Eyebrows were raised last week when the Idaho Statesman’s Rocky Barker reported some of the details of a huge proposed “pumped storage” electricity generation project that would include a large dam and reservoir above the existing Anderson Ranch Dam Reservoir on the South Fork of the Boise River, as well as accompanying wind and solar farms – all of which have understandably caught the interest of anyone interested in energy and wildlife issues in southwest Idaho and beyond.

Proposed and pending before the Elmore County (Mountain Home) Planning and Zoning Commission are multiple applications by Cat Creek Energy, which envision a massive energy project that would include:

  • A new hydropower reservoir above Anderson Ranch Dam Reservoir, which during certain times would receive water from the existing reservoir through large pumps and then release that water back downstream during times of heavy electricity use to generate additional power through Anderson’s existing generation units;
  • A 40 megawatt (MW) solar farm consisting of about 171,000 solar panels.
  • A 110 MW wind farm consisting of about 39 large wind turbines.
  • A 3.4-mile earthen dam to impound a 50,000 acre-foot upper reservoir above Anderson Ranch.

Timing and other details for the project won’t become more clear until the applications move further through the Elmore County P&Z and other regulatory processes, which are certain to be considerable for environmental reviews alone. According to Cat Creek Energy, this project would connect to existing major transmission lines in the Mountain Home area and allow for better energy flows in multiple directions throughout the region. The project would have a 550 megawatt “nameplate” or maximum generating capacity, which is about the equivalent of a medium-sized coal-fired power plant yet far larger than Idaho Power’s most recent big generation acquisition, the 300MW Langley Gulch natural gas generating station near New Plymouth, west of Boise.

As Barker’s Statesman story points out, many questions remain to be answered regarding the project and its potential environmental and other impacts. Further, no utility has been identified as the purchaser of the new hydropower plant’s output.