Commitments and Contingencies	12 Months Ended
Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Overview There are various claims and lawsuits pending against the Company. In addition, the Company is subject to federal, state, and local environmental laws and regulations and periodically participates in the investigation and remediation of various sites. In addition, the Company periodically enters into financial commitments in connection with its business operations. Also, the Company is involved in various legal and regulatory proceedings in the normal course of its business. See Note 17. It is not possible at this time for the Company to determine fully the effect of all litigation and other legal and regulatory proceedings on its financial position, results of operations, or cash flows. With respect to some of the items listed below, the Company has determined that a loss is not probable or that, to the extent probable, cannot be reasonably estimated. In some cases, the Company is not able to predict with any degree of certainty the range of possible loss that could be incurred. The Company assesses legal and regulatory matters based on current information and makes judgments concerning their potential outcome, giving due consideration to the nature of the claim, the amount and nature of any damages sought, and the probability of success. Such judgments are made with the understanding that the outcome of any litigation, investigation, or other legal proceeding is inherently uncertain. The Company records liabilities for matters where it is probable a loss has been incurred and the amount of loss is reasonably estimatable. The actual outcomes of the items listed below could ultimately differ from the judgments made and the differences could be material. The Company cannot make any assurances that the amount of reserves or potential insurance coverage will be sufficient to cover the cash obligations that might be incurred as a result of litigation or regulatory proceedings. Except as otherwise disclosed, the Company does not expect that any known lawsuits, environmental costs, or commitments will have a material effect on its financial condition, results of operations, or cash flows. Commitments and Contingencies Related to the Environment PVNGS Decommissioning Funding The costs of decommissioning a nuclear power plant are substantial. PNM is responsible for all decommissioning obligations related to its entire interest in PVNGS, including portions under leases both during and after termination of the leases. PNM has a program for funding its share of decommissioning costs for PVNGS, including portions previously held under leases. The nuclear decommissioning funding program is invested in equities and fixed income instruments in qualified and non-qualified trusts. PNM funded $1.3 million for each of the years ended December 31, 2023, 2022 and 2021 into the qualified trust funds. The fair value of the trusts at December 31, 2023 and 2022 was $361.0 million and $325.3 million. See Note 17 for additional discussion of PNM’s PVNGS Lease Abandonment Application. Nuclear Spent Fuel and Waste Disposal Nuclear power plant operators are required to enter into spent fuel disposal contracts with the DOE that require the DOE to accept and dispose of all spent nuclear fuel and other high-level radioactive wastes generated by domestic power reactors. Although the Nuclear Waste Policy Act required the DOE to develop a permanent repository for the storage and disposal of spent nuclear fuel by 1998, the DOE announced that it would not be able to open the repository by 1998 and sought to excuse its performance of these requirements. In November 1997, the DC Circuit issued a decision preventing the DOE from excusing its own delay but refused to order the DOE to begin accepting spent nuclear fuel. Based on this decision and the DOE’s delay, a number of utilities, including APS (on behalf of itself and the other PVNGS owners, including PNM), filed damages actions against the DOE in the Court of Federal Claims. The lawsuits filed by APS alleged that damages were incurred due to DOE’s continuing failure to remove spent nuclear fuel and high-level waste from PVNGS. In August 2014, APS and the DOE entered into a settlement agreement that established a process for the payment of claims for costs incurred through December 31, 2019. APS has accepted the DOE’s extensions of the settlement agreement for recovery of costs incurred through December 31, 2025. Under the settlement agreement, APS must submit claims annually for payment of allowable costs. PNM records estimated claims on a quarterly basis. The benefit from the claims is passed through to customers under the FPPAC. PNM estimates that it will incur approximately $55.6 million (in 2023 dollars) for its share of the costs related to the on-site interim storage of spent nuclear fuel at PVNGS for the remaining term of the operating licenses. PNM accrues these costs as a component of fuel expense as the nuclear fuel is consumed. At December 31, 2023 and 2022, PNM had a liability for interim storage costs of $11.0 million and $12.0 million, which is included in other deferred credits. PVNGS has sufficient capacity at its on-site Independent Spent Fuel Storage Installation (“ISFSI”) to store all of the nuclear fuel that will be irradiated during the initial operating license period, which ends in December 2027. Additionally, PVNGS has sufficient capacity at its on-site ISFSI to store a portion of the fuel that will be irradiated during the period of extended operation, which ends in November 2047. If uncertainties regarding the U.S. government’s obligation to accept and store spent fuel are not favorably resolved, APS will evaluate alternative storage solutions that may obviate the need to expand the ISFSI to accommodate all of the fuel that will be irradiated during the period of extended operation. The Energy Transition Act In 2019, the Governor signed into New Mexico state law Senate Bill 489, known as the Energy Transition Act (“ETA”). The ETA became effective as of June 14, 2019 and sets a statewide standard that requires investor-owned electric utilities to have specified percentages of their electric-generating portfolios be from renewable and zero-carbon generating resources. The ETA requires utilities operating in New Mexico to have renewable portfolios equal to 40% by 2025, 50% by 2030, 80% by 2040, and 100% zero-carbon energy by 2045. The ETA also allows for the recovery of undepreciated investments and decommissioning costs related to qualifying EGUs that the NMPRC has required be removed from retail jurisdictional rates, provided replacement resources to be included in retail rates have lower or zero-carbon emissions. The ETA requires the NMPRC to review and approve utilities’ annual renewable portfolio plans to ensure compliance with the RPS. The ETA also directs the New Mexico Environmental Improvement Board to adopt standards of performance that limit CO2 emissions to no more than 1,100 lbs per MWh beginning January 1, 2023 for new or existing coal-fired EGUs with original installed capacities exceeding 300 MW. The ETA provides for a transition from fossil-fuel generation resources to renewable and other carbon-free resources through certain provisions relating to the abandonment of coal-fired generating facilities. These provisions include the use of energy transition bonds, which are designed to be highly rated bonds that can be issued to finance certain costs of abandoning coal-fired facilities that are retired prior to January 1, 2023 for facilities operated by a “qualifying utility,” or prior to January 1, 2032 for facilities that are not operated by a qualifying utility. The amount of energy transition bonds that can be issued to recover abandonment costs is limited to the lesser of $375.0 million or 150% of the undepreciated investment of the facility as of the abandonment date. Proceeds provided by energy transition bonds must be used only for purposes related to providing utility service to customers and to pay energy transition costs (as defined by the ETA). These costs may include plant decommissioning and coal mine reclamation costs, provided those costs have not previously been recovered from customers or disallowed by the NMPRC or by a court order. Proceeds from energy transition bonds may also be used to fund severances for employees of the retired facility and related coal mine and to promote economic development, education and job training in areas impacted by the retirement of the coal-fired facilities. Energy transition bonds must be issued under a NMPRC approved financing order, are secured by “energy transition property,” are non-recourse to the issuing utility, and are repaid by a non-bypassable charge paid by all customers of the issuing utility. These customer charges are subject to an adjustment mechanism designed to provide for timely and complete payment of principal and interest due under the energy transition bonds. The ETA also provides that utilities must obtain NMPRC approval of competitively procured replacement resources that shall be evaluated based on their cost, economic development opportunity, ability to provide jobs with comparable pay and benefits to those lost upon retirement of the facility and that do not exceed emissions thresholds specified in the ETA. In determining whether to approve replacement resources, the NMPRC must give preference to resources with the least environmental impacts, those with higher ratios of capital costs to fuel costs, and those located in the school district of the abandoned facility. The ETA also provides for the procurement of energy storage facilities and gives utilities discretion to maintain, control, and operate these systems to ensure reliable and efficient service. The ETA has had and will have a significant impact on PNM’s future generation portfolio, including PNM’s retirement of SJGS in 2022 and the exit of Four Corners (subject to regulatory approval). PNM cannot predict the full impact of the ETA or the outcome of its pending and potential future generating resource abandonment and replacement resource filings with the NMPRC. See additional discussion in Note 17 of PNM’s SJGS and Four Corners Abandonment Applications. The Clean Air Act Regional Haze Pursuant to the CAA, states are required to establish goals for improving visibility in national parks and wilderness areas (also known as Class I areas) and to develop long-term strategies for reducing emissions of air pollutants that cause visibility impairment in their own states and for preventing degradation in other states. States must establish a series of interim goals to ensure continued progress by adopting a new SIP every ten years. In the first SIP planning period, states were required to conduct BART determinations for certain covered facilities, including utility boilers, built between 1962 and 1977 that have the potential to emit more than 250 tons per year of visibility impairing pollution. For all future SIP planning periods, states must evaluate whether additional emissions reduction measures may be needed to continue making reasonable progress toward natural visibility conditions. In 2017, EPA published revisions to the regional haze rule in the Federal Register that delayed the due date for the next cycle of SIPs from 2019 to 2021 and altered the planning process that states must employ in determining whether to impose “reasonable progress” emission reduction measures. EPA’s new rule was challenged by numerous parties, but the litigation was held in abeyance after EPA granted various petitions for reconsideration. In 2018, EPA released a new guidance document on tracking visibility progress for the second planning period. EPA is allowing states discretion to develop SIPs that may differ from EPA’s guidance as long as they are consistent with the CAA and other applicable regulations. In 2019, EPA finalized the draft guidance that was previously released as a companion to the regional haze rule revisions, and EPA clarified that guidance in a memorandum issued in 2021. SIPs for the second planning period were due in July 2021, which deadline NMED was unable to meet. NMED is currently preparing its SIP for the second compliance period and has notified PNM that it will not be required to submit a regional haze four-factor analysis for SJGS since PNM retired its share of SJGS in 2022. On August 30, 2022, EPA published in the Federal Register an official “Finding of Failure to Submit” for states, including New Mexico, that have not yet submitted a round 2 regional haze SIP. This action by EPA starts a 2-year clock for it to issue a Federal Implementation Plan (FIP). NMED’s current timeline indicates the proposed SIP will be submitted to EPA by Summer 2024. Carbon Dioxide Emissions In 2015, EPA established standards to limit CO2 emissions from power plants, including (1) Carbon Pollution Standards for new, modified, and reconstructed power plants; and (2) the Clean Power Plan for existing power plants. Multiple states, utilities, and trade groups challenged both the Carbon Pollution Standards for new sources and the Clean Power Plan for existing sources in separate cases. Challengers successfully petitioned the US Supreme Court for a stay of the Clean Power Plan. However, before the DC Circuit could issue an opinion regarding either the Carbon Pollution Standards or the Clean Power Plan, the Trump Administration asked that the case be held in abeyance while the rules were reevaluated, which was granted. In 2019, EPA repealed the Clean Power Plan, promulgated the ACE Rule, and revised the implementing regulations for all emission guidelines. EPA set the BSER for existing coal-fired power plants as heat rate efficiency improvements based on a range of “candidate technologies” that can be applied inside the fence line of an individual facility. The DC Circuit issued an order that granted motions by various petitioners, including industry groups and EPA, to dismiss the cases challenging the Clean Power Plan as moot due to EPA’s issuance of the ACE Rule. The ACE Rule was also challenged, and on January 19, 2021, the DC Circuit issued an opinion in American Lung Association and American Public Health Association v. EPA, et al., vacating the ACE Rule. While the DC Circuit rejected the ACE Rule, it did not reinstate the Clean Power Plan. Rather, the DC Circuit granted an EPA motion asking the court to withhold issuance of the mandate with respect to the repeal of the Clean Power Plan until EPA responds to the court’s remand in a new rulemaking action. Numerous parties sought review by the US Supreme Court, and on June 30, 2022, the Court held that the “generation shifting” approach in the Clean Power Plan exceeded the powers granted to EPA by Congress, though the Court did not address the related issue of whether Section 111 of the CAA only authorizes EPA to require measures that can be implemented entirely within the fence line at an individual source. Of broader significance in administrative law, the Court’s opinion expressly invoked the “major question” doctrine, which requires rules involving issues of “vast economic or political significance” to be supported by clear statutory authorization. In cases where there is no clear statement of authority, courts need not defer to the agency’s statutory interpretation on “major questions.” The decision sets legal precedent for future rulemakings by EPA and other federal regulatory agencies whereby the agencies’ authority may be limited based upon similar reasoning. The litigation over the Carbon Pollution Standards remains held in abeyance but could be reactivated by the parties upon a determination by the court that reconsideration of the rule has concluded. On May 23, 2023, EPA published in the Federal Register proposed regulatory actions under CAA sections 111(b) and (d) to replace the Clean Power Plan and the ACE Rule. The proposed regulations cover: (1) New natural gas-based EGUs under section 111(b); (2) Existing large and frequently operated natural gas-based EGUs under section 111(d); and (3) Existing coal-based EGUs under section 111(d). Standards of performance for existing coal EGUs will be based on two technologies depending on retirement date: carbon capture and storage/sequestration (“CCS”) or co-firing gas in lieu of coal. For gas-based EGUs, the standards will be based on CCS or the use of green hydrogen in lieu of natural gas. States will be required to develop SIPs to EPA that provide for the establishment, implementation and enforcement of these standards as they apply to existing sources. States may take into account remaining useful life and other factors when establishing the standards. EPA is proposing that existing coal units must start complying with their gas co-firing or CCS based standards of performance on January 1, 2030, unless they commit to retirement before 2032 (or retirement by 2035 if they also commit to a 20% annual operating limit). Existing combustion turbine units must start complying with their hydrogen or CCS based standards of performance on January 1, 2032, or January 1, 2035, depending on their subcategory, which is based on the control technology selected. The package also includes a proposed repeal of the ACE rule and revisions to the standard for modified and reconstructed units, along with a notice of public rulemaking seeking data and information about setting standards for existing smaller natural gas-based generators. Comments on the rule were due to EPA by August 8, 2023. PNM filed company-specific comments and continues to review the proposed rule and its potential impacts on the company’s fossil generation resources. EPA has indicated it plans to promulgate a final rule by Spring 2024. On January 27, 2021, President Biden signed an extensive Executive Order aimed at addressing climate change concerns domestically and internationally. The order is intended to build on the initial climate-related actions the Biden Administration took on January 20, 2021. It addresses a wide range of issues, including establishing climate change concerns as an essential element of U.S. foreign and security policy, identifying a process to determine the U.S. INDC under the Paris Agreement, and establishing a Special Presidential Envoy for Climate that will sit on the National Security Council. On April 22, 2021, at the Earth Day Summit, as part of the U.S.’s re-entry into the Paris Agreement, President Biden unveiled the goal to cut U.S. emissions by 50% - 52% from 2005 levels by 2030, nearly double the GHG emissions reduction target set by the Obama Administration. The 2030 goal joins President Biden’s other climate goals which include a carbon pollution-free power sector by 2035 and a net-zero emissions economy by no later than 2050. PNM’s review of the GHG emission reductions standards that may occur as a result of legislation or regulation under the Biden Administration and in response to the court’s ruling on the ACE Rule is ongoing. PNM cannot predict the impact these standards may have on its operations or a range of the potential costs of compliance, if any. National Ambient Air Quality Standards (“NAAQS”) The CAA requires EPA to set NAAQS for pollutants reasonably anticipated to endanger public health or welfare. EPA has set NAAQS for certain pollutants, including NOx, SO2, ozone, and particulate matter. NOX Standard – In 2018, EPA published the final rule to retain the current primary health-based NOx standards of which NO2 is the constituent of greatest concern and is the indicator for the primary NAAQS. EPA concluded that the current 1-hour and annual primary NO2 standards are requisite to protect public health with an adequate margin of safety. The rule became effective on May 18, 2018. The State of New Mexico has attained the current NOx NAAQS standards. SO2 Standard – In 2019, EPA announced its final decision to retain, without changes, the primary health-based NAAQS for SO2. Specifically, EPA will retain the current 1-hour standard for SO2, which is 75 parts per billion, based on the 3-year average of the 99th percentile of daily maximum 1-hour SO2 concentrations. On March 26, 2021, EPA published in the Federal Register the initial air quality designations for all remaining areas not yet designated under the 2010 SO2 Primary NAAQS. All areas of New Mexico have been designated attainment/unclassifiable through four rounds of designations by EPA. Ozone Standard – In 2015, EPA finalized the new ozone NAAQS and lowered both the primary and secondary 8-hour standard from 75 to 70 parts per billion. With ozone standards becoming more stringent, fossil-fueled generation units will come under increasing pressure to reduce emissions of NOx and volatile organic compounds since these are the pollutants that form ground-level ozone. On July 13, 2020, EPA proposed to retain the existing ozone NAAQS based on a review of the full body of currently available scientific evidence and exposure/risk information. EPA finalized its decision to retain the ozone NAAQS in a notice published on December 31, 2020 making it immediately effective. In response to lawsuits brought by states and environmental groups, on October 29, 2021, EPA filed a motion in the DC Circuit indicating it will reconsider the 2020 ozone NAAQS. On August 21, 2023, EPA announced an entirely new review of the ozone standard that will incorporate the work to date on the reconsideration, likely indicating a delay in the schedule for a decision on whether the standard should be revised. On January 3, 2024, EPA filed in the DC Circuit an unopposed motion for voluntary remand, without vacatur, of EPA’s final rule retaining the current ozone NAAQS. The filing was made in the consolidated cases challenging the 2020 ozone NAAQS rule. During 2017 and 2018, EPA released rules establishing area designations for ozone. In those rules, San Juan County, New Mexico, where Four Corners is located, is designated as attainment/unclassifiable and only a small area in Doña Ana County, New Mexico is designated as marginal non-attainment. Although Afton Generating Station is located in Doña Ana County, it is not located within the small area designated as non-attainment for the 2015 ozone standard. The rule became effective May 8, 2018. NMED has responsibility for bringing the small area in Doña Ana County designated as marginal/non-attainment for ozone into compliance and will look at all sources of NOx and volatile organic compounds. NMED has submitted the required elements for the Sunland Park Ozone Non-attainment Area SIP. This includes a transportation conformity demonstration, a 2017 baseline emissions inventory and emissions statement, and an amendment to the state’s Non-attainment Permitting rules at 20.2.79 New Mexico Administrative Code to conform to EPA’s SIP Requirements Rule for 2015 Q3 NAAQS (i.e., “implementation rule”). The SIP elements had staggered deadlines and were done in three submissions: (1) the transportation conformity demonstration was completed by the El Paso Metropolitan Planning Organization on behalf of New Mexico in 2019, which is responsible for transportation planning in that area, and the submission received concurrence from EPA and the Federal Highway Administration; (2) the emissions inventory and statement SIP was submitted to EPA in September 2020; and (3) the Non-attainment New Source Review SIP was submitted to EPA on August 10, 2021. On October 15, 2021, EPA proposed to approve New Mexico’s SIP to meet the emissions inventory and statement requirements of the CAA for the Sunland Park Ozone Non-Attainment Area. PNM does not believe there will be material impacts to its facilities because of NMED’s non-attainment designation of the small area within Doña Ana County. Until EPA approves attainment designations for the Navajo Nation and releases a proposal to implement the revised ozone NAAQS, PNM is unable to predict what impact the adoption of these standards may have on Four Corners. With respect to EPA’s reconsideration of the 2020 decision to retain the 2015 ozone standards, EPA is statutorily obligated to complete its review of the ozone standards by December 2025. PNM cannot predict the outcome of this matter. In 2019, EPA issued findings that several states, including New Mexico, had failed to submit interstate transport SIPs for the 2015 8-hour ozone NAAQS, triggering an obligation for EPA to issue a federal implementation plan within two years. In response, NMED submitted a Good Neighbor SIP on July 27, 2021 that demonstrates that there are no significant contributions from New Mexico to downwind problems in meeting the federal ozone standard. Nevertheless, when EPA failed to approve the SIP or issue a FIP within two years of the finding of failure to submit, multiple parties filed a deadline suit against EPA, resulting in a consent decree requiring EPA to issue a FIP or approve a SIP for New Mexico by a deadline of no later than June 1, 2024, which was later extended to August 30, 2024. On March 15, 2023, EPA Administrator Regan signed a final action imposing a FIP on multiple states but did not include a FIP for New Mexico because EPA had not proposed a FIP for the state because the most up to date modeling available at proposal confirmed the state did not contribute to downwind ozone nonattainment or maintenance areas. However, the updated modeling EPA used in the final rule indicated that New Mexico may be significantly contributing to one or more non-attainment or maintenance areas. In light of that modeling result, on February 16, 2024, EPA proposed to impose a FIP on New Mexico to address the newly identified contribution. If finalized as proposed, the FIP would require specified fossil fuel-fired generating resources to participate in an ozone-season NOx emission allowance trading program that will limit total NOx emissions from all affected units within the state of New Mexico. PM Standard – On January 30, 2020, EPA published in the Federal Register a notice announcing the availability of a final Policy Assessment for the Review of the NAAQS for Particulate Matter (the “PA”). The 2020 final PA was prepared as part of the review of the primary and secondary PM NAAQS. In the 2020 final PA, EPA recommended lowering the primary annual PM 2.5 standard to between 8 µg/m3 and 10 µg/m3. However, on April 30, 2020, EPA published a proposed rule to retain the current standards for PM due to uncertainties in the data relied upon in the 2020 final PA and EPA published a notice of that final action on December 18, 2020, making it immediately effective. On January 14, 2021, several states and New York City filed a petition for review in the DC Circuit, challenging EPA’s final rule retaining the current primary and secondary PM NAAQS and a similar lawsuit was filed by the Center for Biological Diversity in the DC Circuit. On June 10, 2021, EPA announced that it will reconsider the previous administration’s December 2020 decision to retain the current primary and secondary PM NAAQS and on October 8, 2021, EPA announced the release of a new draft PA stating that available scientific evidence and technical information indicate that the current standards may not be adequate to protect public health and welfare, as required by the CAA. On June 1, 2022, EPA issued a new final PA that likewise indicates current standards may not be adequate and that available scientific evidence could support lowering the standards. On January 27, 2023, EPA published, in the Federal Register, a proposal to lower the annual fine PM standard to between 9-10 µg/m3 but retain the rest of its PM standards, including the current daily fine particulate matter standard, the daily coarse particulate matter standard, and the secondary PM standards. EPA issued a prepublication of the final rule on February 7, 2024, lowering the fine PM standard to 9 ug/m3. Although the lower standard is expected to result in new nonattainment areas throughout the country and could prompt additional PM control requirements, PNM cannot predict the impacts of the outcome of future rulemaking. Cooling Water Intake Structures In 2014, EPA issued a rule establishing national standards for certain cooling water intake structures at existing power plants and other facilities under the Clean Water Act to protect fish and other aquatic organisms by minimizing impingement mortality (the capture of aquatic wildlife on intake structures or against screens) and entrainment mortality (the capture of fish or shellfish in water flow entering and passing through intake structures). To minimize impingement mortality, the rule provides operators of facilities, such as Four Corners, seven options for meeting Best Technology Available (“BTA”) standards for reducing impingement. The permitting authority must establish the BTA for entrainment on a site-specific basis, taking into consideration an array of factors, including endangered species and social costs and benefits. Affected sources must submit source water baseline characterization data to the permitting authority to assist in the determination. Compliance deadlines under the rule are tied to permit renewal and will be subject to a schedule of compliance established by the permitting authority. In 2018, several environmental groups sued EPA Region IX in the U.S. Court of Appeals for the Ninth Circuit Court over EPA’s failure to timely reissue the Four Corners NPDES permit. The petitioners asked the court to issue a writ of mandamus compelling EPA Region IX to take final action on the pending NPDES permit by a reasonable date. EPA subsequently reissued the NPDES permit. The permit did not contain conditions related to the cooling water intake structure rule, as EPA determined that the facility has achieved BTA for both impingement and entrainment by operating a closed-cycle recirculation system. Several environmental groups filed a petition for review with EPA’s Environmental Appeals Board (“EAB”) concerning the reissued permit. The environmental groups alleged that the permit was reissued in contravention of several requirements under the Clean Water Act and did not contain required provisions concerning certain revised ELG, existing-source regulations governing cooling-water intake structures, and effluent limits for surface seepage and subsurface discharges from coal-ash disposal facilities. EPA withdrew the Four Corners NPDES permit in order to examine issues raised by the environmental groups. Withdrawal of the permit moots the appeal pending before the EAB. EAB thereafter dismissed the environmental groups’ appeal. EPA issued an updated NPDES permit in 2019. The permit was once again appealed to the EAB and was stayed before the effective date. Oral argument was heard on September 3, 2020. The EAB issued an order denying the petition for review on September 30, 2020. The denial was based on the EAB’s determination that the petitioners had failed to demonstrate that review of the permit was warranted on any of the grounds presented in the petition. Thereafter, the Regional Administrator of the EPA signed a notice of final permit decision, and the NPDES permit was issued on November 9, 2020. The permit became effective December 1, 2020 and will expire on November 30, 2025. On January 22, 2021, the environmental groups filed a petition for review of the EAB’s decision with the U.S. Court of Appeals for the Ninth Circuit. The September 2019 permit remains in effect pending this appeal. On March 21, 2022, EPA provided notice in the Federal Register of a proposed settlement agreement with the environmental groups. The parties subsequently executed the settlement agreement as of May 2, 2022. Under the settlement, the associated case was administratively closed through September 6, 2023, during which time a third-party consultant spent 12 months sampling discharges from Four Corners and EPA spent three months completing an analysis. On December 1, 2023, EPA issued a modification, effective December 31, 2023, to the NPDES permit issued on November 9, 2020. The modification applies to permit elements related to effluent discharge. PNM cannot predict whether the analysis under the settlement agreement will result in changes to the NPDES permit but does not anticipate that it will have a material impact on PNM’s financial position, results of operations, or cash flows. Effluent Limitation Guidelines In 2013, EPA published proposed revised wastewater ELG establishing technology-based wastewater discharge limitations for fossil fuel-fired electric power plants. EPA signed the final Steam Electric ELG rule in 2015. The final rule, which became effective on January 4, 2016, phased in the new, more stringent requirements in the form of effluent limits for arsenic, mercury, selenium, and nitrogen for wastewater discharged from wet scrubber systems and zero discharge of pollutants in ash transport water that must be incorporated into plants’ NPDES permits. The 2015 rule required each plant to comply between 2018 and 2023 depending on when it needs a new or revised NPDES permit. The Steam Electric ELG rule was challenged in the U.S. Court of Appeals for the Fifth Circuit by numerous parties. In 2017, EPA signed a notice indicating its intent to reconsider portions of the rule, and the Fifth Circuit issued an order severing the issues under reconsideration and holding the case in abeyance as to those issues. However, the court allowed challenges to other portions of the rule to proceed. In 2019, the Fifth Circuit granted those challenges and issued an opinion vacating several portions of the rule, specifically those related to legacy wastewater and leachate, for which the court deemed the standards selected by EPA arbitrary and capricious. In 2017, EPA published a final rule for postponement of certain compliance dates. The rule postponed the earliest date on which compliance with the ELG for these waste streams would be required from November 1, 2018 until November 1, 2020. In 2019, EPA published a proposed rule revising the original ELG while maintaining the compliance dates. In 2020, EPA published in the Federal Register the final Steam Electric ELG and standards for the Steam Electric Power Generating Point Source Category, revising the final 2015 guidelines for both flue gas desulfurization wastewater and bottom ash transport water. The rule requires compliance with new limits as soon as possible on or after October 13, 2021, but no later than December 31, 2025. On August 3, 2021, EPA published notice that it will undertake a supplemental rulemaking to revise the ELG after completing its review of the rules reconsidered in 2020. As part of this process, EPA will determine whether more stringent limitations and standards are appropriate. On March 29, 2023, EPA published the proposed ELG Rule in the Federal Register. The proposed rule includes stricter limitations on bottom ash transport water, flue gas desulfurization, and coal combustion residual leachate. Also included are flexibilities for coal-powered facilities that will soon decommission or repower. With this proposed rule EPA has extended the date of decommissioning or repowering from December 31, 2028, to December 31, 2032. Comments on the proposed rule were due May 30, 2023. A final rule is expected in April 2024. Reeves Station discharges cooling tower blowdown to a publicly owned treatment plant and no longer holds an NPDES permit; therefore, it is expected that no requirements will be imposed. See “Cooling Water Intake Structures” above for additional discussion of Four Corners’ current NPDES permit. Four Corners may be required to change equipment and operating practices affecting boilers and ash handling systems, as well as change its waste disposal techniques during the next NPDES permit renewal in 2023. PNM is unable to predict the outcome of these matters or a range of the potential costs of compliance. Santa Fe Generating Station PNM and NMED are parties to agreements under which PNM has installed a remediation system to treat water from a City of Santa Fe municipal supply well and an extraction well to address gasoline contamination in the groundwater at the site of PNM’s former Santa Fe Generating Station and service center. A 2008 NMED site inspection report states that neither the source nor extent of contamination at the site has been determined and that the source may not be the former Santa Fe Generating Station. During 2013 and 2014, PNM and NMED collected additional samples that showed elevated concentrations of nitrate and volatile organic compounds in some of the monitoring wells at the site. In addition, one monitoring well contained free-phase hydrocarbon products. PNM collected a sample of the product for “fingerprint” analysis. The results of this analysis indicated the product was a mixture of older and newer fuels. The presence of newer fuels in the sample suggests the hydrocarbon product likely originated from off-site sources. In 2015, PNM and NMED entered into a memorandum of understanding to address changing groundwater conditions at the site under which PNM agreed to continue hydrocarbon investigation under the supervision of NMED. Qualified costs are eligible for payment through the New Mexico Corrective Action Fund (“CAF”), which is administered by the NMED Petroleum Storage Tank Bureau. In 2019, PNM received notice from NMED that an abatement plan for the site is required to address concentrations of previously identified compounds, unrelated to those discussed above, found in the groundwater. NMED approved PNM’s abatement plan proposal, which covers field work and reporting. Field work related to the investigation under both the CAF and abatement plan requirements was completed and activities and findings associated with the field work were presented in two separate reports and released to stakeholders in early 2020. Subsequent field work was completed in July 2020 and two reports were released supporting PNM’s contention that off-site sources have impacted, and are continuing to impact, the local groundwater in the vicinity of the former Santa Fe Generating Station. PNM submitted work plans to NMED in January 2021 for review and approval. In December 2021, NMED approved both work plans and work activities were completed by the end of 2022. A report was submitted to the NMED in the first quarter of 2023. Groundwater sampling for the abatement plan’s first semiannual work commenced at the beginning of March 2023 and was completed in April 2023. The associated report was completed and submitted to the NMED in July 2023. In addition, the work plan for the 2023 CAF work was completed and submitted to the NMED in July 2023. NMED approved the work plan in December 2023 and PNM is working to schedule the associated activities. The City of Santa Fe has stopped operating its well at the site, which is needed for PNM’s groundwater remediation system to operate. As a result, PNM has stopped performing remediation activities at the site. However, PNM’s monitoring and other abatement activities at the site are ongoing and will continue until the groundwater meets applicable federal and state standards or until the NMED determines remediation is not required, whichever is earlier. PNM is not able to assess the duration of this project or estimate the impact on its obligations if PNM is required to resume groundwater remediation activities at the site. PNM is unable to predict the outcome of these matters. Coal Combustion Residuals Waste Disposal CCRs consisting of fly ash, bottom ash, and gypsum generated from coal combustion and emission control equipment at SJGS are currently disposed of in the surface mine pits adjacent to the plant. SJGS does not operate any CCR impoundments or landfills. The NMMMD currently regulates mine reclamation activities at the San Juan mine, including placement of CCRs in the surface mine pits, with federal oversight by the OSM. APS disposes of CCRs in ponds and dry storage areas at Four Corners. Ash management at Four Corners is regulated by EPA and the New Mexico State Engineer’s Office. EPA’s final coal ash rule, which became effective in 2015, included a non-hazardous waste determination for coal ash and sets minimum criteria for existing and new CCR landfills and surface impoundments. In 2016, the Water Infrastructure Improvements for the Nation Act (the “WIIN Act”) was signed into law to address critical water infrastructure needs in the U.S. and contains a number of provisions related to the CCR rules. Among other things, the WIIN Act allows, but does not require, states to develop and submit CCR permit programs for EPA approval, provides flexibility for states to incorporate EPA’s final rule for CCRs or develop other criteria that are at least as protective as EPA’s final rule, and requires EPA to approve state permit programs within 180 days of submission by the state. Because states are not required to implement their own CCR permit programs, EPA will implement the permit program in states that choose not to implement a program, subject to Congressional funding. Until permit programs are in effect, EPA has authority to directly enforce the CCR rule. For facilities located within the boundaries of Native American reservations, such as the Navajo Nation where Four Corners is located, EPA is required to develop a federal permit program regardless of appropriated funds. In 2018, EPA published a rule that constitutes “Phase One, Part One” of its ongoing reconsideration and revision of the April 17, 2015, CCR rule. The final Phase One, Part One rule includes two types of revisions. The first revision extended the deadline to allow EGUs with unlined impoundments or that fail to meet the uppermost aquifer requirement to continue to receive coal ash until October 31, 2020. This deadline was again extended by subsequent amendments. The rule also authorized a “Participating State Director” or EPA to approve suspension of groundwater monitoring requirements and to issue certifications related to the location restrictions, design criteria, groundwater monitoring, remedy selection and implementation. The rule also modified groundwater protection standards for certain constituents, which include cobalt, molybdenum, lithium, and lead without a maximum contamination level. In 2019, EPA published a second round of revisions, which are commonly referred to as the “Phase Two” revisions. Phase Two proposed revisions to reporting and accessibility to public information, the “CCR piles” and “beneficial use” definitions and the requirements for management of CCR piles. EPA has reopened and extended the Phase Two comment period several times. EPA has not yet finalized provisions in Phase Two related to beneficial use of CCR and CCR piles. This activity is on EPA’s long-term agenda, which means EPA has no plans to address these issues in the next 12 months. Since promulgating its Phase Two proposal, EPA has finalized two other rules addressing various CCR rule provisions. In 2019, EPA promulgated its proposed Holistic Approach to Closure Part A (“Part A”), which proposed a new deadline of August 31, 2020, for companies to initiate closure of unlined CCR impoundments. In accordance with the DC Circuit Court of Appeals’ vacatur of portions of the CCR Rule, Part A also proposed changing the classification of compacted soil-lined or clay-lined surface impoundments from “lined” to “unlined”. In addition, Part A delineated a process for owners/operators to submit requests for alternative closure deadlines based on lack of alternate disposal capacity. EPA issued the final Part A, which became effective on September 28, 2020. This rule finalized the classification of soil-lined and clay-lined surface impoundments as unlined, thus, triggering closure or retrofit requirements for those impoundments. The final Part A also gave operators of unlined impoundments until April 11, 2021 to cease receipt of waste at these units and initiate closure. In 2020, EPA issued the proposed Holistic Approach to Closure Part B (“Part B”), which delineated the process for owners/operators to submit alternate liner demonstrations for clay-lined surface impoundments that could otherwise meet applicable requirements. Part B also proposed regulations addressing beneficial use for closure of surface impoundments. EPA issued the final Part B rule, which became effective on December 14, 2020. This rule did not include beneficial use of CCR for closure, which EPA explains will be addressed in subsequent rulemaking actions. On May 18, 2023, EPA published a proposed rule on the regulatory requirements for inactive surface impoundments at inactive facilities including groundwater monitoring, corrective action, closure, and post-closure care requirements for all CCR management units (regardless of how or when that CCR was placed), and several technical corrections to the existing regulations. Comments on the proposed rule were due July 17, 2023. A final rule is expected April 2024. EPA intends to issue other rulemakings and finalizing parts of previously proposed rules, including a final rule in October 2024 on remaining Part B issues regarding closure options and annual reporting. In 2020, EPA published a proposed rule establishing a federal permitting program for the handling of CCR within the boundaries of Native American reservations and in states without their own federally authorized state programs. Permits for units within the boundaries of Native American reservations would be due 18 months after the effective date of the rule. According to the Fall 2023 Regulatory Agenda the final rule is expected in March 2026. EPA is coordinating with the affected permits for the three facilities with CCR disposal units located on Native American lands. PNM cannot predict the outcome of EPA’s rulemaking activity or the outcome of any related litigation, and whether or how such a ruling would affect operations at Four Corners. The CCR rule does not cover mine placement of coal ash. OSM is expected to publish a proposed rule covering mine placement in the future and will likely be influenced by EPA’s rule and the determination by EPA that CCRs are non-hazardous. PNM cannot predict the outcome of OSM’s proposed rulemaking regarding CCR regulation, including mine placement of CCRs, or whether OSM’s actions will have a material impact on PNM’s operations, financial position, or cash flows. Based upon the requirements of the final Part A CCR rule, PNM conducted a CCR assessment at SJGS and made minor modifications at the plant to ensure that there are no facilities that would be considered impoundments or landfills under the rule. PNM would seek recovery from its retail customers of all CCR costs for jurisdictional assets that are ultimately incurred. Utilities that own or operate CCR disposal units, such as those at Four Corners, as indicated above, were required to collect sufficient groundwater sampling data to initiate a detection monitoring program. Four Corners completed the analysis for its CCR disposal units, which identified several units that needed corrective action or needed to cease operations and initiate closure by April 11, 2021. Work is ongoing. Four Corners continues to gather additional groundwater data and perform remedial evaluations and activities. At this time, PNM does not anticipate its share of the cost to complete these corrective actions to close the CCR disposal units, or to gather and perform remedial evaluations on groundwater at Four Corners, will have a significant impact on its operations, financial position, or cash flows. Other Commitments and Contingencies Coal Supply SJGS The coal requirements for SJGS were supplied by WSJ LLC. Pricing under the SJGS CSA was primarily fixed, with adjustments to reflect changes in general inflation. Substantially all of SJGS’s coal costs were passed through the FPPAC. See additional discussion of PNM’s SJGS Abandonment Application Note 17. Four Corners APS purchases all of Four Corners’ coal requirements from NTEC, an entity owned by the Navajo Nation, under the Four Corners CSA that expires in 2031. The coal comes from reserves located within the Navajo Nation. The contract provides for pricing adjustments over its term based on economic indices and includes certain minimum payments that may be required if no deliveries of coal are taken. As of December 31, 2023 those minimum payments were $39.9 million for 2024, $81.8 million for 2025 and 2026, $83.8 million for 2027 and 2028, and $111.6 million for 2029 and thereafter. PNM’s share of the coal costs is being recovered through the FPPAC. Coal Mine Reclamation As indicated under Coal Combustion Residuals Waste Disposal above, SJGS disposed of CCRs in the surface mine pits adjacent to the plant and Four Corners disposes of CCRs in ponds and dry storage areas. Under the terms of the SJGS CSA, PNM and the other SJGS owners are obligated to compensate WSJ LLC for all reclamation costs associated with the supply of coal from the San Juan mine. PNM and Westmoreland have entered into an agreement under which mine reclamation services for SJGS would be provided. In 2020, a mine reclamation cost study was completed for the mine that serves SJGS. PNM’s estimate of the costs necessary to reclaim the mine that serves SJGS is subject to many assumptions, including the timing of reclamation, generally accepted practices at the time reclamation activities occur, and current inflation and discount rates. PNM cannot predict the ultimate cost to reclaim the mine that serves SJGS and would seek to recover all costs related to reclaiming the underground mine from its customers but could be exposed to additional loss related to surface mine reclamation. Additionally, in connection with certain mining permits relating to the operation of the San Juan mine, Westmoreland was required to post reclamation bonds of $118.7 million with the NMMMD. In order to facilitate the posting of reclamation bonds by sureties on behalf of Westmoreland, PNMR entered into the WFB LOC Facility under which letters of credit aggregating $30.3 million have been issued. A coal mine reclamation study for the mine that serves Four Corners was issued in 2019. The study reflected operation of the mine through 2031, the term of the Four Corners CSA. As discussed in Note 17, PNM remains responsible for its share of costs associated with mine reclamation under the Four Corners Purchase and Sale Agreement with NTEC. The Company is evaluating the facts and circumstances surrounding the exit of Four Corners and will determine next steps. Based on the most recent estimates, PNM’s remaining payments for mine reclamation, in future dollars, are estimated to be $53.6 million for the surface mines at both SJGS and Four Corners and $30.4 million for the underground mine at SJGS as of December 31, 2023. At December 31, 2023 and 2022, liabilities, in current dollars, of $50.0 million and $62.6 million for surface mine reclamation and $26.2 million and $28.2 million for underground mine reclamation were recorded in other deferred credits. The SJGS owners entered into a reclamation trust funds agreement to provide funding to compensate WSJ LLC for post-term reclamation obligations. The trust funds agreement requires each owner to enter into an individual trust agreement with a financial institution as trustee, create an irrevocable reclamation trust, and periodically deposit funds into the reclamation trust for the owner’s share of the mine reclamation obligation. Deposits, which are based on funding curves, must be made on an annual basis. PNM funded $2.7 million in 2023, $10.0 million in 2022, and $5.2 million in 2021. Based on PNM’s reclamation trust fund balance at December 31, 2023, the current funding curves indicate PNM’s required contributions to its reclamation trust fund would be zero in each of the years 2024, 2025, and 2026. Under the Four Corners CSA, PNM is required to fund its share of estimated final reclamation costs in annual installments into an irrevocable escrow account solely dedicated to the final reclamation cost of the surface mine at Four Corners. PNM contributed $0.2 million in 2023, $2.4 million in 2022, and $2.2 million in 2021 and anticipates providing additional funding of $2.1 million in each of the years 2024 and 2025. PNM recovers from retail customers reclamation costs associated with the underground mine. However, the NMPRC capped the amount collected from retail customers for final reclamation of the surface mines at $100.0 million for both SJGS and Four Corners. If future estimates increase the liability for surface mine reclamation, the excess would be expensed at that time. The impacts of changes in New Mexico state law as a result of the enactment of the ETA and regulatory determinations made by the NMPRC may also affect PNM’s financial position, results of operations, and cash flows. See additional discussion regarding PNM’s SJGS and Four Corners Abandonment Applications in Note 17. PNM is currently unable to determine the outcome of these matters or the range of possible impacts. SJGS Decommissioning On November 9, 2021, the San Juan County Commission approved the Coal-Fired Electricity Generating Facility Demolition and Remediation Ordinance (“Ordinance 121”), requiring the full demolition of SJGS upon its complete and permanent closure. Ordinance 121 required the SJGS owners to submit a proposed demolition and remediation plan no later than three months after SJGS was retired. The SJGS owners submitted the decommissioning and remediation plan on December 28, 2022. In connection with restructuring of the SJGS ownership on December 31, 2017, PNM and the other SJGS owners entered into the San Juan Decommissioning and Trust Funds Agreement, which requires PNM to fund its ownership share of final decommissioning costs into an irrevocable trust. Under the agreement, PNM made an initial funding of $14.7 million in December 2022. The amount and timing of additional trust funding is subject to revised decommissioning cost studies and agreement among the SJGS owners. PNM has posted a surety bond in the amount of $46.0 million in connection with certain environmental decommissioning obligations and must maintain the bond or other financial assurance until those obligations are satisfied. The surety bond only represents a liability if the SJGS owners fail to deliver on its contractual liability. For information regarding the impact of Ordinance 121 on PNM’s SJGS decommissioning ARO see Note 15. PNM records its share of the SJGS decommissioning obligation as an ARO on its Consolidated Balance Sheets. Studies on the decommissioning costs of SJGS are performed periodically and revisions to the ARO liability are recorded. In the third quarter of 2022, a new decommissioning cost study was completed, which required PNM to remeasure its SJGS decommissioning ARO. The new study resulted in an estimated decrease to PNM’s share of the decommissioning obligation of $21.1 million, which was recorded in September 2022. Additional information concerning the Company’s SJGS decommissioning ARO is contained in Note 15. PVNGS Liability and Insurance Matters Public liability for incidents at nuclear power plants is governed by the Price-Anderson Nuclear Industries Indemnity Act, which limits the liability of nuclear reactor owners to the amount of insurance available from both commercial sources and an industry-wide retrospective payment plan. The insurance limit is subject to an adjustment every five years based upon the aggregate percentage change in the CPI. The most recent adjustment took effect on October 5, 2023. As of that date, in accordance with this act, the PVNGS participants are insured against public liability exposure for a nuclear incident up to $16.3 billion per occurrence. PVNGS maintains the maximum available nuclear liability insurance in the amount of $500 million, which is provided by American Nuclear Insurers. The remaining $15.8 billion is provided through a mandatory industry-wide retrospective assessment program. If losses at any nuclear power plant covered by the program exceed the accumulated funds, PNM could be assessed retrospective premium adjustments. Based on PNM’s interest in the three PVNGS units, as of December 31, 2023, PNM’s maximum potential retrospective premium assessment per incident for all three units is $37.7 million, with a maximum annual payment limitation of $5.6 million. After the expiration of the PVNGS Unit 1 and 2 leases in January 2023 and January 2024, PNM’s maximum potential retrospective premium assessment per incident for all three units is $36.3 million, with a maximum annual payment limitation of $5.4 million, to be adjusted periodically for inflation. The PVNGS participants maintain insurance for damage to, and decontamination of, property at PVNGS in the aggregate amount of $2.8 billion, a substantial portion of which must first be applied to stabilization and decontamination. These coverages are provided by Nuclear Electric Insurance Limited (“NEIL”). The primary policy offered by NEIL contains a sublimit of $2.25 billion for non-nuclear property damage. If NEIL’s losses in any policy year exceed accumulated funds, PNM is subject to retrospective premium adjustments of $4.9 million. The insurance coverages discussed in this and the previous paragraph are subject to certain policy conditions, sublimits, and exclusions.

Commitments and Contingencies

There are various claims and lawsuits pending against the Company. In addition, the Company is subject to federal, state, and local environmental laws and regulations and periodically participates in the investigation and remediation of various sites. In addition, the Company periodically enters into financial commitments in connection with its business operations. Also, the Company is involved in various legal and regulatory proceedings in the normal course of its business. See Note 17. It is not possible at this time for the Company to determine fully the effect of all litigation and other legal and regulatory proceedings on its financial position, results of operations, or cash flows.

With respect to some of the items listed below, the Company has determined that a loss is not probable or that, to the extent probable, cannot be reasonably estimated. In some cases, the Company is not able to predict with any degree of certainty the range of possible loss that could be incurred. The Company assesses legal and regulatory matters based on current information and makes judgments concerning their potential outcome, giving due consideration to the nature of the claim, the amount and nature of any damages sought, and the probability of success. Such judgments are made with the understanding that the outcome of any litigation, investigation, or other legal proceeding is inherently uncertain. The Company records liabilities for matters where it is probable a loss has been incurred and the amount of loss is reasonably estimatable. The actual

outcomes of the items listed below could ultimately differ from the judgments made and the differences could be material. The Company cannot make any assurances that the amount of reserves or potential insurance coverage will be sufficient to cover the cash obligations that might be incurred as a result of litigation or regulatory proceedings. Except as otherwise disclosed, the Company does not expect that any known lawsuits, environmental costs, or commitments will have a material effect on its financial condition, results of operations, or cash flows.

Commitments and Contingencies Related to the Environment

PVNGS Decommissioning Funding

The costs of decommissioning a nuclear power plant are substantial. PNM is responsible for all decommissioning obligations related to its entire interest in PVNGS, including portions under leases both during and after termination of the leases. PNM has a program for funding its share of decommissioning costs for PVNGS, including portions previously held under leases. The nuclear decommissioning funding program is invested in equities and fixed income instruments in qualified and non-qualified trusts. PNM funded $1.3 million for each of the years ended December 31, 2023, 2022 and 2021 into the qualified trust funds. The fair value of the trusts at December 31, 2023 and 2022 was $361.0 million and $325.3 million. See Note 17 for additional discussion of PNM’s PVNGS Lease Abandonment Application.

Nuclear Spent Fuel and Waste Disposal

Nuclear power plant operators are required to enter into spent fuel disposal contracts with the DOE that require the DOE to accept and dispose of all spent nuclear fuel and other high-level radioactive wastes generated by domestic power reactors. Although the Nuclear Waste Policy Act required the DOE to develop a permanent repository for the storage and disposal of spent nuclear fuel by 1998, the DOE announced that it would not be able to open the repository by 1998 and sought to excuse its performance of these requirements. In November 1997, the DC Circuit issued a decision preventing the DOE from excusing its own delay but refused to order the DOE to begin accepting spent nuclear fuel. Based on this decision and the DOE’s delay, a number of utilities, including APS (on behalf of itself and the other PVNGS owners, including PNM), filed damages actions against the DOE in the Court of Federal Claims. The lawsuits filed by APS alleged that damages were incurred due to DOE’s continuing failure to remove spent nuclear fuel and high-level waste from PVNGS. In August 2014, APS and the DOE entered into a settlement agreement that established a process for the payment of claims for costs incurred through December 31, 2019. APS has accepted the DOE’s extensions of the settlement agreement for recovery of costs incurred through December 31, 2025. Under the settlement agreement, APS must submit claims annually for payment of allowable costs. PNM records estimated claims on a quarterly basis. The benefit from the claims is passed through to customers under the FPPAC.

PNM estimates that it will incur approximately $55.6 million (in 2023 dollars) for its share of the costs related to the on-site interim storage of spent nuclear fuel at PVNGS for the remaining term of the operating licenses. PNM accrues these costs as a component of fuel expense as the nuclear fuel is consumed. At December 31, 2023 and 2022, PNM had a liability for interim storage costs of $11.0 million and $12.0 million, which is included in other deferred credits.

PVNGS has sufficient capacity at its on-site Independent Spent Fuel Storage Installation (“ISFSI”) to store all of the nuclear fuel that will be irradiated during the initial operating license period, which ends in December 2027. Additionally, PVNGS has sufficient capacity at its on-site ISFSI to store a portion of the fuel that will be irradiated during the period of extended operation, which ends in November 2047. If uncertainties regarding the U.S. government’s obligation to accept and store spent fuel are not favorably resolved, APS will evaluate alternative storage solutions that may obviate the need to expand the ISFSI to accommodate all of the fuel that will be irradiated during the period of extended operation.

The Energy Transition Act

In 2019, the Governor signed into New Mexico state law Senate Bill 489, known as the Energy Transition Act (“ETA”). The ETA became effective as of June 14, 2019 and sets a statewide standard that requires investor-owned electric utilities to have specified percentages of their electric-generating portfolios be from renewable and zero-carbon generating resources. The ETA requires utilities operating in New Mexico to have renewable portfolios equal to 40% by 2025, 50% by 2030, 80% by 2040, and 100% zero-carbon energy by 2045. The ETA also allows for the recovery of undepreciated investments and decommissioning costs related to qualifying EGUs that the NMPRC has required be removed from retail jurisdictional rates, provided replacement resources to be included in retail rates have lower or zero-carbon emissions. The ETA requires the NMPRC to review and approve utilities’ annual renewable portfolio plans to ensure compliance with the RPS. The ETA also directs the New Mexico Environmental Improvement Board to adopt standards of performance that limit CO2 emissions to no

more than 1,100 lbs per MWh beginning January 1, 2023 for new or existing coal-fired EGUs with original installed capacities exceeding 300 MW.

The ETA provides for a transition from fossil-fuel generation resources to renewable and other carbon-free resources through certain provisions relating to the abandonment of coal-fired generating facilities. These provisions include the use of energy transition bonds, which are designed to be highly rated bonds that can be issued to finance certain costs of abandoning coal-fired facilities that are retired prior to January 1, 2023 for facilities operated by a “qualifying utility,” or prior to January 1, 2032 for facilities that are not operated by a qualifying utility. The amount of energy transition bonds that can be issued to recover abandonment costs is limited to the lesser of $375.0 million or 150% of the undepreciated investment of the facility as of the abandonment date. Proceeds provided by energy transition bonds must be used only for purposes related to providing utility service to customers and to pay energy transition costs (as defined by the ETA). These costs may include plant decommissioning and coal mine reclamation costs, provided those costs have not previously been recovered from customers or disallowed by the NMPRC or by a court order. Proceeds from energy transition bonds may also be used to fund severances for employees of the retired facility and related coal mine and to promote economic development, education and job training in areas impacted by the retirement of the coal-fired facilities. Energy transition bonds must be issued under a NMPRC approved financing order, are secured by “energy transition property,” are non-recourse to the issuing utility, and are repaid by a non-bypassable charge paid by all customers of the issuing utility. These customer charges are subject to an adjustment mechanism designed to provide for timely and complete payment of principal and interest due under the energy transition bonds.

The ETA also provides that utilities must obtain NMPRC approval of competitively procured replacement resources that shall be evaluated based on their cost, economic development opportunity, ability to provide jobs with comparable pay and benefits to those lost upon retirement of the facility and that do not exceed emissions thresholds specified in the ETA. In determining whether to approve replacement resources, the NMPRC must give preference to resources with the least environmental impacts, those with higher ratios of capital costs to fuel costs, and those located in the school district of the abandoned facility. The ETA also provides for the procurement of energy storage facilities and gives utilities discretion to maintain, control, and operate these systems to ensure reliable and efficient service.

The ETA has had and will have a significant impact on PNM’s future generation portfolio, including PNM’s retirement of SJGS in 2022 and the exit of Four Corners (subject to regulatory approval). PNM cannot predict the full impact of the ETA or the outcome of its pending and potential future generating resource abandonment and replacement resource filings with the NMPRC. See additional discussion in Note 17 of PNM’s SJGS and Four Corners Abandonment Applications.

Pursuant to the CAA, states are required to establish goals for improving visibility in national parks and wilderness areas (also known as Class I areas) and to develop long-term strategies for reducing emissions of air pollutants that cause visibility impairment in their own states and for preventing degradation in other states. States must establish a series of interim goals to ensure continued progress by adopting a new SIP every ten years. In the first SIP planning period, states were required to conduct BART determinations for certain covered facilities, including utility boilers, built between 1962 and 1977 that have the potential to emit more than 250 tons per year of visibility impairing pollution. For all future SIP planning periods, states must evaluate whether additional emissions reduction measures may be needed to continue making reasonable progress toward natural visibility conditions.

In 2017, EPA published revisions to the regional haze rule in the Federal Register that delayed the due date for the next cycle of SIPs from 2019 to 2021 and altered the planning process that states must employ in determining whether to impose “reasonable progress” emission reduction measures. EPA’s new rule was challenged by numerous parties, but the litigation was held in abeyance after EPA granted various petitions for reconsideration.

In 2018, EPA released a new guidance document on tracking visibility progress for the second planning period. EPA is allowing states discretion to develop SIPs that may differ from EPA’s guidance as long as they are consistent with the CAA and other applicable regulations. In 2019, EPA finalized the draft guidance that was previously released as a companion to the regional haze rule revisions, and EPA clarified that guidance in a memorandum issued in 2021.

SIPs for the second planning period were due in July 2021, which deadline NMED was unable to meet. NMED is currently preparing its SIP for the second compliance period and has notified PNM that it will not be required to submit a regional haze four-factor analysis for SJGS since PNM retired its share of SJGS in 2022. On August 30, 2022, EPA published in the Federal Register an official “Finding of Failure to Submit” for states, including New Mexico, that have not yet submitted

a round 2 regional haze SIP. This action by EPA starts a 2-year clock for it to issue a Federal Implementation Plan (FIP). NMED’s current timeline indicates the proposed SIP will be submitted to EPA by Summer 2024.

Carbon Dioxide Emissions

In 2015, EPA established standards to limit CO2 emissions from power plants, including (1) Carbon Pollution Standards for new, modified, and reconstructed power plants; and (2) the Clean Power Plan for existing power plants.

Multiple states, utilities, and trade groups challenged both the Carbon Pollution Standards for new sources and the Clean Power Plan for existing sources in separate cases. Challengers successfully petitioned the US Supreme Court for a stay of the Clean Power Plan. However, before the DC Circuit could issue an opinion regarding either the Carbon Pollution Standards or the Clean Power Plan, the Trump Administration asked that the case be held in abeyance while the rules were reevaluated, which was granted.

In 2019, EPA repealed the Clean Power Plan, promulgated the ACE Rule, and revised the implementing regulations for all emission guidelines. EPA set the BSER for existing coal-fired power plants as heat rate efficiency improvements based on a range of “candidate technologies” that can be applied inside the fence line of an individual facility. The DC Circuit issued an order that granted motions by various petitioners, including industry groups and EPA, to dismiss the cases challenging the Clean Power Plan as moot due to EPA’s issuance of the ACE Rule.

The ACE Rule was also challenged, and on January 19, 2021, the DC Circuit issued an opinion in American Lung Association and American Public Health Association v. EPA, et al., vacating the ACE Rule. While the DC Circuit rejected the ACE Rule, it did not reinstate the Clean Power Plan. Rather, the DC Circuit granted an EPA motion asking the court to withhold issuance of the mandate with respect to the repeal of the Clean Power Plan until EPA responds to the court’s remand in a new rulemaking action.

Numerous parties sought review by the US Supreme Court, and on June 30, 2022, the Court held that the “generation shifting” approach in the Clean Power Plan exceeded the powers granted to EPA by Congress, though the Court did not address the related issue of whether Section 111 of the CAA only authorizes EPA to require measures that can be implemented entirely within the fence line at an individual source. Of broader significance in administrative law, the Court’s opinion expressly invoked the “major question” doctrine, which requires rules involving issues of “vast economic or political significance” to be supported by clear statutory authorization. In cases where there is no clear statement of authority, courts need not defer to the agency’s statutory interpretation on “major questions.” The decision sets legal precedent for future rulemakings by EPA and other federal regulatory agencies whereby the agencies’ authority may be limited based upon similar reasoning.

The litigation over the Carbon Pollution Standards remains held in abeyance but could be reactivated by the parties upon a determination by the court that reconsideration of the rule has concluded.

On May 23, 2023, EPA published in the Federal Register proposed regulatory actions under CAA sections 111(b) and (d) to replace the Clean Power Plan and the ACE Rule. The proposed regulations cover: (1) New natural gas-based EGUs under section 111(b); (2) Existing large and frequently operated natural gas-based EGUs under section 111(d); and (3) Existing coal-based EGUs under section 111(d). Standards of performance for existing coal EGUs will be based on two technologies depending on retirement date: carbon capture and storage/sequestration (“CCS”) or co-firing gas in lieu of coal. For gas-based EGUs, the standards will be based on CCS or the use of green hydrogen in lieu of natural gas. States will be required to develop SIPs to EPA that provide for the establishment, implementation and enforcement of these standards as they apply to existing sources. States may take into account remaining useful life and other factors when establishing the standards. EPA is proposing that existing coal units must start complying with their gas co-firing or CCS based standards of performance on January 1, 2030, unless they commit to retirement before 2032 (or retirement by 2035 if they also commit to a 20% annual operating limit). Existing combustion turbine units must start complying with their hydrogen or CCS based standards of performance on January 1, 2032, or January 1, 2035, depending on their subcategory, which is based on the control technology selected. The package also includes a proposed repeal of the ACE rule and revisions to the standard for modified and reconstructed units, along with a notice of public rulemaking seeking data and information about setting standards for existing smaller natural gas-based generators. Comments on the rule were due to EPA by August 8, 2023. PNM filed company-specific comments and continues to review the proposed rule and its potential impacts on the company’s fossil generation resources. EPA has indicated it plans to promulgate a final rule by Spring 2024.

On January 27, 2021, President Biden signed an extensive Executive Order aimed at addressing climate change concerns domestically and internationally. The order is intended to build on the initial climate-related actions the Biden

Administration took on January 20, 2021. It addresses a wide range of issues, including establishing climate change concerns as an essential element of U.S. foreign and security policy, identifying a process to determine the U.S. INDC under the Paris Agreement, and establishing a Special Presidential Envoy for Climate that will sit on the National Security Council. On April 22, 2021, at the Earth Day Summit, as part of the U.S.’s re-entry into the Paris Agreement, President Biden unveiled the goal to cut U.S. emissions by 50% - 52% from 2005 levels by 2030, nearly double the GHG emissions reduction target set by the Obama Administration. The 2030 goal joins President Biden’s other climate goals which include a carbon pollution-free power sector by 2035 and a net-zero emissions economy by no later than 2050.

PNM’s review of the GHG emission reductions standards that may occur as a result of legislation or regulation under the Biden Administration and in response to the court’s ruling on the ACE Rule is ongoing. PNM cannot predict the impact these standards may have on its operations or a range of the potential costs of compliance, if any.

National Ambient Air Quality Standards (“NAAQS”)

The CAA requires EPA to set NAAQS for pollutants reasonably anticipated to endanger public health or welfare. EPA has set NAAQS for certain pollutants, including NOx, SO2, ozone, and particulate matter.

NOX Standard – In 2018, EPA published the final rule to retain the current primary health-based NOx standards of which NO2 is the constituent of greatest concern and is the indicator for the primary NAAQS. EPA concluded that the current 1-hour and annual primary NO2 standards are requisite to protect public health with an adequate margin of safety. The rule became effective on May 18, 2018. The State of New Mexico has attained the current NOx NAAQS standards.

SO2 Standard – In 2019, EPA announced its final decision to retain, without changes, the primary health-based NAAQS for SO2. Specifically, EPA will retain the current 1-hour standard for SO2, which is 75 parts per billion, based on the 3-year average of the 99th percentile of daily maximum 1-hour SO2 concentrations.

On March 26, 2021, EPA published in the Federal Register the initial air quality designations for all remaining areas not yet designated under the 2010 SO2 Primary NAAQS. All areas of New Mexico have been designated attainment/unclassifiable through four rounds of designations by EPA.

Ozone Standard – In 2015, EPA finalized the new ozone NAAQS and lowered both the primary and secondary 8-hour standard from 75 to 70 parts per billion. With ozone standards becoming more stringent, fossil-fueled generation units will come under increasing pressure to reduce emissions of NOx and volatile organic compounds since these are the pollutants that form ground-level ozone. On July 13, 2020, EPA proposed to retain the existing ozone NAAQS based on a review of the full body of currently available scientific evidence and exposure/risk information. EPA finalized its decision to retain the ozone NAAQS in a notice published on December 31, 2020 making it immediately effective. In response to lawsuits brought by states and environmental groups, on October 29, 2021, EPA filed a motion in the DC Circuit indicating it will reconsider the 2020 ozone NAAQS. On August 21, 2023, EPA announced an entirely new review of the ozone standard that will incorporate the work to date on the reconsideration, likely indicating a delay in the schedule for a decision on whether the standard should be revised. On January 3, 2024, EPA filed in the DC Circuit an unopposed motion for voluntary remand, without vacatur, of EPA’s final rule retaining the current ozone NAAQS. The filing was made in the consolidated cases challenging the 2020 ozone NAAQS rule.

During 2017 and 2018, EPA released rules establishing area designations for ozone. In those rules, San Juan County, New Mexico, where Four Corners is located, is designated as attainment/unclassifiable and only a small area in Doña Ana County, New Mexico is designated as marginal non-attainment. Although Afton Generating Station is located in Doña Ana County, it is not located within the small area designated as non-attainment for the 2015 ozone standard. The rule became effective May 8, 2018.

NMED has responsibility for bringing the small area in Doña Ana County designated as marginal/non-attainment for ozone into compliance and will look at all sources of NOx and volatile organic compounds. NMED has submitted the required elements for the Sunland Park Ozone Non-attainment Area SIP. This includes a transportation conformity demonstration, a 2017 baseline emissions inventory and emissions statement, and an amendment to the state’s Non-attainment Permitting rules at 20.2.79 New Mexico Administrative Code to conform to EPA’s SIP Requirements Rule for 2015 Q3 NAAQS (i.e., “implementation rule”).

The SIP elements had staggered deadlines and were done in three submissions: (1) the transportation conformity demonstration was completed by the El Paso Metropolitan Planning Organization on behalf of New Mexico in 2019, which is responsible for transportation planning in that area, and the submission received concurrence from EPA and the Federal

Highway Administration; (2) the emissions inventory and statement SIP was submitted to EPA in September 2020; and (3) the Non-attainment New Source Review SIP was submitted to EPA on August 10, 2021. On October 15, 2021, EPA proposed to approve New Mexico’s SIP to meet the emissions inventory and statement requirements of the CAA for the Sunland Park Ozone Non-Attainment Area.

PNM does not believe there will be material impacts to its facilities because of NMED’s non-attainment designation of the small area within Doña Ana County. Until EPA approves attainment designations for the Navajo Nation and releases a proposal to implement the revised ozone NAAQS, PNM is unable to predict what impact the adoption of these standards may have on Four Corners. With respect to EPA’s reconsideration of the 2020 decision to retain the 2015 ozone standards, EPA is statutorily obligated to complete its review of the ozone standards by December 2025. PNM cannot predict the outcome of this matter.

In 2019, EPA issued findings that several states, including New Mexico, had failed to submit interstate transport SIPs for the 2015 8-hour ozone NAAQS, triggering an obligation for EPA to issue a federal implementation plan within two years. In response, NMED submitted a Good Neighbor SIP on July 27, 2021 that demonstrates that there are no significant contributions from New Mexico to downwind problems in meeting the federal ozone standard. Nevertheless, when EPA failed to approve the SIP or issue a FIP within two years of the finding of failure to submit, multiple parties filed a deadline suit against EPA, resulting in a consent decree requiring EPA to issue a FIP or approve a SIP for New Mexico by a deadline of no later than June 1, 2024, which was later extended to August 30, 2024. On March 15, 2023, EPA Administrator Regan signed a final action imposing a FIP on multiple states but did not include a FIP for New Mexico because EPA had not proposed a FIP for the state because the most up to date modeling available at proposal confirmed the state did not contribute to downwind ozone nonattainment or maintenance areas. However, the updated modeling EPA used in the final rule indicated that New Mexico may be significantly contributing to one or more non-attainment or maintenance areas. In light of that modeling result, on February 16, 2024, EPA proposed to impose a FIP on New Mexico to address the newly identified contribution. If finalized as proposed, the FIP would require specified fossil fuel-fired generating resources to participate in an ozone-season NOx emission allowance trading program that will limit total NOx emissions from all affected units within the state of New Mexico.

PM Standard – On January 30, 2020, EPA published in the Federal Register a notice announcing the availability of a final Policy Assessment for the Review of the NAAQS for Particulate Matter (the “PA”). The 2020 final PA was prepared as part of the review of the primary and secondary PM NAAQS. In the 2020 final PA, EPA recommended lowering the primary annual PM 2.5 standard to between 8 µg/m3 and 10 µg/m3. However, on April 30, 2020, EPA published a proposed rule to retain the current standards for PM due to uncertainties in the data relied upon in the 2020 final PA and EPA published a notice of that final action on December 18, 2020, making it immediately effective. On January 14, 2021, several states and New York City filed a petition for review in the DC Circuit, challenging EPA’s final rule retaining the current primary and secondary PM NAAQS and a similar lawsuit was filed by the Center for Biological Diversity in the DC Circuit. On June 10, 2021, EPA announced that it will reconsider the previous administration’s December 2020 decision to retain the current primary and secondary PM NAAQS and on October 8, 2021, EPA announced the release of a new draft PA stating that available scientific evidence and technical information indicate that the current standards may not be adequate to protect public health and welfare, as required by the CAA. On June 1, 2022, EPA issued a new final PA that likewise indicates current standards may not be adequate and that available scientific evidence could support lowering the standards.

On January 27, 2023, EPA published, in the Federal Register, a proposal to lower the annual fine PM standard to between 9-10 µg/m3 but retain the rest of its PM standards, including the current daily fine particulate matter standard, the daily coarse particulate matter standard, and the secondary PM standards. EPA issued a prepublication of the final rule on February 7, 2024, lowering the fine PM standard to 9 ug/m3. Although the lower standard is expected to result in new nonattainment areas throughout the country and could prompt additional PM control requirements, PNM cannot predict the impacts of the outcome of future rulemaking.

Cooling Water Intake Structures

In 2014, EPA issued a rule establishing national standards for certain cooling water intake structures at existing power plants and other facilities under the Clean Water Act to protect fish and other aquatic organisms by minimizing impingement mortality (the capture of aquatic wildlife on intake structures or against screens) and entrainment mortality (the capture of fish or shellfish in water flow entering and passing through intake structures).

To minimize impingement mortality, the rule provides operators of facilities, such as Four Corners, seven options for meeting Best Technology Available (“BTA”) standards for reducing impingement. The permitting authority must establish the BTA for entrainment on a site-specific basis, taking into consideration an array of factors, including endangered species and

social costs and benefits. Affected sources must submit source water baseline characterization data to the permitting authority to assist in the determination. Compliance deadlines under the rule are tied to permit renewal and will be subject to a schedule of compliance established by the permitting authority.

In 2018, several environmental groups sued EPA Region IX in the U.S. Court of Appeals for the Ninth Circuit Court over EPA’s failure to timely reissue the Four Corners NPDES permit. The petitioners asked the court to issue a writ of mandamus compelling EPA Region IX to take final action on the pending NPDES permit by a reasonable date. EPA subsequently reissued the NPDES permit. The permit did not contain conditions related to the cooling water intake structure rule, as EPA determined that the facility has achieved BTA for both impingement and entrainment by operating a closed-cycle recirculation system. Several environmental groups filed a petition for review with EPA’s Environmental Appeals Board (“EAB”) concerning the reissued permit. The environmental groups alleged that the permit was reissued in contravention of several requirements under the Clean Water Act and did not contain required provisions concerning certain revised ELG, existing-source regulations governing cooling-water intake structures, and effluent limits for surface seepage and subsurface discharges from coal-ash disposal facilities. EPA withdrew the Four Corners NPDES permit in order to examine issues raised by the environmental groups. Withdrawal of the permit moots the appeal pending before the EAB. EAB thereafter dismissed the environmental groups’ appeal. EPA issued an updated NPDES permit in 2019. The permit was once again appealed to the EAB and was stayed before the effective date. Oral argument was heard on September 3, 2020. The EAB issued an order denying the petition for review on September 30, 2020. The denial was based on the EAB’s determination that the petitioners had failed to demonstrate that review of the permit was warranted on any of the grounds presented in the petition. Thereafter, the Regional Administrator of the EPA signed a notice of final permit decision, and the NPDES permit was issued on November 9, 2020. The permit became effective December 1, 2020 and will expire on November 30, 2025. On January 22, 2021, the environmental groups filed a petition for review of the EAB’s decision with the U.S. Court of Appeals for the Ninth Circuit. The September 2019 permit remains in effect pending this appeal. On March 21, 2022, EPA provided notice in the Federal Register of a proposed settlement agreement with the environmental groups. The parties subsequently executed the settlement agreement as of May 2, 2022. Under the settlement, the associated case was administratively closed through September 6, 2023, during which time a third-party consultant spent 12 months sampling discharges from Four Corners and EPA spent three months completing an analysis. On December 1, 2023, EPA issued a modification, effective December 31, 2023, to the NPDES permit issued on November 9, 2020. The modification applies to permit elements related to effluent discharge. PNM cannot predict whether the analysis under the settlement agreement will result in changes to the NPDES permit but does not anticipate that it will have a material impact on PNM’s financial position, results of operations, or cash flows.

Effluent Limitation Guidelines

In 2013, EPA published proposed revised wastewater ELG establishing technology-based wastewater discharge limitations for fossil fuel-fired electric power plants. EPA signed the final Steam Electric ELG rule in 2015. The final rule, which became effective on January 4, 2016, phased in the new, more stringent requirements in the form of effluent limits for arsenic, mercury, selenium, and nitrogen for wastewater discharged from wet scrubber systems and zero discharge of pollutants in ash transport water that must be incorporated into plants’ NPDES permits. The 2015 rule required each plant to comply between 2018 and 2023 depending on when it needs a new or revised NPDES permit.

The Steam Electric ELG rule was challenged in the U.S. Court of Appeals for the Fifth Circuit by numerous parties. In 2017, EPA signed a notice indicating its intent to reconsider portions of the rule, and the Fifth Circuit issued an order severing the issues under reconsideration and holding the case in abeyance as to those issues. However, the court allowed challenges to other portions of the rule to proceed. In 2019, the Fifth Circuit granted those challenges and issued an opinion vacating several portions of the rule, specifically those related to legacy wastewater and leachate, for which the court deemed the standards selected by EPA arbitrary and capricious.

In 2017, EPA published a final rule for postponement of certain compliance dates. The rule postponed the earliest date on which compliance with the ELG for these waste streams would be required from November 1, 2018 until November 1, 2020. In 2019, EPA published a proposed rule revising the original ELG while maintaining the compliance dates. In 2020, EPA published in the Federal Register the final Steam Electric ELG and standards for the Steam Electric Power Generating Point Source Category, revising the final 2015 guidelines for both flue gas desulfurization wastewater and bottom ash transport water. The rule requires compliance with new limits as soon as possible on or after October 13, 2021, but no later than December 31, 2025.

On August 3, 2021, EPA published notice that it will undertake a supplemental rulemaking to revise the ELG after completing its review of the rules reconsidered in 2020. As part of this process, EPA will determine whether more stringent limitations and standards are appropriate. On March 29, 2023, EPA published the proposed ELG Rule in the Federal Register.

The proposed rule includes stricter limitations on bottom ash transport water, flue gas desulfurization, and coal combustion residual leachate. Also included are flexibilities for coal-powered facilities that will soon decommission or repower. With this proposed rule EPA has extended the date of decommissioning or repowering from December 31, 2028, to December 31, 2032. Comments on the proposed rule were due May 30, 2023. A final rule is expected in April 2024.

Reeves Station discharges cooling tower blowdown to a publicly owned treatment plant and no longer holds an NPDES permit; therefore, it is expected that no requirements will be imposed.

See “Cooling Water Intake Structures” above for additional discussion of Four Corners’ current NPDES permit. Four Corners may be required to change equipment and operating practices affecting boilers and ash handling systems, as well as change its waste disposal techniques during the next NPDES permit renewal in 2023. PNM is unable to predict the outcome of these matters or a range of the potential costs of compliance.

Santa Fe Generating Station

PNM and NMED are parties to agreements under which PNM has installed a remediation system to treat water from a City of Santa Fe municipal supply well and an extraction well to address gasoline contamination in the groundwater at the site of PNM’s former Santa Fe Generating Station and service center. A 2008 NMED site inspection report states that neither the source nor extent of contamination at the site has been determined and that the source may not be the former Santa Fe Generating Station. During 2013 and 2014, PNM and NMED collected additional samples that showed elevated concentrations of nitrate and volatile organic compounds in some of the monitoring wells at the site. In addition, one monitoring well contained free-phase hydrocarbon products. PNM collected a sample of the product for “fingerprint” analysis. The results of this analysis indicated the product was a mixture of older and newer fuels. The presence of newer fuels in the sample suggests the hydrocarbon product likely originated from off-site sources. In 2015, PNM and NMED entered into a memorandum of understanding to address changing groundwater conditions at the site under which PNM agreed to continue hydrocarbon investigation under the supervision of NMED. Qualified costs are eligible for payment through the New Mexico Corrective Action Fund (“CAF”), which is administered by the NMED Petroleum Storage Tank Bureau. In 2019, PNM received notice from NMED that an abatement plan for the site is required to address concentrations of previously identified compounds, unrelated to those discussed above, found in the groundwater. NMED approved PNM’s abatement plan proposal, which covers field work and reporting.

Field work related to the investigation under both the CAF and abatement plan requirements was completed and activities and findings associated with the field work were presented in two separate reports and released to stakeholders in early 2020. Subsequent field work was completed in July 2020 and two reports were released supporting PNM’s contention that off-site sources have impacted, and are continuing to impact, the local groundwater in the vicinity of the former Santa Fe Generating Station.

PNM submitted work plans to NMED in January 2021 for review and approval. In December 2021, NMED approved both work plans and work activities were completed by the end of 2022. A report was submitted to the NMED in the first quarter of 2023.

Groundwater sampling for the abatement plan’s first semiannual work commenced at the beginning of March 2023 and was completed in April 2023. The associated report was completed and submitted to the NMED in July 2023. In addition, the work plan for the 2023 CAF work was completed and submitted to the NMED in July 2023. NMED approved the work plan in December 2023 and PNM is working to schedule the associated activities.

The City of Santa Fe has stopped operating its well at the site, which is needed for PNM’s groundwater remediation system to operate. As a result, PNM has stopped performing remediation activities at the site. However, PNM’s monitoring and other abatement activities at the site are ongoing and will continue until the groundwater meets applicable federal and state standards or until the NMED determines remediation is not required, whichever is earlier. PNM is not able to assess the duration of this project or estimate the impact on its obligations if PNM is required to resume groundwater remediation activities at the site. PNM is unable to predict the outcome of these matters.

Coal Combustion Residuals Waste Disposal

CCRs consisting of fly ash, bottom ash, and gypsum generated from coal combustion and emission control equipment at SJGS are currently disposed of in the surface mine pits adjacent to the plant. SJGS does not operate any CCR impoundments or landfills. The NMMMD currently regulates mine reclamation activities at the San Juan mine, including placement of CCRs in

the surface mine pits, with federal oversight by the OSM. APS disposes of CCRs in ponds and dry storage areas at Four Corners. Ash management at Four Corners is regulated by EPA and the New Mexico State Engineer’s Office.

EPA’s final coal ash rule, which became effective in 2015, included a non-hazardous waste determination for coal ash and sets minimum criteria for existing and new CCR landfills and surface impoundments. In 2016, the Water Infrastructure Improvements for the Nation Act (the “WIIN Act”) was signed into law to address critical water infrastructure needs in the U.S. and contains a number of provisions related to the CCR rules. Among other things, the WIIN Act allows, but does not require, states to develop and submit CCR permit programs for EPA approval, provides flexibility for states to incorporate EPA’s final rule for CCRs or develop other criteria that are at least as protective as EPA’s final rule, and requires EPA to approve state permit programs within 180 days of submission by the state. Because states are not required to implement their own CCR permit programs, EPA will implement the permit program in states that choose not to implement a program, subject to Congressional funding. Until permit programs are in effect, EPA has authority to directly enforce the CCR rule. For facilities located within the boundaries of Native American reservations, such as the Navajo Nation where Four Corners is located, EPA is required to develop a federal permit program regardless of appropriated funds.

In 2018, EPA published a rule that constitutes “Phase One, Part One” of its ongoing reconsideration and revision of the April 17, 2015, CCR rule. The final Phase One, Part One rule includes two types of revisions. The first revision extended the deadline to allow EGUs with unlined impoundments or that fail to meet the uppermost aquifer requirement to continue to receive coal ash until October 31, 2020. This deadline was again extended by subsequent amendments. The rule also authorized a “Participating State Director” or EPA to approve suspension of groundwater monitoring requirements and to issue certifications related to the location restrictions, design criteria, groundwater monitoring, remedy selection and implementation. The rule also modified groundwater protection standards for certain constituents, which include cobalt, molybdenum, lithium, and lead without a maximum contamination level.

In 2019, EPA published a second round of revisions, which are commonly referred to as the “Phase Two” revisions. Phase Two proposed revisions to reporting and accessibility to public information, the “CCR piles” and “beneficial use” definitions and the requirements for management of CCR piles. EPA has reopened and extended the Phase Two comment period several times. EPA has not yet finalized provisions in Phase Two related to beneficial use of CCR and CCR piles. This activity is on EPA’s long-term agenda, which means EPA has no plans to address these issues in the next 12 months.

Since promulgating its Phase Two proposal, EPA has finalized two other rules addressing various CCR rule provisions. In 2019, EPA promulgated its proposed Holistic Approach to Closure Part A (“Part A”), which proposed a new deadline of August 31, 2020, for companies to initiate closure of unlined CCR impoundments. In accordance with the DC Circuit Court of Appeals’ vacatur of portions of the CCR Rule, Part A also proposed changing the classification of compacted soil-lined or clay-lined surface impoundments from “lined” to “unlined”. In addition, Part A delineated a process for owners/operators to submit requests for alternative closure deadlines based on lack of alternate disposal capacity. EPA issued the final Part A, which became effective on September 28, 2020. This rule finalized the classification of soil-lined and clay-lined surface impoundments as unlined, thus, triggering closure or retrofit requirements for those impoundments. The final Part A also gave operators of unlined impoundments until April 11, 2021 to cease receipt of waste at these units and initiate closure.

In 2020, EPA issued the proposed Holistic Approach to Closure Part B (“Part B”), which delineated the process for owners/operators to submit alternate liner demonstrations for clay-lined surface impoundments that could otherwise meet applicable requirements. Part B also proposed regulations addressing beneficial use for closure of surface impoundments. EPA issued the final Part B rule, which became effective on December 14, 2020. This rule did not include beneficial use of CCR for closure, which EPA explains will be addressed in subsequent rulemaking actions. On May 18, 2023, EPA published a proposed rule on the regulatory requirements for inactive surface impoundments at inactive facilities including groundwater monitoring, corrective action, closure, and post-closure care requirements for all CCR management units (regardless of how or when that CCR was placed), and several technical corrections to the existing regulations. Comments on the proposed rule were due July 17, 2023. A final rule is expected April 2024. EPA intends to issue other rulemakings and finalizing parts of previously proposed rules, including a final rule in October 2024 on remaining Part B issues regarding closure options and annual reporting.

In 2020, EPA published a proposed rule establishing a federal permitting program for the handling of CCR within the boundaries of Native American reservations and in states without their own federally authorized state programs. Permits for units within the boundaries of Native American reservations would be due 18 months after the effective date of the rule. According to the Fall 2023 Regulatory Agenda the final rule is expected in March 2026. EPA is coordinating with the affected permits for the three facilities with CCR disposal units located on Native American lands. PNM cannot predict the outcome of

EPA’s rulemaking activity or the outcome of any related litigation, and whether or how such a ruling would affect operations at Four Corners.

The CCR rule does not cover mine placement of coal ash. OSM is expected to publish a proposed rule covering mine placement in the future and will likely be influenced by EPA’s rule and the determination by EPA that CCRs are non-hazardous. PNM cannot predict the outcome of OSM’s proposed rulemaking regarding CCR regulation, including mine placement of CCRs, or whether OSM’s actions will have a material impact on PNM’s operations, financial position, or cash flows. Based upon the requirements of the final Part A CCR rule, PNM conducted a CCR assessment at SJGS and made minor modifications at the plant to ensure that there are no facilities that would be considered impoundments or landfills under the rule. PNM would seek recovery from its retail customers of all CCR costs for jurisdictional assets that are ultimately incurred.

Utilities that own or operate CCR disposal units, such as those at Four Corners, as indicated above, were required to collect sufficient groundwater sampling data to initiate a detection monitoring program. Four Corners completed the analysis for its CCR disposal units, which identified several units that needed corrective action or needed to cease operations and initiate closure by April 11, 2021. Work is ongoing. Four Corners continues to gather additional groundwater data and perform remedial evaluations and activities. At this time, PNM does not anticipate its share of the cost to complete these corrective actions to close the CCR disposal units, or to gather and perform remedial evaluations on groundwater at Four Corners, will have a significant impact on its operations, financial position, or cash flows.

Other Commitments and Contingencies

The coal requirements for SJGS were supplied by WSJ LLC. Pricing under the SJGS CSA was primarily fixed, with adjustments to reflect changes in general inflation. Substantially all of SJGS’s coal costs were passed through the FPPAC. See additional discussion of PNM’s SJGS Abandonment Application Note 17.

APS purchases all of Four Corners’ coal requirements from NTEC, an entity owned by the Navajo Nation, under the Four Corners CSA that expires in 2031. The coal comes from reserves located within the Navajo Nation. The contract provides for pricing adjustments over its term based on economic indices and includes certain minimum payments that may be required if no deliveries of coal are taken. As of December 31, 2023 those minimum payments were $39.9 million for 2024, $81.8 million for 2025 and 2026, $83.8 million for 2027 and 2028, and $111.6 million for 2029 and thereafter. PNM’s share of the coal costs is being recovered through the FPPAC.

Coal Mine Reclamation

As indicated under Coal Combustion Residuals Waste Disposal above, SJGS disposed of CCRs in the surface mine pits adjacent to the plant and Four Corners disposes of CCRs in ponds and dry storage areas.

Under the terms of the SJGS CSA, PNM and the other SJGS owners are obligated to compensate WSJ LLC for all reclamation costs associated with the supply of coal from the San Juan mine. PNM and Westmoreland have entered into an agreement under which mine reclamation services for SJGS would be provided. In 2020, a mine reclamation cost study was completed for the mine that serves SJGS. PNM’s estimate of the costs necessary to reclaim the mine that serves SJGS is subject to many assumptions, including the timing of reclamation, generally accepted practices at the time reclamation activities occur, and current inflation and discount rates. PNM cannot predict the ultimate cost to reclaim the mine that serves SJGS and would seek to recover all costs related to reclaiming the underground mine from its customers but could be exposed to additional loss related to surface mine reclamation. Additionally, in connection with certain mining permits relating to the operation of the San Juan mine, Westmoreland was required to post reclamation bonds of $118.7 million with the NMMMD. In order to facilitate the posting of reclamation bonds by sureties on behalf of Westmoreland, PNMR entered into the WFB LOC Facility under which letters of credit aggregating $30.3 million have been issued.

A coal mine reclamation study for the mine that serves Four Corners was issued in 2019. The study reflected operation of the mine through 2031, the term of the Four Corners CSA. As discussed in Note 17, PNM remains responsible for its share of costs associated with mine reclamation under the Four Corners Purchase and Sale Agreement with NTEC. The Company is evaluating the facts and circumstances surrounding the exit of Four Corners and will determine next steps.

Based on the most recent estimates, PNM’s remaining payments for mine reclamation, in future dollars, are estimated to be $53.6 million for the surface mines at both SJGS and Four Corners and $30.4 million for the underground mine at SJGS as of December 31, 2023. At December 31, 2023 and 2022, liabilities, in current dollars, of $50.0 million and $62.6 million for surface mine reclamation and $26.2 million and $28.2 million for underground mine reclamation were recorded in other deferred credits.

The SJGS owners entered into a reclamation trust funds agreement to provide funding to compensate WSJ LLC for post-term reclamation obligations. The trust funds agreement requires each owner to enter into an individual trust agreement with a financial institution as trustee, create an irrevocable reclamation trust, and periodically deposit funds into the reclamation trust for the owner’s share of the mine reclamation obligation. Deposits, which are based on funding curves, must be made on an annual basis. PNM funded $2.7 million in 2023, $10.0 million in 2022, and $5.2 million in 2021. Based on PNM’s reclamation trust fund balance at December 31, 2023, the current funding curves indicate PNM’s required contributions to its reclamation trust fund would be zero in each of the years 2024, 2025, and 2026.

Under the Four Corners CSA, PNM is required to fund its share of estimated final reclamation costs in annual installments into an irrevocable escrow account solely dedicated to the final reclamation cost of the surface mine at Four Corners. PNM contributed $0.2 million in 2023, $2.4 million in 2022, and $2.2 million in 2021 and anticipates providing additional funding of $2.1 million in each of the years 2024 and 2025.

PNM recovers from retail customers reclamation costs associated with the underground mine. However, the NMPRC capped the amount collected from retail customers for final reclamation of the surface mines at $100.0 million for both SJGS and Four Corners. If future estimates increase the liability for surface mine reclamation, the excess would be expensed at that time. The impacts of changes in New Mexico state law as a result of the enactment of the ETA and regulatory determinations made by the NMPRC may also affect PNM’s financial position, results of operations, and cash flows. See additional discussion regarding PNM’s SJGS and Four Corners Abandonment Applications in Note 17. PNM is currently unable to determine the outcome of these matters or the range of possible impacts.

SJGS Decommissioning

On November 9, 2021, the San Juan County Commission approved the Coal-Fired Electricity Generating Facility Demolition and Remediation Ordinance (“Ordinance 121”), requiring the full demolition of SJGS upon its complete and permanent closure. Ordinance 121 required the SJGS owners to submit a proposed demolition and remediation plan no later than three months after SJGS was retired. The SJGS owners submitted the decommissioning and remediation plan on December 28, 2022. In connection with restructuring of the SJGS ownership on December 31, 2017, PNM and the other SJGS owners entered into the San Juan Decommissioning and Trust Funds Agreement, which requires PNM to fund its ownership share of final decommissioning costs into an irrevocable trust. Under the agreement, PNM made an initial funding of $14.7 million in December 2022. The amount and timing of additional trust funding is subject to revised decommissioning cost studies and agreement among the SJGS owners. PNM has posted a surety bond in the amount of $46.0 million in connection with certain environmental decommissioning obligations and must maintain the bond or other financial assurance until those obligations are satisfied. The surety bond only represents a liability if the SJGS owners fail to deliver on its contractual liability. For information regarding the impact of Ordinance 121 on PNM’s SJGS decommissioning ARO see Note 15.

PNM records its share of the SJGS decommissioning obligation as an ARO on its Consolidated Balance Sheets. Studies on the decommissioning costs of SJGS are performed periodically and revisions to the ARO liability are recorded. In the third quarter of 2022, a new decommissioning cost study was completed, which required PNM to remeasure its SJGS decommissioning ARO. The new study resulted in an estimated decrease to PNM’s share of the decommissioning obligation of $21.1 million, which was recorded in September 2022. Additional information concerning the Company’s SJGS decommissioning ARO is contained in Note 15.

PVNGS Liability and Insurance Matters

Public liability for incidents at nuclear power plants is governed by the Price-Anderson Nuclear Industries Indemnity Act, which limits the liability of nuclear reactor owners to the amount of insurance available from both commercial sources and an industry-wide retrospective payment plan. The insurance limit is subject to an adjustment every five years based upon the aggregate percentage change in the CPI. The most recent adjustment took effect on October 5, 2023. As of that date, in accordance with this act, the PVNGS participants are insured against public liability exposure for a nuclear incident up to $16.3 billion per occurrence. PVNGS maintains the maximum available nuclear liability insurance in the amount of $500 million, which is provided by American Nuclear Insurers. The remaining $15.8 billion is provided through a mandatory industry-wide retrospective assessment program. If losses at any nuclear power plant covered by the program exceed the accumulated funds,

PNM could be assessed retrospective premium adjustments. Based on PNM’s interest in the three PVNGS units, as of December 31, 2023, PNM’s maximum potential retrospective premium assessment per incident for all three units is $37.7 million, with a maximum annual payment limitation of $5.6 million. After the expiration of the PVNGS Unit 1 and 2 leases in January 2023 and January 2024, PNM’s maximum potential retrospective premium assessment per incident for all three units is $36.3 million, with a maximum annual payment limitation of $5.4 million, to be adjusted periodically for inflation.

The PVNGS participants maintain insurance for damage to, and decontamination of, property at PVNGS in the aggregate amount of $2.8 billion, a substantial portion of which must first be applied to stabilization and decontamination. These coverages are provided by Nuclear Electric Insurance Limited (“NEIL”). The primary policy offered by NEIL contains a sublimit of $2.25 billion for non-nuclear property damage. If NEIL’s losses in any policy year exceed accumulated funds, PNM is subject to retrospective premium adjustments of $4.9 million. The insurance coverages discussed in this and the previous paragraph are subject to certain policy conditions, sublimits, and exclusions.