2.1.3 2013 Phase II Pumped Storage Evaluation Study

After evaluating various alternatives at the Kortes and Seminoe Reservoirs and selecting configurations for further consideration, Reclamation drafted a follow-up (Phase II) study to further determine the technical, environmental, and economic feasibility of pumped storage at Seminoe Reservoir (Reclamation 2013b). Alternatives 5A1 and 5D1 from the Phase I Study were not examined further in the Phase II Study due to connection to Kortes Reservoir being infeasible due to its relatively small storage volume in comparison to Seminoe Reservoir’s storage volume, where pumped storage operations appeared likely to interrupt Kortes Reservoir operations. The site of 5A1 was taken and used for a new alternative developed in the Phase II Study called 5A3, which connects to Seminoe Reservoir instead of Kortes Reservoir.

The Phase II Study provides a refined preliminary design and operations, economic, and environmental analyses at the selected pumped storage sites, including evaluations of geology and seismicity, single speed vs. variable-speed technology, transmission considerations, cost opinion and project schedules, operational analyses, economics, and environmental effects analysis. No fatal flaws related to the geology and seismology for the Seminoe sites were identified during the Phase II Study.

Environmental impacts from the Phase I Report were further explored in the Phase II Study, including impacts to fisheries, vegetation and wildlife, surface water supply and quality, cultural and Native American resources, recreation, land use, site access, and air quality.

Seminoe Reservoir supports several game fish species such as Brown Trout, Rainbow Trout, Cutthroat Trout, and Walleye as well as many non-game fish species including Carp, Lake Chub, Emerald Shiner, White Sucker, Longnose Sucker, and Fathead Minnow. Downstream fisheries in the North Platte River include several game and non-game fish species as well. Temporary construction-related impacts to fish populations could include increased turbidity from in-water work for tunneling and intake structure installation. Construction may result in temporary and permanent loss of fish habitat along Seminoe Reservoir shoreline. Long-term impacts to fish from entrainment at the new intake structure would be mitigated by incorporation of a fish screen in the intake design. Long-term, the operations of a new upper reservoir were not anticipated to have impacts to Seminoe Reservoir elevation, storage volume, water temperature, or to fisheries downstream of Seminoe Reservoir.

Vegetation surrounding Seminoe Reservoir consists of sand dunes, yucca, greasewood, sagebrush, salt sage, willows, marsh grasses, pine trees, and juniper trees, among other vegetation species. Wildlife present includes mule deer, pronghorn, coyotes, and migratory birds, among other species. Special-status wildlife species identified in 2013 as potentially affected by the alternatives under study include the Greater Sage-grouse, least tern, piping plover, whooping crane, Pallid Sturgeon, blowout penstemon, Ute ladies’tresses, western prairie fringed orchid, and the black-footed ferret. Temporary construction-related impacts on vegetation and wildlife would include removal of vegetation for construction and staging along with dust, noise, and vibration impacts. Use

of equipment and vehicles would have the potential to physically damage wildlife and their habitat, which could include impacts to special-status species and their habitat. There would be a permanent loss of vegetation and wildlife habitat with the construction of the access road, dam, pump-generating facilities, and inundation of the upper reservoir area.

The footprint of Alternative 5C is in the Morgan Creek Wildlife Habitat Management Area, and the footprints of Alternatives 5A2 and 5A3 are located in the Bennett Mountains WSA. The proposed alternatives all occur within “Core Population Areas” for the Greater Sagegrouse. Consultation with the Wyoming Game and Fish Department would be required as well as the implementation of measures to prevent impacts that would adversely affect Greater Sage-grouse populations and their habitat.

Surface water resource impacts to Seminoe Reservoir are expected to be minimal from long-term operations of the upper reservoir. The Project would not alter the flow releases of Seminoe Reservoir and, thus, would not affect water supply or downstream flow requirements. Downstream of the Kortes and Seminoe Reservoir, the Miracle Mile is classified as a Class 1 water body by the State of Wyoming; Class 1 water bodies do not allow new point source discharge and require carefully regulated nonpoint source discharges. Temporary water quality impacts could include increases in turbidity from inwater work and stormwater runoff from construction and staging areas. Use of construction equipment in and near the reservoir could introduce other contaminants into the water. Permanent water quality impacts could include slight changes in temperature as water is pumped between the upper reservoir and Seminoe Reservoir.

The Phase II Report indicated a high likelihood of encountering cultural resources around Seminoe Reservoir as humans have inhabited the area for over 12,000 years. Cultural resources in the area may include archeological sites, historic sites and properties, and properties important to Native American cultures. Construction activities including excavation have the potential to damage or unearth cultural and archaeological resources. Creation of the new reservoir may permanently inundate known or previously unknown cultural or archaeological sites.

The Phase II Study concluded that the alternatives examined were not recommended to move forward for additional study at the time due to market conditions such as estimated net present benefits and existing renewable generation not being favorable for large, pumped storage facilities. The study recommended that further evaluation of pumped storage facilities focus on areas with high transmission capabilities and high potential for renewable resources, particularly wind power.

A summary of site characteristics for the Seminoe site options that were evaluated in the Phase II Study is provided in Table 2.1-3. A map of site configurations is provided in Figure 2.1-4.