Big Muddy National Fish and Wildlife Refuge Clark was considerably different from today's river. The historic Missouri was a broad, slow-moving, shallow river with braided channels. These past river conditions created a haven for wildlife, which included vast floodplain forests of giant trees, marshes, and even wet prairies. Today's river is channelized. It is deeper and faster, and controlled by levees, dikes, and other containment structures. These controls make the river more navigable and the surrounding floodplain ideal for agriculture. The Big Muddy Refuge is allowing the Missouri River to be a river again, to enter its floodplain. This occurs during minor flood events. Management has created
Muddy River (Washington) rapidly, passing under Forest Road 25 and then receiving Clear Creek from the left about from the mouth. At the road crossing, Muddy Creek Picnic Site is on the left. Below the confluence with Clear Creek, the river meanders through Cedar Flats, leaves the national forest slightly more than a mile from the mouth, and passes a United States Geological Survey (USGS) stream gauge, on the left from the mouth. Muddy River enters the Lewis River about from the larger stream's mouth on the Columbia River. The USGS monitors the flow of Muddy River at a station upstream of the