San Mateo County, CA Environmental Rules: Stormwater Management (2026)

The discharge of Non-Stormwater to the County Storm Drain System is prohibited. All discharges of material other than Stormwater must be with a NPDES Permit and this ordinance. It is unlawful for any Person to commence or continue any Illicit Discharge to the County Storm Drain System. This prohibition applies to all connections made to the County Storm Drain System. Alteration is inclusive of all connections made in the past, regardless of whether made under a permit or whether permissible under the law or practices applicable or prevailing at the time of the connection to the County Storm Drain System. Connections that pre-date the passage of this ordinance must receive written permission from the Director of the Department of Public Works or their designee to continue with the discharge of Non-Stormwater materials.

(Ord. No. 4913, § 1, 11-4-2025)