Streambed elevations of the Missouri River near Kansas City and St. Joseph, Missouri, have degraded about 10 feet since the closure of the large mainstem reservoirs above Gavins Point, South Dakota, in the mid-1950s. Whereas streambed degradation seems to have stabilized at St. Joseph since about 1995, degradation at Kansas City continues at a rate that may be slightly accelerating. Degradation in Kansas City caused record low water levels in 2003 and 2004 and is of concern for many water users in and near Kansas City. Data from the U.S. Army Corps of Engineers indicate little or no degradation downstream from Waverly, Missouri and upstream of St. Joseph. The cause and future of streambed degradation in Kansas City are unknown. Local sand dredging, decreased sediment from upstream resulting from reservoir trapping, channel response to construction of navigation structures, and channel shortening immediately downstream of Kansas City are potential causes or contributors to streambed degradation. To decrease and plan for the effects of streambed degradation, the processes, cause, extent, and future of degradation near Kansas City need to be determined.

Although the cause of streambed degradation in Kansas City is unknown, the effects are numerous. Power and municipal water supply utilities in Kansas City are rebuilding intakes or adding cooling towers. Recently constructed boat ramps are not in water and unusable during low flows. Lower streambed elevations in the Missouri River also can be expected to extend up into tributaries, causing similar concerns with structures and to affect riverine habitats. Pipelines, channel-control structures, and even bridge piers may be in jeopardy.

Another effect of streambed degradation is a decline in ground-water levels in the adjacent alluvial aquifer, which can result in drier wetlands. Decreases in ground-water levels of even 1 or 2 feet can decrease wetland sustainability by increasing the rate of water loss through wetland bottoms and can drastically change water levels and water quality in riparian wetlands, such as Little Bean Marsh immediately north of Kansas City. Changes in water level and water quality of a wetland are primary controllers of the vegetative and ecological character of a wetland. In fact, Little Bean Marsh has been mostly dry for several years in response to lower stages on the Missouri River. Because streambed degradation and resultant decreases in water levels have occurred slowly over decades, changes to wetlands along the river may go unnoticed. Other wetlands in the Kansas City area that may be affected by declining ground-water levels include Cooley Lake, Jackass Bend, Horseshoe Lake, and Mud Lake. Quantification of the effects of bed degradation on these wetlands would help characterize the threat to wetlands at other locations along the Missouri River where streambed degradation has been documented, such as Sioux City, Iowa and Hermann, Missouri.