Stormwater Management: Rohnert Park vs Sonoma
How do stormwater management rules compare between Rohnert Park, CA and Sonoma, CA?
Rohnert Park and Sonoma have similar restriction levels.
Rohnert Park, CA
Sonoma County
Sonoma County operates under two separate Municipal Separate Storm Sewer System (MS4) NPDES permits - one issued by the North Coast Regional Water Quality Control Board for the Russian River basin and one by the San Francisco Bay Regional Water Quality Control Board for southern Sonoma County. Chapter 11 of the Sonoma County Code prohibits discharge of any pollutant (including muddy construction runoff) to the storm-drain system or waters of the state. Development and redevelopment projects must implement Low-Impact Development (LID) post-construction stormwater controls.
View full Rohnert Park rules →Sonoma, CA
Sonoma County
Sonoma operates under a State NPDES Phase II MS4 permit and bans non-stormwater discharges into the city's storm drains, which flow untreated to Nathanson, Sonoma, and Fryer Creeks.
View full Sonoma rules →Key Facts Comparison
| Fact | Rohnert Park | Sonoma |
|---|---|---|
| Local Code | Sonoma County Code Chapter 11 (Construction Grading and Drainage) | - |
| Federal Authority | Clean Water Act Section 402 (NPDES) | - |
| State Authority | Porter-Cologne Water Code Sections 13000+ | - |
| MS4 Permits | North Coast RWQCB + San Francisco Bay RWQCB | - |
| Required Controls | LID post-construction BMPs (bioretention, swales, etc.) | - |
| C.3 Threshold (SFB) | >= 10,000 sq ft impervious creation/replacement | - |
| Construction Plan Form | Permit Sonoma GRD-011 - Erosion Prevention & Sediment Control Notes | - |
| Civil Liability | Up to $10,000/day per violation (Water Code 13350) | - |
| Code section | - | SMC Ch. 13.32 |
| Permit | - | State NPDES Phase II Small MS4 |
| SWCP threshold | - | 5,000 sq ft impervious |
| Mitigation threshold | - | 2,500 sq ft impervious |
| Receiving waters | - | Nathanson, Sonoma, Fryer Creeks |
Highlighted rows indicate differences between cities.
Rohnert Park FAQ
Can I discharge pool water or wash water to a Sonoma County storm drain?
Generally no. Only specifically exempted clean discharges (e.g., uncontaminated groundwater, dechlorinated and pH-neutralized pool water meeting discharge limits) are allowed under Sonoma County Code Chapter 11 and the County's MS4 permits. Soaps, detergents, paint wash, concrete slurry, and chlorinated pool water are prohibited from entering storm drains.
What stormwater controls do I need for a new development in Sonoma County?
Construction-phase Erosion and Sediment Control Plans per Permit Sonoma GRD-011, plus Low-Impact Development (LID) post-construction BMPs. In the Bay Area AQMD portion of the county, C.3 Regulated Projects (10,000 sq ft or more of impervious surface) require sized treatment and hydromodification controls under the SFB MS4 permit.
Is my small project really subject to stormwater rules?
Yes - even projects under 1 acre that are exempt from the State Construction General Permit are still subject to Sonoma County Code Chapter 11's prohibition on polluted runoff. BMPs must be implemented year-round and significantly increased during the wet season (October 15 - May 15).
Sonoma FAQ
Can I wash my car in the driveway?
Residential car washing is generally allowed, but soapy water flowing into the gutter is an illicit discharge under SMC 13.32. The city recommends washing on grass or at a commercial car wash that routes wash water to the sanitary sewer.
Do I need a Stormwater Control Plan for a small remodel?
Only if the project creates or replaces 5,000 sq ft or more of impervious surface. Smaller projects creating 2,500+ sq ft must still mitigate downstream impacts per the NPDES permit.
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