The Regional Water Quality Control Board regulates municipal stormwater discharges under the federal Clean Water Act and California’s Porter-Cologne Water Quality Act through issuance of National Pollutant Discharge Elimination System (NPDES) permits for stormwater discharges from municipal separate storm sewer systems (MS4s).
Contra Costa County’s current NPDES Municipal Regional Permit (MRP) No. CAS612008 (PDF) was reissued by the San Francisco Bay Regional Water Quality Control Board in 2022. The MRP was issued to all municipalities and flood management agencies in Alameda, Contra Costa, San Mateo, and Santa Clara counties, and within Solano County, the cities of Fairfield, Suisun City, and Vallejo, and the Vallejo Flood and Wastewater District.
The Contra Costa County Watershed Program administers the MRP for unincorporated Contra Costa County and the Costa County Flood Control and Water Conservation District.
The MRP contains a comprehensive plan to reduce the discharge of pollutants in stormwater to the "Maximum Extent Practicable" in order to protect water quality. To accomplish this, the MRP is comprised of the following provisions, relevant to Contra Costa County:
(C.2) Municipal Operations
(C.3) New Development and Redevelopment
(C.4) Industrial and Commercial Site Controls
(C.5) Illicit Discharge Detection and Elimination
(C.6) Construction Site Control
(C.7) Public Information and Outreach
(C.8) Water Quality Monitoring
(C.9) Pesticides Toxicity Control
(C.10) Trash Load Reduction
(C.11) Mercury Controls
(C.12) Polychlorinated Biphenyls (PCBs) Controls
(C.13) Copper Controls
(C.15) Exempted and Conditionally Exempted Discharges
(C.17) Discharges Associated with Unsheltered Populations and Homelessness