The purpose of this project is to contribute to the understanding of the processes that control community structure, productivity and abundance of planktonic organisms in lakes. It will maintain the continuity of a long-term study of Lake Washington that was started in 1949 and has been continuous since 1961. The response of the lake to an earlier episode of pollution with secondary sewage effluent and its recovery after diversion showed that the lake could respond promptly to changes in input of nutrients. The goal now is to measure the way the biological and chemical conditions of lake change in response to natural variations in external factors such as weather and hydrology, and to various kinds of human activity. The major changes are expected to be in land development and management of fisheries. The result will provide a useful base for evaluating the effect of foreseen future changes. Changes in biological and chemical conditions in 1988 suggest that the lake is currently being affected by changes in land use. A study of the new conditions and an attempt to identify the specific causes and processes of change should be rewarding for both scientific and practical purposes.
