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|Title:||Effects of reservoir releases on water quality, macroinvertebrates, and fish in tailwaters : field study results|
|Authors:||National Reservoir Research Program (U.S. Fish and Wildlife Service)|
Environmental and Water Quality Operational Studies (U.S.)
Walburg, Charles H.
Novotny, Jerry F.
Jacobs, Kenneth E.
Swink, William E.
|Publisher:||Environmental Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
Abstract: This report summarizes field investigations conducted at seven reservoirs in 1979 and 1980 to determine the effect of reservoir releases on tailwater biota. The study sites differ greatly in project purpose, depth of water release from the reservoir, and location and are representative of many U.S. Army Corps of Engineers reservoirs throughout the United States. Studies were conducted in tailwaters below both flood-control and peaking hydropower projects. Effects of reservoir discharge were most evident near the dams where environmental stress was most severe; farther downstream the effects were moderated. The invertebrate and fish communities in tailwaters were affected most by the temperature, volume, and timing of the discharges. High levels of iron and manganese occurred in most tailwaters, but their effects on invertebrates and fish were not addressed in this study. The numbers of invertebrate and fish species were largest in tailwaters of flood-control projects with warmwater release and smallest in tailwaters of large hydropower projects. Invertebrate populations were seasonally more stable, although less diverse, in tailwater of hydropower projects than in tailwaters of flood-control projects. The uniform operation of the hydropower projects provided a relatively constant downstream environment for the few species present. Periodic flood discharges in the tailwaters of flood-control projects severely altered the tailwater environment and disrupted the invertebrate community. Fish were most abundant in tailwaters of flood-control projects with warmwater release and least abundant in tailwaters of large peaking hydropower projects. Sunfishes, suckers, and catfishes were most important in tailwaters of flood-control projects; stocked trout provided the major fishery in the cold tailwaters of deep-release hydropower projects. Fish populations in the warmwater tailwaters were most similar to those in natural streams and were apparently least affected by dam operations. Fishes in cold tailwaters of deep-release hydropower projects were most affected by dam operations. The occurrence of diverse habitats in tailwaters (backwaters, deep pools, fallen trees, and large boulders) may moderate the effects of dam operations on both invertebrates and fish. NOTE: This file is large. Allow your browser several minutes to download the file.
|Appears in Collections:||Technical Report|