The 1972 Clean Water Act requires municipalities across the United States to take steps to reduce point source discharges of stormwater runoff into surface waters. In 1990 the EPA’s National Pollutant Discharge Elimination System (NPDES) published stormwater regulations that were separated into two phases. Phase I required large urban municipalities to control pollution and MDE began issuing Phase I permits in 1993. However, the City falls under the second phase, Phase II, which regulates small municipalities, and some state and federal agencies. MDE issued the first Phase II general permit in 2003. The general permit was reissued in late 2018 with more stringent requirements.
The Phase II general permit requires the implementation of six minimum control measures (MCMs) which include:
1. Public Education and Outreach
2. Public Involvement and Participation
3. Illicit Discharge Detection and Elimination
4. Construction Site Stormwater Runoff Control
5. Post-Construction Stormwater Management
6. Pollution Prevention and Good Housekeeping
In addition to the above minimum control measures, the 2018 Phase II general permit also includes a requirement to provide treatment for 20% of runoff that is not currently being treated by modern stormwater management practices by 2025.