New EPA Draft Permit Targets Stormwater Pollution
On October 31, the Environmental Protection Agency released the long-awaited draft permit for private commercial, industrial, and institutional (CII GP) stormwater discharges in the Charles, Mystic, and Neponset River Watersheds.
The Neponset River faces multiple water quality issues, including pollution from pathogens and nutrients like phosphorus and nitrogen, which are worsened by urban development. Stormwater carries these nutrients into waterbodies, which can cause algal blooms that are harmful to aquatic life, degrade water quality, and limit recreational activities like boating, fishing, and swimming.
While cities and towns have made significant progress in reducing pollutants under the Municipal Storm Sewer System (MS4) permit, which regulates municipal storm drains, pollution from privately owned or unregulated sources remains a significant issue.
Large private commercial, industrial, or other entities (including multi-family parcels) contribute nearly three-quarters (70%) of the Watershed’s total estimated phosphorus load, despite representing just 22% of all parcels in the Watershed.
Due to the highly paved nature of these parcels, they contribute an outsize amount of the total phosphorus load (34%). The CII GP permit aims to reduce total phosphorous by 60% across the Watershed.
Compliance with the new regulations is proposed based on property size, with large contributors having to comply first. Only sites with one acre or more of impervious surface would be required to comply with the permit.
Part of the new regulations include the creation of a stormwater pollution control plan (SPCP) for each permittee. Offsite mitigation will be allowed if onsite reduction isn’t feasible.
The EPA is accepting public comments on the draft permit until January 29, 2025. For more information, go to: https://www.epa.gov/npdes-permits/notice-preliminary-designation-certain-stormwater-discharges-commonwealth
NepRWA has a long history of working to reduce water pollution in the Neponset Watershed. Through the Neponset Stormwater Partnership (NSP), we collaborate with 13 towns—Avon, Canton, Dedham, Foxborough, Medfield, Milton, Norwood, Quincy, Randolph, Sharon, Stoughton, Walpole, and Westwood—to improve water quality and meet new stormwater regulations. Learn more at www.yourcleanwater.org
