The Biden administration moved Friday to protect 28 million acres of public lands in Alaska from oil and gas drilling, mining and other industrial activities that could threaten Alaska Native communities, vulnerable wildlife and pristine ecosystems.

The move bolsters President Biden’s conservation record as he seeks a second term, and it may help him court climate activists who were angered by his approval last year of the Willow oil drilling project on Alaska’s North Slope. But his latest decision is certain to anger Alaska lawmakers, including Rep. Mary Peltola, a popular Democrat who faces a tough reelection race that could determine which party controls the House.

In a final environmental impact statement released Friday, the Interior Department’s Bureau of Land Management outlined several options for managing 28 million acres of public property across Alaska. The “preferred alternative” calls for retaining protections for these lands that the Trump administration had proposed revoking.

In a separate announcement Friday, the Bureau of Land Management finalized its decision to block a controversial road in northern Alaska. Although Ambler Road would be crucial to operating a planned copper and zinc mine, the agency determined that its construction would cause irreparable harm to Alaska Native communities and the already declining Western Arctic caribou herd.

“Today, my Administration is stopping a 211-mile road from carving up a pristine area that Alaska Native communities rely on, in addition to steps we are taking to maintain protections on 28 million acres in Alaska from mining and drilling,” Biden said in a statement. “These natural wonders demand our protection.”

The 28 million acres under consideration stretch across five regions in Alaska, including the Bristol Bay watershed, one of the world’s biggest salmon spawning grounds. They also provide critical habitat for brown bears, caribou, muskox and hundreds of migratory bird species.

The fate of these areas has fostered a fierce debate for more than a half-century. In 1971, Congress passed the Alaska Native Claims Settlement Act, which directed Interior to transfer millions of acres of land to Alaska Native corporations and villages. But Section 17(d)(1) of the law allowed Interior to decide whether to permanently protect some other areas, commonly known as D1 lands.

In the final days of the Trump administration, then-Interior Secretary David Bernhardt, a former oil and gas lobbyist, proposed scrapping the protections for 28 million acres of D1 lands. But Trump officials did not finalize the proposal before leaving office, prompting Biden officials to pause its implementation while studying its environmental impacts.

In the analysis released Friday, BLM found that revoking some or all of the protections would probably harm hunting, fishing and other subsistence activities in 44 to 117 Alaska Native communities. It also found that lifting the protections could have lasting negative effects on wildlife, vegetation and permafrost. The analysis is not a final decision. Interior Secretary Deb Haaland plans to issue a final decision based on the findings in the coming weeks, the agency said in a news release.

If former president Donald Trump wins a second term, his administration would probably propose nixing the protections yet again. Doing so, however, could inspire a lengthy legal battle with environmental advocates and some tribes.

At least 183 Alaska Native villages are within 50 miles of D1 lands. Many of these villages had urged the Biden administration to retain the protections, saying these areas are essential to their cultures and subsistence lifestyles. “D1 lands in the Yukon-Kuskokwim region are vital to our people’s way of life - these protections ensure future generations will be able to live safely with and on the land, carrying our customary and traditional knowledge,” said Anaan’arar Sophie Swope, executive director of the Mother Kuskokwim Tribal coalition, a group supporting tribes in the Yukon-Kuskokwim Delta region.

Millions of acres of D1 lands in southwestern Alaska surround a controversial mining project. If completed, the Donlin Gold Project would be one of the world’s largest open-pit gold mines, producing an estimated 1 million ounces of gold a year.

Alaska politicians in both parties have voiced strong support for the planned mine, saying it could provide hundreds of jobs and economic development in one of the poorest parts of the state. But environmental groups and some tribes have fought the project, saying its construction could destroy habitat for wild salmon in the Yukon-Kuskokwim Delta.

“We can eat a lot of salmon, but we can’t eat gold,” said Eugene Paul, chairman of the Bering Sea-Interior Tribal Commission, which represents more than two dozen local tribes.

Kristina Woolston, a spokeswoman for Donlin Gold, referred inquiries about the project to Calista Corp., an Alaska Native corporation that owns the mineral rights to the site. Thom Leonard, a spokesman for Calista, rejected allegations that the mine would harm salmon or other fish species.

“Calista will continue to place a priority on environmental protections,” Leonard said in an email. “Modern Alaska mines operating today, such as Red Dog and Fort Knox, have a strong track record for protecting and even increasing local fish populations.”

The Bureau of Land Management also dealt a blow to another contested mine on Friday. The Biden administration’s decision to block Ambler Road was not entirely unexpected. In April, the bureau released an analysis that found the road could threaten the lifestyles of more than 60 Alaska Native communities while imperiling caribou herds.

If approved, the road would have stretched 211 miles, crossing 11 major rivers to reach the planned open-pit mine. Twenty-six of those miles would have carved through Gates of the Arctic National Park and Preserve, sending giant trucks rumbling through wild lands where tens of thousands of caribou migrate. Frank Thompson, the tribal president of Evansville, a Native village near the eastern end of the road’s proposed path, said the decision would safeguard land that his tribe has lived on for thousands of years. “Thank you to all those that helped in this fight for our survival,” he said.

Kaleb Froehlich, managing director of mining venture Ambler Metals, slammed the decision, saying it would deprive Alaska of “good-paying jobs, revenues and investment.” He also warned that it would undermine the Biden administration’s own goal of strengthening U.S. supply chains for critical minerals used in clean-energy technologies.

Froehlich suggested that the company would consider challenging the move in court. “We remain committed to the project and will explore all legal, legislative, and regulatory avenues to move it forward,” he said. Lawmakers from Alaska have also sought to block the move legislatively. Sen. Dan Sullivan (R-Alaska) has introduced an amendment to the National Defense Authorization Act, the annual defense policy bill, that would override the Biden administration’s rejection of Ambler Road.

“As we continue to work through NDAA, we will seek to affirm permanent private road access that will make these resources available in a way that works for stakeholders in the area,” Peltola said in a statement. While Biden’s actions Friday may help him shore up his support among climate activists, many of them remain bitter over his approval of Willow, the biggest U.S. oil project. ConocoPhillips, the company behind the project, hopes to produce 576 million barrels of oil over 30 years in the National Petroleum Reserve-Alaska, the nation’s largest piece of public land.