Virus attacks in the Grand Canyon
Investigators traced the Norwalk outbreak to the Bureau of Reclamation’s sewage plant inside Glen Canyon Dam, which treats waste from the visitor’s center and power plant. Rather than using chlorine, which could kill fish below the dam, the plant uses ultraviolet light. But “viruses are more resistant than other organisms to UV light,” says Dr. Dennis Juranek, senior scientist at the Centers for Disease Control and Prevention.
Rafters treat their drinking water with chlorine, but they can’t use enough to kill the hardy virus without making the water undrinkable. Chuck Higgins, a public health consultant, will work with raft guides to develop better filtering procedures. Next season, he says, rafters may have to increase the dosage of chlorine and then use charcoal filters to remove the chlorine taste.
As for the sick rafters, “it sure wasn’t a comfortable time,” says river guide Mike Denoyer. “But it cleared up and people were able to enjoy the rest of their trip.”
Barry Wirth of the Bureau of Reclamation empathizes. “Being sick (with the Norwalk virus) in your home with your toilet and bottle of aspirin is one thing, but if you’re on a sandbar and half of your (rafting) group and the guide is sick, it’s a whole other situation.”