Environmental Rules in Seattle, WA (2026)
6 verified environmental rules for Seattle, Washington, sourced directly from the municipal code and official government pages.
Verified from official government sources
Stormwater Management
Seattle's Stormwater Code requires every development project to maintain natural drainage patterns and prevent adverse impacts to receiving waters, under SMC 22.805.020. Discharge points must preserve natural pathways and match downstream drainage capacity. Seattle Public Utilities and the Department of Construction and Inspections jointly enforce the code, and violations draw civil penalties up to $5,000 per day under SMC 22.808.050.
Seattle Stormwater Code Governs Site Drainage
Some RestrictionsSeattle Municipal Code § 22.805.020
22.805.020 - Minimum requirements for all projects A.Minimum requirements for maintaining natural drainage patterns. For all projects, natural drainage patterns shall be maintained and discharges shall occur at the natural location to the maximum extent feasible and consistent with subsection 22.805.020.B. Drainage water discharged from the site shall not cause a significant adverse impact to r...
Erosion Control
Seattle grading permits require erosion control from cut and fill slopes and cleared areas, per SMC 22.170.070. SDCI can demand a written plan for minimizing sediment, requires inspection of erosion and drainage control measures during work under 22.170.130, and won't sign off final approval under 22.170.140 until all erosion control measures are complete.
Seattle Construction Erosion Control Rules
Some RestrictionsSeattle Municipal Code § 22.170.070(C)(2)(a); § 22.170.140(A)
2. Required after initial screening. The Director may require the following information after the initial screening of a grading permit application: a. Sediment and pollution. A description of methods to be used to minimize sediment or other pollution from leaving the site during and after construction and to protect cleared areas and cut and fill slopes from erosion. ... [22.170.140.A] Final I...
Flood Zones
Seattle requires a floodplain development permit before any construction, fill, or substantial improvement in FEMA-mapped special flood hazard areas, per Seattle Municipal Code Chapter 25.06. SDCI administers approvals citywide; SDOT handles work in the public right-of-way. Violators face a cumulative civil penalty of $500 per day until compliance is achieved.
Seattle Floodplain Development Approval Required
Some RestrictionsSeattle Municipal Code § 25.06.060
Construction or development including the placement of or substantial improvement to manufactured homes and recreational vehicles not ready for highway use, shall not be undertaken within any special flood hazard area and flood-prone areas as defined in subsection 25.09.012.B as established in Section 25.06.050 without approval under this Chapter 25.06. For development where no other permit or ...
Sea Wall & Bulkhead
Seawall and bulkhead maintenance in Seattle is regulated under the Shoreline Master Program (SMC 23.60A) and the Washington Shoreline Management Act. Work on seawalls within the shoreline district requires a Shoreline Substantial Development Permit or exemption from SDCI. Environmental review under SEPA may be required for significant projects.
Seattle Seawall and Bulkhead Maintenance Regulations
Heavy RestrictionsSeattle Municipal Code 23.60A — Shoreline Master Program (SDCI)
Shoreline Master Program — The Shoreline Master Program (23.60A) regulates development in the city's shoreline environments to: Protect shoreline ecosystems; Encourage water-dependent uses; Provide for public access and enjoyment of the shorelines. Our ordinance requires that you: Obtain a shoreline substantial development permit, or a shoreline exemption, for any development in the Shoreline D...
Boat Dock Permits
Installing or modifying boat docks in Seattle requires permits under the Shoreline Master Program (SMC 23.60A), federal Army Corps Section 10 permits, and potentially Washington Department of Ecology approvals. Docks must comply with environmental standards protecting salmon habitat and water quality. SDCI reviews all dock proposals within the shoreline district.
Seattle Boat Dock and Moorage Permits
Heavy RestrictionsSDCI Shoreline Permits (Land Use / Master Use Permit - Shoreline, SMC 23.60A)
Land Use / Master Use Permit - Shoreline — Properties within the shoreline district (overwater and on land within 200 feet of the shoreline significant water bodies) are regulated by the Seattle Shoreline Master Program (SMP) in addition to other applicable requirements. Therefore, you may need to apply for a land use permit for any project in the shoreline. The Shoreline District within the Ci...
Flood Elevation Requirements
Seattle requires new construction in A-zone flood hazard areas to sit at least three feet above the base flood elevation, per SMC 25.06.030's definition of 'flood protection elevation.' SMC 25.06.110 applies the standard to residential and nonresidential buildings citywide, enforced by the Seattle Department of Construction and Inspections.
Seattle Flood Protection Elevation Freeboard Rule
Some RestrictionsSeattle Municipal Code § 25.06.030
"Base flood elevation (BFE)" or "base flood level" means the level or elevation above mean sea level, as calculated by reference to the vertical datum of NAVD 88, to which floodwater is anticipated to rise during the base flood. ... "Flood protection elevation" means the following unless otherwise permitted by code:1.Base flood elevation in the VE zone; and2.For A zones:a.Three feet above the b...
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County ordinances apply to unincorporated areas and may supplement Seattle city rules.
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