On July 10, 2011, U.S. EPA disapproved the portions of Indiana’s and Ohio’s state implementation plans (“SIPs”) addressing interstate transport for the 2006 twenty-four hour PM2.5 National Ambient Air Quality Standard (“NAAQS”). 

In disapproving of the interstate transport SIPs, EPA argued that it required the SIPs to specifically address the Clean Air Act provision requiring states to not “interfere with maintenance” of NAAQS in downwind states.  EPA said it further told the states that they could not rely on the Clean Air Interstate Rule (“CAIR”) standards because CAIR did not address this NAAQS.  EPA argued that both Indiana and Ohio wrongly relied on CAIR in their proposed SIPs.

Indiana’s response was that its submission could not be disapproved for relying on CAIR because CAIR was the only guidance upon which states could rely.  The Cross-State Air Pollution Rule had not been proposed before Indiana was required to submit its SIP.  Indiana indicated in its proposal that it would amend its SIP once the Cross-State Air Pollution Rule was finalized.  EPA felt that Indiana should have relied on its own technical analysis rather than on CAIR.  EPA felt that even under Indiana’s SIP, pollution from Indiana plants  interfered with the ability of downwind states to maintain their own NAAQS.  EPA based its decision on its own modeling done in support of the Cross-State Air Pollution Rule.

Ohio’s response was that its SIP was adequate based on the best guidance available from EPA.  Ohio contended that EPA should have issued a SIP deficiency and allowed Ohio to issue a new SIP once the Cross-State Air Pollution Rule was final.  EPA did not believe Ohio’s SIP was adequate and felt constrained by statute to disapprove it.

Where will the parties go from here?  Within two years of disapproving a SIP, EPA is required to promulgate a federal implementation plan.  EPA intends the federal implantation plans promulgated with the new Cross-State Air Pollution Rule to play this role.  Indiana and Ohio can also submit a new SIP at any time.  The rest of Indiana’ and Ohio’s 2006 twenty-four hour PM2.5 NAAQS not dealing with interstate transport are not affected by EPA’s action.