Potters Marsh Habitat Rehabilitation and Enhancement Project

Rock Island District

Pool 13, Upper Mississippi River Miles 522.5 - 526.0, Carroll and Whiteside Counties, Illinois, Congressional District: Illinois - 17




Construction of Lock and Dam 13 raised the river level, creating a permanent backwater slough between what is now an island and the Illinois mainland bank. To provide access to the Corps of Engineers (Corps) Thomson Causeway Recreation Area, the Corps raised an existing causeway near the upstream end of the slough. The causeway has culverts that are large enough to pass high flow levels carrying large amounts of sediment. Siltation in the slough had reached a critical point. Submergent vegetation totally clogged most of the slough, drastically reducing the fisheries habitat. Additionally, siltation had filled in much of the historically productive waterfowl marshes at this location.
Backwater hydraulic dredging has restored and created deep water slough habitat for overwintering fish. Creation of a sediment trap has kept the upper end of the slough and causeway flow tubes from silting in completely. Construction of a managed marshland provides a migratory bird feeding resting area. Pothole excavation has made additional secluded open water available for waterfowl. Implementation of the project, as designed, has improved the quality and effective lifetime of this valuable wetland-upland complex.

Quick Facts

  • Approximate Acres: 2,305 (Sources: DPR and Operations & Maintenance Manual)
  • Congressional District: Illinois - 17
  • State(s) Covered: Illinois
  • Land Ownership: U.S. Army Corps of Engineers
  • Management Agency: U.S. Fish and Wildlife Service, U.S. Army Corps of Engineers
  • Management Authority: Refuge


  • Dredge 24,100 lineal feet (394,000 cubic yards) for fishery enhancement
  • Dredge 2,100 lineal feet above and a deep hole below the causeway (49,000 cubic yards) to serve as a sediment trap
  • Drill one well with submergible pump
  • Construct a confined placement site (CPS)
  • Improve and extend an existing road to the CPS
  • Establish a 32.5 acre marshland on the CPS surface,which includes a stoplog structure and a 7 acre grassland area
  • Create 18 isolated potholes for waterfowl use 


  • The Definite Project Report was completed in 1992.
  • Project construction was initiated in 1993 and completed in July 1996.
  • The Operation and Maintenance Manual was completed in 1997.
  • Performance Evaluation Reports were completed in 1998, 2002 (update) and 2003.
  • Performance monitoring continues.