Boulder artist David Grojean said his studio was flooded under 5 inches of water. "My artwork is all around," said the painter, 65. "I had to get paintings off the ground and onto tables. Some got wet. None seem to be destroyed. But it's still raining."

TV news reported foothill residents stranded in trees and huddled on rooftops, with emergency workers unable to reach them. There were reports of 8-foot debris walls with more than 6 feet of water behind them. Yet a few hardy souls stood in the rain, filling bottles with silt and, they hoped, gold.

The once-tranquil creek that snakes through Boulder resembled the Mississippi River. Boulder Creek flowed at 1,800 cubic feet per second, nearly 10 times its usual 200 feet per second, said Sarah Huntley, a spokeswoman for the city. Overnight, it was roaring at 3,200 cubic feet per second.

The creek flooded a recreation area with rushing rapids that overturned picnic tables, submerged small trees and bushes and approached the bottom of the park's volleyball nets.

"We're dealing with a disaster that is broad in scope and damage," Boulder County Sheriff Joe Pelle told reporters. "We are likely to find more victims. We're bracing for the worst."

Bronson Hilliard, a spokesman for the University of Colorado-Boulder, said 351 graduate students and staff members were evacuated overnight from graduate and family housing apartments on campus adjacent to Boulder Creek. An additional 13 underclassmen were evacuated from two other residence halls.

The university was closed Thursday and will remain shut Friday. Students living on campus were urged to stay in their dorm rooms.

And the rain kept falling, the rushing water given free passage across forestland scarred by recent wildfires.

A somber Sheriff Pelle voiced trepidation about Friday.

"It doesn't look very good," he said of the storm. "It's far from over."

john.glionna@latimes.com

Deam, a special correspondent, reported from Boulder. Glionna reported from Las Vegas. Michael Muskal in Los Angeles contributed to this report.