The Duwamish River
is the name of the lower reach of Washington
state's Green River
. Its industrialized estuary is known as the Duwamish Waterway
. At one time, the Green, Black, and White
Rivers joined to form the Duwamish; however, in 1907 the White River was diverted into the Puyallup. A few years later the Cedar River was diverted to empty into Lake Washington
instead of the Black River, though the lake itself still emptied into the Black. Then, with the opening of the Lake Washington Ship Canal
in 1916, the lake's level dropped nearly nine feet and the Black River dried up. Hence the point of the name change is no longer the confluence of three rivers, though it has not changed location.
The Duwamish Waterway empties into Elliott Bay in Seattle, divided by the man-made Harbor Island into two channels, the East and West Waterways.