Water release from San Antonio Dam causes flooding in Stone Canyon neighborhood of Claremont

CLAREMONT, Calif. (KABC) -- What began as a mysterious water leak in Claremont turned into full-on flooding Wednesday night after water was released from the San Antonio Dam.

In a letter from the city of Claremont sent to residents on Tuesday, city staff was initially notified of "abnormal groundwater seepage" in the Appalachian and Nashotah areas of the Stone Canyon development. A few days later, the city began getting calls about more groundwater seepage from homeowners on New Hampshire and Moody Place.

"In response, staff was informed that the Six Basins Water Master is conducting spreading operations to recharge the groundwater levels from what appears to be water released from the San Antonio Dam," read the letter. "Army Corps of Engineers records for the San Antonio Dam show a water level decrease of 20 feet within the last 15 days."

The Pomona Valley Protective Association has since been trying to divert water away from the Stone Canyon area.

Meanwhile, homeowners told ABC7 on Wednesday they have counted at least 27 homes that have been impacted.

"We started gathering pumps, we started digging holes to create sumps for the water to go down into," said Claremont resident Ken Larson. "That first day started with two pumps and currently today, I have seven pumps running to keep the water."

Many residents called for extra help to salvage their backyards.

"Hundreds of millions of gallons of water at one time in a very short period of time, so it's all coming down the watershed, going through the soil, none of it above ground, it's all below ground and that's the scary part," said Claremont resident Vikas Mehta. "We called our friend who is a contractor and he's like, 'Oh, you need industrial sized, you know, commercial equipment because this is a million gallons a day you're getting here."

The city says it will be delivering sand and sandbags to Padua Park to help homeowners in creating water barriers around their homes.

Building inspectors and staff are available to inspect homes and foundations, the city said.

If homeowners see any cracks or signs of damage on their home, they're urged to contact the Claremont's City Building Division at 909-399-5471.