Lake Restoration: A Five-Year Evaluation of the Mirror and Shadow Lakes Project Waupaca, Wisconsin

摘要

Mirror and Shadow Lakes, small seepage lakes in central Wisconsin, had experienced cultural eutrophication as a result of storm water drainage. Storm sewers were diverted from the lakes in 1976 and in 1978 aluminum sulfate was applied to enhance the recovery rate by reducing internal phosphorus loading from the sediments. Mirror Lake was artificially circulated to prevent low winter oxygen concentrations and increase spring oxygen concentrations. Storm sewer diversion reduced external phosphorus loading from 58 - 65 percent for both lakes while the aluminum sulfate application reduced inlake phosphorus concentrations from 90 mg/cu m and 55 mg/cu m in Mirror and Shadow Lakes respectively to 20-25 mg/cu m. Diversion of the storm sewers resulted in a decrease in epilimnetic phosphorus and nitrogen concentrations.