A computer malfunction sent tens of thousands of gallons of water, mud, rocks, and debris rushing through a Cedar Hills neighborhood on Saturday morning.

Around 9:30 a.m., flood water streamed from a city water tank located on the mountainside overlooking the city, traveling all the way down to and along Canyon Road. For a few panicked moments it may have seemed like the Cedar Hills landslide of 2005 all over again, but this time the results were much better. The only significant damage was to the yard of one home, where the front and back lawns and the driveway were covered with rocks and muddy debris. The interior was unharmed, and city crews and neighbors were working to clean up the mess outside.

On April 28, 2005, a landslide forced four Cedar Hills families to permanently abandon their townhomes. The toe of the 375-feet long, 150-feet wide slide piled up against the townhomes, which have since been demolished. Saturday's flood was perhaps 200 yards away from the 2005 flood.

The sudden rush of water on Saturday was believed to have been caused by a brief electrical storm late Friday, causing the computer monitoring system on a city irrigation water tank to malfunction, said residents who had been briefed by city staff. "The computer failed and caused the overflow," said Kerry Nielsen, manager of the home, which is a rental property owned by a California couple.

Pumps on the city's water tank, producing 7,000 gallons of water a minute, failed to shut down when the tank was full, said Shawn Stratton, who until two weeks ago had lived in the townhome that took the brunt of the water.

The electronic equipment used by the city to monitor the tank gave "a false reading when in fact the tank was full," said Councilman Eric Richardson, who toured the flood area around noon. The city had built in a flood channel, knowing a failure of this kind was possible. The flood channel had a clog, which caused the water to divert onto the lawn and driveway of the residential home affected.

It wasn't immediately clear whether the culinary or irrigation water tank flooded, Richardson said. Both tanks are located in the area, and the culinary tank is designed to overtop into the irrigation tank in the event of excess water. Richardson said it was possible that 7,000 gallons a minute was being pumped in the flood because the pumps have that capacity, but it will take time for the city to verify all the details of what actually happened.

"It was certainly a lot of water," he said.

As far as clean up, the city is working on it, he said.

"Are we going to do the right thing?" Richardson said, noting the damage is minimal. "Of course we are."

There was a bit of comic relief on Saturday. The new renters of the townhome were believed to be away from home at the time of the flood. Neighbors and Nielsen spent nearly two hours trying to get into the locked home to access whether the water had flooded the house. Unable to reach the renters by phone or at the property, a locksmith was called to open the house, but just before the locksmith arrived -- and nearly two hours after the flood started -- renter Sheri Davis opened the front door to ask what was going on, much to the astonishment of everyone who had been working to clean the yard, driveway and street.

"What happened? We just barely saw this," Davis said, stepping out onto her front porch, taking in the mud and rocks that now covered her lawn. Davis said she had just recently noticed the commotion outside, but hadn't realized that her home was at the center of the action.

"Apparently the world was falling apart and I didn't know," she said, noting she had been on the computer in an isolated room while other family members had been sleeping.

"Your driveway was full of rocks," Nielsen told her, as city crews continued using a bulldozer to remove rocks and mud from the street feet away from the family's front door.