Riverside County, CA Environmental Rules: Grading & Drainage (2026)

Earth movement in unincorporated Riverside County is governed by Ord. 457, which is based on the California Building Code Appendix J. A grading permit is required when a project exceeds 50 cubic yards on a single lot, involves cuts over 5 feet or fill over 3 feet, alters existing drainage patterns, or occurs on slopes steeper than 3:1 (horizontal:vertical). Engineered grading (requiring a civil engineer's plans and soils report) is required for projects over 500 cubic yards or in landslide-prone areas. Ord. 458 (Drainage) requires that drainage from developed sites be conveyed to an adequate outlet (existing drainage course or County-approved storm drain) and that new development not cause increased peak flows or erosion downstream. Under Civil Code §§832 and 1038, and Keys v. Romley (1966) case law, upslope property owners cannot increase or concentrate natural drainage onto downslope parcels; redirecting gutters, French drains, or driveway runoff to a neighbor's yard is actionable in civil court in addition to being a potential code violation. Grading in fault hazard zones (Ord. 547) or near blue-line streams requires additional review, and any work in a Waters of the State or USACE jurisdictional waterway requires 401/404 permits and a 1602 Streambed Alteration Agreement from CDFW.