Corps, contractor begin at two Snake River sites

U.S. Army Corps of Engineers, Walla Walla District, and its dredging contractor American Construction Company, began lower Snake River dredging Monday 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.

The contractor placed 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 now and Feb. 28.

Vessels planning to lock through Ice Harbor Dam during this time must coordinate in advance of lockage with the Ice Harbor Control Room. 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. today.

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 navigation channel and related berthing areas.