Item 4. Controls and Procedures

Disclosure Controls and Procedures

An evaluation of the effectiveness of the design and operation of our disclosure controls and procedures (as defined in Rule 13a-15(e) under the Securities Exchange Act of 1934, as amended) was carried out under the supervision and with the participation of our management, including our chief executive officer and chief financial officer. Based upon that evaluation, the chief executive officer and chief financial officer concluded that the design and operation of these disclosure controls and procedures were effective as of September 30, 2023, the end of the period covered by this report.

Changes in Internal Control over Financial Reporting

During the quarter ended September 30, 2023, there were no changes in our internal control over financial reporting that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

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PART II – OTHER INFORMATION

Item 1. Legal Proceedings

We are the subject of, or a party to, a number of pending or threatened legal actions, contingencies and commitments involving a variety of matters, including laws and regulations relating to the environment. While it is possible that an adverse result in one or more of the lawsuits or proceedings in which we are a defendant could be material to us, based upon current information and our experience as a defendant in other matters, we believe that these lawsuits and proceedings, individually or in the aggregate, will not have a material adverse effect on our consolidated results of operations, financial position or cash flows.

Item 103 of Regulation S-K promulgated by the SEC requires disclosure of certain environmental matters when a governmental authority is a party to the proceedings and such proceedings involve potential monetary sanctions, unless we reasonably believe that the matter will result in no monetary sanctions, or in monetary sanctions, exclusive of interest and costs, of less than a specified threshold of $1 million for this purpose.

Except as described below, there have been no material changes to the legal matters previously disclosed in our Annual Report on Form 10-K for the year ended December 31, 2022, or in our Quarterly Report on Form 10-Q for the quarter ended March 31, 2023 or for the quarter ended June 30, 2023.

Dakota Access Pipeline

As reported in our Annual Report on Form 10-K for the year ended December 31, 2022, MPLX holds a 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL. In 2020, the U.S. District Court for the District of Columbia (the “D.D.C.”) ordered the U.S. Army Corps of Engineers (“Army Corps”), which granted permits and an easement for the Bakken Pipeline system, to prepare an environmental impact statement (“EIS”) relating to an easement under Lake Oahe in North Dakota. The D.D.C. later vacated the easement. The Army Corps issued a draft EIS in September 2023 detailing various options for the easement going forward, including denying the easement, approving the easement with additional measures, rerouting the easement, or approving the easement with no changes. The Army Corps has not selected a preferred alternative, but will make a decision in its final review, after considering input from the public and other agencies. The Army Corps has not provided a definitive date as to when a final decision would be issued.

In May 2021, the D.D.C. denied a renewed request for an injunction to shut down the pipeline while the EIS is being prepared. In June 2021, the D.D.C. issued an order dismissing without prejudice the tribes’ claims against the Dakota Access Pipeline. The litigation could be reopened or new litigation challenging the EIS, once completed, could be filed. The pipeline remains operational.

MPLX has entered into a Contingent Equity Contribution Agreement whereby it, along with the other joint venture owners in the Bakken Pipeline system, has agreed to make equity contributions to the joint venture upon certain events occurring to allow the entities that own and operate the Bakken Pipeline system to satisfy their senior note payment obligations. The senior notes were issued to repay amounts owed by the pipeline companies to fund the cost of construction of the Bakken Pipeline system. If the vacatur of the easement results in temporary shutdown of the pipeline, MPLX would have to contribute its 9.19 percent pro rata share of funds required to pay interest accruing on the notes and any portion of the principal that matures while the pipeline is shutdown. MPLX also expects to contribute its 9.19 percent pro rata share of any costs to remediate any deficiencies to reinstate the easement and/or return the pipeline into operation. If the vacatur of the easement results in a permanent shutdown of the pipeline, MPLX would have to contribute its 9.19 percent pro rata share of the cost to redeem the bonds (including the 1 percent redemption premium required pursuant to the indenture governing the notes) and any accrued and unpaid interest. As of September 30, 2023, our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement were approximately $170 million.

Martinez Refinery

On October 20, 2023, Tesoro Refining & Marketing Company LLC, an indirect wholly owned subsidiary of MPC, received an offer to settle 59 Notices of Violation (“NOVs”) received from the Bay Area Air Quality Management District. The NOVs were issued for alleged violations of air quality regulations at our Martinez refinery between June 2018 and May 2022. We cannot currently estimate the timing of the resolution of this matter but do not believe any civil penalty will have a material impact on our consolidated results of operations, financial position or cash flows.

Edwardsville Incident

As reported in our Annual Report on Form 10-K for the year ended December 31, 2022, in March 2022, the State of Illinois brought an action in Madison County Circuit Court in Illinois against Marathon Pipe Line LLC (“MPL”), an indirect wholly owned subsidiary of MPLX, asserting various violations and demanding a permanent injunction and civil penalties in connection with a release of crude oil on the Wood River to Patoka 22" line near Edwardsville, Illinois in March 2022. In September 2023, the U.S. Department of Justice and EPA confirmed they will be pursuing federal enforcement for alleged Clean Water Act violations arising from this incident as well as other pipeline releases. We cannot currently estimate the amount of any civil penalty or the

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timing of the resolution of this matter but do not believe any civil penalty will have a material impact on our consolidated results of operations, financial position or cash flows.