Environmental Rules in Mendocino County, CA (2026)
4 rules for unincorporated Mendocino County, California.
Verified from official government sources
Stormwater Management
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.
Mendocino County Stormwater Runoff Rules
Some RestrictionsMendocino County Code Sec. 16.30.040 (Prohibition of Illicit Discharges)
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 drai...
Erosion Control
Anyone grading in unincorporated Mendocino County must control erosion on cut and fill slopes, typically with planting installed before the county signs off on final approval, and the Building Official can also require check dams, cribbing, or riprap. In the Coastal Zone, grading over two cubic yards counts as "development" and needs a Coastal Development Permit on top of the standard erosion-control rule.
Mendocino County Grading Erosion Control Rules
Some RestrictionsMendocino County Code § 18.70.130 (Erosion Control)
(A)Slopes. The faces of cut and fill slopes shall be prepared and maintained to control against erosion. This control may consist of effective planting. The protection for the slopes shall be installed as soon as practicable and prior to calling for a final approval. Where cut slopes are not subject to erosion due to the erosion-resistant character of the materials, such protection may be omitt...
Flood Zones
Any construction or development in a Mendocino County special flood hazard area needs a development permit from the Floodplain Administrator, based on FEMA's Flood Insurance Study and rate maps for the unincorporated county.
Mendocino County Floodplain Development Permit Rules
Significant RestrictionsMendocino County Code Sec. 22.17.205 (Lands to Which this Ordinance Applies) and Sec. 22.17.305 (Establishment of Development Permit)
This ordinance shall apply to all areas of special flood hazards within the unincorporated lands of Mendocino County... A development permit shall be obtained before any construction or other development begins within any area of special flood hazard established in Section 22.17.210.
Flood Elevation Requirements
New or substantially improved residential buildings in a Mendocino County flood hazard area must have their lowest floor at least one foot above the base flood elevation, certified by a licensed engineer or surveyor after construction.
Mendocino County Flood Elevation Freeboard Rule
Some RestrictionsMendocino County Code Sec. 22.17.405(A)(3)(a) (Standards of Construction, Elevation and flood-proofing)
Residential construction, new or substantial improvement, shall have the lowest floor, including basement: (i) In an AO zone, elevated to a height above the highest adjacent grade of not less than the depth number specified in feet (mm) on the FIRM plus one (1) foot (305mm), or not less than three (3) feet (915 mm) if a depth number is not specified. (ii) In all other Zones, elevated at least o...
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