SUPPLEMENTARY INFORMATION:

Preamble acronyms and abbreviations. Throughout this preamble, the use of “we,” “us,” or “our” is intended to refer to the EPA. We use multiple acronyms and terms in this preamble. While this list may not be exhaustive, to ease the reading of this preamble and for reference purposes, the EPA defines the following terms and acronyms here:

BART Best Available Retrofit Technology

CAA Clean Air Act

CEMS Continuous Emissions Monitoring System

CBI Confidential Business Information

EPA Environmental Protection Agency

FIP Federal Implementation Plan

Keetac Keetac Taconite Facility in Keewatin, Minnesota

LNB Low-NO_X Burner

NESHAP National Emission Standards for Hazardous Air Pollutants

NO_X  Nitrogen Oxide

PBI Proprietary Business Information

PRA Paperwork Reduction Act

RFA Regulatory Flexibility Act

SCR Selective Catalytic Reduction

SIP State Implementation Plan

SO₂  Sulfur Dioxide

UMRA Unfunded Mandates Reform Act

U.S. Steel United States Steel

Organization of this document. The information presented in this preamble is organized as follows:

I. Background

II. Legal Authority

III. What Action is the EPA Taking?

IV. Public Comments and Responses

V. Statutory and Executive Order Reviews

Background

On February 6, 2013, the EPA promulgated a Federal Implementation Plan (FIP) that included NO_X BART limits for indurating furnaces at seven taconite facilities subject to BART in Minnesota and Michigan (the Original 2013 FIP Rule).^[1] The Original 2013 FIP Rule included NO_X BART limits for indurating furnaces at two U.S. Steel taconite facilities located in Minnesota—Keetac and Minntac. The EPA took this action following a January 15, 2009, determination that Minnesota and Michigan failed to timely submit regional haze SIPs.^[2] This finding triggered a CAA obligation that the EPA issue a FIP, which the Agency did on February 6, 2013. The Original 2013 FIP Rule, among other requirements, established NO_X BART emission limits of 1.2 MMBtu when burning natural gas and 1.5 lbs NO_X /MMBtu when using any fuel other than exclusively natural gas for Keetac's indurating furnace (along with indurating furnaces at six other taconite facilities in Michigan and Minnesota). These emission limits were based upon the observed performance of high stoichiometric (high-stoich) low-NO_X burners (LNBs) that were previously installed on taconite furnaces at Minntac.

Subsequent engineering studies demonstrated that the initial LNB design selection for Keetac, which was based on LNB operation at U.S. Steel's Minntac facility, would be infeasible at Keetac due to several technical factors. Further studies demonstrated that a different LNB main burner design, in combination with low-NO_X preheat burners, would be the most effective LNB design for Keetac in that the design represents the highest technically feasible emission reductions for this facility based on those studies.

On April 24, 2025, the EPA proposed to modify the NO_X BART emission limits for the indurating furnace at Keetac to reflect the degree of reduction achievable based on operations and parameters specific to the Keetac facility (the 2025 Proposed Rule).^[3] Specifically, the EPA proposed to approve the following NO_X BART emission limits for the Keetac Grate Kiln indurating furnace, with compliance to be determined on a rolling 720-hour average: (1) 3.4 lbs NO_X /MMBtu when firing exclusively natural gas, which will become enforceable beginning three years after promulgation of a final rule; and (2) 2.0 lbs NO_X /MMBtu when firing any fuel or combination of fuels other than exclusively natural gas, which will become enforceable five years after promulgation of a final rule, unless before that date the EPA promulgates a modified limit in accordance with the following procedure. The EPA proposed to allow Keetac, within a period of 52 months from the effective date of the final rule, the option to seek a potential adjustment of the cofiring emission limit, not to exceed 2.5 lbs NO_X /MMBtu as a 720-hour rolling average, based on collection of continuous emissions monitoring system (CEMS) data after installation of the NO_X reduction technology. Additional explanation of the CAA requirements, a detailed analysis of how these requirements apply to taconite facilities, and the EPA's reasons for proposing the revised limits are provided in the 2025 Proposed Rule.

Legal Authority

In the CAA Amendments of 1977, Congress created a program for ( printed page 34576) protecting visibility in the nation's national parks and wilderness areas. Section 169A of 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.” Congress added section 169B to the CAA in 1990 to address regional haze issues. EPA promulgated a rule to address regional haze on July 1, 1999 (64 FR 35714), codified at 40 CFR part 51, subpart P—Protection of Visibility (herein after referred to as the “Regional Haze Rule”). The Regional Haze Rule codified and clarified the BART provisions in the CAA at 40 CFR 51.308(e) and revised the existing visibility regulations to add provisions addressing regional haze impairment and establishing a comprehensive visibility protection program for Class I areas.

Section 169A of the CAA directs states, or EPA if developing a Federal Implementation Plan (FIP), to evaluate the use of retrofit controls at certain larger, often uncontrolled, older stationary sources to address visibility impacts from these sources. Specifically, section 169A(b)(2)(A) of the CAA requires that implementation plans contain such measures as may be necessary to make reasonable progress toward the natural visibility goal, including a requirement that certain categories of existing major stationary sources ^[4] built between 1962 and 1977 procure, install, and operate BART ^[5] as determined by EPA.

Under the Regional Haze Rule, states (or in the case of a FIP, EPA) are directed to conduct BART determinations for such “BART-eligible” sources that may reasonably be anticipated to cause or contribute to any visibility impairment in a Class I area.

On July 6, 2005, (70 FR 39104), EPA published the Guidelines for BART Determinations Under the Regional Haze Rule at appendix Y to 40 CFR part 51 (hereinafter referred to as the “BART Guidelines”), to assist states and EPA in determining which sources should be subject to the BART requirements and in determining appropriate emission limits for each source subject to BART.

The process of establishing BART emission limitations follows three steps. First, states, or EPA if developing a FIP, must identify and list “BART-eligible sources.” ^[6] Once the state or EPA has identified the BART-eligible sources, the second step is to identify those sources that may “emit any air pollutant which may reasonably be anticipated to cause or contribute to any impairment of visibility” in a Class I area. (Under the Regional Haze Rule, a source that fits this description is “subject to BART.”). Third, for each source subject to BART, the state or EPA must identify the level of control representing BART after considering the five factors set forth in CAA section 169A(g). The BART Guidelines provide a process for making BART determinations that states can use in implementing the BART requirements on a source-by-source basis. See40 CFR part 51, appendix Y, at IV.D.^[7]

States, or EPA if developing a FIP, must address all visibility-impairing pollutants emitted by a source in the BART determination process. The most significant visibility impairing pollutants are sulfur dioxide (SO₂), NO_X, and particulate matter (PM).

A State Implementation Plan (SIP) or FIP addressing regional haze must include source-specific BART emission limits and compliance schedules for each source subject to BART. Once a state or EPA has made a BART determination, the BART controls must be installed and operated as expeditiously as practicable, but no later than five years after the date of the final SIP or FIP. See CAA section 169A(g)(4) and 40 CFR 51.308(e)(1)(iv). In addition to what is required by the Regional Haze Rule, general SIP requirements mandate that the SIP or FIP include all regulatory requirements related to monitoring, recordkeeping, and reporting for the BART controls on the source. See CAA section 110(a).

What action is the EPA taking?

The EPA is finalizing modifications to the Original 2013 FIP Rule by changing the NO_X BART emission limits for the indurating furnace at Keetac. Specifically, the EPA is finalizing the following NO_X BART emission limits for the Keetac Grate Kiln indurating furnace, with compliance to be determined on a rolling 720-hour average: (1) 3.4 lbs NO_X /MMBtu when firing exclusively natural gas, which will become enforceable beginning three years after promulgation of a final rule; and (2) 2.0 lbs NO_X /MMBtu when firing any fuel or combination of fuels other than exclusively natural gas, which will become enforceable five years after promulgation of a final rule, unless before that date the EPA promulgates a modified limit. The final rule allows Keetac, within a period of 52 months from the effective date of the final rule, the option to seek a potential adjustment of the cofiring emission limit, not to exceed 2.5 lbs NO_X /MMBtu as a 720-hour rolling average, based on collection of CEMS data after installation of the NO_X reduction technology.

Public Comments and Responses

The EPA received no requests for a public hearing; therefore, no public hearing was held. The comment period on the 2025 Proposed Rule closed on June 10, 2025. The EPA received two comments on the Keetac proposal. One comment letter was submitted from the National Parks Conservation Association, Coalition to Protect America's National Parks, Minnesota Center for Environmental Advocacy, and Sierra Club (collectively, the Conservation Groups). The second comment was submitted anonymously. These comments are summarized and addressed below. One additional comment was received but did not contain comments related to the Keetac proposal.

Comment: The Conservation Groups assert that the EPA proposes to rubber stamp Keetac's data without conducting the BART analyses required under the CAA and Regional Haze Rule (RHR).^[8] The Conservation Groups further assert that the EPA improperly focuses only on the CEMS data provided by Keetac.

Response: The EPA disagrees with the Conservation Groups' assertions that the EPA proposed emission limits for Keetac without conducting a BART analysis as set forth in the CAA and RHR. Under the RHR, each State (or in the case of a FIP, the EPA), is directed to conduct BART determinations for such “BART-eligible” sources that may reasonably be anticipated to cause or contribute to any visibility impairment in a Class I area.^[9]

( printed page 34577)

In the August 15, 2012 Proposed FIP, the EPA conducted a five-factor BART analysis for the Keetac facility.^[10] The EPA conducted this five-factor analysis consistent with the BART Guidelines. In the Original 2013 FIP Rule, the EPA determined that LNB technology is BART for the Keetac facility and established NO_X BART emission limits based upon the performance of a specific LNB design that was installed on taconite furnaces at U.S. Steel's Minntac taconite facility. LNBs are widely used control devices proven to be effective at reducing NO_X from furnaces across many industrial sectors and the EPA has not changed the Agency's determination that LNBs are the appropriate BART control for Keetac. As discussed in the 2025 Proposed Rule, although the EPA based the initial LNB design selection for Keetac on LNB operation at U.S. Steel's Minntac facility, subsequent modeling demonstrated that, due to several technical factors, the Minntac LNB design would be infeasible at Keetac.^[11] Subsequent studies instead determined that a different LNB main burner design, in combination with low-NO_X preheat burners, would be feasible at Keetac and represented the most effective LNB design, offering the highest technically feasible emission reductions for this facility.^[12]

Comment: The Conservation Groups contend that it is unreasonable for the EPA to propose to relax the emission limits for NO_X from the furnace at the Keetac facility to allow more pollution.

Response: The EPA disagrees with the Conservation Groups' assertions regarding the EPA's actions. Of note, Keetac has not yet installed the identified NO_X controls; therefore, installation of any NO_X controls—including those proposed here—would result in NO_X reductions compared to what the Keetac facility is currently emitting. Therefore, compared to the current and recent emissions at Keetac, the final rule does not allow “more pollution.”

The RHR requires States (or in the case of a FIP, the EPA) to develop an implementation plan that sets emission limits based on the degree of reduction achievable through the application of the best system of continuous emission reduction.^[13] As noted in this section and as discussed in the 2025 Proposed Rule, the EPA conducted a five-factor BART analysis in the Original 2013 FIP and determined that LNB technology is BART for the Keetac facility. The EPA based the initial LNB design selection for Keetac on LNB operation at U.S. Steel's Minntac facility, but subsequent modeling demonstrated that, due to several technical factors, the Minntac LNB design would be infeasible at Keetac. Subsequent studies instead determined that a different LNB main burner design, in combination with low-NO_X preheat burners, would be the most effective LNB design for Keetac, offering the highest technically feasible emission reductions for this facility. The BART limits proposed for Keetac reflect the degree of reduction achievable based on the feasible LNB technology applied to operations and parameters specific to the Keetac facility.

Comment: The Conservation Groups contend that the EPA cannot merely rely on only the engineering studies and data to ensure reasonable progress toward natural visibility conditions.

Response: The EPA disagrees with the Conservation Groups' assertion that the Agency is relying on engineering studies and data to ensure reasonable progress. In this action, the EPA is promulgating NO_X BART emission limits for Keetac in accordance with the BART determination set forth in the Original 2013 FIP Rule and refined in the 2025 Proposed Rule for Keetac. The EPA is not promulgating a long-term strategy or establishing reasonable progress goals for Minnesota. On June 12, 2012, the EPA approved Minnesota's regional haze plan for the first implementation planning period as satisfying the applicable requirements in 40 CFR 51.308, except for BART emission limits for the taconite facilities.^[14] Among the regional haze plan elements approved were Minnesota's long-term strategy for making reasonable progress toward visibility goals. Minnesota's long-term strategy did not rely on the achievement of any particular degree of emission control from the taconite facilities, including Keetac, to achieve reasonable progress goals.

Comment: The Conservation Groups contend that the EPA's proposed action did not mention that the Agency already proposed revising the Keetac emission limits in a prior proposed rulemaking. The Conservation Groups claim that EPA must clarify the relationship between the Agency's prior proposal and this one.

Response: The EPA disagrees with the Conservation Groups' assertion that the EPA previously proposed to revise the NO_X emission limits for Keetac. Rather, on December 4, 2024, the EPA proposed a rule which set forth reporting and recordkeeping requirements that apply to all facilities subject to the Original 2013 FIP Rule and the Revised 2016 FIP Rule, including Keetac.^[15] Specifically, the EPA proposed to require facilities subject to the Original 2013 FIP Rule and the Revised 2016 FIP Rule, including Keetac, to submit reports electronically and allow sources to supplement emission data if the CEMS do not capture all data ( e.g., during startup, shutdown, and malfunction (SSM) conditions). The EPA did not propose emission limits for Keetac in the December 4, 2024, proposed rule.

Comment: The Conservation Groups assert that the EPA failed to require that Keetac optimize its emission control system. The Conservation Groups contend that the EPA must require that U.S. Steel optimize the emission control system to meet the efficiencies that the Agency identified as achievable. The Conservation Groups further contend that there is no evidence that the “variety of manufacturers and engineering firms” that U.S. Steel contracted with to “evaluate different NO_X reduction technologies” conducted their work independently and that it appears the manufacturers and engineering firms performed their work at the direction of U.S. Steel. The Conservation Groups suggest that this raises concerns about biased results that did not fully consider optimization.

Response: The EPA disagrees that the Agency must require Keetac to optimize its emission control system. The Original 2013 FIP Rule did not require that an affected taconite facility optimize its emission control system; instead, it established limits based on expected performance of the control technology. The proposed emission limits reflect the degree of reduction achievable based on operation and design parameters specific to the Keetac facility as specified in the engineering reports.^[16] In addition, taconite facilities are subject to the National Emission Standards for Hazardous Air Pollutants (NESHAP) at 40 CFR 63, subpart RRRRR. As required by the general provisions in the NESHAP, all affected taconite facilities are subject to a ( printed page 34578) “general duty” clause at 40 CFR 63.6(e) that requires all affected facilities to “at all times, including periods of startup, shutdown, and malfunction, operate and maintain any affected source, including associated air pollution control equipment and monitoring equipment, in a manner consistent with safety and good air pollution control practices for minimizing emissions.”

The EPA also disagrees with the Conservation Groups' contention that the fact that the engineering firms performed their assessments at the direction of U.S. Steel raises concerns about biased results. Third-party engineering studies are common practice for facilities seeking solutions to engineering challenges. Performing work on behalf of U.S. Steel does not render the work product biased. As stated in the 2025 Proposed Rule, Keetac's pellet production is double that of Minntac's, which affects the magnitude of fuel input, number and design of combustion fans required, and burner system components needed to successfully operate a burner. Therefore, Keetac required additional evaluation to ensure the proposed solutions would work at this facility. After reviewing, the EPA found no reason to disagree with the engineering studies.

Comment: The Conservation Groups assert that the EPA does not have the authority to ignore a clear statutory command to require BART in the implementation plan merely by revising emission limits. Moreover, the Conservation Groups claim that the EPA has never codified that BART is determined at one time, and that courts will not uphold an EPA action on a rationale that the Agency has never explained.

Response: The EPA disagrees with the Conservation Groups' assertion that the Agency ignored the statutory obligation to require BART. As discussed within this section, the EPA's BART determination for Keetac was finalized in the Original 2013 FIP Rule. The EPA further disagrees that this action requires a new BART analysis. BART was an explicit first implementation period requirement and, as part of the first implementation period, the EPA's BART determination for Keetac was finalized in the Original 2013 FIP Rule. Therefore, there is no requirement to re-evaluate BART controls for Keetac.

Comment: The Conservation Groups contend that the EPA failed to articulate the Agency's rationale for determining that the prior BART determination for Keetac still serves as a valid BART determination. The Conservation Groups claim that the CAA makes clear that BART is a mandatory part of “each applicable implementation plan,” and expressly requires that States (or in the case of a FIP, the EPA) “includ[e]” BART for “each” eligible source.

Response: The EPA disagrees with the Conservation Groups' contention that the Agency failed to articulate the Agency's rationale for maintaining the prior BART determination as the current, valid BART determination for this action. The EPA further disagrees that the CAA requires that BART must be reevaluated in every regional haze SIP revision. BART was an explicit first implementation period requirement and, as part of the first implementation period, the EPA's BART determination for Keetac was finalized in the Original 2013 FIP Rule.

CAA section 169A(b)(2)(A) requires “each applicable implementation plan” to include requirements to install and operate BART. While the CAA does not define the applicable implementation plans, the RHR does. Under the RHR at 40 CFR 51.308(d), “States were required to submit SIPs addressing regional haze visibility impairment in 2007, which covered what we refer to as the first implementation period (2008-2018).” ^[17] For subsequent implementation periods under 40 CFR 51.308(f), “[e]ach State identified in § 51.300(b) must revise and submit its regional haze implementation plan revision to the EPA by July 31, 2021, July 31, 2028, and every 10 years thereafter.” ^[18]

In the 2017 RHR, the EPA noted “States were required to undertake the BART determination process during the first implementation period. The BART requirement was a one-time requirement . . . .” ^[19] Therefore, while CAA section 169A(b)(2)(A) requires “each applicable implementation plan” to include requirements to go through the BART determination process, the RHR establishes the various implementation plan revisions under 40 CFR 51.308(b) and (f) and only requires undergoing the BART determination process in the first implementation plan revision under 40 CFR 51.308(e). The EPA finalized the Agency's BART determination for Keetac in the Original 2013 FIP Rule, as part of the first implementation period, and need not reevaluate BART controls for Keetac. Therefore, there is no requirement to re-evaluate BART controls for Keetac.

Comment: The Conservation Groups contend that the EPA failed to evaluate BART for Keetac to ensure that the proposed emission limitation revisions satisfy BART factors. The Conservation Groups assert that, to conduct compliant BART analyses for Keetac, the EPA should have considered the available control train that the Conservation Groups discuss in their 2024 Minnesota comments, which likely would result in lower emissions limits than included in the “taconite FIP” as necessary to make reasonable progress. The Conservation Groups contend that the EPA's proposed emission limitation revisions fail to meet the regulatory or statutory test for BART.

Response: The EPA disagrees with the Conservation Groups' assertion that the EPA failed to evaluate BART for Keetac. The EPA further disagrees that the Conservation Groups' September 11, 2024 comments on the Agency's proposed approval of Minnesota's Second Period Regional Haze SIP revision are relevant to this action. First, as described in this section, BART is a one-time requirement of the first planning period, per the CAA, and the EPA determined BART for Keetac in the Original 2013 FIP Rule.^[20] Second, the Keetac BART determination does not preclude Minnesota from having considered other control options to meet progress goals for the second planning period or beyond. Third, the EPA proposed approval of Minnesota's Second Period Regional Haze SIP revision on July 11, 2024. However, the EPA has not taken final action on the SIP revision. The EPA will respond to comments submitted on the Second Period SIP revision when taking final action on the SIP.

Comment: The Conservation Groups assert the EPA must address their numerous significant comments on this taconite source and the National Park Service's Federal Land Managers consultation comments on available controls for the taconite sources. These comments were submitted in response ( printed page 34579) to the EPA's proposed approval of Minnesota's Second Planning Period SIP revision.

Response: The EPA disagrees with the Conservation Groups' assertion as described in this section. Additionally, the EPA has not taken final action on Minnesota's Second Planning Period SIP revision. The EPA will respond to comments submitted on the Second Period SIP revision, including issues with respect to Federal Land Manager consultation, when taking final action on that plan.

Comment: The Conservation Groups note that the EPA specifically directed Minnesota to reconsider selective catalytic reduction (SCR) with reheat as an available control option for taconite facilities and contend that the Agency must evaluate this technology as BART for this action.

Response: In 2016, the EPA stated “We expect Minnesota and Michigan to reevaluate SCR with reheat as a potential option for making reasonable progress in future planning periods, but reject the technology as BART for the Minnesota and Michigan taconite facilities at this time.” ^[21] Thus, the EPA disagrees with the Conservation Groups' assertion that the Agency must reconsider SCR with reheat as an available BART control option for this action. As stated above, BART is a one-time requirement of the first planning period. However, this BART determination does not preclude Minnesota from reconsidering other control options, including SCR with reheat, to meet progress goals for the second planning period or beyond.

Comment: The Conservation Groups assert that the EPA wrongfully withholds and redacts information from the public, thwarting meaningful public participation, by withholding unspecified Fives North American Combustion (FivesNA) information regarding anticipated NO_X performance derived from unspecified laboratory testing and field installations, which contains redactions, and a February 24, 2016, technical memorandum developed by Barr, “Air Quality Regulatory Analysis for Low NO_X Burner Technology” labeled “U.S. Steel Confidential Settlement Agreement Communication Subject to FRE [Federal Rule of Evidence] 408,” which contains redactions. The Conservation Groups also contend the EPA proposes revising the BART emission limitations based on the redacted (withheld) information, without describing or providing a basis for withholding the information, merely noting in the footnotes that the documents are redacted.

The Conservation Groups assert that the information submitted by FivesNA merely mentions the laboratory testing and field installation studies and the EPA failed to include the detailed testing information and studies in the proposed docket and that there is nothing to indicate that the Agency received the underlying information and reviewed and confirmed FivesNA's assertions. The Conservation Groups contend that without the underlying information in the docket to support the assertions, the public cannot review and comment on the accuracy of the claims made.

Response: The EPA disagrees with the Conservation Groups' assertion that the Agency is modifying the BART emission limits based on redacted or withheld information. The docket for the 2025 Proposed Rule contains all information necessary to substantiate the EPA's decision-making process. The docket includes certain CBI-claimed information. Pursuant to 40 CFR 2.301(a)(2), information otherwise qualifying as CBI cannot be claimed as such if that information qualifies as “emission data” necessary for the EPA to disclose to demonstrate the feasibility, practicability, or attainability of an existing or proposed standard or limitation, under 40 CFR 2.301(a)(2)(ii)(B). Pursuant to 40 CFR 2.301(a)(2), “emission data” includes data necessary to determine the amount of emissions that the Keetac facility is authorized to emit. Here, redactions cover CBI-claimed information that does not qualify as “emission data,” and the EPA therefore does not need to include that information in the 2025 Proposed Rule. With respect to the cited Barr report, redacted information covered an economic analysis that purported to establish the cost prohibitiveness of a specific technology, but the EPA did not rely on purported cost prohibitiveness; U.S. Steel otherwise demonstrated the technical infeasibility of that technology.^[22] The cited Barr report is in the docket for the 2025 Proposed Rule because it provides background information on alternative technologies that U.S. Steel and the EPA considered—and discarded—as a feasible solution. The two FivesNA documents in the docket proposed two FivesNA burner solutions to reduce NO_X emissions at the Keetac grate kiln. One document evaluated the Keetac main burner and the other evaluated potential reductions at the preheat section of the grate kiln. The redacted data in the two FivesNA documents were not included in the docket because they were claimed as CBI and were not material to the EPA's decisions on emission limits. They were also not “emission data” as defined at 40 CFR 2.301(a)(2) because they were not necessary to determine the amount of emissions that the facility would be authorized to emit. The docket for this rulemaking contains all information necessary to substantiate the EPA's decision-making process.

Comment: The Conservation Groups contend that the EPA's reasons for proposing the FIP revision are not moored to the CAA. Rather than reducing pollution, the Conservation Groups assert that the proposed changes would allow Keetac to emit more haze-forming pollution in the future.

Response: The EPA disagrees that the reasons for proposing this action are inconsistent with the requirements of the CAA. CAA section 169A 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.” At a minimum, the CAA calls for SIPs to include a long-term strategy and provisions for BART for certain major stationary sources. The RHR codified and clarified the BART provisions at 40 CFR 51.308(e). As discussed in this section, the RHR requires States (or in the case of a FIP, the EPA) to develop an implementation plan that sets emission limits based on the degree of reduction achievable through the application of the best system of continuous emission reduction. As noted in this section and discussed in the 2025 Proposed Rule, the EPA conducted five-factor BART analyses in the Original 2013 FIP Rule and determined that LNB technology is BART for the Keetac facility. The initial LNB design selection for Keetac was based on LNB operation at U.S. Steel's Minntac facility and subsequent modeling demonstrated that the Minntac LNB design would be infeasible at Keetac due to several technical factors. Further studies determined that a different LNB main burner design, in combination with low-NO_X preheat burners, would be the most effective LNB design for Keetac. The BART limits proposed for Keetac in the 2025 Proposed Rule reflect the degree of reduction achievable based on operations and parameters specific to the Keetac facility.

Keetac has not yet installed the identified NO_X controls; therefore, installation of any NO_X controls—including those identified here— ( printed page 34580) necessarily result in NO_X reductions compared to what the Keetac facility is currently emitting.

Comment: The Conservation Groups assert that the 2025 Proposed Rule fails to include the details necessary for practical enforceability. The Conservation Groups further assert that the 2025 Proposed Rule fails to explain how the proposed revised regulations identified for inclusion in the FIP comply with the monitoring, recordkeeping, and reporting requirements of the CAA and provide adequate reporting—namely, CEMS compliance data—to the EPA for citizen enforcement.

Response: The EPA disagrees that the 2025 Proposed Rule for Keetac had insufficient detail to ensure practical enforceability. The regional haze regulations codified into the Minnesota SIP at 40 CFR 52.1235(c), (d), and (e) contain applicable monitoring, recordkeeping, and reporting requirements, which satisfy the requirement in 42 U.S.C. 7410(a)(2)(F)(iii) and 40 CFR 51.211 for record maintenance and periodic reporting. These requirements include semiannual compliance reports and quarterly excess emission reports detailing compliance with monitoring, recordkeeping, and reporting requirements.

Comment: The Conservation Groups contend that the 2025 Proposed Rule fails to specify that emission limits apply at all times for Keetac. The Conservation Groups also note that, although the EPA's prior proposal included such a provision for the Northshore Mining Company—Silver Bay facility (40 CFR 52.1235(b)(vi)), the Agency's current proposal for Keetac lacks a similar provision. The Conservation Groups assert that the EPA must act consistently and treat all the taconite sources in the same manner.

Response: The EPA disagrees with the Conservation Groups' contention that it was necessary for the 2025 Proposed Rule to specify that emission limits apply at all times for Keetac because the Original 2013 FIP Rule already clearly requires that the emission limits apply at all times and this action does not impact that provision. The Original 2013 FIP Rule, codified at 40 CFR 52.1235(e)(7)(x)(A), clearly states “For purposes of this section, an excess emission is defined as any 30-day or 720-hour rolling average period, including periods of startup, shutdown, and malfunction, during which the 30-day or 720-hour (as appropriate) rolling average emissions of either regulated pollutant (SO₂ and NO_X), as measured by a CEMS, exceeds the applicable emission standards in this section” (emphasis added).

Comment: An anonymous commenter asserts that the EPA should not loosen any standards ever. The anonymous commenter contends that the EPA's mission is to clean the air and water and that clean means the standard present before European arrival to America, and therefore the Agency will never be able to loosen standards.

Response: The EPA disagrees with commenter's contentions. The EPA's action is consistent with the CAA requirements and the applicable implementing regulations. The EPA does not agree that the commenter's summary of Agency's mission aligns with Congressional direction in the text of the CAA and, therefore, the comment does not articulate an applicable standard for this action. In this case, the EPA performed analyses required by the CAA and applicable regulations, including a BART analysis for Keetac, and determined that emission reductions based on implementation of LNB technology is BART for this facility. When Keetac installs this LNB technology at its facility, NO_X emissions will be reduced from current baseline levels.

Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review

This action is not a significant regulatory action as defined in Executive Order 12866 and is therefore not subject to a requirement for Executive Order 12866 review.

B. Executive Order 14192: Unleashing Prosperity Through Deregulation

This action is considered an Executive Order 14192 deregulatory action. This final rule provides burden reduction by promulgating less stringent emission limits.

C. Paperwork Reduction Act (PRA)

This action does not impose an information collection burden under the PRA.

D. Regulatory Flexibility Act (RFA)

I certify that this action will not have a significant economic impact on a substantial number of small entities under the RFA (5 U.S.C. 601 et seq.). This action will not impose any requirements on small entities. This action will establish emission limits for one taconite source. This source is not owned by a small entity, and therefore, there are no impacts on small entities.

E. Unfunded Mandates Reform Act (UMRA)

This action does not contain any unfunded mandate as described in UMRA, 2 U.S.C. 1531 through 1538, and does not significantly or uniquely affect small governments. The action imposes no enforceable duty on any State, local, or Tribal governments or the private sector.

F. Executive Order 13132: Federalism

This action does not have federalism implications. It will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government.

G. Executive Order 13175: Consultation and Coordination With Indian Tribal Governments

This rule does not have Tribal implications, as specified in Executive Order 13175. It will not have substantial direct effects on Tribal governments. Thus, Executive Order 13175 does not apply to this rule. However, the EPA did discuss this action in conference calls with the Minnesota Tribes.

H. Executive Order 13045: Protection of Children From Environmental Health and Safety Risks

This action is not subject to Executive Order 13045 because it is not 3(f)(1) significant as defined in Executive Order 12866.

I. Executive Order 13211: Actions That Significantly Affect Energy Supply, Distribution, or Use

This action is not subject to Executive Order 13211 because it is not a significant regulatory action under Executive Order 12866.

J. National Technology Transfer Advancement Act

This rulemaking does not involve technical standards.

K. Congressional Review Act

This rule is exempt from the Congressional Review Act because it is a rule of particular applicability.

L. Judicial Review

Under section 307(b)(1) of the CAA, petitions for judicial review of this action must be filed in the United States Court of Appeals for the appropriate circuit by August 7, 2026. Filing a petition for reconsideration by the Administrator of this final rule does not affect the finality of this rule for the purposes of judicial review or extend ( printed page 34581) the time within which a petition for judicial review may be filed, and shall not postpone the effectiveness of such rule or action. This action may not be challenged later in proceedings to enforce its requirements. See CAA section 307(b)(2).

For the reasons stated in the preamble, title 40 CFR part 52 is amended as follows:

91 FR 34574