The Blue Earth River is a tributary of the Minnesota River. It is 108 miles (174 km) long and can be found in the southern part of Minnesota and the northern part of Iowa in the United States. It has two headwaters: the Middle Branch Blue Earth River and the West Branch Blue Earth River. The Blue Earth River is part of the watershed of the Mississippi River. The river was named for old deposits of bluish-green clay that could be seen along the banks of the river. However, you are no longer able to see these deposits. It was called Makato Osa Watapa by the Dakota Indians. This had the meaning "the river where blue earth is gathered."