Ririe Dam and Reservoir Proposed Interim Operations Final Environmental Assessment

Ririe Dam and ReservoirThe Bureau of Reclamation issued the Final Environmental Assessment (EA) and Finding of No Significant Impact (FONSI) for the proposed Winter Interim Operations at Ririe Dam and Reservoir on January 28, 2015.

Located in Bonneville County, Idaho, the Ririe Project (Project) was constructed to impound and control the waters of Willow Creek for flood control, irrigation and recreation. Constructed between 1970 and 1977 by the U.S. Army Corps of Engineers (Corps), Ririe Dam serves the principal purpose of flood control on Willow and Sand Creeks. Ririe Dam and Reservoir is approximately 15 miles northeast of Idaho Falls.

The Corps transferred operation and maintenance responsibilities to Reclamation through a memorandum of agreement in 1976. Reclamation manages the Project for multiple purposes including water storage for irrigation; the Corps is responsible for the flood control operations of the Project as required by Section 7 of the Flood Control Act of 1944.

The Draft EA was made available on September 5, 2014, to more than 150 federal, state, and local agencies, elected officials, Tribal governments, irrigation districts, interest groups, and individuals for a 30-day comment period. The Draft EA proposed to reduce Ririe Reservoir winter drawdown for a 10-year interim period to improve refill reliability and increase water availability for irrigation without increasing downstream flood risk. Comments were received from the Corps, Mitigation, Inc., Bonneville County Commissioners, Idaho Ground Water Appropriators, Inc., National Weather Service, and Natural Resources Conservation Service.

The Final EA includes two alternatives, the No-action and Alternative 1. The No-action alternative continues the practice of drafting the reservoir contents to 5,000 acre-feet below required winter flood space at the beginning of winter, so storage of natural inflows would not often encroach on the winter flood control space, and winter releases would typically not be required. Reclamation plans to move forward with Alternative 1, which would allow storage of winter inflows up to 8,000 acre-feet in the winter flood control space through the end of February. Each year, Mitigation, Inc. would have the option of signing an agreement with Reclamation prior to the beginning of winter that would activate Alternative 1, by committing to clean the channel of snow and ice in advance of any required releases, as described in the Final EA.

Hard copies or CD-ROM versions of the report may also be obtained free of charge by contacting Mr. Rich Jackson at rjackson@usbr.gov, by mail at the Bureau of Reclamation, Snake River Area Office, 230 Collins Rd., Boise, Idaho 83702, or by phone at (208) 383-2285.

Reclamation determined an EA is required under the National Environmental Policy Act in order to undertake this action. The draft EA evaluates the impacts of the proposed alternatives on the human population and the natural environment. Public input on the draft EA will assist Reclamation in making an informed decision.

01/28/2015 Finding of No Significant Impact Final Environmental Assessment Ririe Winter Storage Study PDF 15.16 MB
09/05/2014 News Release: Reclamation Seeks Public Comment on Proposed Winter Interim Operations at Ririe Dam and Reservoir
09/2014 Ririe Dam & Reservoir Proposed Interim Winter Operations Factsheet PDF 425 kb
09/2014 Draft Environmental Assessment Ririe Winter Storage Study PDF 19.12 mb
12/09/2013 Media Advisory: Public Open House for Comments on Interim Winter Operation Alternatives at Ririe Dam and Reservoir
12/05/2013 Factsheet: Ririe Dam and Reservoir Proposed Interim Operations PDF 249 kb
11/26/2015 News Release: Reclamation Hosts Open House for Additional Comments on Interim Winter Operation Alternatives at Ririe Dam and Reservoir
01/11/2011 Fact Sheet: Ririe Dam and Reservoir Proposed Interim Operations PDF 108 kb
01/05/2011 News Release: Reclamation Hosts Public Meeting on Ririe Reservoir and Dam Proposed Interim Operations
12/15/2010 Ririe Dam and Reservoir Area Map


Rich Jackson
Natural Resource Specialist
(208) 383-2285 ririeea@usbr.gov

Bureau of Reclamation
470 22nd Street
Heyburn, ID 83336

Last Updated: 4/19/23