March 11th 2026 |
Photo – Courtesy of WY DEQ
The Wyoming Department of Environmental Quality has signed off on the Seminoe Pumped Storage Project.
Utah‑based rPlus Hydro, also known as Black Canyon Hydro, has proposed building a pumped storage facility at Seminoe Reservoir. Plans call for a 13,000‑acre‑foot man‑made lake to be built on a mountaintop above Seminoe. The two reservoirs would by an underground electrical powerhouse. During periods of high wind‑energy production, water would be pumped from the reservoir into the upper lake, where it would be stored until needed. When demand outpaces production, the water would flow downhill through the underground turbine, generating approximately 900 megawatts of electricity for up to 12 hours. The cycle would repeat needed.
Wildlife conservationists have raised concerns about the project, including its potential impact on the blue‑ribbon Miracle Mile fishing area and the Seminoe-Ferris bighorn sheep herd.
The Wyoming Department of Environmental Quality has issued a Clean Water Act Section 401 Water Quality Certification for the project.
The state DEQ certification is an important permitting milestone for the controversial project.
Section 401 of the Clean Water Act gives states authority to certify that discharges proposed under federal permits or licenses will protect state water quality. The issuance of the Section 401 certification for the Seminoe Pumped Storage Project fulfills rPlus Hydro’s obligation to show that it will protect the North Platte River.
In a media release about the certification, Wyoming DEQ stated that when the Seminoe Pumped Storage Facility is operating, discharged water used for power generation may briefly change temperatures in Seminoe Reservoir, Kortes Reservoir, and the Miracle Mile, located roughly two miles from the proposed construction site. Because the Miracle Mile is designated as an Outstanding Water Resource under Wyoming Surface Water Quality Standards, the project is prohibited from negatively altering water quality in the area.
Wyoming DEQ wrote that a 115-page adaptive management plan, including monitoring, threshold‑triggered operational limits, feedback loops, and reporting, was developed to ensure compliance with state standards.
Submitting public comments on the massive project were 65 organizations individuals, including the Board of Carbon County. Private individuals also submitted public comments during Wyoming DEQ’s 30‑day review period. Most comments focused the project’s impact on water quality.
In its 178-page response, DEQ wrote that since the Miracle Mile is designated as an Outstanding Water Resource, its water quality and uses must be maintained at the level that existed at the time of its 1979 designation.
The state agency recommended real-time monitoring of water temperature, dissolved oxygen, and turbidity to ensure the project does not exceed allowable thresholds.
The water‑quality certification is one of several permits and licenses rPlus Hydro must obtain before construction can begin.
While Wyoming DEQ conducted extensive water‑quality modeling and analysis, the agency did not address the project’s potential effects on the surrounding land, including bighorn sheep herds. The company must still secure authorization from the U.S. Army Corps of Engineers, the Bureau of Reclamation, and the Bureau of Land Management, which is being asked to amend the Rawlins Resource Management Plan to allow year‑round construction. Under the current plan, work is limited to a four‑month window from May through August to avoid disturbing the bighorn sheep herds.
If the project is granted approval by the permitting agencies, the Federal Energy Regulatory Commission, or FERC, has the final say on whether the Seminoe Pumped Storage Project will move forward or not. FERC is expected to issue a Final Environmental Impact Statement later this year. Once that document is complete, the five‑member FERC commission in Washington, D.C., will vote on an Order Issuing License.
If approved, the project would receive federal authorization to begin construction. Opponents may still file a Request for Rehearing or challenge the decision in the U.S. Court of Appeals, the only body that can overturn FERC’s final determination.
While many hurdles remain, Wyoming DEQ’s issuance of a Section 401 Water Quality Certification brings the Seminoe Pumped Storage Project one step closer to reality.
