The U.S. Army Corps of Engineers, Walla Walla District, and its dredging contractor American Construction Company plan to begin lower Snake River dredging on or about Monday, January 12, at the downstream lock approach of Ice Harbor Dam, plus at the confluence of the Snake-Clearwater rivers in the Lewiston-Clarkston area.
Dredging vessels and equipment will also be moving between the dredging locations and the dredged material placement site (River Mile 116) during this time. The dredging is likely to involve a 24-hour-a-day operation.
Starting today, prior to the start of dredging, the contractor will be placing water quality monitoring buoys both downstream and upstream at the dredging locations. Monitoring buoys measure water turbidity levels.
River mariners are urged to be cautious around dredging vessels and equipment. In accordance with standard procedures, the Corps has also issued a notice to the navigation industry announcing the presence of dredging vessels and equipment in the lower Snake River between today and February 28.
Vessels planning to lock through Ice Harbor Dam during this time period must coordinate in advance of lockage with the Ice Harbor Control Room at (509) 543-3231 or navigation channel 14. This allows the contractor to move dredging vessels or equipment to accommodate vessel lockage.
The Ice Harbor lock is planned to return to normal operations by 5 p.m. on Thursday, January 15.
Maintenance dredging last occurred in the lower Snake River navigation channel in the winter of 2005-2006. Sediment accumulation has since encroached on certain areas of the federal navigation channel and related port berthing areas.