WATER QUALITY CONDITIONS
GRAND LAKE, SHADOW MOUNTAIN LAKE, LAKE GRANBY
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ENVIRONMENTAL PROTECTION AGENCY
WATER QUALITY OFFICE
PACIFIC SOUTHWEST REGION
SAN FRANCISCO, CALIFORNIA
CLEA
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DECEMBER 197O
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WATER QUALITY CONDITIONS
in
GRAND LAKE, SHADOW MOUNTAIN LAKE, LAKE GRANBY
ENVIRONMENTAL PROTECTION AGENCY
Water Quality Office
Pacific Southwest Region
San Francisco, California
December 1970
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TABLE OF CONTENTS
Chapter Page
TABLES ii
FIGURES iii
I. INTRODUCTION 1
II. HISTORY AND STATEMENT OF THE PROBLEM 4
III. OBJECTIVES 7
IV. SUMMARY AND CONCLUSIONS 8
V. RECOMMENDATIONS 13
VI. DESCRIPTION OF STUDY AREA 15
VII. METHOD OF SURVEY 21
VIII. DISCUSSION OF FINDINGS 25
EXISTING WATER QUALITY IN THE LAKES 26
EFFECTS OF NATURAL INFLOWS UPON THE WATER
QUALITY OF THE LAKES 38
EFFECTS OF WASTEWATER DISCHARGES UPON NUTRIENT
LEVELS IN THE LAKES 40
BIBLIOGRAPHY 45
APPENDIX: A: PHYSICAL AND CHEMICAL DATA FOR LAKE
STATIONS 46
B: COLORADO WATER QUALITY STANDARDS 50
C: GLOSSARY 57
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TABLES
No. Title
I. Annual Operations Summary, Colorado-Big Thompson
Project 17
II. Average Monthly Summaries, 1953-68, Colorado-Big
Thompson Project 18
III. Sampling Station Locations, Sampling Dates and Types . . 23
IV. Summary of Nutrient Concentrations, Grand Lake,
Shadow Mountain Lake, Lake Granby. 27
V. Physical Measurements at Selected Lake Stations 30
VI. Sedgwick-Rafter Analyses of Plankton Samples 34
VII. Net Plankton Sample Analyses 36
VIII. Flow and Nutrient Concentrations Measured at Tributary
Stations 39
IX. Flow and Nutrient Concentrations Measured in the Grand
Lake Sewage Treatment Plant Outfall, Station 1-16. ... 41
X. Measured Nutrient Input (Lbs/Day) to the Lakes from
Natural and Wastewater Flows 42
A-l. Physical and Chemical Data for Lake Stations 47
11
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FIGURES
No. Title Page
1 Grand Lake, Shadow Mountain Lake, Lake Granby
Study Area 2
Average Monthly Inflow and Outflow-Grand Lake, Shadow
Mountain Lake and Lake Granby 19
Dissolved Oxygen and Temperature Profiles at Selected
Stations 29
iii
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I. INTRODUCTION
This survey was carried out under the provisions of Section 1(3)
and (5) of Executive Order 11288, "Prevention, Control and Abatement of
Water Pollution by Federal Activities," which states:
"Pollution caused by all other operations of the Federal
Government, such as water resources projects and operations
under Federal loans, grants, or contracts, shall be reduced to
the lowest level practicable," and "The Secretary of the Interior
shall, in administering the Federal Water Pollution Control Act,
as amended, provide technical advice and assistance to the heads
of other departments, agencies, and establishments in connection
with their duties and responsibilities under this order,"
respectively.
The Superintendent, Rocky Mountain National Park, Midwest Region,
National Park Service, in a letter dated April 19, 1968, requested the
assistance of the Federal Water Pollution Control Administration to
determine the measures necessary to prevent the pollution of Lake Granby,
Shadow Mountain Lake and Grand Lake (Figure 1). Shadow Mountain Lake
and Lake Granby are within the Shadow Mountain National Recreation Area
which is part of his jurisdiction. However, the survey included all
three lakes since their water quality is interdependent.
In response to this request, the Colorado River-Bonnevilie Basins
Office, Federal Water Pollution Control Administration, conducted a
preliminary survey from August 28-September 6, 1969, of Shadow Mountain
Lake, Grand Lake, Lake Granby and their tributaries.
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SCALE IN MILES
Figure I. Grand Lake, Shadow Mountain Lake, Lake Cranbv Study Area
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Acknowledgments
Principal Authors: Christopher M. Timm
Charles M. Seeley
We acknowledge the assistance provided by personnel of the National
Park Service and the Bureau of Reclamation during this survey.
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II. HISTORY AND STATEMENT OF THE PROBLEM
The establishment of the Rocky Mountain National Park in 1915 began
the development of this important recreational area. The proximity of
Grand Lake, which is the largest natural body of water in Colorado, to
the National Park made the region around the lake a popular summer home
and resort area. Then, in the late 1940's, the U. S. Bureau of Recla-
mation, as part of the Colorado-Big Thompson Project, constructed Granby
Dam and Shadow Mountain Dam forming Lake Granby and Shadow Mountain Lake
respectively. The primary purpose for the construction of these dams
was to supply irrigation water for eastern Colorado. Today, the water
of these lakes serve myriad purposes on both sides of the Rockies such
as power production, public water supplies, fishing, boating, and body
contact sports. The three lakes and the surrounding area on the western
slope have become one of the most popular recreational spots in Colorado
and are visited by tens of thousands of people annually.
The sewage treatment systems that serve these thousands of visitors
are primarily pit or vault toilets or septic tanks. There are two collec-
tion and treatment systems in the area. The Shadow Mountain Government
Camp is sewered and treatment is provided by septic tanks, subsurface
contact filters and chlorination. This system was constructed in 1939
and enlarged in 1949. The effluent is discharged directly into Shadow
Mountain Lake. Part of the Community of Grand Lake is served by a
trickling filter plant built in 1951 which discharges to Shadow Mountain
Lake. The population served by this plant varies from approximately 150
people during the winter to 4,000 people during the summer (recreation
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season). The remainder of the community is served by individual dis-
posal systems.
Partially treated wastewater has been discharged into Shadow
Mountain Lake for more than 20 years, but evidence of pollution has not
become apparent until recent years. On October 2, 1967, the Public
Health Service consultant to the National Park Service surveyed Shadow
Mountain Lake at the request of the National Park Service. This survey
resulted from the complaints of local residents and businessmen located
on the west side of Shadow Mountain Lake. The nature of the complaints
were varied but were along the following general lines:
1. Large accumulations of persistent foam.
2. Algae formations along the shoreline and on boats anchored in
docking areas.
3. Floating solids and sludge deposits.
4. Turbidity caused by sludge in water. (This was subsequently
identified as algae bloom.)
The observed conditions in Shadow Mountain Lake were:
1. Light to moderate algae growth along the west shoreline from the
Headquarters area to Grand Lake.
2. Some small accumulations of persistent foam at various points
along the shoreline.
3. Moderate algae bloom along the west shoreline.
4. Generally heavy turbidity in the western portions of the Lake
apparently caused by sludge accumulations.
From these observations, the Public Health Service consultant in a
letter to the Superintendent, Rocky Mountain National Park, dated October 5,
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1967, stated that, "Results of the investigation, while not conclusive
due to lack of quantitative evidence, do indicate the presence of domes-
tic pollution of sufficient strength to create public health hazards."
In May 1968, the Colorado Water Pollution Control Commission
adopted general standards applicable to all waters of the state. In
addition, the three lakes have been classified as suitable for potable
water supplies (Class A) and for cold water fisheries (Class B^) . The
specific standards for these uses include dissolved oxygen not less than
6.0 mg/1, pH between 6.5 and 8.5, and temperature not to exceed 70°F
(21.1°C). The complete water quality standards for these waters are
reproduced in Appendix B.
The Secretary of the Interior in approving the Colorado Water Quality
Standards requested that the three lakes also be classified for body
contact sports (63) based upon the existing recreational uses. The
Commission has conducted some sampling of the lakes over the past two
years to obtain background data for adding this classification. The
addition of a Bo classification would make the bacteriological criteria
for the lakes more stringent. The specific standards applicable to
recreational waters classified for body contact sports are also repro-
duced in Appendix B.
The increasing recreational use of this area, the occurrence of
nuisance algae growths, and the apparent pollution of these lakes brought
about the National Park Service request to the Federal Water Pollution
Control Administration for assistance in defining the effects of waste-
water on these lakes and in developing the necessary corrective measures.
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III. OBJECTIVES
The primary objective of this survey was to develop the water pollu-
tion control measures necessary to protect and preserve the recreational
and other uses of these lakes. To accomplish this, the following specific
objectives were pursued:
1. To determine the existing physical, chemical, and biological
conditions in the lakes and tributaries.
2. To determine the nutrient inputs to the lakes from natural
runoff.
3. To locate and identify the wastewater inflows to the lakes and
measure their nutrient loads.
4. To evaluate the pollution potential from increased recreational
use in the surrounding area.
5. To recommend the actions necessary to abate the present pollution
and protect the lakes from accelerated eutrophication.
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IV. SUMMARY AND CONCLUSIONS
1. The laboratory analyses of samples collected from Grand Lake, Shadow
Mountain Lake, and Lake Granby show that the inorganic nitrogen con-
centrations were uniform throughout the lakes and averaged 0.107 mgN/1
over the survey period. This concentration is approximately one-third
of that considered necessary to initiate an algae bloom (0.30 mgN/1).
The orthophosphate concentration in the three lakes averaged 0.0255
mgP/1 and ranged from 0.0084 mgP/1 in Grand Lake to 0.0526 mgP/1 in
Shadow Mountain Lake. This average concentration greatly exceeds the
minimum level of orthophosphate considered by authorities in the field
as necessary to sustain an algae "bloom" (0.010 mgP/1). In addition,
the orthophosphate concentration at the bottom of Lake Granby ranged
from two to thirteen times greater than surface concentrations indica-
ting the possibility that anaerobic respiration may take place in the
benthic regions.
2. The average inorganic nitrogen, orthophosphate, and total soluble
phosphorus concentrations in the natural runoff from the surrounding
watershed were 0.07 mgN/1, 0.007 mgP/1, and 0.064 mgP/1 respectively.
The inorganic nitrogen and orthophosphate concentrations are much lower
than the suggested limits of 0.30 mgN/1, and 0.010 mgP/1 respectively,
but the total soluble phosphorus concentrations exceeded the suggested
limit of 0.05 mgP/1.
3. The domestic wastewater sources in the three lakes area are the Grand
Lake wastewater treatment facility, the Shadow Mountain Government Camp
wastewater treatment facility and the numerous individual subsurface
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disposal systems serving homes and businesses along the shores. Efflu-
ents from the two treatment facilities are the largest point sources of
nutrients entering the lakes. Analyses of the Grand Lake wastewater
treatment facility effluent, the largest wastewater discharge, showed
average inorganic nitrogen, orthophosphate and total soluble phosphorus
concentrations of 13.43 mgN/1, 5,21 mgP/1 and 6.14 mgP/1 respectively.
In terms of total load, this plant provided only 0.28 percent of the
total inflow to the lakes but supplies 36.0 percent of the inorganic
nitrogen, 68 percent of the orthophosphate and 21.5 percent of total
soluble phosphorus loads to the lakes during this survey. Therefore,
advanced waste treatment methods including at least 80 percent ortho-
phosphate removal, wastewater export, or total containment of effluents
in ponds will be required to preserve the present water quality and re-
duce the nutrient concentrations in the lakes.
4. The concentration of orthophosphate, the phosphorus form most readily
available for biological growth, is sufficiently high that any one or
all three of the lakes could sustain nuisance algae blooms. Waste-
waters contributed the major portion of orthophosphate to the lakes
with the Grand Lake wastewater treatment facility alone contributing
68 percent of the measured orthophosphate load. It is estimated, based
upon data obtained in this survey, that the combined wastewater flows
contribute more than 80 percent of the annual orthophosphate load. The
low inorganic nitrogen concentrations existing in the lakes and inflows
and the presence of Aphanizomenon flos-aquae and Anabaena sp., both
atmospheric nitrogen fixers, indicate that the lake waters are nitrogen
deficient and the phytoplankton growth is nitrogen limited.
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5. Temperature measurements showed that Lake Granby and Grand Lake had
thermally stratified layers although thermoclines, as defined in the
glossary, were not in evidence. Shadow Mountain Lake was generally
isothermal as expected because of its shallow depth and the effects
of mixing.
6. The dissolved oxygen concentration in the near surface waters of all
three lakes exceeded the 6.0 mg/1 standard for cold water fisheries at
all stations except for Station L-5 on Shadow Mountain Lake. The dis-
solved oxygen concentration at this sampling station, which is located
near the west shore of the Lake between two marinas, was 5.6 and 5.2
mg/1 on September 1 and 3, 1969, respectively. The dissolved oxygen
concentrations were 3.0 mg/1 or greater throughout the depths of all
three lakes. Grand Lake and Shadow Mountain Lake had dissolved oxygen
profiles approximating an orthograde pattern, but the profile in Lake
Granby approached a clinograde pattern with concentrations of less than
6.0.mg/1 in the hypolimnion. This oxygen deficit is caused by a natural
deposition of oxidizable organic material in Lake Granby during spring
runoff. Because much of the organic material is probably either suspended
in natural .runoff or photosynthesized in the lakes, the depletion of dis-
solved oxygen in the hypolimnion of Lake Granby is not readily correct-
able and will worsen with time. There is no data available which re-
flects the effects of this organic material upon the dissolved oxygen
concentration of Lake Granby during other periods of the year. Since
this lake is stocked regularly with game fish, the combined effects
of the organic matter and ice cover on the dissolved oxygen concen-
trations and game fishery should be investigated.
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11 .
7. The Secchi Disk transparency measurements indicate that the euphotic
zone extended through the epilimnion into or below the zone of greatest
temperature change in the three lakes. In addition, the Sedgwick-Rafter
analyses of plankton samples did not show any variation between total
plankton counts with depth. This indicates that the entire epilimnion
receives sufficient light energy to support photosynthesis. Total
phytoplankton analyses by the Sedgwick-Rafter method gave maximum counts
of 527 organisms/ml in Grand Lake, 272 organisms/ml in Shadow Mountain
Lake, and 221 organisms/ml in Lake Granby. Eight of sixteen phyto-
plankton samples had less than 200 organisms/ml which indicate low
to moderate biological productivity in all the lakes. Numerically,
Dinobryon sp., a yellow-green algae which causes taste and odor problems
when present in high concentrations, was the most abundant organism.
The blue-green algae Aphanizomenon flos-aquae which is capable of fixing
atmospheric nitrogen was discernable in the surface waters of all three
lakes and was the predominant organism recovered in net plankton samples.
8. The biological results showed no evidence of an algal "bloom" during this
survey. On the basis of dissolved oxygen and nutrient concentrations,
depth of the euphotic zone, and plankton populations, none of the three
lakes could be considered eutrophic. The productivity of Granby and
Grand Lakes is such that their classifications are between oligotrophic
and mesotrophic. Shadow Mountain Lake was the most productive and
could be classed as a mesotrophic lake.
9. The existing water quality of the three lakes is equal to or better than
the standards established for the classified uses of the three lakes ex-
cept that the dissolved oxygen concentrations in the hypolimnion of Lake
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Granby were less than the established standards of 6.0 mg/1. It is
possible that natural sources of organic material are the major cause
of the depressed dissolved oxygen. The limited scope and duration of
the study, however, did not permit a complete evaluation of this situ-
ation, and further study is indicated to provide a basis for remedial
action.
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V. RECOMMENDATIONS
In order to protect and/or enhance water quality and water uses of
Grand Lake, Shadow Mountain Lake, and Lake Granby, it is recommended:
1. That the classification, 63, Body Contact Recreation, be added
to the water uses established for the three lakes.
2. That the Colorado Water Pollution Control Commission establish
water quality standards for the three lakes and their tribu-
taries containing nutrient criteria and required waste treatment
and other control measures which will not only prevent further
enrichment of these waters but enhance their quality.
3. That immediate action be taken to control and treat all wastewaters
in the three-lakes watershed by either, (a) total containment,
(b) advanced waste treatment which will limit the flow weighted
inorganic nitrogen, orthophosphate and total phosphorus concen-
trations of the combined natural and wastewater inflows to
the lakes of less than 0.30 mgN/1, 0.010 mgP/1 and 0.050 mgP/1,
respectively, or (c) secondary waste treatment with discharge to
the Colorado River below Lake Granby.
4. That the Federal agencies immediately implement recommendation
number 3 in order to control the contribution to water pollution
from their activities or facilities. In conjunction with this,
the Federal agencies must cooperate with and assist the local
government in the development and implementation of an adequate
regional wastewater treatment system.
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5. That a comprehensive plan for water pollution control and quality
management be developed for the three-lakes watershed. This
plan should include a regional wastewater collection, treatment
and disposal system to be fully implemented no later than 1975.
The plan must also provide the controls necessary to insure
that future development will not degrade the water quality of
the three lakes.
6. That the water quality of the lakes, natural inflow and waste
sources be monitored periodically to determine seasonal changes
in nutrient loads, and to evaluate the effectiveness of any
improvements or additions made to the present wastewater treat-
ment facilities. The National Park Service, the Bureau of
Reclamation, and the State of Colorado should make arrangements
to accomplish this monitoring.
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VI. DESCRIPTION OF STUDY AREA
Lake Granby and Shadow Mountain Lake are manmade reservoirs linked
by channels to Grand Lake, the largest natural body of water in Colorado.
The three lakes are located on the headwaters of the Colorado River
(Figure 1) .
Grand Lake is a glacial lake naturally impounded by the terminal
moraines of the glaciers that created the present valleys of the North
Inlet and East Inlet (5). It has steep sides along the northern and
eastern shores and is shallow along the southern and western shores formed
by the terminal moraines. The lake has a maximum depth of greater than
200 feet (69.9M), a surface area of 504 acres (2 sq.Km), and a normal
water surface elevation of 8367 feet (2548M) (11).
Shadow Mountain Lake is impounded by a low dam across the Colorado
River below Grand Lake and provides passage and flow regulation for water
being diverted to the eastern slope of the Colorado Rockies through the
Alva B. Adams Tunnel. This lake lies wholly within the Shadow Mountain
National Recreation Area with the eastern shore forming the boundary for
the Rocky Mountain National Park. Most of the land along the west and
north shores is privately owned and has been developed as summer home
sites, resorts and marinas. Shadow Mountain Lake has a maximum capacity
of 18,359 acre-feet (22 .6x10^) , an active storage of 1850 acre-feet
(2.3x10 M ), and a maximum surface area of 1852 acres (7.5 sq.Km.). The
average and maximum depths are 10 (3M.) and 37 feet (11.3M.), respectively.
The maximum water surface elevation is 8367 feet (2548M) above sea level
and the maximum drawdown head is 20 feet (6.1M.). A check structure is
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located between Shadow Mountain and Grand Lake so the water surface eleva-
tion of Shadow Mountain Lake can be lowered without affecting Grand Lake.
However, the usual operating practice is to maintain Shadow Mountain Lake
at the same elevation as Grand Lake. (11)
Lake Granby, which stores the majority of the water supply for the
Colorado-Big Thompson Project, is formed by Granby Dam and four dikes which
impound the waters of the Colorado River and the water pumped from Willow
Creek Reservoir. This lake lies wholly within the Shadow Mountain National
Recreation Area and forms part of the boundary for the Rocky Mountain
National Park. Most of the establishments along the shores of Lake Granby
are boat launching areas, parks, and campgrounds for the summer tourists.
Lake Granby has a maximum capacity of 540,000 acre-feet (666xlOT4 ), and an
active storage of 466,000 acre-feet (575xl0^r). The lake covers a surface
area of 7,260 acres (29.4 sq.Km.) at the maximum water surface elevation
of 8,280 feet (2521M) above mean sea-level. The average and maximum depths
are 74 (22.5M) and 200 feet (60.9M), respectively. The outlet at the face
of Granby Dam is set between elevations 8150 (2481.7M) and 8190 feet (2493.8M),
but active storage is considered to extend downward to elevation 8186 feet
(2492.6M) providing a maximum drawdown head of 94 feet (28.6M) (11).
The annual operation summary and average monthly summaries for the
Colorado-Big Thompson Project are shown in Tables I and II respectively.
Analysis of the average monthly inflows and outflows, which are plotted on
Figure 2, shows two general flow patterns through the lakes. Sixty percent
of the average annual inflow generally occurs in May and June. The average
diversion through the Adams Tunnel during these same months was about 24,900
6 ^
acre-feet (30.7x10 M ). The basic flow pattern is from Grand Lake and
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TABLE I Annual Operations Summary. Western Slope Features
of the Colorado-Big Thompson Proiect
End of Year Storage
Year
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
Total
Inflow
AFl'
200,756
147,918
204,082
266,737
446,151
243,797
251,832
287,785
297,763
317,878
193,674
221,953
375,316
166,014
283,981
248,630
Lake
Granby
AF!/
427,335
230,050
168,436
188,398
418,061
387,444
352,567
365,772
460,852
437,977
306,412
190,117
346,635
214,714
236,878
259,640
Shadow
Mtn.Lake
AFl/
18,149
18,111
18,111
17,780
17,542
17,725
17,578
17,707
17,854
17,872
17,872
17,670
17,651
17,633
17,651
17,578
1953-1968
Pumped to
Shadow
Mtn.Lake
AFi/
164,919
278,644
195,386
188,783
161,792
228,916
214,261
207,912
130,025
173,072
239,452
253,022
141,021
221,362
196,016
167,418
0 u t f
Adams
Tunnel
AF-i'
205,247
320,794
237,108
220,735
188,541
243,416
257,920
244,871
173,562
237,105
297,426
310,074
188,371
271,091
232,666
196,213
lows
Colorado
River
AF!/
25,767
25,738
25,712
25,745
25,573
25,218
25,660
25,683
24,426
98,931
24,617
27,074
28,846
24,971
28,064
28,673
Seepage
AF!/
6,701
3,446
854
726
2,594
5,588
3,906
3,895
3,756
5,419
3,178
1,302
1,600
1,892
1,069
1,075
AVG.
259,642
311,956
17,780
197,625
239,032
30,669
2,938
I/ To convert to M multiply by 1233.5.
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TABLE II Average Monthly Summaries. Western Slope Features
of the Colorado -Big Thompson Proiect
End of Month Storage
Month
Jan.
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Total
Inflow
AF!/
3,725
3,206
3,700
14,052
64,574
97,246
36,848
12,643
7,815
6,655
5,093
4,085
Lake
Granby
AF!/
295,782
282,662
252,796
253,582
297,200
380,158
392,470
381,529
368,546
352,906
334,141
311,956
Shadow
Mtn. Lake
AF!/
17,827
17,819
17,869
17,465
17,451
17,527
17,673
17,706
17,715
17,689
17,739
17,780
1953-1968
Pumped to
Shadow
Mtn. Lake
AF!/
24,275
21,838
23,312
13,240
3,838
1,386
11,152
17,346
17,834
18,150
21,247
24,007
Outflows
Adams
Tunnel
AF!/
25,070
22,512
24,304
17,015
16,072
8,781
17,558
20,809
19,078
20,719
22,332
24,782
Colorado
River
AF!/
1,212
1,110
1,614
2,614
4,933
5,274
6,564
2,432
1,233
1,288
1,187
1,208
Seepage
AF!/
258
213
205
178
171
199
276
312
300
300
274
252
I/ To convert to M3 multiply by 1233.5.
00
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19
100
95
90
85
80
75
70
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TOTAL OUTFLOW
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JAN FEB MAR APR MAY JUN JUL ' AUG* SEP* OCT* NOV DEC
MONTHS
Figure 2. Average Monthly Inflow & Outflow, Grand Lake,
Shadow Mountain Lake & Lake Cranby
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Shadow Mountain Lake into Lake Granby during this time.
During the period August through April, the flow through the Adams
Tunnel greatly exceeds the areal runoff into the lakes and water must be
pumped from Lake Granby for diversion to the eastern slope. During this
time, the flow pattern can generally be described as being from Lake Granby
through Shadow Mountain Lake and Grand Lake into the Adams Tunnel.
To protect the existing fisheries in the Colorado River, the U. S.
Bureau of Reclamation maintains minimum flow below both Shadow Mountain and
Granby Dams. The minimum releases from Shadow Mountain Dam are 25 cfs
3 3
(.7 M /Sec) during October through April and 50 cfs (1.4 M /Sec) during
May through September. The minimum releases from Granby Dam are 20 cfs
(.6M3/Sec) during September through April, 75 cfs (2.1 M3/Sec) during May
through July, and 40 cfs (l.lM3/Sec) during August.
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VII. METHODS OF SURVEY
The survey of existing water quality conditions was accomplished in
two phases. The physical and chemical survey was conducted from August 28,
to September 3, and the biological survey on September 5 and 6, 1969.
During the physical and chemical survey, 14 stations on the three lakes
and 12 stations on tributaries and waste sources were sampled to estab-
lish the existing physical and chemical quality parameters (Figure 1) .
The Grand Lake wastewater treatment facility effluent (1-16) and
Shadow Mountain Reservoir near the channel to Grand Lake (L-4) were sampled
daily and the Grand Lake Stations (L-l, L-2, L-3) were sampled every other
day. All other stations were sampled as shown in Table III. Water quality
samples and measurements were taken at mid-depth from all inflow and out-
flows. At the lake stations, water quality samples and measurements were
taken at the surface and the bottom except where the total depth was 20
feet (6.1M) or less. In the latter cases, water quality samples and
measurements were taken at mid-depth.
Temperature, conductivity, dissolved oxygen concentration and pH were
measured at each point where a sample was collected for nutrient analyses.
The samples were analyzed using standard procedures:
1. Nitrate - soluble inorganic nitrogen.
2. Ammonia - evidence of organic pollution.
3. Total Kjeldahl nitrogen - total organic nitrogen.
4. Orthophosphates - Phosphorus available for instant biological use.
5. Total soluble phosphates - total phosphorus available for biolo-
gical use.
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These analyses were performed by the Services Branch, Colorado River-
Bonneville Basins Office, Federal Water Pollution Control Administration.
During the biological survey, nine lake stations, three on each lake,
were sampled to establish the biological quality of the lakes. During
the biological sampling, light penetration was measured using the Secchi
Disk; water samples were collected for phytoplankton analysis; and net
drags or vertical hauls were made at selected stations for a qualitative
phytoplankton analysis. In addition, the temperature and dissolved oxygen
concentrations at various depths were measured in all three lakes. The
biological analyses were performed by personnel of the Services Branch,
California-Nevada Basins Office, Federal Water Pollution Control Admini-
stration.
The survey areas and sampling station locations are depicted in
Figure 1. The location, dates and types of sampling for each station are
listed in Table III.
-------
23
TABLE III Station Location, Dates and Type of Samples Collected, 1969
No.
1-1
1-2
1-3
1-4
1-5
1-6
1-7
1-9
1-10
1-11
>••
1-13
I-16I/
L-l
L-2
L-3
STATION
Location
Arapaho Creek at Bridge
Roaring Fork at Mount
Twin Creek at Mouth
Columbine Creek at Mouth
East Inlet at Mouth
North Inlet at Grand Ave .
Bridge
Little Columbine Creek at
Gaging Station
Colorado River at Gaging
Station near Mouth
Soda Creek at Hwy 34 Crossing
Stillwater Creek at Gaging
Station
Colorado River below Lake
Granby at Bridge
Grand Lake Wastewater Treat-
ment Facility Outlet
Grand Lake about 100 yards
east of west portal
Grand Lake between the two
marinas on Grand Beach
Grand Lake about 50 yards
out from house with slide
DATES AND TYPE OF SAMPLES COLLECTED
Physical
Aug. 28
Aug. 28
Aug. 28
Aug. 28
Aug. 28
Aug. 28
Sept. 2
Aug. 28
Aug. 28
Sept. 2
Aug. 28
Aug. 28
Sept. 2
Aug. 28
Aug. 28
through
Sept. 3
Aug. 28&30
Sept. 1&3
Aug. 28&30
Sept. 1&3
Aug. 28&30
Sept. 1&3
Chemical
Aug. 28
Aug. 28
Aug. 28
Aug. 28
Aug. 28
Aug. 28
Sept. 2
Aug. 28
Aug. 28
Sept. 2
Aug. 28
Aug. 28
Sept. 2
Aug. 28
Aug. 28
through
Sept. 3
Aug. 28&30
Sept. 1&3
Aug. 28&30
Sept. 1&3
Aug. 28&30
Sept. 1&3
Biological
Sept. 6
Sept. 6
Sept. 6
I/ Bacteriological Quality determined by Colorado State Health Department (2)
-------
24
TABLE III (Continued) Station Location, Dates and Type of Samples Collected
1969
No.
L-4
L-5
L-6i/
L-7
L-&1/
L-9
L-10
L-ll
L-12^
L-131/
L-lO/
STATION
Location
Shadow Mountain Lake between
entrance to Grand Lake
channel and marina.
Shadow Mountain Lake between
Lake Kove and Shadow Mountain
Marina.
Shadow Mountain Lake at
center of lake ,
Shadow Mountain Lake about
50 yards from east shore.
Shadow Mountain Lake at
National Park Service boat
dock.
Lake Granby 100 yards out from
Stillwater Campground boat
launch.
Lake Granby in Rainbow Bay
midway between boat ramp and
Lochleven Cove.
Lake Granby at Center
Lake Granby 300 yards north
of Twin Creek in Grand Bay.
Lake Granby about 400 yards
south of Twin Pines Point.
Lake Granby in the middle of
Arapaho Bay .
DATES AND TYPE OF SAMPLES COLLECTED
Phys ical
Aug. 28
through
Sept. 3
Aug. 29
Sept. 1&3
Aug. 29
Sept. 2
Aug. 29
Sept. 2
Aug. 29&30
Aug. 29
Sept. 2
Aug. 29
Sept. 2
Aug. 29
Sept. 2
Aug. 29
Sept. 2
Aug. 29
Aug. 29
Sept. 2
Chemical
Aug. 28
through
Sept. 3
Aug. 29
Sept. 1&3
Aug. 29
Sept. 2
Aug. 29
Sept. 2
Aug. 29&30
Aug. 29
Sept. 2
Aug. 29
Sept. 2
Aug. 29
Sept. 2
Aug. 29
Sept. 2
Aug. 29
Aug. 29
Sept. 2
Biological
Sept. 5
Sept. 5
Sept. 5
Sept. 6
Sept. 6
Sept. 6
\l Bacteriological Quality determined by Colorado State Health Department (2)
-------
25
V. DISCUSSION OF FINDINGS
The intent of this survey was to evaluate the existing water quality
conditions, define the effects of wastewaters, and recommend remedial
measures to protect the lakes. To accomplish this, the analytical results
of this survey were compared with established water quality standards where
applicable and with the recommended limits for those parameters for which
standards have not been set.
With the exception of nutrient concentrations, the Colorado Water
Quality Standards established limits for all the physical and chemical
parameters measured during this survey. The limiting values for the
former, which are discussed below, are based on previous work reported in
the literature.
Several investigators (3,6) have concluded that concentrations of
inorganic nitrogen exceeding 0.30 mgN/1 in lakes could be expected to
produce nuisance algae blooms, although it has also been shown that many
blue-green algae species, particularly Anabaena and Aphanizomenon, can fix
sufficient amounts of atmospheric nitrogen to sustain high productivity.
For evaluation of the data obtained in this survey, an inorganic nitrogen
limit of 0.30 mgN/1 in Lakes appears reasonable. The limiting value is
also 0.30 mgN/1 for all tributary streams sampled.
Although much has been written about the effects of phosphorus upon
algae growth, the level of phosphorus necessary to sustain a nuisance algae
growth has yet to be quantified. From the results of previous investigations
(6,7,8), it appears that the orthophosphate concentration in a lake must be
limited to 0.01 mgP/1 to prevent algae blooms. With respect to the
-------
26
concentrations in streams, Mackenthun (7) has recommended that the total
soluble phosphorus concentrations be limited to 0.05 mgP/1. However, this
limit is considered applicable only during low-flow conditions and the
average annual orthophosphate concentration in the stream should not exceed
the limit proposed earlier for the lakes.
EXISTING WATER QUALITY IN THE LAKES
Individual results of the nutrient samples collected from the lakes
for analysis are shown in Table A-l in the Appendix. These data have been
summarized and the high, low and average orthophosphate and total soluble
phosphate and inorganic nitrogen concentrations are shown in Table IV.
Comparing the summary of data with the nutrient criteria discussed above,
all three lakes are nitrogen deficient but contain sufficient phosphorus
concentrations to support algae "blooms." In such circumstances, only
those algae species capable of providing their own nitrogen by atmospheric
nitrogen fixation can cause "blooms."
The nutrient levels in Grand Lake (Station L-l, L-2, L-3) and Shadow
Mountain Lake (Station L-4 through L-8) did not vary appreciably with depth.
The only exception is Station L-8 where the inorganic nitrogen, orthophos-
phate and total soluble phosphate concentrations measured on August 29,
1969, were approximately four times the lake averages shown in Table IV.
One possible explanation is that the effluent from the Shadow Mountain
Government Camp wastewater treatment facility may have been flowing
across this sampling station as a density current at the time of sampling.
The samples from Lake Granby showed orthophosphate concentrations two
,»
to thirteen times greater at the lake bottom than at the surface, and
dissolved oxygen content and pH were consistently lower at the lake bottom.
-------
TABLE IV Summary of Nutrient Concentrations - Grand Lake, Shadow Mountain Lake, Lake Granby
Total
Inorganic Nitrogen Orthophosphate Soluble Phosphorus
Grand Lake
Shadow Mountain Lake
Lake Granby
All Three Lakes
High
mgN/1
.12
.62
.29
.62
Low
mgN/1
.06
.07
.06
.06
Avg
mgN/1
.082
.145
.096
.107
High
mgP/1
.0293
.1565
.0880
.1565
Low
mgP/1
.0032
.0064
.0032
.0032
Avg
mgP/1
.0084
.0526
.0154
.0255
High
mgP/1
.109
.254
.111
.254
Low
mgP/1
.013
• .013
.013
.013
Avg
mgP/1
.043
.065
.070
.059
-------
28
From these facts, it would appear that organic decomposition in the
hypolimnion was converting organic phosphate to soluble polyphosphates
and reducing the dissolved oxygen concentration. Since pH generally
(3)
parallels the dissolved oxygen concentration , the hypolimnion may
become acidic during the course of the summer; thereby, increasing the
rate of hydrolysis of polyphosphates to orthophosphates^ ^. Since
these physical phenomena were not present in either Grand Lake or Shadow
Mountain Lake, it is reasonable to assume that Lake Granby has the highest
organic content. This may be the result of either the failure to properly
clear the lake bed prior to impoundment or the transportation of the
organics deposited in the upper lakes into Lake Granby during the spring
runoff period or both.
Although a true thermocline was not found in any of the lakes, both
Grand Lake and Lake Granby have two distinct temperature zones and could
be classified as thermally stratified (Table V, Figure 3). The use of
the terms, epilimnion and hypolimnion, therefore, will be used in dis-
cussing the waters above and below that zone of greatest temperature
change. In Shadow Mountain Lake, the shallow nature of the reservoir,
the mixing due to wind action, and the pumping of colder water from the
depths of Lake Granby into Shadow Mountain Lake prevent thermal stratifi-
cation.
The dissolved oxygen concentrations measured during the first phase
of this survey are shown in Table A-l in the Appendix. Dissolved oxygen
profiles were measured at selected stations during the biological phase
of the survey as shown in Table V and Figure 3. The dissolved oxygen
-------
10
DISSOLVED OXYGEN - MG/L
10 0 5 10 0 5
10
10 0
10
TEMPERATURE - °C
10 20 0 10 20 0 10 20 0 10 20 0 10 20 0 10 20
10
20
30
40
H- 50
^ 60
70
80
90
100
l-l
L-2
1-3
L-11
1-12
LEGEND
DISSOLVED OXYGEN
TEMPERATURE
L-13
GRAND LAKE
LAKE GRANBY
Figure 3. Dissolved Oxvgen and Temperalure Profiles at Selected Stations
-------
TABLE V Physical Measurements at Selected Lake Stations
Station
Number
L-l
L-2
L-3
L-4
L-6
L-8
Date
and Time
Sept. 6
1530
Sept. 6
1715
Sept. 6
1500
Sept. 5
1330
Sept. 5
1245
Sept. 5
1145
Sample . ,
Depth Ft.-'
2
10
20
30
40
50
60
70
80
90
100
2
10
20
30
40
60
80
100
2
10
20
30
0
7
0
16
0
8
Temperature
°C
16.6
16.6
15.0
10.5
8.3
7.8
7.2
6.7
6.0
5.5
5.5
16.0
16.0
13.9
11.6
8.3
7.2
6.1
5.5
15.5
15.5
12.7
9.4
15.0
15.0
15.2
15.0-
15.0
14.5
Dissolved
Oxygen
tng/1
7.6
7.6
7.3
6.6
7.0
7.4
7.6
7.6
6.9
6.4
7.6
7.6
6.6
6.4
7.0
7.6
7.2
7.6
7.6
6.4
6.4
7.6
7.3
7.2
7.7
7.4
7.2
DJD xlOO
Saturation
104
104
97
80
80
84
85
83
74
68
103
103
86
79
80
84
78
102
102
81
81
101
97
97
103
99
95
Secchi Disk . ,
Transp. Ft.— Euphotic Zone Ft.-=-'
13.5 36.4
12.5 33.5
7 Depth of Lake
7.2 Depth of Lake
8.0 Depth of Lake
!_/ To convert to meters, multiply by .3046.
US
o
-------
TABLE V (Continued) Physical Measurements at Selected Lake Stations
Station Date
Number and Time
L-ll Sept. 6
1245
L-12 Sept. 6
1140
L-13 Sept. 6
1020
Sample
Depth Ft.!/
2
10
20
30
40
50
70
80
102
2
10
25
50
2
10
20
30
40
50
60
90
Temperature
°C
19.4
17.7
17.7
17.1
14.4
12.1
8.9
8.3
8.3
18.2
17.7
17.7
11.0
18.2
17.7
18.2
17.7
13.5
12.1
10.5
8.3
Dissolved
Oxygen
mg/1
7.0
7.1
6.4
___
5.0
___
___
4.0
6.8
6.8
6.6
3.0
6.85
6.8
6.75
6.85
4.55
5.0
3.95
D.O.
D.O. Secchioisk
Saturation Transp . Ft.— Euphotic Zone Ft.!'
102
100 12.5 33.5
89
_._
62
___
46
96
97 14.5 39.1
93
36
97
96 17.0 45.9
96
99
58
60
45
_!/ ¥b convert to meters multiply by .3046.
-------
32
profiles in Grand Lake approximate an orthograde rather than a clinograde
pattern with the lowest measured concentration (6.4 mg/1 at 5.5°C and 100
feet) equal to 68 percent of saturation. Percentages as high as this
obtained from the hypolimnion of a thermally stratified lake late in the
summer suggest that the amount of oxidizing organic material is not great
and that Grand Lake is only moderately productive.
In Lake Granby, oxygen depletion in the hypolimnion is more severe.
Dissolved oxygen concentrations as low as 3.0 mg/1 (36 percent saturation)
were found at the 50-foot depth of Station L-12. This suggests that, while
not extreme, the oxygen pattern is more clinograde than orthograde and that
summer-long accumulations of oxygen-demanding organic materials are more
concentrated in Lake Granby than in Grand Lake. In the well-mixed waters of
the epilimnion, the oxygen content remained close to saturation. The absence
of very high values here indicates only a moderate rate of photosynthesis.
In Shadow Mountain Lake, the oxygen concentrations remain uniformly
near saturation values throughout the depths showing that the effects of
the physical processes of atmospheric reaeration and deaeration override
any tendency for oxygen to reach either extreme highs or lows. This is
to be expected in such a shallow exposed lake containing moderately produc-
tive water.
In Grand Lake and Lake Granby the surface dissolved oxygen values
were equal to or greater than 6.0 mg/1, the established dissolved oxygen
standard for Class B^ waters. However, dissolved oxygen concentrations
as low as 5.2 mg/1 were observed at Station L-5 in Shadow Mountain Lake.
Since this station is located on the west side of the lake between two
marinas, it is possible that this dissolved oxygen depletion resulted
-------
33
from the increased recreational use in this area during the Labor Day
weekend.
The depth of light penetration into a lake is of biological impor-
tance since all rooted, suspended, and floating aquatic plants require
light energy for photosynthesis. While light penetration is exceedingly
variable in different lakes, it can generally be stated that higher
quality water permits greater light.penetration.
At the selected lake stations where light penetration was measured
(Table V) , the euphotic zone, which is calculated from the Secchi Disk
transparency measurements, extended through the well mixed upper water
into or below the depths of greatest temperature change. Therefore,
sufficient light existed throughout the epilimnion for photosynthesis.
Shadow Mountain Lake, because of the shallow depths, is entirely within
the euphotic zone. The fact that the depth of light penetration was
greater than 30 feet in all the lakes is indicative of generally high-
quality waters.
Although the blue-green algae, Aphanizomenon flos-aquae, was abun-
dant enough to be discerned visually in the surface water, examination
of the Sedgwick-Rafter analyses of water samples (Table VI) indicates
that the algae "bloom" conditions found during the October 2, 1967,
survey were not present at this time. For this survey, an algae "bloom"
is defined as a count of an individual organism exceeding 500/ml (4).
The maximum density was observed at Station L-3 in Grand Lake where a
count of 527 organisms/ml was recorded at a depth of two feet. Overall,
the productivity of the lakes can be considered low since one-half of the
-------
TABLE VI. Sedgwick-Rafter Analyses of Plankton Samples
Location
HTanrl
T akp
Shadow
Reservoir
Station
& Depth
L-1 9 '
L-i in1
T _0 0 '
T _9 in1
T _9 QO '
L_o 0 1
J > ^
T _Q 1 0 1
T -^ *}o '
L-4, 21
T _f> 9 '
L-8, 2'
L-11,21
L-11,101
L-i i ^n '
T _1 0 01
L-i "^ 9n '
Blue-Green Green
Coccoid Coccoid
______ ^i
______ "\L
------ f>8
------ f>8
______ 17
______ 11Q
______ 170
17
17
17 17
17
______ ^A
Green
Flagellates
f.0
si
SI
QC
--
34
34
34
70/L
QC
1 1 Q
Other
Flaggellates
i r>9
QC
QS
•JA
991
110
OA
17
1 ^6
102
Diatoms
1 7f>
T/,
QS
1 09
(.a
1 O9
110
9fiQ
102
SI
119
85
34
OA
1 7
Total
Plankton
Counts
OAfi
991
oaq
i 70
1 7O
S97
408
Q O*3
136
1 R7
272
153
85
991
1 1 Q
i 70
-------
35
plankton samples had less than 200 organisms/ml, total count. Numerically
the most abundant organism in any sample was Dinobryon sp., a yellow-green
algae which causes taste and odor problems when present in high concen-
trations (9) .
The net plankton sample analyses (Table VII) provide a different
qualitative picture. It is emphasized, however, that net samples are not
quantitative because (1) they are biased toward the larger forms, (2) the
efficiency increases as the meshes become clogged, and (3) the volume
filtered is difficult to control. Notwithstanding these shortcomings,
plankton net samples permit the examination of a much larger volume of
water than that collected for the Sedgwick-Rafter analysis.
At those stations where net plankton hauls were made, Aphanizomenon
flos-aquae was the dominant organism as shown in Table VII. Although the
Sedgwick-Rafter analyses revealed low numbers of this organism, calcu-
lations based on the amounts of water filtered, the amount of plankton
concentrate obtained, and the number of organisms in that concentrate
indicate that the densities obtained from both Sedgwick-Rafter and net
plankton analyses are comparable. Aphanizomenon flos-aquae was easily
seen in the lakes even though present in low numbers because of its habit
of forming large aggregates. Similarly, copepods and cladocerans could
easily be seen in the lakes though only a few organisms were present. The
presence of the blue-green algae Aphanizomenon flos-aquae and Anabaena
which are both capable of fixing atmospheric nitrogen (converting molecular
nitrogen to ammonia) supports the hypothesis discussed earlier that the
phytoplankton are nitrogen limited. In many bodies of water, these forms
become abundant during the late summer and early fall months particularly
-------
Genera Species
Rotifers
Asplanchia sp.
Kellicottia sp.
Synchaeta sp .
Cladocerans
Bosmina sp .
Daphnia spp.
Copepods
Cyclops sp .
Diaptomus spp.
Water Mite
Blue Greens
Aphanizomenan flos -aquae
Oscillatoria sp .
Anabaena sp .
Greens
Volvox sp .
Scenedesmus sp .
Dictyosphaerium sp .
Oedogonium sp .
Pandorina sp.
Pediastrum sp .
Carteria sp.
Closterium sp.
Unknown coccoid form
Other
Dinobryan sp.
TABLE VII
Grand Lake
L-3
Oblique
Hand Tow
3
1
48
121
11
18
14,586
3
101
2
85
Net Plankton
Sample Analyses
Shadow Mountain Lake
L-4
Oblique
Hand Tow
19
3
88
6
8
19,320
5
22
70
1
210
L-6
Vert. Haul
From 20' Deep
26
1
6
3
88
28
6
1
9,905
35
8
35
17
70
L-8
Surface
Tow
10
55
322
13
78
74,690
70
95
70
70
280
350
Lake Granby
L-12 L-13
Vert. Haul Vert. Haul
From 25 ' Deep From 17 ' Deep
56 59
1
106 72
104 31
13 . 20
127 47
201,460 167,160
8
-------
TABLE VII (Continued) Net Plankton Sample Analyses
Genera Species
Grand Lake
L-3
Oblique
Hand Tow
Shadow Mountain Lake
Lake Granby
L-4
Ob 1ique
Hand Tow
L-6
Vert. Haul
From 20' Deep
L-8
Surface
Tow
L-12
Vert. Haul
From 25' Deep
L-13
Vert. Haul
From 17' Deep
Diatoms
Navicula sp.
Fragilaria sp.
Asterionella sp.
Cymbella sp.
Cyclotella sp.
Melosira spp.
Fragilaria Crotonensis
Cyclotella Bodanica
Nitzschia sp.
Tabellaria sp.
Stephanodiscus sp.
70
1,610
210
3,780
3,990
70
560
210
70
70
105
35
105
490
9,380
910
350
8,120
Totals
15,065
30,252
11,087
94,863
201,867
167,397
-------
38
if high phosphorus to nitrogen ratios prevail. Therefore, reduction of
the phosphorus concentration in the lake is necessary to prevent "blooms"
by the nitrogen-fixing blue-green algae. Since the natural removal of
phosphorus by outflows and combination with consolidated bottom sediments
is a slow process, a reduction in the phosphorus inflows to the lakes is
the logical control measure.
While bottom vegetation was not sampled in any of the lakes, it was
observed in relative abundance in Shadow Mountain Lake. The bottom
growth was particularly thick along the west shoreline of Shadow Mountain
Lake. This same area was reported to have light to moderate growth during
the October 2, 1967, survey.
EFFECTS OF NATURAL INFLOWS UPON THE WATER QUALITY IN THE LAKES
The chemical and physical data for all tributary stations are contained
in Table VIII. The natural runoff into the lakes (Station 1-1 through 1-11)
had a flow-weighted average inorganic nitrogen concentration of 0.07 mgN/1,
orthophosphate concentration of 0.007 mgP/1, and total soluble phosphorus
concentration of 0.064 mgP/1. Comparing this with the criteria established
earlier, it is apparent that the total soluble phosphorus concentrations in
the natural inflows is greater than the upper limit of 0.05 mgP/1 suggested
for low flow conditions while the orthophosphate concentration is less
than the suggested limit of 0.010 mgP/1. At the time of this survey, the
tributary inflow approached low flow conditions which is generally associ-
ated with higher mineral concentrations. Therefore, the average annual
natural orthophosphate and total soluble phosphorus inputs from the natural
inflows are believed to be less than 0.010 mgP/1 and 0.050 mgP/1 respec-
tively, but a short-term water quality surveillance program to collect
-------
39
TABLE VIII Flow and Nutrient Concentrations Measured
Station
Number
1-1
1-2
1-3
1-4
1-5
1-6
1-7
1-9
1-10
1-11
Flow Weighted
Date &
Time
Sampled
Aug. 28
0840
Aug. 28
0905
Aug. 28
1015
Aug. 28
1000
Aug. 28
1600
Aug. 28
1615
Aug. 28
1640
Aug. 28
1335
Aug. 28
1250
Aug. 28
1235
Average 1-1 through 1-11
i
at Tributary Stations
Nitrogen
Gage Inor-
Ht/Flow N03- NH3- ganic
Cfs.I/ mgN/1 mgN/1 mgN/1
4.00 .05 .02 .07
38.80
4.17 .05 .02 .07
4.50
0.97 .05 .01 .06
1.70
3.25 .05 .02 .07
1.80
0.78 .05 .01 .06
17.00
7.69 .05 .02 .07
26.70
0.45 .05 .04 .09
2.20
3.49 .05 .01 .06
28.00
4.60 .05 .03 .08
0.10
0.62 .05 .02 .07
3.60
.05 .02 .07
Phosphates
Ortho Total-Sol
mgP/1 meP/1
.003 .062
.003 .059
.003 .082
.003 .039
.003 .062
.003 .065
.023 .072
.006 .055
.110 .166
.091 .144
.007 .064
I/ To convert to M /Sec. multiply by .02832.
-------
40
flow and quality data during all flow cycles should be conducted to
affirm this assumption.
EFFECT OF WASTEWATER DISCHARGES UPON NUTRIENT LEVELS IN THE LAKES
Two sources of treated wastewater enter the lakes studied. The major
sources are the Grand Lake and the Shadow Mountain Government Camp waste-
water treatment facilities which serve approximately 4,000 people during
the summer months and about 450 people the remainder of the year. The
residences and businesses which use septic tank and subsurface disposal
fields for wastewater treatment and disposal constitute the other sources.
According to personnel of the Colorado State Health Department (5), there
are approximately 300 residences and businesses served by individual
systems. On a typical summer weekend, these individual systems probably
receive the wastes of 1,500 or more people.
The quality of the effluent from the Grand Lake wastewater treatment
facility is believed to be similar to the quality of the effluents from
the Shadow Mountain Government Camp system and the individual systems
and representative of the nutrient inflows from wastewater. Therefore,
the effects of wastewater on the lakes were evaluated by sampling the
Grand Lake wastewater treatment facility effluent. The results of the
chemical analyses in Table IX show that the concentrations of ammonia,
orthophosphates and total soluble phosphates averaged 13.38 mgN/1, 5.21
mgP/1 and 6.14 mgP/1 respectively, and are two to three orders of magni-
tude greater than the concentrations determined in natural runoff.
A more realistic view of the impact of domestic wastewater nutrients
on the lakes can be presented by conversion of the nutrient concentrations
from mg/1 to Ibs/day as shown in Table X. Analysis of this data shows
-------
41
TABLE IX Flow and Nutrient Concentrations
Measured in the Grand Lake Wastewater Treatment Facility Outfall, Station 1-16
Date
and
Time
Aug. 28
1030
Aug. 29
1310
Aug. 30
1515
Aug. 31
1630
Sept. 1
1325
Sept. 2
1625
FloY
gptn— '
30
202
150
202
202
175
N I
Nitrate
maN/1
.05
.05
.05
.05
.05
.09
T R 0 G
Ammonia
mgN/1
9.7
11.0
13.0
16.0
18.0
8.7
E N
Inorganic
mgN/1
9.75
11.05
13.05
16.05
18.05
8.79
PROS
Ortho
mgP/1
6.20
4.57
4.57
5.55
5.55
5.55
PRATES
Total Soluble
meP/1
7.18
5.87
5.55
6.85
6.20
5.87
Flow Weighted
AVERAGE 160 .06 13.38 13.43 5.21 6.14
I/ To convert to M /Sec. multiply by .63x10
-4
-------
42
TABLE X Measured Nutrient Input (Lbs/Day) to the Lakes
From Natural and Wastewater
Sta.Flow
No. AcFt/Day-'
1-1
1-2
1-3
1-4
1-5
1-6
1-7
1-9
1-10
1-11
77.0
8.9
3.4
3.6
33.7
53.0
4.4
55.5
0.2
7.1
N
Nitrate „.
IbsN/Day-
10.5
1.2
0.5
0.5
4.6
7.2
0.6
7.5
0.3
1.0
I T R 0 G E N
Flows
P H 0 S
Ammonia Inorganic. Ortho
IbsN/Day-' IbsN/Day-' IbsP/Day-2-'
4'. 2
0.5
0.1
0.2
0.9
2.9
0.5
1.5
0.2
0.4
14.7
1.7
0.6
0.7
5.5
10.1
1.1
9.0
0.5
1.4
0.69
0.08
0.03
0.03
.0.30
0.48
0.28
0.98
0.06
1.76
P H A T E S
Total Soluble
IbsP/dayl'
12.99
1.43
0.76
0.38
5.68
9.37
0.86
8.30
0.09
2.78
33.9
11.4
45.3
4.69
42.64
1-16- 0.7
WASTEWATER FLOWS
0.1 25.5 25.6
9.92
11.69
I/ To convert to M /Sec. multiply by .01428.
2/ To convert to Kg/Day multiply by .4536.
3_/ Flow-Weighted Average.
-------
43
that the Grand Lake wastewater treatment facility effluent, while contribu-
ting only 0.28 percent of the total inflow, contributed 36 percent of the
inorganic nitrogen, 68 percent of the orthophosphates, and 21.5 percent of
the total soluble phosphates as compared to the natural runoff contributions
of 97.72 percent of the flow, 64 percent of the inorganic nitrogen, 32 per-
cent of the orthophosphates, and 78.5 percent of the total soluble phosphates.
Phosphorus is the element most often limiting to aquatic plant growth.
However, when present in abundance in conjunction with other environmental
conditions, phosphorus can stimulate algae growths that produce nuisance
tastes and odors, fish kills and otherwise impair water uses. Unlike
nitrogen, phosphorus cannot be fixed from the atmosphere by plants and is
added to the lakes by natural runoff or wastewater discharges (7). For
biological growth, the orthophosphate ion is the most readily available
source of phosphorus (8). As shown above, the Grand Lake wastewater treat-
ment facility contributed 68 percent of the orthophosphates entering the
lakes during the time of this survey. Considering this and the additional
quantity and quality of wastewater entering the lakes from other sources,
the evidence is that wastewater, the major contributor of orthophosphates,
is the cause of nutrient pollution of these lakes.
The natural runoff provided 99.7 percent of the inflow with an ortho-
phosphate concentration of 0.007 mgP/1. Therefore, to restrict the flow-
weighted average orthophosphate concentration entering the lake to 0.010
mgP/1, the suggested maximum, the orthophosphate concentration in waste-
waters discharged to the lake cannot exceed 1.054 mgP/1. Since the measured
orthophosphate concentration in the Grand Lake wastewater treatment facility
-------
44
effluent was 5.21 mgP/1, an additional 80 percent reduction in orthophos-
phate is required. This can only be accomplished by advanced waste
treatment methods.
Beyond nutrient inputs, it has been shown that organic matter is also
an important factor affecting the growth of algae, although the specific
amount of organic matter necessary to sustain growth has not been quanti-
fied (8). Hinman (2) presents data showing that the Grand Lake wastewater
treatment facility only achieved a 45 percent suspended solids reduction
during August 1969, and the sludge accumulations noticed during the
October 2, 1967, survey were also observed by Federal Water Pollution Con-
trol Administration personnel during this survey. Therefore, the organic
matter necessary for algae growth is probably present in the lakes and is
contributed primarily by wastewater inflows.
In addition to phosphorus removal, an increase in the removal of
organic matter from wastewaters is also necessary to prevent water quality
degradation. However, the contribution of organic matter by natural run-
off is unknown and must be evaluated as part of water pollution control
programs for the lakes.
No information is available regarding the quality of spring runoff,
the effects of ice cover on water quality, etc. Development of a compre-
hensive plan for water quality control in the three lakes area will require
that these factors be evaluated.
-------
45
BIBLIOGRAPHY
1. American Public Health Association, American Water Works Association
and Water Pollution Control Federation, 1967, "Standard Methods for
the Examination of Water and Wastewater," 12th Edition, American
Public Health Association, 76a p.
2. Hinman, H. Fred, 1969, "Sanitary Survey Report, Grand Lake, Shadow
Mountain Reservoir, Lake Granby," Colorado Department of Health,
Water Pollution Control Division, 7 p plus appendix. (Mimeo)
3. Hutchinson, G. Evelyn, 1957, "A Treatise on Limnology," Vol. 1, John
Wiley and Sons, New York, 1015 p.
4. Lackey, J. B., 1949, "Plankton as Related to Nuisance Conditions in
Surface Water," "Limnological Aspects of Water Supply and Waste
Disposal," American Association for the Advancement of Science, pp 56-63,
5. Lee, Willis T., 1917, "The Geologic Story of the Rocky Mountain
National Park, Colorado," USDI, National Park Service, 89 p.
6. Mackenthun, Kenneth M. and Ingram, William M., 1967, "Biological
Associated Problems in Freshwater Environments, Their Identification,
Investigation and Control," USDI, FWPCA, 287 p.
7. Mackenthun, Kenneth M., 1968, "The Phosphorus Problem," Journal of
the American Water Works Association, Vol. 60, No. 9, pp 1047-54.
8. Nesbitt, John B., 1966, "Removal of Phosphorus from Municipal Sewage
Plant Effleunts," Engineer Research Bulletin B-93, The Pennsylvania
State University, College Park, Maryland, 54 p.
9. Palmer, C. M., 1959, "Algae in Water Supplies," U. S. Public Health
Service, Publication #657, 88p.
10. Sawyer, Glair N, and McCarty, Perry L., 1967, "Chemistry for Sanitary
Engineers," McGraw-Hill Book Company, New York 518 p.
11. U. S. Department of the Interior, Bureau of Reclamation, 1962, "The
Story of the Colorado-Big Thompson Project," Bureau of Reclamation,
56 p.
-------
46
APPENDIX A
PHYSICAL AND CHEMICAL DATA
FOR LAKE STATIONS
-------
Table A-l Physical-Chemical Data for Lake Stations
Date & Sample Tempera-
Station Time Depth ture
Number Sampled Feet °C
L-l
L-2
L-3
L-4
8/28/69
1015&1000
8/30/69
1120
9/1/69
0945
9/3/69
1005
8/28/69
1045
8/30/69
1135
9/1/69
1005
9/3/69
1025
8/28/69
1115
8/30/69
1110
9/1/69
1015
9/3/69
0955
8/28-0930
8/29-1250
8/30-1150
8/31-1535
9/1-1135
9/3-0945
0.0
60.0
0.0
120.0
0.0
120.0
0.0
135
0.0
130.0
0.0
70.0
0.0
80.0
0.0
70.0
0.0
30.0
0.0
40.0
0.0
40.0
0.0
40.0
2.5
2.5
5.0
5.0
5.0
4.0
16.0
17.0
15.5
8.5
14.5
9.0
15.5
11.5
17.0
9.0
15.0
8.5
15.5
7.5
15.5
13.0
17.0
17.0
15.0
12.0
15.0
10.5
15.5
10.5
13.0
14.5
14.0
15.0
14.0
15.0
PH
7.4
7.6
7.5
7.3
7.6
7.6
7.4
6.9
7.6
6.8
7.3
7.1
7.6
7.3
7.5
7.3
...
7.1
8.3
7.4
7.3
6.9
7.0
7.2
7.2
7.8
7.2
8.5
7.5
7.4
Specific
Cond. D. 0.
pmhos mg/1
..
--
50
^50
<50
00
<50
<50
__
--
-------
Table A-l(Continued) Physical-Chemical Data for Lake Stations
Date & Sample
Station Time Depth
Number Sampled Feet
L-5
L-6
L-7
L-8
L-9
L-10
L-ll
8/29/69
1300
9/1-1115
9/3-0930
8/29/69
1240
9/2
1345
8/29-1225
9/2/69
1330
8/29-1340
8/30-1500
8/29/69
1130
9/2/69
1135
. 8/29/69
1110
9/2/69
1115
8/29/69
1100 ;
9/2/69
1100
0.0
20.0
6-12
5-10
0.0
20.0
0.0
20.0
7.5-15
0.0
20.0
2.5-5
2.5-5
0.0
36.0
0.0
34.0
0.0
50.0
0.0
66.0
0.0
76.0
0.0
110.0
Tempera-
ture
°C PH
14.0
14.0
13.0
13.5
15.0
13.0
15.0
12.0
15.0
16.0
12.0
17.0
17.5
19.0
14.0
18.5
14.5
18.0
11.0
18.0
11.0
18.0
10.0
18.0
11.0
7.5
7.1
6.8
7.1
7.5
7.4
7.3
7.1
7.5
7.7
7.0
7.7
8.0
7.5
7.3
7.6
7.0
7.9
7.1
7.3
7.0
7.1
6.5
7.7
7.2
Specific
Cond. D. 0.
^mhos mg/ 1
63
62
60
^50
63
60
60
63
52
60
63
70
^-50
55
50
55
60
55
55
60
55
55
60
60
55
7.8
6.0
5.6
5.2
7.8
6.3
7.2
5.8
8.0
6.8
5.6
8.3
7.5
7.6
6.4
6.6
4.8
7.8
5.1
6.6
4.1
7.5
5.2
7.5
4.1
N03-
mg/1
as N
± .05
2.05
£ .05
£.05
£..05
* .05
f .05
£.05
i.05
*.05
Z.Q5
±.Q5
£.05
•^.05
i.05
-i.,05
i.05
£..05
.11
±.05
.13
i.05
.14
i.05
i.05
NIT
NH3
mg/1
as N
.03
.19
.05
.02
.02
.05
.02
.03
.03
.02
.02
.57
.06
* .01
.10
.01
.03
<. .01
^ .01
.02
.02
.01
.03
.01
.24
R 0 G E N
Organic
•mg/1
as N
.43
.29
.35
.13
.20
.32
.23
.14
.24
.15
.17
.39
.38
.10
.14
.11
.18
.15
.15
.18
.23
.15
.17
.13
.28
Total
Kjeldahl
mg/1 as N
.46
.48
.40
.15
.22
.37
.25
.17
.27
.17
.19
.96
.44
.11
.24
.12
.21
.16
.16
.20
.25
.16
.20
.14
.52
PHOSPHATES
Ortho
mg/1
PO&
.02
.02
.02
.03
.02
.03
.02
.11
.39
.03
.09
.48
.19
.02
.10
.02
.04
.01
.08
.02
.14
.01
.05
.02
.27
Total Soluble
mg/1 mg/1
PO/, P
.06
.10
.05
.06
.04
.06
.03
.17
.43
.06
.10
.78
.25
.22
.31
.08
.08
.26
.27
.04
.14
.15
.33
.04
.28
.020
.033
.016
.020
.013
.020
.010
.055
.140
.020
.033
.254
.082
.072
.101
.026
.026
.085
.088
.013
.046
.099
.108
.013
.091
-------
Table A-1(Continued) Physical-Chemical Data for Lake Stations
NITROGEN
Date &
Station Time
Number Sampled
L-12
L-13
L-14
8/29/69
0930
8/29/69
1025
8/29-1010
9/2-1020
Sample
Depth
Feet
0.0
40.0
0.0
34.0
7.5-15
5-10
Tempera-
ture
°C PH
18.0
12.0
19.0
13.0
18.0
17.0
8.5
6.8
6.9
6.3
7.6
7.1
Specific
Cond. D. 0.
umhos mg/1
55
60
55
55
55
52
7.2
4.4
7.6
5.0
7.1
6.1
N03-
mg/1
as N
±.05
.08
-------
50
APPENDIX B
WATER QUALITY STANDARDS FOR COLORADO
-------
51
COLORADO DEPARTMENT OF HEALTH
Water Pollution Control Commission
^210 East 11th Avenue
Denver, Colorado 80220
Adopted May 15, 1968
WATER QUALITY STANDARDS FOR COLORADO
The Second Session of the Forty-Fifth General Assembly of the State
of Colorado passed Water Pollution Control Legislation for the State of Colorado
as set out in Chapter 4*4, Session Laws 1966. In adopting this legislation,
the following legislative declaration was made:
"Whereas the pollution of the waters of this state constitutes
a menace to public health and welfare, creates public nuisances,
is harmful to wildlife, fish and other aquatic life,and impairs
domestic, agricultural, industrial,recreational, and other
beneficial uses of water; and whereas the problem of water
pollution of this state is closely related to the problem of
water pollution in adjoining states; and whereas it is the public
policy of this state to conserve the waters of the state and to
protect, maintain, and improve the quality thereof for public
water supplies, for the propagation of wildlife, fish and other
aquatic life, and for domestic, agricultural, industrial,
recreational, and other beneficial uses, and to provide that
no wastes be discharged into any waters of the state without
first being given the degree of treatment necessary to protect
the beneficial uses of such water, it is hereby declared that
the prevention, abatement, and control of the pollution of
the waters of this state are affected with a public interest,
and the provisions of this act are enacted in the exercise of the
police powers of this state for the purpose of protecting the
health, peace, and safety, and general welfare of the people
of this state."
These standards are the foundation for the classification of the
waters of the State of Colorado.
Standards are subject to revision as technical data, surveillance
programs, and technological advances make such revisions desirable.
For purposes of enforcement of these standards, sampling will be
done at a point where these standards can be evaluated.
For purposes of enforcement of water classification standards,
sampling of the waters will be done at any point, except for areas immediately
adjacent to outfalls and except as may be noted in the text of the standards.
In such areas, cognizance will be given to the opportunity for admixture of
waste effluents with receiving water.
-------
52
Water Quality Standards For Colorado
Adopted May 15, J_9j>8
Tests or analytical procedures to determine compliance with standards
will, insofar as practicable and applicable, be made in accordance with the
methods given in the latest edition of "Standard Methods For The Examination
Of Water And Waste Water" published by the American Public Health Association,
or in accordance with tests or analytical procedures that have been found to be
equal or more applicable and satisfactory and accepted and approved by the
Commission.
In areas where a body of water is classified for more than one use,
the standards applicable to each use shall apply and in case of a conflict,
the more restrictive standards shall prevail in each instance.
Where and when additional waters become available, hearings will be
held on the possible classification or reclassification of such waters for
further enhancement. The quality of water will be maintained as high as possible
and in no case shall stream standards be violated.
It is expected that the present uses of the waters of Colorado will
continue but if other uses develop, streams may be classified or reclassified
after public hearings.
I. BASIC STANDARDS APPLICABLE TO ALL WATERS:
A. All wastes capable of treatment or control prior to discharge into any
waters of the state, shall receive secondary treatment with disinfection
or its industrial waste equivalent, as determined by the State Water
Pollution Control Commission. Lesser degrees of treatment or control
may be permitted only where it can be demonstrated that the standards
applicable to the classified use of the water can be attained.
Greater degrees of treatment or control will be required where it
can be demonstrated that it is necessary to comply with the standards
applicable to the classified use of the water.
B. Free from substances attributable to municipal, domestic, or industrial
wastes, or other controllable sources that will either settle to form
unsightly, putrescent, or odorous bottom deposits, or will interfere
with the,classified use of the water.
C. Free from unsighly floating debris, oil, grease, scum, and other
floating material attributable to municipal, domestic, or industrial
wastes, or other controllable sources.
D. Free from materials attributable to municipal, domestic, or industrial
wastes, or other controllable sources that will produce odor in the
water or produce an appreciable change in the existing color, taste,
turbidity or other conditions that interfere with the classified use
of the water.
E. Free from high temperatures, biocides, toxic, or other deleterious
substances attributable to municipal, domestic, or industrial wastes,
or other controllable sources in levels, concentrations, or combinations
sufficient to be harmful to human or animal life.
-------
Water Quality Standards For Colorado
Adopted May 15, 1968 ___
Radioactive materials attributable to municipal, industrial or other
controllable sources will be minimum concentrations that are physically
and economically feasible to achieve. In no case shall such materials
in the stream exceed the limits established in the current edition of
the U.S. Public Health Service Drinking Water Standards or the limits
approved by the Federal Radiation Council, or, in the absence of 'any
limits specified by the U.S. Public Healtn Serv.ice or the Federal
Radiation Council, 1/30 of the 168-hour-week values for other radio-
active substances specified in the National Bureau of Standards
Handbook 69.
II. ADDITIONAL WATER QUALITY STANDARDS KOR BODIES OF WATER THAT HAVE BEEN
CLASSIFIED FOR ANY OF THE FOLLOWING USES:
CLASS A.
The following standards shai1 apply to water withdrawn for treatment as a
potable supply:
1. Bacter i a: The annual average number of coliform bacteria at any
sampling station shall not exceed the historical average by more
than 20% and in no case shall the monthly average of the number
of coliform bacteria exceed 5,000 per 100 milliliter (either MPN or
MF count). AM averages shall be computed logarithmically.
2. Dissolved Oxygen: Dissolved oxygen shall not be less than k milligrams
per 1i ter.
3. pH: The pH shall be maintained between 6.0 and 9-0.
k. Taste and Odor: Free from materials attributable to municipal, domestic,
or industrial wastes, or other controllable sources that will produce
taste or odor in the water.
5. Pi ssolved Sol ids: Total dissolved solids, annual volume weighted average,
should be less than 500 milligrams per liter.
6. Selected Chemical Constituents: The following substances shall not be
present in such amounts as to exceed the specified concentrations in a
potable water supply according to the mandatory requirements of the
latest edition of the U.S. Public Health Service Drrnking Water Standards:
Substance Concentration - mg/1
Arsenic ----------------0.05
Barium -----------.-----).QO
Cadmium -----------------0.01
Chromium (Hexavalent) --------- 0.05
Cyanide ----------------0.20
Lead ------------- 0.05
Selenium --- _______ o.Ol
Silver ----- Q.05
-------
54
Water Quality Standards For Colorado
Adopted Hay 15, 1968
CLASS B.
1. The following standards shall apply to waters classified for fish and
wildlife (Cold Water Fishery):
a. Dissolved Oxygen: In cold water fisheries, the dissolved oxygen
content shall in no case go below 6 milligrams per liter.
b. pH: pH shall be maintained between 6.5 and 8,5- No controllable
pH change will be permitted which will interfere with fish and
aquat i c 1i fe.
c. Turbid i ty: No turbidity shall exist in concentrations that will
impair natural and developed fisheries.
d. Temperature: In cold water fisheries the temperatures shall not
exceed 70 F. No controllable temperature change will be permitted
which will interfere with, the spawning and other aspects of fish life.
e. Toxic Material: Free from biocides, toxic, or other deleterious
substances attributable to municipal, domestic, or industrial
wastes, or other controllable sources in levels, concentrations,
or combinations sufficient to be harmful to aquatic life.
f. Other Material: Free from materials attributable to municipal,
domestic, or industrial wastes, or other controllable sources
that will produce off-flavor in the flesh of fish.
2. The following standards shall apply to waters classified for fish and
wildlife (Warm Water Fishery):
a. Dissolved Oxygen: In warm water fisheries, dissolved oxygen content
shall in no case go below 5 milligrams per liter.
b. pH: pH shall be maintained between 6.5 and 8.5. No controllable
pH change will be permitted which will interfere with fish and
aquati c 1i fe.
c. Turb i di ty: No turbidity shall exist in concentrations that will
impair natural and developed fisheries.
d. Temperature: In warm water fisheries the temperatures shall not
exceed 90 F. No controllable temperature change will be permitted
which will interfere with spawning and other aspects of fish life.
e. Toxi c Materi al: Free from biocides, toxic, or other deleterious
substances attributable to municipal, domestic, or industrial
wastes, or other controllable sources in levels, concentrations,
or combinations sufficient to be harmful to aquatic life.
f. Other Materi al: Free from materials attributable to municipal,
domestic, or industrial wastes, or other controllable sources
that will produce off-flavor in the flesh of fish.
-------
Water Quality Standards For Colorado
Adopted May 15, 1968'
CLASS B - continued
3. The following standards shall apply to recreational waters classified
for body contact sports such as, but not limited to, swimming and
water ski i ng:
a. Bacteria: Total coliform bacteria shall not exceed 1,000 per
100 milliliters as a monthly average (either MPN or MF count);
nor exceed this number in more than 20% of the samples examined
during any month; nor exceed 2,^00 per 100 mill!liters in a
single sample. In addition, the fecal coliform count shall not
exceed 100 per 100 mill!liters and the fecal streptococcus count
shall not exceed 20 per 100 milliliters, both of these limits to
be an average of five (5) consecutive samples within a month.
b. pH: pH shall be maintained between 6.5 and 8.5.
CLASS C:
The following standards shall apply to waters classified for industrial uses:
1. Dissolved Oxygen: Dissolved oxygen content shall not go below
3 mi 111 grams per liter.
2. pH: pH shall be maintained between 5-0 and 9.0.
3. Turbidity: No turbidity shall exist in concentrations that will
interfere with established levels of treatment.
*». Temperature: The temperature shall not exceed 93° F.
CLASS D:
1. The following standards shall apply to waters classified for irrigation:
a. Total Dissolved Solids (Salt)Concentration:
A time-weighted monthly mean at a monitoring station which exceeds
the time-weighted monthly mean for a base period established
by the Commission by more than two standard deviations shall be
subject to review by the Commission.
b. Sodium Adsorption Ratio:
A time-weighted monthly mean at a monitoring station which exceeds
the time-weighted monthly mean for a base period established by
the Commission by more than two standard deviations shall be subject
to review by the Commission.
-------
Water Quality Standards For Colorado
Adopted May 15, 1968
56
CLASS D - continued
c. Toxi c Material:
Free from biocides, toxic, or other deleterious substances
attributable to municpal, domestic, industrial wastes, or other
controllable sources in concentrations or combinations which
are harmful to crop life.
2. The following standards shall apply to waters classified for livestock
water!ng:
a. Soluble Salts: The soluble salts shall not exceed 3,000 milligrams
per 1i ter.
Betty M. .Chronic, Secretary
Colorado Water Pollution Control Commission
Richard T. Eckles, Chairman
Colorado Water Pollution Control Commission
-------
57
APPENDIX C
GLOSSARY
-------
sa
GLOSSARY
ALGAE BLOOM - A concentration of phytoplankton exceeding 500 organisms/ml.
BENTHIC REGION - The bottom of lakes and streams; the substratum that
supports the bottom dwelling plants and animals.
CLINOGRADE - A distribution of dissolved oxygen in the hypolimnion which
decreases with depth - approaching zero near the lake bottom.
EPILIMNION - That upper layer of a body of water in which the water
temperature is virtually uniform.
EUPHOTIC ZONE - The surface layers of a lake in which light provides the
energy for organic production from mineral substances.
EUTROPHIC WATERS - Waters with a good supply of nutrients; they may support
rich organic production, such as algal blooms.
EUTROPHICATION - The intentional or unintentional enrichment of water.
HYDROLYSIS - A chemical reaction in which a compound reacts with the ions
of water to fonfl a weak acid, a weak base, or both.
HYPOLIMNION - The region of a body of water which extends from the thermo-
cline to the bottom of the lake and has a nearly uniform temperature.
MESOTROPHIC - Waters with a moderate supply of nutrients; they will support
organic production and will occasionally support algal blooms.
OLIGOTROPHIC WATERS - Waters with a small supply of nutrients; hence, they
support little organic production.
ORTHOGRADE - A nearly uniform distribution of oxygen in the hypolimnion of
a lake.
PHOTOSYNTHESIS - The process by which living plant cells, in the presence
of light, convert organic and inorganic matter to cell material.
PHYTOPLANKTON - Plant microorganisms, such as certain algae, living
unattached in the water.
PLANKTON - Organisms of relatively small size, mostly microscopic, that
either have relatively small powers of locomotion or drift in the
water subject to the action of waves and currents.
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SECCHI DISC - A circular metal plate, 20 cm in diameter, the upper
surface of which is divided into four equal quadrants and so painted
that two quadrants directly opposite each other are black and the
intervening ones white.
THERMOCLINE - The layer in a body of water in which the drop in temperature
equals or exceeds one degree centrigrade for each meter or approximately
three feet of water depth.
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