The company said Thursday morning it would close the Clinton Power Station in Clinton on June 1, 2017, and the Quad Cities Generating Station in Cordova on June 1, 2018. Exelon says the locations are its best-performing plants but they have lost $800 million over the last seven years. About 1,500 people work at the plants. The company backs a measure that would extend state subsidies to nuclear power plants for producing reliable, carbon-free electricity that will help Illinois meet federal mandates. It says the future of the state legislation isn't clear after lawmakers formally adjourned their spring session Tuesday.