In accordance with the National Environmental Policy Act of 1969 ^[1] and the Federal Energy Regulatory Commission's (Commission) regulations, 18 CFR part 380, the Office of Energy Projects has reviewed Idaho Power Company's (Idaho Power) application for a new license to continue to operate and maintain the Hells Canyon Hydroelectric Project No. 1971 (project) and has prepared a final supplemental environmental impact statement (SEIS) for the project.^[2] The project is located on the Snake River in Washington and Adams Counties, Idaho, and Wallowa, Malheur, and Baker Counties, Oregon and occupies a total of about 5,270 acres of federal land administered by the U.S. Bureau of Land Management and the U.S. Department of Agriculture, Forest Service (Forest Service). The Hells Canyon Project consists of three developments (dams, reservoirs, and powerhouses) on the segment of the Snake River forming the border between Idaho and Oregon. The three developments are Brownlee, Oxbow, and Hells Canyon, which combined provide 1,222.3 megawatts of power generating capacity and an average of 5,571,005 megawatt-hours of electricity annually.

On August 31, 2007, Commission staff issued a final environmental impact statement (EIS) for the proposed relicensing of the project. On December 30, 2019, Idaho Power filed an Offer of Settlement and Stipulation and Implementation Agreement (2019 Settlement), resolving disputed issues related to spring Chinook salmon and summer steelhead passage and reintroduction with the states of Oregon and Idaho in the context of their respective water quality certifications for the project under section 401 of the Clean Water Act (401 certifications). Pursuant to the 2019 Settlement, the states of Oregon and Idaho each issued 401 certifications for the project on May 24, 2019. On July 8, 2020, Idaho Power filed a supplement to its license application that included new and revised environmental measures proposed under the 2019 Settlement, refinements to the proposed action, and new information on project-affected resources. On October 14, 2020, pursuant to the Endangered Species Act (ESA), Idaho Power filed revised draft biological assessments for species managed by the U.S. Fish and Wildlife Service and the National Marine Fisheries Service, which were subsequently revised again in July 1 and July 16, 2025, filings. On October 23, 2024, Idaho Power filed a settlement agreement on behalf of itself and the Forest Service (2024 Settlement), resolving between the parties the appropriate terms and conditions pursuant to section 4(e) of the Federal Power Act to be incorporated into any new license issued for the project for the protection and utilization of federal lands administered by the Forest Service.

In accordance with Commission staff's June 13, 2022 notice of intent to prepare a draft and final SEIS, staff has prepared this final SEIS to supplement the final EIS with analyses of the new and revised proposed measures and mandatory conditions ( i.e., modified 4(e) conditions and 401 certification conditions) filed subsequent to the issuance of the final EIS, as well as the potential effects of the new and revised measures on federally listed species and their designated critical habitats.

The final SEIS contains an analysis of Idaho Power's proposal and the alternatives for relicensing the project. The final SEIS documents the views of governmental agencies, non-governmental organizations, affected Tribes, the public, the license applicant, and Commission staff.

The final SEIS may be viewed on the Commission's website at http://www.ferc.gov under the “eLibrary” link. Enter the docket number excluding the last three digits in the docket number field to access the document. For assistance, contact FERC Online Support at FERCOnlineSupport@ferc.gov, (866) 208-3676 (toll free), or (202) 502-8659 (TTY).

You may also register online at https://ferconline.ferc.gov/​FERCOnline.aspx to be notified via email of new filings and issuances related to this or other pending projects. For assistance, contact FERC Online Support. ( printed page 57592)

For public inquiries and assistance with making filings such as interventions, comments, or requests for rehearing, contact the Office of Public Participation at (202) 502-6595 or OPP@ferc.gov.

For further information, contact Aaron Liberty, the Commission's relicensing coordinator for the project, at (202) 502-6862 or aaron.liberty@ferc.gov.

(Authority: 18 CFR 2.1)