UNITED STATES ENVIRONMENTAL PROTECTION AGENC Y WASHINGTON , D

. C

. 20460

The Honorable Martha E. Rudolph Director 

## MAR 2 02015

Colorado Depar tment of Public Health and Environment 4300 Cherry Creek Drive Sou th Denver, Colorado 80 246
Dear Ms

. Rudolph: OFFICE OF AIR AND RADIATION

I am writing to update you on the status of the U.S. Environmental Protection Agency's progress in impl ementi ng the primary National Ambient Air Quality Standard (NAAQS) fo r su lfur dioxide (S02) set in 20 I 0 at 75 parts per billion (ppb) as a !-hour average. In July 20 1 3 , the EPA identified areas in 16 s tate s as nonattainment and expressed the intent to add ress designations for the remainder of the country in se parate futu re action s . On Ma rch 2, 2015 , the U.S. D istrict Court for the Northern District of Cal ifornia accepted as an enfo rceable order an ag reemen t between the EPA and S ier r a Club and Natural Reso urc es Defense Council to resolve liti gation concerning the deadline fo r completing the designations. T he court's orde r directs the EPA to complete designati ons in three additiona l rounds: the first round by July 2, 2016, the second round by Decemb er 31 , 20 1 7 , and the final round by December 31, 2020. The EP A will comp le te these desi gna ti ons by de signat ing areas as either nonattainment , uncla ss ifiable / attainment , or uncla ssi fiable.
In the first round of d esignat io ns, the EPA will des igna te two g roups of areas: I) areas that have ne wly monitored violations of th e 20 I 0 S02 standard , and 2) areas that contain any s tationary source that according to the EPA's Air Markets D a tabase either em itted more than 16,000 tons ofS02 in 2012 or emi tted more than 2 , 600 tons of S02 and had an emission rate of at least 0.45 lb s S02 /mmbtu in 2012 and that has not been announced (as ofMarch 2, 20 1 5) for ret irement. In the enclosure to this Jetter , the EPA provides the schedule we intend to follow to meet the Jul y 2, 2016, deadli ne. T h e EPA has identified the fo ll owing electric pow er plant sources in your state as meeti n g the criteria es tablished in the court' s ord er:
2012 S02 2012 S02 S tate County Facility Name Emissions E missions R ate (tons) (lb/ mmbtu) 

# co El Paso Martin Drake P ower P lant 4 ,792 0.565 

## co Mo rg an Pawnee· Generating s tation 

### 13 ,510 0.762

I n terne t Ad dress ( URL) • http ://w ww
. epa
. gov Recycled/Recyclable • Printed w i t h Vege ta bl e Oil Based I nk s on 1 00% Po stcon sum er. Process Chlo rin e F r ee Recyc l ed Pape rThe EPA w ill use the most recent available information wh en making designati o n and boundary decisions for the indicated areas. If you would like to submit an updated recomm endat i o n and supporting information for the EPA to consider for the affected areas in your state , we request that you do so b y September 18 ,20 15. The EPA h as updated its March 24, 2011, designation guidance for the 2010 S02 standa rd to s upp ort analysis of de sig nations and boundaries for th ese next rounds of designations. The updated gu i d ance can be found on the EPA's website at htLp:l/epa.gov!airqualitv!sul{urdioxide/guidance.html. The E P A h as also provid ed two technical assistance documents that provide advice on the use of modeling and monitoring data when determinin g if an area i s meeting or not meet i ng the 2010 S0 2 standard. T he se documents can be found on the EPA's webs it e at hllp :l! epa.gov / airqualitv/sul{urdioxide l implement .htm/. The court's order directs the EPA to complete the second round of area designati ons by Decemb e r 31, 2017. These designations would address areas where states have not installed and begun operating a new

S02 monitoring network meetin g the EPA's specifications referenced in our propo se d rule titled, " Data Requirement s Rule for the !-h o ur S02 primar y NAAQS". This rule, which was proposed in the Federal Regist e r on May 1 3, 2014, wou ld direct state a nd triba l air agencies to pro vi de data to characterize current air quality in areas with large sources of S02 if such areas do not have suffic i ent air quality monitorin g in p l ace to ident i fy maximum S02 concentrations. The data collected as a result of this proposed rul e would be us ed in the designati o n s process. La s tl y, the cou1t's order directs the E P A to designate a ll remaining areas by December 31 , 2020. The EPA will provide states with additional information on the designation s process associated with these later deadlines at a later date. We look forward to continued dialogue with you and your staff as we work together to implement the 2010 S02 standard and achi eve its intended public health prot ec ti on. For addition a l information regarding d esignatio ns for th e 2010 so2 standard , please visit our website at www.e pa.go v / so2des ignation s. Should you have any questions , please do not he s itate to call me or Scott Mathias of m y sta ff at 919-541-5310 and mathias.scott@epa.gov. Sincere l y, Janet G. McCabe Acting Assistan t Adminis trator E nclosure cc: Shaun McGrath EPA Re g ion 8 Adm ini stratorENCLOSURE


### TIMELINE FO R 2010 PRIMARY S02 NAAQS DESIGNATIO N 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 recommendation s No later than September 18 , 2015 and supporting information for area designations to the EPA The EPA notifies state s concerning any 

### ola J a nuary 22 , 2016 , but abso lutely no later intended modifi cation s to their than 120 days prior to final designations , 

### i.e. , r eco mmendation s ( 1 20- d ay letters) March 2, 2016 The EPA publishes pub li c notice 

### Of state o/a February 3 , 2 016 r eco mmendation s and the EPA 's intended modifications and ini tiates 30 -day public comment period End of 30-day pub l ic comment period o /a March 4 , 2016 States provide additiona l information to o/a Apri l 8 , 2016 demonstrate why an EPA modification is inappropria te The EPA promulgates final S02 area No later than Ju ly 2 , 2016 designations (no later than 16 months from Court Order)

0 0 

### *The court's order d irect s the EPA to promulgate add itiO nal round s of desi g nations b y D ecember 3 1 , 2017 , and by December 31 , 20 20. 

## * * o/a 

### = on or about