WATER QUALITY STUDY: MIDDLE SNAKE RIVER FEDERAL WATER POLLUTION CONTROL ADMINISTRATION NORTHWEST REGION PORTLAND,OREGON ------- 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 ------- 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 ------- 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 ------- 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 ------- 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. ------- 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. ------- O 'O JO JO 40 SO FIGURE 1 Middle Snake River Study Area ------- 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. ------- 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. ------- 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. ------- 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. ------- 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. ------- 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 ------- 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 ------- 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 ------- 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. ------- 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) ------- 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). ------- 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, - = ------- 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 ------- 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. ------- 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 ------- 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 ------- 23 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. ------- 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. ------- 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. ------- 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. ------- 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 ------- 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 ------- 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 ------- |