For most of us in Wyoming, mosquitoes used to be little more than a summer annoyance. We cared more about their impact on our enjoyment of the outdoors than on our health. In 1999, when West Nile virus was reported for the first time in North America, that all changed. Suddenly that harmless little whine of a mosquito outside the netting of your tent was more than something that kept you awake at night. It was the sound of an insect that could carry a potentially deadly disease.

Five years later, the disease has spread across the nation. Human cases have been reported in all states except Alaska, Hawaii, Maine, Washington, and Oregon. In 2003, Wyoming had the fifth highest incidence of West Nile virus in humans in the country with 375 documented cases and nine deaths. West Nile virus usually warrants respect rather than extreme alarm for most people. Eighty percent of those infected develop no symptoms, while the majority of the rest experience only mild problems. One in 150 people—usually individuals over 50 or with immune-system disorders—develop serious, life-threatening illnesses including meningitis or encephalitis. However, reducing exposure by using insect repellant and wearing long-sleeved shirts and pants or mosquito netting can minimize the risk of disease for most of us. For wildlife, the story is different.

Research focus shifting to West Nile’s impact on wildlife
"For the past four years, since the appearance of the disease, we’ve looked at West Nile virus as a human/wildlife disease," Dr. Christopher Brand, a United States Geologic Service scientist said in a February, 2004 press release.

"While we continue working closely with the human health community," he continued, "we also recognize that the virus may be dramatically affecting wildlife, especially wild bird populations and that we need to focus additional research efforts on wildlife impacts."

Birds—particularly members of the corvid or crow family—have been the heaviest hit by West Nile virus, although the disease has been documented in 29 mammal species and one reptile as well. Horses and burros can also die from the illness, but a vaccine seems to be helping to reduce their rates of mortality. "The rate of new [West Nile virus] infections in horses has gone downhill since the inception of the vaccine in 2002," Dr. Lanier Hamilton, DVM, of Lander said in a phone interview. "At the same time the rate of human cases continues to go up."

Birds are suffering huge losses from the disease. Some scientists worry that West Nile virus could cause long-term effects—even local extirpation—on certain avian populations.

Sage grouse, coalbed methane and West Nile
One of the populations that is causing concern in Wyoming is the sage grouse. Already threatened by dwindling habitat throughout the West, the sage grouse appears to be vulnerable to the West Nile virus as well. Preliminary evidence accumulated in 2003 indicates that there may be a link between the increase in sage grouse mortality from West Nile virus and coalbed methane development in the northeastern corner of the state.

"The level of West Nile virus mortality in sage grouse is very high in areas with coalbed methane production and low to almost nonexistent in places without," says Erik Molvar of Biodiversity Conservation Alliance, one of WOC’s frequent conservation partners. "The links are not proven yet…but the evidence is looking pretty strong that CBM development is increasing the rates of West Nile virus in sage grouse," he says.

In 2003, 19 sage grouse were reported dying from West Nile virus in Wyoming. Thirteen of these deaths were in Campbell County in areas with active coalbed methane development. Campbell County was also a hotspot for West Nile Virus among humans last year with 71 documented cases.

People like Molvar theorize the reason for Campbell County’s high incidence of West Nile virus is that pits created to hold coalbed methane-produced waters are turning into mosquito-breeding grounds. Grouse are attracted to these wet areas for their forbs and insects, and as a result are exposed to greater numbers of mosquitoes that are potential vectors for the virus.

"You have to put two and two together, but it seems pretty obvious that the standing water from coalbed methane production is creating mosquito breeding grounds," Molvar says. "Mosquitoes breed in late summer when water is scarce up in the [Powder River] Basin. There’s not a lot of irrigation going on in that area at that time of year. The only source of standing water is coalbed methane ponds."

Studies to explore effect of disease on sage grouse
The Wyoming Game and Fish Department is more reluctant to link coalbed methane development to sage grouse mortality from West Nile virus at this point, but its website documents evidence that seems to add force to the argument.

How Much Water Is There?
The final Powder River CBM EIS estimated that approximately 4,000 reservoirs would need to be constructed in the project area to hold all the water produced by CBM development. Since 2000, 2,545 applications for reservoir permits have been received. Currently there are 12,000 producing CBM wells in the basin. These wells pump water at an average rate of three gallons per minute. This means that roughly 17,280,000 gallons of water are being brought to the surface every day in the Powder River Basin.

According to information posted online, the Game and Fish Department determined that the major cause of sage grouse mortality at a coalbed methane site near Spotted Horse, Wyoming, was West Nile virus. At that site, six of eight adult hens died from the virus in a two-week period beginning at the end of July and stretching into early August 2003. Among 42 radio-collared hens monitored during the same period at two sites without coalbed methane development, only one case of West Nile virus was found.

Currently, studies by scientists from both the University of Wyoming and the University of Montana are planned for the 2004 field season to explore the effect of West Nile virus on sage grouse and to look into its possible link to coalbed methane development.

The University of Montana’s research under the guidance of Dr. David Naugle compares a control site in Montana with no coalbed methane development to a fully developed coalbed methane site in Wyoming and a third site where coalbed methane development is just beginning.

The University of Wyoming’s researchers will be looking into the direct impacts of the virus on sage grouse in the laboratory. They will study how the grouse react physiologically to West Nile virus and explore whether increased exposure is leading to the development of any resistance.

Biodiversity Conservation Alliance and the America Lands Alliance, represented by the Western Environmental Law Center, filed an amendment to their lawsuit challenging the Bureau of Land Management’s Environmental Impact Statement for coalbed methane development in the Powder River Basin in February asking to add the relationship between coalbed methane, West Nile virus, and impacts to humans and sage grouse to their original case. The amendment was denied, but Molvar says he expects BCA will continue to follow the research closely to determine if coalbed methane is causing irreparable harm to sage grouse, as he currently believes it is.

CBM operators are watching these developments warily. According to a report in the Casper Star-Tribune in early June, they are concerned that if a link between West Nile virus, CBM and sage grouse mortality is proved, it will add yet another expensive hurdle to their operations. Some have already voluntarily put larvacide for mosquitoes in their containment reservoirs.

WOC is monitoring the evidence and studies on the correlation between West Nile virus and CBM reservoirs closely. In addition, the spread of the disease has a cascading number of environmental consequences that cause concern. Communities across the state have increased their mosquito-control programs which include, among other things, more spraying of insecticides. The use of insecticides can have negative impacts on other insects, as well as the animals and birds that prey on them. Effects on humans are also potentially detrimental. Most weed and pest districts dismiss these effects, but it’s another issue that warrants attention.

In the meantime, Wyoming’s first human case of West Nile was reported three weeks earlier than last year. A man was confirmed to have the virus in early June. His was the third official case of the disease in the country, and he lives in Campbell County.