UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460

The Honorable Ben H. Grumbles Secretary ofthe Environment Maryland Department of the Environment 1800 Washington Boulevard Baltimore, Maryland 21230
Dear Mr. Grumbles: 

## MAR 202015

OFFICE OF AIR AND RADIATION

I am writing to update you on the status ofthe U.S. Environmental Protection Agency's progress in implementing the primary National Ambient Air Quality Standard (NAAQS) for s ulfur dioxide (S02) set in 2010 at 75 parts per billion (ppb) as a 1-hour average. In July 2013 , the EPA identified areas in 16 states as nonattainment and expressed the intent to address designations for the remainder ofthe country in separate future actions.
On March 2, 2015, the U.S

. District Court for the Northern District of California accepted as an enforceable order an agreement between the EPA and S ierra Club and Natural Resources Defense Counci l to resolve litigation concerning the deadline for completing the designations. The court's order directs the EPA to complete designations 

### in three additional rounds: the first round by July 2, 2016 , the second round by December 3 I , 20 17, and the final round by December 3 I , 2020. The EPA will complete these designations by designating areas as either nonattainment, unclassifiable/attainment, or unclassifiable.
In the first round ofdesignations , the EPA will designate two groups of areas: I ) areas that have newly monitored violations of the 20 I0 S02 standard, and 2) areas that contain any stationary source that according to the EPA ' s Air Markets Database either emitted more than 16,000 tons ofS02 in 2012 or emitted more than 2,600 ton s ofS02 and had an emission rate ofat least 0.45 lbs S02/ mmbtu in 2012 and that has not been announced (as ofMarch 2 , 20 15) for retirement. In the enclosure to this letter, the EPA provides the schedule we intend to follow to meet the July 2, 2016 , deadline.
The EPA has identified the following electric power plant source in your state as meeting the criteria establi shed in the court's order:
2012 S02 2012 

## so2 State County Facility Name Emissions Emissions Rate (tons) (lb/mmbtu) Herbert A Wagner 

### M D Anne Arundel Generating Station 7,514 1.105

Internet Address (URL) • http ://www

.epa.gov Recycled/Recyclable • Printed with Vegetab le Oil Based Inks on 100% Postconsumer, Process Chlorine Free Recycled PaperThe EPA will use the most recent available information when making desi gna tion and boundary decisions for t he indicated area. If you would li ke to submit an updated recommendation and supporting inform at ion for the EPA to consider for the affected area in your state, we request that you do so by September 18, 2015. The EPA has updated its March 24, 20 II , designation guidance for the 2010 S02 standard to support analysis of des i gnations and boundaries for these next rounds of designations. The updated guidance can be found on the EPA's website at http://epa.gov/airquality/sul(urdioxide/guidance.html. The EPA has also provided two technical assistance documents that p r ovide advice on the use of modeling and monitoring data when determining if an area is meeting or not meeting the 20 I 0 S02 standard. These documents can be found on the EPA's website at http :/ /epa .gov /air quali ty/sul(urdioxide ! implement.html. The court's order directs th e EPA to comp l ete the second round of area desi g nations by December 31, 20I7. These designations would address areas where states have not installed and begun operating a new

S02 monitoring network meeting the EPA's specifications referenced in our propo s ed rule titled , "Data Requir eme nts Rule for the I-hour S02 primary NAAQS". This rule , which was proposed in the Federal Register on May I3 , 2014, would direct state and tribal air agencies to provide data to characterize

current air quality in areas with large sources of S02 if such areas do not have sufficient air quality monitoring in place to identify maximum S02 concentrations. T he data collected as a result of this

proposed rule would be used in the designations process. La s tly, the court's order directs the EPA to designate all remaining areas by December 31, 2020. The EPA will provide states with additional information on the designations process associated with these late r deadlines at a later date . We l ook forward to continued dialogue with you and your staff as we work together to implement the

20 I 0 S02 standard and achieve i ts i ntended public health protection. For addit i ona l information regarding designations for the 2010 so2 standard, please visit our website at www . epa . gov/so2designations . Should you have any questions , please do no t hesitate to call me or Scott Math i as ofmy staffat 919-541-5310 and mathias.scott@epa . gov. Sincerely, Janet G. McCabe Acting Assistant Administrator En closure cc : Shawn Garvin EPA Region 3 AdministratorENCLOSURE
TIMELINE FOR 20 10 PRIMARY S02 NAAQS DESIGNATION PROCESS FOR AREAS ASSOCIAT ED WITH JULY 2, 20 16, COURT-ORDERED DEADLINE* Milestone Date** Court Order March 2, 20 15 States may submit updated recommendations No later than September 18 , 2015 and supporting information for area designations to the EPA The EPA notifies states concerning any o/a January 22 , 2016 , but absolutely no later intended modifications to their than 120 days prior to final designations, 

### i.e., recommendations ( 120-day letters) March 2, 2016 The EPA publishes public notice of state o/a February 3, 2016 recommendations and the EPA's intended modifications and initiates 30-day public comment period End of30-day public comment period o/a March 4 , 2016 States provide additional information to o/a April 8 , 201 6 demonstrate why an EPA modification is inappropriate The EPA promulgates final S02 area No later than July 2, 2016 designations (no later than 16 months from Court Order)

.. *The court's order directs the EPA to promulgate additional rounds ofdes1gnat10ns by December 31 , 2017 , and by December 31 , 2020.
** o/a 

### = on or about