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In accordance with Section 401 of the federal Clean Water Act, the Wyoming Department of Environmental Quality (WDEQ) has received a request from Black Canyon Hydro, LLC for State certification of a Federal Energy Regulatory Commission (FERC) hydropower license and U.S. Army Corps of Engineers (USACE) Individual dredge and fill permit for discharges to Seminoe Reservoir near Rawlins, Wyoming associated with the Seminoe Pumped Storage Project. The project is a 972-megawatt pumped hydro energy storage facility that involves the construction of a new upper reservoir near Seminoe Reservoir along with a water conveyance and maintenance tunnel system, underground powerhouse, access bridge, and transmission corridor. Normal project operations would involve cycling approximately 10,800 acre-feet of stored water between Seminoe Reservoir and the new upper reservoir to generate power.
Discharges of dredged or fill material during construction will affect 0.16 acres of Kortes Reservoir (for the access bridge), 2.0 acres of Seminoe Reservoir (for the inlet-outlet structure), and 1.48 acres of wetland (for the upper reservoir). To minimize impacts to surface water quality, best management practices, including installation of a sediment curtain and a bubble wall around the inlet-outlet construction area, will be implemented.
During project operations, discharges of water used for power generation may influence water quality in Seminoe Reservoir, the downstream Kortes Reservoir, and the segment of the North Platte River below Kortes Dam known as the “Miracle Mile”, primarily with respect to temperature. This segment of the North Platte River is designated as an Outstanding Resource Water where the existing quality is maintained and protected. Accordingly, this certification requires that the provisions of Chapter 1, Section 13 (a)(ii) and (iii)(A) and (F) of the Wyoming Water Quality Rules be met.
To support compliance with Chapter 1 of the Wyoming Water Quality Rules, a 10,000 ft2 x 3-ft rockfill blanket will be installed at the inlet-outlet location to minimize scouring and sediment resuspension during project operations. In addition, real-time monitoring and an adaptive management plan (AMP) that includes threshold-activated operational curtailments will be implemented.
The draft certification, the draft December 19, 2025 AMP, and the certification request that includes associated technical and modeling reports are available at the January 3, 2025 Public Notice website at https://deq.wyoming.gov/water-quality/wqd-public-notices/.
Questions about the proposed water quality certification should be directed to Eric Hargett by email ([email protected]) or phone (307-777-7079). Written comments must be addressed to Eric Hargett, Wyoming DEQ/WQD, 200 W. 17th Street – 4th floor, Cheyenne, WY, 82002, and be postmarked on or before 5:00 p.m. on February 2, 2026 to be considered. Electronic comments may only be submitted through and accepted by the Wyoming DEQ comment portal provided at https://wq.wyomingdeq.commentinput.com/. Phone and email comments will not be accepted.
The WDEQ will host a public meeting from 5:30 PM to 8:30 PM local time, on January 21, 2026, at the Gateway Center Room (GW225), Casper College, 125 College Drive, Casper, Wyoming. The purpose of the meeting is to provide an additional comment opportunity for the proposed water quality certification. The scope of the meeting will be limited to information regarding the proposed water quality certification. At the meeting, the WDEQ will present findings on the Seminoe Pumped Storage project’s potential influences on water quality before accepting public comments. Written comments can also be provided to the WDEQ at the meeting.
Para español, visite deq.wyoming.gov. Americans with Disabilities Act: special assistance or alternative formats will be made available upon request for individuals with disabilities. Please provide at least fourteen (14) days before the close of the public comment period for such requests.
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