The state Shoreline Management Act (SMA) defines a special category of shorelines where statewide interests take priority and specific uses are preferred. These "shorelines of statewide significance" include certain marine areas and larger streams, rivers, and lakes in Washington.
There are three different types of marine areas considered to be shorelines of statewide significance:
- Pacific Ocean coastline, from Cape Disappointment to Cape Flattery — including all the harbors, bays, estuaries, and inlets seaward from the ordinary high water mark and all associated shorelands.
- Specific estuarine areas, including Birch Bay, Hood Canal, Nisqually River delta, Padilla Bay and Skagit Bay situated between the ordinary high water mark and the extreme low tide line and associated shorelands.
- All other areas of Puget Sound, Strait of Juan de Fuca, and adjacent saltwater areas lying waterward of the extreme low tide, excluding adjacent tidelands and shorelands.
Streams and rivers
Streams and rivers, along with associated segments and uplands meeting one of the following criteria, are considered shorelines of statewide significance:
- West of the Cascade Mountains — Rivers with a mean annual flow of 1,000 cubic feet per second or more.
- East of the Cascade Mountains — Rivers that have a mean annual flow of 200 cubic feet per second or more and river segments located downstream from the first 300 square miles of the drainage area.
Specific river segments meeting the criteria are indicated with an asterisk in the county list under Chapter 173-18 WAC.
Lakes that are 1,000 acres in size or more and all associated shorelands are considered shorelines of statewide significance. They are listed by county under Chapter 173-20 WAC.