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

The Honorable Geoffrey Standing Bear Principal Chief Osage Nation of Oklahoma 627 Grandview Avenue Pawhuska, Oklahoma 74056
Dear Principal Chief Bear: 

## MAR 2 0

## 2015

O F F ICE O F AI R A N D RAD I ATI ON

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 sulfur 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 designation s for the remainder of the country in separa te future actions.
On March 2, 2015 , the U.S. District Court for the Northern District of Ca li fo rnia accepted as an enforceable order an agreement between the EPA and Sierra C lub and Natural Re sources Defense Council to resolve litigation concerning the deadline fo r 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, unc lassifiable/attainment, or unclassifiable

. · In the first round of designations, the EPA wi ll des ignate two groups of areas: 1) areas that have newly monitored violations of the 2010 S02 s tandard, and 2) areas that contain any s tationary 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 em ission rate of at leas t 0.45 lbs S02/ mmbtu in 2012 and that has not been announced (as of March 2, 20 1 5) for retirement. In the enclosure to this letter, the EPA provides the schedule we intend to fo ll ow to meet the July 2, 2016 , deadline.
While there are cur rently no violating monitors and no sources meeting the above criteria on your tribal land , the EPA has identified the fo ll owing electric power plant source in Oklahoma as meeting the criteria established in the court's order. This source may potentiall y be impacting your tribal land :

S tate County Facili ty Name 2012 S02 Emissions 2012 S02 Emissions (tons) Rate (lb/mmBtu) OK Noble Sooner Generating 15,029 0.499 Station

I n ternet Ad dress ( URL) • h ttp ://www.epa

.g ov Recycled/Recyclable • P r i nted w i th Vege tab l e O i l B ased Ink s on 1 00% Postcon sumer

. P rocess Chlori n e Free Recycled PaperYou may wish to discuss the designat ion for this area with representatives of Oklahoma , and provide your own designation recommendation for the potentially affected area on your tribal l and . The E PA

will use the most recent available information when making area designation and boundary decisions for the indicated area. If you would like to submit in format ion or recomm e nda t ion s f or the potentially affected area on your tri bal land , we request that you do so by September 18, 2015. The EPA has updated its March 24, 20 II , designat ion guidance for the 2010 S02 sta ndard 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/sul[urdioxide/guidance.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. The se docum en t s can be found on the EPA's website at http :// epa.gov/airquality/sulfurdioxide /i mplement.html. T he court's order directs the EPA to complete the second round of area d esignations by December 31, 20 17. These designations would address areas where states have not installed and begun operating a new S02 monitoring network meeting the EPA ' s specifications referenced in our proposed rule tit led , " Data Requirements Rule for the 1-hour SOz primary NAAQS". This rule, which was proposed in the Federal Register on May 13 , 2014, would direct state and tri b a 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 sufficient air quality monitoring in place to identify maximum SOz concentrations. The data collected as a re su lt 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 wit h these la ter dead line s at a la ter date. We look forward to continued dialogue with you and your staff as we work together to implement the 2010 SOz sta ndard and achieve i ts intended public health pro tect ion. Fo r additional information re garding designations for the 2010 SOz standard, please visit o ur website at www.epa.gov / so2designations. Shou ld you have any questions, please do no t he sitate to call m e or Scott Mathias ofmy s taff at 919-541-5310 and mathias.scott @e pa.gov. Sincerely, Janet G. McCabe Acting Ass i stant Administrator Enc losur e

cc: Ron CurryEPA Region 6 AdministratorENCLOSURE
TIMELINE FOR 2010 PRIMARY S02 NAAQS DES IGNATION PRO CESS FOR AREAS ASSOCIATED 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 modification s to their than 120 days prior to final designations, i.e

. , recommendations ( 120-day letters) March 2, 20 1 6 The EPA publishes public notice of state o /a February 3, 20 16 recommendations and the EPA's intended modifications and ini tiates 30-day public comment period End of 30-day publ i c commen t period o/a March 4 , 20 16 States provide additional information to o/a April 8 , 20 16 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 duects the EPA to promulgate additiOnal rounds of designatiOns by December 31,2017 , and by December 31 , 2020. 

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