What is the Seattle Shoreline Management Act?

Washington's Shoreline Management Act of 1971 regulates development near the state's shorelines to protect public access, ecological function, and water quality. Seattle has one of the most active shoreline permitting regimes in the state because of Lake Washington, Lake Union, Puget Sound, and the Ship Canal.

What triggers SMA review in Seattle:

Development within 200 feet of the ordinary high water mark of:

• Puget Sound.
• Lake Washington.
• Lake Union.
• Lake Sammamish (small portion).
• Ship Canal.
• Portage Bay.
• Green Lake.
• Longfellow Creek (sections).
• Duwamish River.

Types of shoreline approvals:

1. Shoreline Substantial Development Permit (SSDP) — for most development exceeding exempt thresholds. Reviewed by Seattle Department of Construction and Inspections (SDCI), appealable to the Shorelines Hearings Board.

1. Shoreline Conditional Use Permit (SCUP) — for uses not allowed by right in the shoreline zone.

1. Shoreline Variance — for dimensional deviations (setbacks, height).

1. Exemption Letter — for work below thresholds (small repair work, single-family residences meeting specific criteria).

Thresholds for exemption:

• Single-family residence of normal size and configuration meeting all setback and height rules.
• Repair and maintenance of existing legal structures.
• Normal agricultural practices.
• Development under $22,500 (2026 dollar threshold).

What typically requires a permit (not just exemption):

• New bulkhead or bulkhead replacement.
• Dock additions or replacements.
• Additions to existing homes that extend closer to shoreline.
• Accessory structures (boathouses, decks).
• Significant vegetation removal within shoreline jurisdiction.

Typical costs and timeline:

• Exemption letter: $250-$1,000; 2-6 weeks.
• SSDP: $3,000-$10,000 plus consultant soft costs; 4-9 months.
• SCUP: $5,000-$15,000; 6-12 months.

Consultant costs often exceed permit fees:

• Biological evaluation: $3,000-$15,000 (required for many applications).
• Shoreline survey: $2,000-$5,000.
• Habitat assessment: $2,000-$8,000.
• Landscape architect for vegetation plan: $2,000-$6,000.

Salmon-specific concerns:

• Seattle's shorelines are critical Chinook salmon habitat.
• Any work that could affect salmon habitat triggers federal ESA review (separate from SMA) — coordinated through WDFW.
• HPA (Hydraulic Project Approval) from WDFW usually required for in-water work.

Don't confuse with:

• Critical Areas Ordinance — separate Seattle regulation for wetlands, steep slopes, fish/wildlife habitat, and aquifer recharge areas.
• Floodplain regulations — separate FEMA/city regulations for flood-prone areas.

AskBaily's Seattle contractor pool is familiar with SDCI shoreline permits and works with biologists and wetland consultants for coastal projects. See /seattle for deeper local context.