The U.S. Department of the Interior and the Central Utah Water Conservancy District, as joint leads, have evaluated the impacts of a proposed replacement of the Olmsted Hydroelectric Power Plant and have issued a Final Environmental Assessment and Finding of No Significant Impact for this project, Interior said in a notice to be published in the March 9 Federal Register.
The long-existing facility is located at the mouth of Provo Canyon in Utah. Water for this hydroelectric plant is diverted from the Provo River approximately 4.5 miles up the canyon. It is conveyed through the Olmsted Flowline located along the foothills of Mount Timpanogos above the Provo River. The plant was able to produce about 10 MW when operating at capacity. In 1912, Utah Power & Light (now PacifiCorp) purchased the Olmsted Power Plant through the acquisition of Telluride Power Co.
As part of a plan to meet the projected water demand for Wasatch Front communities, the federal government, acting through the U.S. Bureau of Reclamation, acquired the plant in 1987. The acquisitions included the Olmsted diversion structure on the Provo River, Olmsted Flowline, penstocks, pressure box, powerhouse, and associated rights-of-way. The acquisitions also included water rights to provide water for the Bonneville Unit of the Central Utah Project through a series of administrative exchanges involving Strawberry Reservoir, Utah Lake, and Jordanelle Reservoir. A settlement was reached in 1990 among the District, Department of the Interior and PacifiCorp that outlined compensation and provided for interim operation of the Olmsted plant. Beginning Sept. 21, 2015, when the term of the settlement runs its course, the District, by way of Interior, will assume the entire operation and maintenance of the Olmsted plant. It is anticipated that PacifiCorp will operate a substation associated with the plant through a new deal with Interior.
The proposed action under the environmental review would include:
- Constructing a new powerhouse as a replacement of the existing powerhouse, including a smaller power generation unit for flows that are less than powerhouse minimum flow limitations
- Replacing the four existing penstocks with a single buried penstock
- Utilizing the hydraulic head of the 10 million gallon (MG) Olmsted Flow Equalization Reservoir (10 MG Reservoir)
- Constructing a power transmission line to connect the proposed powerhouse to either the Olmsted or the Hale substation
The plant houses four generating units. One has been decommissioned and is used for spare parts, two are original, and the last was rebuilt in 1980. The two original units operate at 50% efficiency. The 1980 model operates at 70% efficiency. New generating units are anticipated to operate at over 90% efficiency.
The plan includes construction of a new replacement powerhouse, north of the existing powerhouse. The proposed powerhouse could include multiple generating units with an estimated capacity of 11 MW. The Western Area Power Administration would be responsible for the marketing of power. Transmission of power would be done by agreement among Western and PacifiCorp.