Interior Secretary Ryan Zinke has recommended to the White House that President Trump move to shrink six national monuments, four on land and two protected areas in the oceans, according to leaked documents made public over the weekend.

In August, Zinke completed his four-month review of national monuments established during the last 20 years, but neither the Interior Department nor the White House released the recommendations to the public. Leaked copies of Zinke’s memorandum, titled “Final Report Summarizing Findings of the Review of Designations Under the Antiquities Act,” were obtained independently by the Washington Post and the Wall Street Journal and posted online late Sunday. 

The document reveals that Zinke is urging the president to shrink, by unspecified areas, four national monuments in the West: Grand Staircase–Escalante and Bears Ears in Utah, Cascade-Siskiyou on the Oregon-California border, and Nevada’s Gold Butte. Two oceanic monuments, Pacific Remote Islands and Rose Atoll, might also be reduced. 

Zinke is also recommending changes to the management guidelines of a total of 10 monuments to include activities such as “active forest management,” grazing, and commercial fishing. Monuments that could experience loosened rules include the six named above as well as Organ Mountains–Desert Peaks and Rio Grande del Norte in New Mexico, Maine’s Katahdin Woods and Waters, and Northeast Canyons and Seamounts in the Atlantic Ocean.

Conservation groups quickly expressed outrage. “Secretary Zinke’s proposal threatens the very idea of shared public spaces open to all,” Sierra Club executive director Michael Brune said in a statement. “Leaving the protection of Native American sacred sites, outdoor recreation destinations, and natural wonders to the goodwill of polluting industries is a recipe for disaster. Secretary Zinke has just sold out public lands and all the people who rely on them." 

No president has ever attempted such a sweeping rollback of national monuments established by his predecessors. Legal scholars say it is unclear whether the president has the authority to dramatically redraw existing monuments. Local and national conservation groups are already preparing lawsuits to challenge the president should he attempt to follow through on Zinke’s recommendations. 

“We believe the Trump administration has no legal authority to alter or erase protections for national treasures,” Jamie Williams, president of the Wilderness Society, said in a statement. “If President Trump acts in support of these recommendations, the Wilderness Society will move swiftly to challenge those actions in court. We urge the president to ignore these illegal and dangerous recommendations and instead act to preserve our natural wonders that are at the core of a great nation.”