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 (Nevada) to the Colorado River and followed it westward. In 1844, the expedition of John C. Frémont discovered a cutoff route that avoided the Colorado River, following a route between Resting Springs in California, and the Virgin River Valley that passed through Las Vegas Springs and crossed the Muddy River near modern Glendale. Mormon pioneers blazed a wagon road from Salt Lake City to Los Angeles along this pack trail in 1847, followed by Forty-niners attempting avoid the winter snows of the Sierra Nevada Mountains, and wagon trains of Mormon colonists on their way to settle in San Bernardino in 1852.