Merced County, CA Environmental Rules: Stormwater Management (2026)

53 implements the county's NPDES Phase II small municipal separate storm sewer system (MS4) permit. 020(A) prohibits discharging or causing to be discharged into the storm drain system any pollutant or material other than stormwater, and separately bans illicit connections to that system, including connections made in the past regardless of whether they were once lawful. A short list of exempt discharges exists: water line flushing, individual residential car washing, diverted stream flows, uncontaminated groundwater, air conditioning condensation, dechlorinated swimming pool water, and firefighting flows, so long as they are not determined to violate the Porter-Cologne Act or Clean Water Act.

020(C) separately makes it unlawful to throw or leave refuse, rubbish, garbage, or litter on any street, alley, sidewalk, driveway, or storm drain component. 020(E) requires anyone responsible for irrigation runoff beyond incidental amounts to detect and correct sprinkler leaks within 72 hours, aim sprinkler heads properly, and avoid irrigating during rain events. Industrial and construction operators holding an NPDES permit must prove compliance with that permit before the county will approve a subdivision map, building permit, or improvement plan. 040. 080(F), and that decision is final.