Stormwater Management in Chicago: A Cost-Benefit Analysis of the McCook Reservoir, Green Roofs, and Rain Barrels

March 2022

This cost-benefit analysis evaluates stormwater management options in Chicago by comparing the welfare effects of the McCook Reservoir expansion to green roofs and rain barrels, two leading forms of green stormwater management promoted by the EPA. Cook County, Illinois, has invested heavily in its Tunnel and Reservoir Plan (TARP), which serves as the region’s primary means of stormwater management. Based on our findings, Chicago should invest in green stormwater infrastructure to supplement the TARP, maximize co-benefits, and proactively address climate change’s intensifying impacts. First, the city should consider a subsidy program to incentivize residential green roofs. Then, if funds remain, Chicago should further research the most cost-beneficial scenarios for targeted rain barrel programs, such as a public awareness campaign on their benefits in high-risk, flood- prone areas. Expanding green roof programs to encourage broader residential implementation—ultimately, doubling the city’s existing green roof space—would improve stormwater management, limit combined sewage overflows (CSOs), and better prepare Chicago for increased rainfall.