A recent academic study conducted for the Bureau of Land Management concludes that large-scale oil and natural gas drilling in northeast Wyoming's Powder River Basin is wiping out greater sage grouse populations that were flourishing less than 20 years ago.

The study conducted by researchers at the University of Montana also concluded that Wyoming's "core sage grouse area" approach is not having much of an impact in the basin, and that immediate steps must be taken to protect critical breeding areas, called "leks," that are essential to the survival of the imperiled bird.

The wide-ranging 46-page study, conducted for BLM's Buffalo Field Office in northeast Wyoming, also estimates that drilling activity can affect grouse more than 12 miles away, suggesting buffers around leks need to be larger, and that evaporation ponds associated with natural gas drilling have helped spread West Nile Virus outbreaks that have caused widespread grouse deaths.

The Feb. 27 study -- obtained last week by the Powder River Basin Resource Council through a Freedom of Information Act request -- evaluated millions of acres of grouse habitat in the basin, which is one of the most heavily drilled regions in the West.

But the study is designed to assist BLM as it works to develop a "National Greater Sage-Grouse Planning Strategy" that will guide how the agency manages the estimated 47 million acres of grouse habitat under its control.

State and federal regulators are desperately trying to preserve the grouse after the Fish and Wildlife Service determined in 2010 that the chickenlike bird warrants Endangered Species Act protection, placing it on a list of "candidate species" whose status is reviewed every year. Federal and state leaders across the West have said such a listing would damage the region's economy, including its vital ranching, agricultural and energy sectors.

But the latest study notes that grouse populations in the Powder River Basin have declined 82 percent in the past decade, and the researchers warn that increased drilling activity coupled with another major West Nile Virus outbreak could reduce grouse in the region to a state of "functional extinction."

"It's been an absolute free fall for the grouse in the region since 2001," said David Naugle, a University of Montana wildlife biologist in Missoula who co-authored the study.

"If they want to keep sage grouse in that basin long term, they're going to have to restore the basin at the scale in which they drilled it," Naugle added. "Whether there's the human will, capacity and funding to do that is the next chapter in the Powder River Basin story."

A 'wake-up call'

Environmentalists hailed the new study, saying it bolsters their calls for BLM to better manage and plan energy development on federal land near critical grouse habitat.

Erik Molvar, a wildlife biologist with the Biodiversity Conservation Alliance in Laramie, Wyo., called the study "a wake-up call for the BLM" to do more to protect grouse in the basin, and said failure to do so "could easily cause the Endangered Species listing of the grouse all by itself."

Bob LeResche, a Powder River Basin Resource Council board member and a wildlife biologist by training, concurred.

"We now see so clearly that what we warned about regarding the rush to develop without proper planning, careful phasing of development and requiring timely reclamation is having lasting impact on an iconic prairie species," LeResche said. "BLM must heed the results of this study and take immediate action to buffer the sage grouse core and connectivity areas in the Powder River Basin."

But the latest study is not all bad news. The researchers make a number of recommendations that they say could save Powder River Basin grouse from extinction.

Among them is the need to immediately restore areas surrounding plugged or abandoned drilling sites. "Focusing restoration where plugged and abandoned wells are clustered would increase the size of habitats available to birds, thus enhancing the chance of increasing their abundance and distribution," according to the study.

Another recommendation is for the state of Wyoming to be more aggressive in marking core sage grouse areas before drilling activities are planned or conducted. The core area boundaries in the Powder River Basin first approved in 2008 were drawn after large-scale oil and gas development had already been under way for years.

"Our findings do not negate the benefits of core areas, in general," the study states. "However, to achieve maximum effectiveness, core areas must be constructed proactively by conserving high quality habitat, not reactively by drawing borders around planned and existing development."

Increasing conservation buffers

Among the most significant findings of the latest study is that grouse are affected by drilling activity as far as 12 miles away -- an indication, environmentalists say, that Wyoming and other states need to establish larger buffer zones around leks.

"Every new study on sage grouse in oil and gas country indicates that we must protect leks with increasingly larger buffers," said Mark Salvo, director of WildEarth Guardians' Sagebrush Sea Campaign. "We've been saying it for years: Sage grouse are a landscape species; they need large expanses of undeveloped sagebrush to persist."

That view is sure to be a major source of contention with the oil and gas industry.

In public comments about BLM's planned environmental impact statement (EIS) analyzing strategies for the national sage grouse policy, industry representatives chafed at a recommendation by the agency's National Technical Team calling for no surface disturbance within 4 miles of grouse leks (EnergyWire, March 28).

"These restrictions are not supported by science and are much more onerous than even the most restrictive management strategies used across the range of the species," according to comments submitted last week to BLM by Denver-based Western Energy Alliance.

But the latest Powder River Basin study notes that expanded drilling in the basin could significantly affect sage grouse leks.

For example, the researchers calculate that the number of large-scale leks in the region would decline as much as 70 percent if coalbed methane natural gas development reaches densities of four wells per square mile, according to the study.

"Breeding sage-grouse populations are severely impacted at oil and gas well densities commonly permitted in Wyoming," according to the study. "Magnitude of losses vary from one field to another, but impacts are universally negative and typically severe."

Deadly disease outbreaks

Even if energy development is limited and grouse habitat restored, it might not be enough to revive grouse populations in the basin.

The wild card in the equation is West Nile Virus -- a mosquito-borne disease that is lethal to the grouse.

One suspect is coalbed-methane operations in the region that hold billions of gallons of pumped groundwater in evaporation ponds. The ponds have long been suspected of serving as breeding grounds for mosquitoes that carry the disease.

The ponds are common with coalbed-methane operations because water must be pumped out of deep coal seams to coax methane gas to the surface, where it can be collected. Sage grouse are particularly susceptible to infection because during the hot, dry summer months, they gather around standing water where mosquitos are most abundant, exposing themselves to disease-transmitting bites.

Two large West Nile outbreaks in 2003 and 2007 wiped out entire breeding grounds, according to the study, and another similarly sized outbreak could slash populations in area leks by another 60 percent.

"Eliminating mosquito breeding habitat from anthropogenic water sources is crucial for reducing impacts" of West Nile outbreaks, according to the study.

Naugle, the University of Montana biologist, said that might not be possible because of the hundreds of ponds spread out over thousands of acres, and the fact that effective chemical treatments are very expensive on such a large scale.

In addition, many of the ponds are located on private land.

But the stakes are high.

"Incorporating outbreaks into analyses suggests that even with no additional energy development many local populations may be one bad [West Nile] year away" from extinction, according to the study.

Click here to read the study.

Streater writes from Colorado Springs, Colo.