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

San Joaquin County Public Works issues grading permits under the Development Title and CBC Appendix J. Permits required for: excavation or fill exceeding 50 cubic yards; cuts over 5 feet in height or fills over 3 feet; any grading within a FEMA Special Flood Hazard Area (Zones A, AE, AO, AH — substantial portions of the county given its Central Valley and Delta position); any work within 10 feet of a property line where drainage could be altered; and any grading on slopes greater than 3:1. Plans must include: existing and proposed contours, cross-sections, drainage calculations demonstrating that discharge volumes and velocities do not increase onto neighboring parcels (California Civil Code §1714 + common-law "reasonable use" doctrine), erosion and sediment control BMPs, and geotechnical report for significant cuts/fills. Retaining walls over 4 feet (measured from bottom of footing) require separate building permits with engineered plans. In FEMA SFHAs, finished-floor elevations must comply with the National Flood Insurance Program (NFIP) — generally 1 foot of freeboard above Base Flood Elevation. Grading within the Delta Primary Zone or within 30 feet of a state levee requires Central Valley Flood Protection Board encroachment approval. Improper drainage onto a neighbor's property is actionable civilly (nuisance/trespass) and by county code enforcement.