Thousands of fish were killed when a wall of water swept through the Cherokee Fish Hatchery.

The flash flood washed many of the young trout out of the raceways where they were being raised as well as taking down about 75 feet of fence surrounding the facility, hatchery supervisor Doug Reed said.

The hatchery has about 800,000 fish at any one time. Reed said Saturday he and other workers were still trying to determine how many had been killed as they cleaned up the mess. He estimated the damage at about $30,000-$50,000.

"It overflowed the raceways and poured the fish out onto the ground," he said. "It washed leaves and sticks into the raceways."

The flooding, produced by a cloudburst upstream in Great Smoky Mountains National Park, struck around midnight Thursday. Reed, who lives on the property, said he was in bed when it hit.

"All I heard was a big boom and the rocks hitting together," he said. "I jumped out of bed. It was kind of scary.

"The wall of water was about 8 to 10 feet high. It came down the road. It lasted about two hours before it started dropping a significant amount."

The hatchery, located off Big Cove Road on the Cherokee Indian Reservation, hatches the eggs of several species of trout, growing them to about a pound each. Then they are stocked in about 30 miles of streams and three ponds on the reservation. The hatchery produces about 35,000 pounds of fish a month.

Reed said he can't remember flooding that severe at the hatchery since the mid-1990s.

"It came down all at once."