Costa Mesa, CA Environmental Rules: Grading & Drainage (2026)

Costa Mesa has adopted Article 8 of Title 7 of the Codified Ordinances of the County of Orange, including the Grading Manual, in its entirety with specific local modifications. A grading permit is required before any grading, excavation, or filling operations begin, except for certain exempt activities. Exempt activities include fills less than one foot deep placed on natural grade with slopes less steep than 5:1 that do not exceed 50 cubic yards and do not obstruct a drainage course, and landscape planter fills less than three feet deep under 50 cubic yards. All grading must be designed to direct drainage away from buildings and toward approved drainage facilities. Property owners may not alter grades in a way that causes water to flow onto neighboring lots. Each landscape plan must address functional aspects of grading, drainage, minimal runoff, and erosion prevention. Construction projects requiring discretionary land use approval, grading permits, building permits, or non-residential plumbing permits are also subject to water quality regulations. Grading plans must be prepared by a licensed civil engineer and may require soils reports for larger projects.