June 1996 Blazer

Power development on the bear river

THE HISTORY BLAZER ATEClrS OF UTAH'S PAST FROrM THE Utah State Historical Society 300 Rio Grande Salt Lake C i t U~ T 88101 ( 801) 533- 3500 FAX ( 801) 333- 3303 Power Development on the Bear River ONEO F UTAH'SE ARLY HYDROELECTRIC DEVELOPERS was L. L. Nunn who specialized in high- head technology- generating electrical power from small, swift, mountain streams. In 1902 he Ned for water rights on northern Utah's Bear River, recognizing its potential for power-generation. Meanwhile, in 1902 Utah Sugar Company built its own plant on the Bear to power its Garland factory. This did not discourage NUM, however, as the river was 350 miles long and offered other sites. He envisioned natural Bear Lake doubling as an imgation reservoir and as one part of a hydroelectric system. In 1907 Nunn received permission from the U. S. Department of the Interior to develop Bear Lake for this purpose, but for some reason he did not proceed. Perhaps he was too involved with building his 11,000- kilowatt hydroelectric plant at Grace, Idaho. Utah Power and Light Company, formed in 1912, soon bought out Grace and Nunn's other Telluride Power Company developments in northern Utah. UP& L also had a vision for developing Bear Lake, but it included the entire Bear River drainage area and would require superior capital and technical staff. Its holding company, Electric Bond and Share ( EBASCO), owned hundreds of small utility companies across the country, had its own engineering department and construction company, and was experienced in low- head hydroelectric development. Backed by EBASCO capital and expertise, UP& L built five power and pumping stations over the next 15 years and upgraded existing facilities. Most were in the Bear River zone. By 1922 more than half of UP& L's total 224,000 kilowatt output originated from this system. The Cutler Power Plant, built in 1927 as the last venture in the area and the most expensive, would increase this output by 30,000 kilowatts. The Cutler station is located in Bear River Canyon halfway between Logan and Tremontm. Its purpose was not just to capture the Cache Valley runoff lost each spring because Utah Sugar's Wheelon plant was too small. The Cutler facility would also work with the Snake River system to create a massive interconnecting complex serving Idaho, southwestern Wyoming, and northern Utah. Cutler was and is the largest low- head hydroelectric plant in Utah. It stands today virtually as it was built 70 years ago. It uses the same generation process as a smaller plant, or four main systems: water regulation, conduit, power generation, and electrical. But in a plant this size almost every component is larger, more powerful, and more complicated than in a high- head plant. For instance, water regulation features at the Cutler plant include the dam ( 570 feet long, 125 feet high, and 50 feet thick) complete with spillway, intake tower with 18- foot diameter water passage winding inside it, intake screens, steel flowline to a surge tank, sluiceway at the bottom of ( more) the dam; various gates and valves that control all of the above; hoists, motors and compressors to control the gates and valves; and electrical control lines which send signals to open and close gates and valves at the dam and along the pipelines. The sheer size of Cutler's structures demanded careful engineering. The intake tower is 108 feet high. Its concrete base alone is 76 feet high and 48 feet in diameter. Atop the base 17- foot screens collect water. Inside the tower is the 18- foot diameter water passage. This channel winds through the tower and meets a steel flowline near the sluiceway. To control the flow of water through this channel and flowline, a cylinder guides an 18.5- foot round intake gate which when closed plugs the water passage. Atop the screens are 15- foot steel platform supports. The platfonn holds a motor and giant stem hoist that raise and lower the tainter ( intake) gates. Also on the platform is a gantry crane that runs along a circular track raising and lowering the huge intake screens. Even the surge tank is massive: 81 feet tall and 45 feet in diameter. It is the backup in regulating water supply to the turbine- generators in the powerhouse. Sometimes engineering glitches in such a massive industrial facility are surprisingly minor. The dam, besides harnessing stream flow for power generation, doubles as an irrigation catchment. At both sides of the dam base are intakes to irrigation canals. Air compressors had to be installed ( plus a concrete housing) that create bubbles to keep ice from forming around the intake to the north irrigation can&- a small but crucial modification. The powerhouse is the heart of the plant. On its first floor are iffoot buttemy valves that regulate water from the penstocks ( Cutler has two of these main water channels) to the generators. There are also oil tanks and pumps for the hydraulic governors, a battery room, a fire pump, a rheostat room to regulate the generators' voltage, and a room for the cables leading to the transformers. The second floor of the powerhouse contains the turbine- generators themselves: two 15,000- kilowatt General Electric units attached to Francis reaction turbines by vertical shafts. The old DC exciters ( small generators that provide field current for the large motors) still function on one of the units. Below the powerhouse is the electrical switchyard. It has a steel lattice switchrack, bus bars, switches, and transformers. Its size has been increased by one- third since 1927 and some older transformers have been replaced, but otherwise the switchyard too remains as it was in 1927. Like Nunn's high- head hydroelectric plant near Beaver in central Utah, UP& L's Cutler Plant has been listed in the National Register of Historic Places. This is appropriate, for it stands as Utah' s only example of the large- scale, low- had , sophisticated hydroelectric plants built throughout the West in the 1920s. Source: Cutler Hydroelectric Power Plant Nomination Form, National Register of Historic Places, Presewation Office files, Utah Division of State History. RIE HISTORYBL AZERi s produced by the Utah State Historical Society and funded in part by a grant fiom the Utah Statehood C e n W Commission. For more information about the Historical Society telephone [phone].