At the southern portion of Elliot Bay, beyond the man-made Harbor Island, is the mouth of the Duwamish River is the name of the lower 12 miles of the Green River.
The river has had a history of man-made upheaval and…well…Industrial contamination/poisoning. Until 1906, the White and Green Rivers joined around present-day Auburn, about twenty-eight miles to the south of Seattle, and then joined the Black River near Tukwila to form the Duwamish River. In 1906, after a massive flood, the White River changed course with the result being it emptying into the Puyallup River as it does today. With the confluence now gone, the lower portion of the White River is now simply considered part of the Green River.
In 1911 the Cedar River was diverted to empty into Lake Washington instead of into the Black River, the result of which included less water flowing in to the Duwamish. Finally, in 1916, with the opening of the Lake Washington Ship Canal, the lake's level dropped nearly nine feet and the Black River dried up. From that time forward, the point of the name change from Green to Duwamish is no longer the confluence of the Green and Black Rivers, though it has not changed location.
In other words, today the Duwamish River is part of Green River, but it used to be the result of the confluence of several other rivers that have since dried up, or have been diverted elsewhere.
Seattle’s economy used to be primarily driven by manufacturing, and all of the industrial aspects of that in which it entails. While the Seattle of today has a more diversified economy, what with the technology, financial, and bio-genetic companies in the area, manufacturing still exists. This can be seen in the area of south Seattle, including the region bordering the Duwamish River.
The result of over one hundred years of industry in this region has resulted in a heavily polluted river. So much so that the Environmental Protection Agency has labeled the river a Superfund site, the environmental program established to address hazardous waste sites.
These pollutants have affected the local wildlife, including the chinook, coho, chum and steelhead, salmon that inhabit the waterways. Many of the animal species found in or around the river contain an unhealthy amount of contaminants. In a memo from the EPA in 2008, they stated, “any type of fish or shellfish found in the river is unfit for human consumption. It was found that PCB levels in fish and crab that live in the waterway most of their lives are 35 to 110 times higher than in Puget Sound salmon.” Their Ecological Risk Assessment also found that river otters from the Lower Duwamish River might be exposed to such high levels of PCBs that the growth or survival of their offspring may be reduced.
Efforts are underway to clean up the area, with current estimates on completing the project pointing to sometime between 2016 -2020.