tion of Columbia River stocks has

be defined by its most important element-water. A multitude of natural resources and commercial interests are dependent upon the region's rivers and oceans. There are rivers, dozens in fact, penetrating a large variety of western terrain and climate. A review of the geography of the land reveals two giants which stand out, the Snake and Columbia Rivers. Together, these form the economic and environmental foundations of the land. Although their physical structure varies greatly, these two rivers share a common denominator - anadromous fish. anadromous fish. These species, which spawn in freshwater and grow to maturity in salt water, are an integral part of the Pacific Northwest.

For centuries the salmon has held a high religious significance for the Indian nations as well as being an important food source. For the white man they are important as a food item and for the millions of dollars they annually bring to our economy. They capture our imagination, luring us with their romantic life cycle of travel, unyielding struggle, and uncompromising death.

Pacific salmon of the genus Oncorhynchus and steelhead trout (Salmo gairdneri) have a unique life cycle. In the ocean they grow fat from

abundant food sources. Here, too, they feel the first twinge of sexual maturity which triggers with unerring accuracy their return to the natal stream. Two to five years in the ocean provides the strong bodies needed to carry them as far as 1000 miles upriver.

Prior to the spring freshet, or runoff, they begin to smolt (a process by which their body changes physiologically in preparation for the completely different environment of salt water). This smolting process triggers the urge to migrate downstream. When temperature and flow unite at appropriate levels, juveniles leave their birth streams and begin the long migration to the sea, traveling the region's major arteries Rivers.

the Snake and Columbia

catch shifted back and forth between Indian and non-Indian fishermen. The decline has been caused by a multitude of factors - overfishing, agricultural pollution, industrial pollution, logging, irrigation withdrawal, blockage from the spawning grounds, and mainstem hydroelectric development.

The Corps of Engineers' role in the damming of the Columbia River began in 1938 with the completion of Bonneville Lock and Dam at River Mile 145. Since then the Corps has constructed McNary (1953), The Dalles (1957), and John Day (1967) on the Lower Columbia; and Ice Harbor (1961), Lower Monumental (1969), Little Goose (1970), and Lower Granite (1975) on the Lower Snake.

The Columbia River system, one of the most productive salmon rivers in the world, still supports a $200 million annual salmon and steelhead trout fishing industry. Declines in the number of salmon have been occurring since the late 1880s, and the utiliza

Extensive hydroelectric development in the lower reaches of these

rivers presents a unique problem for ocean-bound salmon and steelhead trout. The once constant fall of the

of pressure drop along hydraulic shear planes formed at the trailing edge of the Turbine blades, and direct contact with the blades themselves. When the combined turbine mortalities are calculated for the eight Corps projects, the effects are substantial. Low run-off years result in a higher percentage of available flows going through the powerhouse, and impacts to the migrating juveniles are proportionately higher. Mortality over the spillways is much lower, averaging an estimated 1 to 2 percent.

The additional time it now takes for the smolts to travel through the slowflowing reservoirs causes delays in their out-migration. It has been estimated by the National Marine Fisheries Service (NMFS) that prior to dams being in place, smolts took 22 days to get from the Salmon River to the Columbia River below Bonneville Dam, NMFS estimates that with the current impoundments the journey takes 54 days.

tion, adversely affecting the juvenile population.

Finally, when water is released over the spillways it plunges deep into the stilling basin below the dam. This deep plunge causes entrapped air to dissolve into the water at levels higher than saturation. These supersaturated levels cause nitrogen gas, the major component of air, to enter the juvenile fish, creating a condition similar to the "bends." In severe cases an embolism will eventually kill the animal. Structural modifications to many of the Corps spillways have eliminated much of this problem.

To alleviate these mortality, delay, and supersaturation problems, a logical solution was to collect the juveniles at the upper dams and transport them to a release site below Bonneville. Operation Fish Run accomplishes this collection and transportation, and reduces the juvenile migration time to pre-dam levels.

Cross-sectional view of a mainstem

hydroelectric dam.

In carrying out the operation, young salmon and steelhead migrating to the sea are collected at Lower Granite, Little Goose and McNary Dams. Specially-designed tankers and barges are used to transport the fish safely around the remaining dams to release sites below Bonneville Dam. Once there, the juveniles can freely move to the estuary and ocean without further delay.

The collection systems utilized in Operation Fish Run, although complex in reality, are quite simple in theory. They were designed in response to research which has shown that juvenile salmonids prefer to inhabit the top 12-15 feet of the water column. This causes them to enter the upper portion of the turbine's intake.

A traveling screen, which serves as the heart of the collection system, deflects the juveniles up into the gatewell slots. From here the fish are attracted by lights to exit via orifices into the collection channel within the dam. This channel transports the juveniles around the dam to holding facilities below. The young fish are then separated from the collection water and placed into hatchery-like raceways. From the raceways they can easily be loaded into trucks or barges, or guided into a building for marking, examination, and species composition calculations.

Operation Fish Run was initiated in

1971 and maintained in a research mode through 1976. The severe regional drought of 1977 forced state and Federal fisheries management agencies to take immediate action. Juvenile transportation was reviewed, deemed successful, and the decision was made to continue on a larger scale.

In 1977, with the addition of two fish transportation barges to the existing fleet of five 3500-gallon trucktanker units, the scope of Operation Fish Run changed dramatically. This added transportation capacity allowed the number of transported juveniles to more than double.

thereby allowing the juveniles to "imprint" on the river water during the entire two-day trip downriver. This imprinting process enables the returning adults to detect or "smell" their natal stream accurately. Juveniles transported directly from the hatcheries to the estuary often lack this "imprint." They display confused migratory patterns, straying into side rivers along the migration route. They are often delayed from, and sometimes fail, to return to the hatcheries.

Traveling screen being lowered into the gatewell slot at Lower Granite.

The number of juveniles collected and transported during the 1978 to 1980 period increased drastically (Figure 1). This increase in the number transported is a result of good years of both hatchery and wild-stock production, and increased collection capacities. A chronological presentation of the period from 1978 to 1980 is presented below.

The Pacific Northwest experienced a year of near normal water runoff in 1978. Large adult returns to the spawning grounds (escapement) in 1976 brought large numbers of outmigrating juveniles in 1978. The five tankers and two fish barges were used to haul a record 5,422,000 smolts.

In 1978 a research program was initiated at McNary Dam to evaluate the newly completed fish protection and collection facilities. Conducted by the National Marine Fisheries Service under contract to the Corps of Engineers, a major effort was made to observe the condition of the juveniles and to start up the fingerling bypass and separator systems. Tests were also begun on the initial use of three traveling screens at McNary. Juveniles collected that year were used for research purposes and returned to the river.

In addition, field testing of a fishguiding device designed to be as effective as the traveling screen, but much less costly, was begun in 1978 at McNary. This was a bar-scoop screen designed to guide juveniles into the

gatewell slots without the expensive and troublesome moveable aspects of the traveling screen. Three bar-scoops were installed and tested. Results indicate that although guiding efficiency was comparable to the traveling screen for most size classes of juveniles encountered, the cost of maintaining an adequate backflushing system (debris removal) was prohibitive. Based on these studies all screens purchased since then have been the traveling type.

In 1979 water run-off was again near average. That year all 12 turbine intakes at Little Goose and Lower Granite were screened for the first time. A total of 36 traveling screens