Commitments and Contingencies	9 Months Ended
Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	12. COMMITMENTS AND CONTINGENCIES Contractual Commitments For information regarding long-term contractual commitments, including fuel and purchased power commitments, see Note 14 of the Westar Energy 2017 Form 10-K and Note 15 of the Great Plains Energy and KCP&L combined 2017 Form 10-K. Environmental Matters Set forth below are descriptions of contingencies related to environmental matters that may impact the Evergy Companies or their financial results. Management's assessment of these contingencies, which are based on federal and state statutes and regulations, and regulatory agency and judicial interpretations and actions, has evolved over time. There are a variety of final and proposed laws and regulations that could have a material adverse effect on the Evergy Companies operations and consolidated financial results. Due in part to the complex nature of environmental laws and regulations, the Evergy Companies are unable to assess the impact of potential changes that may develop with respect to the environmental contingencies described below. Cross-State Air Pollution Update Rule In September 2016, the Environmental Protection Agency (EPA) finalized the Cross-State Air Pollution Update Rule. The final rule addresses interstate transport of nitrogen oxides emissions in 22 states including Kansas, Missouri and Oklahoma during the ozone season and the impact from the formation of ozone on downwind states with respect to the 2008 ozone National Ambient Air Quality Standards (NAAQS). Starting with the 2017 ozone season, the final rule revised the existing ozone season allowance budgets for Missouri and Oklahoma and established an ozone season budget for Kansas. In June 2018, the EPA proposed that the Cross-State Air Pollution Update Rule satisfied the "Good Neighbor" obligations for the 2008 ozone NAAQS and therefore the EPA is proposing no additional reduction in the current ozone season allowance budgets. Various states and others are challenging the Cross-State Air Pollution Update Rule in the U.S. Court of Appeals for the D.C. Circuit (D.C. Circuit) but the rule remains in effect. It is not expected that this rule will have a material impact on the Evergy Companies' operations and consolidated financial results. National Ambient Air Quality Standards Under the Clean Air Act Amendments of 1990 (Clean Air Act), the EPA sets NAAQS for certain emissions known as the “criteria pollutants” considered harmful to public health and the environment, including two classes of particulate matter (PM), ozone, nitrogen dioxide (NO₂) (a precursor to ozone), carbon monoxide and sulfur dioxide (SO₂), which result from fossil fuel combustion. Areas meeting the NAAQS are designated attainment areas while those that do not meet the NAAQS are considered nonattainment areas. Each state must develop a plan to bring nonattainment areas into compliance with the NAAQS. NAAQS must be reviewed by the EPA at five-year intervals. In October 2015, the EPA strengthened the ozone NAAQS by lowering the standards from 75 ppb to 70 ppb. In September 2016, the Kansas Department of Health & Environment (KDHE) recommended to the EPA that they designate eight counties in the state of Kansas as in attainment with the standard, and each remaining county in Kansas as attainment/unclassifiable. Also, in September 2016, the Missouri Department of Natural Resources (MDNR) recommended to the EPA that they designate all Missouri counties in KCP&L's and GMO's service territories as attainment/unclassifiable. In November 2017, the EPA designated all counties in the State of Kansas as well as the Missouri counties in KCP&L's and GMO's service territories as attainment/unclassifiable. It is not expected that this will have a material impact on the Evergy Companies' consolidated financial results. In December 2012, the EPA strengthened an existing NAAQS for one class of PM. In December 2014, the EPA designated the entire state of Kansas and those portions of Missouri served by KCP&L and GMO as attainment/unclassifiable with the standard. It is not expected that this will have a material impact on the Evergy Companies' operations or consolidated financial results. The Evergy Companies continue to communicate with their regulatory agencies regarding these standards and evaluate what impact the revised NAAQS could have on their operations and consolidated financial results. If areas surrounding the Evergy Companies' facilities are designated in the future as nonattainment and/or it is required to install additional equipment to control emissions at facilities of the Evergy Companies, it could have a material impact on the operations and consolidated financial results of the Evergy Companies. Greenhouse Gases Burning coal and other fossil fuels releases carbon dioxide (CO₂) and other gases referred to as greenhouse gases (GHG). Various regulations under the federal Clean Air Act limit CO₂ and other GHG emissions, and in addition, other measures are being imposed or offered by individual states, municipalities and regional agreements with the goal of reducing GHG emissions. In October 2015, the EPA published a rule establishing new source performance standards (NSPS) for GHGs that limit CO₂ emissions for new, modified and reconstructed coal and natural gas fueled electric generating units to various levels per MWh depending on various characteristics of the units. Legal challenges to the GHG NSPS have been filed in the D.C. Circuit by various states and industry members. Also in October 2015, the EPA published a rule establishing guidelines for states to regulate CO₂ emissions from existing power plants. The standards for existing plants are known as the Clean Power Plan (CPP). Under the CPP, interim emissions performance rates must be achieved beginning in 2022 and final emissions performance rates must be achieved by 2030. Legal challenges to the CPP were filed by groups of states and industry members, including Westar Energy, in the D.C. Circuit. The CPP was stayed by the Supreme Court in February 2016 and, accordingly, is not currently being implemented by the states. In April 2017, the EPA published in the Federal Register a notice of withdrawal of the proposed CPP federal plan, proposed model trading rules and proposed Clean Energy Incentive Program design details. Also in April 2017, the EPA published a notice in the Federal Register that it was initiating administrative reviews of the CPP and the GHG NSPS. In October 2017, the EPA issued a proposed rule to repeal the CPP. The proposed rule indicates the CPP exceeds EPA’s authority and the EPA has not determined whether they will issue a replacement rule. The EPA solicited comments on the legal interpretations contained in this rulemaking. In December 2017, the EPA issued an advance notice of proposed rulemaking to solicit feedback on specific areas of the CPP that could be changed. In August 2018, the EPA published in the Federal Register proposed regulations which contained (1) emission guidelines for GHG emissions from existing electric utility generating units (EGUs), (2) revisions to emission guideline implementing regulations and (3) revisions to the new source review (NSR) program. The proposed emission guidelines are better known as the Affordable Clean Energy (ACE) Rule. The ACE Rule would establish emission guidelines for states to use in the development of plans to reduce GHG emissions from existing coal-fired EGUs. The ACE Rule is also the replacement rule for the CPP. The ACE rule proposes to determine the “best system of emission reduction” for GHG emissions from existing coal-fired EGUs as on-site, heat-rate efficiency improvements. The proposed rule also provides states with a list of candidate technologies that can be used to establish standards of performance and incorporate these performance standards into state plans. In order for the states to be able to effectively implement the proposed emission guidelines contained in the ACE Rule, the EPA is proposing new regulations under 111(d) of the Clean Air Act to help clarify this process. In addition, the EPA is proposing revisions to the NSR program that will reduce the likelihood of triggering NSR for proposed heat-rate efficiency improvement projects at existing coal-fired EGUs. The EPA accepted comments on these three proposed regulatory changes until October 31, 2018. Due to the future uncertainty of the CPP and ACE rules, the Evergy Companies cannot determine the impact on their operations or consolidated financial results, but the cost to comply with the CPP, should it be upheld and implemented in its current or a substantially similar form, or ACE in its current or a substantially similar form, could be material. Water The Evergy Companies discharge some of the water used in generation and other operations. This water may contain substances deemed to be pollutants. Revised rules governing such discharges from coal-fired power plants were issued in November 2015. The final rule establishes effluent limitations guidelines (ELG) and standards for wastewater discharges, including limits on the amount of toxic metals and other pollutants that can be discharged. Implementation timelines for these requirements vary from 2018 to 2023. In April 2017, the EPA announced it is reconsidering the ELG rule and court challenges have been placed in abeyance pending the EPA's review. In September 2017, the EPA finalized a rule to postpone the compliance dates for the new, more stringent, effluent limitations and pretreatment standards for bottom ash transport water and flue gas desulfurization wastewater. These compliance dates have been postponed for two years while the EPA completes its administrative reconsideration of the ELG rule. The Evergy Companies are evaluating the final rule and related developments and cannot predict the resulting impact on their operations or consolidated financial results, but believe costs to comply could be material if the rule is implemented in its current or substantially similar form. In October 2014, the EPA's final standards for cooling intake structures at power plants to protect aquatic life took effect. The standards, based on Section 316(b) of the federal Clean Water Act (CWA), require subject facilities to choose among seven best available technology options to reduce fish impingement. In addition, some facilities must conduct studies to assist permitting authorities to determine whether and what site-specific controls, if any, would be required to reduce entrainment of aquatic organisms. The Evergy Companies' current analysis indicates this rule will not have a significant impact on their coal plants that employ cooling towers or cooling lakes that can be classified as closed cycle cooling and do not expect the impact from this rule to be material. Plants without closed cycle cooling are under evaluation for compliance with these standards and may require additional controls that could be material. KCP&L holds a permit from MDNR covering water discharge from its Hawthorn Station. The permit authorizes KCP&L to, among other things, withdraw water from the Missouri River for cooling purposes and return the heated water to the Missouri River. KCP&L has applied for a renewal of this permit and the EPA has submitted an interim objection letter regarding the allowable amount of heat that can be contained in the returned water. Until this matter is resolved, KCP&L continues to operate under its current permit. Evergy and KCP&L cannot predict the outcome of this matter; however, while less significant outcomes are possible, this matter may require a reduction in generation, installation of cooling towers or other technology to cool the water, or both, any of which could have a material impact on Evergy's and KCP&L's operations and consolidated financial results. In June 2015, the EPA along with the U.S. Army Corps of Engineers issued a final rule, effective August 2015, defining the Waters of the United States (WOTUS) for purposes of the CWA. This rulemaking has the potential to impact all programs under the CWA. Expansion of regulated waterways is possible under the rule depending on regulating authority interpretation, which could impact several permitting programs. Various states and others have filed lawsuits challenging the WOTUS rule. In February 2018, the EPA and the U.S. Army Corps of Engineers finalized a rule adding an applicability date to the 2015 rule, which makes the implementation date of the rule February 2020. In July 2017, the EPA and the U.S. Army Corps of Engineers published in the Federal Register a proposed rule that would, if implemented, reinstate the definition of WOTUS that existed prior to the June 2015 expansion of the definition. Final action on the proposed rule is expected in 2018 as it is currently at the Office of Management and Budget for inter-agency review. The Evergy Companies are currently evaluating the WOTUS rule and related developments but do not believe the rule, if upheld and implemented in its current or substantially similar form, will have a material impact on the Evergy Companies' operations or consolidated financial results. Regulation of Coal Combustion Residuals In the course of operating their coal generation plants, the Evergy Companies produce CCRs, including fly ash, gypsum and bottom ash. Some of this ash production is recycled, principally by selling to the aggregate industry. The EPA published a rule to regulate CCRs in April 2015, which will require additional CCR handling, processing and storage equipment and closure of certain ash disposal units. The Water Infrastructure Improvements for the Nation (WIIN) Act allows states to achieve delegated authority for CCR rules from the EPA. This has the potential to impact compliance options. In July 2018, the KDHE submitted a CCR permit program application to the EPA under authority of the WIIN Act. Final action on the application by the EPA is expected to occur within one year from the application date. MDNR is working on a rule revision which will allow the state to apply for authority over the federal CCR regulation. The application is expected to be submitted to the EPA in early 2019. Similar to the process in Kansas, this would allow Missouri state regulators to gain control of the CCR program. It will take up to one year from submittal of the Missouri application for EPA to take final action and grant authority to the state. On July 30, 2018, the EPA published in the Federal Register a final rule called the Phase I CCR Remand Rule in order to modify portions of the 2015 rulemaking. The Phase I rule provides a timeline extension for unlined impoundments and landfills that must close due to groundwater impacts or location restrictions. The rule also sets risk-based limits for certain groundwater constituents where a maximum contaminant level did not previously exist. These rule modifications add flexibility when assessing compliance. On August 21, 2018, the D.C. Circuit court issued a ruling in the CCR rule litigation between the Utility Solid Waste Activities Group, the EPA and environmental organizations. Portions of the rule were vacated and were remanded back to EPA for potential modification. Potential revisions to remanded sections could force all unlined surface impoundments to close regardless of groundwater conditions. Any changes to the rule based on this court decision will require additional rulemaking from the EPA. The Evergy Companies have recorded AROs for their current estimates for the closure of ash disposal ponds but the revision of these AROs may be required in the future due to changes in existing CCR regulations, changes in interpretation of existing CCR regulations, the results of groundwater monitoring of CCR units, or changes in the timing or cost to close ash disposal ponds. If revisions to these AROs are necessary, the impact on the Evergy Companies' operations or consolidated financial results could be material. Storage of Spent Nuclear Fuel Under the Nuclear Waste Policy Act of 1982, the Department of Energy (DOE) is responsible for the permanent disposal of spent nuclear fuel. In 2010, the DOE filed a motion with the Nuclear Regulatory Commission (NRC) to withdraw its then pending application to construct a national repository for the disposal of spent nuclear fuel and high-level radioactive waste at Yucca Mountain, Nevada. An NRC board denied the DOE's motion to withdraw its application and the DOE appealed that decision to the full NRC. In 2011, the NRC issued an evenly split decision on the appeal and also ordered the licensing board to close out its work on the DOE's application by the end of 2011 due to a lack of funding. These agency actions prompted the states of Washington and South Carolina, and a county in South Carolina, to file a lawsuit in a federal Court of Appeals asking the court to compel the NRC to resume its license review and to issue a decision on the license application. In August 2013, the court ordered the NRC to resume its review of the DOE's application. The NRC has not yet issued its decision. Wolf Creek has elected to build a dry cask storage facility to expand its existing on-site spent nuclear fuel storage, which is expected to provide additional capacity prior to 2025. Wolf Creek has finalized a settlement agreement through 2019 with the DOE for reimbursement of costs to construct this facility that would not have otherwise been incurred had the DOE begun accepting spent nuclear fuel. The Evergy Companies expect the majority of the remaining cost to construct the dry cask storage facility that would not have otherwise been incurred will be reimbursed by the DOE. The Evergy Companies cannot predict when, or if, an off-site storage site or alternative disposal site will be available to receive Wolf Creek's spent nuclear fuel and will continue to monitor this activity.

12. COMMITMENTS AND CONTINGENCIES

Contractual Commitments

For information regarding long-term contractual commitments, including fuel and purchased power commitments, see Note 14 of the Westar Energy 2017 Form 10-K and Note 15 of the Great Plains Energy and KCP&L combined 2017 Form 10-K.

Environmental Matters

Set forth below are descriptions of contingencies related to environmental matters that may impact the Evergy Companies or their financial results. Management's assessment of these contingencies, which are based on federal and state statutes and regulations, and regulatory agency and judicial interpretations and actions, has evolved over time. There are a variety of final and proposed laws and regulations that could have a material adverse effect on the Evergy Companies operations and consolidated financial results. Due in part to the complex nature of environmental laws and regulations, the Evergy Companies are unable to assess the impact of potential changes that may develop with respect to the environmental contingencies described below.

Cross-State Air Pollution Update Rule

In September 2016, the Environmental Protection Agency (EPA) finalized the Cross-State Air Pollution Update Rule. The final rule addresses interstate transport of nitrogen oxides emissions in 22 states including Kansas, Missouri and Oklahoma during the ozone season and the impact from the formation of ozone on downwind states with respect to the 2008 ozone National Ambient Air Quality Standards (NAAQS). Starting with the 2017 ozone season, the final rule revised the existing ozone season allowance budgets for Missouri and Oklahoma and established an ozone season budget for Kansas. In June 2018, the EPA proposed that the Cross-State Air Pollution Update Rule satisfied the "Good Neighbor" obligations for the 2008 ozone NAAQS and therefore the EPA is proposing no additional reduction in the current ozone season allowance budgets. Various states and others are challenging the Cross-State Air Pollution Update Rule in the U.S. Court of Appeals for the D.C. Circuit (D.C. Circuit) but the rule remains in effect. It is not expected that this rule will have a material impact on the Evergy Companies' operations and consolidated financial results.

National Ambient Air Quality Standards

Under the Clean Air Act Amendments of 1990 (Clean Air Act), the EPA sets NAAQS for certain emissions known as the “criteria pollutants” considered harmful to public health and the environment, including two classes of particulate matter (PM), ozone, nitrogen dioxide (NO₂) (a precursor to ozone), carbon monoxide and sulfur dioxide (SO₂), which result from fossil fuel combustion. Areas meeting the NAAQS are designated attainment areas while those that do not meet the NAAQS are considered nonattainment areas. Each state must develop a plan to bring nonattainment areas into compliance with the NAAQS. NAAQS must be reviewed by the EPA at five-year intervals.

In October 2015, the EPA strengthened the ozone NAAQS by lowering the standards from 75 ppb to 70 ppb. In September 2016, the Kansas Department of Health & Environment (KDHE) recommended to the EPA that they designate eight counties in the state of Kansas as in attainment with the standard, and each remaining county in Kansas as attainment/unclassifiable. Also, in September 2016, the Missouri Department of Natural Resources (MDNR) recommended to the EPA that they designate all Missouri counties in KCP&L's and GMO's service territories as attainment/unclassifiable. In November 2017, the EPA designated all counties in the State of Kansas as well as the Missouri counties in KCP&L's and GMO's service territories as attainment/unclassifiable. It is not expected that this will have a material impact on the Evergy Companies' consolidated financial results.

In December 2012, the EPA strengthened an existing NAAQS for one class of PM. In December 2014, the EPA designated the entire state of Kansas and those portions of Missouri served by KCP&L and GMO as attainment/unclassifiable with the standard. It is not expected that this will have a material impact on the Evergy Companies' operations or consolidated financial results.

The Evergy Companies continue to communicate with their regulatory agencies regarding these standards and evaluate what impact the revised NAAQS could have on their operations and consolidated financial results. If areas surrounding the Evergy Companies' facilities are designated in the future as nonattainment and/or it is required to install additional equipment to control emissions at facilities of the Evergy Companies, it could have a material impact on the operations and consolidated financial results of the Evergy Companies.

Greenhouse Gases

Burning coal and other fossil fuels releases carbon dioxide (CO₂) and other gases referred to as greenhouse gases (GHG). Various regulations under the federal Clean Air Act limit CO₂ and other GHG emissions, and in addition, other measures are being imposed or offered by individual states, municipalities and regional agreements with the goal of reducing GHG emissions.

In October 2015, the EPA published a rule establishing new source performance standards (NSPS) for GHGs that limit CO₂ emissions for new, modified and reconstructed coal and natural gas fueled electric generating units to various levels per MWh depending on various characteristics of the units. Legal challenges to the GHG NSPS have been filed in the D.C. Circuit by various states and industry members. Also in October 2015, the EPA published a rule establishing guidelines for states to regulate CO₂ emissions from existing power plants. The standards for existing plants are known as the Clean Power Plan (CPP). Under the CPP, interim emissions performance rates must be achieved beginning in 2022 and final emissions performance rates must be achieved by 2030. Legal challenges to the CPP were filed by groups of states and industry members, including Westar Energy, in the D.C. Circuit. The CPP was stayed by the Supreme Court in February 2016 and, accordingly, is not currently being implemented by the states.

In April 2017, the EPA published in the Federal Register a notice of withdrawal of the proposed CPP federal plan, proposed model trading rules and proposed Clean Energy Incentive Program design details. Also in April 2017, the EPA published a notice in the Federal Register that it was initiating administrative reviews of the CPP and the GHG NSPS.

In October 2017, the EPA issued a proposed rule to repeal the CPP. The proposed rule indicates the CPP exceeds EPA’s authority and the EPA has not determined whether they will issue a replacement rule. The EPA solicited comments on the legal interpretations contained in this rulemaking.

In December 2017, the EPA issued an advance notice of proposed rulemaking to solicit feedback on specific areas of the CPP that could be changed.

In August 2018, the EPA published in the Federal Register proposed regulations which contained (1) emission guidelines for GHG emissions from existing electric utility generating units (EGUs), (2) revisions to emission guideline implementing regulations and (3) revisions to the new source review (NSR) program. The proposed emission guidelines are better known as the Affordable Clean Energy (ACE) Rule. The ACE Rule would establish emission guidelines for states to use in the development of plans to reduce GHG emissions from existing coal-fired EGUs. The ACE Rule is also the replacement rule for the CPP. The ACE rule proposes to determine the “best system of emission reduction” for GHG emissions from existing coal-fired EGUs as on-site, heat-rate efficiency improvements. The proposed rule also provides states with a list of candidate technologies that can be used to establish standards of performance and incorporate these performance standards into state plans. In order for the states to be able to effectively implement the proposed emission guidelines contained in the ACE Rule, the EPA is proposing new regulations under 111(d) of the Clean Air Act to help clarify this process. In addition, the EPA is proposing revisions to the NSR program that will reduce the likelihood of triggering NSR for proposed heat-rate efficiency improvement projects at existing coal-fired EGUs. The EPA accepted comments on these three proposed regulatory changes until October 31, 2018.

Due to the future uncertainty of the CPP and ACE rules, the Evergy Companies cannot determine the impact on their operations or consolidated financial results, but the cost to comply with the CPP, should it be upheld and implemented in its current or a substantially similar form, or ACE in its current or a substantially similar form, could be material.

Water

The Evergy Companies discharge some of the water used in generation and other operations. This water may contain substances deemed to be pollutants. Revised rules governing such discharges from coal-fired power plants were issued in November 2015. The final rule establishes effluent limitations guidelines (ELG) and standards for wastewater discharges, including limits on the amount of toxic metals and other pollutants that can be discharged. Implementation timelines for these requirements vary from 2018 to 2023. In April 2017, the EPA announced it is reconsidering the ELG rule and court challenges have been placed in abeyance pending the EPA's review. In September 2017, the EPA finalized a rule to postpone the compliance dates for the new, more stringent, effluent limitations and pretreatment standards for bottom ash transport water and flue gas desulfurization wastewater. These compliance dates have been postponed for two years while the EPA completes its administrative reconsideration of the ELG rule. The Evergy Companies are evaluating the final rule and related developments and cannot predict the resulting impact on their operations or consolidated financial results, but believe costs to comply could be material if the rule is implemented in its current or substantially similar form.

In October 2014, the EPA's final standards for cooling intake structures at power plants to protect aquatic life took effect. The standards, based on Section 316(b) of the federal Clean Water Act (CWA), require subject facilities to choose among seven best available technology options to reduce fish impingement. In addition, some facilities must conduct studies to assist permitting authorities to determine whether and what site-specific controls, if any, would be required to reduce entrainment of aquatic organisms. The Evergy Companies' current analysis indicates this rule will not have a significant impact on their coal plants that employ cooling towers or cooling lakes that can be classified as closed cycle cooling and do not expect the impact from this rule to be material. Plants without closed cycle cooling are under evaluation for compliance with these standards and may require additional controls that could be material.

KCP&L holds a permit from MDNR covering water discharge from its Hawthorn Station. The permit authorizes KCP&L to, among other things, withdraw water from the Missouri River for cooling purposes and return the heated water to the Missouri River. KCP&L has applied for a renewal of this permit and the EPA has submitted an interim objection letter regarding the allowable amount of heat that can be contained in the returned water. Until this matter is resolved, KCP&L continues to operate under its current permit. Evergy and KCP&L cannot predict the outcome of this matter; however, while less significant outcomes are possible, this matter may require a reduction in generation, installation of cooling towers or other technology to cool the water, or both, any of which could have a material impact on Evergy's and KCP&L's operations and consolidated financial results.

In June 2015, the EPA along with the U.S. Army Corps of Engineers issued a final rule, effective August 2015, defining the Waters of the United States (WOTUS) for purposes of the CWA. This rulemaking has the potential to impact all programs under the CWA. Expansion of regulated waterways is possible under the rule depending on regulating authority interpretation, which could impact several permitting programs. Various states and others have filed lawsuits challenging the WOTUS rule. In February 2018, the EPA and the U.S. Army Corps of Engineers finalized a rule adding an applicability date to the 2015 rule, which makes the implementation date of the rule February 2020. In July 2017, the EPA and the U.S. Army Corps of Engineers published in the Federal Register a proposed rule that would, if implemented, reinstate the definition of WOTUS that existed prior to the June 2015 expansion of the definition. Final action on the proposed rule is expected in 2018 as it is currently at the Office of Management and Budget for inter-agency review. The Evergy Companies are currently evaluating the WOTUS rule and related developments but do not believe the rule, if upheld and implemented in its current or substantially similar form, will have a material impact on the Evergy Companies' operations or consolidated financial results.

Regulation of Coal Combustion Residuals

In the course of operating their coal generation plants, the Evergy Companies produce CCRs, including fly ash, gypsum and bottom ash. Some of this ash production is recycled, principally by selling to the aggregate industry. The EPA published a rule to regulate CCRs in April 2015, which will require additional CCR handling, processing and storage equipment and closure of certain ash disposal units. The Water Infrastructure Improvements for the Nation (WIIN) Act allows states to achieve delegated authority for CCR rules from the EPA. This has the potential to impact compliance options. In July 2018, the KDHE submitted a CCR permit program application to the EPA under authority of the WIIN Act. Final action on the application by the EPA is expected to occur within one year from the application date. MDNR is working on a rule revision which will allow the state to apply for authority over the federal CCR regulation. The application is expected to be submitted to the EPA in early 2019. Similar to the process in Kansas, this would allow Missouri state regulators to gain control of the CCR program. It will take up to one year from submittal of the Missouri application for EPA to take final action and grant authority to the state.

On July 30, 2018, the EPA published in the Federal Register a final rule called the Phase I CCR Remand Rule in order to modify portions of the 2015 rulemaking. The Phase I rule provides a timeline extension for unlined impoundments and landfills that must close due to groundwater impacts or location restrictions. The rule also sets risk-based limits for certain groundwater constituents where a maximum contaminant level did not previously exist. These rule modifications add flexibility when assessing compliance.

On August 21, 2018, the D.C. Circuit court issued a ruling in the CCR rule litigation between the Utility Solid Waste Activities Group, the EPA and environmental organizations. Portions of the rule were vacated and were remanded back to EPA for potential modification. Potential revisions to remanded sections could force all unlined surface impoundments to close regardless of groundwater conditions. Any changes to the rule based on this court decision will require additional rulemaking from the EPA.

The Evergy Companies have recorded AROs for their current estimates for the closure of ash disposal ponds but the revision of these AROs may be required in the future due to changes in existing CCR regulations, changes in interpretation of existing CCR regulations, the results of groundwater monitoring of CCR units, or changes in the timing or cost to close ash disposal ponds. If revisions to these AROs are necessary, the impact on the Evergy Companies' operations or consolidated financial results could be material.

Storage of Spent Nuclear Fuel

Under the Nuclear Waste Policy Act of 1982, the Department of Energy (DOE) is responsible for the permanent disposal of spent nuclear fuel. In 2010, the DOE filed a motion with the Nuclear Regulatory Commission (NRC) to withdraw its then pending application to construct a national repository for the disposal of spent nuclear fuel and high-level radioactive waste at Yucca Mountain, Nevada. An NRC board denied the DOE's motion to withdraw its application and the DOE appealed that decision to the full NRC. In 2011, the NRC issued an evenly split decision on the appeal and also ordered the licensing board to close out its work on the DOE's application by the end of 2011 due to a lack of funding. These agency actions prompted the states of Washington and South Carolina, and a county in South Carolina, to file a lawsuit in a federal Court of Appeals asking the court to compel the NRC to resume its license review and to issue a decision on the license application. In August 2013, the court ordered the NRC to resume its review of the DOE's application. The NRC has not yet issued its decision.

Wolf Creek has elected to build a dry cask storage facility to expand its existing on-site spent nuclear fuel storage, which is expected to provide additional capacity prior to 2025. Wolf Creek has finalized a settlement agreement through 2019 with the DOE for reimbursement of costs to construct this facility that would not have otherwise been incurred had the DOE begun accepting spent nuclear fuel. The Evergy Companies expect the majority of the remaining cost to construct the dry cask storage facility that would not have otherwise been incurred will be reimbursed by the DOE. The Evergy Companies cannot predict when, or if, an off-site storage site or alternative disposal site will be available to receive Wolf Creek's spent nuclear fuel and will continue to monitor this activity.