SIMI VALLEY — A 66-inch water main collapsed Saturday, closing a portion of Madera Road in Simi Valley and causing water damage to at least one dwelling, officials said.
The break in the Calleguas Municipal Water District main occurred about 5 p.m. beneath the two southbound lanes of Madera Road north of Royal Avenue, flooding the street and nearby parking lots with 2 to 3 feet of water, said spokeswoman Kerri LeClair of Simi Valley Water District.
As a precaution, officials asked 50 people to leave their homes or businesses after the break, but by late Saturday night all but the inhabitants of the damaged dwelling were allowed to return. No injuries were reported.
Water was shut off in spots throughout the Simi Valley district, but LeClair did not know how many customers were affected.
Madera Road was littered with 3-foot chunks of asphalt that had been thrust up by the pressure of the water, which was not shut off until 6:34 p.m. A sink hole caused by the break measured 30 feet long, 12 feet wide and 6 feet deep, said Ventura County Fire Department spokesman O.J. Hunt.
"There was a lot of water just gushing out of a large hole," said 40-year-old David Hammon, who lives on nearby Vaquero Drive. "I saw a rupture and huge chunks of asphalt pushed up."
The hole kept the southbound lanes of Madera Road closed Saturday night between Los Angeles and Royal avenues, and officials said only local traffic would be allowed in the area through Monday. Officials had no dollar estimate Saturday night on damage to the road.
Water pressure in Moorpark dropped due to the broken main, and the Oxnard water district was forced to shut off its connection to the Calleguas line, officials said. Oxnard blends the Calleguas water with local ground water.
As crews worked late into the night to repair the damage, officials from the Calleguas water district were trying to figure out what caused the 4-inch-thick cement and steel pipe to collapse.
Calleguas district manager Donald Kendall said a power outage could have caused the break. The outage shut off water pumps on Erringer Road in Simi Valley, lowering the pressure inside the water main and possibly causing the collapse, he said.
Officials were also investigating whether an incident Wednesday could have contributed to the break. The pipe had been shut down Wednesday for three days after it was damaged by a contractor at Wood Ranch about a mile south of Saturday's break, said Kendall.
On Saturday, the line was being tapped heavily by its 20 municipal water suppliers, due to increased demand by their residential and business customers, Kendall said.
Late in the evening, LeClair could not say how many residences in Simi Valley had lost water service due to the incident. Because the pipe was a transfer main, there were no reported outages in the immediate area after the break.
Witnesses said the area near Madera Road and Royal Avenue looked more suitable for boats than cars right after the rupture.
"It was like a river, and we just tried to move the car because we were afraid the water would gush up onto it and flood the floor of the house," said 26-year-old Jose Contreras, who lives in the Shadowridge Apartments on Ridgegate Lane. "But thank God, nothing happened.
"It was coming from Madera Road," he said. "We could see from the balcony how the water was running like a river."
Red Cross emergency services director Richard Rink said volunteers were sent to the area and offered assistance to two families, but both declined.
"We let people know we're available and if they change their minds, we will be there if they need us," he said.
Times staff writer Carlos V. Lozano contributed to this report.