MPLX LP

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.

See “Tesoro High Plains Pipeline” and “Dakota Access Pipeline” of Note 22 in Item 8. Financial Statements and Supplementary Data for additional information regarding Legal Proceedings and other regulatory matters.

ENVIRONMENTAL ENFORCEMENT MATTERS

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. We use a threshold of $1 million for this purpose.

In March 2022, the State of Illinois brought an action in Madison County Circuit Court in Illinois against Marathon Pipe Line LLC, 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-inch line near Edwardsville, Illinois. In September 2023, the U.S. Department of Justice and the EPA confirmed they will be pursuing federal enforcement for alleged Clean Water Act violations arising from this incident as well as three pipeline incidents in Illinois and Indiana in 2018, 2020 and 2021. 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.

On August 29, 2025, MPLX acquired Northwind Delaware Holdings LLC (“Northwind Midstream”), including its subsidiary Northwind Midstream Partners LLC, which owns and operates a sour gas treating facility in Lea County, New Mexico. We have disclosed to the New Mexico Environment Department (“NMED”) excess air emissions from the facility flares. We initiated discussions with NMED to resolve this matter and have entered into a new owner audit agreement with NMED as a result of those discussions. We do not believe any civil penalty will have a material impact on our consolidated results of operations, financial position or cash flows.