The U.S. Army Corps of Engineers’ Walla Walla District on Friday awarded a $6.7 million contract for maintenance dredging of the lower Snake River federal navigation channel and associated berthing areas at the Ports of Lewiston, Idaho, and Clarkston, Wash. The contract was awarded to American Construction Co., Inc., of Tacoma, Wash., as a small business set-aside contract.
The maintenance dredging is planned to occur during the upcoming annual “winter in-water work window,” Dec. 15 to Feb. 28, when salmonid fish are less likely to be present in the river.
Prior to this contract award, the Corps on Friday, Nov. 14, finalized the long-term, comprehensive Lower Snake River Programmatic Sediment Management Plan (PSMP) after review and consideration of extensive public comments on a PSMP Final Environmental Impact Statement (FEIS).
As previously announced, the Corps’ Northwestern Division Commander, Brig. Gen. John S. Kem, signed two separate Records of Decision (RODs) on Friday for the PSMP and the current “immediate need” action (dredging), to reestablish the congressionally authorized dimensions of the Lower Snake River federal navigation channel.
The RODs were based on consideration of reasonable alternatives and evaluation of potential environmental effects contained in the FEIS. Signing of the RODs marked completion of the Walla Walla District National Environmental Policy Act (NEPA) review process.
This planned dredging action is consistent with the Corps’ PSMP to manage sediment accumulation that interferes with existing authorized purposes of the Corps’ lower Snake River dam and reservoir projects—navigation, recreation, fish and wildlife conservation, and flow conveyance. The PSMP specifies “immediate needs” and “future needs” triggers for Corps action. Dredging is one measure in a “toolbox” of measures for addressing problem sediment in the river.
It is the only effective short-term tool available for maintaining the federal navigation channel to authorized dimensions of 250 feet wide by 14 feet deep at minimum operating pool (MOP).
There is a current “immediate need” to reestablish the congressionally authorized dimensions of the Lower Snake River federal navigation channel. Maintenance dredging last occurred in the lower Snake River navigation channel in the winter of 2005-2006. Sediment accumulation has encroached on certain areas of the federal navigation channel and port berthing areas.
The contract specifies dredging of about 400,000 cubic yards in four areas:
1) the navigation lock approach at Ice Harbor Dam;
2) confluence of the Snake and Clearwater rivers;
3) Port of Lewiston berthing area; and
4) Port of Clarkston berthing area.
The Ports are funding the berthing area maintenance dredging and all associated administrative costs. The Corps plans to use the dredged material to create shallow-water habitat for juvenile salmon at Snake River mile 116, located just upstream of Knoxway Canyon and 23 miles downstream of Clarkston.
Additionally, the Corps on Friday issued Clean Water Act Section 404 and Rivers and Harbors Act Section 10 Department of the Army permits to the Port of Lewiston and the Port of Clarkston for the ancillary/related berthing area maintenance dredging. Those berthing areas are adjacent to the federal navigation channel. The PSMP Final EIS considered potential environmental effects for the berthing area maintenance dredging.