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Habitat Restoration Planning in the Middle Mississippi River
Midwest Region, September 12, 2007
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 The Marion, Illinois Ecological Service Field Office recently completed a Draft Fish and Wildlife Coordination Act Report for the Herculaneum Reach Wing Dike Modification Project.  The project area is located between Upper Mississippi River miles 156.3 and 149.7 in Monroe County, Illinois and Jefferson County, Missouri.  The Corps of Engineers considers this reach their “prototype” for maintaining the 9-foot navigation channel.  By 1966, various river training structures constructed by the Corps has contracted this reach to an average width of 1800 feet and lowered the riverbed by 8 feet.  Continued construction from 1967 to 1969 narrowed the river channel further to 1200 feet and lowered the riverbed an additional 3 feet.  By 1971, the low-water riverbed in this reach was on average 11 feet lower than in 1889.  The river training structures are so effective that the Corps rarely has to dredge in this reach to maintain the navigation channel.

Constricting the Mississippi River channel in such a way has reduced the amount of sidechannel and shallow water habitats available to aquatic resources, including the endangered pallid sturgeon.  In recent years, the Corps has been working with the Fish and Wildlife Service and the states to evaluate various reaches of the Mississippi River in order to restore and enhance aquatic habitat.  Part of this effort was the completion of a dike inventory and analysis of the entire Middle Mississippi River in 2002.  This study identified 4 dike fields with 29 structures as occurring within the 7 mile Herculaneum Reach. 

The evaluation was taken one step further in 2003 with completion of a Hydraulic Sediment Response Study (micro-model) to evaluate various alternatives for modifying dikes to restore aquatic habitat while maintaining the integrity of the navigation channel.  The best alternative identified the possibility of restoring 3 separate sidechannels which will total approximately 3.0 miles in sidechannel length.  Additionally, shallow water, sandbar habitat will develop adjacent to the sidechannels which will further increase habitat complexity in the reach.

The Carterville Fisheries Resources Office has been conducting pre-project fisheries monitoring in this reach.  During Year 1 of monitoring a total of 3,331 fishes from 54 species were captured.  This included 2,149 adults (49 species) and 1,182 young-of-year (29 species).  Within wing dike habitats, the most abundant adult species were emerald shiner and common carp.  The most abundant young-of-year species were freshwater drum and channel shiner.  It is anticipated that restoration of habitat complexity will benefit large river fish of concern to the Service, including pallid sturgeon, shovelnose sturgeon and paddlefish.  A strong post-project monitoring component is recommended as part of the project in order to fully evaluate project assumptions and to make adjustments to future projects accordingly (adaptive management).

In addition to habitat associated impacts from Corps activities in this reach of the Middle Mississippi River, the area has also been impacted by unauthorized releases of lead and heavy metals from the Doe Run Lead Smelter facility in Herculaneum.  The potential presence of contaminated sediments was a consideration during project development.  To avoid the potential to remobilize and transfer contaminants downstream, no modifications will occur within the dike fields in the vicinity of Joachim Creek.  Additionally, data gathered by the Fish and Wildlife Service Contaminants Program indicates that the concentrations of lead and other heavy metals in the areas where dike modifications will occur have been reduced to levels such that adverse effects are not likely to occur to fish and wildlife resources.  However, the Service has recommended additional deep core sediment sampling in the areas where sidechannels are predicted to form to ensure contaminant levels remain below concentrations of concern. 

Planning for this project is expected to be completed in 2008, with construction to begin soon after authorization of the Navigation and Environmental Sustainability Program in the next Water Resources Development Act.

Contact Info: Larry Dean, 612-713-5312, Larry_Dean@fws.gov



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