Dredged Material Management Office (DMMO)


The Seattle District DMMO is the main point of contact for the interagency Dredged Material Management Program (DMMP). The DMMP brings together agencies with roles in management and regulation of dredged material to streamline testing and decision-making.  Together the DMMP agencies manage a network of multiuser open-water disposal sites in Washington State.



Contact the DMMO

Seattle District (CENWS)
Dredged Material Management Office
4735 E. Marginal Way S. Bldg. 1202
Seattle, WA 98134-2388

USACE Seattle

USACE Seattle

News and Updates

2024 Sediment Management Annual Review Meeting  

The 36th Sediment Management Annual Review Meeting was held in-person and virtually on May 8th, 2024 at the USACE Seattle District Headquarters at Federal Center South in Seattle, WA.   Post-meeting information, including PDFs of all presentations and clarification papers, is available on the SMARM page.  

Email CENWS-DMMOTeam@usace.army.mil to be added or removed from the SMARM mailing list.  


Updated Puget Sound SRM Acceptance Criteria and Guidance Document

The Puget Sound Sediment Reference Material (PS-SRM) guidance document has been updated and the PS-SRM acceptance limits have been recalculated.  The new documents are available on the Puget Sound SRM page.   


Dredge Year 2022-2023 Biennial Report - Now Available!

The Dredged Material Management Program (DMMP) has finalized the DY22-23 Biennial Report, which outlines all project evaluation and disposal activities for the period of June 16, 2021 - June 15, 2023.  The report is available for download at the bottom of the Reports, ESA and History page. 


2021 DMMP User Manual

The Dredged Material Management Program (DMMP) has finalized the 2021 Dredged Material Evaluation and Disposal Procedures User Manual (User Manual).    The procedures in the 2021 User Manual replace guidance in all previous versions.  The updates apply to all projects in Puget Sound, on the Washington Coast, the north side of the Columbia River, and all other water bodies within the State of Washington.  The 2021 User Manual is available for download  on the User Manual page. 




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 What is the Dredged Material Management Program?
The Dredged Material Management Program (DMMP) consists of four agencies that work collaboratively to make sure that material proposed for dredging in Washington State is appropriately tested and managed. The DMMP agencies are the U.S. Army Corps of Engineers, Seattle District (USACE); the U.S. Environmental Protection Agency, Region 10 (EPA); the Washington Department of Ecology (Ecology); and the Washington State Department of Natural Resources (DNR).

The federal government, ports, marinas and other entities dredge to maintain navigational waterways and berth depths when those areas are filled in by natural sediment deposition. The DMMP agencies oversee testing for contaminants to determine what material can be disposed of at open-water disposal sites. The state-owned sites are managed by DNR. The DMMP does not manage contaminated sediment cleanups--those are managed by cleanup programs within Ecology and EPA.
 How much dredging is done and why is it important?
Dredging affects the lives of nearly every Washington State citizen and visitor.  Maintenance and navigation dredging is done frequently in harbor areas, ports and marinas. These areas naturally silt in. Dredging is performed to maintain the depths needed for boats to operate, and to develop new areas or achieve increased depths for boat access. A significant component of Washington's economy depends on navigation and commerce, which in turn depends on dredging the state's waterways; between 2000 and 2015, over 50 million cubic yards of dredged material have been dredged and disposed of at the open-water disposal sites.
 Where is dredged material disposed?

An extensive analytical, public process was used to define open-water sites for dredged material disposal, and to define the guidelines for dredged material that can be disposed at these sites. There are two types of sites:  dispersive and non-dispersive.

Dredged material placed at non-dispersive sites remains on-site and is the subject of long-term monitoring.  Non-dispersive sites are managed to allow minor adverse effects such as sub-lethal effects to some species after long-term exposure.

Dredged material placed at dispersive sites--which are located in areas with strong tidal currents--disperses quickly. No adverse effects are allowed at dispersive sites, so dredged material must meet more stringent evaluation guidelines to be eligible for disposal at these sites.

There are eight dredged material disposal sites around Puget Sound (three dispersive and five non-dispersive) and two dispersive estuarine sites each in Grays Harbor and Willapa Bay. The DMMP agencies collectively evaluate the suitability of dredged material for disposal at these sites. As owner of the state's aquatic lands, DNR manages the disposal sites and is responsible for environmental monitoring of all nondispersive disposal sites.

 What is the Regional Sediment Management Team (RSET)?

RSET (Regional Sediment Evaluation Team) is a multi-agency, multi-state umbrella organization whose role is to provide a consistent regional framework for the evaluation of dredged material in the Pacific Northwest.  RSET developed the Sediment Evaluation Framework (SEF 2016) as a guide to regional sediment testing. The RSET is tasked with maintaining and updating the SEF based on customer feedback and changes in science and national policy. 

The DMMP agencies ensure that the content of the DMMP User Manual is aligned with the regional SEF through agency participation in regular RSET meetings and involvement in SEF updates.

 Should we use the DMMP User Manual or the SEF?

The DMMP User Manual is the implementation manual for dredged material evaluations in the state of Washington.  For projects within the geographic jurisdiction of the DMMP, use the DMMP User Manual for dredging project evaluations.

The DMMP User Manual applies to projects in Puget Sound, on the Washington Coast, for non-port projects on the Washington side of the Columbia River, and to all other water bodies within the state of Washington.  Questions regarding sediment evaluation for DMMP projects should be directed to the DMMO team.

Port projects on the Washington side of the Columbia and ALL projects on the Oregon side are evaluated by the Portland Sediment Evaluation Team (PSET). PSET is headquartered at the USACE Portland District, and functions similarly to the DMMP for Oregon projects. The PSET agencies include the Portland District, Environmental Protection Agency, Oregon Department of Environmental Quality, Washington Department of Ecology, U.S. Fish and Wildlife Service, and National Marine Fisheries Service.  The SEF should be used for Portland District projects.  Questions regarding dredged material testing and evaluation procedures for Portland District projects (including Corps dredging permits) should be directed to the PSET Lead.