NewsTeam 10 Investigates


Team 10: Leak in a San Diego reservoir known for more than 25 years

Report shows leak known since '94
Posted at 2:33 PM, Apr 18, 2019
and last updated 2019-04-18 21:28:58-04

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SAN CARLOS (KGTV) - Some neighbors in the San Carlos community are wondering what is being done about a reservoir that has a leak dating back to the 1990s.

The San Carlos Reservoir by Wing Span Drive and Tommy Street was built in the 1990s and can hold up to 5 million gallons. According to a 2014 analysis on the reservoir by an outside engineering firm, there were issues with the reservoir more than 25 years ago.

“In 1994, the San Carlos reservoir had already experienced leakage at several locations at the bottom of concrete wall/pavement area. Per the original construction, a gap was left between the floor slab and wall for a filler material. The filler material appeared to have deteriorated, which may have allowed for leakage,” the 2014 report by Kleinfelder/Simon Wong Engineering stated.


A city spokesperson told Team 10 the reservoir went back into service because it is needed for water pressure for fire protection. They would not provide an on-camera interview, but a spokesperson said it was a “minor leak of about .2 gallon per minute.”

With the numbers the city gave Team 10, more than 105,000 gallons per year is going down the drain.

“It’s concerning because we’re supposed to be conserving water, for one thing,” said neighbor Tom Lincoln.

City officials tried to fix the problem. According to emails to Team 10 from city public information office Arian Collins, the reservoir was taken out of service and drained in 2002 to install a liner. “The second liner installation started in 2010 and ended in 2014. There was no water in the tank between these projects,” the email stated.

“I wish they’d figure something out. We certainly pay enough taxes,” added neighbor Gerry Plotkin.

The waste may have been larger years prior. 2016 was the latest effort to stop the leak by replacing a liner in the reservoir. The Capital Improvement Project, according to the city, cost roughly $750,000. The spokesperson said while it “helped reduce the leakage partially, it was not successful” in completely stopping it. When Team 10 asked how much the reservoir was leaking prior to 2016, the city said they had “no data.”

Councilman Scott Sherman’s district includes San Carlos. He confirmed work on a new pump station that will replace the San Carlos Reservoir hopefully within the next few months.

“Once that comes on, we’ll be able to take that tank down and be able to actually address the leak again,” Sherman said. “Hopefully they’ll get it right this time.”

The city then plans to rehabilitate the San Carlos Reservoir fully. That project is projected to be finished within five years.

“There are a lot of things that were put on the back burner awhile ago and we’ve been constantly playing this game of catch up and fixing the systems. Unfortunately, you do have to prioritize what needs to get fixed when,” Sherman said.

Water reservoirs can sometimes leak. American Water Works Association guidelines allow a small percentage per day.

“The Public Utilities Department is unable to determine compliance with the AWWA standards as there was no data before 2016.

“The AWWA standards can only be confirmed with the current estimated leakage amount of 0.2 gallons per minute, which is less than the AWWA allowable percentage of 0.05 percent of total volume over a 24-hour period,” the city spokesperson wrote.

Whether or not the reservoir was in compliance years ago, the city does not know because there was no data before 2016.