In June 2018, the Lake County Stormwater Management Commission (SMC) entered into a contract with Christopher B. Burke Engineering, Ltd. to study the Upper Des Plaines River Watershed (DPRW) within Wisconsin and the potential impacts in Wisconsin and Illinois due to development in that region.
The study area includes the Foxconn Technology Group development site, which is part of the Electronics, Information Technology and Manufacturing Zone (EITM Zone). This area is immediately upstream of Lake County and encompasses a major source of surface water. To address watershed-wide flooding and water quality impacts, the study recommends that wetland mitigation, floodplain management, and stormwater storage and erosion control practices for this area are planned, designed and enforced.
"Flooding and water quality issues don't stop at the state line," said Craig Taylor, SMC Chairman and District 19 Lake County Board Member. "It's imperative that we're looking at environmental issues and impacts in both Illinois and Wisconsin so we can protect residents and businesses in both states."
The impact analysis consists of a multi-phased review to objectively identify the magnitude of stormwater, floodplain and wetland impacts, and mitigation methods in the EITM Zone. The initial results from the analysis were presented at the Stormwater Management Commission board meeting on March 7.
Four major areas of concern were outlined.
- Floodplain definition and floodplain management criteria: Analysis of the DPRW suggests the floodplain in Wisconsin is underestimated, which leads to underestimation of flood risk for businesses and residents near the floodplain.
- Development site stormwater storage/depressional storage: There is a stormwater and floodplain compensatory storage deficit of approximately 55,000 gallons for every acre developed in the EITM Zone when compared to Lake County regulations.
- Wetland impact and mitigation criteria: Thirty-eight acres of wetlands and waters have been filled within the DPRW from the EITM Zone and related roadway development without any mitigation yet created within the watershed. This number will likely grow if development in the area continues, and the current approach is not modified to require mitigation within the DPRW.
- Soil Erosion and Sediment Control Practices: Sediment is being transported from construction sites downstream to the Des Plaines River. One of the Illinois Environmental Protection Agency listed causes for impairment in the Des Plaines River is land development activity.
"In addition to the areas of concern that were discovered during the study, the report also provides detailed recommendations to address those outlined issues," said Mike Warner, SMC Executive Director. "It is critical that these four major issues are addressed in order to help mitigate flooding concerns in both Wisconsin and Illinois as well as to ensure the health of the DPRW."
Initial results from the study are available on the SMC website and will be open for public review and comment until April 8. Any comments about the draft report should be sent to Stormwater@lakecountyil.gov.