# Approval and Promulgation of Air Quality Implementation Plans; Nevada; Regional Haze State Implementation Plan for the Second Implementation Period
**AGENCY:**
Environmental Protection Agency (EPA).
**ACTION:**
Proposed rule.
**SUMMARY:**
The Environmental Protection Agency (EPA) is proposing to approve portions of the regional haze state implementation plan (SIP) revisions submitted by the Nevada Division of Environmental Protection (NDEP) on August 12, 2022 (“2022 Nevada Regional Haze Plan”) and on May 28, 2025 (“2025 SIP Supplement”), as satisfying applicable requirements under the Clean Air Act (CAA) and the EPA's Regional Haze Rule (RHR) for the program's second implementation period. These revisions address the requirement that states must periodically revise their long-term strategies for making reasonable progress towards the national goal of preventing any future, and remedying any existing, anthropogenic impairment of visibility, including regional haze, in mandatory Class I Federal areas. The revisions also address other applicable requirements for the second implementation period of the regional haze program. The EPA is taking this action pursuant to CAA sections 110 and 169A.
**DATES:**
Written comments must be received on or before November 24, 2025.
(1) *Addresses:* Submit your comments, identified by Docket ID No. EPA-R09-OAR-2025-0101 at *https://www.regulations.gov* . For comments submitted at *Regulations.gov* , follow the online instructions for submitting comments. 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, please contact the person identified in the *FOR FURTHER INFORMATION CONTACT* section. For 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* . If you need assistance in a language other than English or if you are a person with a disability who needs a reasonable accommodation at no cost to you, please contact the person identified in the *FOR FURTHER INFORMATION CONTACT* section.
**FOR FURTHER INFORMATION CONTACT:**
Emily Millar, Geographic Strategies & Modeling Section (ARD-2-2), Planning & Analysis Branch, Air & Radiation Division, EPA Region IX, 75 Hawthorne Street, San Francisco, CA 94105, telephone number: (213) 244-1882, email address: *[email protected]* .
**SUPPLEMENTARY INFORMATION:**
Throughout this document, “we,” “us,” and “our” refer to the EPA.
**Table of Contents**
I. What action is the EPA proposing?
II. Background and Requirements for Regional Haze Plans
A. Regional Haze Background
B. Roles of Agencies in Addressing Regional Haze
III. Requirements for Regional Haze Plans for the Second Implementation Period
A. Long-Term Strategy for Regional Haze
B. Reasonable Progress Goals
C. Monitoring Strategy and Other State Implementation Plan Requirements
D. Requirements for Periodic Reports Describing Progress Towards the Reasonable Progress Goals
E. Requirements for State and Federal Land Manager Coordination
IV. The EPA's Evaluation of Nevada's Regional Haze Submissions for the Second Implementation Period
A. Background on Nevada's First Implementation Period SIP Submission
B. Nevada's Second Implementation Period SIP Submissions and the EPA's Evaluation
C. Identification of Class I Areas
D. Calculations of Baseline, Current, and Natural Visibility Conditions; Progress to Date; and the Uniform Rate of Progress
E. Long-Term Strategy for Regional Haze
F. Reasonable Progress Goals
G. Additional Monitoring To Assess Reasonably Attributable Visibility Impairment
H. Monitoring Strategy and Other Implementation Plan Requirements
I. Requirements for Periodic Reports Describing Progress Towards the Reasonable Progress Goals
J. Requirements for State and Federal Land Manager Coordination
V. Proposed Action
VI. Incorporation by Reference
VII. Statutory and Executive Order Reviews
**I. What action is the EPA proposing?**
On August 12, 2022, NDEP submitted the 2022 Nevada Regional Haze Plan, titled “Nevada Regional Haze State Implementation Plan for the Second Planning Period” as a revision to the Nevada SIP to address regional haze for the second implementation period. [^1] NDEP made this SIP submission to satisfy the requirements of the CAA's regional haze program pursuant to CAA sections 169A and 169B and 40 CFR 51.308. The EPA found this submission complete on August 16, 2022. [^2] On July 27, 2023, NDEP withdrew the reasonable progress determinations for Tracy Generating Station's Piñon Pine Unit (also known variously as Tracy Unit 4 and Tracy Unit 7) and North Valmy Generating Station's Unit 1 and Unit 2. [^3] On May 28, 2025, NDEP submitted the 2025 SIP Supplement, titled “Nevada Regional Haze Revision to the State Implementation Plan for the Second Planning Period,” which includes revised reasonable progress determinations for those two sources. [^4] The 2025 Supplement also includes updated permits for three sources, replacing those submitted as part of the 2022 Nevada Regional Haze Plan. [^5] At this time the EPA is not proposing to act on the revised reasonable progress determinations for Tracy Unit 7 (Piñon Pine Unit 4) and North Valmy Generating Station's Unit 1 and Unit 2, which were included in the 2025 SIP Supplement. However, the EPA is proposing to find that the 2022 Nevada Regional Haze Plan, as revised by the July 27, 2023 partial withdrawal, and the permits submitted in appendix A of the 2025 SIP Supplement, meets the applicable statutory and regulatory requirements. Thus, we propose to approve the 2022 Nevada Regional Haze Plan (excluding the portions withdrawn on July 27, 2023) and appendix A (“Air Quality Permits Incorporated by Reference”) of the 2025 Supplement (collectively “the Plan”) into the Nevada SIP.
[^1] Letter dated August 12, 2022, from Greg Lovato, Administrator, NDEP, to Martha Guzman, Regional Administrator, U.S. Environmental Protection Agency Region 9 (submitted electronically August 12, 2022).
[^2] Letter dated August 16, 2022, from Elizabeth Adams, Director, Air and Radiation Division, EPA Region IX, to Greg Lovato, Administrator, NDEP.
[^3] Letter dated July 27, 2023, from Jennifer L. Carr, Administrator, NDEP, to Martha Guzman, Regional Administrator, U.S. Environmental Protection Agency Region 9 (submitted electronically August 2, 2023).
[^4] Letter dated May 23, 2025, from Jennifer L. Carr, Administrator, NDEP, to Josh F.W. Cook, Regional Administrator, U.S. Environmental Protection Agency Region 9 (submitted electronically May 27, 2025).
[^5] 2025 SIP Supplement, appendix A.
**II. Background and Requirements for Regional Haze Plans**
A detailed history and background of the regional haze program is provided in multiple prior EPA proposal actions. [^6] For additional background on the 2017 RHR revisions, please refer to section III. Overview of Visibility Protection Statutory Authority, Regulation, and Implementation of “Protection of Visibility: Amendments to Requirements for State Plans” of the 2017 RHR. [^7] The following is an abbreviated history and background of the regional haze program and 2017 RHR as it applies to the current action.
[^6] See 90 FR 13516 (March 24, 2025).
[^7] See 82 FR 3078 (January 10, 2017), located at *https://www.federalregister.gov/documents/2017/01/10/2017-00268/protection-of-visibility-amendments-to-requirements-for-State-plans#h-16* ).
**A. Regional Haze Background**
In the 1977 CAA Amendments, Congress created a program for protecting visibility in the nation's mandatory Class I Federal areas, which include certain national parks and wilderness areas. [^8] The CAA establishes as a national goal the “prevention of any future, and the remedying of any existing, impairment of visibility in mandatory class I Federal areas which impairment results from manmade air pollution.” [^9]
[^8] CAA 169A. Areas statutorily designated as mandatory Class I Federal areas consist of national parks exceeding 6,000 acres, wilderness areas and national memorial parks exceeding 5,000 acres, and all international parks that were in existence on August 7, 1977. CAA 162(a). There are 156 mandatory Class I areas. The list of areas to which the requirements of the visibility protection program apply is in 40 CFR part 81, subpart D.
[^9] CAA 169A(a)(1).
Regional haze is visibility impairment that is produced by a multitude of anthropogenic sources and activities which are located across a broad geographic area and that emit pollutants that impair visibility. 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 (SO <sub>2</sub> ), nitrogen oxides (NO <sub>X</sub> ), and, in some cases, volatile organic compounds (VOC) and ammonia (NH <sub>3</sub> )). Fine particle precursors react in the atmosphere to form PM <sub>2.5</sub> , which impairs visibility by scattering and absorbing light. Visibility impairment reduces the perception of clarity and color, as well as visible distance. [^10]
[^10] There are several ways to measure the amount of visibility impairment, *i.e.,* haze. One such measurement is the deciview, which is the principal metric used by the RHR. Under many circumstances, a change in one deciview will be perceived by the human eye to be the same on both clear and hazy days. The deciview is unitless. It is proportional to the logarithm of the atmospheric extinction of light, which is the perceived dimming of light due to it being scattered and absorbed as it passes through the atmosphere. Atmospheric light extinction (b [^ext] ) is a metric used for expressing visibility and is measured in inverse megameters (Mm <sub>−1</sub> ). The formula for the deciview is 10 ln (b [^ext] )/10 Mm <sub>−1</sub> ). 40 CFR 51.301.
To address regional haze visibility impairment, the 1999 RHR established an iterative planning process that requires both states in which Class I areas are located and states “the emissions from which may reasonably be anticipated to cause or contribute to any impairment of visibility” in a Class I area to periodically submit SIP revisions to address such impairment. [^11]
[^11] CAA 169A(b)(2). The RHR expresses the statutory requirement for states to submit plans addressing out-of-state class I areas by providing that states must address visibility impairment “in each mandatory Class I Federal area located outside the State that may be affected by emissions from within the State.” 40 CFR 51.308(d), (f). See also 40 CFR 51.308(b), (f) (establishing submission dates for iterative regional haze SIP revisions); 64 FR 35714, 35768 (July 1, 1999).
On January 10, 2017, the EPA promulgated revisions to the RHR, which apply for the second and subsequent implementation periods. [^12] The reasonable progress requirements as revised in the 2017 rulemaking (referred to here as the 2017 RHR Revisions) are codified at 40 CFR 51.308(f).
[^12] 82 FR 3078 (January 10, 2017).
**B. Roles of Agencies in Addressing Regional Haze**
Because the air pollutants and pollution affecting visibility in Class I areas can be transported over long distances, successful implementation of the regional haze program requires long-term, regional coordination among multiple jurisdictions and agencies that have responsibility for Class I areas and the emissions that impact visibility in those areas. To address regional haze, states need to develop strategies in coordination with one another, considering the effect of emissions from one jurisdiction on the air quality in another. Five regional planning organizations (RPOs), which include representation from state and Tribal governments, the EPA, and FLMs, were developed in the lead-up to the first implementation period to address regional haze. RPOs evaluate technical information to better understand how emissions from State and Tribal land impact Class I areas across the country, pursue the development of regional strategies to reduce emissions of particulate matter and other pollutants leading to regional haze, and help states meet the consultation requirements of the RHR.
The Western Regional Air Partnership (WRAP), one of the five RPOs, is a collaborative effort of state governments, Tribal governments, and various Federal agencies established to initiate and coordinate activities associated with the management of regional haze, visibility, and other air quality issues in the western corridor of the United States. Member states (listed alphabetically) include: Alaska, Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, North Dakota, Oregon, South Dakota, Utah, Washington, and Wyoming. The Federal partner members of WRAP are the EPA, U.S. National Parks Service (NPS), U.S. Fish and Wildlife Service (FWS), and U.S. Forest Service (USFS). There are also 468 federally recognized Tribes within the WRAP region.
**III. Requirements for Regional Haze Plans for the Second Implementation Period**
Under the CAA and the EPA's regulations, all 50 states, the District of Columbia, and the U.S. Virgin Islands were required to submit regional haze SIP revisions satisfying the applicable requirements for the second implementation period of the regional haze program by July 31, 2021. Each state's SIP must contain a long-term strategy for making reasonable progress toward meeting the national goal of remedying any existing and preventing any future anthropogenic visibility impairment in Class I areas. [^13] To this end, 40 CFR 51.308(f) lays out the process by which states determine what constitutes their long-term strategies, with the order of the requirements in section 40 CFR 51.308(f)(1) through (3) generally mirroring the order of the steps in the reasonable progress analysis [^14] and (f)(4) through (6) containing additional, related requirements. Broadly speaking, a state first must identify the Class I areas within the state and determine the Class I areas outside the state in which visibility may be affected by emissions from the state. These are the Class I areas that must be addressed in the state's long-term strategy. [^15] For each Class I area within its borders, a state must then calculate the baseline (five-year average period of 2000-2004), current, and natural visibility conditions ( *i.e.,* visibility conditions without anthropogenic visibility impairment) for that area, as well as the visibility improvement made to date and the “uniform rate of progress” (URP). [^16] The URP is the linear rate of progress needed to attain natural visibility conditions, assuming a starting point of baseline visibility conditions in 2004 and ending with natural conditions in 2064. This linear interpolation is used as 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. Each state having a Class I area and/or emissions that may affect visibility in a Class I area must then develop a long-term strategy that includes the enforceable emissions limitations, compliance schedules, and other measures that are necessary to make reasonable progress in such areas. A reasonable progress determination is based on applying the four factors in CAA section 169A(g)(1) to sources of visibility-impairing pollutants that the state has selected to assess for controls for the second implementation period. Additionally, as further explained below, the RHR at 40 CFR 51.308(f)(2)(iv) separately provides five “additional factors” [^17] that states must consider in developing their long-term strategies. [^18] A state evaluates potential emissions reduction measures for those selected sources and determines which are necessary to make reasonable progress. Those measures are then incorporated into the state's long-term strategy. After a state has developed its long-term strategy, it then establishes RPGs for each Class I area within its borders by modeling the visibility impacts of all reasonable progress controls at the end of the second implementation period, *i.e.,* in 2028, as well as the impacts of other requirements of the CAA. The RPGs include reasonable progress controls not only for sources in the state in which the Class I area is located, but also for sources in other states that contribute to visibility impairment in that area. The RPGs are then compared to the baseline visibility conditions and the URP to ensure that progress is being made towards the statutory goal of preventing any future and remedying any existing anthropogenic visibility impairment in Class I areas. [^19] There are additional requirements in the rule, including FLM consultation, that apply to all visibility protection SIPs and SIP revisions. [^20]
[^13] CAA 169A(b)(2)(B).
[^14] The EPA explained in the 2017 RHR Revisions that we were adopting new regulatory language in 40 CFR 51.308(f) that, unlike the structure in 51.308(d), “tracked the actual planning sequence.” 82 FR 3078, 3091 (January 10, 2017).
[^15] See 40 CFR 51.308(f), (f)(2).
[^16] See 40 CFR 51.308(f)(1).
[^17] The five “additional factors” for consideration in 40 CFR 51.308(f)(2)(iv) are distinct from the four factors listed in CAA section 169A(g)(1) and 40 CFR 51.308(f)(2)(i) that states must consider and apply to sources in determining reasonable progress.
[^18] See 40 CFR 51.308(f)(2).
[^19] 40 CFR 51.308(f)(2)-(3).
[^20] See, *e.g.,* 40 CFR 51.308(i).
**A. Long-Term Strategy for Regional Haze**
While states have discretion to choose any source selection methodology that is reasonable, whatever choices they make should be reasonably explained. To this end, 40 CFR 51.308(f)(2)(i) requires that a state's SIP submission include “a description of the criteria it used to determine which sources or groups of sources it evaluated.” The technical basis for source selection, which may include methods for quantifying potential visibility impacts such as emissions divided by distance metrics, trajectory analyses, residence time analyses, and/or photochemical modeling, must also be appropriately documented, as required by 40 CFR 51.308(f)(2)(iii).
Once a state has selected the set of sources, the next step is to determine the emissions reduction measures for those sources that are necessary to make reasonable progress for the second implementation period. [^21] This is accomplished by considering the four factors—“the costs of compliance, the time necessary for compliance, and the energy and non-air quality environmental impacts of compliance, and the remaining useful life of any existing source subject to such requirements.” [^22] The EPA has explained that the four-factor analysis is an assessment of potential emissions reduction measures ( *i.e.,* control options) for sources; “use of the terms `compliance' and `subject to such requirements' in section 169A(g)(1) strongly indicates that Congress intended the relevant determination to be the requirements with which sources would have to comply to satisfy the CAA's reasonable progress mandate.” [^23] Thus, for each source it has selected for four-factor analysis, [^24] a state must consider a “meaningful set” of technically feasible control options for reducing emissions of visibility impairing pollutants. [^25]
[^21] The CAA provides that, “[i]n determining reasonable progress there shall be taken into consideration” the four statutory factors. CAA 169A(g)(1). However, in addition to four-factor analyses for selected sources, groups of sources, or source categories, a state may also consider additional emissions reduction measures for inclusion in its long-term strategy, *e.g.,* from other newly adopted, on-the-books, or on-the-way rules and measures for sources not selected for four-factor analysis for the second planning period.
[^22] CAA 169A(g)(1).
[^23] 82 FR 3078, 3091 (January 10, 2017).
[^24] “Each source” or “particular source” is used here as shorthand. While a source-specific analysis is one way of applying the four factors, neither the statute nor the RHR requires states to evaluate individual sources. Rather, states have “the flexibility to conduct four-factor analyses for specific sources, groups of sources or even entire source categories, depending on state policy preferences and the specific circumstances of each state.” 82 FR at 3088 (January 10, 2017).
[^25] Id. at 3088 (January 10, 2017).
The EPA has also explained that, in addition to the four statutory factors, states have flexibility under the CAA and RHR to reasonably consider visibility benefits as an additional factor alongside the four statutory factors. [^26] Ultimately, while states have discretion to reasonably weigh the factors and to determine what level of control is needed, 40 CFR 51.308(f)(2)(i) provides that a state “must include in its implementation plan a description of . . . how the four factors were taken into consideration in selecting the measure for inclusion in its long-term strategy.”
[^26] See, *e.g.,* Responses to Comments on Protection of Visibility: Amendments to Requirements for State Plans; Proposed Rule (81 FR 26942, May 4, 2016), Docket Number EPA-HQ-OAR-2015-0531, U.S. Environmental Protection Agency, p. 186.
As explained above, 40 CFR 51.308(f)(2)(i) requires states to determine the emissions reduction measures for sources that are necessary to make reasonable progress by considering the four factors. Pursuant to 40 CFR 51.308(f)(2), measures that are necessary to make reasonable progress towards the national visibility goal must be included in a state's long-term strategy and in its SIP. If the outcome of a four-factor analysis is that an emissions reduction measure is necessary to make reasonable progress towards remedying existing or preventing future anthropogenic visibility impairment, that measure must be included in the SIP.
The characterization of information on each of the factors is also subject to the documentation requirement in 40 CFR 51.308(f)(2)(iii). The reasonable progress analysis is a technically complex exercise, and also a flexible one that provides states with bounded discretion to design and implement approaches appropriate to their circumstances. Given this flexibility, 40 CFR 51.308(f)(2)(iii) plays an important function in requiring a state to document the technical basis for its decision making so that the public and the EPA can comprehend and evaluate the information and analysis the state relied upon to determine what emissions reduction measures must be in place to make reasonable progress. The technical documentation must include the modeling, monitoring, cost, engineering, and emissions information on which the state relied to determine the measures necessary to make reasonable progress.
Additionally, the RHR at 40 CFR 51.3108(f)(2)(iv) separately provides five “additional factors” [^27] that states must consider in developing their long-term strategies: (1) Emissions reductions due to ongoing air pollution control programs, including measures to address reasonably attributable visibility impairment; (2) measures to reduce the impacts of construction activities; (3) source retirement and replacement schedules; (4) basic smoke management practices for prescribed fire used for agricultural and wildland vegetation management purposes and smoke management programs; and (5) the anticipated net effect on visibility due to projected changes in point, area, and mobile source emissions over the period addressed by the long-term strategy.
[^27] The five “additional factors” for consideration in 40 CFR 51.308(f)(2)(iv) are distinct from the four factors listed in CAA section 169A(g)(1) and 40 CFR 51.308(f)(2)(i) that states must consider and apply to sources in determining reasonable progress.
Because the air pollution that causes regional haze crosses state boundaries, 40 CFR 51.308(f)(2)(ii) requires a state to consult with other states that also have emissions that are reasonably anticipated to contribute to visibility impairment in a given Class I area. If a state, pursuant to consultation, agrees that certain measures ( *e.g.,* a certain emissions limitation) are necessary to make reasonable progress at a Class I area, it must include those measures in its SIP. [^28] Additionally, the RHR requires that states that contribute to visibility impairment at the same Class I area consider the emissions reduction measures the other contributing states have identified as being necessary to make reasonable progress for their own sources. [^29] If a state has been asked to consider or adopt certain emissions reduction measures, but ultimately determines those measures are not necessary to make reasonable progress, that state must document in its SIP submission the actions taken to resolve the disagreement. [^30] Under all circumstances, a state must document in its SIP submission all substantive consultations with other contributing states. [^31]
[^28] 40 CFR 51.308(f)(2)(ii)(A).
[^29] 40 CFR 51.308(f)(2)(ii)(B).
[^30] 40 CFR 51.308(f)(2)(ii)(C).
[^31] 40 CFR 51.308(f)(2)(ii)(C).
**B. Reasonable Progress Goals**
Reasonable progress goals “measure the progress that is projected to be achieved by the control measures states have determined are necessary to make reasonable progress based on a four-factor analysis.” [^32]
[^32] 82 FR 3078, 3091 (January 10, 2017).
For the second implementation period, the RPGs are set for 2028. RPGs are not enforceable targets. [^33] While states are not legally obligated to achieve the visibility conditions described in their RPGs, 40 CFR 51.308(f)(3)(i) requires that “[t]he long-term strategy and the RPGs must provide for an improvement in visibility for the most impaired days since the baseline period and ensure no degradation in visibility for the clearest days since the baseline period.”
[^33] 40 CFR 51.308(f)(3)(iii).
RPGs may also serve as a metric for assessing the amount of progress a state is making towards the national visibility goal. To support this approach, the RHR requires states with Class I areas to compare the 2028 RPG for the most impaired days to the corresponding point on the URP line (representing visibility conditions in 2028 if visibility were to improve at a linear rate from conditions in the baseline period of 2000-2004 to natural visibility conditions in 2064). If the most impaired days RPG in 2028 is above the URP ( *i.e.,* if visibility conditions are improving more slowly than the rate described by the URP), each state that contributes to visibility impairment in the Class I area must demonstrate, based on the four-factor analysis required under 40 CFR 51.308(f)(2)(i), that no additional emissions reduction measures would be reasonable to include in its long-term strategy. [^34] To this end, 40 CFR 51.308(f)(3)(ii) requires that each state contributing to visibility impairment in a Class I area that is projected to improve more slowly than the URP provide “a robust demonstration, including documenting the criteria used to determine which sources or groups [of] sources were evaluated and how the four factors required by paragraph (f)(2)(i) were taken into consideration in selecting the measures for inclusion in its long-term strategy.”
[^34] 40 CFR 51.308(f)(3)(ii).
**C. Monitoring Strategy and Other State Implementation Plan Requirements**
Section 51.308(f)(6) requires states to have certain strategies and elements in place for assessing and reporting on visibility. Individual requirements under this section apply either to states with Class I areas within their borders, states with no Class I areas but that are reasonably anticipated to cause or contribute to visibility impairment in any Class I area, or both. Compliance with the monitoring strategy requirement may be met through a state's participation in the Interagency Monitoring of Protected Visual Environments (IMPROVE) monitoring network, which is used to measure visibility impairment caused by air pollution at the 156 Class I areas covered by the visibility program. [^35]
[^35] 40 CFR 51.308(f)(6), (f)(6)(i), (f)(6)(iv).
All states' SIP submissions must provide for procedures by which monitoring data and other information are used to determine the contribution of emissions from within the state to regional haze visibility impairment in affected Class I areas, as well as a statewide inventory documenting such emissions. [^36] All states' SIPs must also provide for any other elements, including reporting, recordkeeping, and other measures, that are necessary for states to assess and report on visibility. [^37]
[^36] 40 CFR 51.308(f)(6)(ii), (iii), (v).
[^37] 40 CFR 51.308(f)(6)(vi).
**D. Requirements for Periodic Reports Describing Progress Towards the Reasonable Progress Goals**
Section 51.308(f)(5) requires a state's regional haze SIP revision to address the requirements of paragraphs 40 CFR 51.308(g)(1) through (5) so that the plan revision due in 2021 will serve also as a progress report addressing the period since submission of the progress report for the first implementation period. The regional haze progress report requirement is designed to inform the public and the EPA about a state's implementation of its existing long-term strategy and whether such implementation is in fact resulting in the expected visibility improvement. [^38] To this end, every state's SIP revision for the second implementation period is required to assess changes in visibility conditions and describe the status of implementation of all measures included in the state's long-term strategy, including BART and reasonable progress emissions reduction measures from the first implementation period, and the resulting emissions reductions. [^39]
[^38] See 81 FR 26942, 26950 (May 4, 2016); 82 FR 3078, 3119 (January 10, 2017).
[^39] 40 CFR 51.308(g)(1) and (2).
**E. Requirements for State and Federal Land Manager Coordination**
CAA section 169A(d) requires that before a state holds a public hearing on a proposed regional haze SIP revision, it must consult with the appropriate FLM or FLMs; pursuant to that consultation, the state must include a summary of the FLMs' conclusions and recommendations in the notice to the public. Consistent with this statutory requirement, the RHR also requires that states “provide the [FLM] with an opportunity for consultation, in person and at a point early enough in the State's policy analyses of its long-term strategy emission reduction obligation so that information and recommendations provided by the [FLM] can meaningfully inform the State's decisions on the long-term strategy.” [^40] For the EPA to evaluate whether FLM consultation meeting the requirements of the RHR has occurred, the SIP submission should include documentation of the timing and content of such consultation. The SIP revision submitted to the EPA must also describe how the state addressed any comments provided by the FLMs. [^41] Finally, a SIP revision must provide procedures for continuing consultation between the state and FLMs regarding the state's visibility protection program, including development and review of SIP revisions, five-year progress reports, and the implementation of other programs having the potential to contribute to impairment of visibility in Class I areas. [^42]
[^40] 40 CFR 51.308(i)(2).
[^41] 40 CFR 51.308(i)(3).
[^42] 40 CFR 51.308(i)(4).
**IV. The EPA's Evaluation of Nevada's Regional Haze Submissions for the Second Implementation Period**
**A. Background on Nevada's First Implementation Period SIP Submission**
NDEP submitted its regional haze plan for the first implementation period to the EPA on November 18, 2009. The requirements for regional haze SIP submissions for the first implementation period are contained in 40 CFR 51.308(d) and (e). [^43] On March 26, 2012, the EPA approved all portions of the 2009 plan, but did not act on the BART determination for Reid Gardner Generating Station (RGGS) for NO <sub>X</sub> . [^44] On August 23, 2012, we partially approved and partially disapproved this remaining portion of the plan. Specifically, the EPA approved NDEP's selection of a NO <sub>X</sub> emissions limit of 0.20 pounds per million British thermal units (lb/MMBtu) as BART for RGGS Units 1 and 2. We disapproved two provisions of NDEP's BART determination for NO <sub>X</sub> at RGGS: the NO <sub>X</sub> emissions limit for Unit 3 and the compliance method for all three units. As a result, the EPA promulgated a FIP, which replaced the disapproved SIP provisions by establishing a BART emissions limit for NO <sub>X</sub> of 0.20 lb/MMBtu at Unit 3, and a 30-day averaging period for compliance on a heat input-weighted basis across all three units. [^45] The EPA later rescinded the RGGS FIP because RGGS Units 1-3 were permanently decommissioned. [^46]
[^43] 40 CFR 51.308(b).
[^44] 77 FR 17334 (March 26, 2012).
[^45] 78 FR 53033 (August 28, 2013).
[^46] 83 FR 54053 (October 26, 2018).
Pursuant to 40 CFR 51.308(g), NDEP was also responsible for submitting a five-year progress report as a SIP revision for the first implementation period, which it did on November 18, 2014. The EPA approved the progress report into the Nevada SIP on August 8, 2017. [^47]
[^47] 82 FR 37020, (August 8, 2017).
**B. Nevada's Second Implementation Period SIP Submissions and the EPA's Evaluation**
In accordance with CAA sections 169A and the RHR at 40 CFR 51.308(f), on August 12, 2022, NDEP submitted the 2022 Nevada Regional Haze Plan to address its regional haze obligations for the second implementation period, which runs through 2028. NDEP made the 2022 Nevada Regional Haze SIP submission available for public comment on June 23, 2022. NDEP received and responded to public comments and included the comments and responses to those comments in its submission. On July 27, 2023, NDEP withdrew the reasonable progress determinations for the Tracy Generating Station's Piñon Pine Unit and North Valmy Generating Station's Unit 1 and Unit 2 and related portions of the 2022 Nevada Regional Haze Plan.
On May 27, 2025, NDEP submitted the 2025 SIP Supplement that includes the revised reasonable progress determinations. NDEP made the 2025 SIP Supplement available for public comment on February 28, 2025. NDEP received and responded to public comments and included the comments and responses to those comments in its submission. [^48] The following sections describe the Plan, including analyses conducted by the WRAP and Nevada's determinations based on those analyses, NDEP's assessment of progress made since the first implementation period in reducing emissions of visibility impairing pollutants, and the visibility improvement progress at its Class I area and nearby Class I areas. This notice also provides the EPA's evaluation of the Plan against the requirements of the CAA and RHR for the second implementation period of the regional haze program.
[^48] 2025 SIP Supplement, section 6.2 and appendix G.
**C. Identification of Class I Areas**
Section 169A(b)(2) of the CAA requires each state in which any Class I area is located or “the emissions from which may reasonably be anticipated to cause or contribute to any impairment of visibility” in a Class I area to have a plan for making reasonable progress toward the national visibility goal. The RHR implements this statutory requirement at 40 CFR 51.308(f), which provides that each state's plan “must address regional haze in each mandatory Class I Federal area located within the State and in each mandatory Class I Federal area located outside the State that may be affected by emissions from within the State,” and (f)(2), which requires each state's plan to include a long-term strategy that addresses regional haze in such Class I areas.
The EPA concluded in the 1999 RHR that “all [s]tates contain sources whose emissions are reasonably anticipated to contribute to regional haze in a Class I area,” [^49] and this determination was not changed in the 2017 RHR. Critically, the statute and regulation both require that the cause-or-contribute assessment consider all emissions of visibility impairing pollutants from a state, as opposed to emissions of a particular pollutant or emissions from a certain set of sources.
[^49] 64 FR 35714, 35721 (July 1, 1999).
Nevada has one mandatory Class I Federal area within its borders, the Jarbidge Wilderness Area located within the Humboldt National Forest in the northeastern portion of Nevada.
For the second implementation period, the Regional Haze Planning Work Group of the WRAP performed technical analyses, [^50] including source apportionment modeling [^51] and weighted emissions potential analyses [^52] to help assess source and state-level contributions to visibility impairment at Jarbidge Wilderness Area and at Class I areas in adjacent states. NDEP determined that the following Class I areas in neighboring states are affected the most by emissions originating in Nevada: Grand Canyon, Arizona; Ike's Backbone (Pine Mountain and Mazatzal), Arizona; Desolation Wilderness, California; Craters of the Moon, ID; Hells Canyon, Oregon; and Zion Canyon, Utah. NDEP used the source apportionment modeling results to analyze significant contributors at Jarbidge Wilderness Area. [^53] The overall SO <sub>2</sub> emissions sources for the most impaired days are primarily from the states of California, Idaho, Oregon and Washington. For all these states, contributions to sulfate are primarily from non-EGU and industrial sources. Remaining anthropogenic source sectors outside of point and mobile sources is the next largest contributor among these states. Nevada's EGU sector is also one of the most significant contributors to ammonium sulfate extinction at Jarbidge Wilderness Area. For nitrate, the dominant WRAP source area contributions for the most impaired days are from California, Idaho, Oregon, and Washington. Mobile source emissions are the dominant source category for NO <sub>X</sub> emissions, followed by non-EGU and area sources.
[^50] The WRAP's Emissions Inventory and Modeling Protocols Subcommittee, along with its contractor, Ramboll Inc., performed these modeling analyses for the WRAP states, including Nevada. NDEP also provided updated WRAP and WESTAR links in a clarification letter. See Letter dated September 8, 2025, from Andrew Tucker, Chief, Bureau of Air Quality Planning, NDEP, to Rynda Kay, Manager, Geographic Strategies & Modeling Section, U.S. Environmental Protection Agency Region 9.
[^51] The CAMx photochemical model version 7.0 with the Particle Source Apportionment Technology (PSAT) tool was applied at a regional level to separate U.S. anthropogenic contributions from those of fire, natural, and international anthropogenic contributions for a current period (2014-2018) and a future year in 2028. See section 4.3 of the 2022 Nevada Regional Haze Plan.
[^52] The Weighted Emissions Potential (WEP) tool is an analysis technique that identifies the predominant emission source regions contributing haze-forming pollutants at each Class I area based on 5 years of historical meteorology during the most impaired days. See chapter 1 and section 4.4 of the 2022 Nevada Regional Haze Plan.
[^53] 2022 Nevada Regional Haze Plan, sections 4.3.2 and 4.3.3.
NDEP also used the source apportionment modeling results to determine which Class I areas in adjacent states might be affected by emissions from Nevada sources. NDEP identified the rank and percentage of the total modeled concentration due to SO <sub>2</sub> and NO <sub>X</sub> emissions from sources within Nevada to the IMPROVE monitors representing all Class I areas in the five adjacent states, and evaluated total contributions compared to total light extinction at each Class I area. [^54] The highest contribution from Nevada anthropogenic sources to an out-of-state Class I area's sulfate extinction in 2028 is Craters of the Moon at 1.15 percent. Among all evaluated Class I areas, EGU, non-EGU, and remaining anthropogenic sources tend to be the largest contributors to sulfate extinction. The highest contribution to an out-of-state Class I area's nitrate extinction in 2028 is Desolation Wilderness at 6.16 percent. Additionally, among all evaluated Class I areas, NDEP indicated that the mobile source sector is generally the largest contributor to nitrate extinction.
[^54] 2022 Nevada Regional Haze Plan, tables 4-4, 4-5, and 4-6.
In sum, NDEP determined that sources and emissions within the state contribute to visibility impairment at both Jarbidge Wilderness Area and at certain Class I areas in nearby states. [^55] Furthermore, the state took part in the consultation process as a member of the Regional Haze Planning Work Group (RHPWG) of the WRAP. [^56] As discussed in further detail below, Nevada also identified sources using a Q/d > 5 analysis [^57] to conduct a four-factor analysis, and determined reasonable measures that could be implemented by 2028, considering the cost of compliance, the time necessary for compliance, the energy and non-air quality environmental impacts, and the remaining useful life of any potentially affected sources. We therefore propose to find that Nevada appropriately identified Class I areas that may be affected be emissions from the state.
[^55] Id.
[^56] 2022 Nevada Regional Haze Plan, appendix E.
[^57] Q/d represents a source's annual emissions in tons (Q) divided by the distance in kilometers (d) between the source and the nearest Class I area. For regional haze purposes, only primary visibility-impairing pollutants were included in a source's total Q: NO <sub>X</sub> , SO <sub>2</sub> , and PM <sub>10</sub> . Nevada used emissions from the 2014v2 NEI to calculate a source's total Q.
**D. Calculations of Baseline, Current, and Natural Visibility Conditions; Progress to Date; and the Uniform Rate of Progress**
Section 51.308(f)(1) requires states to determine the following for “each mandatory Class I Federal area located within the State”: baseline visibility conditions for the most impaired and clearest days, natural visibility conditions for the most impaired and clearest days, progress to date for the most impaired and clearest days, the differences between current visibility conditions and natural visibility conditions, and the URP. This section also provides the option for states to propose adjustments to the URP line for a Class I area to account for visibility impacts from anthropogenic sources outside the United States and/or the impacts from wildland prescribed fires that were conducted for certain, specified objectives. [^58]
[^58] 40 CFR 51.308(f)(1)(vi)(B).
In the 2022 Nevada Regional Haze Plan, NDEP noted that Jarbidge Wilderness Area has 2000-2004 baseline visibility conditions of 2.56 deciviews on the 20 percent clearest days and 8.73 deciviews on the 20 percent most impaired days. [^59] NDEP calculated an estimated natural visibility conditions of 1.14 deciviews on the 20 percent clearest days and 5.23 deciviews on the 20 percent most impaired days for the Jarbidge Wilderness Area. [^60] The current visibility conditions, which are based on 2014-2018 monitoring data, were 1.84 deciviews on the clearest days and 7.97 deciviews on the most impaired days, [^61] which are 0.70 deciviews and 2.74 deciviews greater than natural conditions on the respective sets of days. [^62] The progress to date, subtracting current conditions from baseline conditions, yields a 0.72 deciview improvement for the 20 percent clearest days and 0.76 deciview improvement for the 20 percent most impaired days. [^63]
[^59] 2022 Nevada Regional Haze Plan, section 2.2.
[^60] Id., tables 2-1 and 2-2. NDEP stated elsewhere in Chapter 2 that natural visibility on the 20 percent most impaired days for the Jarbidge Wilderness Area is 7.39 deciviews. However, in Chapter 6, NDEP clarified that this 7.39 deciviews is the value used for the adjusted URP and includes international impacts and prescribed fire impacts.
[^61] Id., section 2.4 and table 2-3.
[^62] Id. NDEP mistakenly calculated the difference for the most impaired days relative to the adjusted URP, rather than natural conditions, yielding a difference of 0.58 deciviews. The correct difference of 2.74 deciviews can be derived by subtracting natural conditions (5.23 deciviews) from current conditions (7.97 deciviews).
[^63] Id. table 2-3.
NDEP chose to adjust its URP for international anthropogenic impacts and to account for the impacts of wildland prescribed fires using adjustments developed by the WRAP. [^64] The WRAP/WAQS Regional Haze modeling platform used scaled 2014 NEI wildland prescribed fire data for purposes of calculating the URP adjustments. WRAP used the results from the CAMx 2028OTBa2 High-Level Source Apportionment (H-L SA) run to determine pollutant concentrations attributable to international emissions and to prescribed fire. These concentrations were then used in a relative sense: the modeled relative effect of removing each of these emissions categories was applied to projections of 2028 concentrations. This gave a reduced 2028 concentration, and the reduction was taken as the contribution of prescribed fire and international emissions for use in adjusting the URP. The international and prescribed fire contributions were therefore calculated in a manner consistent with each other and with the 2028 projections. This approach is consistent with the default method described in the EPA's September 2019 regional haze modeling Technical Support Document (“EPA 2019 Modeling TSD”) [^65] and with the source apportionment approach described in the EPA's 2018 Visibility Tracking Guidance. [^66] Two different adjusted glidepath options, “International Emissions Only (A)” and “International Emissions + Wildland Rx Fire (B)”, were made available on the WRAP Technical Support System (TSS) [^67] to adjust the URP glidepath end points projections at 2064 for Class I Federal areas on the most impaired days. NDEP used the “International Emissions + Wildland Rx Fire (B)” option to adjust the URP for Jarbidge. [^68] The inclusion of international emissions added 2.0 dv to the 2064 URP end point, and the wildland prescribed fire added an another 0.2 dv, resulting in a 7.4 dv adjusted URP value for 2064. Based on this adjustment, NDEP calculated an annual URP of 0.022 deciviews per year needed to reach natural visibility on the 20 percent most impaired days. [^69]
[^64] Id. sections 2.6 and 6.9.1.
[^65] Memorandum from Richard A. Wayland, Director, Air Quality Assessment Division, EPA, to Regional Air Division Directors, Subject: “Availability of Modeling Data and Associated Technical Support Document for the EPA's Updated 2028 Visibility Air Quality Modeling,” September 19, 2019, available at *https://www.epa.gov/visibility/technical-guidance-tracking-visibility-progress-second-implementation-period-regional,* direct link: *https://www.epa.gov/visibility/technical-support-document-epas-updated-2028-regional-haze-modeling* .
[^66] Memorandum from Richard A. Wayland, Director, Air Quality Assessment Division, EPA, to Regional Air Division Directors, Subject: “Technical Guidance on Tracking Visibility Progress for the Second Implementation Period of the Regional Haze Program,” December 20, 2018, available at *https://www.epa.gov/sites/default/files/2018-12/documents/technical_guidance_tracking_visibility_progress.pdf* .
[^67] WRAP Technical Support System, *http://views.cira.colostate.edu/tssv2/* . The specific WRAP procedures for adjusting the URP are described in “Procedures for Making Visibility Projections and Adjusting Glidepaths using the WRAP-WAQS 2014 Modeling Platform (October 21, 2021, updated final draft),” available at *https://views.cira.colostate.edu/iwdw/docs/WAQS_and_WRAP_Regional_Haze_spec_sheets.aspx,* direct link: *https://views.cira.colostate.edu/docs/IWDW/PlatformDocs/WRAP_2014/2028_Vis_Proj_Glidepath_Adj_20211021_draft_final.pdf* .
[^68] 2022 Nevada Regional Haze Plan, section 6.9.1 and Figure 6-2.
[^69] Id. section 2.6.
The EPA is proposing to find that the Nevada Regional Haze Plan meets the requirements of 40 CFR 51.308(f)(1) related to the calculations of baseline, current, and natural visibility conditions; progress to date; the differences between current visibility conditions and natural visibility conditions, and the URP for the second implementation period.
**E. Long-Term Strategy for Regional Haze**
Each state having a Class I area within its borders or emissions that may affect visibility in a Class I area must develop a long-term strategy for making reasonable progress towards the national visibility goal. After considering the four statutory factors, all measures that are determined to be necessary to make reasonable progress must be in the long-term strategy. In developing its long-term strategies, a state must also consider the five additional factors in 40 CFR 51.308(f)(2)(iv). As part of its reasonable progress determinations, the state must describe the criteria used to determine which sources or group of sources were evaluated in a four-factor analysis for the second implementation period and how the four factors were taken into consideration in selecting the emissions reduction measures for inclusion in the long-term strategy. [^70]
[^70] 40 CFR 51.308(f)(2)(iii).
States may rely on technical information developed by the RPOs of which they are members to select sources for four-factor analysis and to conduct that analysis, as well as to satisfy the documentation requirements under 40 CFR 51.308(f). Where an RPO has performed source selection and/or four-factor analyses (or considered the five additional factors in 40 CFR 51.308(f)(2)(iv)) for its member states, those states may rely on the RPO's analyses for the purpose of satisfying the requirements of 40 CFR 51.308(f)(2)(i) so long as the states have a reasonable basis to do so and all state participants in the RPO process have approved the technical analyses. [^71] States may also satisfy the requirement of 40 CFR 51.308(f)(2)(ii) to engage in interstate consultation with other states that have emissions that are reasonably anticipated to contribute to visibility impairment in a given Class I area under the auspices of intra- and inter-RPO engagement.
[^71] Id.
The consultation requirements of 40 CFR 51.308(f)(2)(ii) provide that states must consult with other states that are reasonably anticipated to contribute to visibility impairment in a Class I area to develop and coordinate emissions management strategies containing the emissions reduction measures that are necessary to make reasonable progress. Section 51.308(f)(2)(ii)(A) and (B) require states to consider the emissions reduction measures identified by other states as necessary for reasonable progress and to include agreed upon measures in their SIPs, respectively. Section 51.308(f)(2)(ii)(C) speaks to what happens if states cannot agree on what measures are necessary to make reasonable progress.
The following sections summarize NDEP's long-term strategy for the second planning period, as set forth in the 2022 Nevada Regional Haze Plan. The EPA's evaluation with respect to the requirements of § 51.308(f)(2) is provided in section IV.E.7.
**1. Determination of Which Pollutants To Consider**
In Chapter 3 of the 2022 Nevada Regional Haze Plan, NDEP provided summaries of its base year (2014) and projected (2028) emissions inventories for visibility impairing pollutants. In Chapter 4 of the 2022 Nevada Regional Haze Plan, NDEP provided the results of visibility and source apportionment modeling performed by WRAP. Based on this information and analyses, in Chapter 5 of the 2022 Nevada Regional Haze Plan, NDEP chose to consider NO <sub>X</sub> , SO <sub>2</sub> , and PM <sub>10</sub> in its source selection and four factor analyses.
**2. Source Selection**
NDEP used a Q/d [^72] threshold of five based on the 2014 National Emissions Inventory (NEI) Version 2 (2014v2) NO <sub>X</sub> , SO <sub>2</sub> , and PM <sub>10</sub> emissions, which resulted in a list of eight sources, as shown in table 1. [^73] These eight sources are: RGGS, North Valmy Generating Station, McCarran International Airport, Lhoist North America Apex Plant, Nevada Cement Fernley Plant, Tracy Generating Station, TS Power Plant, and Graymont Pilot Peak Plant.
[^72] Q/d represents a source's annual emissions in tons per year (tpy) (Q) divided by the distance in kilometers (km) (d) between the source and the nearest Class I area.
[^73] 2022 Nevada Regional Haze Plan, chapter 5.
| | Nearest Class I area (CIA) | CIA | Total Q | Distance | Q/d |
| --- | --- | --- | --- | --- | --- |
| RGGS | Grand Canyon NP | AZ | 6,944 | 84 | 82.56 |
| North Valmy Generating Station | Jarbidge Wilderness Area | NV | 12,173 | 162 | 75.10 |
| McCarran International Airport | Grand Canyon NP | AZ | 2,770 | 107 | 25.97 |
| Lhoist North America Apex Plant | Grand Canyon NP | AZ | 1,662 | 88 | 18.84 |
| Nevada Cement Fernley Plant | Desolation Wilderness | CA | 1,482 | 102 | 14.55 |
| Tracy Generating Station | Desolation Wilderness | CA | 683 | 82 | 8.33 |
| TS Power Plant | Jarbidge Wilderness Area | NV | 834 | 131 | 6.39 |
| Graymont Pilot Peak Plant | Jarbidge Wilderness Area | NV | 673 | 131 | 5.13 |
NDEP screened out three of the eight sources listed above prior to conducting four-factor analyses. As explained in in section IV.A. of this document, NDEP screened out RGGS because it ceased operation and was completely decommissioned and dismantled. NDEP also screened out McCarran International Airport, now named the Harry Reid International Airport, because the vast majority of emissions are due to aircraft takeoffs, landings, and ground movement, falling outside of the local air agencies' scope of authority. Additionally, the allowable emissions for NO <sub>X</sub> , SO <sub>2</sub> , and PM <sub>10</sub> listed in the operating permit for the airport yielded a Q/d of 1.35, which was below NDEP's Q/d threshold of five. [^74] NDEP also removed TS Power Plant as the facility is operating BACT controls for NO <sub>X</sub> , SO <sub>2</sub> , and PM <sub>10</sub> . [^75] The TS Power Plant has one pulverized coal, dry bottom boiler with a gross capacity of 220 megawatts (MW). NDEP also provided a demonstration to show that the BACT controls are not necessary to make reasonable progress, because historical and projected emission rates for NO <sub>X</sub> , SO <sub>2</sub> , and PM <sub>10</sub> remain low and consistent, making it reasonable to assume that the source will continue to implement its existing measures and will not increase its emissions rates. [^76]
[^74] Id. table 5-2.
[^75] Table 5-39 of the 2022 Nevada Regional Haze Plan lists the existing controls that reduce visibility impairing pollutants at the facility, along with the corresponding BACT emission limits that can be found in the facility's air quality operating permit (Permit No. AP4911-2502).
[^76] 2022 Nevada Regional Haze Plan, section 5.4.6 and appendix B.3.
**3. Overall Approach to Four-Factor Analyses**
The remaining five sources that NDEP identified in the source selection step to require a four-factor analysis elected to submit their own four-factor analyses to evaluate existing controls and consider potential additional control measures that may be necessary to achieve reasonable progress. For the majority of the sources, NDEP requested additional information to supplement the initial four-factor analyses submitted by sources, resulting in multiple response letters from the sources to bolster the documentation for the four-factor analysis. Based on its review of these analyses and applying a cost-effectiveness threshold of $10,000 per ton of pollutant reduced, Nevada made a “Reasonable Progress Control Determination” for each relevant unit and pollutant. [^77] In addition, for each unit and pollutant where it determined that no additional control measures are necessary to make reasonable progress at a source, NDEP evaluated whether existing control measures implemented at the source are necessary to make reasonable progress.
[^77] Appendix B of the 2022 Nevada Regional Haze Plan contains all documentation of Nevada's reasonable progress conclusions each source, including the Reasonable Progress Control Determinations, four-factor analyses, and any subsequent response letters.
**4. Summary of Four-Factor Analyses**
**a. North Valmy Generating Station**
The North Valmy Generating Station is an electric generating facility owned by NV Energy (NVE) consisting of two coal-fired boilers that provide high pressure steam to steam turbine generators used to produce electricity. [^78] The facility screened in with a Q/d value of 75.14, and the nearest Class I area is Jarbidge Wilderness Area at 162 kilometers away.
[^78] 2022 Nevada Regional Haze Plan, section 5.5 and appendix B.6.
In the 2022 Nevada Regional Haze Plan, NVE committed to shutting down and permanently ceasing operation at both units at North Valmy by December 31, 2028. The effective closure date was incorporated into the consideration of the remaining useful life for each potential new measure considered for the North Valmy units. NDEP had relied on a closure date of December 31, 2028 for Units 1 and 2 as necessary to achieve reasonable progress.
However, as explained in the 2025 SIP Supplement, changes in the energy landscape along with transmission system reliability considerations in Nevada necessitated reconsideration of the retirement of North Valmy Units 1 and 2 by December 31, 2028. In August 2023, NVE filed an application for the Fifth Amendment to the 2021 Joint Integrated Resource Plan (IRP) with the Public Utilities Commission of Nevada (PUCN), seeking approval to convert the existing coal fueled plant at North Valmy Generating Station to a natural gas-fueled plant and continue operating it to 2049. In March 2024, the PUCN approved proceeding with these projects at North Valmy. NDEP withdrew the reasonable progress determination for North Valmy Generating Station on July 27, 2023, and then submitted a new reasonable progress determination for North Valmy Generating Station as part of the 2025 SIP Supplement on May 28, 2025. The EPA is not proposing to act on the revised reasonable progress determination for North Valmy Generating Station in the 2025 SIP Supplement at this time.
**b. Tracy Generating Station**
Tracy Generating Station is an electric generating facility owned by NVE that consists of one conventional, pipeline natural gas-fired 113 MW steam boiler (Unit 3); two pipeline natural gas and distillate-fired combustion turbines at 83.5 MW each (Units 5 and 6); one pipeline natural gas-fired combined cycle unit at 107 MW with 23 MW duct burners (Unit 7, also known as Piñon Pine Unit 4), and two pipeline natural gas-fired combined cycle units at 254 MW each (Units 32 and 33). [^79] The facility screened in with a Q/d value of 8.33, and the nearest Class I area is Desolation Wilderness, California at 81 kilometers away. NDEP screened out Units 5 and 6 from further consideration of potential new control measures based on low utilization and low emissions. [^80] In addition, NDEP screened out Units 32 and 33 based on existing effective controls (Dry Low NO <sub>X</sub> combustor and SCR) and low emissions. [^81]
[^79] 2022 Nevada Regional Haze Plan, section 5.6 and appendix B.5.
[^80] See 2022 Nevada Regional Haze Plan, table 5-13 for the baseline emissions for Tracy Units 5, 6, 32, and 33. Average NO <sub>X</sub> emissions for Units 5, 6, 32, and 33 are 12, 10.6, 38.5, and 37.5 tpy, respectively. Average SO <sub>2</sub> emissions for Units 5, 6, 32, and 33 are 0.3, 0.2, 4, and 4 tpy, respectively. Average PM <sub>10</sub> emissions for Units 5, 6, 32, and 33 are 1, 0.8, 24.3, 23.8 tpy, respectively.
[^81] Id.
NDEP evaluated Tracy Unit 3 for potential new control measures for NO <sub>X</sub> emissions considering the four statutory factors. NDEP did not evaluate new control measures for SO <sub>2</sub> and PM <sub>10</sub> at the Tracy Generating Station, as all units burn natural gas, resulting in low annual emissions for SO <sub>2</sub> and PM <sub>10</sub> . Additionally, to comply with BART during the first round of Regional Haze in Nevada, Unit 3 discontinued the occasional use of distillate fuel and was retrofitted with the best available Low-NO <sub>X</sub> Burners. These control measures are already incorporated into Nevada's SIP. A summary of the cost-effectiveness values for each technically feasible control technology considered at Tracy Unit 3 is provided in table 2.
| Control | Unit | Baseline emissions | Tons reduced | Total | Cost- |
| --- | --- | --- | --- | --- | --- |
| SNCR | Tracy Unit 3 | 138 tpy NO | 35 tpy NO | $474,641 | $13,561 |
| SCR | Tracy Unit 3 | 138 tpy NO | 124 tpy NO | 1,387,040 | 11,186 |
For Unit 3, NDEP identified SCR and SNCR as technically feasible NO <sub>X</sub> control measures. The four-factor analysis for Unit 3 used baseline emissions derived from the annual average of emissions observed from 2016 through 2020. NDEP estimated two to three years to fully implement SCR or SNCR at Unit 3. NDEP also factored in an annual electricity cost for SCR to account for increased electrical demand caused by a backpressure. NDEP relied on the remaining useful life of 20 years and 30 years, respectively, for SNCR and SCR. As shown in table 4, all potential control measures evaluated for Unit 3 yield a cost-effectiveness value above NDEP's threshold of $10,000 per ton of NO <sub>X</sub> reduced. [^82] Based on the four statutory factors, NDEP concluded that no new control measures for Tracy Unit 3 are necessary to make reasonable progress.
[^82] 2022 Nevada Regional Haze Plan, table 5-16.
For Unit 4 Piñon Pine, in the 2022 Nevada Regional Haze Plan NDEP relied on a closure date of December 31, 2031, as necessary to achieve reasonable progress. However, as explained in the 2025 SIP Supplement, changes in the energy landscape along with transmission system reliability considerations in Nevada necessitated reconsideration of the retirement of Tracy Unit 4 Piñon Pine by December 31, 2031. Similar to what was done for North Valmy Generating Station, NDEP withdrew the reasonable progress determination for Tracy Unit 4 Piñon Pine on July 27, 2023, and then submitted a new reasonable progress determination for this unit as part of the 2025 SIP Supplement. The EPA is not proposing to act on the revised reasonable progress determination for Tracy Unit 7 (Unit 4 Piñon Pine) in the 2025 SIP Supplement at this time.
Further, NDEP also determined that the existing NO <sub>X</sub> controls at Units 3, 5, 6, 7, 32, and 33 are necessary to make reasonable progress. The existing requirements for Unit 3 are already incorporated into the Nevada SIP as BART requirements. For the remaining existing controls, NDEP therefore submitted portions of Tracy Generating Station's permit, Permit No. AP4911-0194.04 for incorporation into the SIP. [^83] Table 3 summarizes the relevant permit conditions and controls, emissions limits, and associated requirements at Tracy Generating Station, which NDEP submitted for SIP approval. To make the new control measures enforceable, NDEP adopted and submitted emissions limitation and associated requirements as part of regulation R138-24.
[^83] See 2022 Nevada Regional Haze Plan, section 5.6.7 and appendix A.5. See also 2025 Supplement, appendix A.2.
| Tracy Generating Station, Permit No. AP4911-0194.04 | Citation | Permit condition |
| --- | --- | --- |
| | | |
| NO
: | | |
| IV.B.1.a | Emissions from S2.006 shall be controlled by Dry LNB while combusting natural gas only. Emissions from S2.006 shall be controlled with Water Injection while combusting No. 2 Distillate Fuel Oil under “Emergency” conditions defined in B.2.c. of this section. | |
| IV.B.3.f | The discharge of NO
(oxides of nitrogen) to the atmosphere shall not exceed: | |
| | (1) 9 parts per million by volume (ppmv) at 15 percent oxygen and on a dry basis, based on a 24-hour rolling period. | |
| | (2) 42.0 pounds per hour, based on a 720-hour rolling period. | |
| | (3) 122.64 tons per year, based on a 12-month rolling period. | |
| | | |
| NO
: | | |
| IV.D.1.a | Emissions from S2.007 shall be controlled by Dry LNB while combusting Pipeline Natural Gas only. Emissions from S2.006 shall be controlled with Water Injection while combusting No. 2 Distillate Fuel Oil under “Emergency” conditions defined in D.2.c. of this section. | |
| IV.D.3.f | The discharge of NO
(oxides of nitrogen) to the atmosphere shall not exceed: | |
| | (1) 9 parts per million by volume (ppmv) at 15 percent oxygen and on a dry basis, based on a 24-hour rolling period. | |
| | (2) 42.0 pounds per hour, based on a 720-hour rolling period. | |
| | (3) 122.64 tons per year, based on a 12-month rolling period. | |
| | | |
| NO
: | | |
| IV.F.1 | a. Emissions from S2.009 shall be controlled by a Steam Injection for control of NO
. | |
| | b. Emissions from S2.009.1 shall be controlled by Dry Low NO
Burners. | |
| | | |
| NO
: | | |
| IV.L.1.a | NO
emissions from S2.064 and S2.065 shall be controlled by SCR. The SCR shall utilize Ammonia Injection into the SCR at a volume specified by the manufacturer. | |
| IV.L.3.g | The discharge of NO
to the atmosphere shall not exceed 2.0 parts per million by volume (ppmv) at 15 percent oxygen on a dry basis, based on a 3-hour rolling period. | |
| | | |
| NO
: | | |
| IV.M.1.a | NO
emissions from S2.066 and S2.067 shall be controlled by SCR. The SCR shall utilize Ammonia Injection into the SCR at a volume specified by the manufacturer. | |
| IV.M.3.g | The discharge of NO
to the atmosphere shall not exceed 2.00 parts per million (ppmv) by volume at 15 percent oxygen and on a dry basis, per 3-hour rolling period. | |
| | | |
| V.A & V.C | NO
Continuous Emissions Monitoring System (CEMS) Conditions. | |
**c. Lhoist North America Apex Plant**
Lhoist North America Apex Plant is a lime production facility located in Clark County northeast of the Las Vegas metropolitan area. The plant includes four horizontal rotary preheater lime kilns, which are permitted to utilize coal, petroleum coke, and/or natural gas. [^84] The permitting authority for this facility is the Clark County Department of Environment and Sustainability (DES). NDEP derived the baseline emissions for the facility from the annual average of emissions reported from 2016 to 2018. The facility screened in with a Q/d value of 18.84, and the nearest Class I area is Grand Canyon National Park at 88 kilometers away. A summary of NDEP's cost-effectiveness analysis for the Apex Plant is provided in table 4.
[^84] 2022 Nevada Regional Haze Plan, section 5.7 and appendix B.1.
For NO <sub>X</sub> , NDEP identified LNB and SNCR as technically feasible control measures. Kilns 3 and 4 already implement LNB, so NDEP only evaluated LNB for Kilns 1 and 2. None of the kilns currently operate SNCR, so NDEP evaluated SNCR for all four kilns. For purposes of its analysis, NDEP assumed LNB would achieve a 10 percent NO <sub>X</sub> reduction, while SNCR would achieve a 20 percent NO <sub>X</sub> reduction at Kilns 1, 2, and 3, and a 50 percent NO <sub>X</sub> reduction at Kiln 4. [^85] NDEP also assumed 20 years for the remaining useful life of the units.
[^85] The control efficiency of SNCR differs between Kiln 4 and the rest of the Apex Plant kilns due to differences in age and configuration (discussed further in Lhoist's four-factor analysis). See 2022 Nevada Regional Haze Plan, Chapter 5.7.3.
For SO <sub>2</sub> , at Kilns 2 and 4, NDEP identified a switch to use of natural gas only as a technically feasible control measure. NDEP found that a fuel switch to use of natural gas was not feasible for Kilns 1 and 3 because these kilns are intended to produce dolomitic lime, which cannot be produced using 100 percent natural gas. NDEP also noted that, while switching to 100 percent natural gas at Kilns 2 and 4 would reduce SO <sub>2</sub> and PM <sub>10</sub> emissions, it would increase NO <sub>X</sub> emissions. Therefore, for its analysis of a fuel switch, NDEP calculated baseline emissions and tons reduced from the sum of NO <sub>X</sub> , SO <sub>2</sub> , and PM <sub>10</sub> emissions. NDEP also assumed an estimated control life of 20 years.
NDEP found that existing baghouses that meet the definition of best available control technology (BACT) at all four kilns constitute effective controls for PM <sub>10</sub> .
| Control | Kiln | Baseline emissions | Control | Tons reduced | Total | Cost- |
| --- | --- | --- | --- | --- | --- | --- |
| LNB | 1 | 304 tpy NO | 10 | 30.35 tpy NO | $25,792 | $850 |
| | 2 | 19 tpy NO | 10 | 1.91 tpy NO | 25,792 | 13,494 |
| SNCR | 1 | 304 tpy NO | 20 | 60.70 tpy NO | 164,394 | 2,708 |
| | 2 | 19 tpy NO | 20 | 3.82 tpy NO | 144,681 | 37,847 |
| | 3 | 154 tpy NO | 20 | 30.84 tpy NO | 154,044 | 4,995 |
| | 4 | 687 tpy NO | 50 | 343.34 tpy NO | 262,344 | 764 |
| Fuel Switch to 100% NG | 2 | 23.66 tpy NO
, SO
, and PM | 99.92 | 1.02 tpy NO
, SO
, and PM | 8,708,565 | 8,666,204 |
| | 4 | 724.46 tpy NO
, SO
, and PM | 99.62 | −147.92 tpy NO
, SO
, and PM | 1,589,821 | N/A |
Table 4 summarizes the cost-effectiveness analysis for the Apex Plant. Based on the four statutory factors, NDEP concluded that the implementation of LNB at Kiln 1, and the implementation of SNCR at Kilns 1, 3, and 4 are necessary to achieve reasonable progress during the second implementation period, as the cost-effectiveness values for these controls were below NDEP's threshold. LNB were recently installed on Kilns 3 and 4 and NDEP determined that the continued use of LNB on Kiln 3 and 4 is necessary to make reasonable progress as well. Accordingly, Clark County DES incorporated these new limits and other associated requirements into the Apex Plant's air quality operating permit, [^86] and NDEP submitted the relevant portions of the Apex Plant's permit, Authority to Construct (ATC) Permit, for a Major Part 70 Source, Source ID: 3, for SIP approval. [^87] Table 5 summarizes the relevant permit conditions for controls, emissions limits, and associated requirements at the Apex Plant for approval into the SIP. NDEP clarified in the 2025 SIP Supplement that Apex's ATC Permit expired 18 months after its original issue date of August 3, 2022, and was reissued by the Clark County DES on February 6, 2024. This permit was again renewed on April 30, 2025, and NDEP submitted the latest version of the permit in appendix A.1 of the 2025 SIP Supplement.
[^86] New NO <sub>X</sub> emission limits (and other requirements) that reflect the use LNB and SNCR at Kilns 1, 3, and 4, are found in appendix B.1.a of the 2022 Nevada Regional Haze Plan.
[^87] 2022 Nevada Regional Haze Plan appendix A.1. The Apex Plant is located in Clark County, so the permit for the facility is issued and enforced by the Clark County DES.
| Apex Plant, Authority to Construct Permit for a Major Part 70 Source, Source ID: 3, Clark County DES | Citation | Permit condition |
| --- | --- | --- |
| | | |
| NO
: | | |
| 2.2.1 | The control requirements and the NO
emission reductions proposed in the ATC are permanent and shall not be removed, changed, revised, or modified without the approval of NDEP and the EPA upon becoming effective. | |
| 2.2.2 | Effective no later than two years after the EPA's approval of the controls determination associated with the SIP, the permittee shall install and maintain low-NO
burners (LNB) on Kilns 1, 3 and 4 in order to achieve a reduction of NO
emissions (emission units (EUs): K102, K302, and K402). | |
| 2.2.3 | Effective no later than two years after the EPA's approval of the controls determination associated with the SIP, the permittee shall install, operate, and maintain selective non-catalytic reduction (SNCR) on Kilns 1, 3, and 4 (EUs: K102, K302, and K402) to achieve reduction of NO
emissions. | |
| | | |
| NO
: | | |
| 3.2.1 | Effective no later than two years after the EPA's approval of the control's determination associated with the SIP, the permittee shall limit total NO
emissions from all operating kilns to 3.75 tons per day based on a consecutive 30-day average (EUs: K102, K202, K302, and K402). | |
| 3.2.2 | Effective no later than two years after the EPA's approval of the control's determination associated with the SIP, the permittee shall limit the combined total NO
emissions from all operating kilns to 3.59 lb/tons of lime produced (tlp) based on a consecutive 12- month average (EUs: K102, K202, K302, and K402). | |
| | | |
| NO
: | | |
| 4.1 | Monitoring. | |
| 4.3 | Recordkeeping. | |
| 4.4.7, 4.4.8, 4.4.15, 4.4.16 | Reporting and Notifications. | |
**d. Graymont Pilot Peak Plant**
Graymont Pilot Peak Plant is a lime plant owned by Graymont Western US, Inc. that consists of three horizontal rotary preheater lime kilns. [^88] The three kilns use coal as a primary fuel source. Kilns 1, 2, and 3 are permitted for producing lime at a rate of 25, 33.3, and 50 tons per hour, respectively. The facility initially screened in with a Q/d value of 5.15, and the nearest Class I area is the Jarbidge Wilderness Area at 130 kilometers away. The emissions used were from the 2014 NEIv2. However, updated NO <sub>X</sub> emissions later resulted in a Q/d value of 4.61. [^89] Emissions for 2015-2018 also yielded Q/d values below 5. Emissions reported in 2019 and 2020 yielded Q/d values above 5, but NDEP cited several reasons for still screening out the facility, including the fact that using 2017 NEI data yields a Q/d of 3.66, and the overall average Q/d for the most recent seven years was below the threshold of 5. For these reasons, NDEP formally screened the facility out of a four-factor analysis requirement, but included information submitted for the facility's four-factor analysis in the Plan.
[^88] 2022 Nevada Regional Haze Plan, section 5.8 and appendix B.2.
[^89] 2022 Nevada Regional Haze Plan tables 5-27, 5-28, and 5-29. Graymont indicated that the emissions reported in the 2014 NEIv2, particularly the NO <sub>X</sub> emissions, did not agree with what was submitted by Graymont for Pilot Peak's 2014 Annual Emission Inventory (AEI). Graymont's AEI for Pilot Peak in 2014 resulted in a Total Q of 604 tons per year (tpy), rather than 673, resulting in a Q/d of 4.61. The AEI is calculated using the reporting requirements in the facility's air quality operating permit.
In addition, NDEP evaluated whether any existing measures at the facility were necessary to achieve reasonable progress. NDEP provided a weight-of-evidence demonstration for existing SO <sub>2</sub> and PM <sub>10</sub> control measures at the Pilot Peak Plant to determine that these controls are not necessary to make reasonable progress. NDEP indicated that historical and projected emissions rates for SO <sub>2</sub> and PM <sub>10</sub> remain low and consistent, making it reasonable to assume that the source will continue to implement its existing measures and will not increase its emissions rate. For the control of NO <sub>X</sub> emissions, Graymont Western has implemented LNB at all three of the Pilot Peak kilns in recent years. NDEP identified the continued use of existing LNB at all three kilns as necessary to make reasonable progress. Therefore, NDEP incorporated these new limits, and associated requirements into Pilot Peak's air quality operating permit and submitted the relevant portions of the permit as part of the 2022 Nevada Regional Haze Plan. NDEP issued a minor revision to this permit on June 14, 2024, and submitted the updated permit as part of the 2025 SIP Supplement. [^90] Table 6 summarizes the relevant permit conditions for controls, emissions limits, and associated requirements at Pilot Peak, which NDEP submitted for approval into the SIP in the 2025 SIP Supplement.
[^90] 2025 SIP Supplement, appendix A.3.
| Pilot Peak Plant, Permit No. AP3274-1329.03 | Citation | Permit condition |
| --- | --- | --- |
| | | |
| NO
: | | |
| IV.K.1.a | Emissions from S2.031 through S2.033 shall be controlled by a baghouse (D-85) and LNB. | |
| IV.K.3.b | The Permittee, within 240 days upon issuance of this operating permit, shall not discharge into the atmosphere from the exhaust stack of baghouse (D-85) the following pollutants in excess of the following specified limits: | |
| IV.K.4.q, IV.K.4.u | Specific Monitoring, Recordkeeping, and Reporting Requirements. | |
| V.B-C | NO
CEMS Requirements for System 10 (S2.031, S2.032, and S2.033), System 13 (S2.036, S2.037, S2.038), and System 17 (S2.042, S2.043, S2.044). | |
| | | |
| NO
: | | |
| IV.N.1.a | Emissions from S2.036 through S2.038 shall be controlled by a baghouse (D-285) and LNB. | |
| IV.N.3.b | The Permittee, within 240 days upon issuance of this operating permit, shall not discharge into the atmosphere from the exhaust stack of baghouse (D-285) the following pollutants in excess of the following specified limits: | |
| IV.N.4.q, IV.N.4.u | Specific Monitoring, Recordkeeping, and Reporting Requirements. | |
| V.B-C | NO
CEMS Requirements for System 10 (S2.031, S2.032, and S2.033), System 13 (S2.036, S2.037, S2.038), and System 17 (S2.042, S2.043, S2.044). | |
| | | |
| NO
: | | |
| IV.S.1.a | Emissions from S2.042 through S2.044 shall be controlled by a baghouse (D-385) and Low-NO
Burners. | |
| IV.S.3.b | The Permittee, within 240 days upon issuance of this operating permit, shall not discharge into the atmosphere from the exhaust stack of baghouse (D-385) the following pollutants in excess of the following specified limits: | |
| IV.S.4.q, IV.S.4.u | Specific Monitoring, Recordkeeping, and Reporting Requirements. | |
| V.B-C | NO
CEMS Requirements for System 10 (S2.031, S2.032, and S2.033), System 13 (S2.036, S2.037, S2.038), and System 17 (S2.042, S2.043, S2.044). | |
**e. Nevada Cement Company (NCC) Fernley Plant**
NCC Fernley Plant is a Portland cement manufacturing plant located in Fernley, Nevada, consisting of two coal-fired long-dry process kilns. [^91] The facility initially screened in with a Q/d value of 14.5, [^92] and the nearest Class I area is Desolation Wilderness at 102 kilometers away.
[^91] 2022 Nevada Regional Haze Plan, section 5.9 and appendix B.4.
[^92] Additional CEMS data yielded a Q/d value of 30.9 due to updated emissions of annual NO <sub>X</sub> and SO <sub>2</sub> . The new value does not change the source selection outcome for this facility.
The Fernley Plant is currently subject to an EPA Consent Decree to control NO <sub>X</sub> and SO <sub>2</sub> emissions. [^93] The Consent Decree requires that both kilns at the Fernley Plant emit no more than 1.1 pound of SO <sub>2</sub> per ton of clinker. To control NO <sub>X</sub> emissions, the facility is required to install SNCR. After the demonstration period, the consent decree requires the source to submit a demonstration report for each kiln's SNCR performance, and a final 30-day rolling average emission limit for NO <sub>X</sub> for both kilns is then derived from the findings of the demonstration report. The consent decree also requires the installation and continued use of Continuous Emission Monitoring Systems (CEMS) for both kilns to measure and monitor SO <sub>2</sub> and NO <sub>X</sub> emissions. The facility has since implemented CEMS for both kilns and relies on CEMS for SO <sub>2</sub> and NO <sub>X</sub> emissions reporting. NDEP stated that it is relying on the consent decree to screen the facility out of further consideration of potential new control measures, as the Consent Decree requires BACT-level controls for NO <sub>X</sub> , SO <sub>2</sub> , and PM <sub>10</sub> emissions. Once the EPA has approved all necessary limits through the process set forth in the CD, the CD requires these new limits to be incorporated into a federally enforceable permit issued under the Nevada SIP and then the facility's Title V permit. On this basis, NDEP concluded that the consent decree controls for NO <sub>X</sub> and SO <sub>2</sub> are not necessary to achieve reasonable progress.
[^93]*United States of America* v. *Nevada Cement Company,* Civil Action No. 3:17-cv-00302-MMD-WGC. Available at *https://www.justice.gov/enrd/consent-decree/file/1089586/download* and *https://www.justice.gov/enrd/consent-decree/file/1089596/download.*
Although the Fernley Plant was not required to conduct a four-factor analysis for potential new control measures, NDEP asked the facility to evaluate the continuous use of the facility's existing DSI system, as opposed to occasional use, considering the four statutory factors to achieve additional SO <sub>2</sub> emissions reductions. The analysis did not yield additional cost-effective controls. Considering the four statutory factors outlined above, Nevada determined that the upgrade of the existing DSI system to operate at full capacity for both kilns is not necessary to achieve reasonable progress.
Further, based on consistent historical emissions and PM <sub>10</sub> emissions limits listed in the Fernley Plant's permit, Permit No. AP3241-0387.02, NDEP also determined that the existing baghouses used to achieve current PM <sub>10</sub> emissions limits listed in the facility's air quality operating permit are not necessary to achieve reasonable progress. [^94]
[^94] 2022 Nevada Regional Haze Plan, table 5-36. Additionally, a demonstration with supporting documentation is included in the source's Control Determination in appendix B.
**5. Summary of Control Determinations**
In summary, in the 2022 Nevada Regional Haze Plan concluded that implementation of add-on controls at a lime production plant and the continued use of several existing controls are all necessary to achieve reasonable progress for the second planning period. NDEP submitted permits incorporating these measures and associated monitoring, recordkeeping, and reporting requirements in Appendix A of the 2025 SIP Supplement. NDEP's control measure determinations from the 2022 Nevada Regional Haze Plan, including specific permit conditions, are summarized in table 7 of this document. As previously noted, the EPA is not proposing to act on the revised reasonable progress determinations for Tracy Unit 7 (Piñon Pine Unit 4) and North Valmy Generating Station's Unit 1 and Unit 2, which were included in the 2025 SIP Supplement, at this time.
| Facility | Unit | Control | Pollutant | Existing or | Compliance deadline |
| --- | --- | --- | --- | --- | --- |
| Tracy | Unit 5 | Dry Low NO
Combustor | NO | Existing | Upon SIP approval. |
| | Unit 6 | Dry Low NO
Combustor | NO | Existing | Upon SIP approval. |
| | Unit 7 (Piñon Pine Unit 4 | Steam injection | NO | Existing | Upon SIP approval. |
| | Unit 32 | Dry Low NO
Combustor and SCR | NO | Existing | Upon SIP approval. |
| | Unit 33 | Dry Low NO
Combustor and SCR | NO | Existing | Upon SIP approval. |
| Lhoist North America Apex Plant | Kiln 1 | LNB | NO | New | No later than two years after SIP approval. |
| | Kiln 3 | LNB | NO | Existing | |
| | Kiln 4 | LNB | NO | Existing | |
| Graymont Pilot Peak Plant | Kiln 1 | LNB | NO | Existing | Within 240 days of operating permit issuance. |
| | Kiln 2 | LNB | NO | Existing | Within 240 days of operating permit issuance. |
| | Kiln 3 | LNB | NO | Existing | Within 240 days of operating permit issuance. |
**6. Additional Long-Term Strategy Requirements**
NDEP indicated in its submittal that the State consulted with other WRAP states in development of this SIP. [^95] Alaska, Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming agreed to work together to address regional haze in the western continental United States. The majority of state consultation in the development of the regional haze SIPs was conducted through the RHPWG. NDEP participated in the RHPWG, which took the products of the WRAP technical analysis and consultation process discussed above and developed a process for establishing RPGs in the western Class I areas.
[^95] 2022 Nevada Regional Haze Plan, section 9.1.3.
The WEP analysis conducted by the WRAP results shows the anthropogenic contributions at Jarbidge Wilderness Area. The point source contributions for nitrate come from industrialized portions of northern Nevada and along the Snake River Plain of Idaho, as well as more distant areas in southern Nevada and portions of California, including the Bay Area, Central Valley and Los Angeles area. [^96] The WEP analysis also show contributions from the main transportation corridors and population centers along I-80 in Nevada and Utah, I-84 in Utah, Idaho, and Oregon, and I-5 in California to NO <sub>X</sub> emissions at Jarbidge Wilderness Area. For sulfate, the point sources contributions come from the industrialized portions of northeastern Nevada and along the Snake River Plain of Idaho, as well as more distant areas in the Bay Area of California and Northwest Oregon. [^97] For primary organic aerosol and elemental carbon, Nevada has one point source contributing one to three percent of the respective component impacting extinction at Jarbidge Wilderness Area. [^98]
[^96] 2022 Nevada Regional Haze Plan, section 4.4.1.
[^97] Id. section 4.4.2.
[^98] Id. sections 4.4.3 and 4.4.4.
Aside from WRAP participation, NDEP engaged in direct state-to-state consultations with neighboring states and other states that are anticipated to impact visibility at Jarbidge, including: Arizona, California, Idaho, Oregon, Utah, Washington, and Wyoming. [^99] NDEP addressed the state consultation requirements of the rule and concluded that there are no disagreements between Nevada and any neighboring state. NDEP stated that it is not relying on reductions in another state to achieve reasonable progress at an in-state Class I area, and no neighboring states are relying on emissions reductions in Nevada to achieve reasonable progress in out-of-state Class I areas.
[^99] Confirmation of state-to-state consultations is provided in appendix E of the 2022 Nevada Regional Haze Plan.
In its submittal, NDEP also committed to continue consultation with Arizona, California, Idaho, Oregon and Utah, and any other state which may reasonably be anticipated to cause or contribute to visibility impairment at the Jarbidge Wilderness Area. [^100] NDEP will also continue consultation with any state for which Nevada's emissions may reasonably be anticipated to cause or contribute to visibility impairment in those states' Class I areas. NDEP also indicated that there were no disagreements between NDEP and any neighboring state with respect to regional haze commitments.
[^100] 2022 Nevada Regional Haze Plan, section 9.2.3.
The documentation requirement of 40 CFR 51.308(f)(2)(iii) provides that states may meet their obligations to document the technical bases on which they are relying to determine the emissions reductions measures that are necessary to make reasonable progress through an RPO, as long as the process has been “approved by all State participants.” As explained above, NDEP chose to rely on WRAP's technical information, modeling, and analysis to support development of its long-term strategy. The WRAP technical analyses on which NDEP relied are listed in the 2022 Nevada Regional Haze Plan and include source contribution assessments and visibility modeling information. NDEP further evaluated emissions reductions based upon the new control measures that the State evaluated as necessary for reasonable progress.
Section 51.308(f)(2)(iii) also requires that the emissions information considered to determine the measures that are necessary to make reasonable progress include information on emissions for the most recent year for which the state has submitted triennial emissions data to the EPA (or a more recent year), with a 12-month exemption period for newly submitted data. The 2022 Nevada Regional Haze Plan included 2014 NEI emission data [^101] for NO <sub>X</sub> , SO <sub>2</sub> , PM, VOCs and NH <sub>3</sub> and 2017 Air Markets Program Data (AMPD) emissions for NO <sub>X</sub> and SO <sub>2</sub> . NDEP also included 2017 NEI emissions data for comparison in its SIP submittal provided to confirm there are no significant differences between the emissions inventories developed and the most recent NEI to satisfy 40 CFR 51.308 (f)(2)(iii). NDEP's supplemental information included 2019 AMPD and 2017 NEI emission data for NO <sub>X</sub> (“2023 Nevada Regional Haze Technical Supplement”). [^102] NDEP also included an evaluation of NEI emissions from 2002 through 2017.
[^101] WRAP agreed to rely on the 2014 NEIv2 for source selection. This was done so that the Representative Baseline emission inventory (based on years 2014-2018) used in the SIP would agree with emissions used for source selection. At the time source selection was conducted, in August of 2019, the 2017 and 2020 NEI were not yet available. 2022 Nevada Regional Haze Plan, section 3.1.
[^102] Email dated July 31, 2023, from Steven McNeece, Nevada Division of Environmental Protection, to Khoi Nguyen, EPA Region IX. See also docket document “Progress Report Period (2013-2019) Emissions Analysis Supplement to the Nevada Regional Haze State Implementation plan for the Second Planning Period”.
Pursuant to § 51.308(f)(2)(iv)(A), NDEP noted in section 7.5 of its SIP submittal that existing and ongoing state and federal emissions control programs that contribute to emissions reductions through 2028 would impact emissions of visibility impairing pollutants from point and nonpoint sources in the second implementation period. NDEP included in its SIP comprehensive lists of control measures, pollutants addressed, and corresponding state regulations from the Nevada Administrative Code (NAC). [^103]
[^103] 2022 Nevada Regional Haze Plan, section 7.5.1.
NDEP's consideration of measures to mitigate the impacts of construction activities as required by § 51.308(f)(2)(iv)(B) includes, in section 7.6 of the 2022 Nevada Regional Haze Plan, a summary of measures that NDEP has implemented to mitigate the impacts from such activities. Nevada manages the release of fugitive dust from construction related activities through the implementation of regulations set forth in the NAC. NDEP has implemented standards that reduce fugitive dust emissions from construction, [^104] and requires an ongoing program, using best practical methods, to prevent particulate matter from becoming airborne. Additionally, a permit is required to disturb or cover five acres or more of land and a dust control plan is required for any disturbance greater than five acres for the Pahrump Valley in southern Nevada.
[^104] NAC 445B.22037.
Pursuant to § 51.308(f)(2)(iv)(C), source retirements and replacement schedules are addressed in section 7.7 of the 2022 Nevada Regional Haze Plan. Source retirements and replacements were considered in developing the 2028 emissions projections, with on-the-books/on the way retirements and replacements included in the 2028 projections. [^105] NDEP indicated that the State's continued implementation of NSR and PSD requirements with FLM involvement for Class I area impact review will protect the clearest days from further degradation and will assure that no Class I areas experience degradation from expansion or growth of a single new source or large-scale regional development of stationary sources.
[^105] The 2028OTBa2 emissions scenario in the WRAP modeling includes reductions due to “on-the-way” and “on-the-books” controls, consent decree reductions, SIP control measures, and other relevant regulations that have gone into effect since 2014 or will go into effect before the end of 2028.
In considering smoke management as required in 40 CFR 51.308(f)(2)(iv)(D), NDEP explained, in section 7.8 of the 2022 Nevada Regional Haze Plan, that it addresses smoke management through open burning regulations found in NAC 445B.22067. Open burn rules apply to federal, state, and private lands equally and prohibit open burning of combustible refuse, waste, garbage, oil or open burning for any salvage operation. Additionally, the Nevada Smoke Management Program [^106] was developed to coordinate and facilitate the statewide management of prescribed outdoor burning. This program is designed to meet the requirements of Nevada's air quality statutes administered by NDEP and compliance is achieved through a Memorandum of Understanding (MOU) between the various state and federal agencies that conduct prescribed burning, including the U.S. Bureau of Land Management, the U.S. Forest Service, the U.S. National Park Service, the U.S. Fish and Wildlife Service and Nevada state land management agencies. The signers of the MOU wrote a collaborative document, the Smoke Management Plan, [^107] which details the applicability of the program and responsibilities of affected parties, provides information on open burn authorization requirements for those land managers using prescribed fire and wildland fires for land management purposes, and includes information on air quality monitoring at prescribed fires, burner qualifications and emissions reduction methods.
[^106] The program meets Nevada's air quality statutes in Nevada Revised Statutes (NRS) 445B.100 through 445B.845. The program does not, however, supersede the authority of local governments to regulate and control smoke and air pollution under NRS 244.361 and NRS 268.410 or the authority of the state forester to regulate controlled fires under NRS 527.122 through 527.128.
[^107] Available at *https://ndep.nv.gov/uploads/air-pollutants-docs/smp-2013-final.pdf.*
NDEP considered the anticipated net effect of projected changes in emissions as required by § 51.308(f)(2)(iv)(E) by discussing, in section 7.9 of the 2022 Nevada Regional Haze Plan, the photochemical modeling for the period of 2014 through 2028. The two modeling cases run were a 2028 base case, which considered only on-the-books controls, and a 2028 control case that considered implementation of the known controls, such as the implementation of existing federal and state regulations, existing SIP control measures and other relevant regulations that have gone into effect since 2014 or will go into effect before the end of 2028. NDEP discussed that the final 2028 visibility projection for Jarbidge Wilderness Area during the 20 percent most impaired days is 7.76 dv. The difference between the second implementation period's baseline (7.97 dv) and RPG (7.76 dv), or anticipated visibility improvement, is 0.21 dv.
**7. Conclusion**
The EPA reviewed NDEP's four-factor analyses and determinations of controls necessary for reasonable progress in the 2022 Plan. As explained in section IV.E.2., NDEP relied on a Q/d threshold of five and 2014v2 emissions to select sources to undergo the four-factor analysis requirement. This analysis yielded eight point sources. NDEP further screened out three sources from the four-factor analysis requirement based upon prior shutdown of RGGS, emissions control beyond the scope of the State's authority for the McCarran International Airport, and existing BACT controls for TS Power Plant. The five remaining sources underwent NDEP's four-factor analysis and control determination process. We find that NDEP reasonably evaluated the sources that currently drive visibility impairment within the state, and that NDEP adequately explained and supported its decision to screen out three sources.
NDEP submitted numerous four-factor analyses and demonstrated that its determination of controls necessary for reasonable progress was based its consideration of the four statutory factors. Notably, NDEP's $10,000 cost per ton threshold is one of the highest cost thresholds established by any state for evaluating controls for the regional haze program. NDEP also evaluated whether existing control measures are necessary to make reasonable progress. Finally, the State incorporated the selected measures into enforceable permit conditions and submitted these for SIP approval. Accordingly, we are proposing to determine that the Plan satisfies the requirements of 40 CFR 51.308(f)(2)(i) and CAA section 169A(g)(1) to evaluate and determine the emissions reduction measures that are necessary to make reasonable progress by considering the four statutory factors.
We have also reviewed the Plan with respect to the remaining requirements of § 51.308(f)(2). As described in section IV.E.6., NDEP participated in the WRAP RHPWG and engaged in direct state-to-state consultations with other states. NDEP is not relying on any neighboring state's emissions reductions to achieve reasonable progress at its Class I area, Jarbidge Wilderness Area, and no neighboring states are relying on emissions reductions in Nevada to achieve reasonable progress in their state Class I areas. For these reasons, we propose to determine that NDEP has satisfied the consultation requirements of § 51.308(f)(2)(ii).
Based on the extensive documentation provided by the State of its analyses and supporting analyses conducted by the WRAP, we also propose to find that the Plan satisfies the requirements of 40 CFR 51.308(f)(2)(iii). We also propose to find that Nevada reasonably satisfied the requirements to consider the five additional factors of 40 CFR 51.308(f)(2)(iv) in developing its long-term strategy, as described in the section IV.E.6. Finally, we propose to find that NDEP has satisfied the requirement of § 51.308(f)(2) for the long-term strategy to “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)”, by submitting the relevant permit conditions and regulations for approval into the SIP.
Furthermore, we note that, it is now the EPA's policy that, where visibility conditions for a Class I Federal area impacted by a state are below the 2028 URP and the state has considered the four statutory factors, the state will have presumptively demonstrated reasonable progress for the second planning period for that area. [^108] In developing the regulations required by CAA section 169A(b), the EPA established the concept of the URP for each Class I area. The URP is determined by drawing a straight line from the measured 2000-2004 baseline conditions (in deciviews) for the 20 percent most impaired days at each Class I area to the estimated natural conditions (in deciviews) for the 20 percent most impaired days in 2064. From this calculation, a URP value can be calculated for each year between 2004 and 2064. The EPA developed the URP to address the diverse concerns of Eastern and Western states and account for the varying levels of visibility impairment in Class I areas around the country while ensuring an equitable approach nationwide. For each Class I area, states must calculate the URP for the end of each planning period ( *e.g.,* in 2028 for the second planning period). [^109] States may also adjust the URP to account for impacts from anthropogenic sources outside the United States and/or impacts from certain wildland prescribed fires. [^110] Then, for each Class I area, states must compare the reasonable progress goal (RPG) for the 20 percent most impaired days to the URP for the end of the planning period. If the RPG is above the URP, then an additional “robust demonstration” requirement is triggered for each state that contributes to that Class I area. [^111]
[^108] See, *e.g.,* 90 FR 29737, 29738 (July 7, 2025); 90 FR 20425, 20434 (May 14, 2025).
[^109] 40 CFR 51.308(f)(1)(vi)(A). We note that RPGs are a regulatory construct that we developed to address the statutory mandate in CAA section 169B(e)(1), which required our regulations to include “criteria for measuring `reasonable progress' toward the national goal.” Under 40 CFR 51.308(f)(3)(ii), RPGs measure the progress that is projected to be achieved by the control measures a state has determined are necessary to make reasonable progress. Consistent with the 1999 RHR, the RPGs are unenforceable, though they create a benchmark that allows for analytical comparisons to the URP and mid-implementation-period course corrections if necessary. 82 FR 3091-3092 (January 10, 2017).
[^110] 40 CFR 51.308(f)(1)(vi).
[^111] 40 CFR 51.308(f)(3)(ii).
Projected 2028 visibility conditions at Nevada's one Class I area and at other Class I areas identified by NDEP as being impacted by emissions from Nevada, are below the URP. There is one Class I area in a neighboring state, Sycamore Canyon in Arizona, where 2028 visibility conditions for the most impaired days are projected to be above the URP. [^112] However, Nevada did not identify Sycamore Canyon as being potentially affected by emissions from Nevada, based on WRAP source apportionment modeling. Moreover, the IMPROVE monitor for Sycamore Canyon was moved in 2015 (from SYCA1 to SYCA2), which creates uncertainty with respect to using data from the original monitor and the new monitor together to calculate visibility trends, and to comparing the 2028 model-projected Reasonable Progress Goal to the URP. As explained in the Arizona Regional Haze Plan, “a significant increase in soil and coarse mass extinction (two locally derived visibility impairing pollutants due to their limited transportability) occurred following the monitor's relocation.” [^113] Arizona further noted that:
[^112] Arizona Department of Environmental Quality, “State Implementation Plan Revision: Regional Haze Program (2018-2028)” (August 15, 2022) (“2022 Arizona Regional Haze Plan”), p. 102.
[^113] Id.
The impacts of monitor relocation on long-term trends of certain visibility impairing species such as coarse mass and soil (which are generally are more localized in impact due to their transportability) may call into question the representativeness of a monitor located outside of the Class I area, as is the case for SYCA_RHTS, when assessing Class I area visibility. This is especially true of the new SYCA2 IMPROVE monitoring site which is closely located to a small residential community and near dirt roads. [^114]
[^114] Id. at 105.
The EPA reviewed ADEQ's analyses and WRAP modeling regarding the Sycamore Canyon sites and conducted additional analyses of the monitoring data from the Sycamore Canyon and other monitoring sites in Arizona. These analyses show that there was a large increase in coarse mass and fine soil extinction after 2015 at SYCA2 that did not occur at other sites in Arizona. This divergence between SYCA2 and other monitors across the state indicates that the increase in coarse mass and fine soil extinction is likely due to local sources of coarse mass and fine soil at SYCA2 compared to SYCA1. Moreover, the increase was not consistent with modeled emissions changes in the WRAP multistate modeling domain and in Nevada occuring between 2014 and 2028, and not consistent with the transport of pollutants from Nevada. By contrast, the decreases in sulfate and nitrate extinction that were observed in the Sycamore Canyon monitoring through 2023, and that were predicted in the WRAP modeling of 2028, were consistent with emissions changes used in the modeling, and with greater progress in visibility than the glidepath. Data from the WRAP source apportionment modeling shows that in spite of recent observed increases in visibility impairment (primarily due to coarse mass and fine soil components), model-estimated US anthropogenic impairment is expected to be reduced by approximately 58 percent in 2028, compared to the 2000-2004 baseline. This is far more than the 40 percent reduction in impairment that would be required by the URP calculation between 2004 and 2028 to stay below the glidepath. Thus, given the modeled and monitored decrease in extinction from sulfate, nitrate, and organic matter, it is uncertain whether visibility impairment at Sycamore Canyon will be above the 2028 glidepath. Moreover, to the extent visibility impairment at Sycamore Canyon is above the 2028 glidepath, the available evidence indicates that this is due to local sources in Arizona, not Nevada. The EPA's analysis of impacts of Nevada's emissions on Sycamore Canyon is described in more detail in a memo included in the docket for this rulemaking action. [^115]
[^115] Memorandum September 4, 2025, from Scott Bohning, (EPA) to File/Rulemaking Docket EPA-R09-OAR-2025-0101, Subject: “Impact of Emissions from Nevada on Sycamore Canyon.”
Finally, we note that, while the EPA's policy establishes a presumption regarding areas that are projected to be *below* the URP, states whose emissions contribute to impairment in areas above the URP can still meet the applicable requirements of the CAA and the RHR. Indeed, the RHR specifically addresses this situation by requiring a “robust demonstration” that there are no additional emissions reduction measures at contributing sources that would be reasonable to include in the long-term strategy.” [^116] We address Nevada's compliance with this requirement in section IV.F. of this document.
[^116] 40 CFR 51.308(f)(3)(ii)(B).
In sum, Nevada selected a number of sources, evaluated emissions control measures, considered the four statutory factors, and determined that several existing and new controls were necessary to make reasonable progress. In addition, with the possible exception of Sycamore Canyon, all Class I areas in Nevada and neighboring states are at or below the glidepath. For the foregoing reasons, we propose to find that the Plan meets the requirements of 40 CFR 51.308(f)(2).
**F. Reasonable Progress Goals**
Section 51.308(f)(3) contains the requirements pertaining to RPGs for each Class I area. Because Nevada is host to a Class I area, it is subject to both § 51.308(f)(3)(i) and, potentially, to (ii). Section 51.308(f)(3)(i) requires a state in which a Class I area is located to establish RPGs—one each for the most impaired and clearest days—reflecting the visibility conditions that will be achieved at the end of the implementation period as a result of the emissions limitations, compliance schedules, and other measures required under paragraph (f)(2) to be in states' long-term strategies, as well as implementation of other CAA requirements. The long-term strategies as reflected by the RPGs must provide for an improvement in visibility on the most impaired days relative to the baseline period and ensure no degradation on the clearest days relative to the baseline period. 40 CFR 51.308(f)(3)(ii) applies in circumstances in which a Class I area's RPGs for the most impaired days represents a slower rate of visibility improvement than the uniform rate of progress calculated under 40 CFR 51.308(f)(1)(vi). Under 40 CFR 51.308(f)(3)(ii)(A), if the state in which a mandatory Class I area is located establishes an RPG for the most impaired days that provides for a slower rate of visibility improvement than the URP, the state must demonstrate that there are no additional emissions reduction measures for anthropogenic sources or groups of sources in the state that would be reasonable to include in its long-term strategy. Section 51.308(f)(3)(ii)(B) requires that if a state contains sources that are reasonably anticipated to contribute to visibility impairment in a Class I area in *another* state, and the RPG for the most impaired days in that Class I area is above the URP, the upwind state must provide the same demonstration.
NDEP's 2028 RPGs for the clearest and most impaired days at Jarbidge were set at 1.72 and 7.76 deciviews, respectively, in the 2022 Nevada Regional Haze Plan. [^117] These values were based on WRAP photochemical modeling results, with adjustments to account for updated emissions estimates by NDEP, and emissions reductions from controls in the State's long-term strategy, summarized in Chapter 6 table 6-1 of the 2022 Nevada Regional Haze Plan. Appendix H of the 2022 Regional Haze Plan details how the SO <sub>2</sub> and NO <sub>X</sub> emissions reductions were used to scale WRAP modeled extinction as used in the IMPROVE equation, then summed and converted to deciviews.
[^117] 2022 Nevada Regional Haze Plan, table 6-3.
NDEP incorporated the long-term strategy emissions controls in the RPG for the 20 percent most impaired days (MID) by scaling WRAP modeling results. [^118] NDEP first, for both SO <sub>2</sub> and NO <sub>X</sub> , calculated the ratio of the EGU emissions reduction at the North Valmy and Tracy plants, and the non-EGU emissions reduction at the Apex and Fernley Plants, to the respective EGU and non-EGU sector emissions that were used in WRAP visibility modeling for 2028. Second, NDEP used the calculated SO <sub>2</sub> and NO <sub>X</sub> ratios to scale the modeled average MID contribution of the respective sectors to ammonium sulfate and nitrate light extinction at the Jarbidge Wilderness Area on MID. (These contributions were available from the WRAP source apportionment modeling.) The resulting new total light extinction was then converted to deciviews that reflect the controls. This approach used average extinction over the MID days and then computed deciviews, Finally, to account for this difference in deciviews calculation order, NDEP applied a correction factor, the ratio of corresponding quantities available on the WRAP TSS website (deciviews from MID-average extinction, and MID-average deciviews). The result was the RPG for MID, an estimate of deciviews on most impaired days for 2028 that reflects the controls.
[^118] For all of the western Class I areas, the WRAP performed preliminary 2028 visibility projections and compared them to the 2028 URP using the 2028OTBa2 and PAC2 CAMx modeling results and the old and new IMPROVE equations. The 2028OTBa2 inventory included emission reductions due to known controls ( *i.e.,* implementation of existing federal and state regulations), existing SIP control measures and other relevant regulations that have gone into effect since 2014 or will go into effect before the end of 2028. Nevada quantified additional emission reductions achieved through reasonable progress controls and used them to determine the RPGs, using 2028OTBa2 as a foundation. We also note that Nevada indicated that the PAC2 WRAP modeling scenario included some potential measures from other WRAP states. However, Nevada did not use the projected 2028 visibility conditions at Jarbidge Wilderness Area from the PAC2 modeling scenario as RPGs.
For the 20 percent clearest days, NDEP used a slightly different scaling procedure, since only total extinction was available for sulfate and nitrate, not individual EGU and non-EGU extinction ( *i.e.,* source apportionment modeling was not done for the clearest days). For both sulfate and nitrate, NDEP assumed that controls would reduce the clearest day total extinction in the same proportion that it did for the most impaired days. NDEP took the resulting scaled extinctions and converted them to deciviews, and applied a correction factor, in the same way as it did for the MID. The result was the RPG for the clearest days, an estimate of deciviews on the clearest days for 2028 that reflects the controls included in the long-term strategy.
Although NDEP's RPGs in the 2022 Nevada Regional Haze Plan accounted for emissions associated with then-anticipated shutdown of North Valmy Generating Station Units 1 and 2, NDEP noted that the resulting changes to the RPGs were “lost in rounding (still 7.76 dv for most impaired days and 1.72 dv for clearest days).” [^119] Thus, regardless of the withdrawal of the enforceable shutdown of those units, NDEP's RPGs for Jarbidge of 7.76 deciviews for the most impaired days and 1.72 for the clearest days still reflect the visibility conditions that will be achieved at the end of the implementation period as a result of the NDEP's long-term strategy (as well as implementation of other CAA requirements) consistent with 40 CFR 51.308(f)(3)(i). The value of the adjusted URP in 2028 for the Jarbidge Wilderness Area is 8.2 deciviews. [^120] Nevada's RPG of 7.76 deciviews for the most impaired days is thus below the adjusted URP and the demonstration requirement under § 51.308(f)(3)(ii)(A) is not triggered. In addition, the RPG of 1.72 for the clearest days is below the 2000-2004 baseline visibility conditions of 2.56 deciviews on the 20 percent clearest days. Therefore, the long-term strategy and the RPGs provide for an improvement in visibility for the most impaired days since the baseline period and ensure no degradation in visibility for the clearest days since the baseline period consistent with 40 CFR 51.308(f)(3)(i).
[^119] 2022 Nevada Regional Haze Plan, p. 6-5.
[^120] 2022 Nevada Regional Haze Plan, section 6.9.3. The 2028 URP glide path value of 8.2 dv is interpolated between the baseline 2004-2004 value of 8.7 dv and the adjusted 2064 URP endpoint of 7.4 dv.
Under § 51.308(f)(3)(ii)(B), a state that contains sources that are reasonably anticipated to contribute to visibility impairment in a Class I area in another state for which a demonstration by the other state is required under § 51.308(f)(3)(ii)(B) must demonstrate that there are no additional emissions reduction measures that would be reasonable to include in its long-term strategy. NDEP explained in the Plan that the no neighboring states are relying on emissions reductions in Nevada to achieve reasonable progress in any of their Class I areas. In addition, NDEP conducted “URP Glidepath checks” for several out-of-state Class I areas that were specifically identified as being affected by emissions originating in Nevada (Grand Canyon, Arizona; Ike's Backbone, Arizona; Desolation Wilderness, California; Craters of the Moon, Idaho; Hells Canyon, Oregon; and Zion Canyon, Utah). [^121] NDEP confirmed that projected visibility in 2028 (2028OTBa2) for the 20 percent most impaired days for each area fall below the adjusted glidepath. [^122] In addition, as described in section IV.E.7. of this document, while the RPG for Sycamore Canyon in Arizona is above the adjusted glidepath, it is it reasonable to conclude that sources in Nevada are not the cause of this. Because Nevada did not determine that its sources contribute to impairment in Sycamore Canyon, it did not expressly make a robust demonstration under 40 CFR 51.308(f)(3)(ii)(B). However, as previously noted, NDEP submitted a robust long-term strategy, including numerous well-documented four-factor analyses and required new controls at multiple sources based on the outcome of these analyses. Accordingly, we find that there are no additional emissions reduction measures for anthropogenic sources or groups of sources in the State that may reasonably be anticipated to contribute to visibility impairment in the Class I area that would be reasonable to include in its own long-term strategy. Therefore, if a robust demonstration were required, the Plan would have met this requirement as well.
[^121] Id. section 6.9.4.
[^122] Id. For this analysis, NDEP employed adjustments for international emissions and prescribed fire determined by WRAP in accordance with EPA guidance, as described in section IV.D of this document.
For the foregoing reasons, the EPA proposes to determine that Nevada has satisfied the applicable requirements of 40 CFR 51.308(f)(3) relating to RPGs.
**G. Additional Monitoring To Assess Reasonably Attributable Visibility Impairment**
The EPA and FLMs have not previously advised Nevada that additional monitoring is needed to assess reasonably attributable visibility impairment. Therefore, the requirements under 40 CFR 51.308(f)(4) are not applicable to Nevada.
**H. Monitoring Strategy and Other Implementation Plan Requirements**
Section 51.308(f)(6) specifies that each comprehensive revision of a state's regional haze plan must contain or provide for certain elements, including monitoring strategies, emissions inventories, and any reporting, recordkeeping, and other measures needed to assess and report on visibility. A main requirement of this section is for states with Class I areas to submit monitoring strategies for measuring, characterizing, and reporting on visibility impairment. Compliance with this requirement may be met through participation in the IMPROVE network.
According to section 1.4.1.1 of the 2022 Nevada Regional Haze Plan, two operating IMPROVE monitoring sites are located in Nevada, one at Great Basin National Park and the other at the Jarbidge Wilderness Area. Additionally, the Walker River Paiute Tribe, a third monitoring site in Nevada, operated from June 2003 to November 2005. The IMPROVE monitor representing the air quality at the Jarbidge Wilderness Area is identified as JARB1 in the IMPROVE monitoring network database. Nevada indicates that generally, JARB1 is expected to be representative of aerosol characteristics in the Jarbidge Wilderness Area especially when the atmosphere is well mixed and regionally homogeneous. However, the site is at a low elevation in the Jarbidge River Canyon that is separate from the Jarbidge Wilderness Area and upper East Fork of the Jarbidge River. Consequently, the monitoring site may at times be isolated from wilderness locations and potentially impacted by different local emissions sources.
Section 51.308(f)(6)(i) requires SIPs to provide for the establishment of any additional monitoring sites or equipment needed to assess whether RPGs to address regional haze for all mandatory Class I Federal areas within the state are being achieved. JARB1 was among the first 20 IMPROVE sites to start operation in 1988 and is sponsored by the U.S. Forest Service. Nevada indicates in section 8.4 that the JARB1 IMPROVE site representing Nevada's Class I area at the Jarbidge Wilderness Area is considered to be sufficiently representative to support a determination of reasonable progress for the Jarbidge Wilderness Area.
Section 51.308(f)(6)(ii) requires SIPs to provide for procedures by which monitoring data and other information are used in determining the contribution of emissions from within the state to regional haze visibility impairment at mandatory Class I Federal areas both within and outside the state. The 2022 Nevada Regional Haze Plan indicates that generally, the WRAP has analyzed, deduced, and provided information on relative contributions to visibility impairment. Nevada also indicates that it has and will continue to use data reported by the IMPROVE program as input into the regional technical support analysis tool found at the Visibility Information Exchange Web System and WRAP's Technical Support System, as well as other analysis tools and efforts sponsored by the WRAP. Nevada will continue to participate in the regional analysis activities of the WRAP to collectively assess and verify the progress toward RPGs, as the RHR is implemented.
Section 51.308(f)(6)(iii) does not apply to Nevada, as it has a Class I area.
Section 51.308(f)(6)(iv) requires the SIP to provide for the reporting of all visibility monitoring data to the Administrator at least annually for each Class I area in the state. As noted above, the JARB1 IMPROVE monitor is located within the Jarbidge Wilderness Area and is operated and maintained by the U.S. Forest Service. The monitoring strategy for Nevada relies upon the continued availability of the IMPROVE network.
Section 51.308(f)(6)(v) requires SIPs to provide for a statewide inventory of emissions of pollutants that are reasonably anticipated to cause or contribute to visibility impairment, including emissions for the most recent year for which data are available and estimates of future projected emissions. It also requires a commitment to update the inventory periodically. Nevada indicates that it has prepared a statewide inventory of emissions that can reasonably be expected to cause or contribute to visibility impairment in mandatory Class I areas with the support of the WRAP. [^123]
[^123] 2022 Nevada Regional Haze Plan, chapter 3.
Section 51.308(f)(6)(v) also requires states to include estimates of future projected emissions and include a commitment to update the inventory periodically. Nevada also committed to updating its statewide emissions inventory periodically, and the updates will be used for state tracking of emission changes, determining trends and providing input into the WRAP's evaluation of whether RPGs are being achieved, as well as other regional analyses. Nevada will also depend upon and participate in additional periodic collective emissions inventory efforts by the WRAP.
The EPA proposes to find that Nevada has met the requirements of 40 CFR 51.308(f)(6) as described above, including through its continued participation in the IMPROVE network, continued inventory work with the WRAP, and commitment to update the inventory periodically, and that no further elements are necessary at this time for Nevada to assess and report on visibility pursuant to 40 CFR 51.308(f)(6)(vi).
**I. Requirements for Periodic Reports Describing Progress Towards the Reasonable Progress Goals**
40 CFR 51.308(f)(5) requires that periodic comprehensive revisions of states' regional haze plans also address the progress report requirements of 40 CFR 51.308(g)(1)-(5). The purpose of these requirements is to evaluate progress towards the applicable RPGs for each Class I area within the state and each Class I area outside the state that may be affected by emissions from within that state. Sections 51.308(g)(1) and (2) apply to all states and require a description of the status of implementation of all measures included in a state's first implementation period regional haze plan and a summary of the emissions reductions achieved through implementation of those measures. Section 51.308(g)(3) applies only to states with Class I areas within their borders and requires such states to assess current visibility conditions, changes in visibility relative to baseline (2000-2004) visibility conditions, and changes in visibility conditions relative to the period addressed in the first implementation period progress report. 40 CFR 51.308(g)(4) applies to all states and requires an analysis tracking changes in emissions of pollutants contributing to visibility impairment from all sources and sectors since the period addressed by the first implementation period progress report. This provision further specifies the year, or years, through which the analysis must extend depending on the type of source and the platform through which its emissions information is reported. Finally, 40 CFR 51.308(g)(5), which also applies to all states, requires an assessment of any significant changes in anthropogenic emissions within or outside the state have occurred since the period addressed by the first implementation period progress report, including whether such changes were anticipated and whether they have limited or impeded expected progress towards reducing emissions and improving visibility.
Section 51.308(f)(5) specifies that a progress report submitted as part of a comprehensive regional haze SIP revision must address the time period since the most recent progress report. Nevada submitted the most recent 5-year progress report to EPA in November 2014, which presented data analysis for the period 2008 through 2012 and 2018 RPGs. Therefore, for Nevada, the time period required to be addressed in the progress report under the second planning period SIP began in 2013.
The 2022 Nevada Regional Haze Plan also describes the status of measures of the long-term strategy from the first implementation period. [^124] During the first planning period for regional haze, programs that were put in place required control measures installed and operating by January 1, 2015, and focused on four sources, comprising 10 units—NV Energy's generating stations at Tracy (units 1, 2 and 3), Fort Churchill (units 1 and 2) and Reid Gardner (units 1, 2 and 3); and Southern California Edison's (SCE) Mohave Generating Station (units 1 and 2). Additionally, as mentioned in section IV.A., the EPA promulgated a FIP for RGGS in 2012 that was later rescinded in 2018 due to the shutdown of the facility. For Mohave Generating Station, Nevada describes that the facility was fully decommissioned and demolished and the operating permit for the facility was officially cancelled in April 2010. For NV Energy, Nevada describes that the Public Utilities Commission of Nevada granted approval for Tracy Units 1 and 2 to be retired, and approval to implement alternative equivalent control technology for BART and supplemental control technology for Unit 3 at Tracy and Units 1 and 2 at Fort Churchill. NV Energy retired Units 1 and 2 on December 31, 2014, and Nevada subsequently removed them from the Title V operating permit. Tracy Unit 3 discontinued the occasional use of distillate fuel and was retrofitted with the best available Low-NO <sub>X</sub> Burners before the compliance deadline. For Fort Churchill Units 1 and 2, the use of fuel oil has since been permanently suspended at the facility.
[^124] 2022 Nevada Regional Haze Plan, section 6.10.2.1.
The 2022 Nevada Regional Haze Plan also contains a summary of the emissions from the long-term strategy from the first implementation period, comparing emissions of NO <sub>X</sub> , SO <sub>2</sub> , and PM <sub>10</sub> at BART facilities for years 2008 and 2018. [^125] All BART sources show total emissions reductions, except for Mohave, which has emissions of 0 tpy for all pollutants in the analysis due to ceasing operations in 2005.
[^125] Id. section 6.10.2.2 and table 6-6.
The EPA proposes to find that Nevada has met the requirements of 40 CFR 51.308(g)(1) and (2) because the Plan describes the measures included in the long-term strategy from the first implementation period, as well as the status of their implementation and the emissions reductions achieved through such implementation.
The 2022 Nevada Regional Haze Plan included summaries of the visibility conditions and the trend of the 5-year averages through 2018 at the Jarbidge Wilderness Area. [^126] The Plan included the 5-year baseline (2000-2004) visibility conditions for the clearest and most impaired days of 2.56 and 8.73 deciviews, respectively. The status of the 2008-2012 period for the clearest and most impaired days are 1.84 and 7.88 deciviews, respectively. The Plan also included the current 5-year status (2014-2018) for the clearest and most impaired days of 1.84 and 7.97 deciviews, respectively. The EPA therefore proposes to find that Nevada has satisfied the requirements of 40 CFR 51.308(g)(3).
[^126] 2022 Nevada Regional Haze Plan, tables 2-1 and 2-2 and figures 2-4 and 2-5.
The 2022 Nevada Regional Haze Plan also addresses 40 CFR 51.308(g)(3)-(5). [^127] Specifically, chapter 2 addresses the requirements of 40 CFR 51.308 (g)(3), chapter 3 addresses the requirements of 40 CFR 51.308(g)(4), and chapter 4 addresses the requirements of 40 CFR 51.308(g)(5). In the 2023 Nevada Regional Haze Technical Supplement, NDEP also provided additional supporting information to address the requirements of 40 CFR 51.308(g)(4)-(5).
[^127] 2022 Nevada Regional Haze Plan, table 6-7.
Pursuant to § 51.308(g)(4), NDEP provided a summary of emissions of NO <sub>X</sub> , SO <sub>2</sub> , PM <sub>10</sub> , PM <sub>2.5</sub> , VOC, and NH <sub>3</sub> from all sources and activities, including from point, nonpoint, non-road mobile, and on-road mobile sources for the progress report period, for NEI years 2002, 2005, 2008, 2011, 2014, and 2017. NDEP also provided 2013-2019 Clean Air Markets Program Data (CAMPD) data for all sources with emissions of visibility impairing pollutants. The reductions achieved by Nevada emissions control measures are seen in the emissions inventory and visibility progress. The EPA is therefore proposing to find that Nevada has met the requirements of § 51.308(g)(4) by providing emissions information for NO <sub>X</sub> , SO <sub>2</sub> , PM <sub>10</sub> , PM <sub>2.5</sub> , VOC, and NH <sub>3</sub> broken down by type of sources and activities within the state.
Pursuant to § 51.308(g)(5), Nevada provided an assessment of any significant changes in anthropogenic emissions within or outside the state that have occurred since the period, including whether or not these changes in anthropogenic emissions were anticipated in that most recent plan, and whether they have limited or impeded progress in reducing pollutant emissions and improving visibility. NDEP noted overall reductions of 62 percent SO <sub>2</sub> , 5 percent PM <sub>10</sub> , 60 percent VOC, and 17 percent PM <sub>2.5</sub> when comparing 2014 with 2017 NEI data. NDEP noted emissions increases of 18 percent NO <sub>X</sub> , 68 percent NH <sub>3</sub> , and 17 percent PM <sub>2.5</sub> when comparing 2014 with 2017 NEI data. For these emissions increases, NDEP concluded that these increases are largely driven by increases in biogenic emissions. Nevada had a more intense wildfire season in 2017, where nearly 1.2 million acres were burned by wildfire, compared to roughly 80,000 acres burned in 2014. NDEP also noted increases in fertilizer application that affected NH <sub>3</sub> emissions and commercial cooking that affected PM <sub>2.5</sub> emissions. NDEP also noted that these increases have not limited or impeded visibility progress. NDEP further reported overall reductions of 34 percent NO <sub>X</sub> and 38 percent SO <sub>2</sub> in CAMPD EGU emissions during the progress report period. NDEP indicated that these reductions have met or exceeded the downward trend predicted from the regional haze plan in the first round. The EPA is therefore proposing to find that Nevada has met the requirements of § 51.308(g)(5).
**J. Requirements for State and Federal Land Manager Coordination**
CAA section 169A(d) requires states to consult with FLMs before holding the public hearing on a proposed regional haze SIP, and to include a summary of the FLMs' conclusions and recommendations in the notice to the public. In addition, 40 CFR 51.308(i)(2)'s FLM consultation provision requires a state to provide FLMs with an opportunity for consultation that is early enough in the state's policy analyses of its emissions reduction obligation so that information and recommendations provided by the FLMs can meaningfully inform the state's decisions on its long-term strategy. If the consultation has taken place at least 120 days before a public hearing or public comment period, the opportunity for consultation will be deemed early enough. Regardless, the opportunity for consultation must be provided at least sixty days before a public hearing or public comment period at the state level. 40 CFR 51.308(i)(2) also provides two substantive topics on which FLMs must be provided an opportunity to discuss with states: assessment of visibility impairment in any Class I area and recommendations on the development and implementation of strategies to address visibility impairment. 40 CFR 51.308(i)(3) requires states, in developing their implementation plans, to include a description of how they addressed FLMs' comments.
Sections 9.1 and 9.2 of the 2022 Nevada Regional Haze Plan describes the coordination and consultation with FLMs. Nevada indicates in section 9.1.1 that Nevada has provided agency contacts to the FLMs as required in 40 CFR 51.308(i)(1). The section also describes past coordination and consultation with FLMs during the development of the 2022 Nevada Regional Haze Plan in accordance with the provisions of § 51.308(i)(2). Numerous opportunities were provided by the WRAP for FLMs to participate in the development of technical documents developed by the WRAP, such as the opportunity to review and comment on analyses, reports, and policies, and opportunities for coordination and consultation with FLMs through tele-meetings and stakeholder outreach. The FLM consultation process included the opportunity to discuss their assessment of visibility impairment at the Jarbidge Wilderness Area and to provide recommendations on RPGs and the development and implementation of visibility control strategies.
Section 9.1.1.1 of the 2022 Nevada Regional Haze Plan describes the formal FLM consultation process. A draft version of the 2022 Nevada Regional Haze Plan was submitted to the FLMs [^128] on November 29, 2021, for a 60-day review and comment period. Comments were received from the National Parks Service and U.S. Forest Service on February 15, 2022. The U.S. Fish and Wildlife Service and Bureau of Land Management did not submit any comments as a result of the formal consultation period and expressed support for the contents of the draft SIP. As required by CAA 169A(d), Nevada indicates that the 2022 Nevada Regional Haze Plan also contained a summary of conclusions and recommendations of the FLMs as part of the SIP submission made available for public comment, along with a summary of how Nevada has addressed all comments and requests submitted by the FLMs, as required by 40 CFR 51.308(i)(3). NDEP's final response to comments received during the formal FLM consultation is provided in appendix C.
[^128] Nevada indicates that FLMs consist of the National Parks Service, U.S. Fish and Wildlife Service, U.S. Forest Service, and the Bureau of Land Management.
Section 9.2 of the 2022 Nevada Regional Haze Plan describes future coordination and consultation commitments. As required by 40 CFR 51.308(i)(4), Nevada indicates that it will continue to coordinate and consult with the FLMs during the development of future progress reports and plan revisions. The progress reports are to occur at five-year intervals, with the first report due five years from submittal of the initial RH SIP. Plan revisions are due every ten years, with the exception of the second SIP revision and subsequent progress report. The consultation process will provide on-going and timely opportunities to address the status of the control programs identified in this SIP, the development of future assessments of sources and impacts, and the development of additional control programs. Nevada will also provide the FLMs an opportunity to review and comment on future SIP revisions and the 5-year progress reports.
For the reasons stated above, the EPA proposes to find that Nevada has satisfied the requirements under 40 CFR 51.308(i) and CAA 169A(d) to consult with the FLMs on its regional haze SIP for the second implementation period and to include a summary of the FLMs' conclusions and recommendations in the notice to the public.
The 2022 Nevada Regional Haze Plan includes a commitment to submit a regional haze SIP revision by July 31, 2028, and every ten years thereafter in section 9.5. NDEP also committed to submit periodic progress reports in accordance with § 51.308(f) and evaluate progress towards the RPG for each mandatory Class I Federal area located within the state and in each mandatory Class I Federal area located outside the state that may be affected by emissions from within the state in accordance with § 51.308(g).
**V. Proposed Action**
The EPA is proposing to approve the Plan as satisfying the regional haze requirements for the second implementation period contained in 40 CFR 51.308(f). Specifically, we are proposing to approve the 2022 Nevada Regional Haze Plan (excluding the portions withdrawn on July 27, 2023) and appendix A of the 2025 SIP Supplement into the Nevada SIP. Thus, the EPA is proposing to approve and incorporate by reference in 40 CFR 52.1470(d) (“EPA-approved State source-specific permits”), the source-specific requirements listed below as part of Nevada's long-term strategy for regional haze, and as summarized in table 8 of this document.
• NDEP Permit No. AP4911-0194.04 (for Tracy Generating Station), Conditions IV.B.1.a, IV.B.3.f, IV.D.1.a, IV.D.3.f, IV.F.1, IV.L.1.a, IV.L.3.g, IV.M.1.a, IV.M.3.g, V.A, and V.C.
• Clark County DES Authority to Construct Permit for a Major Part 70 Source, Source ID: 3 (for Lhoist North America Apex Plant), Conditions 2.1.1, 2.2.1, 2.2.2, 2.2.3, 3.2.1, 3.2.2, 4.1, 4.3, 4.4.7, 4.4.8, 4.4.15, and 4.4.16.
• NDEP Permit No. AP3274-1329.03 (for Graymont Pilot Peak Plant), Conditions IV.K.1.a, IV.K.3.b, IV.K.4.q, IV.K.4.u, IV.N.1.a, IV.N.3.b, IV.N.4.q, IV.N.4.u, V.S.1.a, IV.S.3.b, IV.S.4.q, IV.S.4.u, and V.B-C.
| Name of source | Permit No. | State | Explanation |
| --- | --- | --- | --- |
| Lhoist North America Apex Plant | Clark County DES Authority to Construct Permit for a Major Part 70 Source, Source ID: 3 | April 30, 2025 | Permit conditions 2.1.1, 2.2.1, 2.2.2, 2.2.3, 3.2.1, 3.2.2, 4.1, 4.3, 4.4.7, 4.4.8, 4.4.15, and 4.4.16. |
| Graymont Pilot Peak Plant | NDEP Permit No. AP3274-1329.03 | June 14, 2024 | Permit conditions IV.K.1.a, IV.K.3.b, IV.K.4.q, IV.K.4.u, IV.N.1.a, IV.N.3.b, IV.N.4.q, IV.N.4.u, V.S.1.a, IV.S.3.b, IV.S.4.q, IV.S.4.u, and V.B-C. |
| Tracy Generating Station | NDEP Permit No. AP4911-0194.04 | March 23, 2022 | Permit conditions IV.B.1.a, IV.B.3.f, IV.D.1.a, IV.D.3.f, IV.F.1, IV.L.1.a, IV.L.3.g, IV.M.1.a, IV.M.3.g, V.A and V.C. |
**VI. Incorporation by Reference**
In this document, the EPA is proposing to include regulatory text in an EPA final rule that includes incorporation by reference. In accordance with requirements of 1 CFR 51.5, the EPA is proposing to incorporate by reference the regulatory and source-specific provisions described in section VI. of this preamble. The EPA has made, and will continue to make, these materials generally available through *https://www.regulations.gov* and at the EPA Region 9 Office (please contact the person identified in the *FOR FURTHER INFORMATION CONTACT* section of this preamble for more information).
**VII. Statutory and Executive Order Reviews**
Under the CAA, the Administrator is required to approve a SIP submission that complies with the provisions of the Act and applicable federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, the EPA's role is to approve state choices, provided that they meet the criteria of the Act. Accordingly, this proposed action merely proposes to approve state law as meeting federal requirements and does not impose additional requirements beyond those imposed by state law. For that reason, this proposed action:
• Is not a significant regulatory action subject to review by the Office of Management and Budget under Executive Order 12866 (58 FR 51735, October 4, 1993);
• Is not subject to Executive Order 14192 (90 FR 9065, February 6, 2025) because SIP actions are exempt from review under Executive Order 12866;
• 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 subject to Executive Order 13045 (62 FR 19885, April 23, 1997) because it proposes to approve a state program;
• Is not a significant regulatory action subject to Executive 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 the 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).
**List of Subjects in 40 CFR Part 52**
Environmental protection, Air pollution control, Incorporation by reference, Nitrogen dioxide, Ozone, Particulate matter, Sulfur oxides.
**Authority:**
42 U.S.C. 7401 *et seq.*
Dated: October 14, 2025.
Cheree D. Peterson,
Acting Regional Administrator, Region IX.