Stream and river shorelines

Note: The Shoreline Management Act (SMA) uses streams and rivers interchangeably.

The current official list of streams that meet the 20 cubic feet per second (cfs) mean annual flow criteria is found in state rule at WAC 173-18. The WAC 173-18 list WILL BE SUPERSEDED by lists contained in Ecology-approved shoreline master programs. WAC 173-18-044, adopted February 2, 2007 states:

Each local government master program shall include a list of streams constituting shorelines of the state within the jurisdiction of the master program that complies with the requirements of RCW 90.58.030 (2)(d). When such master program is approved by the department, subsequent to the effective date of this provision, the list within the master program shall be the official list for that jurisdiction and shall supersede the list contained herein.

Streams and rivers west of the Cascades crest with a mean annual flow of 1,000 cfs or greater, and east of the Cascades crest with either a mean annual flow or 200 cfs or more or the portion downstream from the first 300 square miles of drainage areas are classified as shorelines of statewide significance.

Shoreline data

Visit Ecology's Coastal Atlas and click on SMA jurisdiction under the "Regulated Features" layer for a graphic display of streams meeting this criteria.

Download the current WAC 173-18 streams list AND the proposed list from Ecology's GIS Data. Look for "shoreline management act" in the alphabetized subject list.

Spreadsheet of list of streams

Ecology's list of streams is based on the results of three USGS regional stream flow studies with corrections based on locally supplied flow data. The spreadsheet lists the specific point at which every stream or river in the state flows at 20 cubic feet per second mean annual flow, as predicted by the USGS studies, as corrected. The spreadsheet also lists the points at which streams and rivers are determined to be shorelines of statewide significance according to the criteria provided by RCW 90.58.030(c), (d), and (e). Local governments should use the spreadsheet list as a starting point for establishing the preliminary boundaries of shoreline jurisdiction.

For more information

Rule: WAC 173-18 - list of streams that meet the 20 cfs mean annual flow criteria