If Wyoming's findings are true, and at this point it appears they are, it can be assumed that someday whirling disease will reach Flaming Gorge and then the lower Green River.
The question is when? It could be years and it could be decades."We simply don't know," said Chris Wilson, a biologist with the Utah Division of Wildlife Resources' fish experiment station in Logan.
In July, the Wyoming Fish and Game discovered whirling disease spores in fish in a small irrigation canal leading off the Green River called Forty Rod Creek.
Further tests have confirmed the presence of the disease, said Dave Money, fish pathologist with the WFG.
"How it got there we simply don't know. There's no reason for it to be there. It's a little irrigation canal that comes off the Green River, goes by one of our hatcheries, then feeds back into the Green. We discovered it on a routine test," he said. Spores were found in both brown and rainbow trout.
The creek is located above Pinedale and about 100 miles from the northern tip of Flaming Gorge.
So far, said Money, there have been no positive findings in either the hatchery or the Green River, "but we're continuing to test."
The disease is spread by a small spore that is eaten by a T-tubifex worm, which is then eaten by fish. Rainbow trout and kokanee salmon are most susceptible to the disease, which attacks the cartilage development in young fish and causes deformities, can eventually result in premature death. When the fish dies, the spore is released back into the water to be spread to other fish.
What has Utah biologist concerned is that the fish most vulnerable, the rainbow and kokanee, are the important fish in the Gorge. The situation is complicated even more by the life cycle of the kokanee. That is, the kokanee move into tributaries to spawn in great numbers, and after they spawn they die.
"This has the potential for a large release of the parasite into the drainage. It has been a concern at Porcupine (Reservoir). Seventy percent of the spawning kokanee there carry the whirling disease parasite, and the number of deformities there continues to rise each year," Wilson said.
The kokanee, too, is a major food source for the trophy-size lake trout for which Flaming Gorge has become noted.
Whether whirling disease will ever get into the Green River or make it to Flaming Gorge is at this point purely speculation.
It has been found, for example, that obstacles in the river, such as reservoirs, can halt the movement of the parasite.
"We've had the disease in Otter Creek for some time now, but we've never found it in the Sevier River below. We hope that will be the case here," Wilson added.
About 40 miles downriver from the infected canal is Fontenelle Reservoir. And, if it ever did reach Flaming Gorge, then it too could be a major barrier stopping the disease from reaching the Green River.
Wyoming first discovered whirling disease in a drainage near its border with Colorado in 1988. Currently it is found in five drainages in Wyoming. All of the drainages in Colorado are now infected with the disease.
The first infection in Utah was found in a private hatchery near Loa in 1991. It is currently found in isolated places in Utah, mainly in northern Utah, around the Loa region and most recently in the upper Provo above Deer Creek.
Money said Wyoming officials are not in a panic at this point but are optimistic that it can be contained.
"In the areas where we've found whirling disease, we are seeing it in very low levels. It has not dramatically effected the fish. Outfitters and fishermen say that the fishing is still very good in those areas," he added.
Wilson pointed out that studies are currently under way to help determine why the disease infects some waters more than others. In the Madison River in Montana, for example, 90 percent of the population of rainbow trout have been wiped out by the disease. In other infected waters,the losses are much lower.
Most of the rainbow in Flaming Gorge are the larger fish planted there each year and are not vulnerable to whirling disease. The kokanee, on the other hand, spawn and as small fish are very susceptible.