Claremont homeowners file lawsuit one year after water began mysteriously seeping out of the ground

CLAREMONT, Calif. (KABC) -- One year ago, it was a mystery: why was water seeping out of the ground into more than a dozen backyards in Claremont?

At least one of those homeowners said it's cost her more than $30,000 to mitigate the water damage over the past year, to say nothing about what it's going to cost to repair any undiscovered damage.

Now, many of those homeowners have filed a lawsuit, alleging negligence on the part of the entities responsible for operating and maintaining groundwater recharge basins above their homes.

"We've got cracking, settling, and all kinds of issues," said homeowner Anet Larsen about some of the damage they've endured so far. "We're just trying to address the concerns we can address because it's going to take a lot of money."

Larsen said they first discovered the problem on Easter Sunday last year. After weeks of steady - and at times - heavy rainfall, the ground had become so saturated that water was seeping up and out of their grass, leaking through retaining walls, and even coming through tiles around their pool.

At first, they thought it was a leaking sprinkler valve or broken water main. But she said their water meter wasn't showing that any water was being used.

They later discovered that it was happening to other homeowners as well.

"(Our neighbor's) backyard was all overflowing with water. His pool was overflowing; it was algae, green," Larsen said.

Larsen said they believe that despite the record rainfall last year, the operators of the recharge basins above their homes continued to allow water to flow into the basins, instead of diverting that overflow toward a flood control channel.

According to the lawsuit filed against several cities, as well as the Pomona Valley Protective Association and the Six Basins Watermaster, the operators of several underground water recharge basins "continued to recharge the Spreading Grounds and neglected to adjust their operations to divert water away..."

Video provided to Eyewitness News shot in April 2023 appeared to show one of the basins overflowing, all the water rushing downhill toward the neighborhood.

"I mean this is our livelihood," Larsen said. "I've talked to so many neighbors. We've worked so hard to be where we are today."

Eyewitness News has reached out to several of the parties named as defendants for comment.