UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460

The Honorable Gary Rikard Executive Director 

## MAR 202015

Mis sissippi Department ofEnvironmental Quality P

.O. Box 2261 Jackson , Mississippi 39225
Dear Mr. Rikard: OFFICE OF A I R AND RADIATION

I am writing to update you on the status ofthe U.S. Environmental Protection Agency's progress in implementing the primary National Ambient Air Quality Standard (NAAQS) for sulfhr dioxide (S02 ) set in 2010 at 75 parts per billion (ppb) as a 1-hour average. In July 2013, the EPA identified areas in 16 states as nonattainment and expressed the intent to address designations for the remainder ofthe country in separate future actions.
On March 2, 2015, the U.S

. District Court for the Northem District ofCalifomia accepted as an enforceable order an agreement between the EPA and Sierra Club and Natural Resources Defense Council to resolve litigation concerning the deadline for completing the designations. The court' s order directs the EPA to complete designations in three additional rounds: the first round by July 2, 2016, the second round by December 31, 2017 , and the final round by December 31 , 2020

. The EPA will complete these designations by designating areas as either nonattainment, unclassifiable/attainment, or unclassifiable

. In the first round ofdesignations, the EPA will designate two groups ofareas : 1) areas that have newly monitored violations of the 2010 S02 standard, and 2) areas that contain any stationary source that according to the EPA ' s Air Markets Database either emitted more than 16,000 tons ofS02 in 2012 or emitted more than 2,600 tons ofS02 and had an emission rate ofat least 0.45lbs S02/ mmbtu in 2012 and that has not been announced (as ofMarch 2, 2015) for retirement. In the enclosure to this letter, the EPA provides the schedule we intend to follow to meet the July 2, 2016, deadline.
The EPA has identified the following electtic power plant source in your state as meeting the criteria established in the court' s order:

2012 so2 20 12 so2 State County Facility Name Emissions Emissions Rate (tons) (lb/mmbtu) R D MmTow Senior MS Lamar Generating Plant 3 ,948 0.627

Internet Address (URL) • httpJ/www.epa.gov Recycled/Recyclable • Printed wi th Vegetable O il Based Ink s on 100% Postconsumer, Process Ch lorine Free Recycl ed PaperThe EPA will use the most recent available information when making designation and boundary decisions for the indicated area. If you would like to submit an updated recommendation and supporting information for the EPA to consider for the affected area in your state, we request that you do so by

September 18 , 2015. The EPA has updated its March 24, 2011, designation guidance for the 2010 S02 standard to support analysis of designations and boundaries for these next rounds of designations. The updated guidance can be found on the EPA's website at http :// epa.gov/airqualitv!sulfitrdioxidelguidance . html. The EPA has also provided two technical assistance documents that provide advice on the use of modeling and monitoring data when determining if an area is meeting or not meeting the 2010 S02 standard. These documents can be found on t he EPA's website at http://epa.gov/airqualitvlsul(urdioxide/implement.html. The court's order directs the EPA to complete the second round of area designations by December 31, 2017 . These designations would address areas where states have not installed and begun operating a new

S0 2 monitoring network mee t ing the EPA ' s specifications referenced in our proposed rule titled , "Data Requ i rements Ru l e for the 1-hour S02 primary NAAQS" . This rule, which was proposed in the Federal Register on May 13, 2014, would direct state and tribal air agencies to provide data to characterize

current air quality in areas with large sources of S02 if such areas do not have sufficient air quality monitoring in place to identify maximum S02 concentrations. The data collected as a result of this

proposed rule would be used in the designations process. Lastly , the court ' s order directs the EPA to designate all remaining areas by December 31 , 2020. The EPA will provide states with additional information on the designations process associated with these later deadlines at a later date . We look forward to continued dialogue with you and your staff as we work together to implement the

20 l 0 S02 standard and achieve its intended public health protection. For additional information regarding designations for the 2010 so2 standard, please visit our website at www.epa.gov / so2designations. Should you have any questions, please do not hesitate to call me or Scott Mathias of my staff at 919-541-5310 and mathias.scott @ epa.gov . Sincerely , Janet G . McCabe Acting Assistant Adm i nistrator Enclosure cc: Heather McTeer

EPA Region 4 AdministratorENCLOSURE
TIMELINE FOR 2010 PRIMARY S02 NAAQS DESIGNATION PROCESS FOR AREAS ASSOCIATED WITH JULY 2, 2016, COURT-ORDERED DEADLINE* Milestone Date** Court Order March 2, 2015 States may submit updated recommendations No later than September 18, 2015 and supporting information for area designations to the EPA The EPA notifies states concerning any o/a January 22, 2016, but absolutely no later intended modifica tions to t heir than 120 days prior to final designations , 

### i.e., recommendations ( [ 20-day letters) March 2, 2016 The EPA publishes public notice ofstate o/a February 3 , 2016 recommendations and the EPA's intended modifications and initiates 30

-day public comment period End of 30

-day public comment period o /a March 4, 2016 States provide additional information to o /a April 8, 2016 demonstrate why an EPA modification is inappropriate The EPA promulgates final S02 area No later than July 2, 2016 designations (no later than 16 months from Court Order) * The court's order directs the EPA to promulgate additional rounds ofdesignations by December 31 , 2017 , and by December 31,2020

. ** o /a = on or about