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Alameda County, CA Environmental Rules: Erosion Control (2026)

Heavy Restrictions

Verified 1 month ago|Source: Construction General Permit →

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Key Facts

Wet season: October 1 to April 30
Permit trigger: 1 acre disturbance
Plan required: SWPPP with QSD
Required BMPs: Silt fences, wattles, inlets
Penalty: Up to 10,000 per day

City-specific rules exist: Oakland, Berkeley, Hayward, Fremont, San Leandro, and Livermore have their own erosion control rules that differ from Alameda County's county-level regulations. If you live in one of those cities, check the city-specific page instead.

Summary

Alameda County requires erosion control during the rainy season (October 1 to April 30). Projects over 1 acre need a Construction General Permit and a SWPPP.

Full Breakdown

Erosion control in Alameda County is enforced by the county Public Works Agency and individual cities under the MRP 3.0 and the State Construction General Permit. Active construction sites must install Best Management Practices (BMPs) such as silt fences, fiber rolls, straw wattles, inlet protection, and stabilized construction entrances. During the October-April wet season, all disturbed soil must be stabilized within specific timeframes. Hillside grading in Castro Valley, Sunol, and unincorporated canyons faces stricter requirements due to erodible soils and steep slopes. Projects disturbing 1 acre or more require coverage under the State Water Board Construction General Permit (Order 2022-0057-DWQ), a Qualified SWPPP Developer, and a site-specific SWPPP. Violations can trigger stop-work orders and penalties up to 10,000 dollars per day per the Porter-Cologne Water Quality Control Act.

Frequently Asked Questions

Do I need a SWPPP for a small home project?

Only if you disturb 1 acre or more, which is unusual for single-family projects. Smaller projects still need basic erosion control BMPs during the wet season.

What BMPs work best on my hillside lot?

Combine silt fences or fiber rolls at the downslope perimeter, straw wattles along contours, and rapid revegetation or hydroseeding of disturbed areas before October 1.

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Alameda County, CA Environmental Rules: Erosion Control (2026)

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