DAQ-2025-002379

195 North 1950 West • Salt Lake City, UT
Mailing Address: P.O. Box 144820 • Salt Lake City, UT 84114-4820
Telephone [phone] • Fax [phone] • T.D.D. 800 346-3128
www.deq.utah.gov
Printed on 100% recycled paper
State of Utah

Department of
Environmental Quality

Tim Davis
Executive Director

DIVISION OF AIR QUALITY
Bryce C. Bird Director

SPENCER J. COX
Governor

DEIDRE HENDERSON
Lieutenant Governor
DAQP-029-25

May 9, 2025

Cyrus Western
Regional Administrator
U.S. EPA, Region 8
1595 Wynkoop Street
Denver, Colorado 80202-1129

RE: Data Requirements Rule: 2024 SO2 Emissions Annual Report

Dear Mr. Western:

Section 51.1205(b) of the Data Requirements Rule (DRR) for the 2010 1-Hour Sulfur Dioxide
(SO2) Primary National Ambient Air Quality Standard (NAAQS) requires that air agencies submit
to the EPA Regional Administrator a report that documents the annual SO2 emissions of each
applicable source, beginning with the calendar year after the effective date of the area’s initial
designation. Utah has three DRR sources in two counties as shown in the table below.

DRR Source County
Modeling Years
2019 2020 2021
% change from highest
modeling year to 2023 2012 2013 2014 2022 2023 2024
Hunter
Power Plant Emery

4,533

5,055

3,939

3,545.8 2,957.0 3,848.3 3,274.5 1,940.2 1,993.2 -60.6%
Huntington
Power Plant Emery

2,301

2,411

2,479

2,144.1 1,626.3 2,690.3 2,518.8 1,057.1 771.8 -68.9%
Intermountain
Power Plant Millard

3,553

4,727

4,372

2,021.2 2,207.3 2,414.7 1,666.9 848.1 1,643.7 -65.2%

Both counties were designated “attainment/unclassifiable” on January 9, 2018, using the modeling
approach outlined in the DRR based upon actual emissions data from 2012 through 2014 from
each DRR source. For each of the three DRR sources, the table shows the 2012-2014 emissions
data in tons per year used in the Utah Division of Air Quality (UDAQ) modeling analysis as well
as annual emissions data for 2019 through 2024.

DAQP-029-25
Page 2

As can be seen, SO2 emissions for the most recent data year (2024) were lower than the highest
modeling year emissions level for the Hunter, Huntington, and Intermountain power plants.
Specifically, 2024 emissions were lower than 2013 emissions by 60.6% for the Hunter power
plant. In addition, 2024 emissions were lower than 2014 emissions by 68.9% for the Huntington
power plant. Finally, 2024 emissions were lower than 2013 emissions by 65.2% for the
Intermountain power plant.

Under §51.1205(b)(1), air agencies are required to include a recommendation in their annual
report regarding whether additional modeling is needed to characterize air quality in areas with
DRR sources. Because 2024 emissions levels have decreased compared to the modeling years for
the Hunter, Huntington, and Intermountain power plants, UDAQ recommends that no additional
modeling is needed at this time to further characterize air quality in the areas surrounding Utah’s
DRR facilities.

As per §51.1205(b), this assessment will be posted on UDAQ’s website for a period of 30 days
beginning on May 12, 2025, for public inspection. If you have any questions or need additional
information regarding this submission, please contact Tasnuva Islam at 801-536-0076 or
[e-mail].

Sincerely,

Bryce C. Bird
Director