The proposed Feb. 12 sale of oil and gas leases on more than 81,000 acres of national forest, federal and private land in Colorado has sparked protests from the state, counties and environmental groups.
The sale is the most controversial since the $114 million auction of Roan Plateau leases in August.
That sale is the target of a lawsuit by environmental groups.
One major criticism of the upcoming auction is that forest parcels were chosen based on 1993 information about wildlife in the areas and dated science on how drilling might affect that wildlife.
Environmentalists argue that those older rules fail to reflect new information on species and major changes in oil-and-gas-drilling technology.
Trout Unlimited protested the sale on the grounds that it includes about 60,000 acres of prime cutthroat trout habitat.
"The problem is that just about all the cutthroat trout habitat is in this sale," said Cathy Purves, the group's science adviser.