Erosion Control: Daly City vs San Mateo
How do erosion control rules compare between Daly City, CA and San Mateo, CA?
San Mateo has fewer restrictions than Daly City.
Daly City, CA
San Mateo County
Erosion and sediment control on Daly City construction sites is required by the Bay Area Municipal Regional Stormwater Permit (Order R2-2015-0049 Provision C.6), the statewide Construction General Permit (Order 2009-0009-DWQ) for projects disturbing 1 acre or more, and the California Building Code Appendix J grading provisions adopted in Title 12.
View full Daly City rules →San Mateo, CA
San Mateo County
San Mateo requires Erosion and Sediment Control Plans for all projects requiring a demolition, grading, or building permit that involve site disturbance. Projects disturbing one acre or more require a state Construction General Permit with SWPPP. The city's hillside areas require particular attention to erosion prevention.
View full San Mateo rules →Key Facts Comparison
| Fact | Daly City | San Mateo |
|---|---|---|
| Wet season | October 1 - April 30 (heightened BMP requirements) | - |
| CGP threshold | 1 acre disturbed (or common plan of development) | - |
| Local authority | MRP Provision C.6 + CBC Appendix J grading | - |
| Required BMPs | Silt fence, wattles, inlet protection, slope stabilization | - |
| SWPPP | Required if CGP applies; signed by QSD | - |
| Required | - | All construction with site disturbance |
| SWPPP Threshold | - | 1+ acres of disturbance |
| Rainy Season | - | October through April — high risk |
| Hillside Areas | - | Elevated erosion concern |
| Public Works | - | 650-522-7300 |
Highlighted rows indicate differences between cities.
Daly City FAQ
Does a small backyard project need erosion control?
Yes - any soil-disturbing work that could send sediment to a gutter or storm drain is subject to MRP construction-site BMPs. The Engineering or Building Division typically requires at minimum a silt fence or fiber roll along the downhill edge and protection at the nearest storm-drain inlet.
When is wet-season erosion control required?
Daly City follows the Bay Area MRP wet-season window of October 1 through April 30. Exposed slopes must be stabilized (mulch, hydroseed, erosion mat, or equivalent) before October 1 each year unless active grading is approved.
Do I need a SWPPP?
Only if your project disturbs 1 acre or more (including phased projects under a common plan of development). Smaller sites still need an erosion-and-sediment-control plan but not a state-filed SWPPP.
San Mateo FAQ
Do I need an erosion control plan in San Mateo?
Yes. All projects with site disturbance requiring a demolition, grading, or building permit must submit an Erosion and Sediment Control Plan.
When is erosion risk highest in San Mateo?
The rainy season from October through April presents the highest erosion risk, especially on the western hillside areas.
What happens if sediment enters the storm drain?
Sediment discharge to storm drains is a violation of the city's NPDES permit and the federal Clean Water Act. State fines can reach $10,000 per day.
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