Stillaguamish Watershed

Location of the Stillaguamish Watershed in Washington State.  Map courtesy of the EPA.The fifth largest tributary draining into Puget Sound, the Stillaguamish River is part of a watershed that covers 700 square miles from sea level to an elevation of 6,854 feet. The North Fork and South Fork of the river join in Arlington, where they form the Lower Mainstem that travels 18 miles to Stanwood, where it meets Puget Sound. Forestry is the dominant land use, followed by rural residential development.

The climate tends toward cool winters with high rainfall, which varies from 30 inches annually in the lowlands to 150 inches at the high peaks. Low flows occur during the summer, between July and October.

EPA watershed profile:

  • Counties: Skagit, Snohomish
  • National Estuary Programs: Puget Sound
  • Other Watersheds Upstream: None
  • Other Watersheds Downstream: Puget Sound

Related WRIA: 05

All Puget Sound WRIAs


Stillaguamish Watershed Chinook Salmon Recovery Plan

Department of Ecology



Report cover photo by Victor Mesny.

Climate change vulnerability and adaptation in the North Cascades Region, Washington

A 2014 report by the North Cascadia Adaptation Partnership identifies climate change issues relevant to resource management in the North Cascades, and recommends solutions that will facilitate the transition of the diverse ecosystems of this region into a warmer climate.

Stillaguamish River (North Fork) valley

Influence of climate and land cover on river discharge in the North Fork Stillaguamish River

A 2014 report prepared by the Stillaguamish Tribe analyzes potential causes of changes in peak and low flows in the Stillaguamish River basin. 


Stillaguamish Tribe

The Stillaguamish Tribe is descended from the Stoluck-wa-mish River Tribe, who signed the treaty of Point Elliott in January 1855. Some tribal members moved to the Tulalip reservation, while others remained along the Stillaguamish River. The headquarters for the tribe are in Arlington, Washington.

Stillaguamish Area of Concern: