Hawthorne, CA Environmental Rules: Stormwater Management (2026)

020 prohibits any illicit discharge into the municipal separate storm sewer system (MS4) unless it falls under one of three narrow exceptions: NPDES-authorized nonstormwater, firefighting activity, or a discharge specifically exempted by the Los Angeles Regional Water Quality Control Board. 030 separately bans illicit connections that convey such discharges into the MS4. 040 requires any facility or activity that needs a state NPDES stormwater permit to obtain one before discharging to the MS4, and to keep on-site records including its notice of intent, waste discharge identification number and stormwater pollution prevention plan (SWPPP) for city inspection.

050 bans dumping, spilling, leaking or burying solid or liquid waste, including pollutants, into the MS4 or onto any public or private property in the city, and separately bans disposing of leaves, dirt or other landscape debris into the MS4, banned pesticides or herbicides into the MS4, or hazardous material into any civic litter container. 060 requires owners and occupants of premises exposed to stormwater, particularly parking lots over 25 spaces tied to industrial or commercial SIC-coded activity, to implement best management practices to reduce pollutant discharge to the maximum extent practicable.

070 requires grading permit applicants disturbing five or more acres to file a notice of intent under the state construction stormwater permit and prepare a SWPPP before the city issues any grading or building permit. 100, abatable by the city.