The headwaters of the Grand River begin from natural springs in Somerset Township in Hillsdale County near the boundary with Liberty Township in Jackson County.[6] From there, the river flows through Jackson, Ingham, Eaton, Clinton, Ionia, Kent, and Ottawa counties before emptying into Lake Michigan. The river runs through the cities of Jackson, Eaton Rapids, Dimondale, Lansing, Grand Ledge, Portland, Ionia, Lowell, Grand Rapids, and Grand Haven.
The Grand River is a major tributary of Lake Michigan. It falls in elevation from 1260 ft. in the highlands of its headwaters to 577 ft. at its mouth on Lake Michigan. Its waters drain northward through the lake, then south and east through the Great Lakes waterways into the St. Lawrence River, which flows northeasterly into the Gulf of St. Lawrence on the Atlantic Ocean. The Grand River discharges an estimated average 5,049 cubic feet per second (143.0 m3/s).[2]
Its watershed is the second-largest in the state, draining an area of 5,572 square miles (14,430 km2), including 18 counties and 158 townships. Much of the basin is flat, and it contains many swamps and lakes. The basin is composed of four sub-basins: Upper Grand, Lower Grand, Thornapple, and Maple, where the four major tributaries flow: the Flat, Rogue, Thornapple, and Maple rivers.
