Several US nuclear power plants closed well before their design lifetimes, including Rancho Seco in 1989 in California, San Onofre Unit 1 in 1992 in California (units 2 and 3 are still operating), Zion Nuclear Power Station in 1998 in Illinois and Trojan Nuclear Power Plant in 1992 in Oregon. Humboldt Bay Nuclear Power Plant in California closed in 1976, 13 years after geologists discovered it was built on a fault (the Little Salmon Fault). Shoreham Nuclear Power Plant never operated commercially as an authorized Emergency Evacuation Plan could not be agreed on due to the political climate after the Three Mile Island and Chernobyl accidents.