Hydropower Projects

The City of Idaho Falls has operated a municipal electric generation system since 1900, when a small generator was installed in an irrigation canal to create electricity for street lights. Today the City owns and operates five hydropower plants along the Snake River, providing on average about one-third if the electricity used in the City. Most of the balance is purchased from the Bonneville Power Administration, a federal agency that markets electricity generated at 31 hydro facilities along the Columbia and Snake rivers, along with one nuclear plant.

Current System

The City's hydropower system is composed of two main projects - the Bulb Turbine Project and the Gem State Project. The Bulb Turbine project replaced or augmented three hydroelectric facilities constructed along the Snake River between 1912 and 1940. The plants at the original Upper and City sites were destroyed by the Teton Dam collapse and flood in 1976 and required replacement. The Old Lower Plant facility did not sustain as much damage and was retained. The new bulb turbine facility was constructed adjacent to it.

Bulb Turbine Project

Construction of these three plants - the Upper, City and Lower plants - began in 1978 and was completed in 1982. The Bulb Turbine Project was one of the first in the United States to use the European technology of placing the turbine-generator entirely within a horizontal water passage. The generator is enclosed in a water-tight seal or "bulb" and connected to a downstream runner by a horizontal shaft. The advantage of using this technology over the more common vertical-shaft turbines, is that it better utilizes the relatively low-head (water height) in the stretch of the river around Idaho Falls.
The available head at each of the three sites is approximately 19 feet, which is low compared to most utility-scale hydroelectric projects. Each of the three plants channels up to 6,000 cubic feet per second of water through the turbines to produce up to 8 megawatts of energy each. The total production from the three plants sites produces approximately 100 million kilowatt-hours of electricity annually.

Gem State

The Gem State Plant is nearly as large as the Bulb Turbine Plants combined. It was constructed at an abandoned hydroelectric site about five miles south of the City. Construction began in 1985 and the plant was completed in 1988.
The powerhouse contains one vertical Kaplan Turbine with an installed capacity of 22.6 megawatts operating under a 43 foot head. Its 40 foot high, 3600 foot long earth-fill dam, impounds a reservoir of 5,000 acre-feet with a surface area of 305 acres. Gem Lake, as it's known, has become a popular area for fishing and boating for area residents. The plant produces approximately 120 million kilowatt-hours of electricity annually.

Additional Information

For more information about hydropower, visit the Foundation for Water and Energy Education's website.