Cottage Grove is a city located in Washington County, Minnesota. As of the 2000 census, the city had a total population of 30,582.
According to the United States Census Bureau, the city has a total area of 98.2 km2 (37.9 mi2). 88.0 km2 (34.0 mi2) of it is land and 10.2 km2 (3.9 mi2) of it is water. The total area is 10.39% water.