Sonoma County, CA Environmental Rules: Stormwater Management (2026)
Key Facts
- Governing chapter
- Chapter 11A
- Violation classification
- Misdemeanor (Sec. 11A-10)
- Applies to
- Unincorporated county only
- Enforced by
- Permit & Resource Mgmt Dept, etc.
- Adopted
- Ord. No. 5819 (2008)
Summary
Sonoma County prohibits discharging anything but stormwater into the county's stormwater system, requiring construction sites, parking lots, and businesses to control pollutants and follow best management practices under Chapter 11A.
The release of non-stormwater discharges to the county's stormwater system is prohibited.(b)The following discharges are exempt from the prohibition set forth in subsection (a) of this section:(1)Any discharge in compliance with a National Pollution Discharge Elimination System (NPDES) permit issued to the discharger and administered by the state of California under the authority of the United States Environmental Protection Agency.(2)Discharges from the following activities will not be considered a prohibited discharge to the county's stormwater system when properly managed: flushing of potable water from potable water lines and other discharges from potable water sources, landscape irrigation and lawn watering, irrigation water, diverted stream flows, rising groundwaters, uncontaminated groundwater infiltration to storm drains, uncontaminated pumped groundwater, foundation and footing drains, water from crawlspace pumps, air conditioning condensation, springs, runoff from individual residential car washing, flows from riparian habitats and wetlands, dechlorinated swimming pool discharges or flows from emergency firefighting, and any other flows necessary for implementing BMPs directed or approved by the administrative authority. (Ord. No. 5819, § 6, 12-9-2008.)
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 64 Update 2).
Full Breakdown
Chapter 11A-Stormwater Quality bans any discharge to the county's stormwater system that isn't composed entirely of stormwater, covering everything from dumped waste and construction debris to unmanaged parking-lot runoff. The administrative authority -- the Permit and Resource Management Department, Transportation and Public Works, Health Services, Emergency Services, or the Agricultural Commissioner -- enforces the rule, can order violators to cease and desist, and can also require a stormwater pollution prevention plan and BMPs from businesses whose activities could add pollutants. This applies within unincorporated Sonoma County, not the incorporated cities inside it, each of which runs its own stormwater program.
Violations & Fines
Violating Chapter 11A is a misdemeanor under Sec. 11A-10; the county can also pursue civil liability up to its own NPDES-permit fine exposure, cease-and-desist orders, and public nuisance abatement under Sec. 11A-17.
Frequently Asked Questions
Does this cover stormwater in Santa Rosa or other cities?
What counts as a prohibited discharge?
Sources & Official References
Other rules in Sonoma County
California rules heatmap·Compare Sonoma County to another location·View the California environmental rules overview
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