A conservation organization has filed formal notice of its intent to sue the U.S. Fish and Wildlife Service for a rule opening millions of acres in national wildlife refuges and hatcheries to hunting and fishing, and expanding hunting on more than 100 other federal properties.

On Tuesday, the Center for Biological Diversity formally filed its intent to sue the agency for rules they say “authorizes damaging practices like the use of lead ammunition and killing of ecologically important top predators such as mountain lions.”

“The rule opens hunting on numerous refuges previously reserved for protecting endangered species or other wildlife. [Tuesday’s] notice asserts that the agency has violated the Endangered Species Act by failing to analyze and mitigate harmful impacts from the hunting expansion on endangered wildlife, such as grizzly bears, ocelots and whooping cranes,” the group said in a release.

The expansion will allow hunters to use lead ammunition, which was prohibited at the end of the Obama administration, but then reinstated by former Secretary of the Interior Ryan Zinke. The Center for Biological Diversity, a nonprofit organization with more than 1.7 million members, claims species like grizzly bears are now at risk from being killed in mistaken-identity or self-defense shootings by hunters, such as those targeting black bears in grizzly bear territory.

“Rare and beautiful animals like grizzly bears and ocelots now face increased risks of poaching, disturbance, ingestion of toxic lead shot and more. It’s tragic, and I’m hoping the court will set things right,” said Collette Adkins, the center’s carnivore conservation director.

The Fish and Wildlife Service has 60 days to respond to the notice. If it does not, the conservation group can then sue under the Endangered Species Act. There are seven National Wildlife Refuges in Wyoming, the closest being the National Elk Refuge near Jackson. The Jackson National Fish Hatchery is also in Teton County.

Critics of lead ammunition claim the toxic substance is dangerous to people and wildlife even at very low levels. Exposure to it can cause a range of health effects, from acute poisoning and painful death to long-term problems such as reduced reproduction, inhibition of growth and damage to neurological development. Recent studies show eagles are highly susceptible to lead from hunting and the U.S. Fish and Wildlife Service has several rules forbidding its use near waterfowl habitat.

“Non-lead ammunition is widely available at gun and sporting-goods stores,” Adkins said.