LIHI Certificate #62 - Cutler Hydroelectric Project, Utah
March 25, 2020 -COVID-19 Update: Pacificorp has issued this press release announcing closures of most of their recreation areas. Information on the status of their recreation facilities are available at https://www.pacificorp.com/community/recreation.html
The Bear River Basin is located in northeastern Utah, southeastern Idaho, and southwestern Wyoming. It comprises approximately 7,500 square miles of mountain and valley lands (2,700 in Idaho, 3,300 in Utah, and 1,500 in Wyoming). The Bear River begins in the Uinta Mountains in Utah and extends 500 miles, crossing state boundaries five times before ending in the Great Salt Lake. It is the largest tributary to the Great Salt Lake and the largest stream in the western hemisphere that does not empty into an ocean. The Bear River ranges in elevation from over 13,000 to 4,211 feet and is unique in that it is entirely enclosed by mountains, thus forming a huge basin with no external drainage outlets.
Developed and undeveloped agricultural lands throughout the basin, as well as urban areas, are concentrated in valleys along the main stem of the river and its tributaries. The Bear River watershed also includes vast amounts of federal lands (Bureau of Land Management and Forest Service), private lands, and state lands that serve a range of natural and agricultural functions. The Bear River is a highly regulated system. The major headwater storage facility is Bear Lake, the discharges from which are primarily for irrigation and flood control.
This application for Low Impact Hydropower Certification pertains to the Cutler project on the Bear River. PacifiCorp operates five hydroelectric developments in the Bear River Basin. Three of the upstream developments—Soda, Grace, and Oneida—are operated under the FERC license for the Bear River Hydroelectric project No. 20 in Idaho. The Last Chance development, also located upstream in Idaho, was granted an exemption from FERC licensing in 1981 due to the project’s small size. The Cutler hydroelectric project is operated under FERC license No. 2420 in Utah. A sixth facility on the Bear River, the Cove development, was decommissioned in 2006. The Cutler project is located 44 miles downstream of the Oneida development in Utah, near the confluence of several major tributaries. Figure 2.1-1 provides a map of the project locations.
The Cutler project includes a 545-foot-long, 109-foot-high concrete gravity arch dam built in 1927. The dam has a spillway containing four 30-foot-wide by 14-foot-high radial gates. A 7- foot-diameter low-level sluiceway is located near the base of the dam and controlled by a slide gate. Irrigation canal intake gates are located at each abutment of the dam and are an integral part of the structure. The project is operated seasonally and at full pool (4407.75 feet msl) the reservoir active storage capacity fluctuates from approximately 5,800 acre feet from March 1 through December 1 to about 7,800 acre feet from December 2 through February 28. Much of the reservoir has the characteristics of a shallow-water emergent marsh; the southern portion of the reservoir has a mean depth of 1.8 feet, while the deeper section of the reservoir to the north has a mean depth of 3.6 feet. The flowline intake is a concrete tower located in the reservoir approximately 60 feet upstream of the dam. It connects to an 18-foot-diameter steel-lined conduit that passes through the dam (Figure 2.2-2). A 1,160 foot-long, 18-foot-diameter steel penstock carriers water to an 81-foot-high, 45-foot-diameter steel surge tank. Two 112-foot-long steel penstocks bifurcate from the surge tank and lead to the powerhouse. The powerhouse is a 60-foot by 123-foot brick building containing appurtenant facilities and two vertical Francis generating units with a total installed capacity of 30 MW. The Cutler project has an average annual generation of 84,185 MWh.
The Cutler hydroelectric project operates seasonally in normal and low-water years, generally from fall through early summer, based on the availability of flows after irrigation commitments are met (during high-water years there may be additional available flow). During the normal operation period, the facility is operated as a daily peaking project. When inflows to the reservoir are too low to keep an efficient load level on the generating units, water is stored on a daily basis until it reaches a level appropriate for power generation, then the water is released. Typically, the project suspends normal operation during low summer flows (July through September), but the facility remains available to provide short-duration emergency generation (spinning reserve). During normal operation periods, the project is operated in a semi-automatic mode whereby the generators are started and synchronized to the system manually by the local operator. Once on- line, the units are controlled remotely by the System Dispatcher to control the load on the generators to meet system requirements and to stay within the reservoir elevation guidelines. Substations containing step-up transformers and circuit breakers are located adjacent to the Cutler powerhouse. The substation serves as the point of interconnection to the transmission grid system.
|LIHI Certificate No.||62|
|LIHI Certificate Term||December 31, 2014 - December 31, 2022|
|Location||Located at river mile 65.9 on the Bear River, 44 miles downstream of the Oneida development in Utah, near the confluence of several major tributaries.|
|Installed Capacity||30 MW|
|Average Annual Generation||84,185 MWh|
|Facility Type||Daily peaking|
|FERC No.||P-2420 issued 1994, expires 2024|
August 12, 2015: LIHI Executive Director Michael J. Sale, using authority delegated from the LIHI Governing Board, has determined that the Cutler Hydroelectric Project (FERC No. 2420) continues to meet the LIHI Certification Criteria. The effective certification date for the Cutler Project is December 31, 2014 for an eight (8) year term, which will expire on December 31, 2022, with the following conditions:
- Condition 1. The facility owner shall notify the Utah Division of Wildlife Resources, Northern Region Aquatic Manager, prior to any reservoir drawdowns that exceed normal Cutler operating conditions, and work with that agency to minimize the impact of any such drawdown to sensitive aquatic species.
- Condition 2. If a viable population of bluehead sucker (Catostomus discobolus) is found in or below Cutler Reservoir in the future, a meeting between PacifiCorp and the UDWR will be initiated to discuss life history needs of this species. The facility owner shall notify LIHI within 30 days of any such finding and shall keep LIHI informed of the results and courses of action taken as a result of the discussions with UDWR.
February 3, 2015: The Low Impact Hydropower Institute received a complete and timely application for a new term of Low Impact Certification for the Cutler Hydroelectric project on November 20, 2014. Please see the application files below.
October 22, 2010: The Cutler Hydroelectric Project has been certified as low impact for a five year term, effective December 31, 2009 and expiring December 31, 2014.
December 31, 2009: PacifiCorp Energy has submitted an application for the certification of the Cutler Hydroelectric Project. Public comment period will remain open for 60 days.