The Interior Department in the past week sent to the White House for review three rules that could significantly affect the way habitat is protected for threatened and endangered species.
One of the rules will determine how the Fish and Wildlife Service decides which lands to set aside as critical habitat and which lands to leave available for economic development.
Another will redefine the threshold for when projects such as mines, dams, timber harvests or ranching operations would adversely modify critical habitat, a litmus test of sorts for whether such activities are allowed to move forward.
It is unclear what the third rule entails.
The administration said it cannot release drafts of the rules to the public, because none of them is complete. But it said each is designed to improve implementation of the Endangered Species Act and reduce conflicts.
"By increasing clarity and consistency in the interpretation and implementation of these regulations, we're seeking to increase our effectiveness in recovering species while reducing the frequency and intensity of ESA conflicts," said Chris Tollefson, a spokesman for FWS.
The proposed rule to redefine what constitutes "destruction or adverse modification" of critical habitat has been in the works since at least two years ago and has been a source of legal conflict for more than a decade.
The Endangered Species Act requires the government to protect critical habitat for endangered species and prohibits destruction or adverse modification of that habitat. The big question is how to define "adverse modification," an inherently ambiguous term.
The definition could have a major impact on species recovery, environmentalists say. "It's the only protection in the act that explicitly protects against habitat loss, which is the leading cause of species imperilment," said Bill Snape, a senior attorney for the Center for Biological Diversity.
Since the Reagan administration, the agency has defined destruction or adverse modification of critical habitat as "a direct or indirect alteration that appreciably diminishes the value of critical habitat for both the survival and recovery of a listed species."
But the 9th U.S. Circuit Court of Appeals in 2004 said that definition would "drastically narrow the scope of protection commanded by Congress under ESA."
Environmental groups want the government to expand protections to aid species' recovery by changing the definition to "survival or recovery."
"This would give 'recovery' independent meaning," said Ya-Wei Li, an endangered species adviser for Defenders of Wildlife. "This is a long-overdue revision."
Environmental groups in a 2010 letter to Interior and the Commerce Department urged the agencies to define adverse modification as anything that "diminishes the value of any portion of any area of designated critical habitat for either the survival or recovery" of species.
But one attorney who is an expert on endangered species law speculated that such a definition is probably more expansive than what FWS envisions.
"That's really a far step," the attorney said. "I would be surprised to see the service go that far, given the potential conflict that could create for other federal activities."
Another pending rule before the White House Office of Management and Budget would "articulate the purpose of critical habitat" and describe when and how it should be designated, according to the White House.
"This policy will help provide clarity and consistency in the designation of critical habitat in an effort to ensure that the purposes of the Endangered Species Act are fully met," the White House said.
The policy could determine how Interior secretaries exercise their discretion to exclude certain lands from critical-habitat designations, which has engendered intense conflicts in the case of species including the northern spotted owl and bull trout in the Pacific Northwest.
While FWS is not allowed to consider economic impacts when deciding whether to list a species under ESA, when designating critical habitat it must measure environmental benefits against impacts to the economy and national security.
Li of Defenders said a briefing with FWS more than a year ago suggested the agency would try to make its regulatory definition of critical habitat more consistent with what was mandated by Congress.
"Their approach is to take a somewhat more holistic view of critical habitat, which is closer to the statutory definition," he said.
The agency may also address to what extent unoccupied habitat should be considered critical to a listed species.