Three Rivers WaterKeeper to Sue US Steel Over Monongahela River Oil Discharges

Environmental group alleges repeated violations of Pennsylvania Clean Streams Law at Irvin Works Plant

Published on Feb. 11, 2026

Got story updates? Submit your updates here. ›

The Three Rivers WaterKeeper has announced plans to sue U.S. Steel over repeated oil discharges from its Irvin Works Plant that have created an oily sheen on the Monongahela River. The group says the discharges violate Pennsylvania's Clean Streams Law, despite a recent consent order requiring U.S. Steel to address the issue.

Why it matters

The Monongahela River is a vital waterway that provides drinking water for millions of people across the Ohio River Basin. Persistent oil discharges threaten the river's ecosystem and raise concerns about the effectiveness of environmental regulations and enforcement actions against major industrial polluters.

The details

The Three Rivers WaterKeeper, represented by Appalachian Mountain Advocates, has sent a formal notice of intent to sue U.S. Steel over the oil discharges. The group says it has observed oil sheens ranging from 2 to 18 miles long on the river, some lasting for days. In November 2025, the Pennsylvania Department of Environmental Protection reached a consent order with U.S. Steel requiring the company to pay $135,000 in fines and take steps to monitor and eliminate the petrochemical sheens. However, the WaterKeeper says it has documented additional sheen events on the river since the consent order was signed.

  • On February 10, 2026, the Three Rivers WaterKeeper announced plans to sue U.S. Steel.
  • On November 20, 2025, the Pennsylvania DEP entered a consent order with U.S. Steel to address the oil discharges.
  • The WaterKeeper says it has observed oil sheens on the Monongahela River on at least 4 days in December 2025 and January 2026, after the consent order was signed.

The players

Three Rivers WaterKeeper

An environmental group that protects the Allegheny, Monongahela, and upper Ohio Rivers, which make up the headwaters of the Ohio River Basin.

U.S. Steel

A major steel manufacturer with an Irvin Works Plant located in West Mifflin, Pennsylvania that has been the source of repeated oil discharges into the Monongahela River.

Pennsylvania Department of Environmental Protection

The state environmental agency that entered into a consent order with U.S. Steel in November 2025 to address the oil discharges.

Appalachian Mountain Advocates

The law firm representing the Three Rivers WaterKeeper in its planned lawsuit against U.S. Steel.

Evan Clark

Captain of the Three Rivers WaterKeeper.

Heather Hulton VanTassel

Executive Director of the Three Rivers WaterKeeper.

Got photos? Submit your photos here. ›

What they’re saying

“Can we move beyond the bad old days of our rivers covered in oil in Pittsburgh? U.S. Steel has long been aware of this persistent problem and not corrected the issues that have caused our communities and our rivers to suffer. The fines they've received don't go nearly far enough towards addressing more than a decade of past neglect or making it financially unattractive to continue with business as usual.”

— Evan Clark, Captain, Three Rivers WaterKeeper (blogspot.com)

“Pennsylvania's Clean Streams Law and the accompanying regulations are clear: discharges that create a sheen on our rivers are illegal. Full stop.”

— Heather Hulton VanTassel, Executive Director, Three Rivers WaterKeeper (blogspot.com)

“Decades of research has shown that a visible sheen is a telltale sign that oil discharges are harming the aquatic ecosystem.”

— Heather Hulton VanTassel, Executive Director, Three Rivers WaterKeeper (blogspot.com)

What’s next

The judge will decide whether to allow the Three Rivers WaterKeeper's lawsuit against U.S. Steel to proceed.

The takeaway

This case highlights the ongoing challenges of holding major industrial polluters accountable, even in the face of clear environmental regulations. The Three Rivers WaterKeeper's lawsuit aims to force U.S. Steel to finally address its long-standing pollution issues and protect the vital Monongahela River ecosystem.