Cottonwood Island Habitat Rehabilitation and Enhancement Project
Rock Island District
Pool 21, Upper Mississippi River, Miles 328.5 - 331.0, Lewis County, Missouri, Congressional District: Missouri - 9
Historically, Cottonwood Chute provided deep water habitat, and numerous low swales on the island provided important wetland habitat. Siltation has greatly reduced the quantity and quality of these habitat areas. Sedimentation has been acute in the upper end of the chute and in timbered portions of the island fronting the main channel. Dissolved oxygen values have fallen to critical levels and fish species diversity has decreased in the shallowing portion of the chute.
Mechanically dredging Cottonwood Chute would provide overwintering habitat for fish in the dredged deep holes. Planting mast-producing trees such as pin oak, bur oak, swamp white oak, pecan, and sycamore would enhance habitat value by introducing a mast-producing component into a forest dominated by silver maple and cottonwood. Excavating potholes would restore sloughs and depressions impacted by sedimentation and provide secluded habitat for migratory bird nesting and feeding. It is anticipated that flow will increase in the vicinity of the notched wing dams, deepening the pool behind the wing dams. The change in flow at one wing dam may also stimulate an in-stream meander to the next wing dam. A meander would create deeper areas, which would attract a diverse benthic community and fishery.
- Approximate Acres: 463 (Source: Operations & Maintenance Manual)
- State(s) Covered: Missouri
- Land Ownership: U.S. Army Corps of Engineers
- Management Agency: MO Department of Conservation
- Management Authority: Cooperative Agreement
- Mechanically excavate lower 4,900 feet of Cottonwood Chute to a 9-foot depth with 4 deep holes 15 feet deep
- Plant mast producing trees on dredged material, three Forest Management Areas, and an agricultural field
- Excavate 4 acres of potholes (5)
- Notch 6 wing dams 100 feet to the original river bottom at staggered locations
- The Definite Project Report (DPR) was completed in 1996.
- Construction was initiated in 1997, and complete in 2001.
- The dedication ceremony was held in July 2000.
- The project has been turned over to the MDOC for operation and maintenance, with an Operation and Maintenance Manual completed in 2001.
- An initial performance evaluation report (PER) was completed in June 2001, with a supplemental report in 2002.
- Performance monitoring continues.