Environmentally Critical Areas (ECA) Code

See also: Land Use / Master Use Permit - Environmentally Critical Areas (ECA), Tree Protection Code, Shoreline Master Program Code

What Is It?

Our Environmentally Critical Areas (ECA) Code governs areas of Seattle that provide critical environmental functions. For example, wetlands protect water quality and provide fish and wildlife habitat. Our ECA code also addresses areas that represent particular challenges for development due to geologic or other natural conditions. The goal of our ECA regulations, (Seattle Municipal Code (SMC) chapter 25.09) is to effectively protect these areas and to protect public safety, while allowing reasonable development in our growing city.

Designated environmentally critical areas are defined in SMC 25.09.012 and are generally described as:

• Geologic hazard areas including:
  • Landslide-prone areas (including potential landslide areas and  known landslide areas)
  • Liquefaction-prone areas (sites with loose, saturated soil  that lose the strength needed to support a building during earthquakes)
  • Peat-settlement-prone areas (sites containing peat and organic soils that may settle when the area is developed or the water table is lowered)
  • Seismic hazard areas
  • Steep slope erosion hazard areas
  • Volcanic hazard areas
• Flood-prone areas
• Wetlands
• Fish and Wildlife Habitat Conservation Areas including:
  • Riparian watercourses (all streams and Haller and Bitter Lakes)
  • Riparian Management Areas (the land within 100 feet of riparian watercourse)
  • Areas designated by Washington State Department of Fish and Wildlife as priority habitats and species areas
  • Areas designated by our Director as habitat for species of local importance
  • Corridors connecting priority habitats and species areas or habitat areas for species of local importance, when certain criteria are met
• Abandoned landfills

You can use our online map tool to see if your property has any mapped ECAs. Turn on the ECA layer under the "Layer List" on the right-hand side of the map. Most of these maps are advisory; they help identify potential ECAs on your property. We will use detailed property information, such as a topographic survey or wetland report, to confirm if an ECA is present. There are some types of ECAs that we are required to identify based on the maps; for example, priority habitat areas identified by the Washington Department of Fish and Wildlife and peat-settlement prone areas. Your property may also have ECAs that are not shown on our maps.

Environmentally Critical Areas within the Shoreline District

The ECA regulations prior to the 2017 update apply if your project is within the Shoreline District, which includes all land within 200 feet of the shoreline, hydrologically connected wetlands, and all submerged land. Use our online map tool to see if your project is within the Shoreline District. Turn on the Shoreline Environments layer under the "Layer List" on the right-hand side of the map.

Read the Code

If you have an ECA on your property, you will need to comply with the rules that apply to that ECA. You can find detailed definitions of each ECA in Regulations for Environmentally Critical Areas (SMC 25.09). However, the Tips listed below and Director's Rule 13-2018 do not apply to ECA's within the Shoreline District. You need to look at the ECA regulations prior to the 2017 update. 

• Director's Rule 19-2006, Requirements for Wetland Professionals and Wetland Delineation Reports
• Director's Rule 30-2006, Update of Wetland Environmentally Critical Areas Mapping
• Director's Rule 3-2007, Application Submittal Requirements in Environmentally Critical Areas
• Director's Rule 4-2007, Permanent Markers Delineating ECAs and Associated Buffer Areas
• Director's Rule 14-2008, Infiltration Facilities in Peat Settlement-Prone Areas
• Director's Rule 13-2018, Great Blue Heron Management
• Tip 103B, Environmentally Critical Area Site Plan Requirements
• Tip 325, Environmentally Critical Areas: Peat Deposits
• Tip 327A, Environmentally Critical Areas Exemptions, Relief from Prohibition on Steep Slope Development, and Modifications to Submittal Requirements — Application Instructions and Submittal Requirements
• Tip 327B, Environmentally Critical Areas — Small Project Waivers Application Instructions and Submittal Requirements
• Tip 328, ECA Exceptions
• Tip 329, ECA Administrative Conditional Use Permit—Application Instructions and Submittal Requirements
• Tip 330, ECA — Yard & Setback, Steep Slope and Wetland Buffer Variances
• Tip, 331, Environmentally Critical Areas: Trees and Vegetation
• Tip 331A, Environmentally Critical Areas: Vegetation Restoration
• Tip 331B, Hazard Trees