Environmental Rules in Sonoma County, CA (2026)
4 county-level rules, plus city-specific rules for 2 cities in Sonoma County, California.
Verified from official government sources
Stormwater Management
Sonoma County prohibits discharging anything but stormwater into the county's stormwater system, requiring construction sites, parking lots, and businesses to control pollutants and follow best management practices under Chapter 11A.
Sonoma County Stormwater Discharge Rules
Some RestrictionsSonoma County Code § 11A-5
The release of non-stormwater discharges to the county's stormwater system is prohibited.(b)The following discharges are exempt from the prohibition set forth in subsection (a) of this section:(1)Any discharge in compliance with a National Pollution Discharge Elimination System (NPDES) permit issued to the discharger and administered by the state of California under the authority of the United ...
Erosion Control
Unincorporated Sonoma County requires a construction grading permit before any cut, fill, or land-disturbing work over minor thresholds, plus a separate drainage permit for new or modified drainage facilities, under Chapter 11 of the county code.
Sonoma County Grading & Drainage Permits
Some RestrictionsSonoma County Code § 11.04.010(A)
A construction grading permit shall be required prior to commencing any construction grading or related work, including preparatory land clearing, vegetation removal, or other ground disturbance, except where exempted from permit requirements by Subsection C. A separate construction grading permit shall be required for each site.B.Designation and performance. Construction grading shall be desig...
Flood Zones
Unincorporated Sonoma County requires a floodplain development permit and elevates new residential construction at least 12 inches above the base flood elevation inside FEMA-mapped special flood hazard areas.
Sonoma County Flood Zone Building Rules
Some RestrictionsSonoma County Code § 7B-11(a)
New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated above the base flood elevation at least twelve inches (12″).
Flood Elevation Requirements
In unincorporated Sonoma County, new homes and substantial remodels inside a mapped special flood hazard area must raise the lowest floor at least 12 inches above the base flood elevation: a local freeboard buffer stacked on top of FEMA's bare minimum.
Sonoma County Base Flood Elevation Rules
Some RestrictionsSonoma County Code § 7B-11(a)
Residential Construction. New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated above the base flood elevation at least twelve inches (12″).
Environmental Rules by City in Sonoma County
2 cities in Sonoma County have their own environmental rules rules. Each link goes to that city's dedicated page with code citations.
All Sonoma County ordinances
See every category we cover for Sonoma County: parking, noise, fences, fires, animals, pools, and more.
Sonoma County Ordinance Hub →