Lake Jefferson is a lake in Le Sueur County, Minnesota, United States. The lake covers an area of 1,141 acres (4.62 km²) and is 37 feet (11 m) deep at its deepest point. Fish species enzootic to Lake Jefferson include bluegill, largemouth bass, northern pike, and walleye. While the Geographic Names Information System considers Lake Jefferson to be a single lake, it is sometimes referred to as two lakes, East Jefferson Lake and West Jefferson Lake.