3.2 Environmental Factors

configuration must be able to economically design and construct the dam to provide enough water volume to support approximately 10 hours of storage at the desired capacity for generation and pumping.

Access to Seminoe Reservoir provides a lower reservoir of significant volume such that upper reservoir operation is unlikely to cause disruption to Reclamation operations. In previously considered configurations in the 2011 Preliminary Permit Application, the 2013 Reclamation Phase I report, and the 2014 Successive Preliminary Permit Application, utilizing Kortes Reservoir was an option; however, due to its relatively small storage volume (4,765 ac-ft, substantially less than the selected alternative’s storage volume [13,427 ac-ft]) against Seminoe Reservoir’s storage volume (>1,000,000 ac-ft), Kortes Reservoir was ruled out due to the fluctuations in elevation and downstream impacts that a pumped storage facility could impose. The 2013 Reclamation Phase I report acknowledged the challenges of utilizing Kortes Reservoir as the lower reservoir for pumpgeneration, and the necessity of stream augmentation was included in alternatives that utilized Kortes as the lower reservoir to meet downstream flow requirements. Reclamation’s Phase II report stated that long-term operational impacts to Seminoe Reservoir would be minimal, that the pumped storage facility would not change the timing or frequency of releases, and, therefore, would not affect overall water supply or downstream flows. The feasibility study found that the proposed volume of water pumped into the new reservoir would be very small relative to the volume of water in the existing Seminoe Reservoir and would, therefore, be unlikely to change reservoir elevations such that there would be adverse effects to Seminoe Reservoir resources (Reclamation 2013b).

Additional favorable factors present in the region adjacent to Seminoe Reservoir, northeast of Rawlins and south of Casper include:

• Rawlins is the largest town in Carbon County, affording nearby services to support

Project development, construction, and operation. • Casper is one of the largest cities in Wyoming, affording substantial services to support

Project development, construction, and operation. • Good aggregate material on the Project site that will be excavated can likely be utilized in the construction of the RCC upper reservoir dam. • Good highway access is available to the Project site, including Interstate 80 and

Interstate 25.

Environmental screening factors are key to site selection. These include biological and cultural factors, along with general land use policy.

Figure 3.2-1 shows the location of the proposed Project configuration overlaid with the location of the Bennett Mountains WSA. The Bennett Mountains WSA does not currently have a wilderness designation.