SEATTLE DISTRICT

Home
Home > Missions > Civil Works > Dredging

Dredged Material Management Office

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.  The DMMP has no direct regulatory authority; it serves to streamline the process for dredged material evaluation and management.

The DMMP reviews proposed dredging in Washington State:  in Puget Sound, Grays Harbor & Willapa Bay, the Washington side of the lower Columbia River (with the exception of port districts); and other marine and freshwater locations.

This website is updated frequently with meeting announcements, program information and decision documents. Please check back frequently.


Contact:  PO Box 3755, Seattle WA 98124-3755     DMMOteam@usace.army.mil     206-764-6083 / -6550 / -6945 / -6713

Popular Pages

News and Updates

The 29th SMARM will be held on Wednesday, May 3, 2017.  We'll be changing it up a little this year, with a focus on bioaccumulation in Puget Sound.  For more information check the SMARM page.  Hope to see you there!


Always refer to the latest version of the DMMP User Manual when planning projects!  Updated annually, most recently in August 2016, it keeps current methods, guidance and program modifications all in one place.  Next update expected Fall 2017.


For more information on DMMP disposal site locations and monitoring see the Disposal page.

Mukilteo dredge

About Us

Collapse All Expand All
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.
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.

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.

The multi-agency, multi-state RSET (Regional Sediment Evaluation Team) is an umbrella organization whose role is to provide a consistent regional framework for the evaluation of dredged material.  RSET developed the Sediment Evaluation Framework (SEF 2009) 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.  Regional sediment evaluation policy questions and recommended modifications to the SEF should be directed to the RSET Lead

Both the DMMP User Manual and the Sediment Evaluation Framework for the Pacific Northwest are used in the Northwest for evaluating the suitability of dredged material for unconfined aquatic disposal. 

The interagency DMMP covers most projects in Washington State:  all Puget Sound and coastal Washington projects should reference the DMMP User Manual and related guidance when developing characterization plans. Projects on the Washington side of the Columbia River--EXCEPT for Washington public ports--should also use the DMMP guidance.  Questions regarding sediment evaluation for DMMP projects should be directed to the DMMO team.

The Portland Sediment Evaluation Team (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 PSET evaluates dredging and habitat restoration projects in the Portland District, including dredging projects proposed by the Washington public ports on the Columbia River. 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.