"More and more we're seeing aquatic species driving water-management decisions, not just in the West, but I think that's going to creep over to the East as well," Ruhl said.
Another environmental law expert said that four decades of experience had shown the economic disruptions caused by federal protections are usually local — and worth the cost of preserving biological diversity.
"What you're always doing is balancing the cost of a single project — an oil and gas lease, a golf course — against the very existence of a species forever," said Fred Cheever of the University of Denver. "In almost every case, you have to give the species the benefit of the doubt."
Interior officials pointed to conservation work already initiated for one candidate species, greater sage grouse, as an example of efforts under way to avoid contentious restrictions. As oil and gas development expands into the ground-dwelling bird's habitat in Colorado, Montana, Wyoming and other Western states, agencies are working with landowners to preserve core areas where the birds could recover once the energy boom has passed.
Environmental groups had previously charged the Obama administration with doing little to improve on what they consider a dismal record on endangered species under President George W. Bush.
The Obama administration has listed 59 species as endangered — a rate of about 30 a year. That's up significantly from the Bush years, when the average was eight per year, but far behind the 65 species per year under the Clinton administration.
Some conservationists said Tuesday's proposal redeems the administration.
"Today's announcement greatly changes the legacy and the track record that Obama is going to have,"" said Leda Huta with the Washington, D.C.-based Endangered Species Coalition.
As part of the deal, WildEarth Guardians said it will limit the number of petitions it files to ten a year.
The group's wildlife program director, Nicole Rosmarino, said many of those petitions were bound to end up on the candidate species list under the status quo.
"We and the government agree that the day has come to address the future of the endangered species candidates. This will be an important step toward protecting the rich biodiversity in the U.S. and stemming the extinction crisis," Rosmarino said.