Corps completes dredging on river channels

A crane on the Heidi Renee dredges sediment from the Clearwater River.

The American Construction Company, Inc., dredges on the Clearwater River.

The U.S. Army Corps of Engineers last week completed maintenance dredging of problem areas of the navigation channel and two port berthing areas in the Snake and Clearwater rivers. Dredging was performed to meet a current immediate need to re-establish the channel to its authorized dimensions, 250 feet wide by 14 feet deep at minimum operating pool elevation. Dredging began Jan. 12.

Maintenance dredging was completed during the annual winter work window, Dec. 15 through Feb. 28, when salmonid fish are less likely to be present in the river.

Maintenance dredging last occurred in the lower Snake River navigation channel in the winter of 2005-2006.

“Navigation on the lower Snake River is now safer,” said Lt. Col. Timothy Vail, Walla Walla District Commander. “We considered potential alternatives, determined dredging was the only effective short-term tool for addressing problem sediment that had accumulated to the point of interfering with navigation and successfully completed maintenance dredging during the designated winter work window.”

Dredging initially took place at the downstream lock approach of Ice Harbor Dam, then later on the Lower Granite lock and dam pool at the confluence of the Snake and Clearwater rivers in the Lewiston-Clarkston area. Work included the Port of Lewiston and Port of Clarkston berthing areas. The ports obtained their own dredging permits and paid for dredging of their berthing areas.

Dredged materials were used to construct additional shallow-water fish habitat near Knoxway Canyon about 23 miles downstream of Clarkston, close to Lower Granite Dam.