UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON , D

. C. 20460

The Honorable John Line Stine Commissioner Minnesota Pollution Contro l Agency 520 Lafayette Road N St. Paul , Minnesota 55155-4194
Dear Mr

. Stine: 

## MAR 2 02015

OF F ICE OF A I R AND RADIAT ION

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

. On March 2, 2015, the U

. S

. District Court for the Northern District of California accepted as an enforceable order an agreement between the EPA and Sierra Club and Natural Resources Defense Council to resolve litig ation 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 3 1, 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 of designations , the EPA will designate two groups of areas : 1) are as that have newly monitored vio lations of the 20 I 0 S02 standard, and 2) areas that contain any stationary source that according to the EPA's Air Ma rkets Database either emitted more than 16,000 tons of S02 in 2012 or emitted more than 2,600 tons of S02 and had an emission rate of at least 0.45 lbs S02/mmbtu in 2012 and that has not been announced (as of March 2, 2015) fo r retirement. In the enclosure to this letter, the EPA provides the schedule we intend to follow to meet the July 2 , 2016 , deadline.
While there are currently no violating monitors and no sources in Minnesota meeting the above criteria established in the court's order, the EPA has identified the fo llo wing electric power plant source in South Dakota as meeting the criteria established in the court's order, and may potentiall y be impacting your state :

I n terne t Ad dre ss {U R L) • h ttp : //

www

.epa

.gov Recycled/Recyclable • Pri n ted w i th Ve getable Oi l Based I nks o n 100% Postco n sume r , P r ocess C hl orine Free Recycled Paper20 12 S02 Em i ssions 20 12 S02 Emiss i ons Sta t e County Facility Name (tons) Rate (lb/mmBtu) SD Grant B i g Stone Plant
- Otte r 12,290 0.813 Tail Power Company You may wish to discuss the designation for this a r ea with representatives of South Dakota, and provide your own designation recomme n dation for the potentially affected area in your state. The E PA will use the most r ecent available information when making area designation and boundary decisions for the indicated area . If you would li ke to submit i nformation or recommendations for the

potentia ll y affected area in your state, we request that you do so by September 18, 2015 . The E PA has updated i ts March 24 , 20 1 1, designation guidance for the 2010 S0 2 standard to support analysis of designations and boundaries for these next rounds of designations. The updated guidance can be found on the EPA's websi t e at http :IIe pa. gov l airquality/sulfitrdioxidelguidance. html. The EPA has also provided two technical assistance docume n ts that prov i de adv i ce on the use of modeling and monitoring data when determining if an area is meeting or not mee t ing the 2010 S02 standard. These documents can be found on t he EPA's webs i te a t http://epa.gov/airquality/sul(urdioxide !impleme nt.html. The court 's o r der directs the EPA to complete the second round of area designations by December 3 l, 2017 . These des i gnations would add r ess areas where s tat es have not i nstalled a n d beg un operating a new S02 monitoring network meeting the EPA's specifications referenced in our proposed rule titled, "Data Req u irements Ru l e for the 1 - hour S02 primary NAAQS" . This rule, which was proposed in t h e Federal Register on May 13, 2014, would direc t state and tr i bal a i r agenc i es to provide data to charac t eri ze

current air q u ality i n areas with l arge sou r ces of S02 if such areas do not have suffic i ent a i r qua l ity mon i to r ing in place to identify maximum S0 2 concentrations. The data collected as a result of this proposed ru l e would be u sed in the designations process . Last l y, the court's order directs the EPA to designate all remaining areas by December 31, 2020 . The EPA wi ll provide states with additional i nformation on the designations process assoc i ated with these later deadlines at a later date. We look forward t o continued dialogue w i th you and your staff as we work together to implement the

20 1 0 S02 standard and achieve its intended public health protection. For addition a l information regarding designat i ons for the 2010 S02 standard , please v i s i t our websi t e at www.epa.gov/so2designations. Should you have any questions, please do not hesitate to ca ll me or Scott Ma t h i as of my staff at 9 1 9-54 1 -53 1 0 and mathias . scott@epa.gov . Sincerely, J anet G. McCabe Acting Assistant Admin i strator Enclosure cc: Susan Hedman

EPA Reg i on 5 AdministratorENCLOSURE
T IMELIN E FOR 2010 PRIMARY 

### SOz NAAQS DESIGNATION PROCESS FOR AREAS ASSO CIATED WITH JULY 2, 2016 , COURT-ORDERED DEADLINE* Milestone Date** Court Order March 2 , 20 15 States may submit updated recommendations No later than September 18 , 20 15 and supporting inf ormation for area designations to the EPA The EPA notifies states concerning any o/a January 22, 2016 , but abso lutel y no later intended modifications to their than 120 days prior to final designation s, 

### i.e. , recommendations ( 120-day letters) March 2, 20 16 The EPA publishe s public notice of state o/a Febru ary 3, 2016 recommendation s and the EPA 's intended modifications and initiates 30-day publ ic comment period End of 30

-day public comment period o /a March 4 , 20 16 States provide additiona l info rmati on to o/a April 8 , 2016 demonstrate why an EPA modification is inappropriate The EPA promulgates final 

### SOz area No later than July 2, 2016 designations (no late r than 16 months from Court Order) * The court' s order directs the EPA to promulgate additional ro unds of desig nations by Decem ber 31 , 20 17, and by December 31, 2020. 

## ** o/a = on or about