Southborough, MA Environmental Rules: Stormwater Management (2026)

Southborough regulates stormwater through two bylaws. Chapter 154, Stormwater and Erosion Control (adopted 3-25-2023, Article 30), governs runoff from new development and redevelopment and is enforced by the Conservation Commission. Chapter 225, Illicit Discharge (adopted 4-10-2006, Article 45), governs what enters the municipal storm drain system and is enforced by the Board of Health.

Section 154-1(B) requires that new development, redevelopment and all land conversion activities maintain after-development runoff characteristics as equal to or less than pre-development runoff characteristics. The Commission applies this through § 154-9(A), which bars approval unless there is no net increase in the rate of runoff, no net increase in volume across the site boundaries (subject to the storm drain tie-in and Commission-determination exceptions quoted above), and no adverse impact to abutting properties. Under § 154-5(D) the Commission uses the latest edition of the Massachusetts Stormwater Management Policy for design and sizing criteria.

The applicant submits a stormwater management and erosion control plan and an operation and maintenance plan prepared, stamped and signed by a professional engineer registered in Massachusetts, a registered land surveyor, or a Massachusetts licensed soil evaluator, as appropriate (§ 154-5(E)). The O&M plan remains on file with the Commission, the Planning Board, the Department of Public Works and the Town Engineer. At completion, § 154-9(D) requires as-built record drawings of structural stormwater controls, certified by a professional engineer. Section 154-2 defines redevelopment as construction, alteration or improvement exceeding land disturbance of 5,000 square feet where the existing land use is commercial, industrial, institutional, or multifamily residential.

On the drain side, § 225-7 prohibits dumping or discharging any pollutant or non-stormwater discharge into the municipal separate storm sewer system, a watercourse, a wetland resource area or the waters of the commonwealth, bars illicit connections, and bars obstructing the flow of stormwater into or out of the storm drain system without prior written approval from the Board. Section 225-8 exempts fire fighting, waterline flushing, sump pumps, landscape irrigation or lawn watering, noncommercial car washing, and dechlorinated pool water of less than one ppm chlorine.