Antioch, CA Environmental Rules: Stormwater Management (2026)

Illicit discharge into Antioch's municipal separate storm sewer system (MS4) is expressly prohibited under Antioch Municipal Code Chapter 6-9 (Stormwater Management and Discharge Control), which implements the Federal Clean Water Act 33 USC 1342(p) and the Municipal Regional Stormwater NPDES Permit (MRP 3.0, Order R2-2022-0118) issued by the San Francisco Bay Regional Water Quality Control Board. An illicit discharge is any discharge to the MS4 that is not composed entirely of stormwater, with limited exceptions for permitted flows (firefighting, water line flushing, irrigation runoff, diverted stream flows, etc.). Common illicit discharges that trigger enforcement include: sanitary sewer overflows, mobile auto detailing wash water, restaurant grease and food-waste dumping, concrete washout, paint and drywall slurry, pool drainage with chlorine, pesticide and herbicide application runoff, illegal dumping of motor oil and antifreeze, construction site sediment, and commercial equipment washing. Antioch Code Enforcement and Public Works staff investigate reports, trace discharges to sources using dye testing and CCTV when needed, and issue notices of violation. Administrative penalties under AMC 1-3 can reach $1,000 per violation per day for repeat offenses, and the state Water Board can add penalties up to $10,000 per day per violation under California Water Code 13385 for significant discharges. Commercial and industrial facilities must often enroll in the state Industrial General Permit if they have qualifying activities. Report illicit discharges by calling Antioch Public Works at (925) 779-6950 or CalEPA's waste hotline at 1-800-698-6942.