Sedimentation in the channel is caused by the normal cycle of silt movement, erosion from high water or heavy rains and changes in river currents. To maintain the 9-foot navigation channel, material that settles in the channel area must be removed. Mechanical or hydraulic dredging are methods for the removal of that material.
This material is placed in designated areas along the river. Some of these areas are beneficial use placement areas. Beneficial use of dredged material is the productive use of the material by the public or private sectors. Examples of common beneficial uses of dredged material in the St. Paul District are upland habitat development, wetland creation, aquatic habitat enhancement, creation of areas for bird nesting, beach nourishment, winter road maintenance, levee repair and improvement, aggregate for concrete, lining fly ash pits, bank protection and general purpose fill.
The district is responsible for maintaining 243.6 miles of navigation channel to a depth of at least 9 feet on the Mississippi River from Minneapolis at river mile 857.6 to Guttenberg, Iowa, at river mile 614.0, and 40.6 miles on three tributaries: the Minnesota, St. Croix and Black rivers.