BILLINGS, Mont. (AP) — The U.S. Environmental Protection Agency waded into a long-running skirmish between two states by approving water quality rules meant to protect southeastern Montana cropland from wastewater produced during natural gas drilling in neighboring Wyoming.
Wyoming officials and oil and gas companies have assailed the rules as a threat to energy production. The rules set standards that limit how much salty water — a byproduct of drilling — can enter waterways in the Tongue and Powder River basins along the Montana-Wyoming border.
Gas production in the region has declined dramatically in recent years due to falling prices. But Montana rancher Mark Fix said Thursday that he continues to see evidence of high salt levels in the Tongue River during the annual spring runoff because of past drilling. That has forced him to alter how he irrigates his fields.
Some farmers have said their crop yields dropped by more than half due to poor-quality water flowing out of Wyoming gas fields.
"This could give some leverage over Wyoming to keep those salts down," Fix said. "You'd have thought since (the drilling) is gone, things would get better. But it will take some time for the salts to leech out of the ground and out of ponds" set up to capture the wastewater.
Montana and the Northern Cheyenne Tribe first proposed the rules more than a decade ago.
Some of the nation's largest gas companies — including Marathon Oil, Anadarko Petroleum and Devon Energy — challenged the rules in federal court in 2006 after the EPA initially approved them. Wyoming officials also sued.
A U.S. District Court judge sent them back to the agency for reconsideration in 2009, and federal officials have spent the past several years re-examining the issue.
EPA Assistant Regional Administrator Martin Hestmark issued a pair of letters Tuesday approving the rules. They "protect Montana's agricultural water supply and are scientifically defensible," Hestmark wrote.
The EPA's actions do not need court approval, agency spokeswoman Lisa McLain-Vanderpool said.
It was not clear whether Wyoming and the industry will revive their lawsuits. Officials with the Wyoming Attorney General's Office and representatives of the oil and gas industry did not immediately return calls seeking comment.
The EPA's move offers a chance for the two states to cooperate going forward, Montana Department of Environmental Quality spokesman Paul Driscoll said. If differences linger, the federal agency could step in and arbitrate any disputes, Driscoll said.
The rules are just one aspect of a tussle between Montana and Wyoming over the rivers that flow north across their shared border.
A type of gas known as coal-bed methane is common in that area, and companies drilled some 30,000 wells over the last decade, primarily in Wyoming. Coal-bed methane is typically found in underground seams saturated with water, meaning millions of gallons of water must be pumped out to free the trapped gas.
The two states also have grappled over how much water each is entitled to in portions of the Yellowstone River basin, which includes the Tongue and Powder Rivers. That dispute is the subject of a pending case before the U.S. Supreme Court.