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

The Honorable Chuck Gipp Director Iowa Department ofNatural Resources Wallace State Office Building 502 East 9th Street 4111 Floor 

### ' Des Moines, Iowa 50319

-0034
Dear Mr. Gipp : 

## MAR 202015

OFFICE OF AIR AND RADIATION

I am writing to update you onthe 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, 2017, and the final round by December 31 , 2020

. The EPA will complete these designations by designating areas as either nonattainment, unclassifiable/atta inment, or unclassifiable.
In the first round ofdesignations, the EPA will designate two groups ofareas: I) areas that have newly monitored violations ofthe 20I0 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 of

### SOz in 2012 or emitted more than 2,600 tons ofS02 and had an emission rate ofat least 0.45 lbs S02/mmbtu in 20I2 and that has not been announced (as ofMarch 2, 20 15) for retirement. In the enclosure to this letter, the EPA provides the schedule we intend to follow to meet the July 2, 2016, deadline.
The EPA has identified the following electric power plant sources in your state as meeting the criteria established in the court's order:

InternetAddress (URL) • http://www.epa.gov Recycled/Recyclable • Printed with Vegetable Oil Based Inks on 100% Postconsumer, ProcessChlorine Free Recycled Paper2012 so 2 2012 S02 S tate County Faci lit y Name Emissions Emiss ions Rate (tons) (lb / mmbtu) I A Wapello Ottumwa Generatin g Station 11 , 985 0.666 l A De s Moine s Burlington Gener ati n g Sta tion 4,697 0.672 l A Wood b ur y George Neal Station So uth 14 ,273 0.638

Th e E P A w ill use the most recent available information whe n making designation an d boundary decisions for th e indicated areas . If you would lik e to s ubmit updated r ecommendat ions and supporting in form ation for the E PA to consider for the aff ecte d a re as in your state, we request that you do so by Se ptember 18 ,2015 . In ad dition, the EPA h as id e ntified th e followin g e l ectr ic power plant source in the neighboring s tate of Neb r aska that also m eets the c riteria established in the court's order , and m ay potentially be impac t in g your state: 2012 so 2 2012 so2 State County Facility Name Emissions E mi ss ions R ate (tons) (lb/mmbtu) NE Otoe Ne braska City Station 1 6,766 0.354 You may wish to discu ss the designation for thi s a r ea with representative s of Ne b raska and provid e your own designation recommendation for the potenti a ll y affec ted area in your s t ate. Again, please pro vide any in format ion you would like us t o consider by Se pt embe r 18 , 2015. The E P A has updated it s Ma rch 24, 2011, designation guida nce for the 20 I 0 SCh standar d to s upp ort analys i s of de s i g nati ons and boundaries for th ese n ext rounds of designati ons. T h e updated guidance can be found on the EPA ' s website at http :/ / epa.gov / airquality/s ul[urdioxid e l guidance. html. The EPA has

a l so provided two technical assistance document s th a t provide advice on the use of modeling and moni t or i ng data when determining if an area is m ee ting or not meeting the 2010 S0 2 standard. The se d oc uments can be found on the EPA's website at hllp :l/ e pa.gov l airquality / su l[urdioxide / implem ent.h tml . T h e court's order directs the E P A to complete the second round of area designat i o n s by Decemb er 3 1 , 2017. These designations would address areas where sta t es have not installed an d begun operating a new S0 2 monitorin g network meeting the EPA 's specificat i ons referenced in our proposed rule titled, " Data Requirements Rul e fo r the !-hour S02 primar y N AAQS". This rule , which was proposed in the Federal R egister on May 13 , 2014 , would d i rect state and tribal air agencies to provid e data to characterize c urr en t air quality in a r eas with large sources of S02 i f such areas do n o t have s ufficient air quality moni to rin g in place to id e ntify maximum S02 concentrations. The data collecte d as a result of this proposed rule would be u sed in the designation s process. Las tly, the court's or der directs the EPA to des i gnate all rem a inin g a r eas by D ecember 31, 2020. The EPA will pro vide states with additional information on the d esignations process associated wit h these la ter d eadli n es at a l ater date.We look forward to continued dialogue with you and your staffas we work together to implement the 20I0 S02 standard and achieve its intended public health protection. For additional information regarding designations for the 2010 S02 standard, please visit our website at 

### www.epa
.gov!w2designations. Should you have any questions, please do not hesitate to call me or Scott Mathias ofmy staffat 919-541-5310 and 

### mathias.scoll@epa.gov. Sincerely,

Janet G. McCabe Acting Assistant Administrator
Enclosure

cc: Mark Hague EPA Region 7 Acting Administrator

### ENCLOSURE
TIMELINE FOR 20 10 PRIMARY S02 NAAQS DESIGNATION PROCESS FOR AREAS ASSOCIATED WITH JULY 2, 2016, COURT-ORDERED DEADUNE* 

### Milestone Date** Court Order March 2, 2015 States may submit updated recommendations No later than September 18, 2015 and supporting information for area designations to the EPA The EPA notifies states concerning any o/a January 22, 2016, but absolutely no lat er intended modifications to their than 120 days prior to final designations, i.e. , 

### recommendations ( 120-day letters) March 2, 2016 The EPA publishes public notice ofstate o/a February 3, 2016 recommenda tions and the EPA's intended modifications and initiates 30-day public comment period End of30-day public comment period o/a March 4, 20 16 States provide additional informationto o/a April 8, 2016 demonstrate why an EPA modification is inappropriate The EPA promulgates final S02 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.
** o /a 

### = on or about