Environmental Rules in Altadena, CA (2026)
4 verified environmental rules for Altadena, California, sourced directly from the municipal code and official government pages.
Verified from official government sources
Stormwater Management
LA County operates under a regional MS4 permit issued by the LA Regional Water Quality Control Board. LA County Code Title 12 prohibits discharging non-stormwater (sediment, chemicals, paint, sewage, washwater) into storm drains.
Altadena Stormwater Rules (LA County NPDES + Title 12)
Some RestrictionsErosion Control
All grading and disturbed sites in Altadena must implement erosion controls under LA County Building Code Title 26 Appendix J and the County's MS4 permit. Rainy-season grading (Oct 15 – Apr 15) requires Best Management Practices approved by Public Works.
Altadena Erosion Control (LA County Public Works)
Some RestrictionsFlood Zones
Most of Altadena is in FEMA Flood Zone X (minimal hazard), but the area along Eaton Wash, the Arroyo Seco tributaries, and post-Eaton Fire burn-scar areas have heightened flood and debris-flow risk. LA County Code Ch. 22.142 (Floodplain Management) applies in mapped Special Flood Hazard Areas.
Altadena Flood Zones (FEMA + LA County Code Ch. 22.142)
Some RestrictionsFEMA Flood Map Service Center (MSC) — About Page
About Flood Map Service Center The FEMA Flood Map Service Center (MSC) is the official public source for flood hazard information produced in support of the National Flood Insurance Program (NFIP). Use the MSC to find your official flood map, access a range of other flood hazard products, and take advantage of tools for better understanding flood risk. FEMA flood maps are continually updated th...
Grading & Drainage
Hillside grading exceeding 2,500 cubic yards cut + fill requires a Conditional Use Permit in Altadena (CSD 22.306.060.B.2.b). Grading during the Oct 15 – Apr 15 rainy season is subject to Public Works erosion-control requirements.
Altadena Grading & Drainage (Altadena CSD + LA County 22.140.240)
Heavy RestrictionsLooking for Los Angeles County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Altadena city rules.
Environmental Rules in Los Angeles County →