Mgt-Graban1964 Evaluation of Fish Facilities at Brownlee and Oxbow Dams

Home , Brownlee Dam, Oxbow Dam

STATE OF IDAHO

FISH AND GAME DEPARTMENT John

R. Woodworth, Director

EVALUATION OF FISH FACILITIES

BROWNLEE AND OXBOW DAMS

James R. Graban Fishery Biologist

May, 1964

EVALUATION OF FISH FACILITIES AT BROWNLEE AND OXBOW DAMS

INTRODUCTION

On August 4, 1955, the Idaho Power Company was licensed, through Federal Power Commission Project 1971, to construct a three-dam complex, consisting of Brownlee, Oxbow, and Hells Canyon hydroelectric dams on the middle Snake River.

On November 17, 1960, the F.P.C. issued an order to Idaho Power Company to consult and cooperate with the Department of Interior and the fisheries agencies of the States of Idaho, Oregon, and Washington, to determine a mutually-satisfactory program for the purpose of testing and evaluating the fish facilities at the Brownlee and Oxbow projects. The costs of which program shall be born by the licensee.

In February, 1961, the Idaho Fish and Game Department signed an agreement with Idaho Power Company to begin the fish facility evaluation study at Brownlee and Oxbow Dams on the Middle Snake River. The evaluation study was conducted under the general supervision of a steering committee, consisting of representatives of the fish and game agencies of the States of Idaho, Oregon, and Washington, the Idaho Power Company, and the Department of Interior. Field supervision was provided by the Idaho Fish and Game Department. The study spanned a period of three years and is concerned with evaluating the upstream and downstream facilities for passing migratory game fish past the two dams, to determine if the fish-passage facilities function at designed, and to recommend changes in fish passage conditions or request other passage facilities. Figure 1 shows the relative locations of Brownlee and Oxbow Dams.

Brownlee Dam, the larger of the two completed hydroelectric projects, was completed in 1958 (Figure 2). Oxbow Dam, located about 12 miles downstream from Brownlee Dam, was completed in 1961 (Figure 3).

DESCRIPTION OF PROJECTS AND PERMANENT FISH

Brownlee Dam

Brownlee Dam is a rock-fill, clay-core structure which creates a gross head of 277 feet and has a crest width of 1,320 feet. Brownlee is a high head dam with a storage reservoir approximately 58 miles long, which undergoes a maximum fluctuation of 101 feet in surface levels. Usable storage capacity is 1,000,000 acre feet, The primary function of the project is power generation at a powerhouse on the Idaho shore. A single spillway is located on the Oregon shore. Additional regulation of the forebay is provided by flood ports; otherwise, all discharge from the project is through the turbines draft tubes. Power is produced with Francis-type turbines. The U. S. Army Corps of Engineers requires Brownlee Reservoir to be drawn down at least 43 feet by March 1 of each year for flood control.

A barrier net facility for collecting downstream migrant fish is located in the impoundment approximately one mile upstream from the dam(Figure 4). There is no upstream fish passage facility at Brownlee Dam because adults collected at Oxbow Dam are truck-transported past both structures.

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Oxbow Dam

Oxbow Dam consists of a rock-fill, clay core-dike, having a gross head of 117 feet and a crest width of 945 feet. Oxbow Dam, completed in 1961, is a river-run type project with a relatively low head and small impoundment, The reservoir has a usable storage capacity of 5,500 acre feet and extends 12 miles upstream to the base of Brownlee Dam. The dam has two spillways, a fuse plug structure for emergency use on the Idaho shore and conventional concrete structure on the Oregon shore. With the exception of flows released to maintain fish attraction to the upstream fish facility at the base of the dam or spillway releases, all discharge from the reservoir is through Francis-type turbines.

Oxbow Dam is located at the upstream end of a large "oxbow" with a power plant positioned at the lower end, a distance of 2.5 miles (Figure 3). Two conduits, which penetrate a rock promontory forming the inside shore of the "oxbow", carry water to the power plant. It is thus necessary for upstream migrating salmon and steelhead to pass through the influence of the powerhouse tailrace and adjust to the much smaller volume of flaw around the "oxbow" provided to attract fish to the upstream migrant fish facility at the base of Oxbow Dam on the Oregon shore spillway.

EVALUATION OF UPSTREAM MIGRANT FISH FACILITIES

Description of Upstream Facilities

The upstream fish facilities at Oxbow consist of a short fishway section to attract and collect upstream migrants and a trap to hold and transfer fish to transport trucks for hauling around the dams. The facility is similar to a prototype on the White River near Buckley, Washington. A similar facility is also used on a part-time basis for passing upstream migrants at Pelton Dam on the Deschutes River, Oregon, and North Fork Dam on the Clackamas River.

Fish enter the short fishway section (Figure 5), swim over a finger-weir into a holding pool, and continue through a louvred V-entrance into a brail compartment with a sloping floor which, when raised, forces them over a white counting board into a hopper. The water-filled hopper is moved mechanically inside a superstructure to a position over a water-filled fish transport truck. The hopper is lowered until the hopper probe is inserted and sealed into a hatch atop the fish truck. Fish are gradually transferred within a water column from hopper to fish truck by a control valve at the hopper base while water is simultaneously discharged from the truck tank.

Evaluation of Upstream Migrant Collection at the Oxbow Dam Trap

The Oxbow spillway fish trap is located on the upstream side of the "oxbow" while the outlet of the Oxbow Dam powerhouse is located on the downstream side (Figure 3). In the spring of 1961, the Oxbow pool was being filled and no water was released through the Oxbow powerhouse until late May. The only water discharged from Oxbow Dam was bypassed around the "oxbow," Thus, in May, 1961, fish migrating upstream were not subjected to the influence of the Oxbow tailrace discharge as were those in May of 1962 when the powerhouse was in operation.

On May 11 and 12, 1961, 17 chinook salmon and four steelhead trout were taken from the Oxbow spillway trap, tagged, transferred to tank truck, and released downstream in the Snake River near Homestead, Oregon, a distance of five miles. On May 3 and 10, 1962, 15 chinook salmon and 14 steelhead were taken from the trap, tagged, and released downstream in the same area as the 1961 release. The number and rate at which these fish returned to the Oxbow spillway trap is shown in Table 1.

A second experiment was conducted to determine if a flow of 1,000 c.f.s. was necessary to attract fish round the "oxbow" to the spillway trap.

At the beginning project operations, Idaho Power Company was required under Federal Power Commission order to maintain a continuous flow of 1,000 c.f.s. around the "oxbow" to attract upstream migrating fish to the spillway fish trap. An experiment was conducted to determine if such a flow was necessary to attract fish around the "oxbow" to the spillway trap. This study was a cooperative effort by the Idaho Power Company, the Federal government, and interested states under the approval of the Federal Power Commission,

The relationship of water flows around the bow to fish counts for 1962 is shown in Figure 6. There appears to be no consistent relationship between changes in flow and fish movement, On October 1, 1962, the salmon and steelhead count was 120 fish and on the following day, with the flow reduced from 650 c.f.s. to 250 c.f.s., the count rose to 245 fish, Other high and low counts appear at random and apparently are independent of the flows tested around the bow.

Nongame Fish Separating Device

Large numbers of river-run, nongame fish have been taken with the adult salmon and steelhead at the Oxbow upstream trapping facility since operations began. This condition has tended to interfere with the efficiency of the trapping and hauling operation and occasionally has resulted in mortality to salmon and steelhead from smothering. Concentration of game with nongame species also may contribute to the transmission of disease. An investigation was made of possible ways to separate the salmon and steelhead from the other fish in the trap. For this purpose, varied combinations of experimental, perforated wooden plates were installed between the hopper and the brail sections of the trap. A plate with 2 1/2-inch diameter perforations_ proved to be the most effective in removing smaller nongame fish from the brail compartment (Figure 7), Adjustment of hole dimension may be necessary from year to year because of changes in fish size. With the plate in operating position, the smaller trash fish first enter the hopper through the perforation and the larger salmon and steelhead remain in the brail for later transfer to the transport truck without serious complication from the undesirable species. Although all of the trash fish are not separated from the salmon and steelhead by the use of this plate, large numbers are eliminated. On occasion, some resident game fish and small steelhead have moved through the plate. Because of this problem, the plate may not be used during the fall steelhead season when lesser numbers of undesirable fish are present. The separating device appears to function adequately.

Evaluation of Release Sites for Upstream Migrants

Upstream migrants collected at the Oxbow Dam fish traps were hauled by tank truck around Oxbow and Brownlee Dams and released in Brownlee Reservoir two miles above the dam and in the Snake River upstream from the reservoir, a distance of 80 miles from the point of collection.

A study was conducted in 1961 to determine the relative numbers of fish released at each site, which subsequently were recovered on the spawning grounds. -8-

Fish released in the Brownlee Reservoir were hauled for a relatively short distance (14 miles) but were required to swim through approximately 50 miles of reservoir to reach the spawning grounds some 100 to 125 miles upstream from the release site, Fish released in the Snake River (five miles upstream from Weiser, Idaho) were transported in the tank truck 77 miles, approximately three hours longer than fish released in the reservoir, but they were not required to swim through the reservoir,

Fish were transported to the release sites in tank trucks. Each truck tank had a 1,000-gallon capacity and was equipped with aerators, recirculating pumps, and an auxiliary oxygen supply system. To cool the water, an ice compartment with a 500-pound capacity is located in the anterior portion of each tank (Figure 8). From 25 to 30 salmon and/or steelhead were transported in each truck load to a holding site for tagging before release. The fish hauled to Weiser were in as good condition as those delivered to Brownlee release site.

At the release site, salmon were transferred from truck to a 3 by 4 by 10-foot holding pen for tagging, These pens were canvas-covered to quiet the fish and were lined with saran net to protect fish from injury and suffocation. Fish were dipnetted into the anesthetizing tank, a 2 by 2 by 4-foot stock-watering tank, also covered with canvas, and then tagged. Sandoz M. S. 222 was used to anesthetize the fish.

At the time the first fish were tagged, water temperatures were about 70° F. and a dosage of 80 p.p.m. of anesthetic was sufficient but, as the water cooled, dosage was increased progressively until 160 p.p.m. was required at the Weiser release site when water temperature reached approximately 50° F. About two minutes were required to immobilize fish for tagging. Tags were attached to the fish through the flesh of the back below the insertion of the two posterior rays of the dorsal fin.

Fish were held in the pen only long enough to complete the entire tagging operation--not more than 30 minutes. Approximately 30 percent of the 4,646 fall chinook salmon transported around Oxbow and Brownlee Dams was tagged with red, 17/32-inch diameter, numbered Peterson disc tags. Almost equal numbers were tagged and released at the Brownlee Reservoir and Weiser sites.

To recover tags, spawning ground surveys were conducted periodically from November 1, 1961 to January 18, 1962. The spawning area extends from Swan Falls Dam downstream for a distance of about 25 miles and was divided into four sampling sections ( Figure 9). The lower three sections, where 90 percent of the spawning occurs, were surveyed once each week—Section 2 on Monday, Section 3 on Wednesday, and Section 4 on Friday--weather and water conditions permitting. Section 1, located immediately below Swan Falls Dam, was surveyed when time permitted. Each fish carcass recovered during the surveys was measured, examined for sex, degree of spawning, presence or absence of tag, and each was marked for recognition (to prevent duplication of data) during subsequent surveys.

Of 686 fish tagged and released in Brownlee Reservoir, 83 were recovered on the spawning grounds (Table 2). Seventy were recovered in ground surveys, seven by anglers, and six by miscellaneous means.

Of the 688 salmon tagged and released at Weiser, 98 were recovered on the spawning grounds (Table 3). Eighty-three were recovered in ground surveys, ten by anglers, and five were miscellaneous recoveries. A summary of the number of fish tagged, percent recovered, and temperatures of the river and transportation water at each release site appears in Tables 2 and 3. -12-

Statistically, there was no significant difference in recovery rates between marked fish released in the reservoir and those released in the Snake River above the reservoir.

The recovery rates for tagged and untagged fish released into Brownlee Reservoir indicate that tagging mortality occurred. Of 3,272 untagged salmon released in the reservoir, 14.3 percent were recovered on spawning grounds, Of the 686 tagged salmon released in the reservoir, 10.2 percent were recovered on the spawning grounds. The difference between these two recovery rates is statistically significant. During this experiment, the tagging mortality appeared to approach 30 percent.

Columnaris in the Middle Snake River

In conjunction with the 1961 fall chinook tagging program, Dr. E. J. Ordal, pathologist from the University of Washington, was commissioned by Idaho Power Company to conduct a study on the incidence of C, columnaris in adult fall chinook salmon. In his report Dr. Ordal states that over 25 percent of the adult chinook salmon and steelhead trout examined at tag release sites were infected with C. columnaris. It was found that the water in the fish transports contained 1,200 to 3,000 cells of C. columnaris per milliliter, or about 4, 8000000 to 12,000,000 per gallon of the water circulating within the fish transports.

Gills of a number of migrating adult salmon and steelhead were examined for C. columnaris lesions. Whether or not the fish examined had columnaris lesions on the gill s was recorded along with the tag number. During the spawning ground surveys in the fall of 1961, an attempt was to be made to determine the significance of the presence of C. columnaris on the ability of adult migrating salmon to reach the spawning ground and su cessfully spawn. This was to be accomplished by correlating observations by Dr. Ordal and records of the fish checked, tagged and released at the aforementioned tagging sites with these same fish and others recovered on the spawning grounds.

Unfortunately, it was discovered during the spawning ground surveys that it was very difficult to determine whether or not gill deterioration on the dead fish resulted from disease or natural decomposition. Many fish which spawned successfully exhibited gill deterioration which could have resulted from C. columnaris infection. Therefore, no valid conclusions could be made from the recovery of spawned-out carcasses.

Report on Columnaris Study-Middle Snake River 1961, E. J. Ordal, Seattle, Washington.

-17- EVALUATION OF DOWNSTREAM MIGRANT FISH FACILITY

Studies made at the downstream migrant fish facilities were concerned primarily with the success of collecting fish at the barrier net. Studies were conducted to determine (1) if significant numbers of fish were bypassing the net, (2) the efficiency of the pumping system, and (3) the effectiveness of the collection barges to attract and collect downstream migrants.

Description of Downstream Migrant Facilities

The Brownlee net barrier is located approximately one mile upstream from Brownlee Dam. A curtain-like network of horizontal and vertical cables suspended from a series of pontoons at the forebay surface comprises the nets framework. A wire-mesh backing, which in turn supports the net, consisting of panels of 8-mesh-per-inch saran webbing net, is attached to the network of cables. A main cable at the bottom of the net bears the strain from the smaller horizontal and vertical cables.

In plain view pontoons and net extend across the forebay in the form of an expanded "U" with the apex downstream (Figure 10). The gap from each end of the net to the shore is spanned by wing-nets of saran. The barrier net is one-half mile in length by 140 feet in depth. However, since the bottom portion of the net extends slightly upstream to assume a more or less horizontal plane to lead migrants upward and prevent their sounding, the effective depth is designed to be approximately 120 feet. The net is maintained in this position by a series of buoys which attach to and partially support the weight of the main cables. The entire facility can be adjusted at its shore attachments to accommodate fluctuations in forebay level.

Downstream migrants are collected at the surface in three artificial outlets or " °skimmers,° one at each end and one at the center of the net. These skimmers are designed with tapered-Inclined entrance flumes with intake openings 14 feet by 14 feet (Figure 11). Inflow velocity is increased gradually by pump evacuation to attract the fish. Fish must enter the skimmer via the entrance flume, swim In increasing velocities toward a restricted point in the flume channel where flow velocity approaches eight feet per second, and into a compartment where most of the water is withdrawn through revolving screens by pumps. Fish then pass over an inclined screen through which the remaining water is withdrawn. Fish drop onto a sorter for separation by size into three compartments, two brail compartments for salmon and steelhead and a separate compartment for large rough fish and debris.

Fish are transferred from the skimmer barges to shore-loading facility via a pumping system. The operator can withdraw the contents of any skimmer brail compartment through flexible submerged pipelines to a sub-surface fish-lock in the main line by control of valves (Figure 12). The lock, an expanded section of the main line, functions to reduce water velocity. The lock is screened to prevent fish from entering the pump. Reversal of the pump conveys fish through the main line to the shore-loading facility, (Figure 13), where an inclined screen separates them from the transportation water. Fish may be loaded directly into a waiting tank truck or into a holding tank, (Figure 14), where they can be anesthetized, counted, identified, measured, and examined for marks and injuries. The revived fish are placed in tank trucks for hauling to the release site below Oxbow Dam powerhouse.

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Underwater Television Observations

One experiment, using underwater television cameras to determine the condition of the barrier net was conducted by Idaho Power Company in 1961. The uses of television was explored as a possibility of doing without SCUBA divers to make routine examinations of the net at greater depths. The month of January was selected because of clear water conditions in Brownlee Reservoir, The results of the experiment were unsuccessful because the field (of the camara lens) of observation, to make the method practical, was limited to too small of an area.

Effectiveness of the Barrier Net

Tests were conducted in 1963 to obtain some measure of the effectiveness of the barrier net in preventing fish from reaching the dam and leaving the reservoir through the turbines or over the spillway. To accomplish this, test releases of fingerling fish were made in various locations on both the upstream and downstream sides of the net,

Hatchery-reared fingerlings from Snake River fall chinook eggs were used in most of the experiments. The fish were anesthetized, marked, transported to Brownlee Reservoir, and held for 24 hours prior to release. Wild Snake River fall chinook fingerlings were captured, marked, and released simultaneously with three groups of hatchery fish to determine behavior differences, if any, between the two groups of fish. A fifteen-foot nylon seine was used to capture wild fall chinook smolts in the spawning area, with limited success. Wild fish captured by Bureau of Commercial Fisheries migrant dippers, located in the Snake River downstream from Weiser, were used also, Fingerlings from Oxbow hatching channel were not used as these fish were considered too small to handle and mark without injury.

Test releases were programmed to coincide with actual conditions wild fish were subjected to during the period of the fall chinook downstream migration in the months of April and May. A total of 18 releases were made. Nine test groups of 1,200 to 3,000 fingerling chinook were released 300 feet upstream from the net and nine similar releases were made 300 feet downstream from the net. Fish were transferred from live boxes submerged in the forebay to a boat equipped with a 2- by 2- by 4-foot, oxygen- equipped, stock-watering tank. Fish were dip-netted and released at random approximately 300 feet from the upstream and down-stream faces of the net.

In all but two tests in which fish were released downstream from the net, one or more fish from each lot was recovered at the shore-loading facility (Table 4l. Conversely, from all but one test lot of fish released upstream from the net, one to 85 fish were captured in the scoop traps downstream from Brownlee Dam. Results of the tests indicate that fish were able to move through or beneath the barrier net,

Barrier Net Collection Barges

The effectiveness of the barrier net collection barges to attract and collect downstream migrant salmon and steelhead were tested over a three-year period (1961 through 1963). The collection barges were designed to create a continuous flow of 100 c.f.s. under perfect and ideal operating conditions; i.e., barges were in proper trim and the inclined and reversible screens were perfectly clear of trash and debris. Since ideal operating conditions rarely existed, the effect of trash and debris on the total designed flow through individual collection barges is unknown. -24-

Hatchery-reared fall chinook fingerlings were processed in the same manner as test fish utilized in testing the effectiveness of the barrier net system to attract and collect downstream migrant salmon. Two tests were made of the ability of the entrance flume to attract and transport fish to the brail compartments in the skimmer barges (Figure 11). One thousand hatchery-reared fall chinook were released midway in the entrance flume of Number 3 barge (Idaho side). Percent of recovery ranged from 32 with one pump in operation to 49 with two pumps in operation (Table 5).

In 1962 and 1963, twelve test lots of marked, hatchery-reared fall chinook salmon and two test lots of wild fall chinook salmon were released approximately 50 to 300 feet across the upstream face of the barrier net. Recovery rates at the shore collection facility ranged from 0.7 to 14.8 percent. There was no noticeable difference in behavior between wild and hatchery-reared fall chinook fingerlings. Test results indicate that these fish find and enter the artificial outlets fortuitously, i. e,,, the artificial currents at the skimmer barges provide little or no attraction to the downstream migrants. In tests performed in 1963 (considered most reliable of all those performed), of 21,152 marked fish released upstream from the barrier net, only 1,239 were recovered at the shore loading facility, an average return of five percent. Recovery rates at the barrier net of wild fish caught, marked, (in 1962) and released at Weiser ranged from 0.8 to 10 percent (Table 10). Results of initial tests in 1961 are questionable because of undesirable water temperatures and small numbers of fish released.

Efficiency of the Barrier Net Pumping System

Six tests were made in 1961 and 1962 to determine the efficiency of the barrier net pumping system to transfer fish from the skimmer barges to the shore loading facility. Hatchery rainbow trout approximately the size of the salmon smolts were used in the 1961 tests. Hatchery-reared Snake River fall chinook salmon were used in the 1962 tests. Recovery of marked salmon ranged from 74 to 100 percent and averaged 90 percent for the six tests (Table 6).

If the skimmer barges are maintained in fish-tight condition, pump systems kept relatively free of trash and debris, and all valve transfer systems are functioning properly, a recovery rate in excess of 95 percent can be expected. This system appears to function satisfactorily, Fate of unrecovered fish is unknown and no attempt was made to determine fish mortality within the barrier net system.

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The Number of Migrants Collected

Juvenile chinook salmon and steelhead trout have been collected at the Brownlee barrier net since 1959. The number of migrant salmon collected at the net has declined from 130,551 in 1959 to 13,482 in 1963 (Table 7), The number of steelhead captured has declined from 18,250 in 1959 to 1,212 in 1963.

The reduction in number of downstream migrant salmon is possibly due in part to decreased numbers of spawners. However, the evidence presented in Table 8 indicates that major reductions in the number of downstream migrants collected at the barrier net took place before any major reduction in the number of spawners occurred. The number of female fall chinook and spring chinook (both sexes) spawners ranged from 4,000 to 5,000 fish from 1957 to 1961. Most of the chinook juveniles appeared to move through the reservoir during the two years after emergence. Thus, offspring from the relatively good escapement of females in 1961 would have been caught at the barrier net in 1962 and 1963. In both of the latter years, the smallest numbers of migrants were collected at the barrier net.

A major reduction in number of downstream migrant steelhead collected at the barrier net also occurred before a reduction in the number of spawners. The relatively good steelhead spawning escapements of 1957, 1958, and 1959 spawned in 1958, 1959, and 1960, respectively, and produced juveniles that would have migrated through the reservoir as two-year-old fish in 1960, 1961, and 1962. The number of juvenile steelhead collected at the barrier net in these latter years was at the low level of 2,000 fish or less.

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Scoop Trap Catches Below Brownlee Dam

In addition to those fish collected at the barrier net, there is an unknown number of fish which pass under or through holes in the barrier net and leave the reservoir through the spillway or turbines. During 1963, six large scoop traps were fished in the tailrace and river downstream from Brownlee Dam, During the same period that most of the fish were caught at the barrier net, 2,477 chinook salmon and 130 steelhead trout were caught in the scoop traps (Table 9).

Two periods of rather large catches of downstream chinook migrants occurred during 1963 in the downstream migrant traps below Brownlee Dam. The first period of high catches occurred between January 23 and March 1 and the second period during the months of June and July.

A possible explanation for the movement of fish, which either passed through or under the barrier net, between January 23 and March 1, was the gradual drawdown of the reservoir from full pool elevation of 2,077 feet to 2,049 feet, a reduction of 25 feet in the reservoir storage level. This, coupled with a relatively high powerhouse discharge, apparently increased velocities in the reservoir, causing salmon and steelhead to leave the reservoir. On some days the scoop trap catches exceeded the barrier net facility catches (Figure 15), Unfortunately, no measure of escapement past the dam is available prior to January 23.

Beginning February 4, and ending February 11, large quantities of water were spilled at Brownlee, ranging from 2,100 c.f.s. to 12,800 c.f,s. plus daily powerhouse discharges. Except for the second day of the spill period, no appreciable change was noted in the catches at the barrier net or scoop traps below the dam.

Three days after termination of spill discharge, large catches of downstream migrants occurred. This may have been influenced by the short duration of spill, or, more likely, by the arrival of turbid waters from upriver spring floods.

Catches at the barrier net declined with a decrease in the reservoir turbidity (Figure 16). Turbidity was determined by sechi disc readings.

Throughout the entire downstream trapping period, the catches at the scoop traps appeared to increase as the barrier net catches increased, and conversely when the barrier net catches decreased, the scoop trap catches appeared to decrease also (Figure 15).

The second period of high catches in 1963, occurred during the month of June and the last two weeks in July. Large amounts of water were released past the dam through June and the first two days in July. Since there were no scoop traps fishing the tailrace during this period, it is not possible to determine whether or not the majority of the fish caught in the scoop traps at the bridge came over the spill or through the turbines.

An experiment designed to test whether or not downstream migrants could be flushed through the reservoir via the spillway during warmer water temperatures and large water releases was conducted. Coupled with the large water releases at Brownlee, large sections of the barrier net were removed at the suggestion of the members of the Columbia Basin Fisheries Technical Committee. Idaho Power Company SCUBA divers began this task on June 24. Beginning 20 feet -32-

below the water surface portions of the net were opened to a depth of 40 feet at random intervals until an approximate area of 1,500 feet was opened across the net.

During the test period, there was no appreciable increase in the scoop trap catches. It is interesting to note, however, that catches at the barrier net during the first four days the net was open increased more than 200 percent over the catches of the preceding weeks in the month of June.

During the period of spill, water velocity at the bridge scoop trap sites ranged from 5.28 to 8.61 feet per second. The scoop traps fished more efficiently during this period than during periods of no spill when the velocities were less than optimum.

Computation of an estimate of the total number of fish bypassing the net based on scoop trap catches does not appear practical because (1) the distribution of downstream migrants in the river is probably not uniform and (2) fish are able to move in and out of the scoop traps. Escapement of fish placed in scoop traps fishing the river ranged from 3 to 100 percent.

A large percentage of the fish collected in scoop traps below the dam were dead (Table 9). Tests were conducted to determine the extent of mortality caused by the trapping operation. Mortalities up to 100 percent occurred to live fish placed for up to 20 hours in traps located in the tailrace. This high mortality was caused by turbulence. Baffle boards placed in holding compartments of the traps reduced the mortality in tailrace traps. Mortality ranged from zero to four percent of live fish placed for up to 20 hours in traps fishing the river following this improvement. Many of the dead fish examined in the tailrace traps showed some evidence of subjection to pressure changes- -bulging eyes, broken air bladder, bleeding at the gills, mouth and anus, or protrusion of viscera through the body wall and anus, Some mechanical injuries were observed, such as beheaded fish, abrasions, and bodies severed at various places. Evidence of pressure change and mechanical injury were observed mostly in chinook and steelhead 150 millimeters or more in length.

During 1962, large numbers of juvenile salmon and steelhead were captured and marked before they entered Brownlee Reservoir in order to (1) determine with assurance the origin and age of fish collected at the barrier net, and (2) to obtain an estimate of the escapement of fall chinook into the reservoir. Salmon and steelhead were collected for marking from the Snake River near Weiser, Idaho, by the use of the barge-type scoop traps (Fig. 17). The number of fish marked and recaptured is presented in Table 10.

From the mark and recovery program, it was determined that spring chinook appear to migrate through the reservoir more readily than either fall chinook or steelhead trout. More than 90 percent of the 1960 year class spring chinook recovered at the barrier net were taken during the spring that the fish were Age Class I fish, their normal, migration age (Table 10). It appears that 90 percent of the spring chinook smolts which leave the reservoir do so as Age Class I fish, Although a higher percentage of the marked spring chinook were recovered than either fall chinook or steelhead, the escapement of spring chinook through the reservoir ( approximately 6 to 11 percent, plus those fish that survive passage through or over the dam) does not appear to be adequate to maintain the run, The 1959 year class of spring chinook was at first subjected to the full influence of the Brownlee-Oxbow projects; i.e., both adult and downstream migrants were subjected to the environment of Brownlee Reservoir. Four-year cycle offspring from the 1959 year class returned in 1963 and this run was the lowest count of fish on record at Oxbow Dam. -36-

Marked fall chinook of the 1961 year class were recaptured at the barrier net in 1962 and 1963. Based on the number of recaptures, it appears that only a small fraction of the fall chinook pass through the reservoir during the first year of their life, their normal migration age (Table 10),

Samples of marked and unmarked fish were measured in 1962 and 1963 in order to facilitate identification of the various races and age classes of fish collected at the barrier net, The Age Class 1 spring chinook and Age Class 0 fall chinook had rather distinctive length frequency distributions during the spring months (Figure 18). Age Class 1 fall chinook and Age Class II spring chinook ( residuals) had overlapping length frequency distributions. The catches of chinook salmon at the barrier net in 1962 and 1963 were divided into various races and ages ( Table 11) on the basis of length frequency distributions and tag recoveries (see Appendix A).

Estimates of the escapement of 1961 year class fall chinook into Brownlee Reservoir were computed from the tag and recovery data available. The general formula is:

In 1962, approximately 1,645 fall chinook of the 1961 year class were never recaptured at the barrier net, Thirty-three of these fish were marked. The estimate of recruitment to the reservoir using this data was 791,644 fish. The influence of marking mortality on these data is unknown.

In 1963, approximately 3,000 additional fall chinook of the 1961 year class were recaptured, including 102 marked fish. The estimated recruitment based on recaptures from both 1962 and 1963 was 546,420 fish,

Either of these estimates of recruitment to the reservoir seem reasonable when compared to the number of migrants that would be expected from the potential egg deposition in 1961. It is estimated that there were 3,000 female fall chinook released upstream to spawn naturally in 1961. At an average egg content of 4,000 eggs per female, these spawners would have had a potential egg deposition of 12 million eggs. The recruitment estimate of 546,420 fish represents a survival rate of 4.6 percent from egg to migrant fry stage; a survival rate similar to that found in studies designed to determine survival.

Using the estimated escapement to the reservoir of 546,420 fish, it would appear that a small percent of the fall chinook ultimately pass through the reservoir. The barrier net catch of 1961 year class fall chinook was approximately 5,000 fish. -39-

SUMMARY

On August 4, 1955, the Idaho Power Company was licensed, through Federal Power Commission Project 1971, to construct a three-dam complex, consisting of Brownlee, Oxbow, and Hells Canyon hydroelectric dams on the middle Snake River. This study is concerned with Brownlee and Oxbow projects only.

On November 17, 1960, the F.P.C. issued an order to Idaho Power Company to consult and cooperate with the, Department of Interior and the fisheries agencies of Idaho,Oregon, and Washington, in determining a mutually satisfactory program for the purpose of testing and evaluating the fish facilities at Brownlee and Oxbow projects.

In February, 1961, the Idaho Fish and Game Department signed an agreement with Idaho Power Company to evaluate the upstream and downstream fish facilities for passing migratory game fish past the two dams, to determine if the fish passage facilities functioned as designed, and to recommend changes in fish passage conditions or request other passage facilities.

Brownlee Dam, the larger of the two completed hydroelectric projects, was the first to be constructed. Brownlee is a high head, rock-fill dam with a reservoir 58 miles long with a usable storage capacity of 1,000,000 acre feet. The primary function of the project is power production. All water discharge passes through Francis-type turbines. Additional regulation of the forebay is provided by flood ports. The U. S. Army Corps of Engineers requires Brownlee Reservoir to be drawn down at least 43 feet by March 1 of each year for flood control.

A barrier net facility for collecting downstream migrant fish is located in the Brownlee impoundment approximately one mile upstream from the dam.

Oxbow Dam is a rock-fill, clay core dike that creates a reservoir with a usable storage capacity of 5,500 acre feet and extends 12 miles upstream to the base of Brownlee Dam. With the exception of flows released to attract fish to the upstream fish facility at the base of the dam, or spillway releases, all discharge from the reservoir is through Francis-type turbines. Because of the unique location of the powerhouse in relation to the upstream fish facility, it is necessary for upstream migrating salmon and steelhead to pass through the influence of the powerhouse tailrace and continue upstream in the much smaller volume of flow around the "oxbow" to the spillway fish trap at the base of the dam.

The upstream fish facilities at Oxbow consist of a short fishway section where fish are captured in a modified Buckley Trap. The fish are transferred from the trap to a tank truck, hauled above the two dams, and released in Brownlee Reservoir to continue their migration upstream.

Experiments were conducted to determine the effects on upstream migrant collection at the Oxbow Dam spillway fish trap of (1) water flows from the Oxbow powerhouse and (2) the volume of water flow around the "oxbow." In May, 1961 and 1962, a total of 32 chinook and 18 steelhead were taken from the Oxbow trap, tagged, and relased downstream from the dam. The number and rate at which these fish returned to the Oxbow spillway trap were recorded. The number of days until recapture at the Oxbow trap ranged from 2 to 32, days. Fish subjected to the influence of powerhouse flows did not appear to be affected in their return to the Oxbow trap. This conclusion is based on the assumption -42- that the tagged fish behaved in a manner similar to untagged fish.

An experiment was conducted to determine if a flow of 1,000 c.f.s. was necessary to attract fish around the "oxbow" to the spillway trap. There was no consistent relationship between flows around the oxbow and the number of fish that reached the spillway trap.

Results of this study indicate that a flow of 1,000 c.f.s. around the "oxbow" is not necessary to attract fish to the Oxbow Dam spillway fish trap. Upon these results, Idaho Power Company requested that an interim order be issued by the Federal Power Commission to change the water releases at the Oxbow development to meet minimum requirements for satisfactory spring and fall migration of salmon and steelhead as determined by the study. Since the fishery agencies and other interested parties interposed no objection to the licensees request, the Commission ordered the following water releases at the Oxbow spillway and spillway fish trap: (a) From November 1 through March 15 of each year, a minimum flow of 250 c.f.s (b) From March 16 through June 30 of each year, a minimum flow of 500 c.f.s (c) From July 1 through August 31 of each year, a minimum flow of 250 c.f.s and (d) From September 1 through October 31 of each year, a minimum flow of 750 c.f.s.

An investigation was made of possible ways to separate salmon and steelhead from nongame species in the Oxbow spillway trap. A wooden plate with 2 1/2-inch diameter perforations proved to be the most effective in removing smaller nongame fish from the brail compartment. Adjustment of the hole dimension may be necessary from year to year because of changes in fish size.

A tagging study was conducted in the fall of 1961 to determine whether the upstream migrant salmon should be released in the Snake River above Brownlee Reservoir or into the reservoir immediately upstream from the dam. The spawning ground recovery of reservoir-released fish was not significantly different from the recovery of fish released in the river upstream from the reservoir.

In conjunction with the 1961 fall chinook tagging program, Dr. 8. J. Ordal, pathologist from the University of Washington, conducted a study on the incidence of C. columnaris in adult fall chinook salmon. He reported that over one-fourth of The adult chinook salmon and steelhead examined at the Weiser and Brownlee release sites were infected with columnaris disease. It was discovered during the spawning ground surveys that it was very difficult to determine whether or not gill deterioration on dead fish resulted from disease or natural decomposition. Studies at the downstream migrant fish facilities were conducted to determine (1) if significant numbers of fish were bypassing the net; (2) the efficiency of the pumping system; and (3) the effectiveness of the collection barges to attract and collect downstream migrants.

Hatchery-reared fingerlings from Snake River fall chinook eggs, plus wild Snake River fall chinook fingerlings, were used in test releases to obtain some measure of the effectiveness of the barrier net in preventing fish from reaching the dam and leaving the reservoir through the turbines or over the spillway. Nine test groups of 1,200 to 3,000 chinook were released 300 feet upstream from the net and nine similar releases were made 300 feet downstream from the net.

In all but two tests in which fish were released downstream from the nets one or more fish from each lot was recovered at the shore-loading facility. Conversely, from all but one test lot of fish released upstream from the net, one to 85 fish were captured in scoop traps downstream from Brownlee Dam.

Results of tests designed to measure the effectiveness of the barrier net indicate that fish were able to move through or beneath the net. It is believed that, from. the beginning, the barrier net never constituted a complete barrier. -43- Even after the wing nets were installed on both the Idaho and Oregon sides, the net was never completely fish-tight. Despite a constant effort by the Company diverse it was an almost insurmountable task to maintain the nearly seven acres of submerged netting in a fish-tight condition.

It is likely that fish passed through holes in the net and, also, with favorable temperature and oxygen conditions, passed beneath it.

The effectiveness of the barrier net collection barges to attract and collect downstream migrant salmon and steelhead was tested over a three-year period (1961- 1963).

Two tests were made of the ability of the entrance flume to attract and transport fish to the brail compartment in the skimmer barges, Percent of recovery ranged from 32 with one pump in operation to 49 with two pumps in operation.

In 1962 and 1963, twelve test lots of marked hatchery-reared fall chinook salmon and two test lots of wild fall chinook salmon were released approximately 50-300 feet across the upstream face of the barrier net, Recovery rates at the shore collection facility ranged from 0.7 to 14.8 percent.

In tests performed in 1963, of 21,152 marked fish released upstream from the barrier net, only 1,239 were recovered at the shore-loading facility, a return of five percent.

Six tests were made in 1961 and 1962 to determine the efficiency of the barrier net pumping system to transfer fish from the skimmer barges to the shore-loading facility. Hatchery rainbow trout and hatchery-reared Snake River fall chinook were used. Recovery of marked test fish ranged from 74 to 100 percent and averaged 90 percent for the six tests.

The artificial currents induced by pumps at the skimmer barges proved inefficient in attracting downstream migrants. The barrier net pumpimg system which transfers fish from the skimmer barges to the shore-loading facility appeared to function satisfactorily.

Juvenile chinook salmon and steelhead trout have been collected at the Brownlee barrier net since 1959. The number of migrant salmon collected at the net has declined from 130,551 in 1959 to 13,482 in 1963. The number of steelhead captured has declined from 18,250 in 1959 to 1,212 in 1963.

The reduction in number of downstream chinook salmon migrants is possibly due in part to decreased numbers of spawners. However, data compiled indicates that major reductions in the number of downstream migrants collected at the barrier net took place before any major reduction in the number of spawners occurred. A major reduction in the number of downstream migrant steelhead collected at the barrier net also occurred before a reduction in the number of spawners.

Since Brownlee Reservoir was created, a steady decline in the number of downstream migrants has occurred. Decreases in the number of downstream migrants captured at the barrier net since 1959 could be the result of factors other than the obvious one of reduced spawning populations. Among these possibilities, one must consider (1) migrants fail to migrate through the long expanse of reservoir; (2) migrants have not been attracted to the collection barges and wander aimlessly or succumb to adverse environmental conditions within the reservoir; (3) migrants have passed through or under the net and past the dam,

-44- During 1963, six large scoop traps were fished in the tailrace and the river downstream from Brownlee Dam to sample the number of fish which pass under or through holes in the barrier net and leave the reservoir via spillway or turbines. On some days the scoop trap catches exceeded the barrier net facility catches. Generally, the catches at the scoop traps increased as the barrier net catches increased and decreased when the scoop trap catches decreased.

In late June and early July, 1963, flows ranging to 40,000 c.f.s. were released at Brownlee Dam. During this same period, large sections of the barrier net below the water surface were removed. These measures resulted in no appreciable increase in the scoop trap catches. However, catches at the barrier net during the first four days the net was open increased more than 200 percent over the catches of the preceding weeks in the month of June.

A large percentage of the fish collected in the scoop traps below the dam were dead. Many of the dead fish examined externally in the tailrace traps showed some evidence of damage resulting from pressure changes. Evidence of pressure change and mechanical injury were observed mostly in chinook and steelhead which were 150 millimeters or more in length.

During 1962, downstream migrating fall chinook salmon and steelhead trout were captured from the Snake River near Weiser, Idaho, marked and released. Spring chinook were captured and marked in Eagle Creek near Richland, Oregon. These fish were captured and marked before they entered Brownlee Reservoir in order to (1) determine with assurance the origin and age of fish collected at the barrier net; and (2) to obtain an estimate of the number of fall chinook entering the reservoir.

Marked fall chinook of the 1961 year class were recaptured at the barrier net in 1962 and 1963. Estimated recruitment to the reservoir ranged from 791,644 fish based on mark and recovery data of fish recovered at the barrier net in 1962, to a recruitment of 546,420 fish based on recaptures of marked fish from 1962 and 1963.

Samples of marked and unmarked fish were measured in 1962 and 1963 in order to facilitate identification of the various races and age classes of fish collected at the barrier net. The Age Class I spring chinook and Age Class 0 fall chinook had rather distinctive length frequency distributions during the spring months. Age Class I fall chinook and Age Class II spring chinook (residuals) had overlapping length frequency distributions.

-45- RECOMMENDATIONS

1, It was not possible during the course of this study to identify, specifically, all the factors contributing to the ineffectiveness of the barrier net to operate as planned. It must be concluded, however, that the barrier net is a failure as a method of collecting downstream migrating salmon and steelhead in Brownlee Reservoir. 2, Research to develop methods of collecting downstream migrating salmonoids from streams prior to their entry into long, deep reservoirs should be accelerated. If a feasible method is developed for collecting ocean-going migrants in Snake River upstream from Brownlee Reservoir and transporting them for release downstream below all long, deep reservoirs in the middle Snake River, the installation of such facilities at the head of the Brownlee pool by Idaho Power Company should be considered. 3. Studies designed to evaluate the effectiveness of fish facilities and their impact on anadromous fish should be initiated in the early planning stage of any dam construction so that adequate testing facilities can be incorporated into the original dam design. 4. Studies to evolve more efficient means of controlling nongame fish movement in fishways than the perforated board developed for Oxbow Dam fishway should be pursued. 5. Studies should be undertaken to investigate the correlation of warmer water in impoundments to the incidence and virulence of C. columnaris and the influence of this disease on fecundity and prespawning mommy of salmon and steelhead in a reservoir habitat.

-46- ACKNOWLEDGMENTS

Many people contributed to this report. Appreciation is expressed to Fishery Biologists Leon W. Murphy and Ted C, Bjornn, and Conservation Educator Michael Throckmorton for their help in reviewing the report and offering valuable suggestions in its preparation. A special note of gratitude is expressed in memory of Wayne C. Klavano, Fishery Biologist, who so ably supervised this study from April, 1961, until his untimely death, which occurred during the performance of his duties, on May 29, 1963.

The cooperation of Mr. Carrol Hill, Supervisor of Idaho Power Company fish facilities at Brownlee and Oxbow Dams, and his personnel is acknowledged with many thanks.

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