GLWA has prepared a comprehensive hydrology and hydraulics model for its service area using the US EPA Storm Water Management Model (SWMM) software as part of its Long-Term Combined Sewer Overflow (CSO) Plan to address water quality issues under the National Pollutant Discharge Elimination System (NPDES) administered by the Michigan Department of Environment, Great Lakes, and Energy (EGLE). Although this model has been developed over the last several decades and is being used successfully to guide necessary improvements for water quality per the NPDES program, the model does not adequately represent the issues associated with rainfall-related flooding to guide decision-making relative to rain events beyond the 10-year 1-hour design storm used to initially develop the combined portions of the collection system. The scale of the region and issues to be addressed require a focused effort of federal, state, and local partners to develop feasible, implementable, and affordable alternatives to address the problems associated with regional flooding and water quality. The region is also committed to incorporating “engineering with nature” opportunities, as evidenced by the extensive park, greenway, blueway, and green stormwater initiatives that have been built and are being considered throughout the region. Further, the tributary systems managed by entities in Washtenaw, Macomb, Oakland, and Wayne Counties provide additional opportunities and infrastructure that may be considered in addressing the significant flooding experienced by the City of Detroit and contiguous communities.
