US Army Corps of Engineers
Seattle District Website

Tacoma Harbor Navigation Improvement Study


The purpose of this study is to investigate navigation improvements to the Blair Waterway in the Port of Tacoma in Washington to achieve transportation cost savings (increased economic efficiencies) for larger vessels calling at the port.

The Blair Waterway is currently authorized to -51 feet. In the past decade, ships calling at the Northwest Seaport Alliance (NWSA) have increased in size and draft at a dramatic pace. The larger vessels have draft requirements deeper than -51 feet when fully laden, and therefore will face tidal delays and other transportation inefficiencies when arriving and departing the waterways. The NWSA is a rapidly expanding major port, ranking as the 28th largest U.S. port in terms of total tonnage, and the fourth largest container gateway.

The draft feasibility study determined there is a federal interest in participating in a cost-shared modification of the existing Tacoma Harbor project in the interest of navigation improvements and water resources development opportunities. The draft feasibility report and Environmental Assessment (EA) identify a tentatively selected plan to deepen the existing channel to an authorized project depth of -57 feet MLLW, expand channel widths ranging from 450 feet to 865 feet, and expand the turning basin boundary to a diameter of 1,935 feet. Under the least cost disposal option, approximately 2.4 million cubic yards (cy) of dredged material would be placed in the Dredged Material Management Program (DMMP) Commencement Bay open water disposal site and approximately 392,000 cy would be placed at an upland facility. In addition, the Saltchuk site, located northeast of the Blair Waterway, is a potential location for beneficial use of dredged material for environmental benefits. Although not the least-cost disposal option, the tentatively selected plan includes additional evaluation of beneficial use of approximately 1.85 million cy of material at the Saltchuk site based on preliminary analysis and results. Beneficial use of dredged material at Saltchuk would reduce the amount of dredged material going to the DMMP Commencement Bay site by 1.85 million cy.

The feasibility cost sharing agreement between the U.S. Army Corps of Engineers and the Port of Tacoma was signed August 21, 2018. An alternatives milestone meeting held in November 2018 confirmed alternatives to be evaluated during the study, including full channel deepening (-52 feet Mean Lower Low Water (MLLW) through -58 feet MLLW) and channel segments defined by container terminal location. The draft feasibility report and EA and appendices were made available to review online December 18, 2019 - February 16, 2020 on this web page.

The U.S. Army Corps of Engineers issued notice December 21, 2018, of plans to prepare, pursuant to the National Environmental Policy Act, an environmental assessment for the Tacoma Harbor, Washington, Navigation Improvement Project.  The purpose of this Public Notice was to solicit comments during an open comment period through February 21, 2019, from interested persons, groups and agencies on the environmental impact of the proposal and issues for consideration in the EA.

The Corps is accepting public comments on the draft report and EA for a 60-day comment period beginning December 18, 2019, through February 16, 2020. Comments can be sent via email to: or through the mail ATTN: U.S. Army Corps of Engineers, Seattle District, CENWS-PMP, PO Box 3755, Seattle, WA 98124-3755. All email comments must reach the Corps no later than the expiration date of the public comment period, and all comments submitted through the U.S. Postal Service must be post marked by the expiration date to ensure consideration.