Erosion Control: Altadena vs Downey
How do erosion control rules compare between Altadena, CA and Downey, CA?
Altadena and Downey have similar restriction levels.
Altadena, CA
Los Angeles County
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.
View full Altadena rules →Downey, CA
Los Angeles County
Grading and construction projects in Downey exceeding 1 acre require a Stormwater Pollution Prevention Plan (SWPPP). Erosion control measures must be in place during the rainy season per state and county requirements.
View full Downey rules →Key Facts Comparison
| Fact | Altadena | Downey |
|---|---|---|
| Code Section | LA County Title 26 App. J + CSD 22.306.060.B.3.b | - |
| Rainy Season | Oct 15 – Apr 15 | Oct 1 - Apr 15 BMPs required |
| BMPs Required | Silt fences, fiber rolls, hydroseed | - |
| SWPPP | - | Required for sites >1 acre |
| County | - | LA County grading requirements |
| State | - | CA Construction General Permit |
Highlighted rows indicate differences between cities.
Altadena FAQ
Do I need erosion controls during winter construction in Altadena?
Yes — rainy-season grading (Oct 15 to Apr 15) must implement Public Works–approved BMPs per Altadena CSD 22.306.060.B.3.b.
Downey FAQ
Do I need erosion control for a small project?
Most jurisdictions require erosion control for any ground disturbance over 500 to 1,000 square feet. Check Downey grading permit requirements.
Who inspects erosion controls?
Downey building or public works department inspects during active construction. Federal EPA NPDES permits may also apply for sites over one acre.
Compare other topics
See how Altadena and Downey compare on other ordinance categories.
Want to add a third city?
Use our full comparison tool to compare up to three cities.
Open Comparison Tool