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

The Honorable Clifford Wolfe, Jr. Cha irman Omaha Tribe ofNebraska P.O. Box 368 Macy, Nebraska 68039
Dear Chairman Wolfe: 

## MAR 202015

O FFICE OF A I R AND RADIATI 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 designations for the remainder ofthe country in separate future actions

. On March 2, 2015, the U.S. District Court for the Northern District ofCalifornia 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, 20 17, 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 ofthe 2010 S02 standard, and 2) areas that contain any sta tionary 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 0.45 lbs S02/rnmbtu in 20 12 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.
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 Iowa as meeting the criteria established in the court's order. This source may potentially be impacting your tribal land:

State County Facility Name 2012 S02Emissions 2012 S02 Emissions (tons) Rate (lb/mmBtu) lA Woodbury George Neal 14,273 0

.638 Station South

Internet Add ress (U RL) • http: //

www

.epa.gov Recycled/Recyc lab le • Printed with Vegetable O il Based Inks o n 100% Postconsumer, Process Chlorine Free Recycled PaperYou may wish to discuss t h e des i gnat i on for this area wit h representatives of Iowa , and prov i de your own designation recomme n dation for the potentially affected area o n your t r i bal l and. The EPA will use t he most recent available informa t ion when making area designation and boundary decisions for t he indicated area . If you would l ike t o submi t information or recommenda t ions for the po t entially affected area on your tr i ba l l and, we req u est that you do so by September 18 ,2 015. The EPA has updated its March 24, 20 1 1, designation gu i dance fo r the 201 0 S02 standard to s u pport analysis of designations and boundaries for these next rounds of designat i ons . T he updated gu i dance can be found o n the EPA's webs i te at http :// epa.gov/airquality lsulfu rdioxide lgu idance . html . The EPA has also provided t wo t echnical assistance documents that provide advice on the use of modeling and

mo ni tor i ng data when determining if an area i s meeting or not meeting the 2010 S02 s t andard. These doc u men t s can be found on the EPA's website a t http ://e pa.gov lair quality ls ulfurdioxide l implement.html. The court's order directs the EPA to complete the second round of area des i gnat i ons by December 31 , 2017. These designat i ons would address areas where sta t es have not ins t alled and begun operating a new

S02 monitor i ng netwo r k meeting the EPA's specifications r eferenced in our proposed rule titled, "Data Requirements Rule for the 1- hour S02 primary NAAQS" . Th i s rule, wh i ch was proposed in the Federal Register on May 13, 2014, would direct state and tr i bal a i r agenc i es to prov i de data to charac t erize c u rrent a i r quality in areas wi t h large sources of S02 if such areas do n ot have sufficient a ir quality monitor i ng in place to i den t ify maximum S02 concentrations. The data collected as a r esu l t of this proposed rule would be used in the designat i ons p r ocess . Las tl y, the court 's order direc t s the EPA to des i gnate all remaining areas by December 31, 2020. The EPA will provide states with add i t i o n a l information on the designations process assoc i ated with these l ater dead l ines a t a l ater date . We look forward to continued d i a l ogue w i th you and your staff as we work t ogether to implement the 2010 S02 standard and achieve i t s intended public health protection . For add i tional information regardi n g designations for the 20 I 0 S02 s t andard , please visit our website at

www . epa.gov/so2designations. Sho ul d yo u have any ques t ions, please do not hesitate to ca ll me or Scott Mathias of my staff at 919
- 541
- 5310 and mathias. s cott @ep a.gov . Sincerely, Janet G . McCabe Ac t ing Assistant Administrator Enclosu r e cc : Mark Hag u e EPA Region 7 Acting Administrato r

### ENCLOSURE

TIMELINE FOR 2010 PRIMARY 

### SOz NAAQS DESIGNATION PROCESS FOR AREAS ASSOCIATED 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, 2015 and supporting information for area designa tions to the EPA 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 letters) March 2, 20 16 The EPA publishes public notice of state o/a February 3, 2016 recommendations and the EPA' s intended modifications and initiates 30-day public comment period End of30

-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 promulga tes final 

### SOz area No later than July 2, 20 16 designations (no later than 16 months from Court Order)

. . 

## * The court's order directs the EPA to promulgate addttlonal rounds ofdestgnatwns by December 31, 2017, and by December 31 , 2020. 

## ** ol a =on or about