The U.S. Army Corps of Engineers is investigating the feasibility of deepening the federal navigation deep-draft channel in Grays Harbor from the currently maintained depth of -36 feet MLLW to the fully authorized depth of -38 feet MLLW. The deepening would occur from the South Reach upstream to Cow Point Reach where the Port of Grays Harbor Terminal 4 is located. The Grays Harbor Navigation Improvement Project would deepen approximately 14.5 miles of the 27.5-mile channel.
Currently, the Corps removes an average of 1.2 million cubic yards of sediment annually from the channel. The dredged material is disposed of at various approved disposal sites, including open-water disposal at the Point Chehalis, South Beach, South Jetty, and Southwest disposal sites, as well as beneficial use for beach nourishment at Half Moon Bay. Deepening the navigation channel to -38 feet MLLW is estimated to require the initial removal of approximately 1.8 million cubic yards, and would result in removing approximately ten percent more material during annual maintenance dredging. The Corps anticipates continuing to dispose of maintenance dredged material at the same disposal sites during and after implementation of the Proposed Project.
The Grays Harbor Navigation Improvement Project is located 50 miles west of Olympia on the central coast of Washington. The cities of Aberdeen, Hoquiam, Ocean Shores, and Westport surround Grays Harbor. Based on a General Design Memorandum dated February 1989, the deep draft channel was deepened to -36 feet mean lower low water (MLLW), two feet less than the fully-authorized depth of -38 feet MLLW. The Port of Grays Harbor has requested deepening the channel the additional two feet to better accommodate current vessel traffic for existing Port tenants and commodities.
The purpose of the Proposed Project is to improve the efficiency of deep-draft vessel navigation in Grays Harbor. The Proposed Project is needed to alleviate large vessel restrictions imposed by the insufficient channel depths. Ship transportation in the existing upstream channel is limited by depth. Current depths are inadequate to accommodate vessels with drafts exceeding -36 feet MLLW.