Alaskan Joe Balash, a Trump administration leader on ANWR drilling, is leaving the Interior Department

Joe Balash, an Alaskan with a key role in efforts to drill for oil in the Arctic National Wildlife Refuge, is leaving his post as an assistant secretary at the Interior Department.

Balash said he will resign Aug. 30 as Interior’s assistant secretary for Land and Minerals Management, according to a resignation letter dated Tuesday and addressed to President Donald Trump.

Balash said in a text early Wednesday that an “opportunity” has come along that he can’t ignore.

He had little else to share about the reason for his departure.

“I’ll have more to say about my next adventure once I have fully separated from the department," he said. "I’m leaving on good terms — it’s all positive.”

Balash has moved aggressively to have the federal government host its first lease sale in ANWR’s coastal plain by the end of this year, setting the stage for drilling there after Congress approved it in 2017.

The Bureau of Land Management, an agency Balash oversees, expects to release a final environmental review early next month that recommends a preferred leasing plan for the ANWR coastal plain. The Interior Department could issue a final decision 30 days after that, opening the door for the lease sale, said Lesli Ellis-Wouters, a BLM spokesperson.

Balash, who oversees oil, gas and mining activities on federal lands, said his absence will not hurt the government’s efforts to permit oil and gas activity in the coastal plain of the 19-million-acre refuge.

“The work is mostly done,” he said by text. “I put together a great team (to) do the work -- and they will remain.”

Alaska’s congressional delegation has often highlighted Balash’s role as critical to the state’s efforts to responsibly develop its natural resources. Sen. Dan Sullivan, to whom Balash was chief of staff until he joined Interior, has said Balash’s role in the Trump administration, alongside other Alaskans, is good for the state’s economic prospects.

Sullivan on Wednesday said Balash worked tirelessly at Interior “to promote the goal of American energy dominance, and understood that Alaska was key to that goal,” Sullivan said. "In doing so, he has helped set Alaska up for success for years to come. I wish him all the best in his future endeavors.”

Sen. Lisa Murkowski praised Balash for his work on ANWR leasing and for making more federal land eligible for conveyance to the state and Alaska Native corporations, following through on longstanding commitments in federal law.

“Alaska is in a better place because of his leadership and we thank him for his many years of public service,” Murkowski said, adding that the state’s strong ties with Interior will continue.

Balash’s departure will be a “real loss for Alaska,” the Alaska Support Industry Alliance said Wednesday. “Balash was working hard to advance opportunities for drilling in ANWR,” said the trade group, a supporter of resource development.

But Balash has angered conservation groups. And House Democrats are investigating the administration’s rapid push for drilling in ANWR amid questions that Balash may have been involved in suppressing scientists’ concerns about the environmental impacts of drilling, following an investigation by Politico.

Balash said by text on Wednesday that politics has not superseded science as the federal government moves toward a lease sale in the refuge. If that were the case, the administration would have allowed a seismic survey in the refuge last winter, despite concerns from scientists about potential impacts to polar bears from ground-vibrating trucks used to study rock formations.

“If politics was trumping on science on ANWR, we would have permitted the seismic last year,” he said. “We did not.”

Lena Moffitt, with the Sierra Club, said in a statement Wednesday that Balash has "spearheaded efforts to suppress science, ignore indigenous rights, and sell off the Arctic refuge for drilling at all costs.”

Interior Secretary David Bernhardt said in a Tweet on Tuesday that he and Trump thank Balash for his “exemplary service to the American people.”

Balash said in his resignation letter that implementing Trump’s executive orders to promote energy independence and economic growth has a been a “career highlight.”

Balash said his accomplishments include guiding the first-ever joint-agency federal decision to advance development at Donlin gold mine in Southwest Alaska, preparing the environmental documents for the lease sale in ANWR, and approving the first-ever oil production facility in federal waters outside Alaska, Hilcorp’s Liberty project.

Balash’s announcement came the day before the New York Times published the results of an investigation raising doubts about the Trump administration’s promise of a windfall for the federal government if drilling takes place in ANWR.

The article does not say that Balash, named to his post in July 2017 by Trump, was involved in those efforts to put a promising spin on the value of drilling there.

Drilling in the refuge over the next decade may produce as little as $45 million, the newspaper said, a figure based on the value of past state and federal lease sales on the North Slope since 1999.

That’s much lower than the $1.8 billion the White House touted in spring 2017 -- before Balash was named to his post -- or the $900 million currently estimated by the Congressional Budget Office.

The article says Interior officials in 2017 removed references to disappointing test wells drilled near the refuge from a final plan to update the refuge’s oil reserves.

Balash said he’s “never seen” any of the drilling results from wells near the refuge.

Balash was raised in North Pole and served as natural resource commissioner under previous Gov. Sean Parnell.