Wildlife habitat, endangered animals, and recreation could all be at risk in the state’s biggest public land sale in modern history.

A federal agency will offer tens of thousands of acres in northwestern Colorado that the nation’s largest elk herd relies upon for migration, foraging, and winter habitat to oil and gas companies for lease in the state’s biggest such sale in modern history.

More than 100 parcels included in a June 16 lease sale by the Bureau of Land Management encompass elk, pronghorn, and mule deer migration corridors that extend into southern Wyoming. Many sit in Moffat County, which bills itself as the “Elk Hunting Capital of the World” and relies on the pastime in part for its economic stability.

About two-thirds of the acreage in the 156,000-acre lease sale is just south of Dinosaur National Monument, a remote park that’s among the country’s over 40 certified International Dark Sky Places — areas with exceptionally dark night skies. Tourism officials in Moffat, who saw inquiries drop by more than half this spring, voiced concern that bright lights and truck traffic that accompany fossil fuel extraction could imperil this hard-won designation.

“Things like that could put that status in jeopardy,” said Tom Kleinschnitz, the county’s director of tourism. “In the long run, I think it’s important to keep these areas as pristine as possible.”

The record June lease sale contradicts the Bureau of Land Management’s stated strategy for the national monument, as well as the 2024 amendments to area plans for northwestern Colorado that strengthened habitat protections for ungulates like elk and deer and at-risk birds such as the Gunnison sage-grouse.

Risks to big game and Dinosaur National Park are just a few examples of what’s at stake for the environment, the economy, and public health. A 2,360-line spreadsheet compiled by Denver-based nonprofit Rocky Mountain Wild enumerates 17 rare plants and endangered species whose habitat could be imperiled by fossil fuel exploration and extraction.

These include the black-footed ferret, wolverine, boreal toad, and Colorado pikeminnow, and threatened plants such as the Colorado hookless cactus and Parachute penstemon. The lease sale includes acreage relied upon by other species such as the Columbian sharp-tailed grouse, greater sage-grouse, ferruginous hawk, and swift fox — all identified by state wildlife officers as being of special concern.

The June event is one of four large lease sales in Colorado since Congress passed and President Donald Trump signed a bill in 2025 that included provisions to encourage drilling on the nation’s public lands. This agenda lies in stark contrast to the pattern of leasing activity during President Joe Biden’s term — with just six sales in Colorado during his four years in office. Just several hundred acres were offered during that period.

The 2025 H.R. 1 legislation prioritized fossil fuel extraction over other uses such as recreation and conservation; mandated that federal officials hold a minimum of four lease sales each fiscal year in Alaska, Colorado, Montana, New Mexico, Nevada, North Dakota, Oklahoma, Utah, and Wyoming; shortened public comment times; and reduced the discretion land managers hold over whether to offer acreage for lease or not.

The law also decreased oil and gas royalty rates, making it cheaper to extract fossil fuels on public lands and reducing the share of profits from such natural resources to taxpayers. Colorado alone could lose $148 million in revenue from future production from about 81,000 acres that sold in 2026, according to an analysis by Taxpayers for Common Sense, a nonpartisan watchdog organization.

The push to lease tens of thousands of acres to oil and gas companies comes as bipartisan polling conducted as part of Colorado College’s State of the Rockies Project found a majority of voters in eight Western states want their congressional representatives to prioritize conservation over energy development on public lands.

About 21 million acres of public lands overseen by the Bureau of Land Management are leased for oil and gas development already, according to fiscal 2025 statistics on the agency’s website. Only 12 million of those acres are actually producing fossil fuels.

This discrepancy underscores a concern of conservation groups that during the decade that energy companies hold federal oil and gas leases, the parcels by law cannot be managed for other uses such as sensitive habitat, wilderness character, or recreation.

“Folks need to understand the long-term impacts of a rush to lease so much public land,” said Peter Hart, legal director of the Wilderness Workshop, which works to conserve wildlife and the wilderness.

“Once those leases are issued they are very hard to get rid of — they stay on the land for a long time, even if they aren’t developed.”

In response to issues raised in a 106-page comment letter filed March 13 by the Wilderness Workshop and 17 other organizations, the Bureau of Land Management wrote in an environmental assessment that it would conduct additional site-specific analysis of each parcel in the Colorado sale if a company files for a drilling permit.

The agency also pointed out repeatedly in its 646-page report that “risks are reduced through the careful review of drilling and completion plans for proposed wells by both the BLM” and Colorado’s Energy and Carbon Management Commission.

Federal officials removed four parcels and reduced a fifth, for a total of about 4,800 acres, from the initial sale offering, citing a recent decision by the Interior Board of Land Appeals. These parcels included habitat for the greater sage-grouse and Columbian sharp-tailed grouse as well as high priority habitat for big game. Numerous other parcels with similar characteristics remain in the sale.

The environmental assessment also noted that agency officials would apply stipulations to leases issued for sensitive parcels aimed at protecting animals, plants, cultural resources, and fish.

Even so, conservation groups that closely monitor what’s at stake in oil and gas lease sales said that federal land managers have significantly less leeway at the permitting stage to move oil and gas operations, add conditions of approval, or to cancel a lease altogether. Together with these limitations is an inability for these officials to remove parcels that were deferred from past sales because they included habitat for sensitive species.

“During the first Trump administration, there was a sale that was initially proposed to be much larger than this and the state Bureau of Land Management was able to use its discretion to defer parcels that were inappropriate because of greater sage-grouse conflicts,” said Alison Gallensky, a conservation geographer at Rocky Mountain Wild.

“Now, they are being forced to offer a much larger sale than that one turned out to be,” she added.