UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON , D

.C

. 20460



### The Honorable Bill John Baker Principal Chief Cherokee Nation of Oklahoma P.O. Box 948 Tahlequah, Oklahoma 74465 Dear Principal Chief Baker: 

## MAR 2 02015

O F F ICE OF A I R A N D RA DI ATION



### I am writing to update you on the status of the U.S. Environmenta l 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 1-hour average. In July 2913, 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 S ierra C lub 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 of designations , the EPA will designate two groups of areas : 1) areas that have newly monitored violations ofthe 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 of at least 0.45 lbs 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 schedu le we intend to follow to meet the July 2, 2016, deadline. While there are currently no violating monitors and no sources meeting the above criteria on your tribal land, the EPA has identified the following electric power plant source in Oklahoma as meeting the cr

iteria established in the court's order. This source may potentially be impacting your tribal land:
State County Facility Name 2012 

### SOz Emission s 20 12 S02 Emissions (tons) Rate (lb/mmBtu) Muskogee Generating OK Muskogee Station 22,647 0.496

Internet Address (U R L) • http://www.epa

.gov Re cycled/ Recy clable • Prin ted w ith Vege tabl e Oil Based Inks on 1 00% Pos tconsumer. Process Chlori ne F ree Recyc l ed Pape rYou may wish to discuss the designation for this area with representatives of Oklahoma , and provide your own designation recommendation for the potentially affected area on your tribal land. The EPA

will use the most recent ava il able i nformation when makin g area designation and boundary decisions for the indicated area. If you would like to submit information or recommendations for the potentially affected area on your tribal land, we request that you do so by September 18 , 2015. The EPA has updated its March 24, 2011 , des i gnation guidance for the 20 I 0 S02 standard to support analysis of designations and boundaries for these next rounds of des i gnations. The updated guidance can be found on the EPA ' s website at http :// epa.gov / airquality / sulfurdioxide l guidance.html . The EPA has also provided two technical ass i stance documents that provide advice on the use of modeling and monitoring data when determin in g i f an area is meeting or not meeting the 201 0 S02 standard. These documents can be found on the E PA's web s ite at http :// epa . gov / airquality l sulfurdioxide l implement.html. The court's order d i rects the EPA to comp l ete th e second round of area designations by December 31, 2017. These designations would address areas where states have not ins t a ll ed and begun operating a new

S02 monitoring network meeting the E PA ' s specifications referenced in our proposed ru l e t i tled, "Data Requ i rements Ru l e for the !-hour S02 primary NAAQS". This rule, which was proposed in t he Federal Register on May 1 3 , 20 1 4, would direct state and triba l air agencies to provide data to characterize

current air quality in areas with large sources of S02 if such areas do no t have su f ficient air quality monitoring in place to identify maximum S02 concentrations. The data co ll ected as a r e sult of t his

proposed rule would be used in the designat i ons process. Lastly, the court's order directs the E PA to designate all rema i ning areas by December 3 1 , 2020. The EPA w ill provide states with additional inf ormat i on on the designations process as s ociated with these later deadlines at a later date . We l ook forward to continued dialogue with you and your staff as we work together t o implement the 2010 S02 standard and achieve its intended public health pro t ection . For additional information regarding designations for the 201 0 S02 standard, please visit our website at www . epa.gov / so2designations. Should you have any questions , please do not hesitate to ca ll me or Scott Mathias of my s t aff a t 919 - 541-5310 and mathias.scott @ epa . gov . Sincerely, Janet G . McCabe Acting Ass i s t ant Adm i nistrator Enclosure cc: Ron CurryEPA Region 6 Adminis t rator

### ENCLOSURE
TIMELINE FOR 2010 PRIMARY S02 NAAQS DESIGNATION PRO CESS FOR AREAS ASSOC IATED WITH JULY 2, 2016, COURT-ORDERED DEADLINE* Milestone Date** Court Order March 2 , 20 1 5 States may submit updated recommendations No later than September 18 , 2015 and supporting information for area designations to the E PA The EPA notifies states concerning any o/a January 22, 2016 , but absolutely no later intended modifications to their than 120 days prior to final designations , i.e ., recommendations ( 120-day let ters) March 2, 20 1 6 T he EPA publis he s publi c notice of state o/a February 3, 2 01 6 recommendation s 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 addi tional informat ion to o/a April 8, 2016 demonstrate why

- an EPA modification is inappropriate The EPA promulgates fi n a l S02 area No later than July 2, 20 16 designations (no later tha n 16 mont h s f rom Court Order)

.. * The court's order d irects the EPA to promulgate addttiOnal rounds of destgnat10ns by December 31, 2017 , and by December 31, 2020. ** o/a = on o r about