The impetus of this project was to assist the Washington Department of Fish and Wildlife (WDFW) Banks Lake Fishery Evaluation Project to improve and maintain the ecological diversity and quality, and beneficial uses of the fish resources of Banks Lake, Washington, an equalizing and power-generating reservoir for the Columbia Basin Irrigation Project. Water level fluctuations through seasonal inundation and drawdowns may alter the spawning and rearing habitat for fishes in Banks Lake. The combination of attributes, such as providing food, shelter, and reproductive sites for other organisms, and the influence on water quality, suggest that natural shorelines provide many essential functions for lakes. The loss of littoral habitat has been identified as a potential causative or contributing factor to the low abundance of certain game fishes. However, there has been no empirical evaluation of the impacts of water level fluctuations on fish habitat and productivity, either at the typical 1.5 m summer drawdown level, or the 3 m summer drawdown level being proposed by the U.S. Bureau of Reclamation for Banks Lake. The goal of this project was to quantify the loss of shoreline habitat and aquatic vegetation during a 1.5 m elevation change on Banks Lake, Washington, and evaluate the effects of habitat loss to fish distribution.
We assisted the Banks Lake Fishery Evaluation Project being conducted by the WDFW by completing the following objectives:
1) Ecological shoreline classification: Working in conjunction with WDFW biologists, the Banks Lake shoreline was classified into habitat/ecosystem types, using a combination of aerial photo interpretation and field observations.
2) Quantification of littoral habitat losses: Using a combination of Geographical Information Systems (GIS) and methods developed by the Geo-ecology Research Group (GRG) to quantify wetland losses (Gabriel and Bodensteiner 2002), the annual loss of littoral habitat through 1.5 m lake level drawdowns were quantified for each shoreline habitat type from digital aerial photographs collected by WDFW contractors.
3) Ecological characterization of shoreline habitat reference sites: Reference sites were established for each shoreline habitat type, each sampled to characterize the aquatic vegetation, substrate, and fish found at each habitat type.
4) Banks Lake habitat map: A GIS database and associated maps were created for Banks Lake, including shoreline habitat designations, reference sites, relative losses of littoral habitat types, and a pre-Columbia Basin Project map of the Banks Lake region's shoreline (circa 1949).
Washington Department of Fish and Wildlife.
Dates of Project: 05/03-12/03
Summer Students Funded: 2
Gabriel, A.O., K. Lillquist, and L. Jordan. 2004. Shoreline Habitat Characterization and Analysis for the Banks Lake Fishery Evaluation Project. Washington Department of Fish and Wildlife Research Contract Report. Geo-ecology Research Group Research Report 10. Ellensburg: Central Washington University. 61 pp.
Gabriel, A., L. Jordan, and K. Lillquist. 2004. Nearshore habitat impacts of lake level drawdowns, Banks Lake, Washington. Presented at the Northwest Scientific Association 77th Annual Meeting, Central Washington University, Ellensburg, Washington, March 24-27 2004.
Gabriel, A., L. Jordan, K. Lillquist, and T. Barnhart. 2004. Nearshore habitat impacts of lake level drawdowns, Banks Lake, Washington. Presented at the North American Lake Management Society 24th International Symposium, Victoria, B.C., November 3-5 2004.