Prior Lake. Prior Lake, MN. Prior Lake is a city 20 miles (32 km) southwest of downtown Minneapolis in Scott County in the U.S. state of Minnesota. Surrounding the shores of Lower and Upper Prior Lake, the city lies south of the Minnesota River in an area known as South of the River and establishes the urban fringe of the south-southwest portion of Minneapolis-St. Paul, the sixteenth largest metropolitan area in the United States. The population of Prior Lake was 22,796 at the 2010 census. Seen as the sister city of Shakopee, Prior Lake was incorporated as a village in 1851, Prior Lake is one of the oldest southern metro cities to have been absorbed by suburban growth.