(CN) Montana rivers and waterways are in store for toxic algae blooms thanks to the Trump administration’s rollback on water-quality standards, according to an environmental group’s federal lawsuit filed on Tuesday.

In February, the U.S. Environmental Protection Agency approved what the Upper Missouri Waterkeeper organization calls in their complaint a “Poison Pill” variance that does not comply with the federal Clean Water Act.

The nonprofit environmental advocacy group argues the new variance sidesteps science-based, nutrient water-quality standards that are in place to protect Montana waters.

Nutrient pollution arrives in waterways from various sources, including factory farm runoff, sewage plants, and agricultural and urban runoff.

In 2016, the Upper Missouri Waterkeeper sued the EPA over its unscientific practice of measuring pollution in waterways. In July 2019, a federal judge agreed that the EPA could not guarantee any compliance with science-based criteria in its nutrient variances.

The court ordered the Montana Department of Environmental Quality to provide the federal agency with revised rules that were in line with recommendations made by the Waterkeeper group.

The state of Montana submitted those revised rules but the EPA balked at the revisions and instead approved several updates that cancelled out the state’s existing science-based water-quality criteria, the Upper Missouri Waterkeeper says in their complaint.

The nonprofit group dubbed these provisions a “Poison Pill” as it would undo important science-based checks from the pollution permitting process.

“EPA’s approval of the Poison Pill cites to no new evidence or record of support for its action,” the group states in its 16-page complaint. It says that, with the new nutrient standards, algae, bacterial and plant growth will sap out oxygen from waterways and kill fish and other wildlife.

“This can create toxic conditions for wildlife and humans, and causes severe habitat and aesthetic degradation in affected waters,” the complaint states.

The Upper Missouri Waterkeeper seeks oversight from the U.S. District Court for Montana under the Administrative Procedure Act.

The group calls the EPA’s approval of the poison pill variance “contrary to the evidence and arbitrary and capricious” and contends it violates existing water-quality standard laws.

In a February 24, 2020 letter announcing its decision an EPA administrator wrote that the agency’s action is “based on the more prescriptive language in the court’s various orders” and that it disapproved the Montana Department of Environmental Quality’s revisions to the nutrient variance for mechanical plants and lagoons because the revisions do not comply with the Clean Water Act “as interpreted by the district court’s orders.”

The EPA argues the district court’s orders require a reasonable timeline that “begins with the relaxed criteria of the Current Variance Standard and leads to compliance” with Montana’s water-quality standards.

The Upper Missouri Waterkeeper group is represented by Jenny Harbine from Earthjustice.

The EPA did not immediately respond to a request for comment on the allegations made in the complaint.

More From Missoula Current