Big Stone Lake
Big Stone Lake,
narrow lake, c.25 mi (40 km) long, on the Minn.–S.Dak. line. Located in the outlet channel of glacial Lake AgassizAgassiz, Lake, glacial lake of the Pleistocene epoch, c.700 mi (1,130 km) long, 250 mi (400 km) wide, formed by the melting of the continental ice sheet beginning some 14,000 years ago; it eventually covered much of present-day NW Minnesota, NE North Dakota, S Manitoba, central
..... Click the link for more information. , it is the source of the Minnesota River and serves as a storage reservoir for the Minnesota Valley.