In 1974, the Wisconsin Legislature recognized that many lakes needed more intensive management than could be provided by either the state's general pollution control efforts or the voluntary efforts of property owners' associations. The Legislature passed legislation enabling property owners to form a special purpose unit of government to manage a local lake. This article describes the history and activities of Wisconsin lake districts. Particular attention is paid to the differentiation of function between federal, state, and county/municipal governments – general purpose units – and the special purpose lake district. Data from a recent survey of 79 lake districts showed the most popular activities are mechanically harvesting aquatic vegetation, 57 percent; stocking fish, 48 percent; promoting boating and skiing regulations, 37 percent; chemically controlling macrophytes, 34 percent; controlling algae, 33 percent; patrolling water safety, 28 percent; promoting zoning, 25 percent; inspecting septic tanks, 25 percent; and providing public access, 25 percent. Such management efforts indicated lake districts have become a significant institution in the management of Wisconsin lakes.