Lower Duwamish Waterway
What is source control?
Illustration of potential pollution pathways.
Source control is the process of finding and then stopping or reducing releases
of pollution to waterway sediments. The point of source control is to minimize
the keep sediments from becoming polluted again after being cleaned up. Finding
and controlling sources is difficult and even with aggressive source control,
some recontamination may occur.
The near-term goal is to control sources sufficiently to allow active
in‑waterway remediation to start, minimizing the likelihood that sediments will
be recontaminated at levels that trigger additional active in-waterway
The long-term goal, after the sediment remedy is in place, is to minimize the
risk of recontaminating sediments above the sediment cleanup standards
established in the Record of Decision.
Source Control Strategy:
The Source Control Strategy describes the goals, priorities and process used to
address source control work. The purpose of this document is to provide the
framework and process for identifying source control issues and implementing
effective controls for the Lower Duwamish Waterway. The basic source control
strategy for the LDW site is to identify and manage sources of chemicals to site
sediments in coordination with sediment cleanups.
Source Control Work Group
Ecology leads the interagency Source Control Work Group (SCWG). The SCWG
shares information, discusses strategy, develops action plans, implements
source control measures, and tracks progress. The SCWG includes Ecology, the
City of Seattle, King County, Port of Seattle, and EPA.
The table below shows each agency's role in the SCWG.
Ø Ecology: Lead
for source control at properties that discharge directly to the waterway and
for source control work at upland contaminated properties;
Ø City of Seattle:
Lead for source control within their storm drain system;
Ø King County:
Lead for source control for discharges to wastewater or combined wastewater
and storm water systems;
Ø EPA: Lead for
Boeing Plant 2, Terminal 117, Slip 4 sediments, and Rhone/Poulenc cleanup
sites; provides technical assistance, source control coordination with EPA
sediment investigation and cleanup activities.
Source Control Implementation Plans
As the lead agency for Source Control, Ecology has asked the city of Seattle,
King County, and EPA to develop agency-specific implementation plans. The intent
of the implementation plans is to set each agency’s priorities for source
control for a near-term (5 years) and to establish long-term expectations for
source control activities during and following construction of the in-waterway
cleanup under the ROD. These plans will be considered part of the Source Control
Strategy following their completion.
City of Seattle Implementation Plan
The land area around the Lower Duwamish Waterway (LDWW) is divided into
24 sub-basins (or source control areas) based on the pathways that storm
runoff can take as it drains into the waterway.
Source Control Status Reports:
These reports summarize source control activities conducted by the Lower
Duwamish Waterway (LDW) Source Control Work Group. They provide an
overview of the LDW site, the strategy for controlling sources of pollutants to
the LDW, the process for developing Source Control Action Plans (SCAPs), the
methods and process for implementing the SCAPs, issues associated with permitted
discharges, and a summary of source control actions during the period of the
More helpful information...
What Can You Do to Help Prevent Pollution from Entering the Duwamish?
This page last updated January 11, 2017