UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON , D

. C. 20460



## MAR 2 02015

The Honorable Cathy Stepp Secretary Wiscons in Department of Natural Resources 101 S

. Webster Street Madison , Wiscons in
Dear Ms. Stepp: OFF I C E OF AIR AN D RAD IATION

I am writing 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 1-hour average. In Jul y 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 fo r 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 litigation conc erning the deadline for completing the designations. The court 's order directs the EPA to complete designations in three additional rounds: the first round by Ju ly 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 , unclass ifiab le/attainment, or unclass ifiable.
In the firs t round of designations , the EPA will designate two groups of areas: 1) areas th at have newly monitored violati ons of the 2010 S02 standard, and 2) areas that contain any stationary source that according to the EPA's Air Markets Da tab ase either emitted more than 1 6 , 000 to ns ofS02 in 2012 or emitted more than 2,600 tons of S0 2 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) for retirement. In the enclosure to this letter, the EPA provides the schedule we intend to follow to meet the July 2, 20 16 , deadline

. The EPA has identified the following area in your state as one that may have a newly recorded violation of the 2010 S02 standard based on preliminary air quality monitoring data collected between 2012 and 2014:
S tate County Air Quality Monitor Location 2012

- 2014 Systems Monitor Preli minary S02 Identification Number Design Value (ppb) WI Brown 55

- 009

- 0005 East High , 76 14 15 E. Walnut Green Bay , WI 54301

I n ternet Add r ess ( U R L) • http :/ / www

. epa.gov Recycle d/Recyc lable • P r i nted wi th Vegetab l e O i l B as e d Ink s o n 100 % Postco n sume r , P r ocess C hl orine Free Recycled PaperThe EPA has a l so identified the fo llowing e lectr ic power plant source in your state as meeting the criteria established in the court's order: 2012 S02 2012 S02 State County F acility Name Emissions Emissions Rate (tons) (lb / MMBtu) WI Co lumbi a Columbia Energy Center 24,599 0.597 The E PA will use the most recent available information when making designation and boundary decisions for the indicated areas. If you would like to submit updated recommendations and s upport ing information for the EPA to consider for the affected areas in your state, we request that you do so by

September 18 , 20 1 5 . The EPA has updated its March 24, 2011, designation guidance for the 2010 S02 sta nd a rd to support analysis of designations and boundaries for these next rounds of designations. The u pd ated guidance can be found on the E P A's website a t http :/ /epa . gov/airquality / sulfurdioxide / guidance . html. The EPA has

a l so provided two techn i cal assistance documents that provide advice on th e use of modeling and monitoring data when determining if an a r ea is meeting or not meeting the 2010 S02 standard. These documents can be found on the EPA's webs ite at http: // epa.govlairquality l sulfurdioxide / implement.html. The court's order directs the EPA to comp le te the second round of area designations by December 31 ,

20 17. T hese designations would address areas where s tat es have not installed and begun operating a new S02 monitoring network meeting the EPA's s peci ficat ion s referenced in our proposed rule titled, "Data Requirements Rule for the 1 - hour S02 primary NAAQS". This rule , which was p roposed in the Federal Register on May 13,2014, would direct state and tr ibal air agencies to provide data to characterize

current air qua li ty in areas with large sources of S02 if such areas do not have sufficie n t air qua li ty 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 w i th these later deadlines at a later date. We look forward to continued dialogue with you and your staff as we work together to i mplement the 2010 S02 standard and achieve its intended p ub lic heal th protection. Fo r additional information regarding designa t i ons 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 Ac t in g Assistant Administrator Enclosure cc: Susan Hedman EPA Region 5 AdministratorENCLOSURE
TIMELINE FOR 20 10 PRIMARY S0 2 NAAQS DESIGNATION PROCESS FOR AREAS ASSOCIATED W I TH JULY 2, 20 16 , COUR T-ORDERED DEAD LIN E* Milesto ne Date** Court Order March 2, 20 15 S t

ate s may submi t updated reco mmendati o n s No later than September 18, 2015 and s upp orting information fo r are a designation s to the EPA The EPA notifies states concernin g any o/a January 22 , 201 6 , but absolutely no later intended modifications to their than 120 days prior to final des ignations , i.e., re co mmendations ( 1 20-day letters) March 2 , 2016 The EPA publi shes publi c notice of state o/a February 3 , 20 1 6 rec ommendations and the EPA 's intended modificati ons and initiates 30-day public comment p eriod End of 30 -day public comment period o/a March 4, 2016 States p rovide addi tional inf o rm ati on to o/a April 8, 20 1 6 demon strate why an EPA modification i s inappropriate The EPA promulgates final S02 area No later than July 2 , 201 6 designations (no later than 16 months from Court Order)

.. *The court's order dtrects the EPA to promulgate add1 t10 n al rounds of destgnatwns by December 3 1 , 2017, and b y December 31 , 2020. 

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