2025 SUSTAINABILITY REPORT (2025 SustainabilityReport)

Table of Contents

Overview

Advance Environmental Stewardship

Empower Our People

Engage Stakeholders and Communities

Execute with Integrity

Appendix

Additional Resources

2

Table of Contents Overview Advance Environmental Stewardship Empower Our People Engage Stakeholders and Communities Execute with Integrity Appendix Additional Resources 3

MPC AT A GLANCE

139 years

w3 million

THE BUSINESS OF MPC

Through our 139-year history, MPC has become a leading, integrated, downstream and midstream energy company.

We operate one of the nation's largest refining systems, where we process a wide variety of crude oils and condensate from various suppliers to produce numerous refined products. We sell these products to wholesale marketing customers, buyers on the spot market, independent entrepreneurs who operate primarily Marathon® branded outlets and direct dealers who operate locations mainly under the ARCO® brand.

Our renewable diesel assets process lower-carbon feedstocks into renewable diesel that, similarly, is sold to wholesale marketers, buyers on the spot market and direct dealers who operate locations mainly under the ARCO® brand.

in the energy business,

innovating and evolving since 1887

11.2 billion

standard cubic feet per day of natural gas processing capacity

w21,OOO

miles of pipeline owned, leased or with ownership interest

w9,OOO

North American retail and marketing locations

MPC's master limited partnership formed to own, operate, develop and acquire midstream energy infrastructure

w2.8 billion

gallons of renewable fuels delivered in 2025

546

transport trucks owned and operated

2 strong brands

Marathon® and ARCO®

barrels per calendar day of

crude oil refining capacity

35O

vessels and barges owned and operated through marine business

4O million

barrels of terminal storage capacity

w14,1OO

rail tank cars

Our midstream operations, primarily conducted through MPLX LP, gather, transport, store and distribute crude oil, refined products - including renewable diesel - and other hydrocarbon-based products via refining logistics assets, pipelines, terminals, towboats and barges. We also gather, process and transport natural gas and transport, fractionate, store and sell natural gas liquids (NGLs).

' To view a map of our operations, please visit the Operations page of our website.

OUR ENERGY CARRIES LIFE FORWARD™

Fuel for cars, trucks, buses,

aircraft, trains and ships

Fuel for steam and electricity

generation, heating and cooling

Fuel for outdoor heaters,

grills, cooktops and lanterns

Asphalt for roads and roofing

Ingredients for other

product manufacturing, such as plastics, fertilizers, synthetic fibers, cosmetics, pharmaceuticals, solvents and aerosol propellant

The energy and products we produce, process and transport support industrial, infrastructure and residential needs across a broad value chain, including:

Table of Contents Overview Advance Environmental Stewardship Empower Our People Engage Stakeholders and Communities Execute with Integrity Appendix Additional Resources 4

A MESSAGE

FROM OUR CEO

At MPC and MPLX, sustainability means advancing environmental stewardship, empowering our people, engaging meaningfully with stakeholders and communities, and operating with integrity. Through this work, we create shared value for our stakeholders while producing the energy on which we all depend.

In times of market volatility, reliable energy is top of mind for many. When our facilities operate safely, reliably and with strong environmental performance, they help support the availability of affordable, reliable fuels - an important component of the shared value we strive to create. I am proud that our talented and dedicated workforce achieved record safety and environmental performance in 2025.

We delivered our best companywide safety performance in four years, including a 16% year-over-year improvement in our Process Safety Events score. Excellence in process safety requires constant vigilance across our operations and continuous improvement in our management systems. It remains one of our highest priorities.

We also achieved a seven-year low in companywide OSHA recordable injuries. In 2025, eight of our 13 refineries were recognized with safety awards from the American Fuel & Petrochemical Manufacturers, and our Detroit refinery again received AFPM's highest honor - the Distinguished Safety Award - for the fourth time, including back-to-back wins in 2024 and 2025. Detroit is now one of only seven refineries to earn this recognition in consecutive years over the past 35 years. Additional details on important third-party safety recognitions are included on Page 26 of this report.

These results provide strong evidence that our safety culture, programs and collective mindset are delivering measurable progress. At the same time, we know there is more work ahead. We must remain focused on our goal that every employee goes home safely at the end of each shift.

"When we talk about safety, we do not view it as a set of rules that we must follow but rather safety is a culture that each and every one of us must uphold every day, in every decision we make, doing the work the right way every time, every day to protect our people, our communities and the reputation of this great industry."

T. Mannen

Maryann T. Mannen

n, President and

ecutive Officer,

MPLX,

Chairma , President and Chief Ex cutive Officer, MPC and MPLX,

ng an all-

e Leadership

orum

addressi g an all-employe Leadership Insights Forum

On the environmental front, in 2025 we achieved our 2030 goal of reducing Scope 1 and 2 greenhouse gas emissions intensity by 30% from 2014 levels. Our 2035 target of a 38% reduction remains firmly in our sights. We also met our target to reduce freshwater withdrawal intensity by 20% from 2016 levels five years ahead of schedule. MPLX has achieved a 68% reduction in methane emissions intensity from 2016 levels, and MPLX subsidiary Marathon Pipe Line achieved its biodiversity target by cultivating sustainable landscapes on more than 10,000 acres of pipeline right of way. This achievement supports long-term environmental health while also contributing to safe pipeline operations.

Reflecting our deep expertise in energy efficiency and our longterm investments in this area, MPC has earned more ENERGY STAR® refinery certifications than all other U.S. refiners combined. In 2025, our Salt Lake City refinery earned its first certification and joined the ranks of these certified facilities. Marathon Pipe Line also achieved its first ENERGY STAR Challenge for Industry recognition for its Los Angeles Basin Area site in 2025 - a first for the pipeline industry.

Our environmental stewardship work will continue through mature, embedded programs focused on energy efficiency, greenhouse gas reductions, water stewardship and biodiversity.

Marathon will celebrate its 140-year anniversary in 2027, and throughout that history we have remained committed to continuous improvement. We have made substantial progress over many decades, and the modern era provides a clear view of the advances we have made in safety and environmental performance over the last quarter-century. In the last 25 years, we have reduced criteria air pollutant emissions at the facilities that now comprise our refining fleet by approximately 56%; reduced Marathon OSHA recordable injury rates by approximately 79%; and reduced Designated Environmental Incidents by approximately 76%1. This performance is especially noteworthy given the significant growth and evolution of our company and operations during that time.

Our over 18,000 employees are the backbone of this company and central to our success. One way we create shared value with our employees, both today and for the long term, is through competitive compensation and benefits. In 2025, 95% of eligible employees contributed to our 401(k) thrift plan, supported by an employer match of up to 7%. This participation reflects the value employees place on the tools we provide to help support their financial well-being.

Our employees also demonstrate deep engagement and generosity in their communities. In 2025, they reported approximately 60,000 volunteer hours and joined with MPC, MPLX and our fundraising partners to invest approximately $35 million across more than 4,100 nonprofit organizations. This is a powerful illustration of shared value in action.

A key enabler of our sustainability accomplishments is our strong governance. Shared value is created through disciplined, values-rooted execution. The Boards of MPC and MPLX and our executive team take seriously their responsibility to uphold the governance frameworks that support our long-term success.

We expect our entire workforce to safeguard the reputation that generations of employees have helped build and to speak up when they have concerns. In doing so, they help protect the company for today's employees and for future generations of employees and stakeholders. In 2025, just over 10% of employees responded to a companywide poll in which 99% said MPC clearly communicates its expectations for ethical behavior, and 95% said they feel safe speaking up. In addition, 90% said they feel confident something would be done about unethical behavior when reported. We will continue working to improve this metric, and I am encouraged by the personal pride and shared ownership employees demonstrate for MPC and MPLX.

The programs and accomplishments presented in this year's Sustainability Report are a source of great pride. I invite you to explore these pages and learn more about the many ways MPC and MPLX are advancing sustainability and creating shared value with our stakeholders.

Sincerely,

Maryann T. Mannen

Chairman, President and Chief Executive Officer MPC and MPLX

1 Does not include former Andeavor operations, as Designated Environmental Incidents is a metric proprietary to Marathon.

Table of Contents

Overview Advance Environmental Stewardship

Empower Our People

Engage Stakeholders and Communities Execute with Integrity

Appendix

Additional Resources

5

2O25 SUSTAINABILITY HIGHLIGHTS

1O,215 acres

2O% reduction

3O% reduction

68% reduction

in methane emissions intensity from 2O16 levels

American Fuel & Petrochemical Manufacturers Distinguished Safety Award

M34.5 million

Top 1OO Internship Programs

Top Energy Company

Dow Jones

Best-in-Class Indices

Six U.S. EPA ENERGY STAR®

refinery certifications

Lowest number of

Tier 3 and 4 Designated Environmental Incidents

in seven years

Lowest OSHA Recordable Injury Rate

Table of Contents

Overview

Advance Environmental Stewardship

Empower Our People

Engage Stakeholders and Communities

Execute with Integrity

Appendix

Additional Resources

6

OUR APPROACH TO SUSTAINABILITY

3O%

BY

2O3O

At MPC and MPLX, our commitment to sustainability means working to create shared value with our stakeholders as we produce affordable, reliable energy. We do this by advancing environmental stewardship, empowering our people, engaging with stakeholders and communities, and executing with integrity. Our sustainability-driven approach supports our relentless commitment to continuous improvement as we contribute to an evolving energy industry.

2O25

SUSTAINABILITY-RELATED TARGETS

Scope 1 and 2 GHG Emissions Intensity

(tonnes CO2e/thousand boe input)

• 2035 Goal ● 2030 Goal ● Progress

  Methane Emissions Intensity

  (methane-scf/natural gas input-scf)

  • 2030 Goal ● Progress

    68%

    75%

    
    
    

    38%

    BY

    2O35

    AND

    We continue to make strong progress toward our sustainability commitments, achieving or exceeding several key targets ahead of schedule through focused execution and disciplined performance.

    In 2025, we met our 2030 Scope 1 and 2 GHG emissions intensity reduction target, achieving a 30% decrease from our 2014 baseline. We also met our 2030 freshwater withdrawal intensity goal, achieving a 20% reduction from our 2016 baseline. Achieving this target helps reduce operational exposure to water-related risks while delivering more efficient water use across operations. Both of these targets were achieved five years ahead of schedule.

    Lastly, we surpassed our 10,000 acre 2025 biodiversity goal, applying sustainable landscapes to 10,215 acres of compatible rights of way.

    These results reflect the effectiveness of our strategy and the disciplined execution of these initiatives.

    ' For more information on the underlying data for our targets, see our Performance Data onPage 48.

    We are committed to

    reducing our carbon footprint and implementing practices that conserve natural resources and reduce environmental impacts.

    We prioritize safety and are

    dedicated to cultivating a safe, collaborative and inclusive work environment that supports the growth and success of our people.

    We are committed to

    building relationships in our communities, consistently pursuing opportunities to create shared value with our stakeholders.

    We are committed to

    integrating sustainability in our decision-making and upholding accountable and transparent governance.

    
    
    

    3O%

    3O%

    AND

    38%

    Y

    2O3O

    Y

    2O35

    
    
    

    3O% reduction of Scope 1 and 2 GHG emissions intensity by 2030 and

    38% reduction by 2035 from 2014 levels

    75% reduction of MPLX methane emissions intensity by 2030 from 2016 levels

    Biodiversity - Sustainable Landscapes

    (acres)

    • 2025 Goal ● Progress

Freshwater Withdrawal Intensity

(megaliters/million boe input)

• 2030 Goal ● Progress

  1O,215 acres 2O%

  w1O,OOO

  acres

  2O%

  
  
  

  Apply sustainable landscapes to w1O,OOO ACRES (w5O%) of compatible MPL rights of way by the end of 2025

  2O% reduction of freshwater withdrawal intensity by 2030 from 2016 levels

  Table of Contents Overview Advance Environmental Stewardship Empower Our People Engage Stakeholders and Communities Execute with Integrity Appendix Additional Resources 7

  STAKEHOLDER ENGAGEMENT AND SHARED VALUE

  At MPC and MPLX, we are committed to creating shared value for our stakeholders, including our shareholders, employees, customers, business partners, government agencies and the communities where we live and work. Our sustainability

  2O25 BY THE NUMBERS

  strategy is informed by two-way dialogue and a desire to understand the issues and trends facing our company and industry. We consistently seek stakeholder input and, where appropriate, incorporate it into our sustainability approach.

  Our People

  $4 billion+

  paid in wages and benefits to 18,500+

  employees

  Shareholders

  52%

  OF SHARES OUTSTANDING

  participated in engagements with our company

  Customers

  w3.7

  million

  barrels per day of refined products sold to 5,200+ customers

  Business Partners

  w$1O billion

  paid to 8,300+ suppliers and business partners for goods and services'

  Communities

  w$34.5 million

  invested in the communities in which we operate through company contributions, our employees and fundraising partners

  Governments

  w$16.1 billion

  paid in taxes, contributing to national, state and local economies²

  HOW WE ENGAGE

  • All-employee Leadership Insights Forums

  • CEO

    communications

  • Code of Business Conduct

  • Employee Network Groups

  • Integrity Helpline

  • Performance management

  • Regular employee communications

  • Safety meetings

  • Training and career development

  • Wellness programs

  • Annual Shareholder Meeting

  • Digital communications, including company news releases, Sustainability Report and topical reports

  • Industry conferences and presentations

  • One-on-one meetings

  • Quarterly earnings calls

  • Company events and meetings

  • Global, regional and local industry events, forums and conferences

  • Working groups to advance best practices

  • Business partner reviews

  • Contract management

  • Sourcing process

  • Strategic partnership management

  • Supplier audits

  • Supplier Code of Conduct

  • Supplier diversity program

  • Supplier recognition awards

  • Community Advisory Panels and Councils

  • Community engagement and board representation

  • Community hotlines

  • Community surveys

  • Company and employee contributions, company match programs and company-led fundraisers

  • Employment fairs

  • Facilitation of community events

  • Facility tours

  • Focus groups

  • Landowner events

  • Sponsorships

  • Sustainability Highlights brochures

  • Websites, news and social media

  • Advocacy

  • Collaboration on community investment projects

  • Facility tours

  • Industry and trade association representation

  • Policy development

  • Regulatory and permitting compliance

  • Regulatory audits

  • Sustainability Highlights brochures

    1 Excludes crude/feedstock purchases and third-party logistics payments.

    2 Includes sales, use, excise taxes.

    
    
    

    Table of Contents Overview Advance Environmental Stewardship Empower Our People Engage Stakeholders and Communities Execute with Integrity Appendix Additional Resources 8

    We are committed to reducing our carbon footprint and implementing practices that conserve natural resources and reduce environmental impacts.

    9 Lowering Our C"rbon Footprint

    13 Conserving N"tur"l Resources

    
    
    

    Table of Contents Overview Advance Environmental Stewardship Empower Our People Engage Stakeholders and Communities Execute with Integrity Appendix Additional Resources 9

    LOWERING OUR

    CARBON FOOTPRINT

    We are committed to reducing the carbon footprint of our operations and the products we manufacture through energy-efficiency improvements that enhance performance and long-term resiliency. We work to optimize our assets, strategically invest in emerging technologies, expand our natural gas business and collaborate across sectors to drive efficiency improvements.

    Scope 1 and 2 GHG Emissions

    In 2020, we adopted a companywide Scope 1 and 2 GHG emissions intensity reduction target of 30% below 2014 levels by 2030. As we progressed toward this goal, we expanded our commitment in 2024 and set a new target to reduce Scope 1 and 2 GHG emissions intensity 38% from 2014 levels by 2035.

    In 2025, we achieved our 2030 target. We delivered a 30% reduction in emissions intensity from our 2014 baseline five years ahead of schedule - and we continue to make progress toward our 2035 target.

    We calculate emissions intensity by aggregating Scope 1 GHG emissions (direct emissions from our operations) and Scope 2 GHG emissions (indirect emissions from purchased electricity and steam) across our operations and dividing by total manufacturing inputs. Because our manufacturing sites process a wide range of inputs - including crude oil, natural gas, natural gas liquids and renewable feedstocks - we normalize these inputs using a common energy basis of barrels of oil equivalent (boe) to ensure comparability.

    Our progress reflects consistent execution and long-term focus. Since 2014, we have driven sustained Scope 1 and 2 GHG emissions intensity reductions. Energy efficiency initiatives have avoided nearly 1 billion Btu per hour of

    Scope 1 and 2 GHG Emissions Intensity

    (tonnes CO2e/thousand boe input)

    • 2035 Goal ● 2030 Goal ● Progress

3O%

3O%

BY

2O3O

3O%

Y 2O3O

AND

AND

38%

BY

2O35

38%

Y 2O35

3O% reduction of Scope 1 and 2 GHG emissions intensity by 2030 and 38% reduction by 2035 from

2014 levels

Scope 1 and 2 GHG Emissions Intensity

(tonnes CO2e/thousand boe input)

29.9

3O

DELIVERING ON OUR COMMITMENT

We are committed to reducing GHG emissions intensity through multiple initiatives, including:

• Improving energy efficiency through our Focus on Energy program

• Reducing methane emissions through targeted mitigation and asset optimization efforts

• Expanding MPLX Natural Gas and NGL Services to support operational diversification and lower-carbon intensity assets

• Optimizing renewable fuels production

  In 2025, we achieved our 2030 target to reduce Scope 1 and 2 GHG emissions intensity by 30% from 2014 levels, demonstrating the impact of energy-efficiency initiatives and continued focus on operational performance.

  Capital Allocation

  At MPC and MPLX, we invest to strengthen the competitive position of our assets and enhance long-term resiliency. Today, we are focused on optimizing our core refining and logistics portfolio while expanding our natural gas and NGL value chain and advancing value-enhancing projects.

  MPC and MPLX allocate capital between sustaining and growth capital categories. Sustaining capital - which supports safe, reliable and compliant operations - represents approximately 20% of MPC and MPLX's anticipated 2026 capital spend. The remaining 80% is growth and value-enhancing capital, which we deploy in areas that improve operating performance, support our most competitive assets and enable the build-out of our lower-carbon intensity natural gas value chain.

  These investments enhance our operational efficiency and resilience while positioning the company to continue to play a vital role in the evolving energy system.

  energy use and generated more than $28 million in savings in 2025, demonstrating the value of disciplined energy management. We have also consistently earned ENERGY STAR® awards and certifications from the U.S. Environmental Protection Agency, providing third-party validation of our governance, performance and commitment to continuous improvement in energy efficiency.

  22.9 22.4 21.7 21.4 2O.9

  2O

  1O

  O

  2O14 2O21 2O22 2O23 2O24 2O25

  3O% REDUCTION GOAL BY 2030

  38% REDUCTION GOAL BY 2035

  
  
  

  Table of Contents Overview Advance Environmental Stewardship Empower Our People Engage Stakeholders and Communities Execute with Integrity Appendix Additional Resources 10

  Energy Management

  Energy efficiency is a critical driver to reduce greenhouse gas emissions and support long-term operational resilience and financial performance. By identifying and implementing

  cost-effective energy conservation opportunities, we lower operating costs, reduce energy consumption and decrease energy-related emissions across our operations.

  Focus on Energy

  Our companywide Focus on Energy program serves as the primary framework for advancing energy efficiency across our refining operations, renewable fuels facilities and MPLX assets, including natural gas and NGL services, terminals and pipeline systems. The program takes a holistic, data-driven approach to identify efficiency opportunities, improve performance and

  ENERGY STAR® ACCOMPLISHMENTS

  Through the strength of our Focus on Energy program, we have established a culture of continuous improvement in energy efficiency. Our industry-leading accomplishments underscore our position as a leader in energy efficiency across refining and midstream operations. MPC has earned more ENERGY STAR® refinery certifications than all other U.S. refiners combined, reflecting sustained high performance. In 2025, our Salt Lake City refinery achieved its first certification, further expanding this track record.

  Our leadership extends beyond refining. MPLX's Bluestone natural gas processing facility became the first facility in the U.S. natural gas processing sector to achieve the ENERGY STAR Challenge for Industry, and our Los Angeles Basin booster station was the first facility in the U.S. pipeline industry to earn this designation. These achievements demonstrate our ability to drive energy efficiency across a diverse portfolio of assets and reinforce our commitment to operational excellence.

  SPOTLIGHT ON

  M"r"thon Pipe Line³s Los Angeles B"sin Are"

  Marathon Pipe Line's (MPL) L.A. Basin Area site achieved the U.S. Environmental Protection Agency's (EPA) ENERGY STAR® Challenge for Industry in 2025. Meeting the Challenge requires industrial facilities to reduce their energy intensity by at least 10% within a five-year period.

  MPL's Mobil booster pump station in Southern California surpassed the target with a 17.1% reduction from its established baseline within one year. This success came

  manage energy-related risks.

  Focus on Energy is built on a set of core elements that support continuous improvement. These elements include energy performance standards, digitalization of energy data systems, maintenance and reliability programs, energy management systems and enhanced data collection and analysis. These elements are reinforced through strong governance, dedicated leadership and a culture of accountability that enables measurable, sustained progress.

  The program is implemented at all 13 of our refineries, our renewable diesel facilities and select MPLX facilities. Site-specific energy coordinators play a critical role to advance performance by:

• Establishing and tracking key energy performance metrics

• Identifying and evaluating efficiency opportunities and benchmarking performance

• Developing and implementing energy conservation road maps

• Integrating energy efficiency into project design and operations

• Supporting operator awareness and training

  Through Focus on Energy, we have achieved meaningful results, including avoiding nearly a billion Btu per hour of energy use and generating more than $28 million in savings in 2025, equivalent to the annual energy use of approximately 60,000 homes or 100,000 gasoline-powered passenger vehicles. These efforts support both operational efficiency and emissions-reduction objectives.

  Certified F"cilities

  6 facilities recognized for energy-efficient performance ranking in the top 25% of nationwide peer facilities

  MPC Refining

  Anacortes, Washington (6 years)

  Canton, Ohio (20 years)

  Garyville, Louisiana (20 years)

  Robinson, Illinois (11 years)

  St. Paul Park, Minnesota (8 years)

  Salt Lake City, Utah (1st year)

  The company has earned more ENERGY STAR® refinery certifications than all other U.S. refineries combined1, reflecting sustained leadership in energy efficiency across the refining sector.

  MPC

  79

  51

ALL OTHER

U.S. REFINERIES

1 Through 2025 certification year.

14 facilities recognized for energy-efficiency performance through a 10% reduction in energy intensity

MPLX Natural Gas and NGL Services

• Bluestone Gas Processing Facility (Evans City, Pennsylvania)

  MPLX Crude Oil and Product Logistics

• Los Angeles Basin booster station (California)

• 12 terminals across five states: Alaska (Anchorage), Illinois (Champaign), Indiana (Mt. Vernon, Muncie), Michigan (Jackson, Lansing), Ohio (Cincinnati, Youngstown), Tennessee (Nashville - 51st Terminal, Bordeaux, Downtown Terminal) and West Virginia (Charleston)

  Our Bluestone Gas Processing Facility and Los Angeles booster station are the first and only facilities in their sector to achieve the challenge.

  We continue to pursue energy efficiency improvements across our operations with 10 additional facilities now entered in the Challenge for Industry program.

  from modifying a pump by removing an impeller stage, to prevent the pump from using more energy than required for its function. This project delivered an annual energy avoidance of 6.375 billion Btu, increasing competitiveness of the site by reducing electricity costs.

  MPL's first ENERGY STAR® Challenge for Industry and a first for the U.S. pipeline industry

  An"cortes Industri"l Showc"se

  Our Anacortes, Washington, refinery hosted an ENERGY STAR® Industrial Showcase for regulatory agencies' staff, elected officials, area Tribal members, local utility board members and other key stakeholders in recognition of its achievements in energy-management practices. Their efforts have helped earn six consecutive ENERGY STAR certifications.

  Employees conducted refinery tours and staffed exhibit booths to explain initiatives that are helping advance sustainability at the Anacortes refinery. These include engineering projects that have reduced emissions of nitrogen oxides, use of software to identify the most efficient ways of managing process equipment and an LED lighting initiative.

  
  
  

  Table of Contents Overview Advance Environmental Stewardship Empower Our People Engage Stakeholders and Communities Execute with Integrity Appendix Additional Resources 11

  Methane Emissions

  MPLX Natural Gas and NGL Services manages methane emissions through a measurement-informed, data-driven Focus on Methane program. As this approach has matured, Methane Matters represents the next phase of our strategy - building on progress to address changing market expectations, advancing technologies and evolving regulations. Our strategy emphasizes continuous improvement, operational accountability, environmental performance and progress in emissions management.

  In 2022, we expanded our methane intensity reduction target to further strengthen performance and risk management, with a goal to reduce methane intensity 75% by 2030 relative to a 2016 baseline. Through 2025, we have achieved a 68% reduction, reflecting sustained progress across our operations.

  Embedding Meth"ne Aw"reness in Oper"tions

  Methane Matters reinforces consistent, field-level practices that support emissions reduction across our operations:

  Minimize 6nd Monitor

• Maintain awareness of equipment performance and respond to upsets

• Understand likely emission sources across operations

• Limit venting and use it only as a last resort

  Fix 6nd Prevent

• Inspect and maintain equipment to support reliable operations

  Methane Emissions Intensity

  (methane-scf/natural gas input-scf)

  • 2030 Goal ● Progress

    68%

    75%

    75% reduction of MPLX methane emissions intensity by 2030 from 2016 levels

    MPLX Methane Emissions Intensity

    (methane-scf/natural gas input-scf)

    APPROACH TO MANAGING METHANE

    Our methane management strategy is structured around four core pillars:

    Detect

    We prioritize early identification of methane emissions through a comprehensive suite of detection technologies, supporting a measurement-informed inventory and faster response times:

• Satellite monitoring

• Aerial surveys

• Ground-based continuous monitors

• Manual leak detection programs

• Stack testing and performance data

  Mitigate

  We target emissions reductions through equipment upgrades, operational improvements and proactive maintenance, including:

• Reducing methane slip from combustion sources

• Replacing and maintaining compressor rod packing

• Deploying engine upgrade kits during overhauls

• Optimizing fuel use through programs such as Equipment, Compression Health & Optimization (ECHO)

  These actions support targeted emissions reductions while improving system reliability and efficiency.

  Report

  Transparent, measurement-based reporting is central to our approach. We are committed to developing emissions

  Me"surement-Driven Perform"nce

  Our measurement-informed approach enables more accurate emissions quantification, improved decision-making and targeted mitigation. By integrating advanced technologies with operational data, we enhance the accuracy, consistency and transparency of our emissions reporting.

  Through MPLX's program, we have implemented measures that are anticipated to enable approximately 16,000 tonnes per year of methane emissions reductions and enhanced system efficiency relative to a 2016 baseline.

• Take ownership of identified issues

• Complete repairs in a timely manner to reduce emissions

  Innov6te 6nd Improve

• Deploy new technologies to enhance detection and mitigation

• Design systems to reduce emissions at the source

• Continuously improve work practices through data and experience

O.O4O%

O.O2O%

O.OOO%

O.O37%

O.O2O%

O.O18%

O.O16% O.O15%

O.O12%

75% REDUCTION GOAL BY 2030

inventories that reflect both performance and evolving measurement capabilities, enabling stakeholders to understand our progress and challenges.

Engage

Collaboration is a key component of our strategy. We work with industry peers, regulators and research institutions to advance best practices and accelerate technology development.

Partnerships such as the Appalachian Methane Initiative - led by the Energy Emissions Modeling and Data Lab, Colorado State University's Methane Emissions Technology Evaluation Center and The Environmental Partnership - support innovation and the

2O16 2O21 2O22 2O23 2O24 2O25

adoption of data-driven solutions.

Table of Contents

Overview

Advance Environmental Stewardship

Empower Our People

Engage Stakeholders and Communities

Execute with Integrity

Appendix

Additional Resources

12

KEY

OBJECTIVES:

Maintain safe and reliable operations across our renewable fuels facilities while continuously optimizing to maximize returns.

Identify and deploy

innovative and emerging technologies that enhance business performance by offering attractive returns, improving reliability, reducing costs and minimizing environmental impact.

Hydrocarbon fuels remain essential to today's economy and are expected to play a critical role for the foreseeable future. Improving how these fuels are produced and delivered is foundational to advancing environmental stewardship and key to meeting the needs of global energy markets. At the same time, our investments enable us to produce lower-carbon intensity products and support emissions reductions across the transportation sector.

In 2025, we were among the largest suppliers of renewable fuels in the United States, delivering approximately 2.8 billion gallons to customers. This volume is estimated to have avoided approximately 16 million tonnes of CO, emissions from transportation1.

Arbor Energy

RENEWABLE FUELS INVESTMENTS

M"rtinez Renew"bles

Martinez, California

• Joint venture with Neste Corporation

• Among the largest renewable diesel facilities in the world

• 730 million gallons per year capacity

Green Bison Soy Processing

Spiritwood, North Dakota

• Joint venture with ADM

• Produces refined soybean oil

• '600 million pounds per year capacity

• Enough feedstock for '75 million gallons of renewable diesel per year

Dickinson Renew"ble Diesel F"cility

Dickinson, North Dakota

• Produces renewable diesel and naphtha

• 184 million gallons per year capacity

LF Bioenergy

Commercial operations at seven facilities across the U.S.

• MPC has 49.9% interest in LF Bioenergy

• Produces renewable natural gas from organic waste on dairy farms

Renewable Feedstock Responsible Sourcing

We implement a risk-based approach to responsibly source feedstocks for our renewable diesel facilities. We evaluate current and prospective suppliers, countries of origin and new feedstock varieties. Reviews of suppliers are conducted to evaluate their alignment with our Supplier Code of Conduct. This may include an interview to obtain supplier-specific information or to address questions regarding a commodity or its origins. Before new renewable feedstocks are processed at our facilities, we evaluate a variety of information, including information on environmental, regulatory and human rights topics. We continue to monitor the sustainability of our renewables sourcing practices.

Emerging power-generation technologies are playing a role in shaping a lower-carbon energy future. MPC has invested in Arbor Energy2, a company developing next-generation, zero-emission power systems. Arbor Energy's technology combines advanced turbine design with innovative combustion processes to deliver scalable, fuel-flexible power with the potential for carbon-neutral or carbon-negative operation with use of carbon sequestration or the use of waste biomass. While early in development, this investment reflects our commitment to identifying and supporting technologies that could play a role in the evolving energy landscape.

Aquanta Vision

Digital advances are transforming how emissions are identified and managed across industrial operations. MPC has invested in Aquanta Vision3, a company developing advanced methane detection software. Aquanta Vision's technology enhances optical gas imaging inspections by applying automated, physics-based algorithms that improve the accuracy and speed of leak detection using existing equipment. By enabling real-time identification and visualization of methane emissions across a range of inspection methods, this technology has the potential to strengthen emissions monitoring, support more timely repairs and reduce overall emissions. Our investment reflects our interest in scalable digital solutions that enhance measurement capabilities and support more efficient, data-driven operations.

Square Robot

Improving the safety and efficiency of routine inspection activities is critical to maintaining reliable operations and protecting the health and safety of our workforce. In 2025, we expanded our relationship with Square Robot4, a company that develops robotic systems for the inspection of aboveground storage tanks. These robots are designed to operate while a tank remains in service, enabling more frequent inspections without requiring tank shutdowns or entry into confined spaces by personnel. By improving inspection efficiency and reducing operational disruptions, this technology has the potential to enhance safety, lower emissions associated with maintenance activities and strengthen the integrity management of critical infrastructure.

Via Separations

MPC has invested in Via Separations5, a company advancing next-generation membrane filtration technology for industrial applications. Via Separation's technology replaces energy-intensive, heat-driven separation processes with electrified filtration systems that can significantly reduce energy use while enhancing operational reliability and performance. With thermal separations representing a major source of industrial energy demand, innovations like Via Separation's have the potential to lower emissions and improve efficiency across MPC's existing operations through scalable solutions.

w2.8

billion

gallons of renewable fuels delivered to customers in 2O25

INNOVATION ECOSYSTEM

Advancing solutions for environmental and operational benefits requires ongoing coordination across a broad innovation ecosystem. MPC collaborates with several leading academic institutions and research networks to this end.

These include the Massachusetts Institute of Technology's Industrial Liaison Program, which connects industry with cutting-edge research, faculty expertise and startup innovation. In Houston, MPC participates in a dynamic regional ecosystem that brings together industry, academia and entrepreneurs through initiatives associated with Rice University - the Ion Innovation District and Greentown Labs

- North America's largest climatetech incubator. These platforms foster collaboration across sectors to identify, develop and scale innovative solutions that enhance operational performance, strengthen emissions management and support a more sustainable energy future.

1 MPC estimated avoided emissions using fuel carbon intensity values generated per the California Air Resources Board Low Carbon Fuel Standard life-cycle analysis models and documentation (i.e., CA-GREET3.0).

2 https://arbor.co/

3 https://www.aquantavision.com/

4 https://squarerobot.com/

5 https://viaseparations.com/

Table of Contents

Overview

Advance Environmental Stewardship

Empower Our People

Engage Stakeholders and Communities

Execute with Integrity

Appendix

Additional Resources

13

CONSERVING

NATURAL RESOURCES

Guided by our Core Value of Safety and Environmental Stewardship, we strive to be responsible stewards of the environment while meeting society's current and future energy needs. We recognize our business activities have potential to affect ecosystems and communities, and we work diligently to manage and mitigate any impacts. We are committed to minimizing environmental impacts through advanced technologies, practices and investments that support the conservation of natural resources.

Our Operational Excellence Management System (OEMS) is third-party reviewed for alignment with the RC14001® standard, and 100% of our operations are in scope. The standard incorporates our environmental stewardship policies, including our responsibility to evaluate and minimize environmental impact, train our employees on environmental management best practices and maintain open communication with stakeholders.

' Learn more in the OEMS section on Page 43.

We link environmental performance to employee compensation and measure it using the Designated Environmental Incident (DEI) metric. It tracks three categories of environmental events: unplanned releases to air, land and water; environmental permit exceedances; and agency enforcement actions. We assess DEI severity using a four-tier framework. Tiers 1 and 2 indicate lower severity, and Tiers 3 and 4 indicate higher severity.

Tier 3 and 4 DEIs

(count)

2O19

2O2O

2O21

2O22

2O23

69

2O24

2O25

47

45

Lowest number of Tier 3 and 4 DEIs in the past seven years

52

55

5O

85

Our priority is to prevent all incidents. As a precaution, we invest in our response capabilities and preparedness training to ensure our teams have the knowledge and resources needed to help mitigate and manage impacts to people and the environment should an event occur. In these instances, we conduct a thorough review of the event and apply lessons learned to strengthen our processes and practices. Findings from completed investigations have informed process improvements and other measures designed to address root causes and reduce the number of incidents.

We take proactive steps to protect diverse plant and animal species and preserve habitats in areas where we operate. Our OEMS provides a framework for assessing how our activities may affect ecosystems and for implementing the mitigation measures needed to reduce those impacts.

Our formal Commitment to Biodiversity outlines our approach and practices. Governed by executive leadership and adopted companywide, it emphasizes that we seek first to avoid, then minimize, and, where appropriate, offset impacts to biodiversity. We recognize that operating within communities is a privilege, and we collaborate with tribal and local communities, business partners, and relevant state and federal regulatory agencies, including the

U.S. EPA, U.S. Fish and Wildlife Service, U.S. Bureau of Land Management and U.S. Army Corps of Engineers.

' To view our formal Commitment to Biodiversity, please visit our website.

75O+

ACRES OF HABITAT

9 HABITAT

PROGRAMS

1

3

5

Certified

Gold

Certified

Silver

Certified

CERTIFIED

PROGRAMS SUPPORT

Habitat Management

Species

Monitoring

Conservation

Education

29,3OO+

hours of environmental training for MPC employees in 2O25.

Wildlife Habitat Council Certification®, powered by Tandem Global, is the only voluntary sustainability standard designed to recognize and promote biodiversity enhancement and conservation education on corporate landholdings. Our certifications cover:

Our policies and practices govern asset siting, construction, operation, maintenance and decommissioning. They establish requirements and practices intended to help minimize potential impacts on the environmental quality of habitats in and adjacent to our operational areas. These policies are aligned with the International Finance Corporation's Performance Standards on Environmental and Social Sustainability.'

Throughout the asset life cycle, we prioritize impact avoidance on ecologically sensitive areas. Where land disturbance is unavoidable, we apply recognized best management practices to minimize and mitigate impacts. When complete restoration is not feasible, we offset residual impacts through approved conservation mitigation banks and other mechanisms that support the long-term protection of comparable sensitive habitats.

At e6ch st6ge of the 6sset life cycle, we:

• Identify and engage impacted stakeholders to solicit feedback, which becomes part of our decision-making process.

• Conduct location-specific risk assessments, as appropriate, including desk and field studies, to evaluate nature dependencies and impact to biodiversity, natural resources and land use.

• Determine mitigation and enhancement initiatives within the project by working with stakeholders, local biologists and other environmental specialists.

• Implement biodiversity management and mitigation plans and assess potential outcomes to drive toward achievement of the intended objectives.

  ' International Finance Corporation's Performance Standards on Environmental and Social Sustainability include: Performance Standard 1 - Assessment and Management of Environmental and Social Risks and Impacts; Performance Standard 3 - Resource Efficiency and Pollution Prevention; Performance Standard 4 - Community Health, Safety, and Security and Performance; Performance Standard 6 - Biodiversity Conservation and Sustainable Management of Living Natural Resources.

  PRIORITY AREAS FOR NATURAL RESOURCE CONSERVATION

  • Improving air quality

  • Maintaining emergency preparedness

  • Preventing spills

  • Protecting biodiversity

  • Reducing freshwater withdrawal

  Certified

  ' To learn more about the wildlife habitat at the Galveston Bay refinery, please visit our website.

  Table of Contents Overview Advance Environmental Stewardship Empower Our People Engage Stakeholders and Communities Execute with Integrity Appendix Additional Resources 14

  Pipeline N"ture Imp"ct Mitig"tion

  Our recent efforts have prioritized identifying and assessing location-specific risks of pipeline operations in areas of threatened or endangered species habitat. Risks identified include habitat impacts, species movement and nature-related dependency risks including water quality and soil stabilization. To mitigate these risks, we apply best management practices and techniques throughout the pipeline life cycle.

  	Conservation Mowing Adjusting mowing schedules and mower height throughout the year helps protect ground-nesting birds and avoid disturbing wildlife during important migration periods.
  	Selective Herbicide Applying U.S. EPA-approved products to target invasive or incompatible plant species mitigates impacts to native vegetation. Weed management plans keep treated areas free of invasive and non-native weeds.
  	Enhanced Planting Planting seeds that attract pollinators or provide food to boost biodiversity helps crowd out incompatible or invasive plants.
  	Hand Clearing Clearing woody plants by hand and using targeted treatments help minimize disruption in the area.
  	Assessments and Education

  • Conducting post-construction surveys and research to verify sensitive areas have been appropriately restored.

  • Monitoring wetland and waterway crossing sites on pipeline rights of way to confirm they are fully restored and functioning.

  • Training employees and contractors about biodiversity and maintaining assets in sensitive areas.

  • Using signage to identify sensitive areas.

  BEST MANAGEMENT PRACTICES AND TECHNIQUES APPLIED TO MITIGATE IMPACTS TO NATURE

  STAGES OF BEST MANAGEMENT

  PRACTICES ON THE RIGHT OF WAY

  BEFORE

  Woody vegetation and other incompatible plant species require a routine maintenance schedule. The best treatment application method for the terrain and existing vegetation is determined.

  DURING

  Incompatible vegetation begins to turn brown in one to two weeks of targeted treatment. This is a sign of successful application.

  Selective treatments do not affect compatible vegetation we want to retain.

  AFTER

  After incompatible vegetation has been eliminated, a mix of native, compatible vegetation can be observed along the rights of way. While slightly less manicured, it requires less overall maintenance, supports biodiversity and improves soil stability.

  NATIVE RESTORATION ALONG THE RIGHT OF WAY IN WEST VIRGINIA

  In 2025, we restored multiple pipeline sites affected by slope failure in West Virginia using a purpose-designed seed mix tailored to support sustainable right of way vegetation management. The mix was developed to achieve rapid soil cover, meet erosion and sediment control requirements, and outcompete woody vegetation that could compromise our ability to inspect for leaks.

  The blend includes regionally appropriate grasses with dense, fibrous roots for stabilization and flowering species to support pollinators without limiting access or asset integrity.

  Avoid

  For effective vegetation management, we keep existing ground cover in place and avoid any unnecessary disturbance. This helps prevent erosion, slope failures and the spread of unwanted plants.

  Reduce

  By establishing an intentional native and regionally adapted seed mix with deep, fibrous root structures, we reduce the likelihood of future slip incidents. Dense root networks improve soil cohesion, enhance slope stability and decrease long-term vegetation maintenance needs.

  Regenerate

  Rights of way in forested landscapes are naturally prone to recolonization by woody vegetation, which is not compatible with pipeline safety and access requirements. Through targeted species selection, we regenerate disturbed areas with a native vegetation community designed to outcompete woody species.

  Restore

  Restoration activities include regrading terrain, applying suitable seed mixes and stabilizing slopes based on soil and site conditions. These actions restore disturbed areas to a stable state while ensuring the continued protection and integrity of pipeline assets.

  Conservation Agriculture Program

  MPL's Conservation Agriculture program supports pipeline integrity and responsible land stewardship along rights of way by promoting erosion control and sustainable land management practices in collaboration with farmers.

  The program prioritizes areas of shallow cover and locations where erosion could increase the potential for pipeline exposure. MPL works with farmers to identify appropriate conservation measures and implement them in a manner aligned with agricultural operations and site conditions.

  Planting native grasses and flowers can significantly reduce soil and nutrient loss from fields, helping maintain soil fertility and protecting water quality.

  These conservation measures also support habitat function and broader biodiversity and pollination outcomes while helping manage erosion risks along pipeline rights of way.

  "We can help native plants and wildlife survive and thrive by creating sustainable habitats that help improve the local environment while protecting our assets and saving money."

  Scott Sharpe

  Senior Environmental Specialist

  
  
  

  Table of Contents Overview Advance Environmental Stewardship Empower Our People Engage Stakeholders and Communities Execute with Integrity Appendix Additional Resources 15

  M"r"thon Pipe Line Sust"in"ble L"ndsc"pes Initi"tive

  Marathon Pipe Line (MPL) is harnessing the power of nature-based solutions. MPL is putting Integrated Vegetation Management (IVM)1 and Integrated Habitat Management (IHM)2 plans in place through partnerships and technology.

  Together, these practices help MPL to operate its pipelines safely while enhancing habitat for pollinators and wildlife, reducing impact to operations and promoting long-term environmental health.

  In 2023, MPL set a target to apply sustainable landscapes to approximately 10,000 acres (50%) of compatible rights of way by the end of 2025. Through collaborative efforts, the team has made consistent annual progress. MPL ended 2025 having applied 10,215 acres of sustainable landscapes across its assets, which span 26 states.

  Restoration initiatives are implemented in areas where we have direct access and operational oversight, enabling effective management and monitoring. Industrial and privately owned lands are not in scope and are addressed through stakeholder engagement where feasible.

  Achieving our initial target is simply a milestone toward our biodiversity commitment. We continue to explore opportunities to increase native landscapes and decrease invasive plants along our rights of way.

  Biodiversity - Sustainable Landscapes

  (acres)

  • 2025 Goal ● Progress

1O,215 acres

w1O,OOO

acres

Apply sustainable landscapes to w1O,OOO acres (w5O%) of compatible MPL rights of way by the end of 2025

METHOD FOR SUCCESS

We're achieving results while applying sustainable landscapes to pipeline rights of way. These results are achieved through coordination with many stakeholders to realize shared value.

Assess site conditions and set goals

Landowners and partners are engaged in the evaluation process to set goals specific to location, land use, habitats, species and other criteria.

Develop implementation plans

Plans consider site-specific goals to promote native species, increase pollinator plants, promote water quality and soil stabilization, and connect fragmented habitats. Plans prioritize pollinator and grassland habitats that provide critical habitats for threatened and endangered species.

Implement restoration activities

Plans are executed in conjunction with contractors and partners and documented through mapping tools and technology that help track progress and support desired outcomes.

Monitor progress

Sites are monitored to assess progress toward intended objectives.

Evaluate outcomes

Success is evaluated by verifying all objectives and criteria have been met within our executed plan.

To sustain progress creating sustainable landscapes, MPL engages the following partner organizations:

• The Ohio State University School of Environment and Natural Resources (SENR) to conduct research on pipeline rights of way with a focus on ecology, soil carbon and landowner relations.

• Penn State College of Agricultural Sciences to conduct research on the restoration of landscape along a right of way in Pennsylvania through a naturally occurring seed bank, without external seeding.

• Mule Deer Foundation to evaluate habitat impacts in western states near our assets.

  N"tionwide Conserv"tion Agreement for the Mon"rch Butterfly

  MPLX proudly signed the Nationwide Candidate Conservation Agreement with Assurances (CCAA) for Monarch Butterflies on Energy and Transportation Lands, a unique collaboration between academia, regulators and industry. This agreement underscores our commitment to enhancing biodiversity and supporting monarch butterfly populations. We achieve this by enhancing our rights of way to promote the growth of milkweed and nectar resources.

  5,7OO+

  vegetation assessments completed by MPL since 2O22

  1 Integrated Vegetation Management (IVM): A flexible, adaptive process of managing plant communities using a variety of methods to promote and protect compatible vegetation while aligning with the intended purpose of the land.

  2 Integrated Habitat Management (IHM): A process that adheres to IVM principles with the added intention to improve habitat by promoting biodiversity, connecting wildlife corridors to address habitat fragmentation and providing habitat for migratory insects, birds and various wildlife species.

  
  
  

  Table of Contents Overview Advance Environmental Stewardship Empower Our People Engage Stakeholders and Communities Execute with Integrity Appendix Additional Resources 16

  Water

  We actively monitor water efficiency and utilization throughout all operations, continually looking for ways to reduce our reliance on this shared resource and mitigate risks effectively.

  In 2025, through collaborative efforts and enhanced emphasis on water savings opportunities, we achieved our companywide target to reduce freshwater withdrawal intensity by 20% from 2016 levels. This was accomplished five years earlier than our initial goal attainment date. This equates to approximately 2 billion gallons of fresh water saved annually since 2016.

  W"ter Use in Oper"tions

  Water is vital to our operations. Depending on the location, we may source water from rivers, lakes, wells, municipal water systems and, in some cases, recycled sources. The majority of our companywide water demand comes from refining operations. In contrast, MPLX natural gas processing plants are designed to use little or no water in their routine operations. Nearly all natural gas processing plants use air-cooling systems that circulate hot product through air-cooled radiators, minimizing the need for water.

  Uses in MPC

• Add heat to refining process (as steam)

• Clean equipment during maintenance activities

• Control emissions

• Generate hydrogen

• Protect equipment from corrosion

• Purify products (as stripping steam)

• Remove heat from the process (as cooling water)

• Remove salts and impurities from crude oil

  Uses in MPLX

• Clean equipment during maintenance activities

• Create emulsions (asphalt blending)

• Install pipelines (horizontal directional drilling)

  1OO

  9O

  8O

  Freshwater Withdrawal Intensity

  (megaliters/million boe input)

  • 2030 Goal ● Progress

    2O%

    2O%

    2O% reduction of freshwater withdrawal intensity by 2030 from 2016 levels

    Freshwater Withdrawal Intensity

    (megaliters/million boe input)

    93

    8O

    WATER MANAGEMENT ACTIONS

    Improved capture and reuse of wastewater to reduce freshwater demand

    Enhanced wastewater treatment technologies, including reverse osmosis systems

    Optimized water use through operational control system improvements

    Reduced steam and water demand through steam management initiatives and equipment upgrades

    M"n"ging W"stew"ter

    We operate 11 biological treatment plants and four primary treatment facilities across our refineries and renewable fuels facilities. Water not reused or consumed is collected at these on-site facilities where it is either treated and recycled back into manufacturing processes, treated and discharged in accordance with applicable requirements, or treated and sent to a publicly owned treatment works. Water is treated

• Heat asphalt tanks (as steam)

• Remove impurities from natural gas

• Test pipeline and tank integrity (hydrostatic testing) 7O

  77 76 76

  74

  2O16 2O21 2O22 2O23 2O24 2O25

  2O% REDUCTION GOAL BY 2030

  to meet or exceed permit effluent limits before it is discharged to surface waters such as lakes, rivers and bays, helping to protect the quality of the water. Extensive monitoring, sampling, operator rounds and equipment surveillance are conducted to ensure that water discharges remain within permitted effluent limits.

  
  
  

  Table of Contents Overview Advance Environmental Stewardship Empower Our People Engage Stakeholders and Communities Execute with Integrity Appendix Additional Resources 17

  Loc"l W"ter Conserv"tion

  Water availability is a growing concern in many regions around the world, including parts of the U.S. Currently, three of MPC's operating refineries - El Paso, Texas; Salt Lake City, Utah; and Los Angeles, California - plus one renewable fuels facility - Martinez, California - are located in medium to high water-stressed regions as defined by the Global Reporting Initiative (GRI) and World Resources Institute assessment tools. To help conserve water in these regions, as well as at other MPC refineries, our refining teams tailor site-specific plans using aspects of a nine-element management framework. The framework is designed to assess water use, identify and mitigate water risks, and uncover opportunities to reduce water use.

  Each MPC refinery has designated engineers who serve as water coordinators, have defined baselines for assessing water use and maintain clear and consistent transparency with site leadership on how water is used through structured water monitoring and reporting.

  To help manage and mitigate local water risks, we engage community members, government agencies and key water supply organizations. These engagements help us track and monitor the local water supply and plan for future changes in water quality, availability, accessibility, pricing and regulation. We support water supply organizations through membership, board leadership and committee participation.

  Water supply organizations we engage with:

• American Petroleum Institute's Clean Water Issues Group

• Brazos River Authority (Texas)

• California Council for Environmental and Economic Balance

• Far West Texas Water Planning Group

• Gulf Coast Water Authority (Texas)

• New Mexico Produced Water Research Consortium

• Utah Petroleum Association Water Work Group

• West Basin Water Association (California)

73%

of fresh water withdrawn from nonwater-stressed areas1

1 World Resources Institute Aqueduct Water Risk Atlas

OUR WATER MANAGEMENT FRAMEWORK

1

Water Limits

Actual water usage and discharges are tracked against known limits.

1. Accounting

   Water monitoring programs integrate

   contractual water volume and cost.

   Value Chain and Community Engagement

2. Mutually beneficial opportunities are sought

   to reduce water demands, costs and reliance on single-water sources.

   Impacts

3. Water-related business and compliance issues are tracked, investigated and mitigated.

   Risks

4. Water-related risks are identified and

   assessed based on impact to the company and community.

5. Targets and Goals

Water targets and goals are set.

7

Opportunities

Opportunities are identified and applied to meet water targets and goals and improve performance relative to benchmarking.

8

Monitoring and Performance

Water withdrawals are measured to benchmark water demands and understand consumption.

9

Commitment and Engagement Expectations of water targets and goals are clearly communicated, and resources for successful implementation are assigned.

Through a variety of innovations guided by our formal Focus on Water program, we continue to make strides improving the efficiency of our freshwater use and reducing our freshwater withdrawal intensity. In addition to achieving our freshwater withdrawal intensity target five

years early, we continue to monitor freshwater performance metrics and implement efficiency initiatives to sustain performance and effectively manage water-related risks.

2O25 MPLX Water Savings

To minimize operational disruption and conserve resources, MPLX teams are utilizing Fitness-for-Service (FFS) assessments in lieu of hydrostatic testing, where appropriate. This approach leverages advanced engineering analysis to verify tank integrity while conserving water and reducing operational downtime.

Following a positive evaluation, an FFS certificate is issued and clearly defines any conditions such as operating limits and follow-up requirements.

2O25 REFINING PROJECTS TO REDUCE FRESHWATER WITHDRAWAL

Detroit, Michigan, refinery

w62 million gallons projected annual savings through ongoing optimization of the reverse osmosis unit by raising the unit's outlet pressure limit. The unit treats wastewater effluent for reuse, reducing the city water demand.

Salt Lake City, Utah, refinery

w27 million gallons projected annual savings through water softener optimization and increasing condensate return.

Garyville, Louisiana, refinery

w62 million gallons projected annual savings from a procedural change resulting in increased duration between softener regeneration cycles and decreased flow rates.

MPLX Natural Gas and NGL Services saved

4.7 million+

gallons of fresh water through systematic conservation efforts, including the return of used, uncontaminated hydrostatic test water to local water depots or to the environment.

Additional savings were identified on softeners through improved testing practices.

Galveston Bay, Texas, refinery

w556 million gallons projected annual savings by sending reverse-osmosis wastewater back to the influent water treatment plant, routing filtered backwash to the clarifier for reuse instead of going to the sewer and by installing a new resin, allowing for a reduced number of regeneration cycles on the demineralizer treatment units.

Robinson, Illinois, refinery

MPLX Crude Oil and Products Logistics saved

18 million+

gallons of fresh water by continuing to replace hydrostatic tests on storage tanks with the use of phased-array ultrasonic testing, X-ray inspections, magnetic particle examination and volumetric weld testing.

w36 million gallons projected annual savings by increasing the reverse osmosis unit recovery rate and conducting steam leak repairs.

Los Angeles, California, refinery

w52 million gallons projected annual savings by increasing flow to the condensate recovery tank of a hydrogen generation unit as a result of improved process control strategies.

w135 million gallons projected annual savings through well repairs and installation of a section of pipe that allows for the use of well water instead of city water.

Table of Contents Overview Advance Environmental Stewardship Empower Our People Engage Stakeholders and Communities Execute with Integrity Appendix Additional Resources 18

Zero is always our goal.

Safe and reliable operations are at the core of how we protect communities, safeguard the environment and sustain long-term value for our business. We support this commitment through disciplined operational practices, a comprehensive pipeline integrity management program and advanced monitoring and inspection technologies.

In 2025, 99.9999% of all volumes transported via MPL-operated pipelines were delivered without a spill incident, reflecting the effectiveness of our prevention-focused approach and continuous investment in pipeline safety.

Our extensive Integrity Management program seeks to identify and respond to integrity threats to our pipeline systems. This program's aim is to protect all areas from spills. We prioritize areas where a spill from a pipeline could affect a densely populated area, drinking water, ecologically sensitive zones or a commercially navigable waterway. Through annual risk modeling, we systematically identify potential hazards to each pipeline and assess their relative significance, allowing us to develop effective mitigation measures. These risks may include damage by third parties, corrosion, cracks, dents, operator error, manufacturing defects, equipment failure, geohazards or weather events.

PIPELINE INTEGRITY MANAGEMENT

Design and Construction

We apply rigorous inspection and quality-control procedures throughout pipeline design and construction. These include route and material selection, welding, testing and site restoration, and supporting safe and reliable operation throughout the asset life cycle.

Preventive Maintenance

Our pipelines and associated equipment undergo recurring inspection, testing and preventive maintenance to verify sound integrity and proper function. When warranted, we complete repairs and implement additional mitigation measures to proactively manage risk.

Corrosion Control

Coatings are applied to the outer surface of pipelines, and cathodic protection systems are installed along pipeline routes to help prevent external corrosion. Full cathodic protection inspections are conducted annually to verify that these systems are functioning properly. Internal corrosion is managed through the use of maintenance tools and, where appropriate, anticorrosive chemical injections to protect pipeline integrity.

Inspections1

We use multiple, complementary inspection methods to assess pipeline condition and identify potential integrity concerns:

• Above-ground inspections: Aerial and ground patrols identify third-party activity, land disturbance and signs of release. Liquid pipelines are inspected at least every three weeks, and gas transmission pipelines at least annually.

• Navigable waterway crossing inspections: High-resolution sonar equipment is used to assess erosion and channel movement at water crossings at least once every five years for both liquid and gas transmission pipelines.

• In-line inspections: Advanced inspection tools travel through pipelines to measure pipe walls and detect dents, corrosion, cracking and other anomalies. Liquid transmission pipelines are inspected at least once every five years and gas transmission pipelines at least once every seven years.

Pipeline Safety Management

We educate landowners, first responders and community partners located near our pipelines about safe digging practices and emergency response.

' Learn more about the Earning Your Trust program in the Connecting with Communities section on Page 34.

Geohazard Management

Our geohazard management program monitors, assesses and remediates risks associated with earth movement, including landslides and subsidence in varied terrain and geological conditions. The program includes employee training, periodic assessments and targeted mitigation actions grounded in industry best practices.

These efforts also support environmental protection through the application of sustainable landscapes along pipeline rights of way to reduce soil erosion and enhance subsurface stability.

' Learn more about our work applying sustainable landscapes to pipeline rights of way in our Sustainable Landscapes section on Page 15.

Monitoring and Detection

Pipeline pressure, flow and volume are monitored 24/7 by trained personnel. Sensors and metering systems detect abnormal conditions, such as changes in pressure or flow rate, and alert control center staff to support prompt investigation and response.

1 MPC and MPLX conform to inspection frequency requirements contained in 49 CFR 195 and 192. Listed inspection frequencies apply to regulated pipelines only.

Advancing In-Line Inspection

In 2025, we strengthened our in-line inspection (ILI) program by partnering with vendors on two issues - axial strain and pipeline metal loss. Axial strain is the longitudinal movement that pushes or pulls along the length of a pipe. Axial strain tools were evaluated through baseline and repeat inspections with field validation at areas of known or suspected ground movement. These tools improved detection of geohazard-related loading, such as landslides, and assessment of pipe response to external forces. To address pipeline metal loss, we applied high-resolution Magnetic Flux Leakage (MFL) technologies within pipeline integrity evaluations, upgraded with increased sensor density. This upgrade enhanced anomaly detection and sizing accuracy and reduced uncertainty in integrity evaluations.

We also collaborated with an ILI vendor to present and publish a technical paper at the Pipeline Pigging and Integrity Management Conference, sharing lessons learned to support broader industry advancement.

Table of Contents Overview Advance Environmental Stewardship Empower Our People Engage Stakeholders and Communities Execute with Integrity Appendix Additional Resources 19

Adv6nced Monitoring 6nd Right-of-W6y Inspection

We strengthen spill prevention and preparedness strategies through ongoing investment in advanced technologies that improve asset integrity, reduce incident risk and enhance response readiness across our operations.

We continue to expand the use of Flyscan, an artificial intelligence (AI)-driven right-of-way threat and leak detection technology that scans pipeline corridors from patrol aircraft with greater sensitivity and accuracy than traditional visual inspections. Our collaboration with Flyscan Systems Inc. continues to advance the capabilities of the technology and improve inspection practices across the pipeline industry.

AI-En6bled Le6k Detection 6nd F6cility Monitoring

AI-enabled cameras support real-time monitoring at 172 of our remote pipeline facilities, with enhanced leak and threat detection functionality active at 129 locations.

Traditional camera monitoring relies on human review or object-detection models that could miss subtle conditions.

To enhance detection sensitivity and accelerate response times, we developed an internal, camera-based leak detection model using AI Vision Language Models.

Applied to existing video feeds, this technology interprets visual conditions, identifies abnormal patterns and detects potential liquid leaks and other anomalies within approximately 30 seconds. Following a successful pilot in 2025, this model continues to evolve, supporting faster detection, improved decision-making and enhanced pipeline safety.

In 2025, we further advanced these capabilities at 20 Los Angeles-area pipeline vault sites, which provide access to critical underground pipeline infrastructure. By deploying DirectC technology and implementing customized algorithms tailored to individual pipeline segments, we enabled faster response, earlier leak identification and reduced release volumes.

MARINE INTEGRITY MANAGEMENT

Our marine operations include Global Marine and Inland Marine environments, each presenting unique challenges. To address these challenges and minimize impacts to the public, wildlife and the environment, we deploy a comprehensive vessel vetting, inspection and compliance program for all vessels1 we own, operate or charter.

As a member of the Oil Companies International Marine Forum (OCIMF) - and with representation on its executive board - we actively promote the safe and environmentally responsible transportation of oil and gas by water. Through leadership and participation in OCIMF committees, we contribute to the development of industry best practices that help inform International Maritime Organization (IMO) regulations and global Port State Control regimes, including oversight by the U.S. Coast Guard.

Insights from this engagement also support the continuous enhancement of our marine integrity management practices.

Vetting and Inspection Programs

Our commitment to marine safety is reflected in rigorous vessel vetting and inspection requirements designed to help identify and address risks before they result in safety or environmental impacts. Key elements of our approach include:

• Comprehensive vessel screening against 43 regulatory and compliance sources, including U.S. Office of Foreign Assets Control sanctions and international regulatory watch lists such as the Paris Memorandum of Understanding blacklist.

• Strict eligibility criteria, under which vessels with poor inspection histories, unacceptable flag state performance or active sanctions are not permitted to conduct business with MPC.

• Use of OCIMF inspection programs - including the Ship Inspection Report and Barge Inspection Report - as a baseline for evaluating vessels we own, operate or charter, as well as vessels calling at third-party terminals where we hold tankage.

Port State Control Compliance

These vetting and industry inspection programs are complemented by Port State Control (PSC) oversight. Every vessel we own, operate or charter is subject to PSC inspections to verify compliance with applicable international, federal and local regulations. These inspections assess vessel condition, equipment integrity, crew qualifications and operational practices to confirm adherence to safety and environmental requirements.

1 Includes tankers, bulk carriers, gas tankers, tugs, barges and articulated tug and barges.

Port of Long Beach

GREEN FLAG AWARD

Marathon Petroleum earned the 2O24 Port of Long Beach Green Flag Award in recognition of its continued participation in a voluntary vessel speed reduction program that reduces smog-forming emissions and diesel particulates near the port, supporting improved air quality and community well-being.

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Meticulous planning and strategic preparedness are critical to responding effectively in the event of an emergency. Our comprehensive emergency preparedness and response program is designed to safeguard people, protect the environment and maintain safe, reliable operations.

Through continuous improvement, training and investment in response capabilities, we work to minimize and mitigate potential impacts to our operations, communities and customers.

MPC's Emergency Preparedness Group (EPG), in partnership with emergency preparedness professionals within each operating component, oversees the companywide emergency response program. The program focuses on continuously strengthening our ability to respond swiftly and effectively to emergency situations at any of our facilities or operating areas.

The EPG develops and maintains procedures and guidelines for managing emergency situations, while sharing resources and best practices with other business units. To support the effectiveness of our plans and alignment with regulatory expectations, the EPG coordinates routine evaluations of our response plans with regulatory agencies, including the U.S. EPA, the U.S. Coast Guard, the Pipeline and Hazardous Materials Safety Administration (PHMSA) and appropriate state agencies.

Each of our operational sites maintain site-specific emergency preparedness and response plans to address the distinct risks of each location, and receive additional support from local and/or regional emergency response teams. We conduct regular drills and exercises to ensure that our teams are equipped to respond with precision and confidence, should an incident occur.

For incidents larger in scope and complexity that exceed the resources available at a local facility, we activate support from Marathon's Corporate Emergency Response Team (CERT). Comprised of more than 230 trained employees, CERT provides specialized expertise, corporate manpower and coordinated response management to support major emergencies. The team is maintained to ensure that corporate resources, operational support and response leadership are readily available. Each CERT member is highly trained and certified in the Incident Command System - a globally recognized framework for coordinating resources across multiple agencies and organizations.

EMERGENCY PREPAREDNESS EXERCISES

CERT members and other emergency response personnel participate in a wide range of training exercises to maintain a high level of readiness. These efforts include collaboration with federal, state, local and tribal responders - such as the U.S. EPA, the U.S. Coast Guard, state environmental protection or wildlife agencies, tribal government representatives and local emergency responders. In addition, MPC and MPLX maintain a robust response simulation program designed to test and continuously enhance our response capabilities.

• Our exercises follow the guidelines of the federal government's National Preparedness for Response Exercise Program (PREP), ensuring compliance with the Oil Pollution Act of 1990 as well as all federal, state and local requirements.

• Exercises are designed to prepare for various emergency situations and to thoroughly review, critique and improve our emergency response plans.

• We take a collaborative approach to emergency preparedness. In addition to training our own employees and contractors, we actively engage federal, state, local and tribal agencies, local fire departments, law enforcement and other first responders and community leaders who have a vested interest in the design and development of our plans and exercises.

  CERT Resources "nd Support

  We maintain a structured incident response framework composed of specialized teams that provide operational, executive and functional support across a broad spectrum of emergency scenarios.

• Emergency Strike Te6m: A stand-alone response management team capable of supporting, supplementing or relieving roles in a major emergency.

• Emergency Support Group: Provides key support functions, such as IT, communications and geographic information system mapping during an incident.

• Crisis M6n6gement Te6m: Provides executive-level leadership response to MPC's and MPLX's needs during significant incidents.

• Business Recovery Te6m: Works to meet MPC's, MPLX's and customers' needs during supply disruptions.

• Thre6t Assessment Group: Evaluates the potential impact of a threat to MPC or MPLX, informs impacted stakeholders and recommends steps to protect people and assets.

• Intern6tion6l Te6m: Determines potential impacts, recommends response strategies and responds to incidents related to the shipment of crude oil and refined products outside the United States.

MPC and MPLX use a tiered response system that enables incidents to be managed at the local, regional or corporate level as needed.

In 2025, MPC conducted a three-day multistate CERT exercise in Huntington, West Virginia, with approximately 225 participants. Participants included employees, support contractors and representatives from more than 20 federal, state and local agencies, who collectively managed a complex emergency scenario under a Unified Command structure.

Employees collaborated in real time across planning, operations, logistics, finance and public information functions. The exercise reinforced coordinated decision-making, effective public communication and the importance of strong partnerships with community stakeholders.

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"lt's really important that we practice these scenarios, specifically this one with the community, because it's so core to who Marat on is as a guardian of pu lic safety, protecting the environment and bei g engaged in our communities."

Aron Velasquez

Right of Way & Public Engagement Manager

In addition to strengthening our emergency response capabilities, we continue to enhance our business continuity and resiliency plans across operations to ensure we can meet supply commitments during and after an emergency.

Designated business continuity coordinators are embedded across the organization to maintain alignment, support informed decision-making and help ensure our energy products continue to reach markets during challenging conditions.