Wyoming Hydroelectric Storage Project Faces Opposition Over River, Wildlife Impacts
A $4 Billion Project at Seminoe Reservoir Draws Scrutiny From Anglers, Officials, and Wildlife Biologists
A proposed pumped-water energy storage facility on Wyoming’s Seminoe Reservoir is facing significant pushback from anglers, local business owners, elected officials, and wildlife biologists, who say the $4 billion project threatens the North Platte River’s celebrated Miracle Mile trout fishery and a bighorn sheep herd that plays a critical role in sustaining the species across the region.
Opponents testified before the Legislature’s Travel, Recreation, Wildlife and Cultural Resources Committee, raising concerns about what they described as an inadequate federal permitting review and flawed assumptions submitted by project developer rPlus Hydro.
What the Project Would Do
Pumped-water storage works by moving water uphill into an elevated reservoir during off-peak electricity demand hours — typically when wind and solar generation is abundant and wholesale power prices are low. That water is then released back through hydroelectric turbines during evening high-demand periods, functioning, as the company describes it, as a large-scale “water battery.”
rPlus Hydro proposes constructing a 13,400-acre-foot reservoir in the Bennett Mountains above Seminoe Reservoir, near the existing dam on the North Platte River. Kevin Baker, the company’s deputy general counsel, told the legislative committee the facility would enhance grid reliability and reduce costs for ratepayers. He cited a Federal Energy Regulatory Commission analysis suggesting the project could yield $200 million in annual savings.
“It’s an enormously large project to meet Wyoming’s future energy needs,” Baker said, adding that pumped storage is among the most cost-efficient long-duration energy storage options currently available.
Critics Challenge Key Claims
Opponents disputed multiple assertions from the company. Several witnesses contended that the project would result in a net energy loss rather than a net gain, undermining its core justification. Others raised concerns about water temperature increases that could harm trout populations in the Miracle Mile stretch of the North Platte, a fishery prized by anglers and relied upon by businesses throughout the region.
Critics argued that rPlus Hydro’s temperature analysis draws on only five years of data from the 2010s, a period that predates more recent drought conditions and does not reflect elevated stream temperatures now linked to declining water levels. Seminoe Reservoir is currently at just 32% of its total storage capacity.
State Sen. Larry Hicks, a Republican from Baggs, referenced the ongoing water crisis affecting the Colorado River system and Flaming Gorge Reservoir as context for his skepticism. “The way I understand the analysis is that there’s going to be many more low water years,” he said. Hicks also challenged the project’s economic rationale, noting that Wyoming is a net electrical exporter and that rPlus Hydro is relying on federal tax credits to help finance construction.
Casper Mayor Ray Pacheco urged the committee to take the concerns seriously. “These concerns are not theoretical for us,” he said. “Casper relies directly on the North Platte River for drinking water, wastewater treatment, recreation, tourism and the quality of life.”
Wildlife at Risk
The Wyoming Game and Fish Department raised concerns about the project’s five-year construction phase, warning that blasting and heavy industrial traffic could severely harm the Ferris-Seminoe bighorn sheep herd — a population that wildlife managers use to bolster bighorn numbers elsewhere in the state. A department official told the committee those impacts “may be unresolvable,” though the agency retains the ability to formally object to the project.
Local businesses that depend on the North Platte fishery also voiced alarm. CiCi Oliver, who operates the Ugly Bug Fly Shop in Casper — which employs 45 people — said the project’s most troubling aspect is the regulatory precedent it could set. “This proposal requires exemptions from existing land use and wildlife protections in order to move forward,” she said, suggesting that a project requiring such carve-outs may not be suited to the proposed site.
Trout Unlimited joined local business owners and elected officials in questioning whether the Federal Energy Regulatory Commission’s review has adequately tested the developer’s claims or given sufficient weight to local concerns. For their part, wildlife groups in Wyoming have pursued legal challenges on related environmental issues — including, separately, federal protections for native species facing habitat pressures across the West.
What Comes Next
The legislative committee hearing was an informational session, not a vote. The Federal Energy Regulatory Commission remains the primary regulatory body overseeing the permitting process. Wyoming Game and Fish still has an opportunity to lodge a formal objection. The project’s timeline and ultimate approval will depend on FERC’s final environmental determinations and any conditions it places on the developer before construction could begin.