New legal action aims to head off a Trump administration plan to open up to 24m acres of federal lands to cattle grazing, which opponents characterized as a gift to big agriculture and said could cause a spike in deaths among already imperiled wolves, grizzlies, steelhead salmon and other wildlife.

The plan also calls for opening up parts of Grand Canyon national park, and other sensitive landscapes. Cattle destroy critical habitats for wildlife because they strip land bare of essential vegetation and pollute streams with feces, urine, sediment and carcasses. Meanwhile, park rangers and ranchers often kill grizzly bears and other predators who prey on cattle, despite that ranchers and the government pushed the cattle into the predators’ home range.

The degree to which livestock grazing degrades ecosystems makes it a top threat to animals and plants at risk of extinction, environmental advocates say. These issues exceed the combined impacts of logging and mining on protected species.

The Center for Biological Diversity (CBD) alleges in a notice of intent to sue that the Trump administration fast-tracked the plan without consulting the US Fish and Wildlife Service, which, under the Endangered Species Act, must review the plan’s impact on protected species.

“The federal grazing program is already a disaster for endangered species and the places they live,” said Andrea Zaccardi, carnivore conservation legal director at CBD. “Expanding grazing across 24m more acres will make that devastation even worse and likely drive more animals and plants to extinction.”

Trump implemented the new plan through a memorandum of understanding signed in March by the US Bureau of Land Management, and would use emergency authority to fast-track grazing where it is not currently allowed.

Zaccardi said it is unclear why the administration is aggressively opening up the land. While there have been isolated instances of individual ranchers asking for some “allotments” to be opened to grazing, there is no industry-wide effort that environmental groups are aware of, she added.

The Bureau of Land Management declined to comment, but the new policy states that it plans to implement “a goal of a no net loss of Animal Unit Months within allotments” and maximizing “authorization of livestock use” across vast western rangelands.

The move comes as meat prices remain high, but while the harm to wildlife would probably be significant, advocates say the benefit to the livestock industry would be small – grazing on public lands accounts for just 2% of the nation’s beef cattle.

About half of 2,400 stream miles of endangered species habitat surveyed by CBD since 2017 show significant damage from livestock. Meanwhile, surveys of more than 200 forest service and Bureau of Land Management grazing allotments in Arizona and New Mexico show damage to critical habitat from authorized, unauthorized, trespassing and feral livestock. The cattle are also a threat to fish because they eat the riparian vegetation along streams’ edges that keeps the water cool.

Among the most alarming potential fallout is how the plan would foster conflict among cattle, ranchers and predators, advocates say. Congress in the 1930s authorized the wildlife services to kill wildlife at the request of private landowners, including if they threaten livestock. Predators, like grizzlies, covered by the Endangered Species Act, are not exempted, and Zaccardi said the law is a major threat to the bears, gray wolves and Mexican wolves that are particularly prone to preying on cattle.

State and federal agents “lethally remove” hundreds of thousands of animals annually in what some advocates have previously characterized as a “bloodbath”. Some of the lands listed in the memorandum have not been used for grazing for decades and many predators likely live there, Zaccardi said.

“The likelihood of this increasing conflict with predators is extremely high,” she added.

The plan also contains “unusual provisions to benefit” big agriculture, said Chandra Rosenthal, western lands and rocky mountain advocate with the Public Employees For Environmental Responsibility (Peer) non-profit.

Among those is the establishment of “immersion and training programs for new and existing federal employees to the daily life, decisions, and dilemmas of ranchers”, Peer noted. The memorandum makes little mention of rangeland environmental conditions and instead the plan will “deregulate”, “streamline” and “incorporate beneficial flexibility”.

“The Trump administration does not appear to care that commercial livestock grazing exacts an enormous toll on native ecosystems and wildlife throughout the American West,” Rosenthal said in a statement.

The plan would also open lands in popular national parks and monuments, including Grand Staircase-Escalante national monument, Canyons of the Ancients national monument in Colorado, and Arizona’s Sonoran desert national monument.

The Trump administration has 60 days to respond to the notice of intent to sue. If it fails to, then CBD would ask a federal judge to order the Trump administration to review how the plan would impact protected wildlife, as is required under the Endangered Species Act.