Powerhouse

Powerhouse. . Hydroelectric power is produced through generating units in the Powerhouse. The generators produce electricity at 13,800 volts which is stepped up to 115,000 and 230,000 volts for transmission. The rotors on units 1, 2, and 3 are 35 feet in diameter and weigh 517.5 tons. During generator operation, the outside edge of the rotor travels at a speed of about 113 miles per hour.

Generator No. 1 went into hydroelectric power production Saturday, January 21, 1956 when Governor Norman Brunsdale pushed the starting button. Generator No. 2 went into production in February and No. 3 later that year. At that time, generators No. 4 and No. 5 were not complete, but room was left in the powerhouse for their construction.

On an average year the generating units have a combined annual output of 2,600,000 megawatt hours of electricity. Electrical power is transmitted from the project through seven transmission lines to various substations and is marketed by Western Area Power Administration at the Watertown Dispatch Center in South Dakota.

The five pair of cylindrical surge tanks act as a shock absorber for water flowing through the penstocks. The water level in each surge tank is approximately the same elevation as the lake. Each tank is 136 feet tall, 65 feet in diameter and has a capacity of 3.4 million gallons of water.