According to Inside EPA (subscription required), the Department of Justice (and the Sierra Club) have opposed Ameren’s Missouri’s motion to allow it to close its Rush Island generating facility early, rather than install otherwise required pollution control equipment. You may ask why DOJ is opposing the shutdown of a coal-fired power plant. Like Tevye in A Fiddler on the Roof, I’ll tell you. 
I don’t know.… More
I’m not sure it’s even really news at this point, but earlier this week Ameren Missouri announced that it would close its Rush Island Energy Center generating plant early, rather than spend the money to install flue gas desulfurization technology in response to an injunction issued after the District Court found that the Rush Island facility had violated the Clean Air Act. As Ameren noted in its filing with the Court:
Retiring Rush Island early will have a much more beneficial environmental impact,… More
The 8th Circuit Court of Appeals has largely affirmed a District Court order finding that Ameren Missouri violated the NSR provisions of the Clean Air Act in making major modifications to its Rush Island facility. 
The Appeals Court did reject the District Court’s requirement that Ameren Missouri make improvements at its nearby Labadie facility that was not in violation of the CAA.
I have three thoughts about the decision.… More
On Monday, District Judge Rodney Sippel ordered sweeping injunctive relief against Ameren Missouri, intended to remedy violations of PSD requirements he had previously identified resulting from upgrades to the Ameren Missouri Rush Island generating plant. 
Notwithstanding the lengthy opinion, most of the Court’s findings are fairly plain vanilla. Basically, Judge Sippel ordered Ameren Missouri to submit a PSD permit application and he ruled that BACT for control of SO2 emissions at Rush Island required installation of wet flue gas desulfurization equipment.… More
Late last month, Federal Judge Rodney Sippel ruled that EPA could obtain injunctive relief against Ameren Missouri in the long-running NSR enforcement case concerning Ameren’s Rush Island Plant. 
The Court had already ruled that Ameren had violated the Clean Air Act by failing to obtain a PSD permit prior to implementing substantial modifications at the plant.
Having lost at the liability stage, Ameren took three shots at avoiding injunctive relief. … More
Last Monday, in a comprehensive, 189-page opinion, Judge Rodney Sippel ruled that Ameren Missouri had violated EPA’s PSD regulations by failing to get permits for upgrades in 2007 and 2010 at its Rush Island facility. As I noted when Judge Sippel denied cross-motions for summary judgment, the result is not really a surprise.
Moreover, Judge Sippel’s decision is not based on any extreme reading of the law. … More
Given EPA’s recent run of defeats in its NSR enforcement initiative, it’s probably breathing a sigh of relief over last week’s decision in United States v. Ameren Missouri, regarding Ameren’s Rush Island coal-fired power plant. 
True, the court denied EPA’s motions for summary judgment. However, it also denied Ameren’s motions and on balance probably left EPA feeling better than Ameren about its prospects at trial. … More