The Stillaguamish River is a river in the northwestern region of the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sove ...

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

. It is mainly composed of two forks, the longer North Fork Stillaguamish () and the South Fork Stillaguamish. The two forks join near Arlington. From there the Stillaguamish River proper flows for to

Puget Sound Puget Sound ( ) is a sound of the Pacific Northwest, an inlet of the Pacific Ocean, and part of the Salish Sea. It is located along the northwestern coast of the U.S. state of Washington. It is a complex estuarine system of interconnected ma ...

. The river's watershed drains part of the

Cascade Range The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, ...

north of

Seattle Seattle ( ) is a seaport city on the West Coast of the United States. It is the seat of King County, Washington. With a 2020 population of 737,015, it is the largest city in both the state of Washington and the Pacific Northwest regio ...

Course

The Stillaguamish River is formed from the confluence of the North and South Forks, both of which rise in the Cascades. Between the North and South forks there is a portion of the

Mount Baker-Snoqualmie National Forest Mount is often used as part of the name of specific mountains, e.g. Mount Everest. Mount or Mounts may also refer to: Places * Mount, Cornwall, a village in Warleggan parish, England * Mount, Perranzabuloe, a hamlet in Perranzabuloe parish, C ...

called the

Boulder River Wilderness Boulder River Wilderness is a wilderness area within the Mount Baker-Snoqualmie National Forest in the western Cascade Range of Washington state. Topography Boulder River Wilderness is made up of dense forests and steep ridges that rise to ...

. The North Fork rises as several branches in a remote area of

Skagit County Skagit County is a county in the U.S. state of Washington. As of the 2020 census, the population was 129,523. The county seat and largest city is Mount Vernon. The county was formed in 1883 from Whatcom County and is named for the Skagit Ind ...

near Finney Peak, approximately north of Darrington. Collecting many tributary creeks, the river flows south, then west through the foothills along the Skagit- Snohomish county line. Tributaries of the North Fork Stillaguamish River include Boulder River and Deer Creek. The South Fork () originates from the northern slopes of Del Campo Peak and Morning Star Peak in central Snohomish County, south of Darrington, and flows west and northwest by Silverton,

Verlot Verlot is a census-designated place (CDP) in Snohomish County, Washington, United States. The population was 285 at the 2010 census. Geography Verlot is located at (48.085938, -121.762863). According to the United States Census Bureau, the CDP ...

, and Granite Falls. The two forks unite at Arlington in northwestern Snohomish County. The combined stream flows west before it briefly splits again to encircle the town of Silvana. The Stillaguamish bifurcates at its

delta Delta commonly refers to: * Delta (letter) (Δ or δ), a letter of the Greek alphabet * River delta, at a river mouth * D ( NATO phonetic alphabet: "Delta") * Delta Air Lines, US * Delta variant of SARS-CoV-2 that causes COVID-19 Delta may also ...

to form Florence Island before entering

. Hatt Slough flows southwest and is now the primary distributary of the Stillaguamish waters into

Port Susan Port Susan is a bay and strait located in the U.S. state of Washington. Part of the Whidbey Island Basin of Puget Sound, Port Susan is bounded by Camano Island to the west and the mainland to the east. The Stillaguamish River empties into the nort ...

, having been diverted in the early twentieth century. The Old Stillaguamish River Channel flows northwest towards

Florence Florence ( ; it, Firenze ) is a city in Central Italy and the capital city of the Tuscany region. It is the most populated city in Tuscany, with 383,083 inhabitants in 2016, and over 1,520,000 in its metropolitan area.Bilancio demografico an ...

and then Stanwood on an 8 mile meandering course. Near the

Camano Island Camano Island is a large island in Possession Sound, a section of Puget Sound. It is part of Island County, Washington, and is located between Whidbey Island and the mainland (Snohomish County) by the Saratoga Passage to the west and Port Susa ...

bridge this channel again splits, forming

Leque Island Leque Island is a small island located in Snohomish County, in Washington, United States. It can be found just beneath the bridge between Camano Island and Stanwood, at the mouth of the Stillaguamish River, in Puget Sound. Like the larger Flor ...

, with the South Pass flowing into Port Susan and the West Pass emptying into the southern end of

Skagit Bay Skagit Bay is a bay and strait located in the U.S. state of Washington. It is part of the Whidbey Island Basin of Puget Sound. The Skagit River empties into Skagit Bay. To the south, Skagit Bay connects with the rest of Puget Sound via Saratoga ...

Natural history

The Stillaguamish River and its tributaries are known for their

salmon Salmon () is the common name for several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the family (biology), family Salmonidae, which are native to tributary, tributaries of the ...

runs. Eight salmonid species use the streams for

spawning Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquat ...

, including Chinook, coho, chum, pink, and sockeye salmon, steelhead trout, sea-run cutthroat, and bull trout.

Hydrology

The north fork of the Stillaguamish river level is monitored by gauges operated by the

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

(USGS), and river levels can vary by as much as . The river level rises and falls very quickly, with the average north fork flood duration of eight hours. Of the five highest north fork flood levels on record, three have occurred since 2009.

History

Variant names for the Stillaguamish River, according to the USGS, include Tuxpam River, Stoh-luk-whahmpsh River, Stillaquamish River, Steilaguamish River, Stalukahamish River, and other similar spellings. The 2014 Oso landslide occurred on the North Fork of the Stillaguamish.

References

External links