Mendocino County, CA Environmental Rules: Erosion Control (2026)
Key Facts
- Governing section
- Mendocino County Code § 18.70.130
- Coastal zone development trigger
- >2 cubic yards graded
- Coastal permit required
- Coastal Development Permit, § 20.532.010
- Cross-referenced coastal chapters
- Ch. 20.492, Ch. 16.30
- Engineered grading threshold
- 5,000 cubic yards
Summary
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.
(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 omitted.(B)Other Devices. Where necessary, check dams, cribbing, riprap or other devices or methods shall be employed to control erosion and provide safety.
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
Under Sec. 130, cut and fill slope faces from a permitted grading project must be prepared and maintained against erosion, generally through effective planting installed as soon as practicable and before the county grants final approval; slopes made of erosion-resistant material can skip this if the Building Official agrees, and check dams, cribbing, or riprap can be required wherever necessary. A grading permit is required for excavation or fill above small thresholds set in Sec. 5:1, or fills exceeding one foot on slopes flatter than 5:1; projects moving more than 5,000 cubic yards are designated "engineered grading" under Sec.
060(C) and require soils engineering and engineering geology reports. 150(B) ties erosion control directly to project sign-off: final approval is withheld until all drainage facilities, their protective devices, and erosion-control measures are complete and the required as-built reports are submitted. In the county's Coastal Zone, Sec. 027 treats grading moving more than two cubic yards of material as "development" under the Mendocino County Coastal Zoning Code, which Sec. 010 requires to secure a Coastal Development Permit, subject to limited exemptions in Sec. 30 (Stormwater Runoff Pollution Prevention Procedure).
Violations & Fines
If an existing excavation, embankment, or fill becomes a hazard to life, limb, or property, or endangers a public way or drainage channel, Sec. 18.70.040 lets the Building Official order the responsible owner in writing to repair or eliminate it within a specified period. Final grading approval is withheld under Sec. 18.70.150 until erosion-control measures, drainage facilities, and completion reports are in place, and grading without the required permit or coastal development permit exposes the property to Title 18's general permit-violation fee structure.
Frequently Asked Questions
Do I need erosion control if I'm grading my property in Mendocino County?
Does erosion control work differently in Mendocino County's Coastal Zone?
What happens if my finished grading starts eroding later?
Sources & Official References
Other rules in Mendocino County
California rules heatmap·Compare Mendocino County to another location·View the California environmental rules overview
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