Anadromous salmonids of the Hanford Reach, Columbia River: 1984 status

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Abstract

The Hanford Reach, a regulated but flowing section of the Columbia River, supports spawning populations of fall chinook salmon and steelhead. It also serves as a migration route for upriver runs of chinook, coho and sockeye salmon, and of steelhead. Environmental studies conducted in association with activities on the Hanford Site provide a basis for assessing present ecological conditions in the Hanford Reach. Spawning populations of fall chinook salmon at Hanford increased dramatically after 1960, when Priest Rapids Dam was completed, and have remained relatively stable since 1969. Generally, upriver runs of spring, summer, and fall chinook salmon have been depressed, but the fall run has been increasing since 1980. Habitat modification represents the greatest threat to sustained production of fall chinook salmon in the Hanford Reach. Operations on and near the Hanford Site releases of small amounts of radioactivity from onsite operations to river and groundwater, and operation of a steam electric plant, can have negligible effects on salmonids and other aquatic resources. Possible activities with potential future impacts include development of a multi-unit power plant complex at Hanford, construction of a low-head hydroelectric dam above Richland, flow fluctuations from peaking power generation at Priest Rapids Dam, irrigation andmore » reductions of instream flows, and dredging and commercial navigation above Hanford. If reproducing populations of fall chinook salmon and steelhead are to survive in the mid-Columbia River, the Hanford Reach must remain flowing, undeveloped for navigation, and with unimpaired water quality. 156 refs., 16 figs., 7 tabs. « less

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