When Cities Choose Green

Stormwater flooding is a growing challenge for cities and communities globally, exacerbated by expanding impervious surface under urbanization and more frequent extreme rainfall under climate change. Green stormwater infrastructure (GSI) has the potential to reduce flood risk while providing valuable co-benefits, but is not always well-aligned with or supported by existing policy and planning requirements. This study evaluates the adoption of municipal policies promoting GSI within the Rouge River Watershed (RRW) in southeast Michigan, USA. We analyze the policies of 43 municipalities in the watershed to determine their degree of support for GSI, including financial incentives and land use and redevelopment requirements. Then, we use regression analyses to explore how socio-economic, capacity, and land use characteristics are associated with GSI-supportive policies. We find significant variability in policy adoption among municipalities and GSI types. Large/regional scale GSI projects, such as retention and detention systems, generally find more support from municipalities than small/onsite scale projects like rain gardens and permeable pavement. We also find that larger municipalities with more employees per capita are more likely to have policies favorable to GSI. Overall, municipal support for GSI in land use policies and regulations is fragmented and relatively weak, which is likely to inhibit implementation and pose a challenge to broader regional collaboration within the watershed.