Investigations were made to determine the feasibility of radical drawdown as a restoration technique for Lake Apopka, Florida, a 12,545 hectare lake in central Florida. Field studies showed the lake to be hypereutrophic with continual algal blooms, mats of floating water hyacinths, and a flocculent organic muck bottom rich in interstitial water nutrients. Sediments were dredged from the lake bottom and placed in aquaria, columns, tanks and pools. Following dewatering and varying drying periods, the containers of sediment were refilled. A large number of physical, chemical and biological parameters were monitored before, during and following sediment drying. Results indicate that drawdown improves subsequent refill water quality. Based on these laboratory scale investigations, drawdown appears to be an effective restoration technique for Lake Apopka.

Prepared by University of Florida, Gainesville, Fla., for U.S. Environmental Protection Agency, Office of Research and Development, Corvallis Environmental Research Laboratory, under grant no. R800305. Includes bibliographical references (pages 88-90).