Overview

Located in South Seattle the lower 5 miles of the Duwamish River is one of the most industrialized and polluted bodies of water in Washington State.  Contributors of this pollution include urban sewage discharge from Seattle and King county as well as industrial waste from manufacturing and port facilities.  In 2001 the Environmental Protection Agency (EPA) listed the Duwamish River in South Seattle as a Superfund cleanup site.  Since then they have taken steps to create a proposed cleanup plan that is currently in the public review phase. 

History

The effects of urbanization on the Duwamish River has caused many changes in the biota as well as the physical structure of the river. 


Images of the Duwamish River in 1906 and how it looks today.  Photo from www.duwamishalive.org (Blomberg, 2012)

Before the area around it was industrialized, the Duwamish River consisted of 14 miles of meandering waterways and an interlinked system of wetlands and marshes.  The Black, Green, Cedar and White Rivers all flowed into the Duwamish, which then emptied into the Puget Sound at Elliot Bay.  The White River was diverted into the Puyallup River in 1906 in order to control flooding, and in 1916 the Cedar River was diverted into Lake Washington.  This has resulted in a flow reduction of about 70%, affecting the transport of sediment within the Duwamish River (4).  The effects of dredging, straightening and adding permanent concrete barriers has further transformed this river into a deep, 5 mile long channel.  By 1986 only about 2% of the historic wetlands remained (14). 

After 100 years of urban use the Duwamish is contaminated with many chemicals including polychlorinated biphenyls (PCBs), dioxins/furans, carcinogenic polycyclic aromatic hydrocarbons (cPAHs), and arsenic (9).  These chemicals are deposited in the river's sediment and have built up to unsafe levels in resident fish and shellfish populations, making them unsafe for consumption. 


Historic path of the Duwamish River (1906), image from http://www.duwamishalive.org/


Current path of the Duwamish River, image from http://www.kingcounty.gov/environment/wtd/Programs/GreenGrants/GrantArea.aspx

This project contains a broad overview of the EPA's currently proposed clean-up plan as well as a discussion of what other information could be helpful and some possible research proposals to that end. It discusses the impact of current pollution and the possible effects of the clean-up on the local animal populations, focusing on native fish and birds.  I also briefly include the effects of this pollution on the health of the local community.