
342
394
93
191
Phosphorus as P
P04
MS/'
61
55
10
10
12
7
7
12
9
3
16
17
ie-3
Tot. P
Mg/^
84
59
58
20
13
18
15
27
62
19
16
24
34.6
Cl"
mgy $>
.28
17
.24
54
33
PH
8.0
7-2
7-2
7-0
6-9
7-2
7-1
7-6
7-5
6.8
6-9
ALk.
as
CaCo3
mg/^
36.8
65-2
42.2
M-5
Cond.
(10-)
mhos
96.
78.
59-
47-
44.
60.
80.
83.
99-
121.
104.
90.0
80.1
DOLLAR CREEK ANALYSES
11/-/69
12/4
1/9/70
1/28
2/10
2/23
4/29
5/25
6/30
7/14
a/2
10/7
11/3
6.0
2.0
1.0
1.0
3.0
3-0
6.5
l4.o
17-0
16.0
12.8
7.5
10.8
10.2
10.9
11.4
8.2
10.7
9-8
8.2
7-5
2.06
6-79
11.58
2.80
1.21
3-01
5-05
1.25
Average
161
84
160
86
122
218
136
142
115
36
68
50
114.8
5
27
28
50
28
30
32
31
14
44
10
10
52
27-8
12
6
37
18
27
33
23
14
9
29
22
2
17
19.2
178
117
228
141
185
273
181
165
188
68
80
119
160.3
9
9
14
13
10
10
7
6
f.
8
17
L
10
9-5
19
12
27
18
33
22
125
13
14
13
83
42
10
33-2
49
15
09
51
31
7-4
7-3
7-6
7-6
7.2
7.0
7-1
6.9
7-6
7-6
7.4
7-2
^3-5
47.8
46.2
76
72
60
39
53
51
59
48
64
91
87
98
88
68.2
WATSON CREEK ANALYSES
11/4/69
12/4
1/7/70
1/28
2/10
2/23
4/29
5/25
6/30
7/14
9/2
10/7
H/3
4.0
-0
0.5
0-5
4-5
2.0
5-0
13-0
16.4
10.3
5-0
3-0
11.2
11.2
10.9
11-5
10.6
11.2
10.1
8.6
8.1
3-24
10-39
3.48
26.96
1.20
2.42
1.22
3.18
Average
156
136
222
170
106
103
35^
218
98
34
33
88
143.2
17
37
30
98
32
42
57
34
12
64
-------
TABLE E-l (Continued)
BIACKWOOD GREEK ANALYSES
Date
11/4/69
12/4
1/7/70
1/28
2/10
2/23
4/29
5/25
6/30
7/14
9/2
10/7
.11/3
2/2
Temp
° C ,
5-0 \
-.0
2.0
1.0 '
4.0
2.5
4.0
7-8
11.0
,17.8
9-5
5-5
5-0
3-0 -
Unf iltered Samples
DO
mg -^
'.ii.5
11.1
11.0'
il.o
10.6.
11.3
11-5
9-2
9-3
Susp .
,Solids
TKg/ i
.84
78
1.32
.80
34
Volit.
SS
rug/ 1
56
45
.42
45
.12
Average
0.45 (i Millipore Filtered Samples
Nitrogen as H
Org. N
MS/^
2^2
165
166
134
106
38
96
86
36
50
109
24o
300
8
127
NH3
ml i-
44
26
34
38
12
45
47
66
<1
V
28
4l
ho
47
55-7
N03 + N02
M/^
52
3
110
80
1+
32
55
33
14
l
5
-------
TAHLE E-l (Continued)
INCLINE CREEK ANALYSES
11/4/69
12/1|
1/7/70
1/28
2/10
2/23
It/29
5/25
6/50
7/14
9/2
10/7
11/5
2/a
Temp
° C
0.0
5-0
0-5
1-5
6.0
8.0
14.0
18.0
17-5
14.8
6-5
6.2
4.0
Unfiltered Samples
mi/ 2
10.5
10.4
11. U
9-9
10.1*
9-7
8.6
8.1
Guop.
me/ 1
26.71
21.65
10.78
U. 27
9-57
Vollt.
S3
m^ -I
1.6k
4.49
2.27
1-15
2.02
Average
O.'iJ ji Milllporo Filtered r>nm|i]eo
NHroKori iu; N
Ore. N
M/t
237
118
552
448
536
500
170
208
51'
70
156
91
68
175
215.8
Nil,
«!/«
75
no
75
85
119
64
556
12
17
61*
12
lit
52
28
79-2
N03 + N02
H:/^
78
25
91
10
98
158
>»5
50
17
8
20
5
17
100
W. It
Tot. N
W/t
2f,8
1«3
518
5-'H
605
702
751
250
68
ll*2
168
110
117
505
557-1*
I'lioiiphoruii nuP
P04
n",A
12
15
17
25
19
Uit
10
9
15
13
15
6
26
17.2
Tot. P
MB/'
18
18
25
ay
51
101
30
14
27
17
52
3'*
fj5
55-5
Cl
mis/ I
O.llJ
0.52
0.50
2.1*6
pll
7-3
7-0
7-1
7.S
7-2
7-0
7-0
7.0
7-1*
7-?
7.2
7-1
Alk.
as
CaCo3
rag/*
23.1*
55-5
37-1
Cond.
(io-p)
mhos
57
50
61*
52
67
54
46
1*0
65
54
65
67
28
51*. 1*
MILL CKEEK ANALYSES
ll/i*/69
12/1*
1/7/70
1/28
2/10
2/23
4/29
0-5
11.2
Average
871
ll*32
826
1.01*3
352
172
2U8
257.3
31*8
18?
104
215.
1571
1791
1178
1515.5
57
62
19
39-5
37'
103
52
57-3
7-4
7-0
7-1
74
56
55
61-7
TUNNEL CKEEK ANALYSES
11/4/69
12/1*
1/7/70
1/28
2/10
2/25
It/29
5/25
6/50
7/14
9/2
10/7
11/3
2/2
7-0
5-0
5-0
1.0
5-0
4.0
5-0
10.0
14.1
12.6
9.0
5-o
5-5
4.0
10.6
10.7
10.6
11.0
9-9
10.9
10.0
9-5
8.7
4.02
4.05
5.50
5-72
4.72
2.56
2.66
5-38
2.15
2.82
Average
228
118
478
450
53
89
148
252
151
77
106
78
144
86
174.1
55
47
^
56
16
26
50
24
10
55
5
19
^
16
29.4
22
28
49
39
55
56
56
23
12
11
22
4
16
45
26.9
285
195
561
5^5
102
151
214
279
175
1^5
151
101
203
1^7
230.4
13
14
16
15
17
14
11
5
10
15
17
9
9
21
13-1
21
17
26
18
38
29
21
13
13
17
25
52
12
54
25.4
0.52
0.25
07
-47
.48
56
7-3
7-0
7-6
7-3
7-1
7-0
7-1
7.0
7-5
7-4
7-2
7-1
7-0
29.5
56.1
54.6
56.7
62
157
55
46
59
49
67
52
65
72
71
75
67
66
68.6
MABLETTE CKEEK ANALYSES
11/4/69
12/4
1/7/70
1/28
2/10
2/25
4/29
5/25
6/30
7/JA
9/2
10/7
11/3
2/2
7-0
2.0
3-0
1-5
4.0
5-0
U.5
10.0
18.0
15-5
l1*. 5
7-0
5-5
3.0
10.6
10.2
10.6
11. i.
10.5
10.8
9-6
9-8
8.0
2.95
1.96
1.62
2.86
16.56
1.51
0.89
0.78
1.52
3.44
Average
19'i
15^
225
239
204
201
297
290
189
208
151
88
197
232
204-9
20
117
51
93
27
22
40
37
19
31*
3
15
18
44
39-1
55
37
50
24
25
30
1)2
48
84
78
73
39
52
50
44.60
275
508
306
556
256
253
379
375
292
320
227
142
247
306
208.7
10
15
5
0
9
10
13
4
9
10
20
17
6
14
10.7
109
10
14
ll
21
13
13
7
13
15
29
29
8
17 .
28.4
.28
.48
.20
50
-78
^
7-4
7-3
7.6
7-6
7-0
7.1
7-1
6.7
7-5
7.1
7-2
7-0
6-9
25.4
44.0
25.8
25-5
75
67
42
55
49
40
56
46
89
59
95
86
51
44
59.4
-------
TABLE E-l (Continued)
FIRST CREEK ANALYSES
Date
11/7/70
1/28
2/10
2/25
4/29
5/25
6/30
7/l4
9/2
10/7
11/3
2/2
Temp
° C
2.0
1.0
4-5
5-0
7-5
14-5
16.0
14.0
13-0
7.0
7-5
3-0
Unfiltered Samples
DO
w*
10.8
11.4
10.2
11.2
8.9
8.2
Susp.
Solids
mg/£
10.07
24.35
7-78
45.74
74.12
Volit.
SS
^Ji
2.68
4.58
1.94
6.28
22.90
Average
0.45 [i Millipore Filtered Samples
Nitrogen as N
Org. N
tit
199
344
218
304
156
134
77
60
48
144
430
192.2
NH3
MS/ «
28
66
36
57
42
9
56
12
57
48
37-4
N03 + NOa
ml I
31
39
31
28
l»8
70
34
16
l
19
65
34.7
Tot. N
W5/*
258
285
389
246
213
167
76
61
220
543
264.3
Phosphorus asP
P04
MS/*
13
9
13
16
>4
6
11
31
5
15
24
13-4
Tot. P
MS/*
23
13
33
27
10
28
18
65
6
21
50
27.2
mg/.«
-29
.28
.01
.47
1.47
.50
pH
7-7
Y-5
7-1
7-1
7-0
Y-5
7-5
7-4
7-1
6.9
Alk.
CaCo3
**/'
31-8
1(3.4
47.2
36.0
Cond.
(10~F)
mhos
66
51
t-5
55
39
51
69
83
85
88
63
65.0
SECOND CREEK ANALYSES
11/4/69
12/4
1/7/70
1/28
2/10
2/23
4/29
5/25
6/30
7/14
9/2
10/7
11/3
8.0
3.0
1.5
-.0
5-o
15.0
22.0
17-5
15-5
6.0
8.0
10.2
10.5
10.9
11.6
10.4
9-4
8.6
6-9
94.94
14.60
6.22
2.62
16.82
3.22
1.62
0.76
Average
182
2('j8
'i'j'(
517
764
2487
356
213
151
213
74
98
463-3
1(7
27
C?i?
Y2
99
361
40
12
65
26
16
28
67-9
20
29
59
65
56
81
48
3
9
ll
3
17
33-4
2^9
324
654
919
2929
444
228
225
250
93
143
564.7
22
17
12
12
22
25
17
20
18
12
15
16
17-3
29
25
21
21
62
89
22
32
26
34
100
16
39-8
0,34
0.28
0.02
0.23
.22
7-3
7-2
7-7
7-5
7-2
7-1
7.0
7.6
7-3
7-3
6.8
29.6
38.0
35-7
71
62
75
48
72
51
40
48
66
74
73
72
62.7
ROSE KNOB (WOOD) CREEK ANALYSES
11/4/69
12/4
1/7/70
1/28
2/10
2/23
4/29
5/25
/30
7/14
9/2
10/7
11/3
2/2
8.0
3-0
0.5
-.0
5.0
5-5
7-0
15-5
19-5
18.0
15-8
7.0
6-5
3.0
11.4
10.7
11.1
11.6
10.4
10.7
7.5
8.3
7-6
7-56
27.89
4-99
29.80
6.74
1.70
4.27
1.25
2.88
1.79
Average
381
321
238
297
261
170
258
328
65
94
156
84
185
219-3
67
22
22
54
28
55
17
10
4o
32
19
30
15
32.6
35
88
152
133
105
468
81
106
5
14
18
25
116
96.4
483
431
412
484
394
693
381
343
119
Ikk
179
139
316
348.5
26
23
19
17
14
18
17
6
11
17
20
6
12
23
16.4
35
32
31
20
31
23
33
21
22
22
43
40
15
52
30.0
0.21
0.26
0.11
0.26
55
.28
7.4
6.9
7-6
7-5
7.2
7-4
7.1
7.0
7-5
7-3
7-2
6.9
6.9
26
31-5
30.8
30.5
58
53
44
46
57
49
55
36
45
56
64
63
65
62
53.8
THIRD CREEK ANALYSES
11/4/69
12/4
1/7/70
1/28
2/10
2/23
4/29
5/25
6/30
7/14
9/2
10/7
11/3
2/2
4.0
3-0
1.0
0-5
5-5
5-0
9.0
13.0
19-5
20.5
17-5
7.0
6.2
4-5
10.3
10.8
10.9
11.8
9-9
9-9
8.1
9-0
7-5
9-53
12.40
6.08
5-19
16.36
2.14
2.56
1.38
1.29
3.01
Average
998
1146
4o4
536
380
335
4 10
304
309
172
158
101
139
170
397-3
161
91
56
81
26
37
92
12
31
42
320
12
32
4o
73-8
78
19
54
80
42
37
39
45
28
420
84
8
22
50
71-7
1237
1256
514
697
448
409
541
361
368
634
562
121
193
260
542.9
20
25
14
19
20
17
14
9
17
54
7
16
16
19.4
47
25
22
26
65
22
32
11
14
17 -43
69 .41
39 .15
16 .63
46 1.57
32.2 .64
7-4
7-0
7.3
7-5
7.1
7-2
7-1
6.9
7-4
7-2
7-2
7-1
7-0
26.2
36.1
32.1
34.0
65
55
48
48
68
60
50
27
54
63
79
73
60
59
57.8
lit-6
-------
TABLE E-l (Continued)
TOCAN HOUSE CREEK ANALYSES
Date
11/4/69
12/4
1/7/70
1/28
2/10
2/23
4/29
5/25
6/30
7/i4
9/2
10/7
u/5
2/2
Temp
0 Q
7-0
-.0
0.5
~-5
4.0
4.0
4.0
11.5
14.0
13-8
10.0
5.0
5-0
2-5
Unf iltered Samples
DO
mg/.«
11.4
11-3
11.4
11.4
10.6
9-7
11-5
8.5
8-5
Suap.
Solids
«B/J
1.94
2.23
2.96
1.13
4.72
Volit.
ss
ms/1
1.01
1-25
1-31
0.65
1.90
Average
0.45 n Millipore Filtered Samples
Nitrogen as N
Org. N
MS/-*
139
132
325
46
189
163
182
242
166
166
< i
56
354
122
163.0
NH3
MS/^
32
54
26
58
9
42
36
37
22
38
2
20
10
398
56.0
N03 + N0a
W5/J!
30
23
49
47
29
35
38
107
13
23
19
it
12
39
33-4
Tot. N
Wl *
201
209
400
151
227
240
256
386
201
227
22
80
376
559
252.5
Phosphorus as P
P04
MgA
8
4
9
6
6
5
6
6
4
10
11
it
6
ll
6.8
Tot. P
W,l!>
42
9
29
9
34
20
10
22
46
21
54
69
10
18
28.1
. -
mg/i
31
.59
.39
.86
1-96
.82
PH
7-3
7-?
7-8
7-7
7-1
7-1
7-0
I-'*!
7-4
7-9
7-8
7.5
7.4
Alk.
as
CaCo3
me/*
70-5
73-5
68.1
70-9
Cond.
(io~p)
mhos
114
176
102
96
114
90
68
73
129
150
127
137
109
110
113-9
McFAUL CREEK ANALYSES
11/4/69
12/4
1/7/70
1/28
2/10
2/23
4/29
5/25
6/30
7-0
1.0
0.5
0.5
3-5
4.0
8.0
16.8
18.8
10.8
10.9
11.2
11.4
10.8
10.1
9-5
7-4
7-5
Average
246
134
386
26l
189
129
201
316
192
228.2
38
74
17
90
16
42
25
37
36
41.7
52
33
52
35
37
42
21
12
13
33-0
336
24l
455
386
242
213
247
365
24 1
302.9
18
12
13
12
9
10
it
8
7
10.3
4o
19
27
18
36
35
9
25
14
24.8
7-5
7-2
7-7
7-6
7-4
7-1
7-1
7-2
7-7
92
89
72
68
103
68
68
64
94
79-8
EDGEWOOD CREEK ANALYSES
11/4/69
12/4
1/7/70
1/28
2/10
2/23
4/29
5/25
6/30
7/14
9/2
10/7
11/5
2/2
7.0
3-0
3.0
2-5
5-0
5-0
7-0
14.0
l4.o
16.0
12.0
6-5
6.0
4.0
10.2
10.5
10.3
11.1
9-9
10.8
10.9
8.9
8.4
3.82
2.88
3.48
2.15
21.51
1.44
1.10
1.12
0.82
3-73
Average
316
187
525
328
189
118
146
380
201
106
14
263
104
122
199-9
60
67
24
110
31
43
54
86
36
58
< 1
38
22
92
51-5
4i
34
49
84
75
93
65
43
36
31
57
18
32
75
52.4
417
288
398
522
295
254
265
509
273
195
72
319
158
289
303.9
27
15
18
21
14
14
12
16
18
20
18
10
15
17
16.8
39
19
4o
26
37
22
16
35
23
31
44
100
18
24
35-9
-72
75
-63
-96
5-91
1-79
7.4
7-0
7-6
7-4
7-2
7-1
7-0
7-1
7-5
7-7
7-6
7-2
7.1
46.0
47.0
42.8
50.6
78
71
67
64
94
69
62
69
97
98
92
98
75
77
79-4
TRUCKEE - TROUT CREEK ANALYSES
11/4/69
12/4
1/7/70
1/28
2/10
2/23
4/29
5/25
6/23
7/14
9/2
10/7
11/3
2/2
7.0
1-0
0-5
-.0
3.0
4.0
4-5
10.0
14-5
21.6
17-5
9-0
6-5
2.8
10.2
10.8
11.0
10.4
10.96
11-3
9.4
8.08
3.88
4.76
1.85
1.32
2.86
2.07
1.63
0.56
0.52
1-55
Average
252
208
57
364 ,
380
211
124
194
130
130
412
252
194
130
217.0
21
60
59
101
33
54
61
24
20
48
25
18
28
8
40.0
62
95
100
72
85
81
62
23
15
8
29
6l
45
68
57-6
555
5f>5
?. Hi
537
498
346
247
24i
165
186
466
331
267
206
314.6
6
7
7
10
12
9
It
2
2
9
6
4
8
14
6-9
17
13
13
14
28
25
9
5
14
20
9
7
10
43
16.2
1-57
4.02
5-11
2-59
3-3
7.1
6.9
7-2
7-2
7.1
6.9
6-9
7-1
7.1
7-1
7-3
7-0
6.8
12.7
30-5
25-1
22.8
60
57
54
28
1.6
42
55
21
25
15
72
84
61
48
47-7
-------
TABLE E-l (Continued)
TAYLOR CREEK ANALYSES
Date
11/4/69
12/1)
1/T/TO
1/28
2/10
2/2J
V29
5/25
6/30
7/14
9/2
10/7
11/3
2/2
Temp
" C
9-0
5.0
5-0
2.0
^ 5
5.0
7-0
12.2
18.2
18.0
17-0
10.0
4.5
k.O
Unfiltered Samples
tog/ i
11.1
8.7
9-9
10.8
10.2
10.3
9.8
8.7
7-7
Susp .
Solids
mg/ 1
1.22
0.51
0.26
0.88
0.66
Vclit.
SS
msj I,
0.72
0.39
0.37
0.54
0.66
Average
0.1*5 p. Millipore Filtered Samples
Nitrogen as W
Org . N
WS/^
172
153
204
206
198
175
175
117
108
156
5
233
111
79
11*9. it
NH3
Pg/^
28
15
51
42
17
43
32
26
30
1*9
-------
TABLE E-l (Continued)
MEEKS CREEK ANALYSES
Date
11/4/69
12/4
1/7/70
1/28
2/10
2/23
4/29
5/25
6/30
7/14
9/2
10/7
11/3
2/2
Temp
° C
5-0
-.0
1.0
1.0
2.0
2.0
2.0
8.2
l<*-3
17-0
12.0
<*-5
1-5
Unflltered Samples
DO
\ms/ &
11.4
10.4
10.8
9.4
10.4
11.0
11.4
8.6
7-5
Sue p.
Solids
me/ H
.81
7-93
3-16
56
Volit.
SS
ng/4
56
2.67
1.8o
Averuge
0.45 u Millipore Filtered Samples
Nitrogen as N
Org. N
MC/-2
185
132
237
335
132
194
103
156
118
58
122
594
98
174.2
rai3
Wl*
39
28
9
62
29
49
44
92
46
22
<1
39
42
38.6
N03 t- N02
WJ/-S
4
18
42
13
26
17
4i
6
8
16
8
13
28
18.5
Tot. N
V&l *
228
178
288
410
187
260
188
254
172
96
130
446
168
231.0
Phosphorus asP
P0«
ME/*
10
7
7
7
6
5
2
2
2
5
32
24
10
9.2
Tot. P
W.I*
12
9
18
13
19
16
5
13
6
12
52
33
12
16.5
Cl"
ms/t
.28
23
.38
59
37
PH
7-3
7-0
7-0
7-2
6.9
7-0
6.9
7.1
7.1
6.7
6.8
6.5
Alk.
as
CaCo3
ing/*
8.8
32.0
12.4
Cond.
(io-p)
mhos
35
30
22
18
23
20
18
13
18
25
92
73
26
31.8
GENERAL CREEK ANALYSES
11/4/69
12/4
1/7/70
1/28
2/10
2/23
4/29
5/25
6/23
7/14
9/2
10/7
n/3
2/2
4.0
-.0
0.5
1.0
3.0
2-5
3-0
7-0
14.0
17-0
9-8
5-5
5-0
2.0
11-9
10.8
10.8
11.0
10.80
10-92
11.0
11.8
8.06
0.35
0.61
0.49
1.40
0.22
0.32
0.45
0.31
0.97
0.22
Average
70
146
154
189
170
237
148
156
48
70
43
228
354
44
146.9
34
22
18
50
38
46
46
64
30
20
<1
28
16
6
29.9
25
10
38
13
17
8
29
4
9
6
*5
37-7
48
84
68
2l(
13
9
1(1
15
13
ll
1(7
13
93
36.8
229
235
277
213
119
lU9
251
275
78
178
167
195
201
197-5
2k
*3
1*0
27
50
37
1*6
30
30
1(9
58
51
52
^l
-------
TABIE E-l (Continued)
Date
ll/'./M
l'y<*
1/Y/YO
2/l'->
2/23
4/29
5/25
6/30
7/14
9/2
10/7
11/3
Temp
" C
11.0
1-5
2.0
0-5
4.0
4.0
5-5
14-5
16.0
14.5
10.2
5-0
5-5
DO
mg/ J>
10.0
10.3
9-9
10.8
9-7
10.3
10.9
8.0
7-5
Susp.
Solids
mg/t
6.38
13-78
4.Y4
2.22
Volit.
SS
ms/t
3-2Y
6.88
2.39
1.27
0.45 )-i Millipore Filtered Samples
Nitrogen as N
Org. N
UK/-*
565
332
457
445
244
192
175
266
242
204
170
132
126
Average
HH3
MS/-«
90
58
52
330
30
26
24
40
32
22
<]_
20
10
56.6
N03 + N02
M6/-2
93
166
131
261
74
l4o
48
46
97
175
104
48
119-4
Tot. N
MS/-8
548
556
690
1036
348
358
35'*
320
323
346
256
184
443.3
Phosphorus as P
P04
m't
75
8
4
10
7
7
4
6
6
ll
5
6
4
9-8
Tot. P
Mg/.«
49
12
18
14
37
18
18
13
49
34
18
14
7
26.0
mg/^
0-52
1.00
0.20
0.89
65
PH
7-3
7-1
Y-6
Y-b
Y-2
7-2
Y-l
Y-5
7-6
Y-1*
7-2
7-2
Alk.
CaCo3
mg/*
36- Y
40-0
43-7
Cond.
(io-p)
mhos
74
74
58
53
70
51*
54
66
101.0
81
85
85
57
70.2
BLISS CREEK ANALYSES __,
11/W69
12/1.
1/7/70
1/28
2/10
2/23
4/29
5/25
6/30
5-0
1.0
3-0
lt.0
8.0
17.0
21.7
6.8
2.1*
U.l
3-1
3-2
8. It
G.O
l*.0
Average
926
98!.
950
62l*
321
538
600
6'+ 1*
698.1*
103
lit It
12li
96
'*8
56
50
50
83.9
35
12
20
°2
18
1.2
27
17
2k .1
loft
llltO
1091*
7'*2
387
616
677
711
806.1*
10
8
12
13
<1
7
t*
6
7-6
22
15
28
1*0
1*9
18
12
16
32.0
7-1*
7-3
7-6
7-1
7-3
6-9
7-6
7-6
118
112
67
88
76
68
78
102
88.6
SLAUGHTER CREEK ANALYSES
ll/lt/69
12/lt
1/7/70
1/28
2/10
2/23
l*/29
5/25
6/30
7/14
9/2
10/7
11/3
10.0
2.0
1.0
-.0
5.0
8.0
21.0
22.5
22.5
17-3
8.0
6-5
10.5
10.9
10.1*
9-8
9.6
10.9
9-0
6.6
7-5
6.45
2.76
4.79
6.02
2.18
1.05
1.52
2.02
Average
292
285
522
529
512
326
550
600
304
142
316
136
134
357-5
79
93
27
328
263
286
88
92
20
49
17
17
ll
105.4
110
128
215
111
160
174
97
63
7
3
58
43
55
94.2
48l
506
764
968
935
786
735
755
331
194
391
196
200
557.1
13
7
13
14
12
< 1
5
21
4
7
5
4
12
9-0
18
12
23
20
32
35
9
4o
11
20
14
6
14
19-5
0.44
2.58
0.36
0.46
96
7-5
Y.I
7-6
7.6
7-2
7-3
7-3
7-5
7-7
7-5
7-5
7-1
42.3
52.4
36-5
82
82
90
82
100
84
68
78
232
96.3
132.0
136
68.2
102-3
GLEHBROOK CHEEK ANALYSES
11/4/69
12/4
1/7/70
1/28
2/10
2/23
4/29
5/25
6/30
7/14
9/2
10/Y
11/3
6.0
1.0
5-0
12.0
14.0
6-5
6.5
10.8
11.0
10.6
9-5
8.0
10.29
8.24
6.02
3.21
2.28
2.02
Average
288
84
242
208
163
182
88
134
173-6
130
52
40
30
17
23
16
11
39-9
31
27
214
113
84
<1
22
55
68.3
449
163
496
351
264
205
126
200
281. Y
18
13
12
14
16
4
1
12
11.3
71
15
18
32
19
55
9
14
29.1
3-91
.46
2.19
7-5
7-1
7-1
7-5
7-7
7-7
7.1
116.5
36.5
240
236
210
138
123
324
330
68
208.6
150
-------
TABLE E-2
NUTHIEHT INVENTORY OF STREAMS DISCHAHOIHO INTO LAKE TAHOE
Sub-Bflflin
Ko.
1
2
3
k
5
6
7
8
9
10
11
12
«
15
16
17
18
19
20
21
22
25
2U
25
26
27
28
29
50
31
32
53
3*
35
56
37
38
39
i.0
1*1
L2
u.
1*1*
U5
1.6
fc?
us
50
51
52
53
55
56
57
58
59
60
' 61
6?
63
Hume
Tahoe Gtote Park Ck/
Burton CK.
Burton Ck/
Lnks Forest Ck.f
Dollar Ck.
Cedar Flats1
Wataon Ck.
Carrwlian Bay Ck .
Carnellan Canyon CK.
TBhoe Vieta
Griff Creek1"
Klnge Beach1"
East Ptate Line Point1"
Second Creek
Unnamed Creek So. lf
Poss Knob (Wood) Creek
Third Creek
Incline Creek
Hill Creek
Tunnel Creek
Unnamed Creek So. 2
Sand Harbor1"
Marlette Creek
Secret Harbor CreeK.d
Bliss Creek
Deadman Polntf
Slaughter Houae Cr«ek
Glenbrook Creek
Horth Logan Houae Ck.
Logan Houae Creek
Cave Rockf
Linclon Creekf
3kylandf
Forth Zephyr Creek
Zephyr Creek
Fourth Zephyr Creek
McFnui Creek
Burke Creekf
Edgewood Creek
Bijou Perkf
Bijouf
Trout Creek6
Upper Truckee Rivere
Cflnrp Richardson
Taylor Creek
Teliae
Cascade
Eagle Creek
Bllso State P*rkf
flublcon Creek1"
Psradlue Flat
Lonely Gulch Creek
Sierra Creekf
Week's Creek
McKinney Creek
Quail Creek
Homevood Creek
Madden Creek
Eflgle Rock
Blaekvood Creek
Vard Creefc
Total
Average
Runoff
ac-ft
'X>0
3,600
1,100
i»oo
1,000
1,300
1,900
1,100
2,7CO
5,800
?,8oo
800
600
i, 300
1,300
500
1,900
5,600
k,l<00
1,600
1,200
9OO
1,600
3,600
3,900
100
100
Nltroeen"
Orgnnlc-ft
Ml'
1?7
1P7
125
119
115
129
Ik5
Ik 3
Ik5
fc58
162
162
162
192
k63
3k 1
219
397
199
I,0k3
17k
17k
17k
205
508
696
698
k8
I'lO
560
166
58
Ikl
rtl
333
195
k7k
2,OkO
755
159
119
725
209
511
2,730
1,075
2,0k5
256
192
5k 1
905
I,k7k
86
86
1,500
200
800
100 .
900
100
1,100
600
100
1,700
2,000
3,000
1,500
700
22,000
71,500
i,100
33,kOO
5,koo
7,800
17,000
5,200
1,000
1,300
1,200
15,kOO
8 500
10,500
1,700
1,900
2,kOO
700
23,300
18,300
310,900
17k
165
165
172..
182
191
201
210
219
228
21k
200
202
20k
207
207
178
Ik 9
15k
162
127
137
Ik6
156
165
17k
Ik 7
186
165
ikk
123
125
127
rn
18»
320
ko
160
21
201
25
271
155
27
k75
525
735
372
175
5,6ko
18, 15k
2kO
6,10k
1,020
1,550
2,6W
538
179
2k y
2k 3
'2,860
1,533
2,595
5lili
3k6
3«2
107
5,630
2,222
O,lk5
m -H
3
«/l
kl
kl
56
3?
28
55
58
38
38
178
58
38
58
37
68
50
55
7k
87
257
29
29
29
39
81
6k
8k
ko
56
56
5k
52
50
k8
k6
kb
k2
k7
52
5k
56
58
58
k8
38
3k
32
31
32
3k
36
38
39
30
kl
ko
39
38
57
56
58
k8
k«
k5
18 1
k9
16
5k
53
88
51
126
850
177
57
28
59
108
51
77
508
k70
505
k5
32
57
172
588
10
10
7k
Ik
55
7
57
6
65
5k
5
88 '
U5
191
99
k8
1,565
5,087
65
1,557
225
506
6k6
126
( N03 * NO ) N
MU/I
23
25
21
20
19
29
58
58
58
221
57
57
57
55
55
65
96
72
5k
215
27
27
27
k5
107
2k
2k
ks
25
101
28
10
25
k6
88
51
126
1,030
172
56
27
56
55
ko
22k
k95
292
kl8
ko
50
55
199
512
5
5
Total
as/'
Ml
191
180
171
160
191
218
218
218
857
237
257
257
26k
565
k56
5k8
5k5
5kO
1,515
250
250
250
289
500
806
806
ks
211
8kk
2k 3
6k
196
305
508
29k
722
3,900
1,105
235
17k
'121
900
280
811
3,730
1,837
2,970
338
25k
k51
1,275
2,390
99
99
(Included vith Sub-Bflnin No. 25)
68
55
55
55
53
35
35
55
35
55
k2
52
51
119
kB
k8
56
25
30
20
59
5k
125
8
32
k
56
li
k5
2k
k
69
105
191
9k
k2
1,295
k,210
k9
9k2
199
191
815
133
282
255
255
259
267
27k
282
289
296
503
303
30k
307
309
31k
51k
26?
210
218
215
198
203
519
62
2k8
32
295
5k
580
212
56
652
7145
1,120
565
265
8,k75
27,538
55k
8,605
l,kkk
2,057
k,129
797
phosphorus
P0« -r
M8/<
18
IB
16
13
10
10
9
9
9
89
11
11
11
13
17
17
16
19
18
39
13
13
13
11
9
8
8
11
7
7
7
8
8
9
9
10
10
Ik
17
Ik
11
8
8
7
5
7
6
5
6
Ke
so
80
22
6
12
16
21
12
50
k!5
51
11
8
21
27
10
37
131
97
76
19
Ik
26
kfl
k3
1
1
20
2
7
1
9
1
12
7
1
21
3k
63
26
9
216
702
9
205
U6
57
10k
2k
(Included vith Sub-Baain No. 50)
29
57
56
- 6kl
315
528
85
91
112
52
1,029
852
18,k66
31
27
53
19
13
kl
39
37
56
35
17
kl
58
k2
5k
312
156
55k
85
91
109
51
1,000
582
15,626
211
219
?26
231
191
270
2>i6
222
108
198
197
15k
273
2k 9
350
553
5,797
1,991
3,k77
512
517
585
170
5,630
3,k57
10k, 278
7
7
8
9
10
5
6
7
8
8
7
11
10
9
11
12
ne
10k
6k
13
16
2k
7
200
2k7
5,686
Total
US/'
n
55
5k
3k
33
50
26
26
26
113
26
26
26
27
ko
-j-j
50
52
ko
57
25
25,
25
28
23
52
52
29
28
28
28
27
27
26
26
25
25
50
3k
29
25
2i
21
16
12
Ifl
9
10
12
ka
59
155
kfi
17
ko
liB
61
35
86
527
121
25
19
k3
6k
21
70
220
216
112
37
28
U9
12k
110
k
U
53
7
27
3
30
5
35
19
5
52
7k
125
53
21
567
l,8kl
22
k92
119
86
209
k7
15
15
16
17
18
29
26
25
20
20
20
23
22
16
2k
2k
279
188
375
5k
5k
59
17
572
516
8,585
Chlorjdt
"8/1
0.55
0.33
0.3?
0.52
0.51
0.53
0.56
0.56
0.36
1.00
0.39
O.li2
O.k6
o, 50
0.22
0.25
0.28
0.6k
1.05
1.05
0.36
0.56
0.56
O.k5
0.8o
0.80
0.80
2.19
0.82
0.82
0.82
0.81
0.61
0.80
0.79
0.76
0.78
0.77
1.79
2.0k
2.29
2.5k
2.5k
O.k5
O.k5
0.57
0.57
0.52
0.55
0.3k
0.55
0.36
0.57
O.kl
O.kl
O.kl
O.k2
O.k2
0.35
0.27
O.k6
1.10
kg
36k
1,11-18
k52
157
380
5?7
Bko
U66
1,191
k,66o
1,818
k]2
539
7V7
351
155
655
k,koo
5,670
2,060
550
397
707
1,985
3,830
98
98
k,050
201
805
100
895
9)
1,080
58
96
1,6?5
1,885
6,590
5,750
1,965
68,5k2
222,76)
608
I8,k56
2,k51
3,5kO
6,673
1,295
1417
558
530
6,081
k,275
5,280
655
980
i,?37
501
7,717
10,326
k20,857
Conductivity
(10-6) (j, 103)"
mhos
BO
00
76
7?
68
67
66
66
66
128
66
66
66
f.
05
63
59
5k
58
59
62
69
69
69
59
86
89
89
209
Ilk
Ilk
110
105
100
95
90
85
80
79
79
70
62
5k
5k
26
26
k5
15
17
20
23
26
20
52
56
59
ko
k2
k5
50
57
58
50
kg
62
2k 7
72
25
58
7S
108
6?
218
k!8
215
15
51'
73
70
25
88
279
22}
85
71
53
95
182
288
8
8
270
20
78
Ik
81
9
90
k6
7
117
136
203
9O
57
1,020
3,315
25
7k6
20Q
87
2k8
55
20
29
30
568
265
552
58
68
89
50
l,lko
911
I,.,kk8
"Baaed on 50 In. of precipitation at Tahoe City, California '
Nitrogen valuea have teen rounded-off to the neareat vhole number, therefore, the value for total nltroaen »ay not be the apparent ou-ation total. ALio Individual
ralues are mlaalng, thua, altering the total.
^Baeed on the aaaumption that 1.0 micro ohm equale 0,7 rag/i
"Value, preaented are the averase of Secret Harbor Creek (25) and Slaughter Home Creek (28)
"Sawllns location la at the confluence of Trout Creek and the Upper Truckee Blver, therefore, both atresma are repre.ented by the a.»e con.tltuent valuea
rSaoplea not collected due to lack of per«ment atreana or in ao.e caae, difficult »-n,M area, - vajuea aasigned are prorrted and/or eatlmeted
151
-------
TABLE E-3
ANALYSES OF PRECIPITATION IK THE TAHOE BASIH
Date
1970
1- 6
1-13
1-20
1-24
2-24
3- 1
11- 1*
11-17
11-30
12- 1
12- 3
12- 9
12-17
12-29
1971
2-18
Type
of
PTGC
>.
s*
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
R/S
R/S
R/S
S
S
S
S
S
S
Sta.
la
2
3
1
2
3
1
2
3
1
2
3
1
2
1
2
3
1
1
1
1
1
1
1
1
1
Average
0,45 n Filtered Samples
Nitrogen as N
Organic
HS/«
132
180
194
168
220
355
252
166
314
264
44
237
285
402
-
184
280
159
1-52
94
150
60
_
102
108
92
191.4
NH3
V&/1
16
51
4o
80
78
150
90
83
96
115
61
93
126
107
144
177
106
212
85
60
67
48
280
86
120
479
117.3
N02 + N03
V&li
19
23
22
60
61
56
24
13
19
29
29
39
92
72
86
59
47
157
69
^5
36
17
55
77
64
220
56
Tot. Ino.
V&ll>
35
73
62
l4o
139
206
114
96
115
144
90
132
218
181
230
236
153
369
154
105
103
65
335
163
184
699
174.6
Total
V&li
167
254
256
308
359
561
366
262
429
4o8
134
369
503
581
-
420
433
528
306
199
253
125
-
265
292
791
357.0
Phosphorus
P04-P
V&li
4
9
18
4
13
13
9
7
12
7
3
18
4
2
12
12
8
15
10
8
10
4
16
7
9
9
9.3
Total
V&l ' I
1
18
25
15
14
18
11
13
17
25
7
24
4
3
17
21
10
20
17
14
16
9
18
10
16
17
14.8
Fe
MS A
<1
<1
<1
-
-
-
_
-
-
<1
<1
<1
-
-
7
1
-------
TABLE E-U
CONTINUOUSLY RECORDED STREAMS IN THE LAKE TAHOE BASE!
Stream
Incline'
Third.
Year
1958-59
59-60
So -Si
61-62
62-63
63-64
61>-65
65-66
66-67
67-68
68-69
69-70
Average %
1958-59
59-SO
60-61
61-62
62-63
63-64
64-65
65-66
66-67
67-68
68-69
69-70
Average %
1958-59
59-60
60-61
61-62
62-63
63-64
64-65
,65-66
66-67
67-68
68-69
69-70
Average i>
1968-69
69-70*
Average Ji
' 1969-70 -
1969-70.
Monthly Flow and Percentage of Yearly Total
October
ac-ft
109 .
89
11?
168
1,730
210
156
246
202
293
162
346
1,053
469
489
560
1,020
1,020
634.
1,620
623
1,610
833
1,750
466
252
209
280
973
603
285
811
229
875
340
951
638
238
-" iki
202
*
0.9
0.5
0.8
0.7
6.7
1.0
0.4
1.5
0.7
1.5
0.3
0.9
1.3
7,6
4.6
4.9
3.1
3.5
6.4
1.6
8.4
1.5
8.3
1.9
5.4
4.0
1.9
1.1
1.1
0.7
1-5
2.0
0.4
2.1
0.3
2.9
0.5
1.7
1.2
1.3
0.6
1.0
5.0
3.1
November
ac-ft
195
79
257
169
775
1,450
264
370
664
242
736
234
1,144
797
684
625
922
1,360
932
1,750
1,050
1,370
1,060
1,480
515
233
273
264
624
2,140
420
1,010
574
581
1,090
887
2,660
601
312
238
*
1.5
0.5
1.8
0.8
3.0
7.2
0.7
2.3
1.8
1.3
1.6
0.6
1.8
8.3
7.7
6.9
3.4
3.2
8.5
2.3
9-1
2.6
7.1
2.4
4.6
4.5
2.1
1.0
1.4
0.6
1.0
7.0
0.6
3.4
0.8
1.9
1.4
1.6
1.6
5.3
1.5
3.6
4.6
3-6
December
ac-ft
211
110
242
245
1,690
653
9,670
303
908
229
558
4,400
1,041
728
690
694
922
1,230
3,790
1,580
1,380
1,110
768
1,830
459
230
339
4l4
1,050
1, S80
11,050
954
1,410
516
651
2,340
2,360
4,260
330
339
i
1.6
0.6
1.7
1.1
6.6
3.2
24.6
1.8
2.5
1.2
1.2
11.6 ,
6.2
7.5
7.1
6.0
3.8
3.2
7.7
9-3
8.2
3.4
5-7
1.7
5.6
5.4
1.9
1.0
1.8
1.0
1.7
4.2
15.1
3.2
2.0
1.7
0.9
4.2
3.9
4.7
10.4
7.3
4.8
5.2
January
ac-ft
663
129
188
293
2,650
549
2,230
356
835
376
1,780
10, 230
1.218
768
696
612
1,350
-1,090
2,700
1,390
1,160
1,220
1,750
3,710
1,098
294
289
407
2,460
1,020
3,990
988
1,190
770
2,230
8,240
3,730
10,340
709
535
*
5-2
0.7
1.3
1.3
10.3
2.7
5.7
2.2
2.3
1.9
3.8
27.0
6.6
8.8
7-5
7.0
3.3
4.7
6.8
6.6
7.2
2.9
6.3
3-9
11.5
6.0
4.6
1.3
1.5
0.9
3.9
3.4
5.4
3.3
1.7
2.6
3.0
14.9
4.3
7.5
_25.3
15-5
-10.4
"8.1
February
ac-ft
1,045
562
487
679
3,920
449
1,090
350
986
2,200
1,350
1,680
1,275
1,089
811
893
3, 440
871
1,810
1,180
1,150
1,810
1,330
2,260
944
719
545
849
7,820
762
2,410
857
1,330
2,360
978
3,250
2,430
3,170
483
-3*5
*
8.2
3.2
3-5
3.0
15.3
2.2
2.8
2.1
2.7
11.4
2.9
4.4
4.8
9.2
10.6
8.2
4.9
12.0
5.4
4.4
6.2
2.9
9-3
3.0
7.0
6.1
3.9
3.2
2.9
2.0
12.3
2.5
3.3
2.9
1.9
7.9
1-3
5.9
4.3
4.9
7.7
6.2
7-.1
5.3
March
ac-ft
1,220
2,039
698
736
1,420
734
1,460
1,280
4,510
2,400
l,24o
1,710
1,599
1,387
916
867
2,000
1,040
2,110
1,700
2,400
1,890
1,550
2,260
1,985
1,846
823
926
2,310
1,180
2,590
2,110
2,980
2,880
1,580
3,380
1,640
1,840
679
491 .
*
9.5
11.7
5.0
3.3
5-5
3.6
3-7
7-8
12.4
12.4
2.6
4.5
6.3
11.5
13-5
9-2
4.7
7.0
6.5
5.2
8.9
6.0
9.8
3-5
7.0
6.7
8.2
8.2
4.3
2.2
3.6
3.9
3-5
7.1
4.3
9.6
2.1
6.1
4.6
3.3
^5
3.8
.9-9
7.5
April
ac-ft
3,245
5,143
2,941
5,630
2,000
3,500
4,960
5,020
1,100
4,110
4,770
3,090
1,985
1,763
1,355
2,900
2,140
1,980
3,450
2,840
1,730
2,320
4,340
2,530
6,135
5,952
4,013
7,720
3,150
4,480
7,320
7,760-.
1,990
5,850
7,190
4,680
4,710
2,250
710
530
*
25-3
29.6
21.0
25.1
7.8
17-4
12.6
30.5
3.0
21.3
10.2
8.1
14.7
14.3
17-1
13.6
15.8
7.4
12.3
8.4
14.8
' 4.3
12.0
9-7
7.8
10.0
25.5
26.5
21.1
17.9
5.0
14.7
10.0
26.0
2.9
19.5
9.6
' 8.5
-12.4
9.4
5-5
7.7
10.4
8.1
May
ac-ft
3,751
5,068
5,155
7,030
6,200
7,380
9,230
6,280
8,040
5,950
19,190
8,750
1,894
1,464
1,567
3,460
5,400
3,000
6,760
3,570
7,120
3,200
11,290
4,94o
7,144
7,624
7,474
13, 140
20,250
11,000
17,070
11,020
15,220
10,050
28,380
14,900
14, 610
6,64o
1,170
1,360
i
29.3
29-2
36.8
31.3
24.2
36.6
23.5
38.2
22.1
30.8
40.8
23.1
29.8
13.7
14.2
15.8
18.9
18.8
18.7
16.5
18.6
17.7
16.5
25.2
15.3
18.2
29-7
34.0
39.4
30.5
31.8
36.2
23.3
37.0
21.9
33.5
37-7
27.0
30.5
29.2
16.2
23.4
17.-1
20.7
June
BC-ft
2,032
3,636
3,390
5,980
4,010
4,330
7A50
l,64o
12,860
2,610
13,820
5,870
1,273
925
1,496
4,400
6,400
2,440
8,900
1,790
10,620
2,1*70
12,080
5,960
4,058
4,274
3,850
15,240
19,510
6,000
17,210
2,950
27,330
4,490
23,100
12,580
10,630
8,990
980
1,850
*
15-9
21.0
24.2
26.6
15.6
21.5
19.0
10.0
35.3
13.5
29.4
15.5
21.9
9.2
9.0
15-1
24.0
22.3
15.2
21.7
9-3
26.4
12.8
26.9
18.4
20.0
16.9
19.1
20.3
35.4
30.7
19.7
23.5
9-9
39.4
14.9
30.7
22.8
35.3
21.2
22.0
21.6
14.3
28.2
July
ac-ft
210
342
360
1,230
887
649
1,900
365
5,430
477
2,590
1,150
449
370
490
1,960
2,760
938
4,770
859
8,270
1,090
5,690
3,000
688
6o4
703
2,820
3,930
1,280
6,350
793
13,780
926
7,520
2,750
4,950
1,9OO
499
403
*
1.6
2.0
2.6
5-5
5.5
3.2
4.8
2.2
14.9
2.5
5.5
3.0
5.0
3.2
3.6
4.9
10.7
9-6
5.8
11.7
4.5
20.6
5.6
12.7
9.3
10.4
2.9
2.7
3.7
6.6-
6.2
4.2
8.7
2.7
19.9
3.1
10.0
5.0
7.9
10.0
4.6
7.5"
7.3 .
6,1-
August
ac-ft
54
109
96
208
244
168
604
146
600
300
593
341
381
264
391
795
1,410
554
3,010
46o
2,910
706
2,550
1,450
255
220
261
673
973
397
3,530
335
2,360
434
1,450
754
1,610
462
346-.
150
%
0.4
0.6
0.7
0.9
1.0
0.8
1.5
0.9
i.S
1.6
1-3
0.9
1.1
2.7
2.6
3-9
4.3
4.9
3.4
7.4
2.4
7-2
3.6
5.7
4.5
5.1
1.1
1.0
1.4
1.6
1.5
1.3
4.8
1.1
3.4
1.4
1.9
1.4
2.2
3.2
1.1
2.3
5.1
2.J
September
ac-ft
83
48
78
94
143
86
274
87
180
100
190
132
543
289
355
553
994
514
2,020
438
1,830
560
1,610
1,230
333
" 172
207
300
581
278
1,150
212
1,000
309
729
402
72
233
286-
-131
%
0.6
0.3
0.6
0.4
0.6
0.4
0.7
0.5
0.5
0.5
0.4
0.3
0.5
3.9
2.8
3.b
3.0
3.5
3.2
4.9
2.3
4.5
2.9
3.6
3.8
3-7
1.4
0.8
1.1
0.7
0.9
0.9
1.6
0.7
1.4
1.0
1.0
0.7
1.1
0.1
0.6
0.3
4.1
2.0
Total
ac-ft
12,818
17,354
14,004
22,462
25,670
20,160
39,290
16,440
36,380
19,290
46,990
37,930
13,855
10, 307
9,940
lB,320
28,760
l6/o4o
40,890
19, 180
40, 240
19,360
44,840
32,390
24,080
22,426
18,990
43,030
63,630
30,420
73,380
29,800
69,390
30,040
75,240
55,120
50,040
40,924
6,840
6,570 -
Provisional data"
-------
TABLE E-5
RAINFALL-RUMOFF COEFFICIEWTS FOR CONTINUOUSLY
GAGED STREAMS IN THE LAKE TAHOE BASIN
TROUT CREEK
Water
Year
60-61
61-62
62-63
63-64
64-65
65-66
66-67
67-68
68 -6y
69-70
Precipitation
Factor
0.8l
1.00
1.52
0.84
1-71
0.79
1.50
0.82
1-75
1.22
Calculated Precipitation
Inches
27
33
50
28
57
26
50
27
58
40
Acre Feet
51,900
64,100
97,4oo
53,800
109,600
50,600
96, 100
52, 600
112,200
70,200
Runoff
Inches
5
10
15
8
21
10
21
10
23
16
Acre Feet
9,9^0
18,320
28,760
16,040
40, 890
19, 180
4o,24o
19,360
44,840
32,390
Rf-Ro.
Coef f
0.19
0.29
0.30
0.30
0.37
0.38
0.42
0.37
0.40
0.4l
Average 0-35
UPPER TRUCKEE
60-61
61-62
62-63
63-64
64-65
65-66
66-67
67-68
68-69
69-70
0.8l
1.00
1.52
0.84
1-71
0-79
1.50
0.82
1-75
1.22
4i
50
77
42
86
40
76
4i
88
61
70,700
87,4oo
132,800
73,400
149,300
69, ooo
131,000
71,600
153,000
106, 600
11
25
37
17
42
17
40
17
43
37
18, 980
43,030
63,630
30,420
73,380
29,800
69,360
30,040
75,240
55,120
0.27
0.49
0.48
0.4i
0.49
0.43
0-53
0.42
0.49
0.52
Average 0.47
BLACKWOOD CREEK
60-61
61-62
62-63
63-64
64-65
65-66
66-67
67-68
68-69
69-70
0.8l
1.00
1.52
0.84
1.71
0.79
1.50
0.82
1-75
1.22
52
64
97
53
109
50
96
52
ill
78
32,000
39,600
60,100
33,200
67,600
31,300
59,300
32,4oo
69,200
48,300
23
37
42
32
63
27
58
31
76
62
i4,oio
22,460
25,670
20,160
39,290
16, 440
36,380
19,290
46,990
37,930
0.44
0-57
0.43
0.61
0.58
0.53
0.61
0.60
0.68
0.79
Average 0-59
TAYLOR CHEEK
68-69
69-70
1-75
1.22
110
77
99,600
69,400
55
45
50,o4o
4o, 924
0.50
0.59
Average 0-54
INCLINE CREEK
69-70
1.22
45
15,500
19
6,84o
0.44
THIRD CREEK
69-70
1.22
50
16,400
20
6,570
0.4o
-------
1
Accession Number
w
5
/p Subject Fit'lrl &. Group
05C
SELECTED WATER RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
Organization
South Lake Tahoe, California
Title
EUTROPHICATION OF SURFACE WATERS LAKE TAHOE
1Q Author(s)
Prr
G.L.
D.B.
McGauhey
Dug an
Porcella
16
21
Project Designation
EPA, WQO Grant No.
16010 DSW
Note
22
Citation
23
Descriptors (Starred First)
*Eutrophication, ^Aquatic Productivity, ^Growth Rates, *Bioassay,
Water Quality, Limnology, Water Pollution Sources, Cycling Nutrients
25
Identifiers (Starred First)
*Lake Tahoe, *Pilot Pond Bioassays, *Land Use,
Nutrient Yield Relationships, Lake Tahoe Area Council
27
Abstract A study of the factors leading to the eutrophication of surface waters, with
:ial emphasis on Lake Tahoe, was conducted over a 5-year period (1966-'7l). A survey
-6f>e
of the nutrients and other chemical constituents was made of surface waters from developed
and undeveloped land areas, sewage effluents, seepage from septic tank percolation systems
and refuse fills, drainage from swamps, precipitation, and Lake Tahoe water. Also, the
algal growth stimulating potential of these sources was made by flask bioassay, utilizing
the alga S_. gracile as a test organism. Continuous flow assays of the biomass of in-
digenous Lake organisms produced by various concentrations of sewage effluent were made
in ponds simulating the shallow portions of the Lake. Other sources of nutrients proved
too dilute to justify pond assays, but flask assays and chemical analyses were made for
over 2 years on 3 major creeks. On 28 other creeks quality was monitored by chemical
analysis. It was concluded that Lake Tahoe is nitrogen sensitive. Creeks draining de-
veloped land carried twice as much nitrogen as those draining undisturbed watersheds.
During active development periods this ratio rose as high as 10:1. The surface streams
plus precipitation contained twice the concentration of N in Lake Tahoe. Exporting all
sewage in the basin would probably remove 70% total N. However, the 30% over present
lake concentration contributed by streams and precipitation on the lake surface is equi-
valent to the secondary sewage effluent of more than 33,000 people, when the concentra-
tion of N in the lake is taken as a baseline value. Recommendations are made for pro-
tection of the shallows and for evaluating the effect of influent sediments.
Abstractor
WR: 1 02
WR5I C
P
(REV
. H.
JULY
McGauhey
Inxti tul ion
1 969) SEND, WITH CO
University
of
California
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON, D. C, 20240
1 ON CENT ER
ftU.S. GOVERNMENT PRINTING OFFICE: 1972 484-483/62 l.j
------- |