The U.S. Forest Service has lost nearly $600 million through its management of Tongass National Forest in Alaska, according to a new report.

The study by the nonpartisan group Taxpayers for Common Sense calculated the losses through roadbuilding and timber sales, CoastAlaska reported Monday.

The average net loss has been about $30 million annually over the past 20 years, the report said.

The U.S. Forest Service did not comment on the group’s report.

Taxpayers for Common Sense warned that a rollback of the federal Roadless Area Conservation Rule would accelerate the trend of the forest costing taxpayers hundreds of millions of dollars in federal subsidies.

Alaska’s U.S. senators have pushed for a rollback of the federal rule to open more areas of Tongass to logging, arguing it would help the region’s economy.

The U.S. Department of Agriculture is expected in the coming weeks to decide whether to formally roll back the Roadless Area Conservation Rule in Alaska.

“The system is clearly broken if we are so underwater with our timber sales,” said Autumn Hanna, vice president of Taxpayers for Common Sense.

The group cited a 2016 report by the Government Accountability Office detailing the average annual cost of the Tongass timber program without factoring in the cost of building access roads.t

The group projected a net loss of at least $180 million despite the forest service’s projection of an additional 300 million board feet (91 million meters) in the next four years.

“We need to reform the timber program first, and just opening up more areas will not help taxpayers,” Hanna said.