Constructed by the Sacramento Municipal Utility District in the early 1970s, the Rancho Seco Nuclear Generating Station was a 2,772 MWt Babcock & Wilcox pressurized water reactor located 25 miles south-east of downtown Sacramento. The reactor entered commercial operation on April 17, 1975 and operated until June 1989. The facility filled only 40% of its lifetime capacity factor, having been closed by public vote in June 1989, primarily for economic reasons. Ratepayers had seen rates double in the last four years of operation to pay for improvements to the plant while electricity generated by natural gas was priced at half that of the electricity generated by Rancho Seco.