Environmental Rules in Marin County, CA (2026)
7 county-level rules, plus city-specific rules for 1 city in Marin County, California.
Verified from official government sources
Stormwater Management
Marin County Code of Ordinances § 23.18.060 bans discharging anything but stormwater into a county storm drain or an area of special biological significance, and every construction and redevelopment project in the unincorporated area must install best management practices under §§ 23.18.093 and 23.18.094 to keep sediment and pollutants out of the drainage system.
Marin County Stormwater Runoff Discharge Ban
Significant RestrictionsMarin County Code of Ordinances § 23.18.060
The discharge of material other than stormwater to a county storm drain or to an ASBS is prohibited. All discharges of material other than stormwater must be in compliance with a NPDES permit issued for the discharge.
Erosion Control
Marin County requires an approved erosion and sediment control plan for any project with a grading permit, or any building permit the County finds could cause significant erosion, under Section 24.04.625 of the County Code. Grading is barred outright between October 15 and April 15 without the Public Works Agency's prior approval.
Marin County Erosion and Sediment Control Rule
Significant RestrictionsMarin County Code § 24.04.625 (Erosion and Sediment Control)
(a)All disturbed surfaces, including, but not limited to, cut and fill slopes, building pads, driveways and areas cleared of vegetation, shall be protected against erosion and sediment discharges by measures that the agency determines to be appropriate to the site, phase of construction and time of year.(b)When required by the phase II stormwater permit or by the agency, a project shall have an...
Coastal Development
Marin County's coastal areas are regulated by the Local Coastal Program (LCP) Implementation Plan, codified in Title 20 of the Marin County Code. Development within the Coastal Zone, including West Marin and Bay shoreline, requires a Coastal Permit. BCDC also regulates within 100 feet of the Bay shoreline.
Marin County Coastal and Shoreline Rules
Some RestrictionsCalifornia Coastal Commission - Coastal Zone Boundary Map
ries: The original 1977 Coastal Zone Boundary maps were mylar (drafting film) copies of 161 USGS 7.5 minute topographic quadrangles with an inked boundary added. This digital version of the boundary was developed to provide a georeferenced, attributed (to explain the basis of the mapped Coastal Zone), cadastral (parcel-based) depiction of the adopted Coastal Zone Boundary for the planning and r...
Flood Zones
New construction and substantial improvements within Marin County's mapped special flood hazard areas must have the lowest floor built at or above the base flood elevation, certified after completion by a registered civil engineer or licensed land surveyor. Section 23.09.034 sets that standard, and the Department of Public Works reviews every permit application in a flood-prone area first.
Marin County Floodplain Development Standards
Significant RestrictionsMarin County Code of Ordinances § 23.09.034(c)(1)
New construction and substantial improvement of any structure shall have the lowest floor, including basement, elevated to or above the base flood elevation. Nonresidential structures may meet the standards in subparagraph (3) of subsection (c) of this section. Upon completion of the structure, the elevation of the lowest floor, including basement, shall be certified by a registered civil engin...
Boat Dock Permits
Marin County requires a written encroachment permit from the Department of Public Works before anyone installs a pier, catwalk, dock, float, or gangway on county land bordering Gallinas Creek, or on flood-control district land along Corte Madera Creek. Working without one doubles the fee, and only property owners whose land abuts the waterway ordinarily qualify.
Marin County Boat Dock Permits: Two Creeks
Some RestrictionsMarin County Code of Ordinances § 11.24.010
The director of public works may, upon receipt of an application therefor and payment of an application fee as established in the current "Resolution of the Marin County Board of Supervisors Establishing Fees for Permits Administered by the Department of Public Works," issue written permits authorizing the permittee to do any acts within or upon the lands of the county adjacent to Gallinas Cree...
Vehicle Idling Restrictions
Marin County caps construction-equipment idling at five minutes on projects that trigger environmental review. Section 22.20.040(C)(6) of the Development Code tells contractors to shut equipment off when it's not in use or hold idling to five minutes, tracking the state's Airborne Toxics Control Measure, and requires idling-limit signage at every site access point.
Marin County 5-Minute Construction Idling Limit
Some RestrictionsMarin County Development Code § 22.20.040(C)(6)
C.Dust and Emission Control. The following dust and emission control measures shall apply to projects involving ground disturbance that are subject to environmental review:...6.Idling times shall be minimized either by shutting equipment off when not in use or reducing the maximum idling time to five minutes (as required by the California Airborne Toxics Control Measure Title 13, Section 2485 o...
Flood Elevation Requirements
Any new construction or substantial improvement in Marin County's mapped special flood hazard areas must have its lowest floor elevated to or above the base flood elevation, per Marin County Code of Ordinances § 23.09.034. The Department of Public Works, acting as floodplain administrator, reviews every permit in flood-prone unincorporated areas before construction begins.
Marin County Base Flood Elevation Standard
Some RestrictionsMarin County Code of Ordinances § 23.09.034(c)(1)
(c)Elevation and Floodproofing.(1)New construction and substantial improvement of any structure shall have the lowest floor, including basement, elevated to or above the base flood elevation. Nonresidential structures may meet the standards in subparagraph (3) of subsection (c) of this section. Upon completion of the structure, the elevation of the lowest floor, including basement, shall be cer...
Environmental Rules by City in Marin County
1 cities in Marin County have their own environmental rules rules. Each link goes to that city's dedicated page with code citations.
All Marin County ordinances
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