what county is prairie du sac wi in?
Downtown Prairie du Sac. Prairie du Sac is a village in Sauk County, Wisconsin, United States. The population was 3,972 at the 2010 census. The village is surrounded by the Town of Prairie du Sac, the Wisconsin River, and the village of Sauk City; together, Prairie du Sac and Sauk City are referred to as Sauk Prairie.