State attorneys general in Oregon, Washington and California and two Oregon-based environmental groups are asking federal energy regulators to reconsider their approval of a natural gas pipeline project that would increase the flow of gas through the Northwest.

Federal regulators voted unanimously Oct. 19 to allow Calgary-based TC Energy to expand the capacity of its 1,400-mile-long GTN Xpress gas pipeline through Oregon, Idaho, Washington and northern California. The expansion would allow 150 million more cubic feet of gas to be delivered to the region each day.

It currently transports about 2 billion cubic feet of gas from western Canada to West Coast consumers each day – enough to power 5 million U.S. homes each day, according to the U.S. Energy Information Administration.

Oregon Attorney General Ellen Rosenblum, Washington Attorney General Bob Ferguson and California Attorney General Rob Bonta and lawyers for Rogue Climate in southern Oregon and Hood River-based Columbia Riverkeeper filed petitions with the Federal Energy Regulatory Commission.

Environmentalists on Tuesday asked for a rehearing from the commission, and accused commissioners of violating two federal laws meant to mitigate environmental harm and ensure gas projects are in the public interest. The state attorneys general filed their petition Wednesday.

Natural gas is almost entirely made up of methane, a potent greenhouse gas and a main contributor to global warming. It’s primarily used to heat homes and businesses, including at least a quarter of all homes in Oregon, according to the state’s Department of Energy. Natural gas produces water vapor and carbon dioxide when it is burned.

The state attorneys general claim that TC Energy has not demonstrated the long-term demand for the increase in gas, and that the project is counter to the region’s climate laws, which require greenhouse gas emissions to decrease at least 90% in Oregon by 2050 and 95% in Washington by the same year. In Oregon, at least 26% of that reduction will have to come from natural gas.

Washington Gov. Jay Inslee said in an online news conference on Wednesday that he requested that Ferguson file the petition to “right an abusive decision” that will impact people in Washington and the Northwest, and to ensure federal regulators honor climate laws passed in West Coast states.

“This is the express intent of the entire Western Coast of the United States,” Inslee said. “We kind of thought the West Coast is still part of the United States, and our intent to reduce the use of gas over time ought to be recognized. It has not been. We don’t think FERC’s done its job,” he said.

Federal energy commissioners have 30 days to respond to the petitions. If the commission ignores or denies the request, the groups said in a news release they will challenge the commission’s decision in federal court.

Michael Tade, a spokesperson for TC Energy, previously told the Capital Chronicle that the company appreciated the approval from federal regulators to upgrade the pipeline, because it needs to expand its carrying capacity due to increased demand from consumers.

Environmental groups said federal regulators ignored widespread concerns.

“FERC failed to resolve critical questions raised by states, senators, and thousands of people across the Northwest,” Audrey Leonard, staff attorney for Columbia Riverkeeper, said in the release.

The federal energy commission approved the pipeline project after more than a year of opposition from regional Democratic leaders – including Oregon and Washington governors, attorneys general and U.S. senators – and more than a dozen environmental and social justice groups.

Idaho’s congressional delegation supports the pipeline project, as does Oregon state Rep. Greg Smith, R-Heppner. And Oregon’s two Republican U.S. representatives, Lori Chavez-DeRemer and Cliff Bentz, urged the commission in an Oct. 10 letter to allow the pipeline expansion.

The expansion of the GTN Xpress would result in an additional 3.47 million metric tons of carbon dioxide being released for at least the next 30 years, according to a joint filing opposing the pipeline that was submitted to the federal commission in August 2022 by the three state attorneys general.