YAKIMA -- Fourteen years ago, a pneumonia outbreak among bighorn sheep in Hells Canyon along the Snake River killed about 300 of the animals, leaving a scene one scientist called "like a war zone ... sheep lying dead everywhere you looked."
Wildlife experts are urgently working to prevent that from happening again in the Yakima River Canyon.
Since the first week of December, about 10 bighorns on the west side of the canyon have died from pneumonia and dozens more have become infected.
State wildlife officials are hurriedly developing a strategy to prevent the disease from wiping out not only the 150 or so bighorns on the ridges west of the canyon, but neighboring herds across the Yakima River (roughly 100 animals), on Cleman Mountain (about 200) and in the Tieton area (also about 200).
Because the outbreak is so contagious and fatal, the idea of killing the herd is quickly moving from possible to inevitable -- which would mark the first time the state has tried to control an epidemic among bighorns by killing large numbers.
"We're trying to get a good sense of how widespread the outbreak we have now is, and whether there's anything practical we can do to contain it," said Jeff Tayer, regional director of the Washington Department of Fish and Wildlife. "We wouldn't hesitate to eliminate parts of this herd to save the rest if we thought that was practical and would work."
The department first began receiving reports of dead bighorns west of the canyon and north of Umtanum Creek around Dec. 4. Several of the carcasses were taken for testing at Washington State University veterinary laboratories, and a few other bighorns from different herds were collected, killed and then examined to assess the disease's spread.
Over the past three weeks, wildlife biologists have been flown by helicopter into areas near bighorn groups, where they looked for sheep that were coughing, indicating possible pneumonia.
Most of the bighorns north of Umtanum Creek are believed to be infected. The sickness is less prevalent among bighorns south of the creek, though the number of sick animals is growing there as well, according to fish and wildlife biologist Jeff Bernatowicz. None of the bighorns east of the Yakima River is believed to be infected, he said.
Officials don't know how the pneumonia was introduced to the bighorns. Domestic sheep and goats carry parasitic pathogens that are benign to them but can be deadly to wild animals like bighorns. And there are small, sparse numbers of domestic sheep in the Wenas area and in the Kittitas Valley, as well as grazing allotments on Forest Service lands to the west.
The state fish and wildlife department has given itself until mid-January to make a decision on what steps to take.
For the winter months, officials aren't concerned of intermingling between the different herds. But in March and April, the ewes begin to move around more in search of a safe place to have their lambs, and by summer the bighorns readily cross the Yakima River, where they could come into contact with the herd on the east side. And by the mating season in early fall, rams will be crossing the river in large numbers in search of fertile ewes, Bernatowicz said.
"If those animals (east of the Yakima River) get infected," he said, "then you have lots of potential for them even getting into the Quilomene." There are roughly 150 bighorns total in the Quilomene, Whisky Dick and Colockum areas.
But because of the temporary remoteness -- and de facto quarantine -- of the Yakima Canyon's west-side herd, officials believe removing the entire herd would prevent a worse epidemic later.
Possibilities include having them killed by federal USDA Wildlife Services, by local state wildlife biologists or even issuing permits for hunters -- who would certainly line up in droves and be willing to bid top dollar for the chance.
A public health problem related to the bighorns' pneumonia, though, would not be a deterrent to a permitted-hunting option. The meat of the bighorns isn't affected, and the bacteria that causes the pneumonia, Bernatowicz said, "doesn't affect humans at all."