The Lower Duwamish: History and Promise
The Duwamish River begins as the Green River in the Cascade Mountains of southeast King County. The Green becomes the Duwamish 12 miles from its mouth at Harbor Island in Seattle’s Elliott Bay. The river originally followed a winding course in the Duwamish Valley through south Seattle. Beginning in 1913, the Duwamish River was straightened into the Duwamish Waterway to facilitate navigation and industrial development.
Over the years chemical contamination, mostly from industry, accumulated in the waterway’s sediments — the mud and silt that form the banks and bottom. Below are steps taken by the U.S. Environmental Protection Agency (EPA) and the Washington Department of Ecology to cleanup the Waterway:
- In 1988 the EPA investigated the sediments in the waterway and found many harmful chemical compounds and toxic metals.
- In 2001 the EPA listed about five-and-a-half miles of the Duwamish — between the southern tip of Harbor Island to the end of the straightened waterway in Tukwila — as a federal Superfund site. The EPA’s Superfund List includes the nation’s most-contaminated sites, targeting them for investigation and clean-up.
- In February 2002 Ecology added the Duwamish to the Washington state’s Hazardous Sites List.
- In April 2002 EPA and Ecology signed an agreement dividing the responsibilities for the site. EPA is the lead agency for the investigation of sediment contamination, while Ecology is the lead agency for controlling sources of pollutants to the sediments.
The status of each source control project changes constantly and Ecology updates
this information on the Toxic Cleanup Program's
Lower Duwamish Waterway site.
Pollution Pathways to the River
Pollution travels to the Duwamish Waterway through three primary channels:
- Stormwater: This is the rainwater runoff from roads, roofs, parking lots and other hard
surfaces. Stormwater picks up much debris and pollution as it flows into urban waters and sediments.
- Combined Sewer Outfalls: Where sanitary and storm sewers are combined, heavy rainfalls can overwhelm the capacity of the system, resulting in raw sewage being discharged into urban waters and sediments.
- Groundwater: When contamination spills or leaks into the ground, groundwater flow can gradually move pollutants toward the river. Identification and cleanup of contaminated soil and groundwater form some of the most significant – and complex – source control work in the area.
Source Control in the Lower Duwamish Waterway
Source control is about finding and then preventing or reducing the release of contaminants that get into the Lower Duwamish sediments. Source control involves an ever-growing and changing list of sites under investigation, along with efforts to prevent contamination of the waterway.
EPA and Ecology
click to enlarge
To focus on source control in the Waterway, Ecology and EPA organized the Source Control Work Group. This group is an interagency body that coordinates the source control work in the Lower Duwamish. Part of the challenge of cleaning and protecting the Lower Duwamish Waterway is the sheer number of pollution sources. Ecology and its partners approach source control in many ways. For example, in 2003, the City of Seattle and King County formed a joint program to conduct business inspections throughout the 20,000-acre Lower Duwamish drainage area. The purpose of this joint program looks for ways to prevent or reduce the flow of pollution that enters the Lower Duwamish through discharges to public storm drains and sanitary/combined sewer systems that discharge to the Lower Duwamish
The Lower Duwamish Urban Waters Initiative:
A Coordinated, Multi-faceted Approach
In 2007 the Lower Duwamish was one of three areas chosen for Washington’s new Urban Waters Initiative. The Legislature approved $775,000 of the program’s $2.5 million 2007-09 budget for the Lower Duwamish Urban Waters Initiative. The initiative provides increased resources to speed up pollution reduction activities, primarily source reduction and source control.
The Urban Waters Initiative supplements and enhances Ecology’s source control efforts for the Lower Duwamish Waterway Superfund Site. It is also part of Washington’s wider Puget Sound Initiative goal of cleaning up and restoring the Sound by 2020. By adding new inspectors from Ecology and local governments, as well as more sampling, the Urban Waters Initiative proposes a comprehensive, multi-program approach meant to:
- Identify potential sources of contamination.
- Ensure that facilities that should have environmental permits do have these permits and are complying with them.
- Perform more inspections of facilities regulated by an environmental permit.
- Assist in developing appropriate source control measures.
- Provide technical assistance on toxics reduction and pollution prevention.
- Build capacity at the local level to safely manage and reduce toxics at small businesses and households.
- Strengthen the partnership between Ecology’s Urban Waters Initiative inspectors and the Seattle/ King County joint inspection program.
More Planning and Coordinating
The task of cleaning up and protecting the Lower Duwamish is complex and requires a coordinated and holistic approach. To avoid duplicating of effort, Ecology is coordinating inspections with the city of Seattle and King County to:
- Create inspection procedures and checklists.
- Identify facilities already inspected.
- Determine the overall strategy for making and coordinating ongoing inspections in the Lower Duwamish basin.
To track inspections and technical assistance visits, Ecology and its local partners have established:
- A common database to create and record inspection reports.
- A single, comprehensive checklist for inspections, to ensure a consistent inspection approach by all agencies.
More Ecology Resources
In the Lower Duwamish, Ecology’s Northwest Regional Office Water Quality and Hazardous Waste Programs will each dedicate one full-time staff member to support this work.
The Water Quality Program will assign a senior inspector to the project to who will:
- Conduct comprehensive inspections of at least 40 facilities per year that have Ecology water-quality permits.
- Inspect facilities without permits to determine if permits are required.
- Join in source tracing efforts with local jurisdictions.
- Conduct joint inspections with local jurisdictions.
The Water Quality Program will also increase the budget for sampling of suspected problem facilities.
The Hazardous Waste Program has already hired a new inspector to:
- Add to the 50-100 field visits currently made by program staff.
- Focus field work on the management of dangerous waste, pollution prevention, complaint response, and stormwater protection.
- Help businesses reduce or eliminate current hazardous waste generation through process improvements, product substitutions and housekeeping changes.
New Local Source Control Specialist
The Legislature also made available additional funds under the Local Source Control Program so that Ecology can contract with a local government within the Lower Duwamish Waterway for a source control specialist. The specialist, in this case from Seattle Public Utilities, will conduct site visits and provide technical assistance. The specialist will seek opportunities to control sources of contaminants that may cause health or environmental problems if they accumulate in waterway sediments.
In the Lower Duwamish, the local source control specialist will:
- Work with smaller businesses to make sure they properly disposal of their waste.
- Respond to issues covered by local laws.
- Refer cases to Ecology if investigation or other action is needed.
The Puget Sound Initiative also provides for up to ten local source control specialists throughout the Puget Sound basin, through contracts with local governments.
These specialists will make site visits directly at industrial, commercial and residential locations. They will:
- Conduct site visits to find pollution sources.
- Advise businesses on pollution control measures.
- Help businesses get the permits they need.
- Make sure that permits are being followed.
Environmental Monitoring: Assessing the Reduction of Toxic Threats
The Lower Duwamish Urban Waters Initiative also supports an existing, ongoing project by Ecology’s Environmental Assessment Program to monitor sediments in the Lower Duwamish River and Elliott Bay. This monitoring will measure the collective effects of all source-control efforts on the reduction of toxic contaminants that are polluting the larger area. It will supplement work managed by Ecology’s Toxics Cleanup Program to monitor and control contaminant sources. These contaminants include the following:
Local governments also collect and analyze environmental samples.
- Heavy metals.
- Toxic organic compounds such as PCBs, solvents and petroleum products.
Ongoing monitoring activities by Ecology and its partners include the following:
- Source identification via sampling, for example, of sewer line and catch basin sediment traps.
- Contaminants entering the Duwamish upstream from the Green River.
- Post-cleanup sediment monitoring by parties determined by Ecology and EPA to be responsible for cleanup actions.
Related Web links
EPA Lower Duwamish Waterway Site
Ecology Lower Duwamish Waterway – Toxic Cleanup Program
Ecology Lower Duwamish Waterway Group
Duwamish River Cleanup Coalition
Also see the most recent summary,
Lower Duwamish Waterway Source Control Update (Dept. of Ecology, August 2007)
Lower Duwamish Contacts
Department of Ecology
City of Seattle:
US Environmental Protection Agency:
Port of Seattle: