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Programmatic Sediment Management Plan

9/26/2014: A Federal Register notice today erroneously stated the public comment period for the Lower Snake River Final Programmatic Sediment Management Plan Environmental Impact Statement (PSMP EIS) had been extended to 9/29/2014. The public comment period ended on 9/22/2014. We expect a correction will be published by EPA in the Federal Register.

Final PSMP Environmental Impact Statement Available for Public Review and Comment

Public comments due by Sept. 22, 2014 

(August 2014) The U.S. Army Corps of Engineers, Walla Walla District (Corps), invites public review and comment 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 Aug. 22, 2014, when the notice of availability is published in the Federal Register, and runs through Sept. 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, and 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.

PSMP EIS documents are available in electronic form via the links on the right side of this page. Note Draft EIS Appendix H is now incorporated with Final EIS Appendix L (CWA Section 404(b)(1) Evaluation).

Comments must be submitted or postmarked no later than Sept. 22, 2014, to be considered.  Submit comments via e-mail to psmp@usace.army.mil or via U.S. Mail to: U.S. Army Corps of Engineers, Walla Walla District, PSMP/EIS, Attn: Sandy Shelin, CENWW-PM-PD-EC, 201 North Third Avenue, Walla Walla, Washington, 99362-1876.

If you would like a compact disc (CD) version of plan documents, or to review a paper copy, contact Ms. Shelin, environmental coordinator, at 509‑527-7265, or Mr. Richard Turner, project manager, at 509-527-7625. If you have questions about the project, please contact either Ms. Shelin or Mr. Turner, or submit your questions to the e-mail address above. 

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The study area extends from the mouth of the Snake River upstream to the communities of Lewiston, Idaho, and Clarkston, Washington. It also includes the lower 2 miles of the Clearwater River, from its confluence with the Snake River in Lewiston upstream to the U.S. Highway 12 Bridge. All tributaries that significantly contribute sediment to the lower Snake River have been included in the study. See link to the study area map in upper right-hand corner.

Although the Corps does not have the authority to manage lands outside of the reservoir project boundaries, management strategies for non-Corps property have been identified and evaluated.

While site-specific locations are not addressed in the EIS, the coordination and environmental review steps required to accomplish subsequent site-specific actions are presented.


The Local Sediment Management Group (LSMG), originally formed in 2000, provides agency and stakeholder input to the U.S. Army Corps of Engineers, Walla Walla District, on sediment management within the lower Snake River drainage area.

The LSMG plays an important role in the implementation of Corps sediment management activities, and is a forum to address regional sediment issues. LSMG members include tribes plus state and federal agency representatives. Public ports within the study area also participate, as do other entities with an interest in sediment management such as  land management agencies, environmental groups, and transportation interests.


While the LSMG originally focused primarily on dredged material management, its purpose has been expanded. The LSMG now assists with the identification of sediment sources in all tributary watersheds to the lower Snake River reservoirs and with informing the group of recent studies, projects, and techniques related to sediment management in the region. This group's formation and direction is consistent with the guidance on formation of local planning groups provided by the National Dredging Team (NDT). The LSMG will continue to develop in accordance with policies and procedures for the EPA’s Regional Dredging Team (RDT) , as referred in the April 26, 2002, policy letter jointly signed by Brigadier General David A. Fastabend (Corps of Engineers, Northwestern Division Commander) and L. John Iani (EPA, Region 10, Administrator).  The LSMG charter defines the roles and responsibilities of the LSMG members and set up the group structure.