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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 8 1595 Wynkoop Street DENVER, CO 80202-1129 Phone 800-227-8917 http://www,epa,gov/region08

Ref: 8P-AR The Honorable John Hickenlooper Governor ofColorado State Capitol Denver, Colorado 80203
Dear Governor Hickenlooper: OnJune 3, 20I0, the U.S. Environmental Protection Agency (EPA) revised the healthbased National Ambient Air Quality Standard (NAAQS) for sulfur dioxide (S02) by establishing a new I-hour standard at a level of75 parts per billion (ppb). This new I-hour standard will protectpublic health by reducing people's exposure to high short-term (5-minutes to 24-hours) concentrations ofS02. An area meets the new standard when the 3-year average ofthe 99th percentile ofI-hour daily maximum concentrations does not exceed 75 ppb. Within one year ofestablishing a new orrevised standard, each governor must recommend a designation ofattainment, nonattainment orunclassifiable, with appropriate boundaries, for areas within theirjurisdiction. Therefore, we ask that your State provide designation recommendations, including appropriate area boundaries, for all areas by June 3, 2011, with respectto the I-hourS02 NAAQS. Section 107(d)(1) ofthe Clean Air Act (CAA) describes the process EPA follows for designating areas as meeting or no.t meeting a new or revised NAAQS. The CAA requires that we complete designations by no laterthan June 3, 2012. We plan to announce our intended designations no laterthan 120 days priorto promulgating final designations. Following the announcement ofintended designations, states and tribes will have the opportunity to comment on any modifications EPA proposes to their recommendations. The enclosed memorandum provides guidance to state and local air pollutioncontrol agencies and tribes on the timeline andprocess for designating areas underthe revised S02 standard.Establishing areadesignations is a key step in the process ofproviding the health protection intended by the CAA. Should you have questions regarding this matter, please do not hesitate to contact me or your staffmay contact MonicaMorales, ofmy staff, at (303) 312-6936. Sincerely,

James B. Martin Regional Administrator
Enclosure

cc: Martha Rudolph, Executive Director, CDPHE Paul Tourangeau, Director, APCD

2UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 8 1595Wynkoop Street DENVER, CO 80202-1129 Phone 800-227-8917 http://www.epa.gov/region08

Ref: 8P-AR The Honorable Brian Schweitzer Governor ofMontana State Capitol Helena, Montana 59620-0801
Dear Governor Schweitzer: On June 3. 2010, the U.S. Environmental Protection Agency (EPA) revised the heathbased National Ambient Air Quality Standard (NAAQS) for sulfur dioxide (S02) by establishing a new I-hour standard at a level of75 parts per billion (ppb). This new I-hour standard will protect public health by reducing people's exposure to high short-term (5-minutes to 24-hours) concentrations ofS02. An area meets the new standard when the 3-year average ofthe 99th percentile ofI-hour daily maximum concentrations does not exceed 75 ppb. Within one year ofestablishing a new orrevised standard, each governor must recommend a designation ofattainment, nonattainment or unclassifiable, with appropriate boundaries, for areas within theirjurisdiction. Therefore, we ask that your State provide designation recommendations, including appropriate area boundaries, for all areas by June 3, 2011, with respect to the I-hour S02 NAAQS. Section I07(d)(l) ofthe Clean Air Act (CAA) describes the process EPA follows for designating areas as meeting or not meeting a new orrevised NAAQS. The CAArequires that we completedesignations by no later than June 3, 2012. We plan to announce our intended designations no laterthan 120 days priorto promulgating final designations. Following the announcement ofintended designations, states and tribes will have the opportunity to comment on any modifications EPA proposes to their recommendations. The enclosed memorandum provides guidance to state and local air pollution control agencies and tribes on the timeline and process for designating areas underthe revised S02 standard.Establishing area designations is akey step in the process ofproviding the health protection intended by the CAA. Shouldyou have questions regarding this matter, please do not hesitate to contact me or your staffmay contact MonicaMorales, ofmy staff, at (303) 312-6936. Sincerely,

# /!~::!ti7# Regional Administrator
Enclosure

cc: Richard Opper, Director, DEQ Dave Klemp, BureauChief, ARMB

2UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 8 1595Wynkoop Street DENVER, CO 80202-1129 Phone 800-227-8917 http://www

.epa.gov/region08

Ref: 8P-AR The Honorable Jack Dalrymple Governor ofNorth Dakota State Capitol Bismarck, North Dakota 58505
Dear GovernorDalrymple: On June 3, 2010, the U.S. Environmental Protection Agency (EPA) revised the heathbased National Ambient Air Quality Standard (NAAQS) for sulfurdioxide (S02) by establishing a new I-hour standard at a level of75 parts perbillion (ppb). This new I-hour standard will protect public health by reducing people's exposure to high short-term (5-minutesto 24-hours) concentrations ofS02 . An area meets the new standard when the 3-year average ofthe 99th percentile ofI-hourdaily maximum concentrations does not exceed 75 ppb. Within one year ofestablishing a new orrevised standard, each governor must recommend a designation ofattainment, nonattainment orunclassifiable, with appropriate boundaries, for areas within theirjurisdiction. Therefore, we ask that your State provide designation recommendations, including appropriate areaboundaries, for all areas by June 3, 2011, with respect to the I-hour S02 NAAQS. Section I07(d)(1) ofthe Clean Air Act (CAA) describes the process EPA follows for designating areas as meeting ornot meeting a new orrevised NAAQS. The CAA requires that we complete designations by no laterthan June 3, 2012. We plan to announce our intended designations no laterthan 120 days prior to promulgating final desigriations. Following the announcement ofintended designations, states and tribes will have the opportunityto commenton any modifications EPA proposes to their recommendations. The enclosed memorandum provides guidance to state and local air pollution control agencies and tribes onthe timeline and process for designating areas under the.revised S02 standard.Establishing area designations is a key step in the process ofproviding the health protection intended by the CAA. Should youhave questions regarding this matter, please do not hesitate to contact me oryourstaffmay contact MonicaMorales, ofmy staff, at (303) 312-6936. Sincerely,

# 4~' James B. Martin Regional Adminis ratol'
Enclosure

cc: David Glatt, Section Chief, NDDH Terry O'Clair, Director, NDDH

2UNrrED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 8 1595Wynkoop Street DENVER, CO 80202-1129 Phone 800-227-8917 http://www.epa.gov/region08

Ref: 8P-AR· The Honorable Dennis Daugaard Governor ofSouth Dakota State Capitol Pierre, South Dakota 5750I
Dear Governor Daugaard: On June 3,2010, the U.S. Environmental Protection Agency (EPA) revised the heathbased National Ambient Air Quality Standard (NAAQS) for sulfurdioxide (S02) by establishing a new I-hour standard at a level of75 parts per billion (ppb). This new I-hour standard will protectpublic health by reducing people's exposure to high short-term (5-minutes to 24-hours) concentrations ofS02. An area meets the new standard when the 3-year average ofthe 99th percentile ofI-hourdaily maximum concentrations does not exceed 75 ppb. Within oneyear ofestablishing a new orrevised standard, each governor must recommend a designation ofattainment, nonattainment or unclassifiable, with appropriate boundaries, for areas within theirjurisdiction. Therefore, we ask that your State provide designation recommendations, including appropriate area boundaries, for all areas by June 3,2011, with respect to the I-hour S02 NAAQS. Section 107(d)(1) ofthe CleanAir Act (CAA) describes the process EPA follows for designating areas as meeting or not meeting a new orrevised NAAQS. The CAA requires that we complete designations by no later than June 3, 2012. We plan to announce our intended designations no later than 120 days prior to promulgating final designations. Following the announcement ofintended designations, states and tribes will have the opportunity to commentonany modifications EPA proposes to their recommendations. The enclosed memorandum provides guidance to state and local air pollution control agencies and tribes on the timeline and process for designating areas under the revised S02 standard.Establishing areadesignations is a key step in the process ofproviding the health protection intended by the CAA. Should you have questions regarding this matter, please do not hesitate to contact me or your staffmay contact MonicaMorales, ofmy**stafl~** at (303) 312-6936. Sincerely,

# L-t~ James B.

# Mart~ Regional Administrator
Enclosure

cc: Steven M. Pimer, P.E. Secretary, DENR Brian Gustafson, Administrator, AQP



### 2UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 8 1595Wynkoop Street DENVER, CO 80202-1129 Phone 800-227-8917 http://W'NW.epa.gov/region08

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# 24 2011 Ref: 8P-AR The Honorable Gary R. Herbert Governor ofUtah State Capitol Salt Lake City, Utah 84114
Dear Governor Herbert: On June 3, 2010, the U.S. Environmental Protection Agency (EPA) revised the heathbased National Ambient Air Quality Standard (NAAQS) for sulfur dioxide (SOl) by establishing a new I-hour standard at a level of75 parts perbillion (ppb). This new I-hour standard will protect public health by reducing people's exposure to high short-term (5-minutes to 24-hours) concentrations ofSOl. An area meets the new standard when the 3-yearaverage ofthe 99th percentile ofI-hour daily maximum concentrations does not exceed 75 ppb. Within one year ofestablishing a new orrevised standard, each governor must recommend a designation ofattainment, nonattainment orunclassifiable, with appropriate boundaries, for areas within theirjurisdiction. Therefore, we ask that your State provide designation recommendations, including appropriate area boundaries, for all areas by June 3, 2011, with respect to the I-hour SOlNAAQS. Section 107(d)(l) ofthe Clean Air Act (CAA) describes the process EPA follows for designating areas as meeting ornot meeting a new or revised NAAQS. The CAA requires that we complete designations by no laterthan June 3, 2012. We plan to announce our intended designations no later than 120 days prior to promulgating final designations. Following the announcement ofintended designations, states and tribes will have the opportunity to comment on any modifications EPA proposes to their recommendations. The enclosed memorandum provides guidance to state and local air pollution control agencies and tribes on the timeline and process for designating areas under the revised S02 standard.Establishing area designations is a key step in the process ofproviding the health protection intended by the CAA. Should you have questions regarding this matter, please do not hesitate to contact me oryour staffmay contact MonicaMorales, ofmy staff, at (303) 312-6936. Sincerely,

James B. Martin Regional Administ
Enclosure

cc: Amanda Smith, Executive Director, UDEQ Cheryl Heying, Director, DAQ

2UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 8 1595Wynkoop Street DENVER, CO 80202-1129 Phone 800-227-8917 http://www.epa.gov/region08

Ref: 8P-AR The Honorable Matt Mead GovernorofWyoming State Capitol Cheyenne, Wyoming 82002
Dear Governor Mead: On June 3, 2010, the U.S. Environmental Protection Agency (EPA) revised the heathbased National Ambient Air Quality Standard (NAAQS) for sulfur dioxide (S02) by establishing a new I-hour standard at a level of75 parts per billion (ppb). This new I-hour standard will protectpublic health by reducing people's exposureto high short-term (5-minutes to 24-hours) concentrations ofS02. An area meets the new standard when the 3-year average ofthe 99th percentile ofI-hourdaily maximum concentrations does not exceed 75 ppb. Within one year ofestablishing a new orrevised standard, each governor must recommend a designation ofattainment, nonattainment or uncIassifiable, with appropriate boundaries, for areas within theirjurisdiction. Therefore, we ask that your State provide designation recommendations, including appropriate areaboundaries, for all areas by June 3,2011, with respect to the I-hour S02 NAAQS. Section 107(d)(l)ofthe Clean Air Act (CAA) describes the process EPA follows for designating areas as meeting or not meeting a new orrevised NAAQS. The CAA requires that we complete designations by no laterthan June 3, 2012. We plan to announce our intended designations no later than 120 days prior to promulgating final designations. Following the announcement ofintended designations, states and tribes will have the opportunity to comment on any modifications EPA proposes to their recommendations. The enclosed memorandum provides guidance to state and local air pollution control agencies and tribes on the timeline and process for designating areas underthe revised S02 standard.Establishing area designations is a key step in the process ofproviding the health protection intended by the CAA. Should you have questions regarding this matter, please do not hesitate to contact me oryour staffmay contact Monica Morales, ofmy staff, at (303) 312-6936. Sincerely,

# ~.~ James B. Martin Regional Administra or
Enclosure

cc: John Corra, Director, DEQ Steven A. Dietrich, Administrator, AQD

2