Friday, DECEMBER 5, 2025 |
Photo – Seminoe Dam – Bigfoot99 file photo
Natrona County Commissioners sent a formal letter this week to the Federal Energy Regulatory Commission expressing concerns about a hydro power pumped storage project planned at Seminoe Reservoir in Carbon County.
The proposed 900-megawatt hydro energy storage project would require the construction of a new reservoir 1,000 feet above the existing Reservoir near a prime fishing area along the North Platte River. The complex mechanical system would transport water between the upper reservoir and Seminoe Reservoir to store energy and generate power, according to the Utah-based company behind the project–rPlus Hydro.
In a letter to the Federal Energy Regulatory Commission, Natrona County commissioners expressed support for Wyoming Game and Fish’s recommendations that the project cease operations during critical times for wildlife.
According to the letter sent to FERCA from the Natrona County Commissioners, “This project will have a substantial impact on the health, safety, welfare, custom, culture and socio-economic viability of not just Carbon County but also Natrona County.”
The project is in the development stage and must seek approval from the Federal Energy Regulatory Commission before final approval at the local level.
According to rPlus Hydro’s website, the company uses the same language deployed by wind development companies over the last decade and more. The company touts the project’s ability to “bring substantial economic benefits to the local community and will serve as an important element of Wyoming’s modernized and reliable energy infrastructure.”
The project calls for seven specific work areas, one new reservoir located about 10,000 feet east of the Seminoe Dam, along with underground tunnels, a powerhouse, and an intake-outlet in the existing reservoir. The project also calls for relocating an existing transmission line as well as building a new line.
A powerhouse to drive the system would be built halfway between the existing reservoir and the new upper body of water. The powerhouse includes a main intake valve, a pump turbine, a motor generator and a powerhouse crane. According to the company’s depiction shown on rPLus Hydro’s website, the underground facility stands four stories tall.
The initial fill requirement of the upper reservoir is about 10,000 acre-feet of water. The use of that much water has brought scrutiny from Wyoming Game and Fish Department about possible impacts on the fisheries in and around the Seminoe Reservoir.
A Final Environmental Impact Statement (FEIS) is expected in 2026.
