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

Mendocino County is a permittee under the State Water Resources Control Board's Phase II MS4 Small Municipal Separate Storm Sewer System General Permit (Order 2013-0001-DWQ). Stormwater Runoff Pollution Prevention is regulated by Chapter 16.30 of the Mendocino County Code, adopted October 4, 2011, with jurisdiction over the urbanized areas surrounding Ukiah and Fort Bragg that fall within the County's regulated NPDES MS4 stormwater permit area. The county must adopt requirements identifying appropriate Best Management Practices to control the volume, rate, and potential pollutant load of storm water runoff from new development and redevelopment projects. Any project that disturbs less than one acre of soil must comply with the site development and stormwater runoff provisions of the California Green Building Code and Best Management Practices. Projects of one acre or more must obtain coverage under the State Construction General Permit (Order 2009-0009-DWQ as amended) and prepare a Storm Water Pollution Prevention Plan. In the Coastal Zone, Title 20 Division II adds Chapter 20.492 (Grading, Erosion and Runoff) and Chapter 20.717 (Water Quality Protection), which extend stormwater and erosion controls to all coastal parcels regardless of MS4 status. The City of Fort Bragg uses the Mendocino County Low Impact Development (LID) Manual to ensure NPDES compliance.