UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGIONS Tegan Treadaway

, Director Air Permits Division

1445 ROSS AVENUE

, SUITE 1200 DALLAS TX 75202-2733 October

2 0 , 2 015 Louisiana

D e partment of Environmental Quality P.O. Box 4313 Baton Rouge, LA 7 0821-4313 Dear Ms. Tr e adaway: Thank you for the recommend"tions regarding the attainment status of selected areas in Louisiana under the 2010 sulfur dioxide (S02) rational ambient air quality standard (NAAQS) that your agency se n t to us on September

18
, 2015. As you know, we are subject to a March 2, 2015 court order directing us to promulgate S0 2 designations
for these areas under section 107 of the Clean Air Act by July 2 , 20 1 6. Specifically

, we ar e required
to promulgate designations
for th e se areas because they contain sour
c es meeting the SD2 emissions criteria identified
in the consent decree. The information you provided on Septemb

e r 18
, 2015

, will greatly help us meet this duty

, and en s ure protection of public health in Louisiana. In addition
to th e i nf ormation you have provided

, we have recently rec e ived modeling and related information from

t he Sierra Club that is relevant to a subset of the areas to be addressed by July 2 , 2016. In your state

, we have received information pertinent
to the area near to the following power plan t: Dolet Hills Power Station. We are enclosing

a compact disc that contains this information. Please let us know if you have any questions about the information we have received or if you need any additional information. I am writing to sol
i cit your review of the information that Sierra Club has provided, so that the EPA can base its designation decisions on the best available information. The Clean Air Act provides for designations

to be developed through

a partnership
of state agencies and the EPA; however, we a l so believe

it is impo rt ant to consider significant and relevant information that members of the public provide
to u s . Con

s i s tent with the structure of the Clean Air Act

, we believe that the best first step in addressing

th i s in fo rmation would be for your agenc
y to provide

it s review of this information. Since the Sierra Club 's rec o mmendation differs from your recommendation,

we would welcome your commentary generally on the

i n formation

as well as your detailed review of the elements of Sierra Club

' s anal y sis. T o the exten

t pra c t icable

, we would appreciate quantitative comparisons
of data used in Sierra Club

' s ana

l ysis compare

d to the data used in your analysis

, to help us evaluate the elements of the two analyses. We would apprec ia te your review of Sierra Club's information
by November
17, 2015. Your timely review woul d pro v i de us va l uable assistance
in our review of your designation recommendations
and dev e lopme
n t of our intended designations, which we are aiming to complete by the end of Januar
y 2016. We will then pub li sh notice of our intended designations
for public comment, and, as required by the lntemet Address (URL)

• http :llwww.epa.gov/region6 Recyc

l ed/Recyclable

• Printed with Vegetable Oil Based Inks on 100 % Postconsumer, Process Chlorine Free Recyc

l ed PaperCleanAirAct,promulgatefinaldesignationsnosoonerthan120daysaftergivingyounoticeofthem.Pleasecontactmeor JamesE.Gradyofmystaffat214-665-6745oratgrady.james@epa.govifyouhaveanyquestions aboutthisrequest.Enclosure:1cdSincerely,GuyDonaldsonChiefAirPlanningSection