MATTHEW H. MEAD STATE CAPITOL 

GOVERNOR OF WYOMING CHEYENNE, WY 82002

o ce or t e Governor 

May 24, 2011 

James B. Martin,- Regional Administrator 

EPA Region 8 

Mail Code: AP-AR 

1595 Wynkoop Street 

Denver, CO 80202-1129 

Re: I-Hour Primary National Ambient Air Quality Standard (NAAQS) for Sulfur 

Dioxide (S02) 

Dear Mr. Martin: 

The State of Wyoming is making recommendations regarding designations of the I-hour 

primary National Ambient Air Quality Standard (NAAQS) for sulfur dioxide (S02) that 

became effective on June 22, 2010. 

The Department of Environmental Quality (DEQ) reviewed the most recent three years of 

S02 monitoring data available to make designation recommendations. The results and 

supporting data are found in Attachment 1 to this letter. Based on a review of the monitoring 

data, the DEQ would recommend "attainment" for all counties in the State. However, the 

DEQ has also reviewed the March 24, 2011 Steven A. Page memo, "Area Designations for 

the 2010 Revised Primary Sulfur Dioxide National Ambient Air Quality Standards," which 

sets forth a different approach to making designations relying heavily on modeling rather 

than monitoring. The guidance recommends a temporary unclassifiable status for most areas 

of the country due to a lack of modeling. Based on this guidance, the State is left with no 

option but to designate all counties of the State, as indicated in the table below, as 

"unclassifiable" for the current I-hour primary standard for sulfur dioxide. 

Regions I-Hour Primary 802 

NAAQ8 Desienation 

Albany County Unclassifiable 

Big Horn County Unclassifiable 

Campbell County Unclassifiable 

Carbon County Unclassifiable 

Converse County Unclassifiable 

......:..... 

HO E FAX: (307) 632-3909 (307) 777-7434 
,VIr. Jarn~s H. ,1ill'llll 

MilY 2,1. 20 I I 

Page '2 

Crook County Unclassifiable 

Fremont County Unclassifiable 

Goshen County Unclassifiable 

Hot Springs COlmty Unclassifiable 

Johnson County Unclassifiable 

Laramie COWlty Unclassifiable 

Lincoln County Unclassifiable 

Natrona County Unclassifiable 

Niobrara COtmty Unclassifiable 

Park County Unclassifiable 

Platte County Unclassifiable 

Sheridan County Unclassifiable 

Sublette Cotmty Unclassifiable 

Sweetwater County Unclassifiable 

Teton COtmty Unclassifiable 

Uinta County Unclassifiable 

Washakie COtmty Unclassifiable 

Weston County Unclassifiable 

There are portions of the above mentioned cotmties which are under the jurisdiction of Tribal 

Authorities. It is my tmderstanding that Tribal designations will be made separate from State 

designations. 

I am not convinced that the hybrid approach described in the guidance, which gives modeling 

considerably more weight than monitoring, is the correct method to apply. I questions whether 

the hybrid approach promoted by EPA is based on sotmd science, since I have not been provided 

with a solid demonstration showing the accuracy of the model in predicting monitored 

conditions. I also question why EPA would want to undermine the validity of monitored data, 

which most states depend on for growld-truthing their air programs. It is my belief that there 

needs to be more discussion with states on how to designate areas for the new I-hour S02 

standard. Wyoming looks forward to participating in such a discussion. 

, I hope that the EPA will reconsider the hybrid approach in addressing designations. If you have 

questions concerning the details of this recommendation, please feel free to contact Steven A. 

Dietrich, Administrator, Department of Environmental Quality, Air Quality Division, at 307­

777-7391. 

Bestregards, 
Mr. .fame:, B. MHl'lir, 

['v1n:.' 2<;, 20 I I 

Pall.e ~\

Cc:	 John V. Corra, Director, DEQ 

Steven A. Dietrich, Administrator, Air Quality Division, DEQ 

Christine Anderson, Air Quality Division, DEQ 

Cara Keslar, Air Quality Division, DEQ 

Chad Schlichtemeier, Air Quality Division, DEQ 
f\.lr Jam~s B. l\lartlll 

May ~4. ~Oll

Page -+ 

ATTACHMENT 1: S02 Monitored Data in Wyoming 

2007-2009 

The I-hour primary S02 NAAQS is met when the three-year average ofthe 99th percentile daily 

maximum I-hour concentration, as determined in accordance with 40 CFR part 50 Appendix T, 

Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Sulfur 

(Sulfur Dioxide), is the 3-year average of the annual 99th percentile daily maximum I-hour 

values for a monitoring site. The following table presents data collected from 2007-2009 that 

have met the data collection requirements presented in Appendix T. 

Monitor Narne AQD Site ID I 

3-Year 99th Percentile 

Average (ppb) 

Black Hills 56-005-0857 63 

4 

24 

4 

5 

Murphy Ridge 56-041-0101 

Newcastle Refinery 56-045-0800 

South Pass 56-013-0099 

Wamsutter 56-037-0200 

I 

I 

State of Wyoming Map Showing Monitor Locations Considered in this Analysis 

1 Hour Primary 502 MonUors • Cb!~

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