Lilly Lake is located in southeastern Wisconsin. It has a surface area of 37 ha and in 1977 had a maximum depth of 1.8 m and a calculated infilling rate of 0.5 cm per year. The basin contained up to 10.7 m of lightweight, organic sediments. Recreational activity was severely restricted due to periodic winter fish kills and dense growths of macrophytes throughout the summer. During the open water periods of 1978 and 1979, 683,000 cu m of sediment were removed with a 30-cm cutterhead dredge and transported via pipeline to two disposal sites. The dredging operation deepened the lake to a maximum of 6.6 m and afforded an excellent opportunity to evaluate the inlake and disposal site effects of the project. The inlake portion of the investigation included an assessment of water quality, aquatic biology, sediments, and hydrology before, during, and after completion of dredging. The evaluation of sediment disposal emphasized the impact on the nearby groundwater system and the value of using hydrosoils to enhance agricultural crop production.