The Swinomish Channel is an long salt-water channel in

Washington state Washington, officially the State of Washington, is a state in the Pacific Northwest region of the United States. It is often referred to as Washington State to distinguish it from the national capital, both named after George Washington ...

, United States, which connects Skagit Bay to the south and

Padilla Bay Padilla Bay is a bay located in the U.S. state of Washington (state), Washington, between the San Juan Islands and the mainland. Fidalgo Island and Guemes Island lie to the west of Padilla Bay. Guemes Channel, between the islands, connects Padil ...

to the north, separating Fidalgo Island from mainland

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 Upper and ...

. The Swinomish Channel is the smallest of the three entrances to

Puget Sound Puget Sound ( ; ) is a complex estuary, estuarine system of interconnected Marine habitat, marine waterways and basins located on the northwest coast of the U.S. state of Washington (state), Washington. As a part of the Salish Sea, the sound ...

—the other two being

Deception Pass Deception Pass (; ) is a strait separating Whidbey Island from Fidalgo Island, in the northwest part of the U.S. state of Washington (state), Washington. It connects Skagit Bay, part of Puget Sound, with the Strait of Juan de Fuca. A pair of bri ...

and Admiralty Inlet. The Swinomish Channel is partly natural and partly dredged. Before being dredged, it was a collection of shallow tidal

sloughs A slough ( or ) is a wetland, usually a swamp or shallow lake, often a Backwater (river), backwater to a larger body of water. Water tends to be Water stagnation, stagnant or may flow slowly on a seasonal basis. In North America, "slough" may re ...

salt marsh A salt marsh, saltmarsh or salting, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. I ...

es, and

mudflat Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal ...

s known as Swinomish Slough. The

United States Army Corps of Engineers The United States Army Corps of Engineers (USACE) is the military engineering branch of the United States Army. A direct reporting unit (DRU), it has three primary mission areas: Engineer Regiment, military construction, and civil wo ...

used dredging and diking to create a navigable channel, completed in 1937 during the

Great Depression The Great Depression was a severe global economic downturn from 1929 to 1939. The period was characterized by high rates of unemployment and poverty, drastic reductions in industrial production and international trade, and widespread bank and ...

. The channel is heavily used by fishing boats, tugs, recreational craft, and shallow-draft freight vessels. To maintain navigable depths, the Swinomish Channel must be dredged at least every three years. Dedicated federal funding for continued dredging was eliminated in the 1990s. A study in 2004–2008 determined that sedimentation would render the channel's north end impassable for virtually all vessels by 2015, and its south end by 2019. The channel was dredged again in 2008. In 2012 the Army Corps of Engineers received funding from Congress for another dredging project, which was finished in January 2013. The channel was most recently dredged in 2024.

References

Channels of the United States Bodies of water of Skagit County, Washington Bodies of water of Washington (state) Washington (state) placenames of Native American origin {{SkagitCountyWA-geo-stub