The U.S. Army Corps of Engineers is seeking public comments on its proposal to dump dredge spoils in the lower Snake River, even though the agency hasn't approved dredging there.

The corps has outlined a number of actions it wants to take to manage the accumulation of sediment in the river, including removing about 470,000 cubic yards of sediment from the navigation channel near Lewiston. Those actions are outlined in its draft programmatic sediment management plan. The document, which is more than 1,000 pages, is open to public review through March 26.

But on Monday, the corps announced that it would simultaneously begin taking comments on the potential effects to water quality of dumping the dredge spoils near Knoxway Canyon, about 23 miles downstream of Lewiston. The analysis is required under the Clean Water Act.

The public comment period on that process, and a separate Washington Department of Ecology effort to analyze the effect spoil disposal will have on the state's water quality standards, will end April 11.

Corps spokesman Bruce Henrickson at Walla Walla said the simultaneous comment periods are necessary if the agency is to keep on pace to dredge the river next winter. To do so, it needs to make a decision and have all the environmental reviews completed in time to seek bids on the work. But Henrickson said the agency is not presupposing the outcome of the public comment or environmental review processes.

"The public does have input right now. We have not decided anything," he said. "If we decide to move ahead with dredging, and that is a big if, we need to have a signed record of decision this summer."

Dredging and other work in streams and rivers occupied by threatened and endangered salmon and steelhead must occur between Dec. 15 and March 1, when neither adults nor juveniles are migrating. The corps is proposing to use the dredge spoils to create shallow water habitat for juvenile salmon and steelhead. Dredging would restore the navigation channel to a depth of 14 feet and a width of 250 feet. The plan also calls for a smaller amount of dredging at the ports of Lewiston and Clarkston.

The corps has also outlined a number of other actions it could take to manage sediment, including levee raising, a system of spur dikes designed to keep sediment suspended longer, reservoir drawdown, and upstream erosion control. Dredging is the only action outlined in the draft plan that the agency said needs to happen in the near future.

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