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Evaluating an Illinois River Floodplain Restoration Project's Effects on Water Quality
Emiquon, an hour south of Peoria along the Illinois River, is home to one of the largest floodplain restoration projects (totaling 7,000 acres) in the country outside of the Florida Everglades. Once the jewel of the Illinois River, Emiquon supported diverse, abundant communities of native plants and animals in a complex system of backwater wetlands and lakes. In 1940, Emiquon and much of the floodplain was isolated from the Illinois River by a levee. Active pumping keeps the area drained and a large portion of the property along the river has been under intensive corn cultivation. The property was recently purchased by The Nature Conservancy (TNC), whose goal was to restore the property to a native, pre-disturbance floodplain ecosystem. TNC has developed a restoration plan, which calls for the site to be flooded and reconnected with the river. TNC considers this its premiere demonstration site for work within the Upper Mississippi River Basin (UMRB), and hopes that it will help guide other floodplain restoration efforts. The Illinois Water Survey has completed preliminary site hydrology studies and a sedimentation model. The two problems that may hamper the restoration's efficacy are related to the decreased health and water quality of the Illinois River: increased stressor and pollutant loads since 1940 (suspended sediments, nutrients, toxic pollutants) and invasive species that now inhabit the River.
Wetlands have been recognized for their potential to retain sediments, nutrients, and contaminants and the Presidential Watershed Nutrient Task Force has identified wetland restoration as one of the actions necessary to address the hypoxic zone in the Northern Gulf of Mexico. Understanding how Emiquon's restoration effects water quality may help scientists conceptualize the impact of excess nutrients from the Midwest on hypoxia in the Gulf of Mexico. Within the UMRB, Illinois, Iowa, and Missouri have lost 85%, 89%, and 87% of all wetlands, respectively; Minnesota and Wisconsin have lost approximately half of their wetlands.
In order to estimate the acreage of wetlands necessary to reduce nutrient loads to the Gulf of Mexico, we must understand the uptake of nutrients within restored wetlands. We must design a monitoring protocol for restored wetlands to monitor these areas and determine their processing of these and other pollutants (sediments, toxicants, pathogens). We must know how these pollutants will affect the success of floodplain and wetland restoration, and water quality downstream. EPA will learn about performing flood plain restoration on a large scale and the effects of restoration on water quality.
Proposed Studies: NRMRL and Region 5 propose to partner with TNC, USGS, and universities to:
- a) monitor the water quality of discharges from the Emiquon site prior to, during, and posterior to restoration; and
- b) design protocols for determining the pollutant-processing effectiveness of restored floodplain wetlands.
Contact: Joseph Schubauer-Berigan (EIMS#136285)