The river is not named after a tribe. The tribe is named after where it lived. Duwamish is an anglicisation of dxʷdəwʔabš — rendered in plainer type as Dkhw'Duw'Absh — meaning "People of the Inside": inside the bay, up the sheltered water, away from the open Sound.

The Tribe's own account distinguishes the dxʷdəwʔabš, around Elliott Bay and the river, from the xacuabš, "People of the Large Lake," around Lake Washington. Before 1916 those waters belonged to one drainage joined by the Black River—a hydrology the twentieth century dismantled.

Lushootseed spellings vary between sources. We retain the form used by each cited source rather than making the words look more certain than our research allows.

At the mouth of the river the Port of Seattle now runs two small parks on old village ground. One is named həʔapus — a name spoken for the Port by Warren King George, historian of the Muckleshoot Indian Tribe — for a small stream draining across a flat on the river's west side. It sits on the site of a village called yile'qwud, named for a Yakama-style basket hat, where families lived communally in cedar plank longhouses.

National Register documentation dates Coast Salish settlement here as early as 1999 BC—an occupation record measured in millennia rather than the 175 years of Seattle's customary founding story.

t̓uʔəlaltxʷ — "Herring's House," the place where herring spawn — stood near the mouth of the river. In March 1893 eight dwellings were burned and their residents displaced. The Port of Seattle, which now maintains a park on the site, states it plainly: the village "was burnt down in 1893 by settlers looking to advance their land holdings during expansion into West Seattle."

The burning entered the newspaper record when displaced residents arrived at Ballast Island, one of the few places Native people were permitted to camp in the city. A man the paper called West Seattle Charlie identified James Watson of the West Seattle Land and Improvement Company as the arsonist; the original paper has not yet been checked.

Five years later, dock and warehouse expansion ended Native residence on Ballast Island too. The formal exclusion imposed by Seattle's 1865 ordinance continued through fire, land acquisition, and industrial expansion.

The lower Duwamish met Elliott Bay in meanders, and at high water much of the surrounding land was under it. Steamboats could get as far as Kent; ocean-going ships could not get in at all. That was the problem the twentieth century set out to solve.

Eugene Semple proposed the scheme in 1895: a canal to Lake Washington, filled tideflats, and a straightened river. In 1909 Seattle formed the Duwamish Waterway Commission, sold bonds, and began dredging in Georgetown.

Twenty million cubic yards of mud and sand were moved. The bends were filled and the channel deepened; by 1920 the waterway ran fifty feet deep for four and a half miles. Land appeared where water had been, and industry moved south onto it.

City Engineer R. H. Thomson urged the project. His work here and on Seattle's regrades made him one of the people most responsible for the city's physical shape.

Lake Washington's outlet was the Black River, which ran south from Renton, met the Cedar half a mile down, joined the Green at what is now Tukwila, and became the Duwamish. The Duwamish had a village on it for at least fourteen hundred years.

Building the Lake Washington Ship Canal meant dropping the lake to the level of Lake Union. On 25 August 1916 the cofferdam holding Lake Union out of the Montlake Cut was opened; three days later the gates at the Lake Washington end were opened too. Over three months the lake fell nine feet — below the mouth of its own outlet. The Black River stopped.

Renton had already diverted the Cedar River into the lake in 1912. When the lake fell, the Black-Cedar salmon run arrived to find receding water. Treaty fishing rights remained on paper while the project removed fish, river, and landing from this place.

Straightening the river did not delete the old channel. It left it in the plats.

In Georgetown, S Front Street, S Fidalgo Street and S River Street still curve. They are not curved for a view or a hill. They follow a bend of the Duwamish that has not held water for a century, because the lots were laid out along the riverbank and the lot lines outlived the river.

Open the parcel map over Georgetown and the parcels themselves trace the meander. A buildable-envelope calculation on those lots is taking place inside the footprint of a river dredged away in 1913.

The Environmental Protection Agency added the Lower Duwamish Waterway to the National Priorities List in 2001 — the five northern miles of the river, up to the southern tip of Harbor Island, plus the upland sources feeding it.

The contaminants of concern are PCBs, arsenic, carcinogenic PAHs, dioxins and furans. In 2014 the EPA issued its Record of Decision: active cleanup of roughly 177 acres by dredging, capping and enhanced natural recovery, at an estimated $342 million.

The waterway was completed in 1920 and listed as a national priority for contamination in 2001. Cleanup was still under way when this panel was last checked.

The Washington Department of Health advises against eating resident crab, shellfish and non-salmon fish from the waterway. Salmon are the exception, and only because they pass through quickly.

People fish it anyway, and the EPA knows precisely who: a 2016 study of fishers on the Duwamish found more than twenty ethnic and language groups, many of whom eat and share what they catch. The agency's consumption-advice materials are produced in Khmer, Spanish and Vietnamese among others.

A consumption advisory asks the person reading it to avoid a risk created elsewhere. That choice is hardest for people who rely on the river for affordable food, cultural practice, or both.

It also runs directly into the treaty. Point Elliott reserved the right of taking fish at usual and accustomed grounds. It did not reserve the right to eat them.

In 2013 Just Health Action and the Duwamish River Cleanup Coalition published a Cumulative Health Impacts Analysis of the valley: fifteen indicators across ten Seattle zip codes, scored together rather than one pollutant at a time.

The analysis estimated life expectancy in South Park and Georgetown at 73.3 years—eight years below the Seattle and King County average at the time, and thirteen years below Laurelhurst.

The figures date to 2013. They describe how far apart health outcomes could be within one city after a century of decisions about the valley.

Seattle's tree canopy covered 28.1 percent of the city in 2021, down from 28.6 percent in 2016—a loss of 255 acres in five years.

The citywide average conceals a widening divide. The City's assessment found 31 percent less canopy in neighborhoods shaped by racial and economic injustice in 2021, compared with 27 percent less in 2016. The Duwamish Valley is among those places.

The tree-canopy layer is therefore more than a map of where trees grow. It also records where shade, maintenance, and long-term investment accumulated.

From 1937 to 1993 the site at the end of Dallas Avenue South held the Duwamish Manufacturing Company and then Malarkey Asphalt. It became Terminal 117, and then it became one of the most PCB-contaminated pieces of ground on the river.

Beginning in 2007, South Park residents and the Duwamish River Cleanup Coalition argued that the site should return to the neighborhood. After shoreline and neighborhood cleanup, the park opened in 2022 with fourteen acres of habitat and roughly 2,500 feet of public shoreline, including refuge for juvenile Chinook.

Fourteen acres cannot balance five miles of Superfund waterway or twenty million cubic yards of moved ground. It is nevertheless a material return of shoreline and habitat—and something South Park residents asked for and helped shape.