Los Angeles County, CA Environmental Rules: Erosion Control (2026)
Key Facts
- Planting trigger: cut slopes
- Required for cut slopes over 5 feet high
- Planting trigger: fill slopes
- Required for fill slopes over 3 feet high
- Additional planting (slopes over 15 ft)
- Shrubs (max 10 ft spacing) or trees (max 20 ft spacing)
- Irrigation requirement
- Approved system covering all portions of slope; hose bibs acceptable under 20 ft
- Plan requirement
- Civil engineer or landscape architect required for slopes 20 ft+
- Final approval condition
- Planting must be 'well established and growing'
Summary
All cut and fill slopes in unincorporated LA County must be planted and irrigated to prevent erosion, with taller slopes requiring both ground cover and shrubs or trees at specific spacing: planting must be established before the county grants final grading approval.
J110.1 General.
The faces of cut and fill slopes shall be prepared and maintained to control erosion. This control shall consist of effective planting, erosion control blankets, soil stabilizers, or other means as approved by the Building Official.
J110.3 Planting.
The surface of all cut slopes more than 5 feet (1.5 m) in height and fill slopes more than 3 feet (0.9 m) in height shall be protected against damage from erosion by planting with grass or ground cover plants. Slopes exceeding 15 feet (4.6 m) in vertical height shall also be planted with shrubs, spaced at not to exceed 10 feet (3 m) on center, or trees, spaced at not to exceed 20 feet (6.1 m) on center; or a combination of shrubs and trees at an equivalent spacing, in addition to grass or ground cover plants.
(Ord. 2025-0047 § 80, 81, 2025.)
Full Breakdown
Section J110 of Appendix J (Building Code) requires that cut slopes over 5 feet high and fill slopes over 3 feet high be covered with grass or ground cover. Slopes over 15 feet must also include shrubs spaced no more than 10 feet apart or trees no more than 20 feet apart. An approved irrigation system must cover all portions of the slope; hose bibs are acceptable for slopes under 20 feet. Planting and irrigation plans for slopes 20 feet or taller must be prepared and signed by a civil engineer or landscape architect. The county will not grant final grading approval until planting is 'well established and growing' and an effective rodent control program is in place.
Violations & Fines
Failure to install required planting and irrigation prevents final grading approval and release of security deposits. Non-compliance with NPDES/SWPPP stormwater requirements can result in daily penalties of $50–$500 per day. The county may enter the property and install required erosion controls at the owner's expense.
Frequently Asked Questions
Do I have to plant vegetation on any graded slope on my property?
Who designs the planting plan for a large graded slope?
Can I use erosion control blankets instead of plants?
Sources & Official References
Other rules in Los Angeles County
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