Environmental Rules in Ontario, CA (2026)
4 verified environmental rules for Ontario, California, sourced directly from the municipal code and official government pages.
Verified from official government sources
Stormwater Management
Ontario enforces the Santa Ana Regional MS4 permit requiring erosion control, trash capture, and Low Impact Development for projects over 5,000 square feet, with enforcement through OMC Chapter 5 Article VI.
Ontario Stormwater and Runoff Rules
Heavy RestrictionsErosion Control
Ontario requires active erosion control on all graded sites year-round under OMC Chapter 5 Article VI, with enhanced Best Management Practices from October 1 through April 30 during the rainy season.
Ontario Erosion and Sediment Control
Heavy RestrictionsFlood Zones
Most of Ontario is in FEMA Zone X (minimal hazard), but areas near Cucamonga Creek and the Chino Basin are in Zone AE and require lowest floors 1 foot above Base Flood Elevation under OMC Chapter 28.
Ontario FEMA Flood Zone Rules
Some RestrictionsGrading & Drainage
Ontario requires a grading permit under OMC Title 6 for any earthwork over 50 cubic yards or cuts and fills deeper than 3 feet, with geotechnical review for projects over 500 cubic yards.
Ontario Grading and Drainage Permits
Heavy RestrictionsLooking for San Bernardino County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Ontario city rules.
Environmental Rules in San Bernardino County →