Mr. Ron Curry, R egional Administrator 

## Mary Fallin Governor August 17 , 2015

U. S. Env iro nmental Protectio n Agency, Reg i on 6 1445 Ros s Avenue, Suite 1 20 0 Dallas , Texas 752 02 -2733 i

. • - ..**~** - , 

## · ._ , -UL 

# AlR l·i.'.
· 1 ·1 :: : \1 SEC. 

## 15 AUG 26 PM S : 2 4

Subject: A ffirmation of D es ignation Recomm e ndation for 20 l 0 Sulfur D i ox ide NAA QS fo r Nob le , C h octaw, and Mu skogee Countie s in Oklahoma Dear Administrator Curry: Oklahoma has evaluated th e letter from A c ting Assis tant Admin i strator Mc Cabe dated March 2 0 , 2015, which gave an up da te o n the U.S. E n viro nmental Prote c ti on Agency ' s (EPA ' s) status o n implement ing the revise d primary National Ambient Air Quality Standard (NAA QS) for sulfur dioxid e (S0 2) (75 FR 35520, June 22, 2010)
. Accompanying the letter wa s the "Upda te d Guidance for Area Designations for the '20 10 Primary Sulfur Dioxide National Ambient Air Quality Stand ar d. '" In the le tt e r , EPA outlined three future rounds of des igna tion actions to comply wi th t he fe de ral consen t decree and cou rt order i ssued in Sierra Club, et al v . Re gi na McCart hy, Ca s e No. 3: l 3-cv-03 953-SI (N.D. Cal.), and id e ntified areas in Noble, Choctaw, and Musko gee Counties as aff ected by the first round of desi g n ations
. Each of these areas contain s a source that me e ts the crit e r ia estab lish ed in the federal conse nt decree for inclusion in the first round of designation act ions . The lett er prov ided an opportunity to s ubmit an upd ated re c omm e n dati o n and suppo rti ng info rm ation for E P A c on s id e ration fo r d es ignation o f the affected areas. As re quired b y sec tion 107(d)(l)(A) of the federa l Clean A i r Act (42 U.S. C. 

### § 7407) and o n beha lf of the Sta te o f Okl ahoma , I rec o mm e nded on May 27, 20 11 , Noble and C hoctaw Counties be des i g n ated a tta inment , and Muskogee Co unt y be de s ig n ated unclassifiable fo r the re vised S0 2 standard. Ou r rec ommen datio n for these thr ee co unties /area s remains unchan ged. Under se p arat e cover , Ok lahoma i s s ubmittin g an air qu ality evaluation, performed by th e Oklahom a Department of Environmental Quality (DEQ), to support our curren t recommendati o n. DEQ 's re port evaluates certified S0 2 m onitoring data , a nd m o deling fo r contributing S02 sources in the three identified areas. Specifically, the evaluation demon stra t es

ST.-JT E CA P ITO L BUILDl. VG • 2 300 N. ll.\'COL.\' BOULEVARD
. SUITE 212 •**OKLAHO H~**  CITY
. OKLAHOA4A 73105 • 1405) 521

- 2342 • FAX : 1405) 511 -3353atta inm e nt for the areas associated with the two facili ti es in Noble and Choc t aw Counties. T he air quality ana l ysis fo r Muskogee Co un ty shows no violation of the 20 10 S0 2 NAA QS has bee n detected at the source - oriented S02 monitoring s ite located approximate ly 4 kilometers NNW of th e facility for the last three ye ars o f availabl e ce rti fie d data. However, modeling for the facility in d icat es ther e may b e a potential for a N AAQS v iol ati o n und er certain co nditions during t he period pr io r t o full implementation of the facility's fede ra lly

- enforceable BART requ irements and other planned changes (e.g. , i n re s p o n se to Me rcury and Ai r Toxics Standards). The eva lu at io n identified significant uncertaintie s regarding the e ffe c t s of availab le meteorologi c al data on the mode lin g re s ults. (Modeling did not show any potential violations at recepto rs located outsi de Muskog ee County.) We b e li eve this information co ll ec tiv e ly supports a de s ignat ion of unclass ifiable for Muskogee County. If yo u desire addi ti o n al informat ion o r have questions concerning thi s matter , please contact Mr. Eddie Te rrill , DEQ's Dire cto r of A ir Qualit y , at (405) 7 02-4100. Sincerely,
Mary Fallin , G State of Oklahoma

cc : Micha el Teague , Sec retary o f E n ergy and E nvironme nt Scott Thompso n , Exec utive Dir ector, D e partm e nt of E nvironme nt al Quality E ddie T errill , Dir ec tor of Air Quality , Depa rtment of Environment a l Quality