LEWISTON, Idaho (AP) — The U.S. Army Corps of Engineers is delaying its plan to dredge and deepen the navigation channel at the ports of Lewiston and Clarkston until December 2014 at the earliest. The agency had hoped to complete its environmental reviews in time to allow dredging this winter.

But The Lewiston Tribune reports the complexity of technical and environmental reviews have stalled the project. Lewiston is the most inland seaport on the West Coast, and the port area needs occasional dredging because sand and silt build up near the confluence of the Snake and Clearwater rivers.

It was last dredged in 2006. Environmental groups oppose the dredging, and say cargo could be shipped by truck or rail.