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 Environmental Protection Agency 40 CFR Part 52
[EPA-R08-OAR-2023-0489; FRL-12135-02-R8]
 AGENCY: Environmental Protection Agency (EPA).
 ACTION: Final rule.
 SUMMARY: The Environmental Protection Agency (EPA) is partially approving and partially disapproving a regional haze state implementation plan (SIP) revision submitted by the State of Wyoming on August 10, 2022 (Wyoming's 2022 SIP submission), to address applicable requirements under the Clean Air Act (CAA) and the EPA's Regional Haze Rule (RHR) for the regional haze program's second implementation period. The EPA is taking this action pursuant to the CAA.
 DATES: This rule is effective on January 2, 2025.
 ADDRESSES: The EPA has established a docket for this action under Docket ID No. EPA-R08-OAR-2023-0489. All documents in the docket are listed on the 
                        *https://www.regulations.gov*
                         website. Although listed in the index, some information is not publicly available, 
                        *e.g.,*
                         Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, is not placed on the internet and will be publicly available only in hard copy form. Publicly available docket materials are available through 
                        *https://www.regulations.gov,*
                         or please contact the person identified in the 
                        **FOR FURTHER INFORMATION CONTACT**
                         section for additional availability information.
 FOR FURTHER INFORMATION CONTACT: Jaslyn Dobrahner, Air and Radiation 
                        ( print page 95122)
                        Division, EPA, Region 8, Mailcode 8ARD-IO, 1595 Wynkoop Street, Denver, Colorado 80202-1129, telephone number: (303) 312-6252; email address: 
                        *dobrahner.jaslyn@epa.gov.*


SUPPLEMENTARY INFORMATION: Throughout this document “we,” “us,” and “our” means the EPA. Table of Contents I. What is being addressed in this document? II. Summary of the Proposed Action, Public Comments, and the EPA's Rationale for Final Action III. Final Action IV. Statutory and Executive Order Reviews I. What is being addressed in this document? The EPA is partially approving and partially disapproving Wyoming's regional haze plan for the second implementation period. As required by section 169A of the CAA, the RHR calls for State and Federal agencies to work together to improve visibility in 156 national parks and wilderness areas, known as mandatory Class I Federal areas.[1]
                    
                     The rule requires the States, in coordination with the EPA, the National Park Service, the Fish and Wildlife Service, the Forest Service, and other interested parties, to develop and implement air quality protection plans to reduce the pollution that causes visibility impairment in mandatory Class I Federal areas. Visibility impairing pollutants include fine and coarse particulate matter (PM) (
                    *e.g.,*
                     sulfates, nitrates, organic carbon, elemental carbon, and soil dust) and their precursors (
                    *e.g.,*
                     sulfur dioxide (SO2), oxides of nitrogen (NOX), and, in some cases, volatile organic compounds (VOC) and ammonia (NH3)). As discussed in further detail in our proposed rule, this document, and the accompanying Response to Comments (RTC) document, the EPA finds that Wyoming submitted a regional haze SIP that does not meet all of the regional haze requirements for the second implementation period. The State's submission, the proposed rule, and the RTC document can be found in the docket for this action. II. Summary of the Proposed Action, Public Comments, and the EPA's Rationale for Final Action On August 10, 2022, Wyoming submitted a revision to its SIP to address regional haze for the second implementation period, in accordance with the requirements of the CAA's regional haze program established by CAA sections 169A and 169B and 40 CFR 51.308. On August 1, 2024, the EPA proposed to disapprove certain provisions of Wyoming's 2022 SIP submission.[2]
                    
                     Specifically, we proposed to disapprove the portions of Wyoming's 2022 SIP submission relating to 40 CFR 51.308(f)(2): long-term strategy; 40 CFR 51.308(f)(3): reasonable progress goals; and 40 CFR 51.308(i): Federal Land Manager (FLM) consultation. We also proposed to approve the portions of Wyoming's 2022 SIP submission relating to 40 CFR 51.308(f)(1): calculations of baseline, current, and natural visibility conditions, progress to date, and the uniform rate of progress; 40 CFR 51.308(f)(4): reasonably attributable visibility impairment; 40 CFR 51.308(f)(5) and 40 CFR 51.308(g): progress report requirements; and 40 CFR 51.308(f)(6): monitoring strategy and other implementation plan requirements. Consistent with section 110(k)(3) of the CAA, the EPA may partially approve portions of a submittal if those elements meet all applicable requirements and may disapprove the remainder so long as the elements are fully separable. Our August 1, 2024 proposed rule provided background on the requirements of the CAA and RHR, a summary of Wyoming's regional haze SIP submittals and related EPA actions, and the EPA's rationale for its proposed action. That background and rationale will not be restated in full here, although we briefly summarize the reasons for our partial disapproval of Wyoming's 2022 SIP submission in the paragraphs that follow. Our public comment period closed on September 3, 2024. During the public notice and comment period, we received more than 6,000 comments on our proposal. The full text of the comments received are included in the publicly posted docket associated with this action at 
                    *https://www.regulations.gov.*
                     Our RTC document, which is also included in the docket, provides full, detailed responses to all significant comments received and further explains the basis for our final action. In CAA section 169A(a)(1), Congress established the national goal of preventing any future and remedying any existing impairment of visibility in mandatory Class I Federal areas that results from manmade (anthropogenic) air pollution. The core component of a regional haze SIP submission for the second implementation period is a long-term strategy for making reasonable progress toward meeting that national goal. CAA section 169A(b)(2)(B), 40 CFR 51.308(f)(2). A state's long-term strategy must address regional haze in each Class I area within the state's borders and each Class I area outside the state that may be affected by emissions originating from within the state. It “must include the enforceable emissions limitations, compliance schedules, and other measures that are necessary to make reasonable progress, as determined pursuant to (f)(2)(i) through (iv).” 40 CFR 51.308(f)(2). The amount of progress that is “reasonable progress” is based on consideration of the four statutory factors in CAA section 169A(g)(1)—the costs of compliance, the time necessary for compliance, the energy and non-air quality environmental impacts of compliance, and the remaining useful life of any potentially affected sources [3]
                    
                    —in an evaluation of potential control measures for sources of visibility impairing pollutants, which is referred to as a “four-factor” analysis. In developing its long-term strategy, the state must document the technical basis, including modeling, monitoring, cost, engineering, and emissions information, on which it is relying to determine the measures that are necessary to make reasonable progress. 40 CFR 51.308(f)(2)(iii). Wyoming did not include any emission control measures, new or existing, in its long-term strategy for the regional haze second implementation period. As explained in section 3.A. of the RTC document, the CAA authorizes the EPA to substantively review states' SIP submissions for compliance with the statute and RHR to ensure progress towards the national visibility goal for Class I areas. Congress charged the EPA with exercising “federal oversight” over SIP submissions and “review[ing] all SIPs to ensure that the plans comply with the statute.” 
                    *Oklahoma*
                     v. 
                    *EPA,*
                     723 F.3d 1201, 1204 (10th Cir. 2013). The “EPA is left with more than the ministerial task of routinely approving SIP submissions.” 
                    *North Dakota*
                     v. 
                    *EPA,*
                     730 F.3d 750, 761 (8th Cir. 2013). Instead, the Agency's “review of a SIP extends not only to whether the state considered the necessary factors in its determination, but also to whether the determination is one that is reasonably moored to the CAA's provisions” and is “based on `reasoned analysis.' ” 
                    *Id.*
                     at 761, 766 (citing 
                    *Alaska Dep't of Envt. Conservation*
                     v. 
                    *EPA,*
                     540 U.S. 461 (2004)); 
                    *see also Wyoming*
                     v. 
                    *EPA,*
                     78 F.4th 1171, 1180-81 (10th Cir. 2023) (noting that “the Act provides for substantive and careful EPA review” of 
                    ( print page 95123)
                    SIP submissions and that “the EPA does not have to accept unreasonable analyses”). For the reasons stated in the proposed rule, this document, and in the RTC document, the EPA determines that Wyoming's 2022 SIP submission does not meet all of the requirements of the CAA and RHR. As detailed at length in our proposed rule and in the RTC document, we conclude that Wyoming's long-term strategy does not meet the requirements of CAA section 169A(b)(2) and 40 CFR 51.308(f)(2) on four independent grounds. First, Wyoming failed to consider the four statutory factors for the sources and associated units and pollutants listed in table 1, despite determining that these sources may contribute to visibility impairment at Class I areas. In some instances, Wyoming provided no justification for the lack of four-factor analysis. In others, Wyoming improperly relied on planned but unenforceable source retirements or on the presence of existing emission control measures at a source, without providing adequate technical documentation of the effectiveness of those existing controls or a sufficient indication that additional controls would not be cost-effective or reasonable. For the reasons detailed in our proposed rule and in the RTC document,[4]
                    
                     the State's reasoning does not justify its decision not to conduct four-factor analyses for these sources, as required under CAA section 169A(g)(1) and 40 CFR 51.308(f)(2). Therefore, we cannot conclude that Wyoming's long-term strategy includes all the measures that are necessary to make reasonable progress. Table 1—Sources, Units, and Associated Pollutants That May Affect Visibility at Class I Areas Where No Four-Factor Analysis Was Performed
Source
Unit(s)
Associated 
                             pollutant(s)Jim Bridger 
                            *(PacifiCorp)*
1, 2
NO
                            X
                            , SO
                            2
                            , PM.Jim Bridger 
                            *(PacifiCorp)*
3, 4
SO
                            2
                            , PM.Naughton 
                            *(PacifiCorp)*
1, 2
NO
                            X
                            , SO
                            2
                            , PM.Naughton 
                            *(PacifiCorp)*
3
NO
                            X
                            , PM.Dave Johnston 
                            *(PacifiCorp)*
1, 2
NO
                            X
                            , SO
                            2
                            , PM.Dave Johnston 
                            *(PacifiCorp)*
4
PM.Wyodak 
                            *(PacifiCorp)*
1
NO
                            X
                            , SO
                            2
                            , PM.Laramie River Station 
                            *(Basin Electric)*
1-3
PM.Laramie Portland Cement 
                            *(Mountain Cement Company)*
Kilns 1, 2
SO
                            2
                            .Elk Basin Gas Plant 
                            *(Contango Resources, Inc.)*
Engines (9) and incinerator
PM.Elk Basin Gas Plant 
                            *(Contango Resources, Inc.)*
Engines (9)
SO
                            2
                            .Elk Basin Gas Plant 
                            *(Contango Resources, Inc.)*
Incinerator
NO
                            X
                            .
 Although we stated in our proposed rule that Wyoming failed to justify the lack of a four-factor analysis of NOX
                     and PM emission control measures for Lost Cabin Gas Plant, we are not carrying that finding forward into our final rule. Based on our consideration of a comment we received and on our further review of Wyoming's 2022 SIP submission, we conclude that because the State's Q/d analysis [5]
                    
                     shows that the possible impact of the facility's NOX
                     and PM emissions on visibility at Class I areas is very small, Wyoming reasonably elected to conduct a four-factor analysis only for SO2
                     control measures for this facility, and not for NOX
                     and PM control measures. Therefore, the lack of a four-factor analysis of NOX
                     and PM emissions controls for Lost Cabin Gas Plant is not a reason for our disapproval of the State's long-term strategy.[6] Second, Wyoming relied on unsupported rationales and failed to document the technical basis (including cost, engineering, and emissions information) [7]
                    
                     of its decision not to include any emission control measures in its long-term strategy for the sources listed in table 2. In evaluating the cost of potential control measures for some of these sources, Wyoming used unsubstantiated cost inputs, relied on unjustifiably low estimates of control technology efficiencies, and miscalculated the level of achievable emission reductions. These methodological errors undercut the technical support for Wyoming's cost analyses and the State's resulting determinations that control measures for these sources would not be cost-effective. In other instances, the State provided no reasoning, technical data, or cost information to support its conclusions. For the reasons detailed in our proposed rule and in the RTC document,[8]
                    
                     these methodological errors and unsupported technical bases, considered collectively, prevent the EPA from determining that the State's long-term strategy is adequate to make reasonable progress toward meeting the national visibility goal. Table 2—Sources, Units, and Associated Pollutants Where the State Failed To Document the Technical Basis of Its Determinations of the Emission Reduction Measures Necessary To Make Reasonable Progress
Source
Unit(s)
Associated 
                             pollutant(s)Dave Johnston 
                            *(PacifiCorp)*
4
SO
                            2
                            .Laramie Portland Cement 
                            *(Mountain Cement Company)*
Kilns 1, 2
NO
                            X
                            .( print page 95124)Green River Works 
                            *(TATA Chemicals)*
Calciner 1, Calciner 2
NO
                            X
                            , PM.Elk Basin Gas Plant 
                            *(Contango Resources, Inc.)*
Engines (9)
NO
                            X
                            .Elk Basin Gas Plant 
                            *(Contango Resources, Inc.)*
Incinerator
SO
                            2
                            .Lost Cabin Gas Plant 
                            *(Burlington Resources)*
Trains 2, 3
SO
                            2
                            .
 Third, Wyoming unreasonably rejected emission control measures for Elk Basin Gas Plant and Cheyenne Fertilizer Facility (listed in table 3). Wyoming made no determination that these control measures were not cost-effective (based on the cost per ton of emissions reduced); [9]
                    
                     nor did it explain why these measures were otherwise unwarranted under the four statutory factors.[10]
                    
                     The cost-effectiveness values of these control measures are below the level that the EPA and the states generally found to be reasonable in the first implementation period, even without adjusting for inflation. Instead of justifying its rejection of these control measures based on the four statutory factors, Wyoming cited declining emission trends, its belief that these sources will not increase their emissions during the second implementation period, and the presence of existing control technologies at the facilities (which the State notably did not determine to be effective for purposes of making reasonable progress).[11]
                    
                     As we explained in the context of the 2017 Regional Haze Rule revisions, “a state that elects to consider an additional factor . . . must consider it in a reasonable way that does not undermine or nullify the role of the four statutory factors in determining what controls are necessary to make reasonable progress.” [12]
                    
                     Wyoming improperly relied on these other considerations to reject controls that its four-factor analyses showed to be cost-effective and otherwise reasonable. Within its 2022 SIP submission, Wyoming conceded that based on the four-factor analyses it conducted for Elk Basin Gas Plant and Cheyenne Fertilizer Facility, these sources may warrant further analysis of the measures necessary to make reasonable progress.[13]
                    
                     Wyoming stated it would submit more detailed analyses in the context of its regional haze second implementation progress report due in 2025. However, nothing in the CAA or RHR allows states to avoid their obligation to determine the measures necessary to make reasonable progress through consideration of the four statutory factors by delaying decision-making to a future date.[14]
                    
                     For these reasons, and as further detailed in our proposed rule and in the RTC document,[15]
                    
                     we find that Wyoming's long-term strategy does not include the measures necessary to make reasonable progress because Wyoming unreasonably rejected control measures for Elk Basin Gas Plant and Cheyenne Fertilizer Facility. Table 3—Sources, Units, and Associated Pollutants and Emission Control Technology Where the State Unreasonably Rejected Emission Reduction Measures
Source
Unit(s)
Associated pollutant(s)
Emission control
                             technologyElk Basin Gas Plant 
                            *(Contango Resources, Inc.)*
Engines (9)
NO
                            X
Low emission combustion.Cheyenne Fertilizer Facility 
                            *(Dyno Nobel, Inc.)*
ENG004, ENG005 (engines)
NO
                            X
Low emission combustion.Cheyenne Fertilizer Facility 
                            *(Dyno Nobel, Inc.)*
CTW001, CTW003 (cooling towers)
PM
Upgraded Mist Eliminators.
 
 
 Fourth, as explained in our proposed rule and in the RTC document,[16]
                    
                     the overarching justifications that Wyoming provided for not including any emission control measures in its long-term strategy are either not adequately supported or lack foundation in the CAA and RHR. Following its evaluation and rejection of emission control measures for individual sources, Wyoming explained its overall reasoning for not including any measures in its long-term strategy to make reasonable progress for the regional haze second implementation period.[17]
                    
                     The State asserted that such measures could impose economic hardships on sources, negatively affect rural communities, force energy producers out of the market, harm ratepayers, and cause grid instability. However, the State's reliance on these purported economic impacts does not reflect reasoned analysis because Wyoming provided no analyses, data, or other evidence to support its generalized and unsubstantiated assertions. Similarly, Wyoming provided no support for its declaration that requiring additional controls would not lead to visibility improvements at Class I areas. Finally, Wyoming pointed to contributions to visibility impairment from sources outside its control; past and projected emission reductions resulting from other regulatory programs; and that the State's Class I areas are below the adjusted uniform rate of progress (a tracking metric to help states assess the amount of progress they are making towards the national visibility goal over time in each Class I area). As further explained in our proposed rule and in the RTC document, Wyoming's consideration of those factors was not reasonably moored to the statute and regulations. In addition to disapproving the State's long-term strategy, we are disapproving Wyoming's reasonable progress goals under 40 CFR 51.308(f)(3) and its consultation with Federal Land Managers under 40 CFR 51.308(i). As detailed in our proposed rule and in the RTC document,[18]
                    
                     compliance with these requirements is dependent on compliance with the long-term strategy provisions in 40 CFR 51.308(f)(2). III. Final Action For the reasons stated in the proposed rule, in the RTC document, and in this document, we are partially approving and partially disapproving Wyoming's 2022 SIP submission. We are disapproving the following components of Wyoming's 2022 SIP submission relating to CAA section 169A: Long-term strategy (40 CFR 51.308(f)(2));
                Reasonable progress goals (40 CFR 51.308(f)(3)); and
                FLM consultation (40 CFR 51.308(i)). We are approving the following components of Wyoming's 2022 SIP submission relating to CAA section 169A: Calculations of baseline, current, and natural visibility conditions, progress to date, and uniform rate of progress (40 CFR 51.308(f)(1));
                Reasonably attributable visibility impairment (40 CFR 51.308(f)(4));
                Progress report requirements (40 CFR 51.308(f)(5) and 40 CFR 51.308(g)); and
                Monitoring strategy and other implementation plan requirements (40 CFR 51.308(f)(6)). IV. Statutory and Executive Order Reviews Under the CAA, the Administrator is required to approve a SIP submission that complies with the provisions of the CAA and applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, EPA's role is to approve state choices, provided that they meet the criteria of the CAA. Accordingly, this action partially approves and partially disapproves state law as meeting Federal requirements and does not impose additional requirements beyond those imposed by state law. 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 14094 (88 FR 21879, April 11, 2023);
                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 inExecutive Order 13132 (64 FR 43255, August 10, 1999);
                Is not subject toExecutive Order 13045 (62 FR 19885, April 23, 1997) because it approves a state program;
                Is not a significant regulatory action subject toExecutive Order 13211 (66 FR 28355, May 22, 2001); and
                Is not subject to requirements of section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because application of those requirements would be inconsistent with the CAA. In addition, the SIP is not approved to apply on any Indian reservation land or in any other area where EPA or an Indian Tribe has demonstrated that a Tribe has jurisdiction. In those areas of Indian country, the rule does not have Tribal implications and will not impose substantial direct costs on Tribal governments or preempt Tribal law as specified by Executive Order 13175 (65 FR 67249, November 9, 2000). Executive Order 12898 (Federal Actions To Address Environmental Justice in Minority Populations and Low-Income Populations, 59 FR 7629, Feb. 16, 1994) directs Federal agencies to identify and address “disproportionately high and adverse human health or environmental effects” of their actions on communities with environmental justice (EJ) concerns to the greatest extent practicable and permitted by law. Executive Order 14096 (Revitalizing Our Nation's Commitment to Environmental Justice for All, 88 FR 25251, April 26, 2023) builds on and supplements E.O. 12898 and defines EJ as, among other things, the just treatment and meaningful involvement of all people, regardless of income, race, color, national origin, or Tribal affiliation, or disability in agency decision-making and other Federal activities that affect human health and the environment. The State did not evaluate EJ considerations as part of its SIP submittal; the CAA and applicable implementing regulations neither prohibit nor require such an evaluation. EPA performed an EJ analysis, as is described in the proposed action 89 FR 63030 (August 1, 2024) in the section titled, “Environmental Justice.” The analysis was done for the purpose of providing additional context and information about this rulemaking to the public, not as a basis of the action. In addition, there is no information in the record upon which this decision is based inconsistent with the stated goal 
                    ( print page 95126)
                    of E.O. 12898/14096 of achieving EJ for communities with EJ concerns. This action is subject to the Congressional Review Act, and EPA will submit a rule report to each House of the Congress and to the Comptroller General of the United States. This action is not a “major rule” as defined by 5 U.S.C. 804(2). Under section 307(b)(1) of the CAA, petitions for judicial review of this action must be filed in the United States Court of Appeals for the appropriate circuit by January 31, 2025. Filing a petition for reconsideration by the Administrator of this final rule does not affect the finality of this action for the purposes of judicial review nor does it extend the time within which a petition for judicial review may be filed, and shall not postpone the effectiveness of such rule or action. This action may not be challenged later in proceedings to enforce its requirements (see section 307(b)(2)). List of Subjects in 40 CFR Part 52 Environmental protection
Air pollution control
Carbon monoxide
Greenhouse gases
Incorporation by reference
Intergovernmental relations
Lead
Nitrogen dioxide
Ozone
Particulate matter
Reporting and recordkeeping requirements
Sulfur oxides
Volatile organic compounds
 Dated: November 22, 2024. KC Becker, Regional Administrator, Region 8.
 For the reasons stated in the preamble, the Environmental Protection Agency is amending 40 CFR part 52 as follows: PART 52—APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS
 1.The authority citation for part 52 continues to read as follows: Authority:
                        42 U.S.C. 7401 
                            *et seq.* Subpart ZZ—Wyoming
 2.In § 52.2620, the table in paragraph (e) is amended by adding and entry for “(36) XXXVI” at the end of the table to read as follows: § 52.2620
  
 (e) * * * Rule No.
Rule title
State
                                     effective 
                                     date
EPA
                                     effective 
                                     date
Final rule
                                     citation/date
Comments*         *         *         *         *         *         *(36) XXXVI
Wyoming State Implementation Plan, Second Planning Period
2022
1/2/2025
[insert 
                                    **Federal Register**
                                     citation], 12/2/2024
Excluding the following: Chapters 3.4, 7, 8, 10, 11, 12, 13, 14, 15, and appendix C-E, G-M. EPA disapproved the portions of Wyoming's 2022 SIP submission relating to CAA section 169A and 40 CFR 51.308(f)(2): long-term strategy; 40 CFR 51.308(f)(3): reasonable progress goals; and 40 CFR 51.308(i): FLM consultation.


# Footnotes

1.
    
                         
                        *See*40 CFR part 81, subpart D. Back to Citation
 2.
    
                         89 FR 63030 (August 1, 2024). Back to Citation
 3.
    
                         CAA section 169A(g)(1); 40 CFR 51.308(f)(2)(i). Back to Citation
 4.
    
                         89 FR at 63056-62; RTC document, sections 7, 8, 14. Back to Citation
 5.
    
                         Q/d values represent the ratio of an individual source's annual emissions of visibility-impairing emission precursors (NOX, SO2, and PM10) in combined tons (“Q”) divided by the distance in kilometers (“d”) between the source and a Class I area. The larger the Q/d value, the greater the source's expected effect on visibility impairment in that Class I area. Back to Citation
 6.
    
                         Section 8.K. of the RTC document contains our full response to the comment we received on this issue. Back to Citation
 7.
    
                         
                        *See*40 CFR 51.308(f)(2)(iii). Back to Citation
 8.
    
                         89 FR at 63062-65; RTC document, sections 3.C., 7, 8. Back to Citation
 9.
    
                         For the Cheyenne Fertilizer Facility, as with Elk Basin Gas Plant, Wyoming did not determine that the cost/ton values of the NOX
                         and PM measures it evaluated were unreasonable. However, Wyoming concluded that the capital costs of installing PM controls (upgraded mist eliminators) on two cooling towers were not justified given what the State determined—without explanation—to be the “minute” amount of PM reductions at stake. Wyoming 2022 SIP submission at 191. We do not find this justification to be sufficient in light of the mist eliminators' cost-effectiveness values (
                        *i.e.,*
                         cost per ton of emissions reduced), which align with the cost/ton values that were generally found to be reasonable during the first implementation period. 
                        *See*
                         89 FR at 63065 & n.158. Nor did Wyoming explain why the reduction in PM emissions that could be achieved by upgraded mist eliminators was not necessary to make reasonable progress. As we explained in the 2019 Guidance, capital costs considered in isolation may not provide complete information about the potential reasonableness of a control measure. 2019 Guidance at 39. Indeed, Wyoming itself conceded that “[b]ased on this four-factor analysis, this facility may warrant further analysis of emission controls to reach reasonable progress.” Wyoming 2022 SIP submission at 191. Back to Citation
 10.
    
                         For Elk Basin Gas Plant, Wyoming did not explicitly determine, based on its four-factor analysis, that NOX
                         controls are not necessary to make reasonable progress. Wyoming 2022 SIP submission at 172 (“Considering the four factors above, as well as emission trends and permit conditions, this facility may warrant further analysis of emission controls to reach reasonable progress.”). For NOX
                         and PM controls at the Cheyenne Fertilizer Facility, Wyoming asserted that “[o]verall, considering the four factors discussed above, the Division does not believe that additional emissions control technology on the Cooper Engines . . . or Cooling Towers is necessary to make reasonable progress at this time.” Wyoming 2022 SIP submission at 191. However, aside from pointing to the capital costs of PM control measures, Wyoming did not explain 
                        *how*
                         it reached that conclusion. Back to Citation
 11.
    
                         Wyoming 2022 SIP submission at 171-72, 191. Wyoming also noted that the engines at the Cheyenne Fertilizer Facility are natural gas-fired. 
                        *Id.*
                         at 191. However, Wyoming did not explain how combustion of natural gas mitigates the need for NOX
                         emissions reductions measures or why low-emission combustion (the control technology for these engines that the State evaluated through four-factor analysis) is not necessary to make reasonable progress. As detailed in sections 7.B. and 8.A.ii. of the RTC document, combustion of natural gas does not itself render a source effectively controlled for NOX
                         emissions. Back to Citation
 12.
    
                         EPA, Responses to Comments on Protection of Visibility: Amendments to Requirements for State Plans; Proposed Rule, December 2016, at 186 (available in the docket for this action). Back to Citation
 13.
    
                         Wyoming 2022 SIP submission at 172, 191. Back to Citation
 14.
    
                         
                        *Cf. NRDC*
                         v. 
                        *EPA,*
                         22 F.3d 1125, 1134 (D.C. Cir. 1994) (noting that SIPs must “contain[ ] something more than a mere promise to take appropriate but unidentified measures in the future”). In addition, because progress reports due in 2025 will not take the form of SIP revisions that must be approved or disapproved by the EPA, it is not clear how Wyoming could evaluate and potentially impose federally enforceable emission reduction measures at these sources through that process. 
                        *See generally*40 CFR 51.308(g). Back to Citation
 15.
    
                         89 FR at 63065; RTC document, sections 5, 8.I., 8.L. Back to Citation
 16.
    
                         89 FR at 63065-67; RTC document, sections 3.B., 3.G., 4, and 9. Back to Citation
 17.
    
                         Wyoming 2022 SIP submission, Chapter 13: Decisions on What Control Measures are Necessary to Make Reasonable Progress. Back to Citation
 18.
    
                         89 FR at 63067-68; RTC document, sections 3.B., 10 (reasonable progress goals). 89 FR at 63069-70; RTC document, sections 3.E., 11 (FLM consultation). Back to Citation


[FR Doc. 2024-27942 Filed 11-29-24; 8:45 am] BILLING CODE 6560-50-P