The Matanuska River (Dena'ina: Ch'atanhtnu; Ahtna: Ts'itonhna’) is a 75-mile (121 km) long river in Southcentral Alaska, United States. The river drains a broad valley south of the Alaska Range eponymously known as the Matanuska Valley. Course Formed by the confluence of its east and south forks, the Matanuska River flows generally southwest to the Knik Arm of Cook Inlet. Downstream of its source, the river is joined by meltwater from Matanuska Glacier in the northern Chugach Mountains. From there it continues through the Matanuska Valley, between the Chugach Mountains to the south and the Talkeetna Mountains to the north. Population centers along its course include Chickaloon, Sutton, Palmer, and Butte. It enters the Knik Arm of Cook Inlet about southwest of Palmer and about northeast of Anchorage. The Glenn Highway runs roughly parallel to the river for much of its length. Highway bridges over the river, listed from source to mouth, include Glacier Park Bridge, Chickaloon River Bridge, King River Bridge, Old Glenn Highway Bridge, and Glenn Highway Bridge. An Alaska Railroad bridge crosses the river parallel to the Glenn Highway Bridge at Palmer Hay Flats State Game Refuge. Mantanuska Glacier State Recreation Site is along the highway where Glacier Creek enters the river; King Mountain State Recreation Site is near Chickaloon, and Kepler – Bradley Lakes State Recreation Area is near Palmer. In addition to the glacier, named and unnamed streams that drain the Talkeetna and Chugach ranges feed into the river. These include Glacier, Hicks, Purinton, Caribou, and Coal creeks, and the Chickaloon and King rivers, and many others. The main stem is silty with glacial run-off from spring through fall but at lower flows beneath winter ice, it runs relatively clear. The Matanuska Valley is one of the most settled regions of Alaska and one of the few areas in the state to support agriculture. Erosion by the glacial braided river has damaged roads, farms, houses, and houses for decades. Discharge The United States Geological Survey operates a stream gauge near Palmer. Mean monthly discharge at this gauge varies from in March to in July. The maximum recorded flow was on August 10, 1971, after the break-out of a natural reservoir on Granite Creek. The minimum recorded flow of occurred on April 25, 1956. Boating The river is a popular destination for whitewater enthusiasts who float mainly in rafts or kayaks. Accessible at several bridges and