Measurement of Lake Roosevelt Biota in Relation to Reservoir Operations; 1992 Annual Report.

The purpose of this research project is to collect data to model resident fish requirements for Lake Roosevelt as part of the Bonneville Power Administration (BPA), Bureau of Reclamation (BoR), and U.S. Army Corps of Engineer`s (ACE) System Operation Review. The System Operation Review (SOR) is a tri-agency team functioning to review the use and partitioning of Columbia Basin waters. User groups of the Columbia have been defined as power, irrigation, flood control, anadromous fish, resident fish, wildlife, recreation, water quality, navigation, and cultural resources. Once completed the model will predict biological responses to different reservoir operation strategies. The model being developed for resident fish is based on Montana Department of Fish, Wildlife, and Parks model for resident fish requirements within Hungry Horse and Libby Reservoirs. While the Montana model predicts fish growth based on the impacts of reservoir operation and flow conditions on primary and secondary production levels, the Lake Roosevelt model will also factor in the affects of water retention time on zooplankton production levels and fish entrainment. Major components of the Lake Roosevelt model include: (1) quantification of impacts to zooplankton, benthic invertebrates, and fish caused by reservoir drawdowns and low water retention times; (2) quantification of number, distribution, and use of fish food organisms in the reservoir by season; (3) determination of seasonal growth of fish species as related to reservoir operations, prey abundance and utilization; and (4) quantification of entrainment levels of fish as related to reservoir operations and water retention times. This report contains the results of the resident fish system operation review program for Lake Roosevelt from January through December 1992