Using Green Infrastructure to Support Municipal Separate Storm Sewer System Program Compliance

As stormwater flows, it picks up pollutants like trash, chemicals, oils, and dirt or sediment that can harm our rivers, streams, lakes, and coastal waters. Polluted stormwater is commonly transported from impervious surfaces into a conveyance system (the MS4) and then discharged—untreated—into local water bodies. To prevent harmful pollutants from being washed or dumped into MS4s, certain operators are required to obtain National Pollutant Discharge Elimination System (NPDES) permits. Communities with coverage under an MS4 permit must develop a stormwater management program describing the stormwater control measures that will be implemented to minimize the discharge of pollutants from the storm sewer system. Some MS4 permits require specific and measurable water quality improvements, especially where stormwater is discharged to impaired water bodies with an approved total maximum daily load.

Green infrastructure can help communities meet their goals and permit obligations by treating stormwater and creating green space. Green infrastructure is a key technique used for treating post-construction runoff, which regulated MS4s must address in their programs. Implementing green infrastructure also provides opportunities for resident outreach and engagement, which aligns with MS4 program goals for public education and outreach as well as public involvement and participation.

Green Infrastructure Permit Compendium

MS4 permits can be written to require green infrastructure implementation. EPA reviewed numerous state- and EPA-issued MS4 permits and compiled a variety of permitting approaches that require green infrastructure using clear, specific, and measurable permit terms and conditions in its Green Infrastructure MS4 Permit Compendium (pdf). This compendium also provides examples of how MS4 permittees implement green infrastructure permit requirements. The static map below shows the locations of permit excerpts included in the compendium.

Resources

• EPA's Green Infrastructure MS4 Permit Compendium (pdf)
• EPA's Green Infrastructure Permitting and Enforcement Series: Factsheet 4 – Stormwater (pdf)
• EPA's National Menu of Best Management Practices (BMPs) for Stormwater: Post-Construction
• EPA's Stormwater Smart Outreach Tools
• Green Infrastructure Modeling Toolkit
• Visit the EPA Resources page to learn about the variety of EPA tools that can be used to support planning and design decisions for implementing green infrastructure.