Impingement and Entrainment of Fishes at Dairyland Power Cooperative's Genoa Site

Abstract

The impact to the fishery of Navigation Pool No. 9 of the Mississippi River from impingement and entrainment processes by two Dairyland Power Cooperative power stations in Genoa, Wisconsin, was determined. Impingement samples were taken once each week for a 24 hour period from 8 August 1978 through 30 June 1980 at both plants. Sampling devices, comprised of galvanized hardware cloth, were used to strain screen wash water to determine impingement rates. Entrainment sampling was conducted once each week for a 24 hour period from 26 February 1979 through 10 September 1979 and 6 February 1980 through 30 June 1980. Entrainment rates were determined by straining water from tapped intake pipes with plankton nets. Impingement survival tests, stress tests, and ichthyoplankton surveys were also taken to further define the impact of entrainment and impingement.

An estimated 8,390 (127.1 kg) and 54,349 (2915.7 kg) fish were impinged during this study at La Crosse Boiling Water Reactor. (LACBWR)and Genoa #3 (G-3), respectively. The two power stations collectively impinged representatives of 53 species and 19 families of fish. The most frequently impinged species of fish were bluegill (Lepomis macrochirus), freshwater drum (Aplodinotus grunniens)., gizzard shad(Dorosoma cepedianum) and channel catfish (Ictalurus punctatus). Young-of-the-year fish density, behavioral responses of some species of fish and intake structure design were determined to be the most influential factors causing impingement at these plants. The impact to the Pool 9 fishery from impingement by these two power stations was judged insignificant. Greater than 11 x 106 larval fish were entrained by G-3 during this study. Freshwater drum and Morone sp. larvae were the most frequently entrained species of fish. Other larval fish taxa entrained were Dorosoma sp., Hiodon sp., Pomoxis sp., cyprinids and catostomids. The impact to the Pool 9 fishery from entrainment was probably insignificant with the possible exception of freshwater drum.

Recommendations for modification of screen washing procedures and intake structures at the present plants were offered to the power company to reduce the impact of entrainment and impingement. Placement of intake structures in areas of lowest fish density was recommended to the power company for their future power plants.