Interior Secretary Ryan Zinke recommended Thursday that President Trump alter at least three national monuments established by his immediate predecessors, including two in Utah, a move expected to reshape federal land and water protections and certain to trigger major legal fights.

In a report Zinke submitted to the White House, the secretary recommended reducing the size of Utah’s Bears Ears National Monument and Grand Staircase-Escalante, as well as Oregon’s Cascade-Siskiyou National Monument, according to multiple individuals briefed on the decision. President Clinton declared the 1.9 million-acre Grand Staircase-Escalante in 1996, while President Obama designated the 1.35 million-acre Bears Ears last year. Cascade-Siskiyou, which now encompasses more than 113,000 acres, was established by Clinton shortly before leaving office and expanded by Obama in January.

Trump had ordered Zinke to examine more than two dozen sites established by three presidents under the 1906 Antiquities Act, including Republican George W. Bush. The nearly four-month process pitted those who have felt marginalized by federal actions over the past 20 years against backers who see the sites as bolstering tourism and recreation while safeguarding important relics, environments and species.

The Interior Department did not release specifics on Zinke’s recommendations, instead releasing a report summary that described each of the 27 protected areas scrutinized as “unique.”

But the secretary’s proposal takes direct aim at a handful of the nation’s most controversial protected areas out West, according to several individuals who asked for anonymity because the report has yet to be made public. Zinke, who had called for revising Bears Ears’ boundaries in an interim report in June, is recommending a “significant” reduction in the size of the monument, an administration official said.

“No president should use the authority under the Antiquities Act to restrict public access, prevent hunting and fishing, burden private land, or eliminate traditional land uses, unless such action is needed to protect the object,” Zinke said in a statement. “The recommendations I sent to the president on national monuments will maintain federal ownership of all federal land and protect the land under federal environmental regulations, and also provide a much needed change for the local communities who border and rely on these lands for hunting and fishing, economic development, traditional uses, and recreation.”

A White House official confirmed that Trump had received the report but would not say when it would be released or when the president would act on Zinke’s recommendations.

“Comments received were overwhelmingly in favor of maintaining existing monuments and demonstrated a well-orchestrated national campaign organized by multiple organizations,” Zinke said in the statement. He acknowledged supporters’ point that monuments can bring economic benefits to local communities.

But he also noted opponents’ concerns that designations had translated into reduced public access, confusing management plans “and pressure applied private land owners … to sell.”

Zinke did not recommend abolishing any monument. But some of the key constituencies most critical of sweeping restrictions for federal lands and waters – ranchers, fishing operators and local Republican politicians – apparently won key concessions in his final set of recommendations.

“There’s an expectation we need to look out 100 years from now to keep the public land experience alive in this country,” the secretary told the Associated Press. “You can protect the monument by keeping public access to traditional uses.”

Environmental groups made clear that they would file legal challenges in an effort to preserve these sites’ existing boundaries and protections. While Congress can alter national monuments easily through legislation, presidents have reduced their boundaries only on rare occasions.

Woodrow Wilson nearly halved the acreage of Mount Olympus National Monument, which Theodore Roosevelt had established six years earlier. In 1938, the U.S. attorney general wrote a formal opinion saying the Antiquities Act authorized presidents to establish a monument but did not grant them the right to abolish one, and several legal scholars argue that Congress indicated in the Federal Land Policy and Management Act of 1976 that it reserved the right to alter any existing monument.

“Zinke’s sham review was rigged from the beginning to open up more public lands to fossil fuel, mining and timber industries,” said Randi Spivak, public lands director for the Center for Biological Diversity. “He and Trump will not be allowed to rob Americans of their public lands. Any effort to change national monument boundaries or reduce protections will be challenged.”

Tribal officials have lobbied hard to preserve Bears Ears, which boasts extensive ancestral Pueblo artifacts and rock art. Seven tribes in Utah and the Fort Peck Assiniboine & Sioux Tribes of Montana, which counts Zinke as an adopted member, have passed resolutions this month calling for the monument’s boundaries to remain in place.

But many western Republicans criticized large protected areas such as Bears Ears as a distortion of the law’s original intent. In a call with reporters on Thursday, House Natural Resources Committee Chairman Rob Bishop, R-Utah, said that “Congress never intended one individual to unilaterally dictate land management policies for enormous swaths of federal land.”

“It’s about how we protect our resources, not if we protect them,” said Bishop, noting that Obama had applied his authority under the Antiquities Act to more than 550 million acres of land and sea. “That’s 190,000 acres of land and water locked up for every day he was in office.”