Mendocino County, CA Environmental Rules: Stormwater Management (2026)
Key Facts
- Governing chapter
- Ch. 16.30, adopted 2013 (Ord. 4313)
- Applies to
- Unincorporated urban boundary areas
- Max fine per violation
- $1,000
- Enforcement lead
- Director, Planning and Building Services
- Enforcement approach
- Education first, then Ch. 8.75 nuisance action
- Exempt
- Non-urban timber and agricultural operations
Summary
The Stormwater Runoff Pollution Prevention Procedure bans illicit discharges and illegal connections into the County storm drain system, requires Best Management Practices on construction sites, and fines violators up to $1,000 per violation plus nuisance enforcement.
No person shall discharge or cause to be discharged into the County storm drainage system or watercourses any materials, including pollutants or waters containing any pollutants that cause or contribute to a violation of applicable water quality standards, other than storm water, to the maximum extent practicable. The commencement, conduct or continuance of any other discharge to the storm drainage system and watercourses is prohibited, except for the following.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 75).
Full Breakdown
from developed and undeveloped land in the unincorporated urban boundary areas mapped by the Department of Planning and Building Services, per Sec. 030. Sec. 040 prohibits discharging anything but storm water into the system or watercourses to the maximum extent practicable, while listing authorized non-storm-water discharges such as potable line flushing, rising groundwater, dechlorinated pool water and incidental landscape irrigation runoff when properly managed. Sec. 050 separately bans illicit connections, meaning any drain or pipe, including from indoor sinks or commercial and industrial premises, that lets sewage, wastewater or wash water reach the storm drain system without County approval.
Sec. 070 requires anyone conducting construction or grading, or operating a commercial or industrial facility, to implement Best Management Practices such as sediment traps, stabilized construction exits, erosion control on slopes, and off-site vehicle washing, obtainable from Planning and Building Services, the Department of Transportation, or the County Water Agency. Projects disturbing less than an acre must instead show compliance with the California Green Building Standards Code's stormwater provisions under Sec. 030(C). Sec. 031 puts the Director of Planning and Building Services in charge of administering the Chapter, and Sec.
150 states enforcement leads with education and a corrective action plan before escalating. Timber and agricultural operations are exempt from the Chapter under Sec. 030(D), except for illicit discharges that reach the storm system.
Violations & Fines
Sec. 16.30.160 makes it unlawful to violate any provision of Chapter 16.30, including failing to implement a corrective action plan, punishable by a fine of up to $1,000 per violation. Any violating condition is also declared a public nuisance and a misdemeanor, enforced under Chapter 8.75's Uniform Nuisance and Abatement Procedure, and a violator may separately face civil or criminal penalties under the federal Clean Water Act or the state Porter-Cologne Act, with written notice of that potential liability required.
Frequently Asked Questions
What can't I discharge into a Mendocino County storm drain?
What happens if a construction site violates the stormwater rules?
Are farms and timber operations covered by the stormwater ordinance?
Sources & Official References
Other rules in Mendocino County
California rules heatmap·Compare Mendocino County to another location·View the California environmental rules overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.