Document ID: EPA-R07-OAR-2021-0932-0001
Agency: epa
Document Type: Proposed Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Iowa; Determination of Attainment by the Attainment Date for the 2010 1-Hour Sulfur Dioxide Standard
Posted Date: 2022-01-26T05:00Z

[Federal Register Volume 87, Number 17 (Wednesday, January 26, 2022)]
[Proposed Rules]
[Pages 3958-3963]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-01497]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R07-OAR-2021-0932; FRL-9461-01-R7]

Air Plan Approval; Iowa; Determination of Attainment by the 
Attainment Date for the 2010 1-Hour Sulfur Dioxide Standard

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
determine that the Muscatine sulfur dioxide (SO2) 
nonattainment area attained the 2010 1-

[[Page 3959]]

hour SO2 primary national ambient air quality standard 
(NAAQS) by the applicable attainment date of October 4, 2018, based 
upon a weight-of-evidence analysis using available air quality 
information. Additional analysis of the attainment determination is 
provided in a Technical Support Document (TSD) included in the docket 
to this proposed rulemaking. This action, if finalized, will address 
the EPA's obligation under a consent decree which establishes a 
deadline of March 31, 2022 for the EPA to determine under Clean Air Act 
(CAA) section 179(c) whether the Muscatine SO2 nonattainment 
area attained the NAAQS by the October 4, 2018 attainment date.

DATES: Comments must be received on or before February 25, 2022.

ADDRESSES: You may send comments, identified by Docket ID No. EPA-R07-
OAR-2021-0932 to https://www.regulations.gov. Follow the online 
instructions for submitting comments.
    Instructions: All submissions received must include the Docket ID 
No. for this rulemaking. Comments received will be posted without 
change to https://www.regulations.gov, including any personal 
information provided. For detailed instructions on sending comments and 
additional information on the rulemaking process, see the ``Written 
Comments'' heading of the SUPPLEMENTARY INFORMATION section of this 
document.

FOR FURTHER INFORMATION CONTACT: Jason Heitman, Environmental 
Protection Agency, Region 7 Office, Air Quality Planning Branch, 11201 
Renner Boulevard, Lenexa, Kansas 66219; telephone number: (913) 551-
7664; email address: [email protected].

SUPPLEMENTARY INFORMATION: Throughout this document ``we,'' ``us,'' and 
``our'' refer to the EPA.

Table of Contents

I. Written Comments
II. Background
    A. The 2010 SO2 National Ambient Air Quality 
Standards
    B. Designations, Classifications, and Attainment Dates for the 
2010 SO2 National Ambient Air Quality Standard
III. Proposed Determination
    A. Applicable Statutory and Regulatory Provisions
    B. Monitoring Network Considerations
    C. Data Considerations and Proposed Determination
    i. Emissions Information
    ii. Monitoring Data
    iii. Meteorology
    iv. Modeling Information
    v. Conclusion
IV. Proposed Action and Request for Public Comment
V. Environmental Justice Concerns
VI. Statutory and Executive Order Reviews

I. Written Comments

    Submit your comments, identified by Docket ID No. EPA-R07-OAR-2021-
0932, at https://www.regulations.gov. Once submitted, comments cannot 
be edited or removed from Regulations.gov. The EPA may publish any 
comment received to its public docket. Do not submit electronically any 
information you consider to be Confidential Business Information (CBI) 
or other information whose disclosure is restricted by statute. 
Multimedia submissions (audio, video, etc.) must be accompanied by a 
written comment. The written comment is considered the official comment 
and should include discussion of all points you wish to make. The EPA 
will generally not consider comments or comment contents located 
outside of the primary submission (i.e., on the web, cloud, or other 
file sharing system). For additional submission methods, the full EPA 
public comment policy, information about CBI or multimedia submissions, 
and general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.

II. Background

A. The 2010 SO2 National Ambient Air Quality Standards

    Under section 109 of the CAA, the EPA has established primary and 
secondary NAAQS for certain pervasive air pollutants (referred to as 
``criteria pollutants'') and conducts periodic reviews of the NAAQS to 
determine whether they should be revised or whether new NAAQS should be 
established. The primary NAAQS represent ambient air quality standards 
the attainment and maintenance of which the EPA has determined, 
including a margin of safety, are requisite to protect the public 
health. The secondary NAAQS represent ambient air quality standards the 
attainment and maintenance of which the EPA has determined are 
requisite to protect the public welfare from any known or anticipated 
adverse effects associated with the presence of such air pollutant in 
the ambient air.
    Under the CAA, the EPA must establish a NAAQS for SO2. 
SO2 is primarily released to the atmosphere through the 
burning of fossil fuels by power plants and other industrial 
facilities. SO2 is also emitted from industrial processes 
including metal extraction from ore and heavy equipment that burn fuel 
with a high sulfur content. Short-term exposure to SO2 can 
damage the human respiratory system and increase breathing 
difficulties. Small children and people with respiratory conditions, 
such as asthma, are more sensitive to the effects of SO2. 
Sulfur oxides at high concentrations can also react with compounds to 
form small particulates that can penetrate deeply into the lungs and 
cause health problems.
    The EPA first established primary SO2 standards in 1971 
at 0.14 parts per million (ppm) over a 24-hour averaging period and 0.3 
ppm over an annual averaging period (36 FR 8186, April 30, 1971). In 
June 2010, the EPA revised the NAAQS for SO2 to provide 
increased protection of public health, providing for revocation of the 
1971 primary annual and 24-hour SO2 standards for most areas 
of the country following area designations under the new NAAQS. The 
2010 NAAQS is 75 parts per billion (ppb) (equivalent to 0.075 ppm) over 
a 1-hour averaging period (75 FR 35520, June 22, 2010). A violation of 
the 2010 1-hour SO2 NAAQS occurs when the annual 99th 
percentile of ambient daily maximum 1-hour average SO2 
concentrations, averaged over a 3-year period, exceeds 75 ppb.

B. Designations, Classifications, and Attainment Dates for the 2010 SO2 
National Ambient Air Quality Standards

    Following promulgation of any new or revised NAAQS, the EPA is 
required by CAA section 107(d) to designate areas throughout the nation 
as attaining or not attaining the NAAQS.
    On August 5, 2013, the EPA finalized its first round of 
designations for the 2010 primary 1-hour SO2 NAAQS (78 FR 
47191). In the 2013 action, the EPA designated 29 areas in 16 states as 
nonattainment for the 2010 SO2 NAAQS, including a portion of 
Muscatine County in Iowa. The designation was based on air quality 
monitoring data from 2009-2011 showing violations of the NAAQS. The 
EPA's initial round of designations for the 2010 SO2 NAAQS 
including the Muscatine nonattainment area (NAA) became effective on 
October 4, 2013. Pursuant to CAA sections 172(a)(2) and 192(a), the 
maximum attainment date for the Muscatine NAA is October 4, 2018, five 
years after the effective date of the final action designating the area 
as nonattainment for the 2010 SO2 NAAQS.

[[Page 3960]]

III. Proposed Determination

A. Applicable Statutory and Regulatory Provisions

    Section 179(c)(1) of the CAA requires the EPA to determine whether 
a nonattainment area attained an applicable standard by the applicable 
attainment date based on the area's air quality as of the attainment 
date.
    A determination of whether an area's air quality meets applicable 
standards is generally based upon the most recent three years of 
complete, quality-assured data gathered at established state and local 
air monitoring stations (SLAMS) in a nonattainment area and entered 
into the EPA's Air Quality System (AQS) database. Data from ambient air 
monitors operated by state and local agencies in compliance with the 
EPA monitoring requirements must be submitted to AQS. Monitoring 
agencies annually certify that these data are accurate to the best of 
their knowledge. All data are reviewed to determine the area's air 
quality status in accordance with 40 CFR part 50, appendix T (for 
SO2). In general, for SO2 EPA does not rely 
exclusively on monitoring data to determine whether the NAAQS is met 
unless it has been demonstrated that the monitors were appropriately 
sited to record expected maximum ambient concentrations of 
SO2 in an area.
    Under EPA regulations in 40 CFR 50.17 and in accordance with 40 CFR 
part 50, appendix T, the 2010 1-hour annual SO2 standard is 
met at an ambient air quality monitoring site when the design value is 
less than or equal to 75 ppb. Design values are calculated by computing 
the three-year average of the annual 99th percentile daily maximum 1-
hour average concentrations. When calculating 1-hour primary standard 
design values, the calculated design values are rounded to the nearest 
whole number or 1 ppb by convention. An SO2 1-hour primary 
standard design value is valid if it encompasses three consecutive 
calendar years of complete data. A year is considered complete when all 
four quarters are complete, and a quarter is complete when at least 75 
percent of the sampling days are complete. A sampling day is considered 
complete if 75 percent of the hourly concentration values are reported; 
this includes data affected by exceptional events that have been 
approved for exclusion by the Administrator.

B. Monitoring Network Considerations

    Section 110(a)(2)(B)(i) of the CAA requires states to establish and 
operate air monitoring networks to compile data on ambient air quality 
for all criteria pollutants. The EPA's monitoring requirements are 
specified by regulation in 40 CFR part 58. These requirements are 
applicable to state, and where delegated, local air monitoring agencies 
that operate criteria pollutant monitors.
    In section 4.4 of appendix D to 40 CFR part 58, the EPA specifies 
minimum monitoring requirements for SO2 to operate at SLAMS. 
SLAMS produce data that are eligible for comparison with the NAAQS, and 
therefore, the monitor must be an approved Federal reference method 
(FRM) or Federal equivalent method (FEM) monitor.
    The minimum number of required SO2 SLAMS is described in 
sections 4.4.2 and 4.4.3 of appendix D to 40 CFR part 58. According to 
section 4.4.2, the minimum number of required SO2 monitoring 
sites is determined by the population weighted emissions index for each 
state's core based statistical area. Section 4.4.3 describes additional 
monitors that may be required by an EPA regional administrator.
    Under 40 CFR 58.10, states are required to submit annual monitoring 
network plans (AMNP) for ambient air monitoring networks for approval 
by the EPA. Within the Muscatine NAA, the State is responsible for 
assuring that each monitoring site meets air quality monitoring 
requirements. Iowa submits an AMNP to the EPA that describes the 
various monitoring sites operated by the State. Each AMNP discusses the 
status of the air monitoring network as required under 40 CFR 58.10 and 
addresses the operation and maintenance of the air monitoring network 
in the previous year. The EPA regularly reviews these AMNPs for 
compliance with the applicable reporting requirements in 40 CFR part 
58. With the EPA's approval of Iowa's most recent AMNP, the State has 
met the applicable minimum monitoring requirements.\1\
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    \1\ EPA's letter approving Iowa's 2021 monitoring network plan 
dated December 2, 2021 is included in the docket for this action.
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    The EPA also conducts regular ``technical systems audits'' (TSAs) 
during which we review and inspect ambient air monitoring programs to 
assess compliance with applicable regulations concerning the 
collection, analysis, validation, and reporting of ambient air quality 
data.
    During the 2015-2017 data period, Iowa operated three 
SO2 SLAMS in the Muscatine SO2 NAA: Greenwood 
Cemetery (AQS ID 19-139-0016); High School East Campus (AQS ID 19-139-
0019); and Musser Park (AQS ID 19-139-0020).

C. Data Considerations and Proposed Determination

    CAA section 179(c)(1) requires the Agency to ``determine, based on 
the area's air quality as of the attainment date, whether the area 
attained the standard by that date.'' The EPA first assessed what air 
quality information was available related to making a determination of 
attainment by the attainment date for the Muscatine area. The EPA chose 
to employ a weight-of-evidence approach for making this determination 
because the EPA does not have any analysis (including modeling) 
associated with the monitor siting to demonstrate that the monitors 
record maximum ambient SO2 concentrations in the NAA, nor 
does EPA have modeling of actual emissions to support a determination 
based on modeled ambient concentrations whether the area attained the 
NAAQS by the attainment date. The available modeling of permitted 
allowable emissions in the area, as discussed later in this document, 
does not on its own provide a basis for determining whether the area 
attained by the attainment date. Thus, EPA relied upon SO2 
emissions data and trends, relevant air monitoring data and trends, 
SO2 monitoring data incorporated with local meteorological 
data, as well as available modeling information in order to make its 
determination under CAA section 179(c)(1). The EPA believes our 
analysis of multiple types of air-quality related information to 
support our determination is consistent with section 179(c)(1)'s 
direction to determine the area's air quality as of the attainment 
date. Further detail on EPA's weight-of-evidence analysis is contained 
in the technical support document (TSD) included in the docket for this 
action.
i. Emissions Information
    There are four facilities that emit or have historically emitted 
SO2 located in or near the Muscatine NAA. Three are located 
within the nonattainment area--Grain Processing Corporation (GPC), 
Muscatine Power and Water (MPW), and Monsanto. Louisa Generating 
Station (LGS) is located south of the nonattainment area. Table 1 
provides the annual emissions from 2011-2020 from each individual 
source along with the total combined emissions among the four 
facilities. In the 2011-2015 timeframe, GPC was the largest 
SO2 source in the Muscatine area, with the majority of 
SO2 emissions attributed to GPC's boilers using coal. A fuel 
switch at GPC's coal-fired boilers to natural gas occurred on July 14, 
2015, and this change led to large reductions of SO2

[[Page 3961]]

emissions at GPC. Prior to 2018, Monsanto was fueled primarily by coal, 
with SO2 emissions associated with its main boiler. As 
required by a construction permit, Monsanto converted its coal-fired 
boiler to use only natural gas in 2018 which eliminated nearly all 
SO2 emissions from Monsanto.
    The EPA first evaluated annual SO2 emissions trends 
within the Muscatine nonattainment area. By 2017, total annual 
emissions in the Muscatine area had dropped approximately 72% from 2014 
(24,181 tons per year (tpy) in 2014 to 6,781 tpy in 2017). Much of the 
reduction in emissions can be attributed to GPC's fuel conversion to 
natural gas in July of 2015, evident by the more than 50% reduction in 
annual SO2 emissions at GPC from 2014 (13,075 tpy) to 2015 
(6,191 tpy) and further reductions to below 200 tpy in 2016 and 2017. 
Overall, GPC's annual SO2 emissions were reduced by 98.7% 
from 2014 to 2017.
    In addition to emissions decreases within the nonattainment area, 
the EPA also looked at emissions at LGS, the nearby source located 
outside the nonattainment area. In the Louisa County Data Requirements 
Rule (DRR) modeling,\2\ Iowa modeled LGS using its permitted allowable 
rate of 4,270.89 lbs/hour,\3\ which would correspond to an annual total 
of 18,706 tpy. Actual annual emissions at LGS during the 2015-2017 
timeframe ranged between 5,129 tpy and 6,098 tpy, significantly below 
the annual total of 18,706 tpy that corresponded with modeled 
attainment. In addition, the actual maximum hourly emission rate at LGS 
since 2011, as reported to EPA Clean Air Markets Division (CAMD) 
database \4\ is 4,014.7 lb/hr, which is also below the 1-hour modeled 
emission rate.
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    \2\ EPA relied on the DRR modeling submitted by Iowa to 
designate Louisa County, containing LGS, as attainment/
unclassifiable for the 2010 1-hour SO2 NAAQS in December 
2017 (83 FR 1098).
    \3\ The 1-hour SO2 modeling rate used for LGS was 
developed from the current 30-day rolling permit limit and actual 
emissions following the approach outlined in the EPA's 2014 Guidance 
for 1-Hour SO2 Nonattainment Area State Implementation Plans.
    \4\ https://ampd.epa.gov/ampd/.

    Table 1--SO2 Emissions (tons) From 2011 to 2019 for Sources Within and Nearby the Muscatine Nonattainment Area. Emissions Are From EPA's National
                                                                Emissions Inventory (NEI)
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                   Source                        2011        2012        2013        2014        2015        2016        2017        2018        2019
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GPC.........................................      11,970      11,640      12,761      13,075       6,191         187         173          84          89
MPW.........................................       2,374       2,015       2,169       1,821       1,714       1,769       1,167       1,458       1,715
Monsanto....................................         537         543         469         502         402         349         208          ~0          ~0
    Louisa..................................       7,306       8,743       8,285       8,783       6,098       5,129       5,233       7,332       5,286
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        Total...............................      22,187      22,941      23,684      24,181      14,405       7,434       6,781       8,874       7,090
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    EPA's evaluation of emissions at sources within and outside of the 
nonattainment area indicate significant reductions in emissions in the 
2015-2017 timeframe compared to pre-2015 emissions.
ii. Monitoring Data
    Under 40 CFR 58.15, monitoring agencies must certify, on an annual 
basis, data collected by FRM or FEMs at all SLAMS, including special 
purpose monitors, that meet EPA quality assurance requirements. In 
doing so, monitoring agencies must certify that the previous year of 
ambient concentration and quality assurance data are completely 
submitted to AQS and that the ambient concentration data are accurate 
to the best of their knowledge. Iowa annually certifies that the data 
it submits to AQS are quality assured, including data collected at 
monitoring sites in the Muscatine SO2 NAA.
    For the Muscatine SO2 NAA the applicable attainment date 
is October 4, 2018. In accordance with appendix T to 40 CFR part 50, 
where determinations of SO2 NAAQS compliance may be made 
based on well-sited air quality monitors, compliance with the NAAQS is 
based on three consecutive calendar years of data. The three calendar 
year period preceding the attainment date for the Muscatine 
SO2 NAA is January 1, 2015-December 31, 2017.
    The 3-year design values of 1-hour SO2 from 2011 through 
2020 for the three Muscatine area monitors are provided in Table 2 and 
the annual 99th percentile of 1-hour SO2 concentrations are 
shown in Table 3. All monitor violations occur before the 2015-2017 
timeframe, with all three monitors showing violations from 2011-2016. 
No monitor violation of the 3-year design value has occurred since 
2016, with the largest of the three 2015-2017 1-hour SO2 
design values of 65 ppb at the Musser Park site. The trends indicated 
in the monitored design values are consistent with EPA's evaluation of 
the emissions trends discussed above. As emission reductions were 
implemented at the sources in the nonattainment area, SO2 
concentrations recorded at the area's air quality monitors decreased. 
Specifically, coal combustion at GPC ceased in mid-2015 and coal 
combustion at Monsanto ceased in late 2017. Significant decreases in 1-
hour daily maximum SO2 concentrations at the air quality 
monitors are consistent with that timeline. While the most recent 
complete and quality-assured design values (2018-2020) for the 
Greenwood Cemetery, High School East Campus, and Musser Park sites (15, 
18, and 20 ppb, respectively) were recorded after the area's attainment 
date, they indicate the effectiveness of the area's control measures. 
These design values are no greater than 27% of the level of the 2010 1-
hour SO2 NAAQS.

                              Table 2--Design Values (ppb) for the 2010 1-Hour SO2 NAAQS for the Muscatine Monitoring Sites
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                        Site name                          2011-2013   2012-2014   2013-2015   2014-2016   2015-2017   2016-2018   2017-2019   2018-2020
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Greenwood Cemetery (19-139-0016)........................  ..........         101          97          77          45          20          17          15
High School E Campus (19-139-0019)......................  ..........  ..........         128          84          42          22          21          18

[[Page 3962]]

 
Musser Park (19-139-0020)...............................         217         194         158         113          65          34          25          20
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                       Table 3--Annual 99th Percentile of 1-Hour Daily Maximum SO2 Concentrations (ppb) Muscatine Monitoring Sites
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                        Site name                            2013        2014        2015        2016        2017        2018        2019        2020
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Greenwood Cemetery (19-139-0016)........................          84         117          91          24          20          15          16          14
High School E Campus (19-139-0019)......................         147         161          75          30          20          16          25          13
Musser Park (19-139-0020)...............................         179         179         116          45          35          24          16          20
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iii. Meteorology
    The EPA does not have conclusive evidence to support that the 
monitors are sited in the area of maximum ambient SO2 
concentrations. EPA would typically rely on the siting analysis 
performed to originally site the monitors or modeling of actual 
emissions to demonstrate the monitors are sited in the area of maximum 
concentrations. There is not a specific analysis associated with the 
siting of the monitors nor does EPA have access to modeling of actual 
emissions for sources in or near the nonattainment area to make such a 
determination. In the absence of that information, EPA has also 
evaluated local meteorology along with the monitored SO2 
values to evaluate the likelihood of maximum ambient concentrations 
occurring in locations that the monitors could not record. Hourly wind 
speeds and direction were collected from the Muscatine Airport, which 
is located approximately 8 kilometers southwest of GPC and the Musser 
Park and High School SO2 monitors. The hourly winds were 
combined into a dataset with the coinciding one hour monitored 
SO2 concentrations and plotted using SO2 
pollution roses. This analysis provides information to help determine 
from where (and potentially what source) the monitored impacts were 
coming. In summary, the monitors appear to be positioned in downwind 
areas of relatively high impacts as indicated by pollution roses. Full 
details of the local meteorology analysis and pollution roses are 
provided in the TSD.
iv. Modeling Information
    The EPA considered relying on two separate modeling demonstrations 
for the Muscatine area. Modeling performed by the State of Iowa for 
purposes of the control strategy and attainment demonstration for the 
area was submitted to EPA in May 2016. EPA later approved the 
attainment plan and modeling in a final action in November 2020 (85 FR 
73218). That final action has since been remanded without vacatur to 
EPA.\5\ The State of Iowa also submitted modeling pursuant to the 
SO2 DRR for LGS in January 2017. This DRR modeling was the 
basis for EPA's Round 3 designation of Attainment/Unclassifiable for 
Louisa County (containing LGS) in December 2017 (83 FR 1098). Both sets 
of modeling rely on permitted allowable emissions rates \6\ \7\ that 
were in place by the October 4, 2018, attainment date and were 
previously found by EPA to demonstrate attainment of the NAAQS as noted 
above. However, the EPA is not relying on Iowa's attainment 
demonstration modeling as a basis for our proposed determination, 
because that modeling may be revisited as part of the EPA's 
reconsideration action per the D.C. Circuit's remand of EPA's approval 
of Iowa's attainment plan. Rather, as discussed above, we are relying 
on the DRR modeling to provide a comparison between the much higher 
modeled emission rates at the sources and the actual recorded emissions 
to provide additional evidence that the entire area was attaining the 
NAAQs as of October 4, 2018.
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    \5\ The final approval action was challenged in the D.C. Cir. on 
January 15, 2021 and was placed in abeyance on February 3, 2021. 
Sierra Club v. EPA, No. 21-1022 (D.C. Cir.). EPA filed an unopposed 
motion to the court for a voluntary remand without vacatur and 
indicated that EPA would take a final reconsideration action no 
later than December 1, 2023. The D.C. Circuit granted EPA's motion 
on December 17, 2021.
    \6\ The permits containing the emissions limits also contain 
exemptions for periods of startup, shutdown, and cleaning.
    \7\ Monsanto was modeled with actual emissions for the Louisa 
County DRR modeling demonstration.
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v. Conclusion
    In sum, and as discussed further in the TSD, we propose to find 
that the weight of the available evidence indicates that the Muscatine 
area attained the 2010 1-hour SO2 NAAQS in the 2015-2017 
timeframe by the October 4, 2018 attainment date. Specifically, the 
significant reductions in emissions during the relevant time period 
from sources within the nonattainment area and a nearby source outside 
the nonattainment area, coupled with corresponding decreased monitored 
SO2 concentrations within the nonattainment area during that 
same time period lead us to our proposed determination that the area 
attained by its attainment date. Local meteorological data help confirm 
that the air quality monitors are unlikely to have missed high 
concentrations, and the available modeling information and emissions 
data of the nearby LGS source (which may not be reflected in the air 
quality monitoring data from within the nonattainment area) also 
supports the EPA's determination, as actual historical emissions from 
that source during the relevant time period were significantly below 
the emissions that were modeled to be consistent with attainment of the 
NAAQS.

IV. Proposed Action and Request for Public Comment

    The EPA conducted a weight-of-evidence analysis, described in 
detail above and in the TSD, to determine if the Muscatine 
SO2 nonattainment area attained the 2010 1-hour 
SO2 NAAQS by the October 4, 2018 attainment date by 
evaluating all available technical information and data relevant to the 
SO2 air quality (e.g., emissions, monitoring, meteorological 
data, and modeling) in the Muscatine, Iowa, area. Based on the analysis 
and information presented in this document and the TSD contained in

[[Page 3963]]

the docket for this action, the EPA proposes to determine that the 
Muscatine SO2 NAA attained the 2010 1-hour SO2 
standard by the applicable attainment date of October 4, 2018, 
consistent with CAA section 179(c)(1).
    In addition, this action, if finalized, will address EPA's 
obligation under a consent decree in Center for Biological Diversity, 
et al. v. Regan, which establishes a deadline of March 31, 2022 for the 
EPA to determine under CAA section 179(c) whether the Muscatine County 
SO2 nonattainment area attained the NAAQS by the October 4, 
2018 attainment date.\8\
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    \8\ Center for Biological Diversity, et al. v. Regan, No. 3:20-
cv-05436-EMC (N.D. Cal. June 25, 2021).
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    This proposed action does not constitute a redesignation of the 
Muscatine SO2 NAA to attainment for the 2010 1-hour 
SO2 NAAQS under CAA section 107(d)(3) because we have not 
yet approved a maintenance plan for the area as meeting the 
requirements of section 175A of the CAA and have not determined that 
the area has met the other CAA section 107(d)(3)(E) requirements for 
redesignation. The classification and designation status in 40 CFR part 
81 will remain nonattainment until the EPA has determined that Iowa has 
met the CAA requirements for redesignation to attainment for the 
Muscatine SO2 NAA.
    This is a proposed action and we are soliciting comments on this 
proposed action. Final rulemaking will occur after consideration of any 
comments.

V. Environmental Justice Concerns

    When the EPA establishes a new or revised NAAQS, the CAA requires 
the EPA to designate all areas of the U.S. as either nonattainment, 
attainment, or unclassifiable. Area designations address environmental 
justice concerns by ensuring that the public is properly informed about 
the air quality in an area.
    The EPA utilized the EJSCREEN tool to evaluate environmental and 
demographic indicators within the area. The tool outputs report is 
contained in the docket for this action. While the EPA's EJSCREEN tool 
demonstrates that demographic indicators are consistent or lower than 
national averages, there are vulnerable populations in the area 
including low-income populations and persons over 64 years of age.
    This action addresses EPA's determination, as required by the CAA, 
of whether the Muscatine County, Iowa, area attained the 2010 1-hour 
SO2 NAAQS by the relevant attainment date. This action 
proposes to determine an area has attained the NAAQS by the relevant 
attainment date, but it does not change the geographic status of the 
area nor does it impose additional or modify existing requirements on 
sources. Based on the information presented in this document and the 
associated technical support document, the EPA is proposing to 
determine that the air quality in the Muscatine County area is 
attaining the NAAQS. For these reasons, this proposed action does not 
result in disproportionately high and adverse human health or 
environmental effects on minority populations, low-income populations 
and/or indigenous peoples.

VI. Statutory and Executive Order Reviews

    This action proposes to determine an area has attained the NAAQS by 
the relevant attainment date and does not impose additional or modify 
existing requirements. For that reason, this action:
     Is not a significant regulatory action subject to review 
by the Office of Management and Budget under Executive Orders 12866 (58 
FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of the National Technology 
Transfer and Advancement Act (NTTA) because this rulemaking does not 
involve technical standards; and
     This action does not have disproportionately high and 
adverse human health or environmental effects on minority populations, 
low-income populations and/or indigenous peoples, as specified in 
Executive Order 12898 (59 FR 7629, February 16, 1994). The basis for 
this determination is contained in section V of this action, 
``Environmental Justice Concerns.''

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Reporting and recordkeeping 
requirements, Sulfur oxides.

    Dated: January 20, 2022.
Meghan A. McCollister,
Regional Administrator, Region 7.

    For the reasons stated in the preamble, the EPA proposes to amend 
40 CFR part 52 as set forth below:

PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

0
1. The authority citation for part 52 continues to read as follows:

    Authority: 42 U.S.C. 7401 et seq.

Subpart Q--Iowa

0
2. Revise Sec.  52.834 to read as follows:

Sec.  52.834  Control strategy: Sulfur dioxide.

    (a) Approval. On April 21, 1997, the Iowa Department of Natural 
Resources (IDNR) submitted a maintenance plan and redesignation request 
for the Muscatine County nonattainment area for the 1971 SO2 
national ambient air quality standard (NAAQS). The maintenance plan and 
redesignation request satisfy all applicable requirements of the Clean 
Air Act.
    (b) Determination of attainment by the attainment date. As of [date 
30 days after date of publication of the final rule in the Federal 
Register], the EPA has determined that the Muscatine, Iowa, 
SO2 nonattainment area has attained the 2010 1-hour 
SO2 primary NAAQS by the applicable attainment date of 
October 4, 2018.

[FR Doc. 2022-01497 Filed 1-25-22; 8:45 am]
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