Final Supplemental EIS for Grays Harbor Navigation Improvement completed

Published July 3, 2014

A supplemental Environmental Impact Statement on the U.S. Army Corps of Engineers’ Grays Harbor Navigation Improvement Project will be available for review and comment July 11-Aug. 11, 2014.

The Corps has produced a limited reevaluation report and supplemental EIS resulting from a General Investigation of dredging the federal navigation channel to its legislatively authorized depth of -38 feet. 

The reevaluation report, supplemental EIS and appendices are available to review on line through Seattle District’s main website: by clicking on “Environmental Documents” under the “Open Public Comment Period” column.  The documents are also accessible on the Grays Harbor Navigation Improvement page at: 

The Corps is accepting public comments on the limited reevaluation report and supplemental EIS for a 30-day period beginning July 11 and ending Aug. 11.  Comments can be sent via email to: or through the mail to Leah Wickstrom, CENWS-PM-CP, PO Box 3755, Seattle, WA 98124-3755.



The Grays Harbor federal navigation deep draft channel is 250 feet wide at Cosmopolis, increasing to 1,000 feet over the Bar at the mouth of Grays Harbor. The currently maintained channel depth is -36 feet Mean Lower Low Water (MLLW) from the South Reach to the Cow Point Reach, where Port of Grays Harbor Terminal 4 is located. The channel then decreases to -32 feet MLLW through Cosmopolis. 

The Corps investigated the feasibility of dredging the channel from the South Reach upstream to Cow Point to its fully legislatively authorized depth of -38 feet MLLW. This project covers approximately 14.5 miles of the 27.5 mile channel.  Deepening of the relevant portion of the Grays Harbor navigation channel to -38 feet MLLW was authorized by Congress in 1986, but a 1989 economic evaluation found that dredging only to -36 feet MLLW was economically justified at that time. Through updated economic and environmental analysis the present study has evaluated implementing the previously authorized -38-foot depth through a Limited Reevaluation Report and a Supplemental Environmental Impact Statement (EIS), building on the original 1982 EIS and its 1989 Supplement.

The potential two-foot deepening being evaluated is neither designed nor intended to facilitate access for any new vessel classes or commodity types that could not currently utilize Port facilities.

The Corps maintains the waterway now by dredging the deep draft channel annually at an average cost of $9 million, removing an average annual volume of about 1.7 million cubic yards of material. 

For additional information about Grays Harbor Navigation visit our website at:  and click on “Grays Harbor Navigation” under “Most Requested.”

Public Affairs Office

Release no. 14-033