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

Adopted by Ord. 1352 (eff. , and the state's Porter-Cologne Water Quality Control Act. Because Yolo County falls under the State Water Resources Control Board's Phase II 'Small MS4 General Permit,' the county had to adopt a Stormwater Management Program (adopted December 7, 2004) and back it with an enforceable prohibition. Sec. 201 makes it unlawful to discharge anything other than stormwater, including pollutants or water carrying pollutants that violate water quality standards, into the County storm drain system, natural surface waters (the definition specifically names the Sacramento River, Cache Creek, Putah Creek, and the Yolo Bypass), or watercourses, except for the exemptions listed in Sec.

202. Illicit connections to the storm drain system are separately prohibited under Sec. 205. The Administrator, the Assistant Director of the Planning, Resources and Public Works Department, may collect inspection fees under Sec. 404 and enforce the Chapter under Sec. 505 through warnings, Notices of Noncompliance that must state the section violated and a correction deadline, or immediate enforcement where there's no grace period. Anyone under an industrial or construction NPDES stormwater permit must also show compliance with that permit before getting a subdivision map, site plan, or building permit approved, per Sec. 503. A violation can trigger both county enforcement and separate federal or state Clean Water Act and Porter-Cologne liability under Sec. 504.