Stormwater Management: Castro Valley vs Hayward
How do stormwater management rules compare between Castro Valley, CA and Hayward, CA?
Castro Valley and Hayward have similar restriction levels.
Castro Valley, CA
Alameda County
Alameda County complies with SF Bay Regional Water Board MRP 3.0. Projects disturbing 10,000 sf or more must incorporate Low Impact Development treatment per Provision C.3.
View full Castro Valley rules →Hayward, CA
Alameda County
Hayward enforces the Countywide C.3 stormwater requirements for projects creating 2,500 square feet of impervious area. Illicit discharges to storm drains are prohibited under the NPDES MS4 permit.
View full Hayward rules →Key Facts Comparison
| Fact | Castro Valley | Hayward |
|---|---|---|
| Permit | MRP 3.0 (SF Bay Water Board) | - |
| C.3 threshold | 10,000 sf impervious | 2,500 sf impervious |
| Single-family | 2,500 sf reduced threshold | - |
| Hydromodification | Over 1 acre | - |
| Local agency | Alameda Clean Water Program | - |
| Full C.3 | - | Over 10,000 sf |
| Wet season | - | Oct 1 - Apr 30 |
| Illicit discharge | - | Prohibited NPDES |
| MRP Permit | - | SF Bay RWQCB |
Highlighted rows indicate differences between cities.
Castro Valley FAQ
Do I need stormwater treatment for my home addition?
Only if the project creates or replaces 2,500 square feet or more of impervious surface on single-family lots. Most small additions fall below this threshold but still must avoid illicit discharges.
Can I wash my car in the driveway?
Soapy runoff to storm drains is an illicit discharge. Use commercial car washes that recycle water or wash on gravel or lawn where runoff soaks in rather than entering the street.
Hayward FAQ
Can I drain my pool to the street?
Only after dechlorinating and at a slow rate to prevent erosion; chlorinated water is an illicit discharge.
Do small remodels need stormwater features?
Projects under 2,500 sf of new impervious area typically do not trigger C.3, but erosion controls still apply.
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