c. Environmental - MGE Energy and MGE.

Water Quality

Water quality regulations promulgated by the EPA and WDNR in accordance with the Federal Water Pollution Control Act, or more commonly known as the Clean Water Act (CWA), impose restrictions on discharges of various pollutants into surface waters. The CWA also regulates surface water quality issues that affect aquatic life, such as water temperatures, intake structures, and wetlands filling. The CWA also includes discharge standards, which require the use of effluent-treatment processes equivalent to categorical "best practicable" or "best available" technologies. The CWA regulates discharges from "point sources," such as power plants, through establishing discharge limits in water discharge permits. MGE's power plants operate under Wisconsin Pollution Discharge Elimination System (WPDES) permits issued by the WDNR to ensure compliance with these discharge limits. Permits are subject to periodic renewal.

EPA's Effluent Limitations Guidelines and Standards for Steam Electric Power Generating Point Source Category

In November 2015, the EPA published its final rule setting Effluent Limitations Guidelines (ELG) for the steam electric power generating industry. The ELG rule establishes federal limits on the amount of metals and other pollutants that can be discharged in wastewater from new and existing steam electric generation plants. The rule will be applied to Wisconsin-based power plants as they renew their WPDES permits, no later than 2023. The operators of the Columbia and Elm Road Units have indicated that equipment upgrades may be necessary to comply with the new discharge standards. Management believes that any compliance costs will be recovered in future rates based on previous treatment of environmental compliance projects.

EPA Cooling Water Intake Rules (Section 316(b))

Section 316(b) of the Clean Water Act requires that the cooling water intake structures at electric power plants meet best available technology standards so that mortality from entrainment (drawing aquatic life into a plant's cooling system) and impingement (trapping aquatic life on screens) are reduced. The EPA finalized its Section 316(b) rule for existing facilities in 2014. Section 316(b) requirements are implemented in Wisconsin through modifications to plants' WPDES permits, which govern plant wastewater discharges.

The WCCF, Blount, and Columbia plants are considered existing plants under this rule. The WCCF facility already employs a system that meets the Section 316(b) rule. The Blount plant's WPDES permit assumes that Blount meets best technology available (BTA) for the duration of the permit, which expires in 2023. However, MGE needs to perform an entrainment study by the end of 2021 to determine future BTA, which will be included with the next permit renewal. Section 316(b) applies to river intakes at the Columbia plant. The operator of the Columbia plant is in the process of a WPDES permit renewal. The draft permit directs the Columbia operator to conduct similar studies on their intake structures. The study requirements will not be known until the permit is final. Future BTA requirements at Blount and Columbia will be based on the results of these required intake studies and will be specified in the next permits issued in 2023 or later. MGE expects that the Section 316(b) rule will not have a material effect on its existing plants.

Energy Efficiency and Renewables

The Wisconsin Energy Efficiency and Renewables Act requires that 10% of the state's electricity be generated from renewable sources. MGE is in compliance with the requirement. The costs to comply with the Act and its accompanying regulations are being recovered in rates.

Air Quality

Federal and state air quality regulations impose restrictions on various emissions, including emissions of particulate matter (PM), sulfur dioxide (SO₂), nitrogen oxides (NO_x), and other pollutants, and require permits for operation of emission sources. These permits have been obtained by MGE and must be renewed periodically. Current EPA initiatives under the Clean Air Act, including the Cross-State Air Pollution Rule (CSAPR), and National Ambient Air Quality Standards (NAAQS), and the Affordable Clean Energy (ACE) rule have the potential to result in additional operating and capital expenditure costs for MGE.

EPA's Greenhouse Gas (GHG) Reduction Guidelines under the Clean Air Act 111(d) Rule

The EPA's Clean Power Plan (CPP) rule became effective in December 2015, setting guidelines for states to use in developing plans to control GHG emissions from existing fossil fuel-fired EGUs and systems. When fully implemented in 2030, the CPP was projected to reduce GHG emissions from this sector by 32% below 2005 levels. States were given up to three years to submit a plan or be subject to a federal plan to meet the reduction goals, and states were expected to meet interim goals starting in 2022 and the final goals in 2030. Implementation of the rule was expected to have a direct impact on coal and natural gas fired generating units, including possible changes in dispatch and additional operating costs. In February 2016, the U.S. Supreme Court stayed implementation of the CPP which remains in effect. In October 2017, the EPA proposed to rescind the CPP.

In August2018, the EPA proposed the ACE rule which would replace the CPP, if successfully implemented. The ACE proposal directs states to submit plans to the EPA for approval that implement standards of performance (called Best System of Emissions Reductions, or BSER) for individual EGUs over 25 MW. ACE defines BSER as on-site, heat-rate efficiency improvements, whereas the CPP defines BSERs using carbon dioxide emission performance rates. Simple cycle units such as smaller combustion units, and combined cycle units such as the WCCF are exempt from the proposed rule. Under the ACE proposal, if a state fails to prepare a plan, or its plan is not approved by the EPA, a federal implementation plan will be issued for that state. The proposed ACE as it is currently written has the potential to impact Blount, Columbia, and the Elm Road Units.

Given the pending legal proceedings, and the proposed ACE rule, the nature and timing of any final requirements is subject to uncertainty. MGE is unable to determine with any certainty the impact of the CPP and proposed ACE rule on our operations. If an ACE rule is implemented substantially in the form of the CPP rule, it is expected to have a material impact on MGE. MGE will continue to monitor developments with the proposed ACE rule, the CPP rule, and related litigation.

National Ambient Air Quality Standards (NAAQS) and Related Rules

The EPA's NAAQS regulations have been developed to set ambient levels of six pollutants to protect sensitive human populations (primary NAAQS) and the environment (secondary NAAQS) from the negative effects of exposure to these pollutants at higher levels. The Clean Air Act requires that the EPA periodically review, and adjust as necessary, the NAAQS for these six air pollutants. The EPA's NAAQS review can result in a lowering of the allowed ambient levels of a pollutant, a change in how the pollutant is monitored, and/or a change in which sources of that pollutant are regulated. States implement any necessary monitoring and measurement changes and recommend areas for attainment (meets the ambient requirements) or nonattainment (does not meet these standards). The EPA makes the final attainment and nonattainment determinations. States must come up with a state implementation plan (SIP) to get nonattainment areas into attainment and maintain air quality in attainment areas. A company with facilities located in a nonattainment area will be most affected. Their facilities may be subject to additional data submissions and measurement during permitting renewals, their facilities may need to meet new emission limitations set by the SIP (which could result in significant capital expenditures), and the company may have additional expenses and/or difficulties expanding existing facilities or building new facilities. The process from determining acceptable primary and/or secondary NAAQS to executing SIPs can take years. Since the NAAQS regulations have the potential to affect both existing and new facilities in areas, MGE continuously monitors changes to these rules to evaluate whether changes could impact its operations. In addition, the EPA has adopted interstate transport rules, such as the CSAPR, to address contributions to NAAQS nonattainment from upwind sources in neighboring states. In the following paragraphs we discuss specific NAAQS and transport rule developments that may affect MGE.

Ozone NAAQS

In May 2018, the EPA issued a final rule which designated the northeast portion of Milwaukee County as being in nonattainment with Ozone NAAQS. The Elm Road Units are located in Milwaukee County, outside the designated nonattainment area. In August 2018, several environmental groups, the City of Chicago, and the State of Illinois filed federal lawsuits challenging several of the EPA's attainment designation decisions, including the partial Milwaukee County designation as being too narrow and not sufficiently protective. MGE is monitoring the outcome of this lawsuit and how it may affect the Elm Road Units in Milwaukee County. If the entire county where to be considered in nonattainment as a result of this lawsuit, the State of Wisconsin would need to develop an implementation plan that addressed emissions that contribute to Ozone (NO_x and Volatile Organic Compound emissions) for the County, which could affect operations and emissions control obligations of the Elm Road units. MGE is monitoring the outcome of this lawsuit and how it may affect the Elm Road Units in Milwaukee County. At this time MGE expects that the 2015 Ozone NAAQS will not have a material effect on its existing plants based on final designations.

EPA's Cross-State Air Pollution Rule: Proposed Ozone Season Update based on 2008 Ozone NAAQS

The EPA's CSAPR is an interstate air pollution transport rule designed to reduce ozone and fine particulate (PM2.5) air levels in areas that the EPA has determined are being significantly impacted by pollution from neighboring and upwind states. This is accomplished in the CSAPR through a reduction in SO₂ and NO_x from qualifying fossil-fuel fired power plants in upwind or "contributing" states. NO_x and SO₂ contribute to fine particulate pollution and NO_x contributes to ozone formation in downwind areas. Reductions are achieved through a cap and trade system. Individual plants can meet their caps through modifications and/or buying allowances on the market.

In October 2016, the EPA finalized rulemaking for an update to CSAPR that incorporated 2008 Ozone NAAQS standards into the rule (the original CSAPR is based on 1997 Ozone NAAQS standards) and began further reducing summertime ozone season NO_x allowances in 2017. The update affects 22 states, including Wisconsin, by further limiting statewide NO_x allowances in each of those states. The rule also includes revisions to CSAPR that are designed to address issues remaining from the D.C. Circuit remand of CSAPR, including Wisconsin's inclusion in the NO_x ozone season portion of the rule. The State of Wisconsin filed a legal challenge to the CSAPR update rule asserting, among other things, that the rule over-controls NO_x emissions in Wisconsin.

MGE has met our CSAPR obligations in 2018 and 2017 through a combination of reduced emissions through pollution control (e.g. SCR installation at Columbia), as well as owned, received, and purchased allowances. There remains uncertainty around CSAPR due to legal challenges, however, MGE expects that we will meet ongoing CSAPR obligations for the foreseeable future. MGE will continue to monitor developments and litigations to this rule.

Clean Air Visibility Rule (CAVR)

Columbia is subject to the best available retrofit technology (BART) regulations, a subsection of the EPA's CAVR, which may require pollution control retrofits. Columbia's existing pollution control upgrades, and the EPA's stance that compliance with the CSAPR equals compliance with BART, should mean that Columbia will not need to do additional work to meet BART requirements. At this time, however, the BART regulatory obligations, compliance strategies, and costs remain uncertain in Wisconsin due to the continued legal challenges surrounding CSAPR and CAVR. MGE will continue to monitor developments to this rule.

Solid Waste

EPA's Coal Combustion Residuals Rule

The EPA's Coal Combustion Residuals Rule (CCR), which regulates coal ash from burning coal for purpose of generating electricity as a solid waste, and defines what ash use activities would be considered generally exempt beneficial reuse of coal ash. The CCR rule also regulates existing, modified, and new landfills, ash ponds, and other surface impoundments used for coal combustion residuals by regulating their design, location, monitoring, and operation.

Review of the Elm Road Units has indicated that the costs to comply with this rule are not expected to be significant. Columbia's operator has completed a review of their system and has determined that an onsite ash pond will need to be closed and replaced with a dry ash handling system. The dry ash handling system installation is planned for 2020-2021.

In July 2018, the EPA published a final rule that included amendments to the CCR (which include the allowance of alternative performance standards for landfills and surface impoundments, revised risk-based groundwater protection standards, and an extension of the deadline by which certain facilities must cease the placement of waste in CCR units). In August 2018, the Court of Appeals for the D.C. Circuit vacated parts of the CCR for not being sufficiently protective of the environment. It is unclear how the EPA will respond to that decision. MGE will continue to monitor potential rule modifications to assess potential impacts on our operations.

In 2015, MGE recorded an asset retirement obligation for its share of the legal liability associated with the effect of the CCR. Actual costs of compliance may be different than the amount recorded due to potential changes in compliance strategies that will be used, as well as other potential cost estimate changes.

Columbia

Based upon current available information, compliance with various environmental requirements and initiatives is expected to result in significant additional operating and capital expenditures at Columbia as noted below.

Columbia Clean Air Act Litigation

Columbia is a coal-fired generating station operated by WPL in which WPL, WPSC, and MGE have ownership interests. In December 2009, the EPA sent a Notice of Violation (NOV) to the co-owners, including MGE. The NOV alleged that WPL, which is the plant operator, and the Columbia co-owners failed to comply with appropriate pre-construction review and permitting requirements and, as a result, violated the Prevention of Significant Deterioration program requirements, Title V Operating Permit requirements of the CAA, and the Wisconsin SIP. In June 2013, the court approved and entered a consent decree entered by the EPA, Sierra Club, and the co-owners of Columbia. One of the requirements of the consent decree requires installation of an SCR system at Columbia Unit 2 by December 31, 2018. Installation of the SCR was approved by the PSCW, which was placed in service in 2018.