Rockland County, NY Environmental Rules: Stormwater Management (2026)

All five Rockland towns are regulated Small MS4s (Municipal Separate Storm Sewer Systems) under NY DEC's SPDES General Permit GP-0-15-003. Each town adopted a local Stormwater Management Law (Clarkstown Ch 178, Ramapo Ch 195-A, Orangetown Ch 28A, Haverstraw, Stony Point) implementing six minimum control measures: public education, public participation, illicit discharge detection and elimination, construction site runoff, post-construction stormwater, and municipal good housekeeping. SWPPPs are required for disturbances ≥1 acre (project-site); projects discharging to impaired waters or within 500 feet of a regulated waterbody may trigger Enhanced Phosphorus Removal standards. Post-construction requires green infrastructure / Runoff Reduction Volume per the NY Stormwater Management Design Manual (2015 with 2020 updates). The Rockland County Drainage Agency, established under NY County Law, administers certain inter-municipal drainage districts along the Mahwah, Pascack, Sparkill, Hackensack, and Minisceongo creek systems. Illicit connections to storm sewers are prohibited; hotline complaints handled by town stormwater officer.