The Illinois Green Infrastructure Study

By Martin Jaffe, Moira Zellner, Emily Minor, et al
Chicago, IL (May 28, 2010)- This report explores the science of green infrastructure practices and evaluates existing and potential policies, regulations and administrative tactics that could be adopted in the State of Illinois to promote the widespread, appropriate use of green infrastructure stormwater management strategies and techniques.

Green infrastructure practices, for purposes of this study, are urban stormwater management techniques that rely on natural systems to retain more stormwater on-site through infiltration, evapotranspiration and harvesting for reuse. Implementing green infrastructure practices helps attenuate nutrients and other pollutants and reduce runoff volumes and peak flows.
Based on our review of peer-reviewed scientific reports and articles, we found that, on average, many of these practices are as effective as conventional on-site detention basins in reducing total suspended solids and total nitrogen being discharged to waterways and that they can also reduce runoff volumes and peak flows discharged to urban streams, reducing erosion, sedimentation and flood risks. Using an economic model, we also found that using green infrastructure can result in substantial savings in both construction and life-cycle costs when compared to using conventional infrastructure to manage runoff in suburban, urban residential and commercial projects.
Research addressing the valuation of ecosystem services also suggests that using green infrastructure can provide significant indirect economic benefits, as well, by increasing the amount of open space, vegetation, habitat and groundwater recharge occurring in developed areas. Since there is considerable experience in using green infrastructure in northeastern Illinois and in five other states we surveyed – and since green infrastructure is already required under the state’s General NPDES Permit No. ILR40 (“the MS4 permit”) — we conclude that promoting the greater use of these practices would be a cost-effective way for Illinois to improve urban stormwater management programs and the water quality of our lakes and streams. It would have the additional benefit of helping municipalities covered by the MS4 permit to meet their legal responsibilities.

Related Resources:

The Illinois Green Infrastructure Study
2010 Green Infrastructure Summit