My Basin photo identifier

My Basin

Green-Duwamish Watershed Pollutant Loading Assessment

Pollutants entering the Duwamish River

The Department of Ecology (Ecology) and the U.S. Environmental Protection Agency (EPA) worked together for many years to identify, clean-up, and control sources of pollution to the lower 5.5 miles of the Green-Duwamish River, also known as the Lower Duwamish Waterway (LDW). Ecology and EPA have worked together in the LDW since 2001 when the site was added to EPA’s National Superfund Priorities List. In 2012 the Ecology and EPA initiated a comprehensive pollutant loading assessment (PLA) of the entire watershed to protect human health and the environment throughout the Green and Duwamish watershed.

Pollutant Loading Assessment Modeling Tool graphic

The PLA is needed to protect and improve the effectiveness of EPA’s Lower Duwamish in-waterway cleanup by identifying upstream pollution sources as well as strategies to reduce those sources. Existing sediment data and models completed for LDW cleanup studies indicate that LDW sediments may still exceed target levels after cleanup because of pollutant concentrations in sediment coming from upstream.

Project cooperators and phasing

Ecology and the EPA are cooperatively developing the PLA with the participation of a technical advisory committee (TAC) made up of technical staff from public agencies or quasi-governmental groups and feedback from the Interested Parties group made up of agency, business, nonprofit groups, and the general public. Ecology and EPA participated in meetings with the PLA-TAC and the Interested Parties from 2014 through July 2015. In the meetings Ecology and EPA solicited TAC input on existing water quality monitoring data, modeling parameter selection, modeling boundaries, and the overall technical direction. Summaries, agendas, and presentations for these first meetings are found at TAC and Interested Parties Meetings 2014 – 2015.

Ecology and EPA expect the PLA project to be a long term project phased over many years. Presently, the project is working on developing a hydrologic Quality Assurance Project Plan (QAPP) database development and assessment, and a hydrologic model. As technical work advances, Ecology and EPA will reconvene TAC and Interested Parties meetings. Meetings dates, times, and agendas will be posted on this website. Project documents will be posted on this website as they become available.

Project documents


Technical Advisory Committee (TAC) meetings

Committee members

This website will be updated periodically with meeting information including specific dates and times.


Meeting #9
March 15, 2017

Tukwila Community Center
Banquet Hall
12424 - 42nd Avenue South
Tukwila, WA 98168
Directions to the Center

9 a.m. - 11:30 a.m.

Meeting 10


Meeting #7
April 6, 2016

Meeting #8
October 5, 2016


Interested Parties meeting

Frequency, logistics, and communication

Participation in the Interested Parties group is open to all stakeholders and members of the public. Interested Parties group meetings and specific invitations will be extended to the TAC member organizations, as well as those already participating with the group, to ensure they are aware of the meeting. The Interested Parties group meets less frequently than the TAC. The next meeting will continue the established process for project update and participation.

Contact Joan Nolan at 425-649-4425 to be placed on the Interested Parties mailing list for direct meeting notifications. Also, the public is urged to use this website to find updated information on logistics to attend Interested Parties meetings at will.

Meeting schedule

Meeting #2
March 15, 2017

Tukwila Community Center
Banquet Hall
12424 - 42nd Avenue South
Tukwila, WA 98168
Directions to the Center

1 p.m. - 4 p.m.


Joan Nolan,, 425-649-4425

Back to top of page

Last updated March 2017