The Honorable Michael R. Pence 

Governor of Indiana 

200 W. Washington St., Rm. 206 Indianapolis, IN 46204 

Dear Governor Pence: 

Thank you for your recommendations dated September 16, 2015 on air quality designations for the State 

oflndiana for the 2010 revision to the primary National Ambient Air Quality Standard (NAAQS) for 

sulfur dioxide (S02). Reducing levels of S02 pollution is an imporiant part of the U.S. Environmental 

Protection Agency's commitment to a clean, healthy environment. Exposure to S02 can cause a range 

of adverse health effects, including narrowing of the airways which can cause difficulty breathing and 

increased asthma symptoms. This Jetter is to notifY you ofEPA's preliminary intentions regarding your 

recommended designations. 

On June 3, 201 0, EPA strengthened the health-based or "primary" standard for S02 by establishing a 

standard for 1-hour average S02 concentrations at a level of 75 parts per billion. Within one year after a 

new or revised standard is established, the Clean Air Act requires the Governor of each state to submit 

to EPA a list of all areas in the state, with recommendations for whether each area meets the standard. 

Through an interactive process, EPA considers the recommendations and then promulgates designations 

for all areas across the country. On July 25,2013, EPA designated 29 areas in 16 states as 

nonattainment based on monitored violations, but did not at that time designate other areas. Pursuant to 

a March 2, 2015, court-ordered schedule, I EPA must complete the remaining so2 designations by three 

specific deadlines: July 2, 2016, December 31, 2017, and December 31, 2020. 

This current round of designations, to be completed by July 2, 2016, addresses two groups of areas: (1) 

areas that have newly monitored violations of the 2010 S02 NAAQS based on the most recent three 

calendar years of certified monitored ambient air quality data, and (2) areas that contain any stationary 

source that had not been announced as of March 2, 2015, for retirement and that according to EPA's Air 

Markets Database emitted in 2012 either (i) more than 16,000 tons of S02 or (ii) more than 2,600 tons of 

S02 with an annual average emission rate of at least 0.45 pounds of S02/MMBTU. 

1 Sierra Club v. McCarthy, No. 3-13-cv-3953 (Sl) (N.D. Cal. Mar. 2, 2015). 

Recycled/Recyclable • Printed with Vegetable Oil Based Inks on 100% Recycled Paper (1 00% Post-Consumer) 
Intended Unclassifiable/ Attainment Area 

Gibson County 

LaPorte County 

Spencer County 

Intended Unclassifiable/ Attainment Area Counties 

Gibson County 

LaPorte County 

Spencer County (p )* 

The asterisk (*) indicates a modification to the designation that you have recommended. The (p) 

indicates only a portion of the county will be designated. 

In the case of Jefferson and Posey Counties, we have been working with your staff toward establishing 

federally enforceable emission limits that would support designations of unclassifiable/attainment for 

relevant portions of these counties. The commissioner oflndiana's Department of Environmental 

Management issued orders imposing state enforceable limits on the pertinent sources, issued on 

January II, 2016 and February 1, 2016. We have been working with the Department toward EPA 

approval of these orders, so that they may be creditable for our final designation. The enclosed 

Technical Support Document (TSD) concludes that if these orders become federally enforceable in a 

timely fashion, EPA anticipates that it would designate suitable portions of these counties as 

unclassifiable/attainment. While our present intent is to designate one township in each of these 

counties as nonattainment, we believe federal enforceability of the orders would support designating 

more substantial portions of these counties as unclassifiable/attainment, as detailed in the enclosed TSD. 

The enclosed TSD provides a detailed analysis that supports our intended designation decisions. If your 

state has additional information that EPA should consider prior to finalizing these designations, please 

submit it to us by April19, 2016. We also will be publishing a notice in the Federal Register 

announcing a 30-day period for the public to provide input on EPA's intended designation decisions. 

We will promulgate the designations for these areas by July 2, 2016. We will designate all other 

previously undesignated areas in the state on a schedule consistent with the prescribed timing of the 

court order, i.e., by December 31, 2017, or December 31, 2020. 

We look forward to a continued dialogue with you and your staff as we work together to complete the 

area designations and implement the 2010 primary S02 standard. For additional information regarding 
Acting Regional Administrator 

Enclosure 

cc: CarolS. Comer, Commissioner 

Indiana Department of Environmental Management 

Keith Baugues, Deputy Assistant Commissioner 

Office of Air Quality 

Indiana Department of Environmental Management