Glades Wetland Complex Habitat Restoration
St. Louis District
Illinois River, Miles 12 - 20, Jersey and Calhoun Counties, Illinois, Congressional District: IL - 13
- Illinois Department of Natural Resources
- US Fish and Wildlife Service
The proposed project includes Glades Management Area, Twelve Mile Island, Helmbold Island, and Mortland Island. The project area is located on the lower Illinois River between river miles 12 - 20 in Jersey and Calhoun counties and encompasses approximately 2,644 acres. Glades Management Area is part of an un-leveed floodplain on the left descending bank. Helmbold Island was an isolated island in 1940, but has since merged with the mainland on the right descending bank. Twelve Mile and Mortland Islands are independent from the mainland. These sites are General Plan (GP) lands owned by the US Army Corps of Engineers and are managed by the Illinois Department of Natural Resources through a cooperative agreement with the US Fish and Wildlife Service.
The Upper Mississippi River Habitat Needs Assessment (2000) has identified the need for restoring depth and connectivity in backwaters of the lower Illinois River and improved water management that mimics historic natural river elevations. Backwater habitat on the lower Illinois River has been degraded due to sedimentation and substrate suspension, reducing the quantity and quality of submersed aquatic vegetation and fishery habitat. Current water level management tires to mimic natural river conditions during the summer by drawing down the backwaters and allowing the sediments to consolidate, increasing backwater depth and reducing sediment suspension. However, current drainage systems, low berms and pumps do not facilitate efficient water level management.
Twelve Mile and Mortland Islands: There has been loss of deep water and side channel habitat for fishes due to siltation of the side channels. The occurrence of sunken woody structures would improve feeding and resting areas for the fish and invertebrates
Glades Management Area: Currently the site does not drain properly as the drainage channels have silted in. The drainage gates are too small allowing water to be trapped in the backwater for a longer period of time following the spring flood pulse. The backwater does n ot have sufficient depth to function as a backwater habitat for fishes. Lack of water level management capability negatively impacts the floodplain forests and establishment of more desirable mast producing tree species.
Helmbold Island: Sedimentation has filled in most of the side channel around Helmbold Island. The remaining channel is isolated from the river most of the year degrading its effectiveness as a fishery. A small backwater has also become isolated from the river and no longer functions as an effective fishery. Lack of water level management capability negatively impacts the floodplain forests and establishment of more desirable mast producing tree species.
- Approximate Acres: 2650
- Congressional District: IL - 13
- State(s) Covered: IL
- Land Ownership: U.S. Army Corps of Engineers
- Management Agency: ILDNR
- Management Authority: Cooperative Agreement
Proposed Potential Features
Twelve Mile and Mortlands Islands:
- Chevrons could be used to enhance the flow and scouring through the side channels around the islands.
- Multiple structures could be placed in the side channels to provide fishery habitat
Glades Management Area:
- Water control structures
- Pump Station
- Excavation of primary and secondary channels
- Excavation of backwater areas (pothole wetlands)
- Construction of a low berm that creates a separate management unit, deflects sediment, and improves water level management
- Dredging of side channel
- Excavation of backwater areas
- Construction of a low berm to improve water level management and to deflect sediment
- Water control structures
- This project has been endorsed by the River Resource Action Team
- Fact Sheet completed in June 2010