Abiotic Changes Within a Reservoir After a Complete Drawdown: A Case Study of Lake Griffy

Abstract

Aquatic ecosystems are created and dictated by their physical and chemical environment; when catastrophic events cause an ecosystem shift, such as the draining and refilling of a reservoir, the composition and quality of the ecosystem state can change based on the new physical and chemical environment. This research project examines the physical and chemical limnological changes in Griffy Lake, Bloomington, IN, after the complete drawdown of water for the purpose of dam reconstruction. After two years of sediment oxidation and terrestrial plant growth, the reservoir naturally refilled. The study summarizes recovery results from data collected on a monthly basis. The results focus on the variables of temperature, dissolved oxygen, alkalinity, pH, specific conductance, and nutrient concentrations. After analysis of the data, this project will allow for better understanding of the effects of complete drawdowns on abiotic variables. The work presented is part of a larger project that will examine how aquatic ecosystems recover and ecosystem states may shift within reservoirs after complete drawdowns. With more than 75,000 dams across the United States, many of which are approaching the end of their life spans, in the near future it is important to understand how such events affect the quality of the water, in addition to aquatic ecosystems.