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Plymouth County, MA Environmental Rules: Stormwater Management (2026)

Some Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

Key Facts

Permit
MassDEP permit required
CGP Threshold
1 acre disturbed
Local Program
MS4 stormwater bylaws
Enforcement
MassDEP and EPA

Summary

Under the Massachusetts Clean Waters Act, no one may discharge pollutants, including construction stormwater, into waters of the commonwealth without a valid permit from MassDEP. Coastal Plymouth County towns enforce local stormwater bylaws under the federal MS4 permit.

City-specific rules exist: Brockton has its own stormwater management rules that differ from Plymouth County's county-level regulations. If you live in Brockton, check the city-specific page instead.

No person shall discharge pollutants into waters of the commonwealth nor construct, install, modify, operate or maintain an outlet for such discharge or any treatment works, without a currently valid permit issued by the director.

Source: Massachusetts General LawsView official code

Full Breakdown

The Clean Waters Act, MGL c.21 §43, bars discharging pollutants into any waters of the commonwealth without a currently valid permit. Across Plymouth County, from the Jones River in Kingston to Buzzards Bay at Wareham and Mattapoisett, MassDEP and EPA administer these permits. Construction sites disturbing one acre or more need coverage under the EPA Construction General Permit and must keep a stormwater pollution prevention plan on site. Towns like Plymouth, Duxbury, and Marshfield run regulated MS4 stormwater programs, requiring erosion controls, illicit-discharge rules, and post-construction treatment of runoff before it reaches wetlands or the bay.

Violations & Fines

Discharging construction or polluted stormwater without a valid permit violates the Clean Waters Act and draws MassDEP enforcement, daily penalties, and orders to cease work. Local MS4 bylaws add their own fines.

Frequently Asked Questions

Do I need a permit for construction stormwater in Plymouth County?
Yes. Sites disturbing one acre or more need EPA Construction General Permit coverage and a stormwater pollution prevention plan. Discharging without one violates the Clean Waters Act.
Who enforces stormwater rules across Plymouth County towns?
MassDEP and EPA enforce state and federal permits. Towns such as Plymouth and Marshfield add local MS4 bylaws with their own erosion and discharge controls.

Sources & Official References

Other rules in Plymouth County

Animal Ordinances: Dog Leash LawsSome RestrictionsAnimal Ordinances: Chickens & LivestockSome RestrictionsCoastal DevelopmentHeavy RestrictionsFlood ZonesHeavy RestrictionsErosion ControlSome RestrictionsFence Regulations: Retaining WallsFew RestrictionsAnimal Ordinances: Exotic PetsHeavy RestrictionsAnimal Ordinances: BeekeepingFew RestrictionsLandscaping Rules: Artificial TurfSome Restrictions

All Plymouth County rules

Compare Plymouth County to another location·View the Massachusetts environmental rules overview

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Stormwater Management in Cities Across Plymouth County

Brockton, MA