As the cold winter months hit the North Slope, the Bureau of Land Management (BLM) is heading back out to plug four old wells in the National Petroleum Reserve-Alaska. The agency hopes the process goes more smoothly this time around.

Decades ago, the Navy and the U.S. Geological Survey drilled 136 holes, now known as legacy wells, in the National Petroleum Reserve-Alaska to explore the region’s oil and gas potential. The Bureau of Land Management now oversees the reserve and is responsible for cleaning up 50 of those wells because they could leak. That process has become a big headache.

“You have a short window of opportunity to do it and it’s very expensive,” said Stacie McIntosh, who manages BLM’s Arctic Office.

BLM has $50 million in hand to clean up the wells, but McIntosh explains the agency can only get to the holes during winter to protect the tundra’s permafrost. McIntosh says some of the wells are becoming more of a risk as time goes on.

“For most of them, they’re in a stable condition,” McIntosh said. “A lot of them, though, just have plugs that rely on ice and other things down in the well bore. And as we know, there’s the potential to be deep thaw, etc., associated with climate change.”

But climate change hasn’t been the only issue. This spring, the Alaska Oil and Gas Conservation Commission (AOGCC) sent BLM several violation notices. The state said the federal agency didn’t follow approved procedures when it attempted to clean up some of the wells. BLM said the incidents didn’t cause environmental damage but Sen. Lisa Murkowski wrote a letter to Interior Secretary Sally Jewell calling the incident “inexcusable.”

Commission Chair Cathy Foerster says the state has more confidence in BLM this time around.

“The AOGCC is optimistic that this season’s legacy well cleanup will go better than last year’s,” Foerster said. “We’re committed to working as cooperatively with the BLM as they will allow us to. We’re hopeful that they’ll be more successful this season in cleaning up the messes out there.”

This winter, BLM will return to one the wells they weren’t able to properly plug last winter: Iko Bay No. 1. But another one of the wells the Commission faulted BLM for, the Simpson Core Test 26 well, isn’t going to be worked on this winter.

“After beginning work on this well last winter and multiple attempts to set the surface plug, it did not work. So we’re going to have to go back and figure out a new approach,” said Nicole Hayes, BLM’s Legacy Wells project coordinator.

BLM has cleaned up 16 wells so far. Hayes said the agency hopes to complete up to five more “in the near future.”