Environmental Rules in Snohomish County, WA (2026)
6 county-level rules, plus city-specific rules for 4 cities in Snohomish County, Washington.
Verified from official government sources
Stormwater Management
Unincorporated Snohomish County requires a stormwater site plan and drainage review once a project adds 2,000 square feet of new or replaced hard surface, or disturbs 7,000 square feet of land, under SCC chapter 30.63A. Discharges that violate water quality standards draw monetary penalties up to $3,000 for residents and $6,000 for businesses under chapter 7.53.
Stormwater Drainage Rules in Snohomish County
Some RestrictionsSCC 30.63A.300(2)
Unless an exception under SCC 30.63A.210 applies, new development projects shall comply with minimum requirements 1 through 5 (SCC 30.63A.400 through 30.63A.525) for the new and replaced hard surfaces and the land disturbed if the new development will: (a) Result in or add 2,000 square feet or greater of new, replaced or new plus replaced hard surface area; or (b) Cause land disturbing activity...
Erosion Control
Unincorporated Snohomish County requires every new development and redevelopment project, regardless of size, to control soil erosion and sediment discharge into receiving waters through a Stormwater Pollution Prevention Plan (SWPPP) approved before construction begins.
Erosion & Sediment Control in Snohomish County
Some RestrictionsSCC 30.63A.450
(2) Applicants for all new development and redevelopment projects of any size shall be responsible for preventing soil erosion and the discharge of sediment and pollutants into receiving waters. A SWPPP must be submitted as part of the stormwater site plan. The SWPPP shall be implemented prior to initial soil disturbance through final stabilization. ... (4) All new development and redevelopment...
Flood Zones
Any development inside a mapped special flood hazard area in unincorporated Snohomish County needs a flood hazard permit before work starts, under SCC 30.43C.020, reviewed against the elevation, floodproofing and floodway standards of chapter 30.65 SCC and FEMA's June 2020 Flood Insurance Study.
Flood Hazard Permit Required in Flood Zones
Significant RestrictionsSCC 30.43C.020; SCC 30.65.010
30.65.010 Purpose and applicability. The purpose of this chapter is to protect the public health, safety and welfare in those areas subject to periodic inundation due to flooding, and to minimize losses due to flood conditions in the specific areas subject to this chapter by utilizing the methods and provisions set forth herein. The regulations set forth herein shall apply to all development in...
Boat Dock Permits
Snohomish County's Shoreline Management Program caps private dock length, width and boathouse size within shoreline jurisdiction. Single-family docks on marine shorelines top out at 90 feet from the ordinary high water mark, six feet wide, and boathouses are capped at 500 square feet and 12 feet tall.
Boat Dock Rules in Unincorporated Snohomish County
Some RestrictionsSCC 30.67.517(1)(h)(ix)(E)
(E) Pier and dock requirements for marine shorelines. (I) Piers and docks located on marine shorelines shall be the minimum size required to provide for moorage. (II) Single-family piers or docks shall not exceed 90 feet in length measured perpendicularly from the OHWM. Shared moorage may extend up to 110 feet in length if demonstrated to be necessary to provide adequate moorage. (III) The maxi...
Vehicle Idling Restrictions
In unincorporated Snohomish County, running or idling a stationary truck over 10,000 pounds GVWR for more than ten minutes at a stretch at night is classified as a public disturbance noise. The rule applies only in rural and residential districts and is enforced by the Sheriff's Office under SCC 10.01.040(2)(d), with fines starting at $50.
Snohomish County Bars Truck Idling at Night
Some RestrictionsSCC 10.01.040(2)(d)
(2) Public Disturbance Noises, at Night in Rural or Residential Districts. Sounds resulting from the following activities are determined to be public disturbance noises when they occur at night and noise is received on property in a rural or residential district. ... (d) The operation or idling, for more than ten minutes at a time, of stationary trucks weighing in excess of 10,000 pounds GVWR, ...
Flood Elevation Requirements
Unincorporated Snohomish County requires new and substantially improved buildings in mapped special flood hazard areas to sit at least one foot above the base flood elevation. Critical facilities like fire stations and shelters must clear it by three feet, and mechanical equipment needs the same one-foot buffer.
Base Flood Elevation & Freeboard in Snohomish County
Some RestrictionsSCC 30.65.120(2)(a), (5)
In AE and A1-30 zones or other A zoned areas, where the base flood elevation has been determined, new construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated a minimum of one foot above the base flood elevation. Mechanical equipment and utilities shall be waterproof or elevated at least one foot above base flood elevation. ...
Environmental Rules by City in Snohomish County
4 cities in Snohomish County have their own environmental rules rules. Each link goes to that city's dedicated page with code citations.
5 verified rules • Boat Dock Permits, Erosion Control
5 verified rules • Boat Dock Permits, Erosion Control
5 verified rules • Boat Dock Permits, Erosion Control
4 verified rules • Erosion Control, Flood Elevation Requirements
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