[Ben Ficklin]

Congress passed New Source Review in the 70s and it has been in and out of court until 2007 and the SCOTUS decision which was thought to be the last.

Bush declined to implement, punting it to the next prez. Bush knew the enviros wouldn't sue him because he would be out of office in 18 months.

The issue has always been about maintenance. It's obvious that a new plant would face the revue, but industry used maintenance of existing plants to increase the capacity of the existing plants, avoiding the revue.

So now the enviros are going after them and it is not economically reasonable for industry to go back and retrofit the older/smaller plants.

[Eric in the Ozarks]

I happen to know that one of the targeted power plants has received a demand to upgrade to best available technology based solely on the repair of a steam line.
New Source was initially designed to cover expansions, not maintenance.
I've been in the energy biz since 1980 and am aware of the history of NSPS.