Santa Clara County, CA Environmental Rules: Erosion Control (2026)

Division C12 and Appendix J of the California Building Code, as adopted in Title B of the County Code, govern grading permits. Any grading movement of 50 cubic yards or more, creation of a cut or fill over 3 feet in height, or disturbance of 5000 square feet or more requires a grading permit from the Land Development Engineering section of the County Department of Planning and Development. A Geotechnical Report is required for work on slopes over 10 percent. Applicants must submit an Erosion and Sediment Control Plan identifying BMPs such as silt fences, fiber rolls, erosion control blankets, stabilized construction entrances, and sediment basins. On hillside lots defined in HS combining districts, grading is prohibited during the winter rainy season from October 15 through April 15 unless winterization measures are in place and approved. Construction sites over 1 acre must also obtain coverage under the state Construction General Permit Order 2022-0057-DWQ and file a Stormwater Pollution Prevention Plan. The county inspects erosion controls weekly during rainy season and can issue stop work orders and administrative penalties up to 5000 dollars per day. Unpermitted grading on hillside lots near Lexington Reservoir, Uvas, and the east foothills has generated major enforcement actions in recent years.