References in this Annual Report on Form 10-K to "Eversource," the "Company," "we," "our," and "us" refer to Eversource Energy and its consolidated subsidiaries. CL&P, NSTAR Electric, and PSNH are each doing business as Eversource Energy.  

From time to time, we make statements concerning our expectations, beliefs, plans, objectives, goals, strategies, assumptions of future events, future financial performance or growth and other statements that are not historical facts.  These statements are "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995.  You can generally identify our forward-looking statements through the use of words or phrases such as "estimate," "expect," "anticipate," "intend," "plan," "project," "believe," "forecast," "should," "could," and other similar expressions.  Forward-looking statements are based on the current expectations, estimates, assumptions or projections of management and are not guarantees of future performance.  These expectations, estimates, assumptions or projections may vary materially from actual results. Accordingly, any such statements are qualified in their entirety by reference to, and are accompanied by, the following important factors that could cause our actual results to differ materially from those contained in our forward-looking statements, including, but not limited to:

Other risk factors are detailed in our reports filed with the SEC and updated as necessary, and we encourage you to consult such disclosures.

Eversource Energy, headquartered in Boston, Massachusetts and Hartford, Connecticut, is a public utility holding company subject to regulation by the FERC under the Public Utility Holding Company Act of 2005. We are engaged primarily in the energy delivery business through the following wholly-owned utility subsidiaries:

CL&P, NSTAR Electric and PSNH also serve New England customers through Eversource Energy's electric transmission business. Along with NSTAR Gas, EGMA and Yankee Gas, each is doing business as Eversource Energy in its respective service territory.

Eversource Energy, CL&P, NSTAR Electric and PSNH each report their financial results separately. We also include information in this report on a segment basis for Eversource Energy. Eversource Energy has four reportable segments: electric distribution, electric transmission, natural gas distribution and water distribution. These segments represent substantially all of Eversource Energy's total consolidated revenues. CL&P, NSTAR Electric and PSNH do not report separate business segments.

Eversource Energy's electric distribution segment consists of the distribution businesses of CL&P, NSTAR Electric and PSNH, which are engaged in the distribution of electricity to retail customers in Connecticut, Massachusetts and New Hampshire, respectively, and the solar power facilities of NSTAR Electric, and the generation facilities of PSNH before such facilities were sold in January and August 2018.Electric.

CL&P's distribution business consists primarily of the purchase, delivery and sale of electricity to its residential, commercial and industrial customers. As of December 31, 2018,2020, CL&P furnished retail franchise electric service to approximately 1.251.27 million customers in 149 cities and towns in Connecticut, covering an area of approximately 4,400 square miles. CL&P does not own any electric generation facilities.

CL&P is subject to regulation by the PURA, which, among other things, has jurisdiction over rates, certain dispositions of property and plant, mergers and consolidations, issuances of long-term securities, standards of service and construction and operation of facilities.  CL&P's present general rate structure consists of various rate and service classifications covering residential, commercial and industrial services.  CL&P's retail rates include a delivery service component, which includes distribution, transmission, conservation, renewable energy programs and other charges that are assessed on all customers.

Under Connecticut law, all of CL&P's customers are entitled to choose their energy suppliers, while CL&P remains their electric distribution company.  For those customers who do not choose a competitive energy supplier, under SS rates for customers with less than 500 kilowatts of demand (residential customers and small and medium commercial and industrial customers), and LRS rates for customers with 500 kilowatts or more of demand (larger commercial and industrial customers), CL&P purchases power under standard offer contracts and passes the cost of the purchased power to customers through a combined charge on customers' bills.

The rates established by the PURA for CL&P are comprised of the following:

As required by regulation, CL&P jointlyhas entered into long-term contracts for the purchase of (i) products from renewable energy facilities, which may include energy, renewable energy certificates, or capacity, (ii) capacity-related contracts with generation facilities, and (iii) contracts for peaking capacity.  Some of these contracts are subject to sharing agreements with UI, entered into the following contracts whereby CL&P is responsible for 80 percent and UI will sharefor 20 percent andof the net costs or benefits.  CL&P will share 80 percent&P's portion of the costs and benefits (CL&P's portion of these costs are either recovered from,contracts will be paid by, or refunded to, customers through the FMCC):CL&P's customers.

As noted above, CL&P does not own any generation assets and purchases energy supply to serve its SS and LRS loads from a variety of competitive sources through requests for proposals. During 2018,2020, CL&P supplied approximately 4551 percent of its customer load at SS or LRS rates while the other 5549 percent of its customer load had migrated to competitive energy suppliers.  In terms of the total number of CL&P customers, this equates to 2823 percent being on competitive supply, while 7277 percent remain with SS or LRS. Because this customer migration is only for energy supply service, it has no impact on CL&P's electric distribution business or its operating income.

CL&P periodically enters into full requirements contracts for SS loads for periods of up to one year. CL&P typically enters into full requirements contracts for LRS loads every three months. Currently, CL&P has full requirements contracts in place for 100 percent of its SS loads for the first half of 2019.2021. For the second half of 2019,2021, CL&P has 7040 percent of its SS load under full requirements contracts and intends to purchase an additional 3060 percent of full requirements. None of the SS load for 20202022 has been procured. CL&P has full requirements contracts in place for its LRS loads through June 2019March 2021 and intends to purchase 100 percent of full requirements for the remainder of 2019.2021.

NSTAR Electric's distribution business consists primarily of the purchase, delivery and sale of electricity to its residential, commercial and industrial customers. As of December 31, 2018,2020, NSTAR Electric furnished retail franchise electric service to approximately 1.471.45 million customers in Boston and 139 cities and towns in eastern and western Massachusetts, including Cape Cod, Martha's Vineyard and the greater Springfield metropolitan area, covering an aggregate area of approximately 3,200 square miles.

NSTAR Electric does not own any generating facilities that are used to supply customers, and purchases its energy requirements from competitive energy suppliers.

In December 2016, the DPU approved NSTAR Electric's application to develop 62 MW of new solar power facilities in addition to the 8 MW of existing solar power facilities. Currently, NSTAR Electric owns, 58operates and maintains a total of 70 MW of solar power facilities on twenty-two sites in Massachusetts that were completed from 2010 through 2018. We expect the remaining 4 MW of new facilities to be completed in 2019. Similar to NSTAR Electric’s current practice on the existing 58 MW of solar power facilities, we expect thatMassachusetts.  NSTAR Electric will sell energy from the newthese facilities into the ISO-NE market. We estimate our investment in these new facilities will be approximately $170 million.market, with proceeds credited to customers.

NSTAR Electric is subject to regulation by the DPU, which, among other things, has jurisdiction over rates, certain dispositions of property and plant, mergers and consolidations, issuances of long-term securities, acquisition of securities, standards of service and construction and operation of facilities.  The present general rate structure for NSTAR Electric consists of various rate and service classifications covering residential, commercial and industrial services.

Under Massachusetts law, all customers of NSTAR Electric are entitled to choose their energy suppliers, while NSTAR Electric remains their electric distribution company.  NSTAR Electric purchases power from competitive suppliers on behalf of, and passes the related cost through to, its customers who do not choose a competitive energy supplier (basic service). Electric distribution companies in Massachusetts are required to obtain and resell power to retail customers through basic service for those who choose not to buy energy from a competitive energy supplier.  Most of the residential customers of NSTAR Electric have continued to buy their power from NSTAR Electric at basic service rates.  Most commercial and industrial customers have switched to a competitive energy supplier.

The Cape Light Compact, an inter-governmental organization consisting of the 21 towns and two counties on Cape Cod and Martha's Vineyard, serves 200,000 customers through the delivery of energy efficiency programs, consumer advocacy, competitive electricity supply and green power options.  NSTAR Electric continues to provide electric service to these customers including the delivery of power, maintenance of infrastructure, capital investment, meter reading, billing, and customer service.

The rates established by the DPU for NSTAR Electric are comprised of the following:

As required by regulation, NSTAR Electric along with two other Massachusetts electric utilities,has signed long-term commitments tofor the purchase a combined estimated generating capacity of approximately 101 MW of wind and solar powerenergy from one wind farm in New York (28 MW), and nine solar projects in Connecticut, Maine, New Hampshire and Rhode Island (73 MW), over 20 years. One solar project began operating in January 2019, and the other eight solar projects are scheduled to begin operating in late 2019. In addition, the one wind farm in New York is scheduled to begin operating by year end 2020.renewable energy facilities.

During 2018,2020, NSTAR Electric supplied approximately 5542 percent of its residential customer load, 3329 percent of its small C&I customer load, and 86 percent of its large C&I customer load at basic service rates. The remainder of its customer load was distributed between municipal aggregation and competitive supply. Because customer migration is limited to energy supply service, it has no impact on the deliveryNSTAR Electric’s electric distribution business or operating income of NSTAR Electric.

PSNH's distribution business consists primarily of the purchase, delivery and sale of electricity to its residential, commercial and industrial customers. As of December 31, 2018,2020, PSNH furnished retail franchise electric service to approximately 519,000528,000 retail customers in 211 cities and towns in New Hampshire, covering an area of approximately 5,630 square miles.

On January 10, 2018, PSNH completed the sale of its thermal generation assets pursuant to a 2017 purchase and sale agreement. The thermal generation facilities included approximately 1,100 MW of coal, natural gas, biomass and oil-fired electricity generation facilities. On August 26, 2018, PSNH completed the sale of its hydroelectric generation assets pursuant to a separate 2017 purchase and sale agreement. For further information, see "Generation Divestiture" below. As of December 31, 2018,2020, PSNH does not own any electric generation facilities.

PSNH is subject to regulation by the NHPUC, which, among other things, has jurisdiction over rates, certain dispositions of property and plant, mergers and consolidations, issuances of securities, standards of service and construction and operation of facilities.

Under New Hampshire law, all of PSNH's customers are entitled to choose competitive energy suppliers. During 2018,2020, approximately 2421 percent of all of PSNH's customers (approximately 5653 percent of load) were taking service from competitive energy suppliers.

The rates established by the NHPUC for PSNH are comprised of the following:

The default energy service charge and SCRC rates change semi-annually and the transmission and SBC rates change annually. These rates are reconciled annually in accordance with the policies and procedures of the NHPUC, with any differences refunded to, or recovered from, customers.

On May 28, 2019, PSNH filed an application with the NHPUC for a permanent increase in base distribution rates of approximately $70 million, effective July 1, 2020, which included the temporary rate increase request. Temporary rates remained in effect with a reconciliation of permanent rates retroactive to July 1, 2019 once permanent rates were established in a settlement approved byset.

On January 10, 2018, PSNH completed the sale of its thermal generation assets pursuant to the Thermal Agreement. In accordance with the Thermal Agreement, theassets. The original purchase price of $175 million was adjusted to reflect working capital adjustments, closing date adjustments and proration of taxes and fees prior to closing, totaling $40.9 million. In the second quarter of 2018, the purchase price was further adjusted by $17.3 million relating to the valuation of certain allowances.closing. As a result of these adjustments, net proceeds from the sale of the thermal assets totaled $116.8 million.

From January 1, 2018 through March 31, 2018, approximately 24 percentPSNH does not own any generation assets and purchases energy supply from a variety of PSNH's defaultcompetitive suppliers for its energy service load was met through its own generation and approximately 18 percent was met through long-term power supply provided pursuant to orders of the NHPUC. The remaining 58 percent of PSNH's load was met by short-term (less than one year) purchases and spot purchases in the competitive New England wholesale power market. Included in the 58 percent are PSNH's obligations to purchase power from approximately two dozen IPPs, the output of which it either uses to serve its customer load or sells into the ISO-NE market. Beginning on April 1, 2018, 100 percent of PSNH’s default energy service load was met through purchases of energy requirements from competitive sourcescustomers through requests for proposals issued periodically, consistent with NHPUC regulations.

During 2018,2020, PSNH supplied approximately 4246 percent of its customer load at default energy service rates while the other 5854 percent of its customer load had migrated to competitive energy suppliers.  Because this customer migration is only for energy supply service, it has no impact on PSNH’s electric distribution business or its operating income.

Each of CL&P, NSTAR Electric and PSNH owns and maintains transmission facilities that are part of an interstate power transmission grid over which electricity is transmitted throughout New England.  Each of CL&P, NSTAR Electric and PSNH, and most other New England utilities, are parties to a series of agreements that provide for coordinated planning and operation of the region's transmission facilities and the rules by which they acquire transmission services.  Under these arrangements, ISO-NE, a non-profit corporation whose board of directors and staff are independent of all market participants, serves as the regional transmission organization of the New England transmission system.  

Wholesale transmission revenues are recovered through FERC-approved formula rates.  Annual transmission revenue requirements include recovery of transmission costs and include a return on equity applied to transmission rate base. Transmission revenues are collected from New England customers, including distribution customers of CL&P, NSTAR Electric and PSNH.  The transmission rates provide for an annual true-up of estimated to actual costs.  The financial impacts of differences between actual and estimated costs are deferred for future recovery from, or refundedrefund to, transmission customers.

Four separate complaints have beenwere filed at the FERC by combinations of New England state attorneys general, state regulatory commissions, consumer advocates, consumer groups, municipal parties and other parties (collectively the "Complainants"). In each of the first three complaints, filed on October 1, 2011, December 27, 2012, and July 31, 2014, respectively, the Complainants challenged the NETOs' base ROE of 11.14 percent that had been utilized since 2005 and sought an order to reduce it prospectively from the date of the final FERC order and for the separate 15-month complaint periods. In the fourth complaint, filed April 29, 2016, the Complainants challenged the NETOs' base ROE billed of 10.57 percent and the maximum ROE for transmission incentive ("incentive cap")(incentive cap) of 11.74 percent, asserting that these ROEs were unjust and unreasonable.

Transmission rate base under our FERC-approved tariff primarily consists of our investment in transmission net utility plant less accumulated deferred income taxes.

NSTAR Gas distributes natural gas to approximately 296,000303,000 customers in 51 communities in central and eastern Massachusetts covering 1,067 square miles, andmiles. EGMA distributes natural gas to approximately 332,000 customers in 65 communities throughout Massachusetts covering 1,206 square miles. Yankee Gas distributes natural gas to approximately 237,000246,000 customers in 7274 cities and towns in Connecticut covering 2,1872,632 square miles. Total throughput (sales and transportation) in 20182020 was approximately 70.166.9 Bcf for NSTAR Gas, 54.9 Bcf for EGMA, and 58.654.6 Bcf for Yankee Gas. Our natural gas businesses provide firm natural gas sales and transportation service to eligible retail customers who require a continuous natural gas supply throughout the year, such as residential customers who rely on natural gas for heating, hot water and cooking needs, as well as commercial and industrial customers that rely on natural gas for space heating, hot water, cooking and commercial and industrial applications.

NSTAR Gas and Yankee GasEGMA are subject to regulation by the DPU and theYankee Gas is subject to regulation by PURA, respectively, which, among other things, have jurisdiction over rates, certain dispositions of property and plant, mergers and consolidations, issuances of long-term securities, standards of service and construction and operation of facilities.

Retail natural gas delivery and supply rates are established by the DPU and the PURA and are comprised of:

NSTAR Gas purchases financial contracts based on the New York Mercantile Exchange ("NYMEX")(NYMEX) natural gas futures in order to reduce cash flow variability associated with the price for approximately one-third of its normal winter season natural gas supplies.  These purchases are made under a program approved by the DPU in 2006.  This practice attempts to minimize the impact of fluctuations in natural gas prices to NSTAR Gas' firm natural gas customers.  These financial contracts do not procure natural gas supply.  All costs incurred or benefits realized when these contracts are settled are included in the CGAC.

NSTAR Gas is subject to SQ metrics that measure safety, reliability and customer service and could be required to pay to customers a SQ charge of up to 2.5 percent of annual distribution revenues for failing to meet such metrics.  NSTAR Gas will not be required to pay a SQ charge for its 20182020 performance as it achieved results at or above target for all of its SQ metrics in 2018.2020.

Massachusetts: On July 7, 2014,Pursuant to Massachusetts enacted "An Act Relative to Natural Gas Leaks".  This act established a uniform natural gas leak classification standard for all Massachusetts natural gas utilities and a program that accelerates the replacement of aging natural gas infrastructure. The program enabled companies, including NSTAR Gas, to better manage the scheduling and costs of replacement.  The act also called for the DPU to authorize natural gas utilities to design and offer programs to customers that will increase the availability, affordability and feasibility of natural gas service for new customers.

Connecticut: Yankee Gas' December 2018 PURA approved rate case settlement agreement included an accelerated pipeline replacement cost recovery program. The Gas System Improvement (GSI) rate recovers accelerated pipeline replacement as well as other capital investment through an annual reconciliation. The Company filed its first GSI reconciliation on March 1, 2019 for rates effective April 1, 2019 and will continue to file annually on March 1 for rates effective April 1.

NSTAR Gas maintains a flexible resource portfolio consisting of natural gas supply contracts, transportation contracts on interstate pipelines, market area storage and peaking services. NSTAR Gas purchases transportation, storage, and balancing services from Tennessee Gas Pipeline Company and Algonquin Gas Transmission Company, as well as other upstream pipelines that transport natural gas from major natural gas producing regions in the U.S., including the Gulf Coast, Mid-continent region, and Appalachian Shale supplies to the final delivery points in the NSTAR Gas service area. NSTAR Gas purchases all of its natural gas supply under a firm, competitively bid annual portfolio management contract. In addition to the firm transportation and natural gas storage supplies discussed above, NSTAR Gas utilizes on-system LNG facilities to meet its winter peaking demands. These LNG facilities described below, are located within NSTAR Gas' distribution system and are used to liquefy and store pipeline natural gas during the warmer months for vaporization and use during the heating season. During the summer injection season, excess pipeline capacity and supplies are used to deliver and store natural gas in market area underground storage facilities located in Maryland and Pennsylvania. Stored natural gas is withdrawn during the winter season to supplement flowing pipeline supplies in order to meet firm heating demand. NSTAR Gas has firm underground storage contracts and total storage capacity entitlements of approximately 6.6 Bcf, of which 3.5 Bcf LNG storage is provided by Hopkinton LNG Corp. in facilities located in Hopkintontwo different locations in Massachusetts.

The PURA requires Yankee Gas to meet the needs of its firm customers under all weather conditions. Specifically, Yankee Gas must structure its supply portfolio to meet firm customer needs under a design day scenario (defined as the coldest day in 30 years) and under a design year scenario (defined as the average of the four coldest years in the last 30 years). Yankee Gas also maintains a flexible resource portfolio consisting of natural gas supply contracts, transportation contracts on interstate pipelines, off-system storage and its on-system 1.2 Bcf LNG storage facility in Connecticut to meet consumption needs during the coldest days of winter. Yankee Gas obtains its interstate capacity from the three interstate pipelines that directly serve Connecticut: the Algonquin, Tennessee and Iroquois Pipelines, which connect to other upstream pipelines that transport natural gas from major natural gas producing regions, including the Gulf Coast, Mid-continent, Canadian regions and Appalachian Shale supplies.

Based on information currently available regarding projected growth in demand and estimates of availability of future supplies of pipeline natural gas, each of NSTAR Gas, EGMA and Yankee Gas believes that participation in planned and anticipated pipeline and storage expansion projects will be required in order for it to meet currentthe long-term firm customer requirements in a reliable manner will necessitate a combination of pipeline, storage, and future sales growth opportunities.non-pipeline solutions.

The capacities of Aquarion’s sources of supply, and water treatment, pumping and distribution facilities, are considered sufficient to meet the present requirements of Aquarion’s customers under normal conditions. On occasion, drought declarations are issued for portions of Aquarion’s service territories in response to extended periods of dry weather conditions.

Eversource's offshore wind business includes ownership interests in North East Offshore and Bay State Wind, is anwhich together hold power purchase agreements (PPAs) and contracts for the Revolution Wind, South Fork Wind and Sunrise Wind projects, as well as offshore leases through BOEM. Our offshore wind projectprojects are being jointly developed by and constructed through a joint and equal partnership with Ørsted. This partnership also participates in new procurement opportunities for offshore wind energy in the Northeast U.S.

Eversource has a 50 percent ownership interest in North East Offshore, which holds the Revolution Wind and Denmark-based Ørsted.South Fork Wind projects, as well as a 257 square-mile ocean lease off the coasts of Massachusetts and Rhode Island. Eversource also has a 50 percent ownership interest in Bay State Wind, which holds the Sunrise Wind project. Bay State Wind's separate 300-square-mile ocean lease is located in a 300-square-mile area of the Atlantic Ocean approximately 25 miles south of the coast of Massachusetts adjacent to the North East Offshore area. In aggregate, the Bay State Wind and has the ultimate potential to generateNorth East Offshore ocean lease sites jointly-owned by Eversource and Ørsted could eventually develop at least 2,0004,000 MW of clean, renewable energy. Eversource and Ørsted each hold a 50 percent ownership interest in Bay State Wind. Bay State Wind has previously submitted proposals, and expects to participate in future solicitations, for offshore wind in Connecticut, Massachusetts, New York and Rhode Island based on each state's clean energy requirements.energy.

We project to make capital expenditures of $12.75$17.03 billion from 20192021 through 2023,2025, of which we expect $8.06$10.90 billion to be in our electric and natural gas distribution segments, $3.35$4.31 billion to be in our electric transmission segment and $0.62$0.78 billion to be in our water distribution segment. We also project to invest $0.72$1.05 billion in information technology and facilities upgrades and enhancements. These projections do not include any expected investments related to NPT orour offshore wind projects.  partnership.

Our credit facilities and indentures require that Eversource parent and certain of its subsidiaries, including CL&P, NSTAR Electric, PSNH, NSTAR Gas, EGMA, Yankee Gas, and Aquarion Water Company of Connecticut, comply with certain financial and non-financial covenants as are customarily included in such agreements, including maintaining a ratio of consolidated debt to total capitalization of no more than 65 percent. All of these companies currently are, and expect to remain, in compliance with these covenants.  

As of December 31, 2018, $801.1 million2020, $1.02 billion of Eversource's long-term debt, including $350.0$450.0 million, $250.0 million, $150.0 million, $50.0$282.0 million, and $1.1$40.2 million for Eversource parent, CL&P,NSTAR Electric, PSNH, Yankee Gas and Aquarion, respectively, will mature within the next 12 months.

CL&P, NSTAR Electric, PSNH, and several other New England electric utilities are stockholders in three inactive regional nuclear generation companies, CYAPC, MYAPC and YAEC (collectively, the Yankee Companies).  The Yankee Companies have completed the physical decommissioning of their respective generationnuclear power facilities and are now engaged in the long-term storage of their spent nuclear fuel.  The Yankee Companies have completed collection of their decommissioning and closurefund these costs through thelitigation proceeds received from the spent nuclear fuel litigation against the DOE and, have refunded amounts to their member companies.  These proceeds were used by the Yankee Companies to offset the decommissioning and closure cost amounts due from their member companies or to decrease theextent necessary, through wholesale, FERC-approved rates charged under power purchase agreements with several New England utilities, including CL&P, NSTAR Electric and PSNH. CL&P, NSTAR Electric and PSNH, and several other New England utilities.  The decommissioning rates charged by the Yankee Companies have been reduced to zero.  CL&P, NSTAR Electric and PSNH canin turn recover these costs from or refund proceeds to, their customers through state regulatory commission-approved retail rates. The Yankee Companies collect amounts that we believe are adequate to recover the remaining plant closure and fuel storage cost estimates for the respective plants. We believe CL&P and NSTAR Electric will recover their shares of these obligations from their customers. PSNH has recovered its total share of these costs from its customers.

We consolidate the assets and obligations of CYAPC and YAEC on our consolidated balance sheet because our ownership and voting interests are moregreater than 50 percent of each of these companies.  

We are regulated in virtually all aspects of our business by various federal and state agencies, including FERC, the SEC, and various state and/or local regulatory authorities with jurisdiction over the industry and the service areas in which each of our companies operates, including the PURA, which has jurisdiction over CL&P, Yankee Gas, and Aquarion, the NHPUC, which has jurisdiction over PSNH and Aquarion, and the DPU, which has jurisdiction over NSTAR Electric, NSTAR Gas, EGMA and Aquarion, and the NHPUC, which has jurisdiction over PSNH and Aquarion.

We are subject to various federal, state and local requirements with respect to water quality, air quality, toxic substances, hazardous waste and other environmental matters.  Additionally, major generation and transmission facilities may not be constructed or significantly modified without a review of the environmental impact of the proposed construction or modification by the applicable federal or state agencies.  

Each of the states in which we do business also has Renewable Portfolio Standards ("RPS")(RPS) requirements, which generally require fixed percentages of our energy supply to come from renewable energy sources such as solar, wind, hydropower, landfill gas, fuel cells and other similar sources.

Massachusetts' RPS program also requires electricity suppliers to meet renewable energy standards. For 2018,2020, the requirement was 23.36527.71 percent, and will ultimately reach 37.7539.31 percent in 2020.2025. NSTAR Electric is permitted to recover any costs incurred in complying with RPS from its customers through rates. NSTAR Electric also owns renewable solar power facilities. The RECs generated from NSTAR Electric's solar power facilities are sold to other energy suppliers, and the proceeds from these sales are credited back to customers.

We have recorded a liability for what we believe, based upon currently available information, is our reasonably estimable environmental investigation, remediation, and/or Natural Resource Damages costs for waste disposal sites for which we have probable liability. Under federal and state law, government agencies and private parties can attempt to impose liability on us for recovery of investigation and remediation costs at hazardous waste sites. As of December 31, 2018,2020, the liability recorded for our reasonably estimable and probable environmental remediation costs for known sites needing investigation and/or remediation, exclusive of recoveries from insurance or from third parties, was $64.7$102.4 million, representing 6063 sites. These costs could be significantly higher if additional remediation becomes necessary or when additional information as to the extent of contamination becomes available.

The most significant liabilities currently relate to future clean-up costs at former MGP facilities. These facilities were owned and operated by our predecessor companies from the mid-1800's to mid-1900's. By-products from the manufacture of natural gas using coal resulted in fuel oils, hydrocarbons, coal tar, purifier wastes, metals and other waste products that may pose a potential risk to human health and the environment. We currently have partial or full ownership responsibilities at former MGP sites that have a reserve balance of $50.1$92.2 million of the total $64.7$102.4 million as of December 31, 2018.2020. MGP costs are recoverable through rates charged to our customers.

For more than twenty years, published reports have discussed the possibility of adverse health effects from electric and magnetic fields ("EMF")(EMF) associated with electric transmission and distribution facilities and appliances and wiring in buildings and homes.  Although weak health risk associations reported in some epidemiology studies remain unexplained, most researchers, as well as numerous scientific review panels, considering all significant EMF epidemiology and laboratory studies, have concluded that the available body of scientific information does not support the conclusion that EMF affects human health.

In accordance with recommendations of various regulatory bodies and public health organizations, we reduce EMF associated with new transmission lines by the use of designs that can be implemented without additional cost or at a modest cost.  We do not believe that other capital expenditures are appropriate to minimize unsubstantiated risks.

Global climate change and greenhouse gas emission issues have received an increased focus from state governments and the federal government. The EPA initiated a rulemaking addressing greenhouse gas emissions and, on December 7,in 2009, issued a finding that concluded that greenhouse gas emissions are "air pollution" that endangers public health and welfare and should be regulated.  The EPA has mandated greenhouse gas emission reporting beginning in 2011 for emissions for certain aspects of our business including volume of gas supplied to large customers and fugitive emissions of SF6 gas and methane.

We are continually evaluating the regulatory risks and regulatory uncertainty presented by climate change concerns.  Such concerns could potentially lead to additional rules and regulations that impact how we operate our general utility business.  These could include federal "cap and trade" laws, carbon taxes, and fuel and energy taxes.  We expect that any costs of these rules and regulations would be recovered from customers.

Our website address is www.eversource.com.  We make available through our website a link to the SEC's EDGAR website (http://www.sec.gov/edgar/searchedgar/companysearch.html), at which site Eversource's, CL&P's, NSTAR Electric's and PSNH's combined Annual Reports on Form 10-K, combined Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and any amendments to those reports may be reviewed. Information contained on the Company's website or that can be accessed through the website is not incorporated into and does not constitute a part of this Annual Report on Form 10-K.  Printed copies of these reports may be obtained free of charge by writing to our Investor Relations Department at Eversource Energy, 107 Selden Street, Berlin, CT 06037.  

As evidenced by the global pandemic of the 2019 novel coronavirus (COVID-19), global pandemics result in widespread disruption to the overall economic market and outlook, which could cause various unfavorable impacts to our customers, vendors, employees, regulators, and operations and could adversely affect our financial results and liquidity.

We do not have any unresolved SEC staff comments.

As of December 31, 2018,2020, Eversource and our electric operating subsidiaries owned the following: