|Document Type:||Contract Report|
|Title:||Effects of water-borne pollutants on fish passage at John Day Dam, Columbia River|
|Author/Editor:||David M. Damkaer|
|Publisher:||National Marine Fisheries Service|
|Contracting Agency:||U.S. Army Corps of Engineers, Portland, Oregon|
Like other hydroelectric projects on the Columbia River, John Day Dam has facilities for passage of migratory adult salmonids. These facilities include a fish collection system along the downstream face of the powerhouse and a fishway with auxiliary water-supply systems on both sides of the river. John Day Dam has been shown to cause delays in the upstream migration of adult spring chinook salmon, Oncorhynchus tshawytscha. During the 1979 and 1980 spring migration periods, average passage times for radio-tagged fish were 158 h and 156 h, respectively. This compares unfavorably to less than 2 d for fish passing Bonneville and less than 1 d for fish passing The Dalles Dam.
Within the limits of project design, altered flows and configurations have not improved fish passage. Delays have not been significantly decreased by changing entrance locations, water discharge volumes, or turbine operating conditions. There has always been a distinct preference for fish to use the south fishway, which is not a problem in itself, but which may ultimately suggest reasons for the general delay. Because there is evidence that the delay at John Day Dam has caused increased adult mortality and reduced spawning success, it is necessary that additional efforts be made to identify and moderate causes of delay.
It is believed that water-borne pollutants, especially fluorides, may have a potentially negative influence on fish passage. Many of the monitored elements and compounds did not appear to have gradients within the John Day Dam region, and therefore the observed delays of salmonids would not likely be attributable to these constituents.
Some of these elements were not investigated beyond the first two or three cruises. Although of little value in the present study, observations on these constituents provide a useful chemical background to this middle stretch of the Columbia River and to the mouth of the John Day River. In view of the expense of such intensive chemical analyses, especially of the organic components, it is not likely that a comparable broad assay would be repeated soon.
Results of this first year of investigation (1982) are preliminary. There is some evidence to link pollutants from the aluminum production plant to the delay of salmonids at John Day Dam, but this is not conclusive. Better real-time observations on fluoride content, particularly, to correlate with fish-passage through the fishways are planned for 1983. Also, it will be essential to consider the behavior of adult and juvenile salmonids while in gradients of fluoride comparable to gradients found in the John Day Dam region.
Such bioassay studies are proposed for next year and will be conducted at the University of Washington experimental hatchery at Big Beef Creek, on Hood Canal. Investigations into the possible effects of the organic pollutants from the aluminum plant should be undertaken, especially in view of their buildup in the sediments upstream from the dam. Additional studies on the effects of these organic compounds are not planned for next year, but we do intend to look further into the extent, persistence, and influence of heavy metal ions, particularly copper, zinc, and cadmium.