Clark County, NV Environmental Rules: Grading & Drainage (2026)

The Clark County Building Code (Title 22) and Unified Development Code (Title 30) regulate grading, drainage, and site preparation in unincorporated areas. Grading permits are generally required when excavation or fill exceeds 50 cubic yards, slopes exceed 5 feet vertical, or the project lies in a flood hazard area. Permit applications require a site plan, grading plan, drainage calculations, and soils report sealed by a Nevada-licensed engineer. Projects over 5 acres typically require a full drainage study following the CCRFCD Hydrologic Criteria and Drainage Design Manual (HCDDM) demonstrating that post-development peak flows do not exceed pre-development flows (often requiring onsite detention basins). Site drainage must not discharge more than the 10-year historic flow onto neighboring properties. Desert soils in the Las Vegas Valley include collapsible soils and gypsum-rich caliche that require specialized foundation engineering. Projects adjacent to CCRFCD regional channels must coordinate easements and encroachment. Any work in a Waters of the United States also triggers USACE Section 404 permits and NDEP Section 401 water quality certification.