The U.S. Army Corps of Engineers, Walla Walla District, has invited public review and comments on the Lower Snake River Final Programmatic Sediment Management Plan and Environmental Impact Statement (PSMP EIS).
The PSMP EIS comment period is planned to open August 22, 2014, when the notice of availability is published in the Federal Register, and runs through September 22, 2014.
The Corps is proposing to adopt and implement a long-term, programmatic plan for managing sediment accumulation that interferes with existing authorized purposes of the Corps’ four lower Snake River dam and reservoir projects (Ice Harbor, Lower Monumental, Little Goose, and Lower Granite) in southeastern Washington and north central Idaho. Authorized project purposes include navigation, recreation, fish and wildlife conservation, and flow conveyance.
The Final PSMP EIS identified and evaluated the potential environmental effects of a range of sediment management alternatives. The EIS identified Alternative 7 “Comprehensive (Full System and Sediment Management Measures)” as the preferred alternative, which provides a “toolbox” of measures for addressing problem sediment. This alternative includes dredging and dredged material management along with other sediment and system management measures, and provides the Corps with a complete “toolbox” for addressing sediment that interferes with the authorized purposes of the projects.
The Corps is also proposing a current “immediate need” maintenance dredging action, consistent with the PSMP, to re-establish certain areas of the federal navigation channel to congressionally authorized dimensions of 14 feet deep by 250 feet wide at minimum operating pool (MOP). Maintenance dredging in the lower Snake River navigation channel last occurred in the winter of 2005-2006. The Corps proposes to perform the dredging during the first available winter “in-water work window,” Dec. 15 to Feb. 28, contingent upon signing of a record of decision (ROD) for the PSMP.
The Corps proposes to perform maintenance dredging activities at two locations:
1) the downstream navigation lock approach at Ice Harbor Dam;
2) the confluence of the Snake and Clearwater rivers in Lower Granite reservoir.
The Corps proposes to use the dredged material to create shallow-water habitat for juvenile salmon at Snake River mile 116, just upstream of Knoxway Canyon and 23 miles downstream of Clarkston.
The PSMP EIS also considered potential environmental effects for Clean Water Act Section 404 and Rivers and Harbors Act Section 10 permits for ancillary/related berthing area maintenance dredging by the Ports of Lewiston and Clarkston, adjacent to the federal navigation channel.
The Ports will fund the berthing area maintenance and all associated administrative and environmental review costs. The Corps’ Regulatory Division will make final decisions on ports’ permit applications.
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Press Release, August 15, 2014