WATER QUALITY STUDY:
MIDDLE SNAKE RIVER
FEDERAL WATER
POLLUTION CONTROL
ADMINISTRATION
NORTHWEST REGION
PORTLAND,OREGON
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WATER QUALITY STUDY:
MIDDLE SNAKE RIVER
Prepared by
Danforth G. Bodien
Working Paper No. 69
Technical Assistance & Investigations Branch
Office of Technical Programs
United States Department of the Interior
Federal Water Pollution Control Administration
Northwest Region
501 Pittock Block
Portland, Oregon
February, 1970
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CONTENTS
INTRODUCTION 1
Background. 1
Authority. * 2
Scope 2
Study Area 2
Study Time 2
Objectives 4
Acknowledgments. 4
SUMMARY 5
Findings 5
Conclusions. 6
STUDY AREA DESCRIPTION 9
WATER USES 11
WATER QUALITY CRITERIA 15
Standards 15
Other Criteria 15
SAMPLING AND ANALYTICAL PROGRAM 19
Survey Data Selection 19
Sampling Point Selection 19
Sampling Procedures and Analytical Methods 23
Monitoring Program 24
SAMPLING RESULTS AND DISCUSSION 25
Hydrology 25
Water Quality 28
Dissolved Oxygen 28
Temper atur e 43
Nutrients and Algal Productivity 48
Sulfates and Sulfides 51
Dissolved Nitrogen 53
DEFINITION OF TERMS 63
BIBLIOGRAPHY 65
APPENDIX 67
Dissolved Oxygen and Temperature Monitoring Data
Table 1 -- Below Brownlee Dam
Table 2 -- Below Oxbow Dam
Table 3 -- Below Hells Canyon Dam
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LIST OF FIGURES
Figure Page
1. Middle Snake River Study Area 3
2. Isotherms, Dissolved Oxygen and Dissolved
Oxygen Saturation Profiles for Station 1
(Brownlee Log Boom) 37
3. Dissolved Oxygen Profile for Oxbow Reservoir 38
4. Dissolved Oxygen Saturation Profiles for Oxbow
Reservoir 39
5. Dissolved Oxygen Profiles for Hells Canyon
Reservoir 40
6. Dissolved Oxygen Saturation Profiles for Hells
Canyon Reservoir 41
7. Isotherms for Oxbow Reservoir 46
8. Isotherms for Hells Canyon Reservoir 47
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LIST OF TABLES
Table Page
1. Idaho Power Projects Data 10
2. Estimated Distribution of Maximum Runs of Salmon
and Steelhead Trout to the Study Area 12
3. Standards of Quality for Snake River Waters 16
4. Location of Sampling Points 21
5. Average Monthly Discharges in cfs for Snake River
in Study Area 26
6. Spillage for Brownlee and Oxbow plus the Discharge
at the Hells Canyon gauge 27
7. Water Spilled in cfs, March, April, and May 1969
at Brownlee, Oxbow, and Hells Canyon Dams 29
8. Storet Data-Weiser 31
9. Storet Data-Brownlee 32
10. Storet Data-Oxbow 33
11. Storet Data-Hells Canyon 34
12. Storet Data-Asotin 35
13. Dissolved Oxygen Levels below Hells Canyon Dam.... 44
14. Chemical Parameter Profiles for Study Area 52
15. Analysis of Dissolved Gases 3/29/69 55
16. Analysis of Dissolved Gases 4/10/69 57
17. Analysis of Dissolved Gases 4/30/69 58
18. Analysis of Dissolved Gases 5/22/69 61
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INTRODUCTION
Background
The water quality of the Middle Snake River is of vital
concern to both State and Federal agencies. The reach from
Weiser, Idaho to the river's mouth has in the past several
years been the subject of several studies and investigations
relative to water quality and uses. The use of particular
interest is the anadromous fisheries of the Snake and its
major tributaries, such as the Salmon River.
A water quality study was initiated in July 1968 to
gather data in support of Department of the Interior testimony
presented before the Federal Power Commission license applica-
tion hearings on High Mountain Sheep Dam. Unusually heavy
rainfall during August 1968 required a supplemental field
survey in August 1969. This follow-up survey was further
justified by Secretary Hickel's request for a moratorium on
project construction in the Snake during which more studies
were to be undertaken.
This report includes the data from the above mentioned
surveys as well as data from the Federal Water Pollution Control
Administration (FWPCA) Pollution Surveillance Branch, Northwest
Regional Office, the U.S. Geological Survey, and the Bureau of
Commercial Fisheries.
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Authority
Section 5 of the Federal Water Pollution Control Act, as
amended, authorizes the Secretary of Interior to conduct
11. . .studies relating to the causes, control, and prevention
of water pollution."
Scope
Study Area
The study area, illustrated in Figure 1, included the reach
of the Snake River from Weiser, Idaho (River Mile 351.6) to the
mouth of the Clearwater River at Lewiston, Idaho (River Mile 139.3).
The main emphasis of the study, shown as the shaded area in
Figure 1, was concentrated in the reach from the Brownlee Reservoir
log boom (River Mile 285.2) to Wild Sheep Creek Rapids (River
Mile 241.4) below Hells Canyon Dam.
Study Time
The study consisted of two phases. The first phase involved
the installation of three continuous dissolved oxygen (D.O.) and
temperature recorders for a three-month period commencing in
July of 1968. The second phase involved four one-week surveys,
one each during the months of August, September, and October
1968 and August 1969.
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O 'O JO JO 40 SO
FIGURE 1 Middle Snake River Study Area
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Objectives
The objectives of the study were to define the existing
water quality conditions of the Middle Snake River and to
determine the overall effects of the three individual Idaho
Power Company projects (Brownlee, Oxbow, and Hells Canyon)
upon water quality.
Acknowledgments
The assistance and cooperation of the Idaho Power Company
is gratefully acknowledged.
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SUMMARY
Findings
1. A 34 to 38 percent reduction in dissolved oxygen concentra-
tions was measured between inflow and outflow in Brownlee
Reservoir compared with essentially no change in either Oxbow
or Hells Canyon Reservoirs.
2. Measured dissolved oxygen levels from Brownlee Dam to Wild
Sheep Creek Rapids below Hells Canyon Dam were below criteria of
applicable water quality standards except where algal activity
was high. During the summer months the major portion of water
in Oxbow and Hells Canyon Reservoirs had a D.O. concentration
ranging from 5 to 6 milligrams per liter (mg/1).
3. The increase in dissolved oxygen measured in the river below
Hells Canyon Dam was small, ranging from 0.9 to 1.4 mg/1 in a
six-mile reach.
4. Temperatures in each of the three reservoirs during the
summer months were uniform to a depth of approximately 150 feet.
A thermocline exists in Hells Canyon Reservoir below which the
dissolved oxygen measured was zero.
5. When looking at average annual temperatures, less than a
1 C. change was noted between inflow and outflow in any of the
three reservoirs.
6. Significant algal concentrations were noted in all three
reservoirs.
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7. A decrease in turbidity, total phosphorus, and total kjeldahl
nitrogen concentrations was measured between inflow and outflow
in Brownlee Reservoir with no apparent change between inflow and
outflow in Oxbow and Hells Canyon Reservoirs.
8. Essentially no change in either orthophosphate or ammonia
nitrogen concentrations was measured between inflow and outflow
of the three reservoirs.
9. Moderately high sulfate levels ranging from 12 to 60 mg/1
exist throughout the study area with conversion to hydrogen sulfide
gas in areas with zero dissolved oxygen.
10. Spillage at the three dams during the high spring flows of
1969 resulted in dissolved nitrogen concentrations as high as
135 percent.
Conclusions
1. The reduction in dissolved oxygen between inflow and outflow
in Brownlee Reservoir is due to a combination of organic solids
which settle out, creating an oxygen-consuming benthic load, and
the decomposition of dissolved and suspended organics.
2. Reaeration in the 6 miles below Hells Canyon Dam is limited
as the travel time is short and only a small percentage of the
flow is exposed at the surface.
3. The total phosphorus and total kjeldahl nitrogen removed
in Brownlee Reservoir were in solids which settled out.
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4. The discharge of waters from below the thermocline in
Brownlee and Hells Canyon Reservoirs is potentially toxic to
fish because these waters contain hydrogen sulfide and ammonia.
5. The amount of dissolved nitrogen added through spilling is
a function of the flow and the depth of plunge in the pool.
6. Water supersaturated with dissolved nitrogen returns to
equilibrium very slowly in impoundments.
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STUDY AREA DESCRIPTION
The area considered in this study is a 213-mile section
of the Snake River extending from Weiser to Lewiston, Idaho.
In this 213-mile reach, the Snake borders three states: Idaho
on the east, and Oregon and Washington on the west. Major
tributaries include the Burnt, Powder, Imnaha, Salmon, and
Grande Ronde Rivers. Ninety-three and one-half miles are
impounded behind three dams built and operated by the Idaho
Power Company. Data relating to these three projects can be
found in Table 1.
The physical characteristics of the study area are striking.
For the major portion of the 213-mile reach, the Snake River
flows through a steep-walled, rough-terrained, narrow canyon
which at its deepest point is over 5,500 feet deep.
Climate of the Middle Snake region is classified as semi-
arid. Rainfall averages 11 inches annually at Weiser and 13
inches at Lewiston, with less than one-quarter inch during
the summer months. Annual temperatures average 51 F. at Weiser
and 52 F. at Lewiston with over 70 days of at least 90 F. Pan
evaporation from the reservoirs averages 30 to 40 inches per year
with 80 percent of the total between May and October. Winds in
the canyon generally blow downstream during summer months and
upstream during winter months.
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10
TABLE 1
IDAHO POWER PROJECTS DATA
Type of Dam
Year Completed
Location of Dam (River mile)
Reservoir Length (miles)
Reservoir Surface Area (acres)
Total Storage (acre-ft.)
Height of Dam (ft.)
Elev., Top of Dam (ft.)
Water Surface Elev., max.
Water Surface Elev., mi n.
Elev., Tailwater (ft.)
£ Elev., Penstocks (ft.)
Brown lee
Rock fill
1959
284
57%
15 ,000
1,470,000
395
2090
2077
1976
1805
1948
Oxbow
Rock fill
1961
271
13
1,145
57,500
205
1825
1805
1800
1688
1750
Hells Canyon
Concrete gravity
1968
247.5
23
2,400
167,200
330
1695
1688
1683
1475
1550
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WATER USES
The present major uses of surface water of the Middle
Snake are power production, recreation, and fish and wildlife.
A small amount of irrigation is practiced along benches and
bottom land.
Snake River waters are used for a variety of recreational
purposes. Most of these activities are centered in the Lewiston
area, where two public bathing beaches are located. Pleasure
boating and water skiing are also popular in this area. Else-
where in the study area recreational uses are small due to
poor accessibility and remote location. The three reservoirs
studied are sparsely used with Brownlee receiving the greatest
use. However, these remote areas constitute important outdoor
recreational resources and legislation to set aside portions
of the Snake and/or tributaries as wild rivers has been proposed.
The Bureau of Commercial Fisheries has made estimates of
the maximum runs of salmon and steelhead in the Snake River
system. Table 2 lists the distribution of these fish in the
study area.
, Fish activity in the study area is heavy. The varieties of
species, listed in Table 2, are such that either up or downstream
migration is ongoing each month of the year. In addition, all
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12
TABLE 2
ESTIMATED DISTRIBUTION OF MAXIMUM RUNS OF SALMON
AND STEELHEAD TROUT TO THE STUDY AREA a/
Fall Spring-Summer Blueback
__. Snake River Run Chinook Chinook (Sockeye) Steel head
Asotin Creek 1,900
Grande Ronde River 12,200 18,200
Snake River
China Gardens-High Mtn. Sheep 3,600
Salmon River 95,300 3,500 39,700
Imnaha River 300 6,700 4,600
Snake River
High Mtn. Sheep-Appaloosa 1,100
Appaloosa-Pleasant Valley 3,600
Pleasant Valley-Hells Canyon 22,000
Hells Canyon Dam Fish Facilities 17,800 2,500 6,500
Small Tributaries
Imnaha River-Hells Canyon Dam 600 1,300
TOTAL 48,400 117,300 3,500 72,200
a/ This table is based on data available since counting began
at McNary Dam in 1954 and does not reflect the distribution
that could occur within any section or tributary in any
given year.
Data Source: U.S. Fish and Wildlife Service
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13
life stages of development are represented throughout the
year.
Many factors of water quality affect the lives of anadromous
fish, including high temperature, low dissolved oxygen, dissolved
nitrogen supersaturation, and disease.
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15
WATER QUALITY CRITERIA
Standards
In compliance with Section 10 of the Federal Water Pollution
Control Act, as amended, the States of Idaho, Oregon, and Washington
have established water quality standards for the Snake River. A
tabulation of the standards criteria for dissolved oxygen,
temperature, coliform bacteria, and hydrogen ion concentration
(pH) is presented in Table 3. The standards were established
to conform with the present and potential water uses of the
Snake River.
As part of each state's water quality standards, a statement
of non-degradation is required by the Secretary of Interior.
This policy provides for the maintenance of existing quality when
that quality is higher than levels set in the established standards.
Other Criteria
In addition to the standards presented in Table 3 other
parameters are important in maintaining water quality. Some of
the more important ones in the Middle Snake are nutrients
(nitrogen and phosphorus) and dissolved nitrogen gas.
Inorganic nitrogen and phosphorus are essential for the
growth of algae and aquatic plants. To avoid excessive growths
these nutrients should be limited in concentration to 0.30 mg/1
and 0.01 mg/1, respectively, according to Sawyer.(8)
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TABLE 3
STANDARDS OF QUALITY FOR SNAKE RIVER WATERS
(Established by the States of Oregon, Idaho and Washington)
Coliform Bacteria
(maximum allowable,
where associated with
fecal sources)
Hydrogen Ion
Concentrations (pH)
(allowable range)
Dissolved Oxygen (DO)
(minimum allowable
concentrations)
Temperatures
(maximum allowable)
Idaho
(river mile
to 247)
139
Idaho
(river mile 247
407.3)
Oregon
(river mile 172.0
to 407.3)
Washington
(river mile 0.0
to 172.0)
Average of 1000 organ-
isms/100 ml; 2400
organisms/100 ml in
20% of samples. Between
river miles 139 and 170,
average of 240 organisms/
100 ml.
Same as above.
7.0 to 9.0 (Induced
variation limited to
0.5 pH unit).
Same as above.
Average of 1000 organ-
isms/100 ml; 2400
organisms/100 ml in
20% of samples.
Median of 240 organ-
isms/100 ml; 1000 or-
ganisms/100 ml in 20%
of samples.
7.0 to 9.0
6.5 to 8.5 (Induced
variation limited to
0.25 units).
75% saturation at sea-
sonal low; 100% satu-
ration in spawning
areas during spawning,
hatching and fry stages
of salmonid fishes.
Same as above.
75% saturation at sea-
sonal low; 95% satura-
tion in spawning areas
during spawning, hatch-
ing and fry stages of
salmonid fishes.
8.0 mg/1
68°F (2°F in-
crease when river
temperatures are
66° or less).
70°F ('2°F increase
when river tempera-
tures are 68°F or
less).
70°F (2°F in-
crease when river
temperatures are
68°F or less).
68°F (when less
than 68°F the per-
missive increase,
"t", is limited by
the relationship
t=110/ (T-15), where
"T" represents the
resulting water tem-
perature).
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17
Dissolved nitrogen gas is becoming an important water
quality parameter in the Snake and main stem Columbia Rivers
as the cause of highly fatal gas-bubble disease in fish.
Concentrations of dissolved nitrogen as low as 104 percent
saturation have been reported to cause gas-bubble disease in
fish, - =
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SAMPLING AND: ANALYTICAL PROGRAM
. Survey Data Selection
During the formulation stage of the FWPCA study, two phases
of. field investigation were planned. These involved the installa-
tion of continuous monitors for dissolved oxygen (D.O.) and
temperature plus one-week surveys which were planned for the
months of August, September, and October 1968. August was
chosen as the month when the maximum effect of high temperature,
low flow, and high algal activity on water quality could be
observed. The September and October survey times were chosen
to measure the rate and degree of change in water quality
leading up to fall overturn in Brownlee and Hells Canyon
Reservoirs.
Because August of 1968 was unusually wet and cool, an
additional one week survey was undertaken in August of 1969.
Sampling Point Selection
Of iM.in concern in the study was the effect of the three
Idaho Power projects on water quality. Therefore, sampling
stations were established above and below the three dams. In
addition, samples were collected from the turbine penstocks. A
sampling station at Weiser was used as a control to assess
water quality entering Brownlee Reservoir. Besides these
stations, others were established at approximately five-mile
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20
intervals on both Oxbow and Hells Canyon Reservoir. At these
stations, as well as at the Brownlee log boom station, samples
were collected in mid-stream, at depths of 3 feet, 15 feet,
and each 30 feet thereafter. Below Hells Canyon Dam samples
were taken approximately every half mile so that any effect of
atmospheric reaeration on D.O. concentrations could be noted.
A tabulation of the points sampled with a description and
location in river miles can be found in Table 4.
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TABLE 4
LOCATION OF SAMPLING POINTS
STATION NO.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.-
12.
13,
14.
15.
16.
17.
18.
DESCRIPTION
Brownlee Dam log boom
Brownlee Dam penstock : . •:
Brownlee Dam tail race ,
Highway bridge below Brownlee
Dam
Oxbow Reservoir - Opposite
Idaho Powers Rest Station ^ mile
upstream of Jacobs Ladder Creek
Oxbow Reservoir at Sumner Creek
Oxbow Dam log boom
Oxbow Dam penstock
Oxbow Dam tail race
Highway bridge below Oxbow Dam
Hells Canyon Reservoir opposite
Homestead School
Hells Canyon Reservoir at Lime-
point Creek
Hells Canyon Reservoir at Leep
Creek
Hells Canyon Reservoir at Squaw
Creek
Hells Canyon Reservoir at Eagle
Bar - opposite substation
Hells Canyon Dam log boom.
Hells Canyon Dam penstock
Hells Canyon Dam tail race
RIVER MILE
285.2
285.0
284.8
284.0
280.0
277.0
273.7
273.5
271.0
269.7
265.8
261.7
256.9
252.7
249.4
248.2
248.0
247.8
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TABLE 4 (CONT.)
LOCATION OF SAMPLING POINTS
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
Snake River - 50 yards below
Hells Canyon Dam
Snake River at Deep Creek
Snake River at USGS Gaging
Station
Snake River at Hells Canyon
Creek
Snake River - Halfway between
Hells Canyon and Stud Creek
Snake River at Stud Creek
Snake River - Halfway between
Stud and Brush Creek
Snake River at Brush Creek
Snake River - % mile below
Brush Creek
Snake River - near Barton
Heights
Halfway between Brush and Battle
Creek
Snake River at lower Warm Springs
Snake River at Battle Creek
Snake River - halfway between
Battle and Wild Sheep Creek
Snake River at Wild Sheep Creek
247.7
247.4
247.6
246.8
246.3
245.9
245.3
244.7
244.5
244.1
243.5
242.9
242.2
241.8
241.4
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Sampling Procedures and Analytical Methods
Water samples were collected with either a Kemmerer or
Van Doren sampler.
When water depth was less than 50 feet, temperatures were
measured with a laboratory thermometer. Samples were taken from
the Kemmerer water sampler, placed in a plastic beaker, and the
temperature recorded. When depth was greater than 50 feet, a
fresh water bathythermograph (BT) was used in addition to the
hand temperature measurements.
Dissolved oxygen was measured in the field using the
Alsterberg (Azide) modification of the standard Winkler method.
Oxygen saturation levels were determined using saturation tables
from the twelfth edition of Standard Methods and were corrected
for elevation above sea level.
All additional samples were sent to the FWPCA Pacific Northwest
Water Laboratory (PNWL) in Corvallis, Oregon for analysis. Nutrient
samples were preserved with mercuric chloride (HgC^)* sulfate and
sulfide samples were preserved with zinc acetate [ZnCC-jHnOp)^],
and samples for biochemical oxygen damand (BOD) analysis were
iced before shipment to Corvallis. After arrival in Corvallis,
o
BOD samples were incubated for 5 days at 20 C.
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24
Turbidity samples were sent to the PNWL where they were
analysed using a Hach— turbidimeter.
Monitoring Program
Early in the study, continuous recording monitors for
dissolved oxygen and temperature were installed below each of
the three Idaho Power Projects. The units installed were
composed of an Electronics Instrument Laboratory Dissolved
Oxygen Probe and two Rustrak Recorders. These monitors were
installed at the end of July 1969 and were removed on October 16,
1969. During this period many problems developed which prevented
obtaining continuous data. However, the data obtained were
considered accurate since calibration checks were made every
two weeks or less.
Data obtained from the three monitors were reduced from
the charts and tabulated. These data can be found in the Appendix.
— Use of product and company names is for identification only
and does not constitute endorsement by the U.S. Department of the
Interior or the Federal Water Pollution Control Administration.
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SAMPLING RESULTS AND DISCUSSION
Hydrology
Flow data for the Snake River in the study area were obtained
from USGS records. Table 5 lists these data for three periods:
water year 1969 (October 1968-September 1969), water year 1968,
and a 15-year average for water years 1953-1967. The use of
the gauging station below Pine Creek was discontinued in 1968
because of the filling of Hells Canyon Reservoir. A station was
established below Hells Canyon Dam as a replacement. The flow at
this station should be very close to that measured below Pine
Creek since no major tributaries enter the Snake River between
these two locations. Major tributaries below Hells Canyon,
such as the Salmon, Imnaha, Grande Ronde, Asotin, and Clearwater,
greatly increase the flow at the Clarkston gauge.
As can be seen from Table 5, the average annual flows for
the reach from Weiser, Idaho to Hells Canyon Dam are approxi-
mately 18,000 cubic feet per second (cfs). High flows occur
during the months of March through June followed by low flows
during July and August.
Data from Table 5 show the marked increase in flow during
August 1968 which was 12 to 20 percent greater than the 15-year
average for this month. These high flows necessitated spilling
of water .at Brownlee and Oxbow Dams. Table 6 shows the amount
of spillage and the discharge at the Hells Canyon gauge.
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TABLE 5
AVERAGE MONTHLY DISCHARGE IN CFS FOR SNAKE RIVER IN STUDY AREA^/
Water Years 1953-1967
Station Oct. Nov. Dec. Jan. Feb. Mar. April May June July Aug. Sept. Ave.
Snake River 14,610 14,010 15,080 15,360 18,300 19,120 21,190 23,620 23,540 11,170 11,160 13,050 16,720
at Weiser
Snake River 15,140 14,520 16,490 18,470 21,330 21,170 23,180 24,090 24,440 11,290 11,040 13,440 17,840
below Pine CreekH/
Snake River 26,330 27,940 32,250 31,180 39,780 44,010 75,740 124,500 124,500 41,680 22,570 22,730 50,970
at Clarkston (adj.)
Water Year 1968
Snake River 14,900 15,800 15,400 15,100 18,800 14,200 11,100 11,300 13,100 9,380 12,950 12,300 13,600
at Weiser
Snake River - - 14.140 15,220 14,680
at Hells Canyon Dam
Snake River 26,100 30,800 31,100 33,200 55,400 44,060 44,610 74,650 93,170 31,140 25,170 26,500 42,840
at Clarkston
Water Year 1969
Snake River 14,200 15,900 16,200 24,100 25,600 29,700 39,000 28,700 19,000 10,800 10,500 13,300 20,500
at Weiser
Snake River 14,800 17,100 20,600 27,500 23,200 40,100 46,700 29,400 19,000 11,600 11,700 14,100 23,700
at Hells Canyon Dam
Snake River 31,300 39,100 37,000 55,300 48,300 62,600 117,000 143,000 86,900 33,700 20,500 21,400 58,000
at Clarkston
a/U.S.G.S. Data, subject to revision.
b/Snake River at Oxbow + incremental inflow from Pine Creek and ungaged area prior to January 1968.
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TABLE 6
SPILLAGE FOR BROWNLEE and OXBOW PLUS the DISCHARGE at the HELLS CANYON GAUGE a/
Date
August 1968
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28 .
29
30
31
September
1
2
3
4
5
a/ Idaho Power Data
Brown lee Spill
(cfs)
_
-
-
-
-
1,600
9,500
9,500
12,400
16,000
17,900
15,900
18,200
9,900
9,800
17,400
8,900
8,400
8,500
3,300
3,500
4,300
100
-
-
Oxbow Spill
(cfs 5
_
-
-
-
-
-
1,900
5,300
8,500
7,800
4,400
-
5,500
3,600
-
-
-
-
-
-
_
-
-
-
-
Hells Canyon
USGS Gauge
Discharge (cfs)
10,900
10,200
14,100
14,100
16,400
13,300
12,600
18,500
22,000
23,600
23,200
22,400
21,000
17,500
15,800
18,400
15,700
15,100
14,700
14,400
12,600
10,400
13,200
9,700
10,000
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28
Assuming plug flow in Oxbow and Hells Canyon Reservoirs,
and using a flow of 10,000 cfs for the summer months, the
detention times for Oxbow and Hells Canyon Reservoirs are about
3 days and 8 day,s, respectively.
Another item of interest in Table 5 is the large spring
flows for 1969. These flows, which were 90 to 100 percent
greater than the 15-year average flow, were accompanied by
spilling at all three dams. Table 7 lists the actual spillage
rates for the months of March through May 1969. Associated with
this great amount of spilling was a dissolved nitrogen problem
which will be discussed in detail in a later section.
Water Quality
Dissolved Oxygen
Of the parameters measured in the Middle Snake River Study,
dissolved oxygen (D.O.) was considered most important. Dissolved
oxygen concentrations are critical relative to the water quality
standards which were established to protect the fisheries.
Linked closely with D.O. is temperature which will be discussed
in the next section.
The first data evaluated for this report was collected
from March 1968 through August 1969 by the Pollution Surveillance
Branch, Northwest Regional Office, FWPCA. Stations sampled on
the Snake River are located at Weiser; below Brownlee, Oxbow
and Hells. Canyon Dams; and near the mouth of Asotin Creek. Data
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TABLE 7
WATER SPILLED IN CFS-MARCH, APRIL AND MAY, 1969
AT BROWNLEE, OXBOW, AND HELLS CANYON DAMSi/
1
2
3
4
5
6
7
8
9
10
11
12
13
14,
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
a/
Brown lee
36,205
38,203
35,173
28,750
19,938
37,154
31,260
26,875
34,219
24,760
29,708
15,931
29,063
29,675
33,729
36,979
34,883
39,938
22,266
16,146
26,250
33,958 .
32,478
30,833
33,021
28,854
26,666
28,496
40,000
44,666
46,604
Idaho Power
March
Oxbow '
8,115
18,938
12,188
7,656
2,656
15,000
113
5,000
11,701
6,953
8,500
13,188
10,387
10,688
12,000
12,000
13,875
15,229
10,064
1,333
6,545
18,000
14,304
13,385
13,802
8,615-
4,567
8,229
28,643
28,646
25,333
Data
Hells Canyon
7,400
7,400
7,400
7,050
2,250
11,500
7,849
3,750
3,750
3,750
9,750
14,750
14,750
14,156
11,500
11,500
11,500
12,463
3,329
-0-
1,885
4,500
10,354
' 7,250
8,500
2,396
-0-
6,635
15,000
15,000
17,452
Brownlee
45,000
47,969
46,125
45,000
46,667
50,000
36,250
48,750
44,166
41,458
45,000
49,688 '
52,500
47,746
42,146
• 44,292
39,167
' 37,708
36,854
40,240
' 38,000
36,250
34,520
31,375
35,781
25,404
26,357
28,233
25,510
19,735
April
Oxbow
29,458
28,229
26,806
31,365
34,042
39,000
19,399
29,438
24,388
20,208
23,625
33,698
31,042
2-5,792
25,250
22,375
16,708
14,438
14,250
22,177
15,420
14,187
14,583
14,028
15,229
12,458
10,000
6,250
6,000
9,208
Hells Canyon
20,000
19,500
18,000
18,667
17,875
17,000
17,000
17,000
17,000
19,333
21,000
21,000
21,000
21,000
21,000
21,000
14,446
8,000
'8,250
8,000
8,958
8,000
8,000
8,000
•3,954
-0-
-0-
-0-
-0-
-0-
Brownlee
21,933
18,573
7,510
8,281
12,396
27,710
40,000
36,822
38,490
35,000
38,333
31,146
24,792
18,750
25,000
20,771
22,813
25,833
21,563
22,313
24,167
5,000
-0-
-0-
3,073
3,315
-0-
-0-
-0-
-0-
-0-
May
Oxbow
7,250
7,934
-0-
-0-
-0-
9,167
15,781
16,458
16,875
15,000
17,500
14,313
4,938
3,614
4,542
5,250
4,833
5,917
6,365
4,396
5,041
-0-
-0-
-0-
-0-
1,146
-0-
-0-
-0-
-0-
-0-
Hells Canyon
. -0-
-0-
-0-
-0-
-0-
6,333
12,000
12,000
12,000
12,000
12,000
8,292
2, 300
2,300
2,300
2,300
2,300
2,300
2,300
2,300
767
2,979
3,400
3,260
5,854
.-0-
-0-
-0-
-0-
-0-
-0-
-------
30
from these stations are contained in Tables 8 through 12. The
average annual D.O. levels were 10.9, 7.5, 8.8, 7.9, and 10.6 mg/1
for Weiser, Brownlee, Oxbow, Hells Canyon and the Asotin stations,
respectively. Summer D.O. values for the same stations average
9.5, 5.8, 6.9, 6.1, and 9.2 mg/1. Comparison of the D.O."s
at Weiser and Brownlee shows a 31 percent reduction annually,
and a 39 percent reduction during the summer months through
Brownlee Reservoir. A slight increase in D.O. through Oxbow
Reservoir is offset by an almost equal reduction through Hells
Canyon Reservoir, leaving the D.O. concentration about the same
below Hells Canyon Dam as below Brownlee Dam. Values for
Asotin show an increase over those for the Hells Canyon station.
This is due to atmospheric reaeration plus dilution from high
quality tributaries such as the Salmon and Imnaha Rivers.
The first phase of the 1968-69 FWPCA field surveys involved
the installation of continuous recording monitors for D.O. and
temperature. These monitors produced a considerable amount of
data which were reduced and tabulated for daily maximums,
minimums, and averages. This tabulated data can be found in
the Appendix. The data for the Brownlee monitor shows an
average D.O. of 5.2 mg/1 for the days of record. During this
period the daily average ranged from 1.6 to 10.1 mg/1. Spillage
at Brownlee Dam, which commenced on August 17 and ended on
-------
TABLE 8
STORE! DATA--WEISER
DATE
FROM
TO
68/03/19
68/04/03
68/04/24
68/05/23
68/06/05
68/06/24
68/07/24
68/08/08
68/08/21
68/09/04
68/09/18
68/10/01
68/10/16
68/10/30
68/11/13
68/12/03
69/01/08
69/02/05
69/03/11
69/04/08
69/06/26
TIME DEPTH
OF
DAY FEET
16
15
09
14
oo"
16
07
06
12
10
11
08
12
07
14
14
09
12
08
14
17
00
00
30
30
15
15
30
15
30
15
20
30
30
45
30
15
00
00
15
15
00
00010
WATER
TEMP
CENT
9.0
9.9
13.0
17.0
19.9
25.0
22.5
21.0
17.6
18.0
18.5
16.0
11.5
10.0
8.3
6.0
3.0
1.9
4.5
9.1.
18.6
00300 00301
DO DO
SATUR
MG/L PERCENT
14.1
13.3
12.2
11.0
9.6
12.0
8.1
8.0
7.8
10.3
10,8
9.4
11.2
9.9
10.3
12.2
12.3
12.3
11.9
10.1
14.2
112.0
154.0
99.0
95.0
87.0
117.0
123.0
101.0
110.0
94.0
94.0
105.0
98.0
95.0
99.0
94.0
162.0
00665 70507 00610 00625 00945 00070 31503
PHOS-T PHOS-T AMMONIA TOT KJEL SULFATE TURB COLIFORM
P-WET ORTHO NHS-N N $04 JKSN DLY ENDO
MG/L MG/L-P MG/L MG/L MG/L JU MF/100ML
0.10
0.09
0.04
0.16
0.08
0.16
0.19
0.28
0.28
0.16
0.14
0.17
0.09
0.08
0.15
0.06
0.12
0.13
0.10
0.30
0.02
0.042
0.026
0'.022
0.024
0.012
0.029
0.031
0.079
0.093
0.065
0.017
0.017
0.017
0.027
0.050
0.038
0.120
0.079
0.041
0.068
0.015
0.100
0.100K
O.'IOOK
0.080
0.050K
0.010K
0.080
0.040
0.040
0.005K
0.005K
0.005K
0.010K
0.010K
0.030
0.030
0.030
0.010K
0.070
0.040
0.700
0.900
0.700
1.100
1.200
1.000
0.900
0.900
1.200
1.000
0.730
0.600
0.700
0.300
0.500
0.500
0.400
0.700
1.100
38
37
36
44
38
39
51
44
50
45
55
54
48
44
28
17 -
38
42
7
9
8
18
17
35
30
15
5
6
3
2
16
1
15
15
10
41
27
310
383
4700
2900
2400
3100
2400
1 1900
13600
7200
1300
6000
3700
9400
100K
2800
6600
1100
16100
3200
1600L
-------
TABLE 9
STORE! DATA—BROWNLEE
DATE
FROM
TO
68/07/23
68/08/06
68/08/13
68/08/21
68/09/04
68/09/18
68/10/01
68/10/16
68/10/30
68/11/13
68/12/04
69/01/08
69/02/05
69/03/10
69/04/10
69/04/15
69/04/29
69/05/22
69/06/26
00010
TIME DEPTH WATER
OF TEMP
DAY FEET CENT
07
14
14
16
11
14
11
15
10
17
08
15
14
20
15
16
10
07
07
08
19
00
15
45 0003
00
50
30
00
00
30
00
00
20
00
00
45 0001
00 0001
00
30 0001
55 0015
30
00
14.3
23.0
22.4
20.8
21.0
20.0
19.5
15.0
14.0
11.1
8.0
6.0
2.9
5.0
10.6
11.1
10.0
11.6
11.3
16.3
19.7
00300 00301
DO DO
SATUR
MG/L PERCENT
4.8
5.4
5.8
9.7
3.4
4.3
4.6
4.8
5.5
11.5
6.2
11.1
14.5
14.6
12.6
9.6
9.4
0.6
0.3
9.7
9.0
49.0
66.0
114.0
40.0
49.0
52.0
50.0
56.0
110.0
55.0
94.0
114.0
121.0
122.0
104.0
1Q4.0
00665 70507 00610 00625 00945 00070 31503
PHOS-T PHOS-T AMMONIA TOT KJEL SULFATE TURB COLIFORM
P-WET ORTHO IMHS-N N 504 JKSN DLY ENDO
MG/L MG/L-P MG/L MG/L MG/L JU MF/100ML
0.07
0.03
0.06
0.06
0.09
0.08
0.13
0.07
0.07
0.06
0.11
0.15
0.12
0.09
0.11
0.06
0.04
0.051
0.013
0.029
0.040
0.082
0.084
0.065
0.060
0.049
0.080
0.090
0.096
0.049
0.071
0.018
0.019
0.050K
0.020
0.140
0.060
0.090
0.035
0.055
0.010
0.010K
0.020
0.040
0.080
0.050
0.140
0.080
0.300
0.400
0.700
0.500
0.600
0.520
0.590
0.600
0.500
0.400
0.800
0.300
0.500
0.600
0.500
0.500
1
1
2
7
12
IK
IK
0.5
14
3
49 3
37 15
26 5
26 2
5
100K
80
100
-------
TABLE 10
STORET DATA—OXBOW
DATE
FROM
TO
68/08705
68/08/13
68/08/21
68/09/04
68/09/18
68/10/01
68/10/16
68/10/30
68/11/13
68/12/03
69/01/08
69/02/05
69/02/11
69/03/10
69/04/10
69/04/15
69/04/29
69/05/22
69/06/26
00010
TIME DEPTH WATER
OF TEMP
DAY FEET CENT
18
19
18
13
17
12
17
11
19
19
16
15
15
19
14
15
11
08
09
10
19
15
05 0003
00
15
20
00
00
10
00
20
00
00
00
20
50 0001
15 0030
25
40 0015
00 0001
15
45
21.0
22.0
20.8
21.0
20.0
20.0
15.0
14.0 .
11.0
9.0
6.5
2.8
5.0
10.8
10.5
10.3
11.6
11.4
16.3
19.2
00300 00301
DO DO
SATUR
MG/L PERCENT
6.0
6.2
8.8
6.5
5.6
6.6
6.0
5.3
7.8
8.2
11.2
14.7
14.5
12.1
12.5
12.7
0.6
11.5
11.6
8.5
70.0
103.0
76.0
65.0
76.0
62.0
54.0
74.0
75.0
96.0
115.0
120.0
120.0
125.0
97.0
00665 70507 00610 00625 00945 00070 31503
PHOS-T PHOS-T AMMONIA TOT KJEL SULFATE TURB COLIFORM
P-WET ORTHO NH3-N N S04 JKSN DLY ENDO
MG/L MG/L-P MG/L MG/L MG/L JU MF/100ML
0.04
0.05
0.06
0.09
0.07
0.11
0.07
0.09
0.06
0.08
0.12
0.09
0.09
0.11
0.07
0.04
0.018
0.024
0.034
0.081
0.059
0.091
0.063
0.070
0.056
0.073
0.060
0.110
0.004
0.048
0.071
0.031
0.023
0.010
0.030
0.020
0.060
0.030
0.050
0.060
0.010K
0.010K
0.060
0.080
0.030
0.130
0.060
0.400
0.400
0.600
0.600
0.520
0.590
0.330
0.500
0.500
0.500
a. 400
0.400
0.800
0.500
0.300
1
2
13
15
IK
IK
0.5
13
4
49 5
37 15
28 4
25 3
100
115
130
-------
TABLE 11
STORET DATA—HELLS CANY0N
DATE
FROM
TO
68/07/24
68/08/06
68/08/14
68/08/21
68/09/Q4
68/09/19
68/10/01
68/10/16
68/11/13
68/11/30
68/12/03
69/01/08
69/02/11
69/03/10
69/04/10
69/04/15
69/04/28
69/05/22
69/06/26
00010
TIME DEPTH WATER
OF TEMP
DAY FEET CENT
14
08
15
20
15
09
14
16
18
12
17
17
16
18
14
08
19
19
12
21
00
30
15 0003
00
00
30
15
15
00
30
30
30
00
15
10 0001
00
00 0001
45 0001
15
00
21.7
18.0
21.0
19.9
21.0
18.7
20.0
15.5
11.0
14.5
9.5
6.5
5.1
10.5
9.3
11.2
11.5
16.7
18.9
00300 00301
DO DO
SATUR
MG/L PERCENT
7.0
5.4
5.0
5.6
7.3
4.7
6.4
5.8
7.6
5.9
8.2
12.0
13.4
12.0
13.0
11.4
0.5
12.1
7.3
83.0
60.0
64.0
85.0
53.0
73.0
60.0
72.0
60.0
75.0
102.0
111.0
124.0
131.0
82.0
'00665 70507 00610 00625 00945 00070 31503
PHOS-T PHOS-T AMMONIA TOT KJEL SULFATE TURB COLIFORM
P-WET ORTHO NH3-N N S04 JKSN DLY ENDO
MG/L MG/L-P MG/L MG/L MG/L JU MF/100ML
0.05
0.04
0.06
0.05
0.09
0.08
0.09
0.08
0.07
0.09
0.08
0.13
0.09
0.12
0.08
0.05
0.024
0.024
0.029
0.026
0.075
0.068
0.072
0.073
0.055
0.067
0.074
0.054
0.002K
0.052
0.066
0.026
0.021
0.050K
0.050
0.060
0.010
0.060
0.015
0.010
0.050
0.010K
0.030
0.060
.0.010
0.150
0.030
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
.400
.400
.500
.500
.500
.460
.780
.600
.600
.500
.600
.500
.500
.300
.400
IK
1
2 155
10
z
IK 660
IK
0.5
13
49 4
31 12
28 3
24 5
-------
TABLE 12
STORE! DATA—ASOTIN
DATE
FROM
TO
69/02/12
69/03/12
69/04/03
69/05/14
69/06/11
69/07/09
69/08/04
69/08/26
TIME DEPTH
OF
DAY FEET
11 50
10 55
12 30
16 15
10 10
12 00
20 30
11 45
00010
WATER
TEMP
CENT
4.2
8.8
11.9
15.5
19.5
21.3
22.0
00300
DO
MG/L
12.6
13.2
11.4
10.8
9.5
9.6
8.9
8.7
00301
DO
SATUR
PERCENT
100.0
102.0
97.0
106.0
102.0
102.0
00665
PH'OS-T
P-WET
MG/L
0.12
0.09
0.16
0.10
0.12
0.03
0.06
0.05
70507
PHOS-T
ORTHO
MG/L-P
0.082
0.052
0.052
0.030
0.035
0.014
0.035
00610
AMMONIA
IMH3-N
MG/L
0.070
0.010
0.110
0.060
0.030
0.030
00625
TOT KJEL
N
MG/L
0.400
0.500
0.900
0.400
0.500
0.200
00945
SULFATE
S04
MG/L
28
39
15
12
17
22
37
00070
TURB
JKSN
JU
20
Z
13
10
IK
1
1
31503
COL I FORM
DLY ENDO
MF/100ML
1560
145
600
1430
1080
400L
-------
36
September 3, 1968, caused an average increase of 80 percent over
average D.O. values measured when no spilling occurred. Data
from Oxbow Dam show a daily average D.O. of 6.1 mg/1 with a
daily average high of 9.0 mg/1 and a daily average low of
4.3 mg/1. D.O. values at Oxbow Dam show an increase for
Brownlee which is due partially to the fact that the Brownlee
monitor ran 60 days compared with 48 at Oxbow.
At the Hells Canyon station, 39 days of record were compiled.
During this time the average D.O. was 6.7 mg/1 with a daily
average high and low of 9.2 and 4.4 mg/1, respectively.
Of interest at Brownlee was the great depression in D.O.
measured during the morning hours when high flows were needed
for power peaking. The low values of D.O. can be seen most
dramatically for August 25 through 29, 1968, when daily minimum
averaged 3.3 mg/1, which was only 46 percent of the daily average
for the same period.
During the four weeks of field surveys, D.O. and temperature
profiles were completed for Oxbow and Hells Canyon Reservoirs
plus a station located at the Brownlee log boom. These profiles
are shown in Figures 2 through 6. Figure 2 for Brownlee Reservoir
shows D.O. decreasing with depth for all four sampling periods.
The August 13, 1968, survey shows great increase in D.O. in the
top 30 feet which is due to algal activity. Figure 2 also shows
the D.O. profiles in percent saturation. Except f6r the areas
-------
FIGURE 2 Isotherms, Dissolved Oxygen and Dissolved Oxygen
Station 1 (Brownlee Log Boom)
Saturation Profiles for
-------
FIGURE 3 Dissolved Oxygen Profiles for Oxbow Reservoir
-------
FIGURE 4 Dissolved Oxygen Saturation Profiles for Oxbow Reservoir
-------
FIGURE 5 Dissolved Oxygen Profiles for Hells Canyon Reservoir
-------
FIGURE 6 Dissolved Oxygen
Reservoir
Saturation Profiles for Hells Canyon
-------
42
having high algal activity, the quality of water in Brownlee
Reservoir was below the Standards' minimum D.O. criteria of
75 percent saturation. Figures 3 and 4 show the D.O. and D.O.
saturation profiles for Oxbow Reservoir. These profiles show
that during the survey period the greater portion of the
reservoir had a D.O. level of 5 to 6 mg/1. Only during the
August 1968 survey was a great difference in D.O. observed
between the surface and bottom waters of Oxbow Reservoir. The
D.O. percent saturation profiles in Figure 4, like those for
Brownlee, show that the whole reservoir, except at the surface
near the face of the dam where algal activity was highest, was
below the standard of 75 percent saturation.
Hells Canyon Reservoir had the greatest gradient of D.O.
values as can be seen in Figure 5. This reservoir had a
thermocline which ranged from 100 to 175 feet deep, below
which the D.O. was zero. As in Oxbow and Brownlee, algal
activity near the dam face caused D.O. values to exceed 100
percent saturation in the surface layers during the dry 1969
survey. Only in this area did the water in Hells Canyon
Reservoir meet the D.O. Standard of 75 percent saturation.
The D.O. saturation profiles for Hells Canyon Reservoir are
shown in Figure 6. During the study period, the majority of
the reservoir had a D.O. value of 5 to 6 mg/1.
-------
43
Sampling was performed for a distance of six miles below
Hells Canyon Dam to see how long it would require low D.O. water
from Hells Canyon Dam to reach 100 percent saturation. Only
six miles of river could be sampled as Wild Sheep Creek Rapids
was not navigable. Table 13 contains the D.O. data obtained from
four trips below Hells Canyon Dam. The range of D.O. increase
over the six mile reach was only 0.9 to 1.4 mg/1. In two cases
of the four, the percent saturation at Wild Sheep Creek was
above the Standard of 75 percent.
Temperature
Three approaches were taken to evaluate effects of the
three Idaho Power Projects on temperature. These involved
sampling by the FWPCA Surveillance Branch, continuous monitors
below the dams, and temperature profile studies.
Surveillance sampling was done at five stations in the
study area. These were located on the Snake River at Weiser,
below Brownlee, Oxbow, and Hells Canyon Dams, and at Asotin
Creek. Data for this sampling are provided in Tables 8 through 12,
Comparison of these tables shows that the annual temperature
averages 13.3, 14.0, 13.9, 14.7 and 14.7° C. for the stations
at Weiser, Brownlee, Oxbow, Hells Canyon, and Asotin,
o o
respectively. An increase of 0.7 C. through Brownlee and 0.8 C.
for Hells Canyon Reservoirs is noted with essentially no change
in Oxbow Reservoir. In 1968, summer temperatures for Weiser,
Brownlee, Oxbow, and Hells Canyon averaged 20.4, 20.3, 21.2, and
20.3 c. respectively.
-------
TABLE 13
DISSOLVED OXYGEN LEVELS BELOW HELLS CANYON DAM
Station
Hells Canyon Tail race
Hells Canyon Creek
Stud Creek
Brush Creek
Halfway between Brush
Battle Creek
Wild Sheep Creek
River
Mile
247
246
245
244
& Battle Creek 243
242
241
.8
.8
.9
.7
.5
.2
.4
8/14/68
D.O.
mg/1 XSat,
4.8
4.7
5.8
6.3
6.2
6.4
6.2
56
56
66
73
72
74
72
9/18/68
D.O.
, mg/1 %Sat.
4
5
5
5
5
6
.9
.2
.7
.8
.9
.0
58
61
67
68
69
70
10/16/68
D.O.
mg/1 %Sat.
6.0
6.2
6.2
6.8
6.8
6.8
6.9
66
68
68
75
75
75
76
8/10/69
D.O.
mg/1 %Sat.
5.7
6.0
6.2
6.5
6.5
6.7
7.0
70
72
74
78
78
83
86
Increase in D.O. 1.4 16 1.1 12 0.9 10 1.3 16
Total Distance 6.4
-------
45
Over the total period monitored, 87 percent of the data
o
for all three stations showed a diurnal fluctuation of 2 C. or
less between maximum and minimum temperatures, and 83 percent
o
of the data showed a diurnal fluctuation of 1 C." or less
between maximum and minimum temperatures. Whereas D.O.'s below
Brownlee fluctuated considerably during power peaking at the
dam, no apparent change in temperature was noted. Tabulated
data for the temperature monitors is provided in the Appendix.
The data provided by t,he temperature monitors were verified
by running temperature profiles in the three reservoirs. Figure
2 shows the temperature profile at the Brownlee Dam log boom.
Data from four different surveys show the top 100 to 150 feet of
the reservoir to be nearly isothermal. A thermocline was found
at this station during the August and September 1968 surveys but
was absent during the October 1968 and August 1969 surveys. The
thermocline was located in both instances at approximately 140
feet. Figure 7 shows the isotherms for Oxbow Reservoir. Except
for the August 1968 survey, temperature differences from water
o
surface to bottom were less than 2 C. No thermocline was
observed in Oxbow Reservoir which is only 105 feet deep. The
isotherms for Hells Canyon Reservoir are shown in Figure 8.
This reservoir, like Brownlee and Oxbow, was found to be
nearly isothermal in the top 150 feet. During all surveys a
-------
FIGURE 7 Isotherms for Oxbow Reservoir
-------
FIGURE 8 Isotherms for Hells Canyon Reservoir
-------
48
thermocline was found at Hells Canyon which affected only a small
portion of the reservoir, as can be seen in Figure 8.
From all the data evaluated it can be concluded that during
the summer months most of the water in the three reservoirs
was of approximately the same temperature; if a thermocline
existed, it was at least 140 feet below the surface.
Nutrients'and Algal Production
There is direct evidence that waters of the Snake River
have high enough nutrient levels to support abundant growths
of algae. Kari and Galloway report "great algal blooms in
most areas" between Adrian, Oregon and Weiser, Idaho on
August 22 and 23, 1961. (7) They also state: "The Snake River
carried an exceptionally heavy load of algae in suspension.
Dominant genera at the time of the survey were Anabaena,
Pediastrum, Spirogryra, Aphanizomenon, Staurastruem, and
Anacystis." (7) Three of the genera are "blue-greens" and are
indicators of enriched waters.
Ebel and Koski report that "the large phytoplankton blooms
in Brownlee Reservoir throughout the summer indicated that high
turbidity did not seriously hinder primary production at the
surface." (5)
-------
49
Area residents report that the second year after filling
seemed to be the worst as far as algal production was concerned.
The reports were partially verified for Hells Canyon Reservoir
which was relatively free of algal blooms in 1968 but which
had profuse growths in 1969. A floating mat of blue-greens
two to three inches in thickness was observed at the downstream
end of the reservoir during the August 1969 survey.
Algal growths cause aesthetic problems besides interfering
with recreational and municipal uses. Another effect on
reservoirs that are rich in algae is that dead or dying algal
cells settle into the hypolimnetic (below the thermocline)
waters. Decomposition of these cells consumes the D.O. supply.
Because there is no atmospheric reaeration and because there is
no photosynthetic activity at these levels, the D.O. concentra-
tions may go to zero.
Algal-producing nutrients are becoming increasingly important
as water quality indicators. As previously mentioned, the Snake
River in the study area supports abundant algal growths. In
evaluating the effect of the three reservoirs on water quality,
nutrient transport and removal becomes important. To accomplish
this, the year of data collected at Weiser and below each of
the three dams was evaluated. Tables 8 through 11 contain this
data.
-------
50
For the stations at Weiser, Brownlee, Oxbow and Hells
Canyon, respectively, annual concentration averages were: total
phosphate .14, .08, .07, and .08 rag/1; orthosphosphate .04, .06,
.05, and .05 rag/1; ammonia nitrogen .04, .06, .05, and .04 mg/1
and total kjeldahl nitrogen .8, .5, .5, and .5 mg/1. It is
interesting to note the 43 percent removal of total phosphate and
3 percent removal of kjeldahl nitrogen in Brownlee Reservoir with
essentially no additional removal in Oxbow or Hells Canyon
Reservoirs. This can be explained by examining the turbidity
data which averages 15, 5, 6, and 4 Jackson Turbidity Units (JU)
for stations at Weiser, Brownlee, Oxbow, and Hells Canyon,
respectively. The 60 percent removal of turbidity in Brownlee
Reservoir must be related to the total phosphorus and kjeldahl
nitrogen removals, since these nutrients are found in suspended
organic solids. The soluble orthophosphate and ammonia nitrogen
concentrations are not reduced, however, as seen from a comparison
of Tables 8 through 11. After the initial removal of the nutrients
associated with the settleable organic solids, little additional
removal can be expected. It is also apparent that enough nutrients
exist in the soluble form to promote the growth of algae in
downstream Snake River reservoirs.
During the August 1969 survey, samples were taken to see
how nutrient levels vary with depth in a stratified reservoir.
-------
51
Table 14 contains the data from this survey. For the Eagle
Bar Station in Hells Canyon Reservoir, at depths of 3, 75, and
195 feet, respectively, total phosphates were 0..23, 0.08, and
0.10 mg/1, while orthophosphates were 0.031, 0.036, and 0.002
mg/1. The high values at the 3-foot level were due to the
presence of algal cells. Similarly, the kjeldahl nitrogen
values at the 3-foot level were 2.8 mg/1 compared to 0.4 mg/1
and 0.5 mg/1 at the 75 and 195-foot depths, respectively. The
low value for kjeldahl nitrogen at the 195-foot depth indicates
minimal organic deposits on the bottom. A significant deposit
would release ammonia and organic forms of nitrogen into the
overlying waters during decomposition.
Sulfates and Sulfides
There is considerable concern over the possibility of large
fish kills due to hydrogen sulfide (H_S) production in the reser-
voirs on the Middle and Lower Snake River. This production of
H~S results from the reduction of sulfate and sulfites to
sulfides under anaerobic (without oxygen) conditions. The FUS
produced under these conditions is toxic to fish and aquatic life
at concentrations of 0.1 mg/1 as reported by Haydu, et al.(2,6)
H-S can also affect the use of water for domestic sources at
concentrations of 0.05 mg/1 or greater.
In contrast to H-S, sulfates are relatively non-toxic;
however, a maximum concentration of 250 mg/1 has been set for
-------
TABLE 14
Chemical Parameter Profiles for Study Area
8/19 - 21/69
Station
Brown lee
Log Boom
Oxbow Log
Boom
Eagle Bar
Depth
Ft.
15
165
45
3
75
195
D.O.
mg/1
6.0
0.0
4.7
10.0
5.5
0.0
Sulfate
mg/1
60
44
60
52
56
26
Sulfide
mg/1
.14
.18
.12
.24
.12
.36
Total
Phosphorus mg/1
_
-
.23
.08
.10
Orthophosphorus
mg/1
-
.031
.036
.002
NH3-N N02-N NOo-N Kjeldahl -N
mg/1 mq/1 mq/T mq/1
— — _ ..
-
.04 .01 .08 2.8
.04 .02 .18 .4
.5
Wild Sheep 3
Creek
7.0 52
12
.17
.032
.07
.02
.18
.4
-------
53
sulfates in the U.S. Public Health Service Drinking Water
Standards. This value was based on the potential laxative
effect to new users.
Both sulfates and sulfides were measured in the Middle Snake
during the August 1969 survey. The determination of sulfides
is not selective for H_S, but measures all forms of sulfides
(colloidal, soluble and gaseous). Table 14 contains the results
of these analyses. The level of sulfates in the upper strata
of the three reservoirs, as well as below Hells Canyon Dam,
ranges from 44 to 60 mg/1. The sulfides also are fairly con-
sistent, ranging from 0.12 to 0.24 mg/1. Because the upper
strata of the reservoirs contain dissolved oxygen, these sulfide
values of 0.12 to 0.24 mg/1 do not include any H2S but consist
only of soluble and/or colloidal forms. .The dissolved oxygen
at 195 feet at the Eagle Bar Station in Hells Canyon was
zero, however, and the samples collected had a strong odor of
H~S. The presence of H-S was further verified by the reduction
of sulfates from 52 to 26 mg/1 and the increase in sulfides to
0.36 mg/1. It therefore appears that H-S is a problem in Hells
Canyon Reservoir whenever dissolved oxygen is absent.
Dissolved Nitrogen
Dissolved nitrogen (D.N.) super saturation in water, while
not a new phenomenon, is causing increasing problems relative
to fisheries. The supersaturation of D.N. may lead to embolism
(gas-bubble disease) resulting in large fish kills.
-------
54
Dissolved nitrogen supersaturation seems to occur most
frequently below dams where excess water which is spilled
entrains air in its mass and plunges to depths where increased
static pressure causes a supersaturated condition to occur.
From data gathered it appears that the time required for the
D.N. concentrations to return to equilibrium is fairly long.
In the Middle Snake very little change in D.N. was measured
from Brownlee to below Hells Canyon Dam, a distance which
required 3 days flow time at a discharge of 40,000 cfs.
While it is agreed that D.N. supersaturation is a problem,
agreement cannot be reached either on a reliable method for
analysis or on a physiological threshold concentration. Two
methods of analysis are presently being used. One uses a
Van Slyke gas blood analyses,(11) and the other a gas
partitioner.(9) While the analytical difference between these
methods is not known, it probably is less than that caused by
non-uniform sample preservation. A number of threshold values
of D.N. have been reported, ranging from 104 to 120 percent of
saturation.
During the spring of 1969 sampling for D.N. on the Middle
Snake was performed. Four different surveys were run, one
by the Bureau of Commercial Fisheries (BCF) and three by FWPCA.
Data from these four surveys are presented in Tables 15 through 18.
-------
TABLE 15
Analysis of Dissolved Gases for the Middle Snake River a/
March 29, 1969 b/
Location
Brown lee Dam/Forebay
Brownlee Dam Forebay
Oxbow Hatchery Intake
Oxbow Hatchery East
Pond
Oxbow Hatchery West
Pond
Hells Canyon Dam
Forebay
Grand Ronde
Depth
Ft.
10
30
Surface
Surface
Surface
Surface
Surface
Temp.
°C
8.0
7.6
8.0
8.2
8.2
7.4
7.7
D.O.
mg/1
9.8
13.6
13.7
12.1
12.2
13.3
12.3
.Nf/
mqVl
18.5
22.4
22.7
19.9
19.9
22.8
20.5
%N9
Sat.
104
116
118
104
104
117
106
a/ Bureau of Commercial Fisheries Data
b/ Discharge at Hells Canyon gauge 49,896 cfs.
£/ Analyzed by Van Slyke Gas Blood Analyzer ll/
-------
56-
The first survey was conducted on March 29, 1969 by the
BCF. Table 15 contains the data for this survey. As can be
noted an increase in D.N. saturation can be seen from the
Brownlee forebay (104 to 116 percent) to the Oxbow Hatchery
(118 percent), which is located below Oxbow Dam at the head
end of Hells Canyon Reservoir. Essentially no change in D.N.
saturation was measured in Hells Canyon Reservoir. Table 7
shows that spillage for the days sampled was quite high
(40,000, 29,000, and 15,000 cfs at Brownlee, Oxbow and Hells
Canyon Dams, respectively).
Table 16 contains data from the second survey on April 10,
1969. This survey showed a substantial increase in D.N.
saturation, from 95 to 97 percent above Brownlee to 121 percent
below Brownlee. A slight decrease is noted through Oxbow
Reservoir (114 to 116 percent above the dam). From here to
below Hells Canyon Dam only minor changes were measured, with
a saturation value of 117 percent recorded at the station below
the dam. Spillage for the days sampled was about the same as
for the March survey (41,000, 10,000, and 19,000 cfs at Brownlee,
Oxbow, and Hells Canyon Dams respectively).
The third survey was conducted on April 24 and April 30, 1969.
Table 17 contains the data for this survey. Very little change
is seen through Oxbow Reservoir and a decrease occurs at Oxbow
-------
TABLE 16
Analysis of Dissolved Gases for the Middle Snake River
April 10, 1969a/
Location
Above Brownlee Dam
Above Brownlee Dam
Below Brownlee Dam
Above Oxbow Dam
Below Oxbow Dam
Above Hells Canyon Dam
Above Hells Canyon Dam
Below Hells Canyon Dam
Depth
Ft.
Surface
30
Surface
30
Surface
Surface
30
Surface
Temp .
oc
11.1
10.7
10.6
10.5
10.8
10.7
10.5
10.4
D.O.b/
mg/1
9.6
9.4
12.6
12.5
12.1
12.0
12.0
13.0
%D.O.
Sat.
87
85
114
113
109
112
108
116
N2c/
mg/1
16.8
17.3
21.5
20.3
20.0
20.5
20.1
21.0
%N«
Sat.
95
97
121
114
112
115
112
117
Argon
mg/1
0.6
0.6
0.8
0.8
0.8
0.8
0.7
0.8
a/ Discharge at Hells Canyon gauge = 55,000 cfs.
b/ Field Analysis
£/ Analyzed with Gas Partitioner 9_/
-------
TABLE 17
Analysis of Dissolved Gases for the Middle Snake River
April 30, 1969a/
Location
Above Brownlee Dam d/
Below Brownlee Dam
Above Oxbow Dam
Below Oxbow Dam
Above Hells Canyon Dam
Above Hells Canyon Dam
Below Hells Canyon Dam
Above Grande Ronde River
Depth
Ft.
15
Surface
15
Surface
Surface
30
Surface
Surface
Temp.
oc
11.3
11.6
11.6
11.4
11.5
11.5
11.2
10.5
D.O.b/
mq/1
9.7
12.3
12.1
11.5 §/
11.2
11.4
11.4
11.0
%D.O.
Sat.
89
113
111
106
105
104
104
97
N2c/
mg7l
17.5
20.2
20.0
18.4
18.8
19.2
18.7
15.8
S°a?.
99
115
114
-106
107
110
106
85
Argon
mg/1
0.6
0.8
0.8
0.7
0.7
0.7
0.7
0.7
a/ Discharge at Hells Canyon gauge = 29,900 cfs.
b/ Field analysis
c/ Analyzed with Gas Partitioner 9_/
d/ Sampled April 24, 1969, Discharge at Hells Canyon gauge = 40,500 cfs,
e/ Lab analysis
-------
59
Dam, going from 114 percent saturation above the Dam to 106
percent below the Dami. Essentially no change is noted in Hells
Canyon Reservoir or over Hells Canyon Dam. Of interest in this
survey is the drop in D.N. saturation from below Hells Canyon
Dam (106 percent) to the Grande Ronde (85 percent). The distance
between these stations is 78 river miles, and two large tributaries,
the Salmon and Imnaha, enter in this reach. Spillage for the
days sampled was reduced from the first two surveys (31,000,
9,000, and zero cfs for Brownlee, Oxbow, and Hells Canyon Dams,
respectively).
Table 18 contains the data for the final survey which was
conducted on May 22, 1969. Data from this survey shows essentially
no change over Brownlee Dam, but a big jump from the head of
Oxbow Reservoir (100 percent saturation) to the Dam (121 percent).
This change can be explained by looking at the spillage records
and noting that, on the day sampled, the spillage at Brownlee was
only 5,000 cfs, but the previous day's spillage ranged from
21,000 to 24,000 cfs. Presumably the high D.N. above Oxbow
Dam was the result of the increase due to spillage at Brownlee
Dam for three preceding days. Essentially no change is noted
over Oxbow where no spillage was taking place. This survey brought
out the large change noted over Hells Canyon Dam where the D.N.
saturation increased from 115 to 135 percent, with a spillage
of only 3,000 cfs.
-------
60
In general, it can be concluded that the increase in D.N.
saturation due to spillage is a function of the depth of plunge
in the pool and amount of water spilled. It is also shown that
the return to equilibrium is fairly slow, since no appreciable
change could be seen from one end of a reservoir to the other.
-------
TABLE 18
Analysis of Dissolved Gases for the Middle Snake River
May 22, 1969a/
Location
Above Brownlee Dam
Above Brownlee Dam
Below Brownlee Dam
Above Oxbow Dam
Above Oxbow Dam
Below Oxbow Dam
Above Hells Canyon Dam
Above Hells Canyon Dam
Below Hells Canyon Dam
a/ Discharge at Hells
b_/ Field analysis
c/ Analyzed with Gas
Depth
Ft.
Surface
30
Surface
Surface
30
Surface
Surface
30
Surface
Canyon gauge = 23,000
Parti ti oner 9_/
Temp.
°C
17.5
16.8
16.3
17.0
16.0
16.3
17.3
16.6
16.7
cfs.
D.O.b/
mg/1
12.1
8.9
9.7
11.8
11.0
11.6
11.0
10.5
12.1
%D.O.
Sat.
127
92
100
123
113
118
116
108
125
N2c/
mg/1
15.0
14.9
16.0
18.9
19.1
19.5
17.9
18.1
21.4
%N2
Sat.
100
94
100
121
119
123
114
115
135
Argon
mg/1
0.8
0.6
0.6
0.7
0.7
0.7
0.6
0.7
0.7
-------
DEFINITION OF TERMS
Algae--Simple plants, many microscopic, containing chlorophyll.
Benthic Region—The bottom of all waters.
BOD--Biochemical Oxygen Demand. A measure of the amount of
oxygen required for the biological decomposition of dissolved
organic solids to occur under aerobic conditions and at a
standardized incubation time and temperature.
cfs--Cubic feet per second.
Epilimnion--That region of a body of water that extends from
the surface to the thermocline and does not have a permanent
temperature stratification.
Hypolimnion--The region of a body of water that extends from
the thermocline to the bottom and is removed from surface
influence.
JU--Jackson unit, a measure of turbidity which was derived from
a Jackson candle turbidimeter.
mg/1--Milligrams per liter (1000 mg/l=lgm/l)
Orthophosphate--A stable form of phosphorus which is the only
available form for biological activity.
Phytoplankton--Plant microorganisms, such as algae, living
unattached in the water.
Plankton--Aquatic plant and animal organisms of small size,
mostly microscopic, that have relatively small powers of
locomotion or drift in the water subject to wave action and
currents.
Reservoir Overturn--In deep lakes and reservoirs, the seasons
induce a cycle of physical and chemical changes in the water
that are often conditioned by temperature. For a few weeks
in the spring and again in the autumn water temperatures may
be homogeneous from the top to the bottom. Vertical water
density is also homogeneous and it becomes possible for the
wind to mix the water, distributing nutrients and flocculent
bottom solids from the deeper waters. This is a period of
water overturn.
-------
64
Thermocline--The layer in a body of water in which the drop
in tenderature equals or exceeds 1 C. for each meter or
approximately 3 feet of water depth.
Total Kjeldahl Nitrogen--0rganic nitrogen and nitrogen in the
form of ammonia £NHo)» Does not include nitrogen in the form
of nitrates (NO- ) or nitrites (NO ~).
Total Phosphorus--Phosphorus in organic and inorganic forms.
Phosphorus and nitrogen are nutrients necessary for maintaining
biological growth.
-------
BIBLIOGRAPHY
1. Anonymous, 1968, Middle Snake River Water Resources
Development, Snake River Basin, Oregon-Idaho-Washington, U.S.
Department of the Interior, FWPCA, Northwest Region, Portland,
Oregon.
2. Anonymous, 1952, The Effects of Kraft Mill Waste Liquors
and Some of Their Components on Certain Salmonoid Fishes of
the Pacific Northwest, National Council for Air and Stream
Improvement, Inc., Technical Bulletins, No. 51.
3. Anonymous, 1968, Water Quality Control and Management--
Snake River Basin, U.S. Deparment of the Interior, FWPCA,
Northwest Region, Portland, Oregon.
4. Brezonik, Patrick L., Delfino, J.J., and Lee, G. Fred, 1969,
Chemistry of N and Mn in Cox Hollow Lake, Wisconsin, Following
Destratification, Journal of Sanitary Engineering Division,
ASCE.
5. Ebel, Wesley J. and Koski, C.H., 1967, Physical and Chemical
Limnology of Brownlee Reservoir 1962-64, Bureau of Commercial
Fisheries Biological Laboratory, Seattle, Washington.
6. Haydu, E.P., Amberg, H.R. and Dimick, R.E., 1952, The Effect
of Kraft Mill Waste Components on Certain Salmonoid Fishes of
the Pacific Northwest, TAPPI, Volume 35, (12).
7. Kari, E.N. and Galloway, R.J., 1961, Summary Report Water
Quality Studies, Brownlee Reservoir--Snake River, Working
Paper 16, Columbia Basin Proj., DHEW, PHS, Portland, Oregon.
8. Sawyer, C.N., 1952, Some New Aspects of Phosphates in Relation
to Lake Fertilization, Sewage and Industrial Wastes, 24, p.768.
9. Swinnerton, J.W. Linnerbom, V.J., and Check, C.H., 1962,
Determiniation of Dissolved Gases in Aqueous Solutions by Gas
Chromatography, Analytical Chemistry, Vol. 344, p. 483-485.
10. Symons, James M., Weibel, S.R., and Robeck, Gordon G., 1964,
Influence of Impoundments on Water Quality, A Review of
Literature and Statement of Research Needs, Public Health
Service Publication, No. 999 WP-18.
-------
66
11. Van Slyke, D.D., Dillon, R.T., and Margaria, R., 1934,
Solubility and Physical State of Atmospheric Nitrogen in
Blood Cells and Plasma, Journal of Biological Chemistry,
Volume 106, p. 571.
12. Wagner, R., 1960, Water Uses and Water Quality Interferences
With Water Uses — Snake River Basin, Working Paper No. 60,
Department of Health, Education, and Welfare, USPHS, Portland,
Oregon.
-------
APPENDIX
Dissolved Oxygen and Temperature Monitoring Data
-------
TABLE 1
MONITORING DATA
BELOW BROWNLEE DAM
DISSOLVED OXYGEN, mg/1
DATE
7/24/68
25
26
27
28
29
30
31
8/1/68
2
3
4
5
6
7
8
9
10
11
12
Max.
No Record
6.0
6.4
5.9
5.2
6.7
6.0
6.3
5.3
5.5
4.7
5.2
5.9
5.4
4.6
2.4
2.0
5.3
5.1
4.9
Min.
4.3
3.0
3.6
3.0
3.4
2.3
3.3
3.6
3.8
3.2
3.6
2.8
2.5
2.0
1.2
1.3
2.6
2.8
1.9
Ave.
5.3
4.8
4.9
4.8
5.3
4.8
4.8
4.3
4.3
3.9
3.9
3.8
3.3
2.6
1.8
1.6
4.1
3.8
4.4
TEMPERATURE ,
Max.
No
20
20
21
20
21
21
21
21
20
21
20
21
23
23
23
23
23
22
23
Min.
Record
18
16
17
17
16
16
16
17
17
17
17
17
22
18
18
19
19
19
18
uc
Ave.
19
19
20
19
19
19
19
20
20
20
20
21
22
23
22
22
22
21
21
-------
TABLE 1
MONITORING DATA
BELOW BROWNLEE DAM (Cont.)
DISSOLVED OXYGEN, mg/1
DATE
8/13/68
14
15
16
17
18 - 21
22
23
24 .
25
26
27
28
29
30
31
9/1/68
2
3
4
Max
6.9
5.9
6.2
Min..
1.9
2.4
4.9
10.1 4.1
10.2
No
9.6
9.6
9.6
9.2
9.2
9.3
9.5
9.5
No
No
No
No
No
3.4
10.1
Record
9.2
8.0
8.9
4.0
3.5
3.1
3.1
3.0
Record
Record
Record
Record
Record
2.3 .
Ave.
4.6
4.9
5.8
7.5
10.1
9.4
9.2
9.2
7.4
7.2
8.4
6.3
7.2
2.9
TEMPERATURE,
Max
23
23
23
23
23
No
22
22
22
22
22
21
21
21
21
21
22
21
21
21
Min.
19
19
21
22
21
Record
22
21
22
21
19
20
20
21
20
20
21
21
20
19
°C
Ave.
21
22
22
22
22
22
22
22
22
21
21
21
21
21
21
21
21
21
21
-------
TABLE 1
MONITORING DATA
BELOW BROWNLEE DAM (Cont.)
DISSOLVED OXYGEN, mg/1
DATE
9/5/68
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Max.
3.7
3.8
4.5
4.9
4.3
3.8
5.2
4.9
4.9
4.7
5.4
5.5*
5.5*
5.0*
4.3
5.0
9.0
9.2
9.2
9.4
8.9
Min.
1.3
2.0
2.8
3.9
2.8
2.9
3.0
4.0
3.2
3.7
3.1*
4.1*
3.8*
3.5*
4.2
3.5
3.6
9.2
3.6
9.0
3.7
Ave.
3.2
3.2
3.3
4.3
3.3
3.6
3.2
4.0
4.2
4.2
- 4.2
4.3*
4.5*
3.8*
4.2
4.1
7.5
9.2
7.6
9.0
7.1
TEMPERATURE,
Max
21
22
22
22
21
22
21
21
22
21
21
No
No
No
22
22
22
22
22
22
22
Min.
19
19
21
21
20
21
20
21
21
20
20
Record
Record
Record
21
22
22
22
22
21
21
UC
Ave.
21
21
21
21
21
21
21
21
21
21
21
22
22
22
22
22
22
21
*Estimates
-------
TABLE.1
MONITORING DATA
BELOW BROWNLEE DAM (Cont. )
DISSOLVED OXYGEN, mg/1
DATE
9/26/68
27
28
29
30
10/1/68
10/2-17
Max
8.8
8.9
8.2
9.1
3.4
3.9
No
Min.
2.7
3.4
3.5
3.4
2.8
2.8
Record
Ave.
5.8
6.8
4.5
7.4
3.3
3.3
TEMPERATURE ,
Max.
22
20
20
20
20
19
No
Min.
20
20
19
19
18
19
Record
°C
Ave.
21
20
20
20
19
19
-------
TABLE 2
MONITORING DATA
BELOW OXBOW DAM
DISSOLVED OXYGEN, mg/1
DATE
8/6/68
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Max.
6.1
6.7
6.3
6.0
6.6
6.0
5.6
5.8
6.7
6.0
6.6
6.6
7.0
7.5
No record
8.8
9.3
9.3
9.3
9.2
9.7
Min.
5.1
5.0
5.0
5.0
5.3
4.8
5.0
4.9
5.0
5.0
5.8
5.8
5.0
6.3
8.5
8.5
9.2
8.5
8.8
8.5
Ave.
5.1
5.6
5.3
5.4
5.5
5.0
5.2
5.2
5.8
5.4
6.2
6.2
5.8
6.6
8.5
8.8
9.2
8.9
9.0
9.0
TEMPERATURE,
Max
21
22
22
22
22
22
22
22
22
22
22
22
22
22
No
21
21
21
21
21
21
Mln.
21
21
22
22
22
. 22
22
22
22
22
22
22
22
22
record
21
21
21
21
21
21
°C
Ave.
21
21
22
22
22
22
22
22
22
22
22
22
22
22
21
21
21
21
21
21
-------
TABLE 2
MONITORING DATA
BELOW OXBOW DAM (Cont.)
DATE
8/27/68
28
29
30
31
9/1/68
2
3
4
5
6
7
8
9-18
19
20
21
22
23
24
.25
DISSOLVED OXYGEN, mg/1
Max . Min . Ave .
8.5 6.6 7.6
8.8 7.6' 8.0
8.8 7.5 8.0
8.5 7.6 8.0
8.3 7.5 8.0
7.8 6.8 7.2
6.8 5.1 5.9
6.4 5.1 5.8
6.8 5.9 6.3
6.8 4.8 6.0
6.0 4.2 5.2
5.6 3.8 4.3
5.6 4.9 5.2
No Record
No Record
No Record
No Record
No Record
No Record
No Record
No Record
TEMPERATURE,
Max.
21
21
21
21
21
21
21
21
21
21
21
21
20
No
22
21
20
20
20
20
20
Min.
21
20
20
20
21
21
21
21
21
21
20
20
20
Record
21
20
20
19
20
19
20
°C
Ave.
21
21
21
21
21
21
21
21
21
21
20
20
20
21
21
20
20
20
20
20
-------
TABLE 2
MONITORING DATA
BELOW OXBOW DAM (Cont.)
DISSOLVED OXYGEN, mg/1
DATE
9/26/68
27
28
29
30
10/1/68
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Max. Min.
No Record
No Record
No Record
No Record
No Record
No Record
5.3 4.5
5.2 4.5
5.2 4.6
5.3 4.2
4.9 4.2
5.3 4.9
5.3 5.0
5.7 5.0
5.3 4.6
5.3 4.6
5.5 5.1
5.8 5.1
5.8 5.2
6.0 5.5
5.6 5.4
Ave.
4.7
4.7
4.6
4.6
4.5
4.9
5.1
5.0
5.0
4.8
5.2
5.2
5.4
5.5
5.6
TEMPERATURE
Max.
20
20
19
19
18
18
20
20
20
20
19
19
18
18
18
18
17
>~17
17
17
16
Min.
19
19
19
18
18
18
20
20
19
19
19
19
18
18
18
18
17
17
17
17
16
, °c
Ave.
20
19
19
18
18
18
20
20
20
19
19
19
18
18
. 18
. 18
17
1-7
. 17
17
.., 16
-------
TABLE 3
MONITORING DATA
BELOW HELLS CANYON DAM
DATE
7/24-8/22/68
8/23/68
24
25
26
27
28
29
30
31
9/1/68
2
3
4
5
6
7
8
9
10
11
DISSOLVED
OXYGEN, mg/1
Max. Min.
No Record
8.4
8.7
9.3
9.6
9.1
9.6
9.6
9.6
8.9
8.5
No Record
8.2
7.5
7.8
7.7
7.3
7.3
7.2
7.0
6.1
7.2
8.4
8.7
8.7
9.1
8.7
8.7
8.7
8.7
8.2
8.2
7.2
7.3
7.3
6.8
6.8
6.6
6.1
5.2
Ave.
7.9
8.6
9.0
9.2
9.1
9.2
9.2
9.2
8.7
8.4
8.2
7:2
7.5
7.4
7.1
7.0
6.7
6.5
5.8
TEMPERATURE ,
Max.
No
20
20
20
21
20
20
20
20
21
21
No
21
21
21
21
21
21
21
21
21
Min.
Record
20
20
20
20
20
20
20
20
20
20
Record
20
21
20
20
20
20
20
20
20
°C
Ave.
20
20
20
20
20
20
20
20
21
21
21
21
21
20
20
20
21
21
21
-------
TABLE 3
MONITORING DATA
BELOW HELLS CANYON DAM (Cont.)
DISSOLVED OXYGEN, mg/1
DATE
9/12/68
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
10/1/68
Max.
5.8
6.1
7.0
5.2
5.7
5.6*
5.4*
4.8
4.9
5.3
5.5
5.5
5.5
5.5
5.5
5.8
6.5
6.8
7.6
7.5
Min.
4.9
5.2
5.1
4.9
4.9
5.2*
5.0*
4.4
4.4
4.8
5.1
5.1
5.3
5.1
5.3
5.5
6.1
6.5
6.8
7.2
Ave.
5.2
5.4
5.4
5.0 ...
5.1
5.2*
5.2*
4.4
4.8
4.9
5.3
5.3
5.3
5.3
5.4
5.5
6.1
6.7
7.1
7.3
TEMPERATURE,
Max.
21
21
21
20
20
No
No
19
19
19
19
19
19
19
19
19
19
19
19
19
Min.
20
20
20
20
20
Record
Record
19
19
18
18
18
18
18
18
18
18
18
18
19
°C
Ave.
21
21
21
20
20
19
19
18
18
18
19
18
19
19
19
19
19
19
*Estimates
-------
TABLE 3
MONITORING DATA
BELOW HELLS CANYON DAM (Cont.)
DATE
10/2/68
3
4
10/5-16/68
DISSOLVED OXYGEN, mg/1
Max. Min. Ave.
7.5 6.8 6.8
No Record
No Record
No Record
TEMPERATURE,
Max.
17
16
16
No
Min.
16
16
15
Record
°C
Ave.
17
16
16
------- |