A moving wall of water following a severe thunderstorm Aug. 10 forced residents and tourists in a Havasupai Indian village outside Grand Canyon National Park to evacuate. Two days later, thunderstorms southeast of Page, Ariz., near Glen Canyon Dam, pushed a flash flood down a slot canyon, where it drowned 11 hikers.


"It was chocolate mud roaring down into this little 10-foot narrow canyon," an observer told the Arizona Republic.


The events topped off a disastrous August in Arizona, where thunderstorms mixed with seasonal monsoon winds from the Gulf of Mexico. On Aug. 6, a flash flood killed six Mexicans attempting to cross the U.S.-Mexican border near Douglas, Ariz. On Aug. 9, another flash flood damaged a bridge near Kingman and derailed an Amtrak train, injuring more than 100 people.


What hit Supai, a Havasupai Indian village at the confluence of Cataract and Havasu canyons, was a severe thunderstorm that National Weather Service radar detected at 9:30 a.m.


"Our guy called the Supai police (at 9:45 a.m.) and they reported heavy rain," said Weather Service spokesman Chris Cuoco. "Within about 15 to 20 minutes, the police called back and reported that flooding had begun." Rain over the previous three days had saturated soil so when rain hit that morning, it rushed downstream.


Rescuers, using Army National Guard and AirWest helicopters, took two days to evacuate 250 villagers, as well as some 300 tourists who had been staying in campgrounds near Supai. Damage is estimated at $500,000 or more.


*Peter Chilson