UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION

7 The Honorable Terry Branstad Governor, State of Iowa 1 007 East Grand State Capitol Building Des Moines, Iowa 50319 Dear Governor Branstad:

11201 Renner Boulevard Lenexa, Kansas 66219 

## FEB 1 6 2016

OFFICE OF THE REGIONAL ADMINISTRATOR Thank you for your recommendations dated November

4 , 2015, on air quality designations
for the state oflowa for the 2010 revision to the primary National Ambient Air Quality Standard for sulfur dioxide. Reducing levels of sulfur dioxide pollution

is an important part of the U.S. Environmental Protection Agency's commitment

to a clean, healthy environment. Exposure

to sulfur dioxide can cause

a range of adverse health effects, including narrowing of the airways which can cause difficulty breathing and increased asthma symptoms. This letter is to notify you of our preliminary intentions regarding your staff's recommended designations. On June 3, 2010, the EPA strengthened the health-based

or primary standard for sulfur dioxide by establishing

a standard for one-hour average sulfur dioxide concentrations

at a level of75 parts per billion. Within one year after
a new or revised standard

is established

, the Clean Air Act requires the governor of each state to submit to the EPA
a list of all areas in the state, with recommendations

for whether each area meets the standard. Through an interactive process, the EPA consider

s the recommendations
and then promulgates designations
for all area
s acros

s the country. On July 25
, 2013

, the EPA designated
29 areas in 16 states as nonattainment,
but did not at that time designate other areas. Pursuant
to a March
2, 2015, court-ordered schedule,

1 the EPA must complete the remaining sulfur dioxide designations
by three specific deadlines: July 2, 2016, December 31, 201 7 , and December 31, 2020. This current round of designations,

to be completed by July 2, 2016, addresses two groups of areas: (1) areas that have newly monitored violations of the 2010 sulfur dioxide standard based on the most recent three calendar years of certified monitored ambient air quality data, and (2) areas that contain any stationary source that had not been announced

as of March 2, 2015, for retirement and that according

to the EPA's Air Markets Database emitted in 2012 either (i) more than 16,000 tons of sulfur dioxide or (ii) more than 2,600 tons of sulfur dioxide with an annual average emission rate of at least 0.45 pounds of sulfur dioxide per one million British Thermal Units. 1 Sierra Club v. McCarthy, No. 3-13-cv-3953 (SI) (N.D. Cal. Mar. 2, 2015)

. ®Printed

on Recycled PaperBecause,

at this time, the EPA does not have conclusive infonnation

to detennine whether the following areasare meeting ornot meeting the sulfur dioxide standard, the EPA intends to designate these areasas unclassifiable: Intended Unclassifiable Area Des Moines County* Wapello County* Woodbury County* Intended Unclassifiable Counties Des Moines County Wapello County Woodbury County The asterisk (*) indicates the designation for this intended unclassifiable area represents

amodification to the designation that youhave recommended. The enclosed technical support document provides

adetailed analysis that supports ourintended designation decisions.
If yourstate has additional information that weshould consider prior to finalizing these designations, please submit
it to us by April19, 2016. We also will be publishing

anotice in the Federal Register announcing

a 30-day period for the public to provide input onourintended designation decisions. We will promulgate the designations
for these areas by July 2, 2016. We will designate all other previously undesignated areasin the state onaschedule consistent with the prescribed timing of the court order, i.e., by December 31, 2017, orDecember 31, 2020. We look forward
to acontinued dialogue with youand yourstaff aswework together
to complete the area designations and implement the 2010 primary sulfur dioxide standard. For additional information regarding designations under the sulfur dioxide standard, please visit ourwebsite
at www.epa.gov/sulfur dioxidedesignations. Should youhave any questions, please do not hesitate
to call me,orhave yourstaff contact David Peter of mystaff at (913) 551-7397
or peter.david@epa.gov. Sincerely, Mark Hague Enclosure cc:Chuck Gipp, Iowa Department ofNatural Resources Catherine Fitzsimmons, Iowa Department ofNatural Resources Janet G. McCabe, USEPA Headquarters Stephen D. Page, Research Triangle Park