The Intermountain Power Agency said Wednesday that it will allow its air-quality permit for third coal-fired power generation unit at the Intermountain Power Project to expire.

The action effectively kills the controversial facility that was proposed to be built at the plant near Delta. Utah environmental advocates had long criticized the proposal as another potential source of pollution. The Utah chapter of the Sierra Club appealed the permit.

IPA spokesman John Ward told the Deseret News that the Unit 3 air permit had been on hold for more than a year while IPA, the Los Angeles Department of Water and Power and the Utah Associated Municipal Power Systems fought a legal battle over the proposed 900-megawatt power generating station. IPA and UAMPS had sued the California utility for breach of contract after it pulled out of its agreement to purchase electricity from the plant. That suit was settled last month, he said.