Stormwater Management: Daly City vs Redwood City
How do stormwater management rules compare between Daly City, CA and Redwood City, CA?
Redwood City has fewer restrictions than Daly City.
Daly City, CA
San Mateo County
Daly City is a co-permittee under the San Francisco Bay Regional Water Quality Control Board Municipal Regional Stormwater NPDES Permit (Order R2-2015-0049, as amended by R2-2019-0049) and a member of the San Mateo Countywide Water Pollution Prevention Program (SMCWPPP / Flows To Bay). Discharges of anything other than rainwater into the storm drain system are prohibited.
View full Daly City rules →Redwood City, CA
San Mateo County
Unincorporated San Mateo County is a permittee under the San Francisco Bay Area Municipal Regional Stormwater Permit (MRP 3.0, Order R2-2022-0018) which imposes NPDES Phase I stormwater requirements. Projects creating/replacing 2,500+ sq ft of impervious surface trigger C.3 post-construction stormwater treatment requirements (LID, biofiltration). Illicit discharges to storm drains are prohibited. Construction sites disturbing 1+ acres require SWPPPs and monthly wet-season inspections.
View full Redwood City rules →Key Facts Comparison
| Fact | Daly City | Redwood City |
|---|---|---|
| NPDES permit | MRP Order R2-2015-0049 (amended 2019) | - |
| Countywide program | SMCWPPP / Flows To Bay (20 cities) | - |
| C.3 threshold | 10,000 sq ft impervious (2,500 sq ft special uses) | - |
| Construction permit | Statewide CGP if >=1 acre disturbed | - |
| Receiving waters | San Francisco Bay & Pacific Ocean | - |
| Permit | - | MRP 3.0 R2-2022-0018 |
| C.3 Trigger | - | 2,500+ sq ft impervious |
| Treatment | - | LID / biofiltration |
| Construction | - | 1+ acre needs SWPPP |
| Discharge | - | Zero pollutants allowed |
Highlighted rows indicate differences between cities.
Daly City FAQ
Can I wash my car in my driveway?
Wash water that runs to the street storm drain is a prohibited discharge under the MRP and SMCWPPP rules. Use a commercial car wash that recycles wash water, or wash on a vegetated/gravel area where soapy water soaks in instead of running to the gutter.
Do small home additions need stormwater treatment?
Residential projects that create or replace less than 10,000 sq ft of impervious surface are generally below the C.3 Regulated Project threshold, but construction-site BMPs (silt fence, covered material storage, no concrete washout into the gutter) are still required by the MRP and by Daly City's grading/erosion-control rules.
Can I drain my pool to the street?
Chlorinated, copper-treated, or salt pool water is a prohibited discharge. Dechlorinate, then discharge slowly to landscape, or coordinate with North San Mateo County Sanitation District for sanitary-sewer discharge — never to a storm drain inlet or gutter.
Redwood City FAQ
Does adding a patio or new driveway trigger stormwater treatment?
If your project creates or replaces 2,500 or more square feet of impervious surface (cumulative over 5 years), yes — you trigger Provision C.3 and must implement on-site stormwater treatment (typically a bioretention area sized to the project). Permeable pavers receive 50% credit. Below 2,500 sq ft, source control and site design still apply but full treatment is not required.
How do I report oil or paint being dumped down a storm drain?
Call the San Mateo County Stormwater Pollution Hotline: (650) 599-1420, or report online at smcsustainability.org/report-pollution. For immediate hazards (large spill, chemicals reaching a creek) call 911. Illicit discharges carry federal Clean Water Act penalties.
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