MPLX's Twelve FERC Carriers Show Ozark Rate Win, THPP Standoff
MPLX's oil-pipeline subsidiaries closed out 2024 with a court victory on Ozark's market-based rates and an unresolved tribal-land dispute still idling part of the Tesoro High Plains system.
MPLX LP (MPLX) filed twelve separate FERC Form 6 reports for 2024 covering its oil-pipeline carriers, a roster that spans legacy Marathon, Andeavor, and MarkWest-branded entities organized mostly under Delaware law, with Western Refining Pipeline, LLC (NM) the lone exception under New Mexico statute. The bulk of that group generated little regulatory activity during the year. Nine of the twelve subsidiaries reported no important changes, no rate matters, and no material financial statement notes, leaving the year's substantive disclosures concentrated in two carriers: MPLX Ozark Pipe Line LLC and Tesoro High Plains Pipeline Company LLC (ND).
On the rate front, Ozark closed out a multi-year fight over its market-based rate authority. On June 21, 2024, the D.C. Circuit denied Joint Protestants' petitions for review, upholding the authority FERC had granted the pipeline in its 2022 Opinion No. 578. The ruling removed the last appellate challenge to Ozark's pricing freedom just as a related shipper complaint reached its own resolution: the complaint against Ozark's uncommitted rates, filed under FERC Docket No. OR22-7-000, was withdrawn in June 2024 after the parties resolved all claims, closing the docket.
The two outcomes together clear Ozark's regulatory calendar for the near term. With the appellate challenge denied and the shipper complaint withdrawn in the same month, the pipeline enters 2025 without an open rate proceeding, a contrast with the unresolved dispute still weighing on THPP.
THPP's situation carries a different character entirely. The pipeline remains shut on the segment crossing the Fort Berthold Reservation amid a Bureau of Indian Affairs trespass dispute that has already produced a $187 million trespass-damages assessment and a $4 million payment from the carrier. THPP continues to challenge the BIA's March 2021 vacatur order, and litigation continues after the D.C. district court severed the government's counterclaims from the underlying case. The carrier has not restored service to the affected crossing and continues to operate around the idled portion, with no timeline disclosed for resolution.
Across the wider group, the absence of reported rate matters or financial statement notes at nine of the twelve subsidiaries points to a quiet operating year for most of the portfolio's smaller carriers, a pattern consistent with mature systems generating steady transportation revenue without new tariff filings or shipper disputes. That leaves Ozark and THPP as the two names driving the substantive news out of MPLX's FERC-regulated oil-pipeline book for 2024.
The forward path for the two active dockets diverges sharply. Ozark's market-based rate authority now stands settled at the appellate level, with the underlying shipper complaint also resolved, giving the pipeline a clean rate posture heading into 2025. THPP's outcome remains open: the carrier's challenge to the BIA vacatur order continues in litigation following the severance of the government's counterclaims, and the disputed segment remains out of service pending that resolution. MPLX's broader oil-pipeline group, spanning the Marathon, Andeavor, and MarkWest legacy names, otherwise enters the new year without disclosed rate matters requiring near-term action.