Date of this Version
Historically, the Missouri River was a shallow, shifting river well known for muddy waters and rapidly changing channel conditions. The dynamic river provided a wide range of depth, velocity and sediment conditions. Within this environment, the amount of shallow water habitat was quite prevalent, with estimated amounts of more than 100 acres per mile. Shallow water habitat is an aquatic area less than five feet deep where the river flows slowly – less than two feet per second.
Over the years, the U.S. Army Corps of Engineers has been charged by Congress to remove snags, protect banks, construct navigation channels and build flood risk management structures (levees and dams) on the Missouri River to provide social and economic benefits to the nation. The Bank Stabilization and Navigation Program often relied on deposition of river sediments within constructed dike fields to train the river to a single channel. The resulting channel is at a fixed location and is both faster and deeper flowing than the historical river. While the ongoing operation of these projects continues to provide significant economic benefits, these activities have also diminished many natural features of the river’s historical condition, including river flow variation, habitat diversity, sediment loads, water temperatures and floodplain connectivity. Compared to the historical abundance of shallow water habitat, the river in the late 1990s was estimated to provide less than five acres per mile of shallow water habitat within the lower 750 miles of the Missouri River.