Chelsea, MA Environmental Rules: Stormwater Management (2026)

Stormwater management in Suffolk County is driven by federal, state, and local regulations. The four Suffolk municipalities each hold EPA Small MS4 General Permits (issued 2018, reissued 2022) that require illicit discharge detection, construction site runoff controls, and post-construction stormwater management. Boston Water and Sewer Commission (BWSC) administers stormwater rules under BWSC Stormwater Management Standards — new development or redevelopment disturbing 5,000+ sq ft of impervious surface must submit a stormwater management plan, meet 80% TSS removal, and comply with the 10 MassDEP Stormwater Standards in 310 CMR 10.05(6)(k). Chelsea enforces its Stormwater Management Ordinance (Chapter 10, Article XIV) with jurisdiction over any land disturbance of 1+ acre or 10,000 sq ft if in a sensitive area. Revere Stormwater Management Ordinance (Chapter 12.32) requires a permit from the Department of Public Works for disturbances of 1+ acre. Winthrop adopted the MAPC model stormwater bylaw. All discharge to wetlands triggers the Wetlands Protection Act (MGL c. 131, §40) and requires an Order of Conditions from the local Conservation Commission. Illicit connections to the MS4 system — such as sanitary sewer cross-connections, wash water, or chemical dumping — are prohibited under all four local ordinances and 314 CMR 21.00.