CHAMPAIGN, Ill., 2/9 /18: In the Chicago region, rain and snowmelt often overwhelm sewer systems, causing street flooding and basement back-ups. Pollutants from sewer systems flow into nearby rivers and Lake Michigan. Even in areas with separate storm and sanitary sewers, overflow from severe storms carries pollution into the Chicago area waterways system, adversely affecting water quality and habitat. This problem is expected to worsen as climate change progresses and storms grow larger and more frequent.

In 2017, The Metropolitan Planning Council, The Nature Conservancy, and the Metropolitan Water Reclamation District in Cook County collaborated on a feasibility study to consider stormwater credit trading as an alternative to creating on-site facilities for site development or redevelopment.

As part of this study, the collaborators contracted a team of engineers and hydrologists at the Illinois State Water Survey (ISWS), joined by U of I Department of Landscape Architecture staff, to assess the land area that has the potential for off-site stormwater management facilities in suburban Cook County, excluding the City of Chicago. These areas would provide trading credit for detention or volume control of stormwater when a development cannot meet the requirements on-site. Off-site storage upstream of the development site could reduce peak flows and provide additional benefits to the area.

The team’s analysis showed there are ample sites in the Chicago region to provide a supply of off-site facilities, which could be developed by private companies or communities. These stormwater landscapes, sometimes called “landscape as infrastructure,” become highly important public and environmental spaces in municipalities. Recent research has revealed that stormwater landscapes create multiple benefits to communities visually, educationally, socially, and environmentally.

The ISWS team developed the publication, Land and Hydrologic Analysis for Stormwater Detention and Volume Control Trading Exchange in Cook County, Illinois, detailing the results of their analysis. They also contributed to the publication, Stormstore: A Feasibility Study Examining Stormwater Credit Trading in Cook County.