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Flood warning system sounds false alarm

An early flood warning system for San Francisquito Creek brought online earlier this year sent out a false alert Wednesday morning.

The warning was sent around 9 a.m. Wednesday when an in-stream sensor indicated there was a large flow in Bear Creek despite the lack of rain, San Francisquito Creek Joint Powers Authority executive director Len Materman said.

Bear Creek is a major tributary to San Francisquito Creek, which runs through San Mateo and Santa Clara counties, Materman said.

A contractor employed by Stanford University worked on the sensor the day before and somehow led to the false reading on Wednesday, according to Materman.

The system, built this year and brought online in October, sends out notices if the sensors indicate a 60 percent chance of capacity near a flood-prone bridge within the next two hours, Materman said.

The four flood-prone bridges are in Menlo Park and Palo Alto along the creek at U.S. Highway 101, University Avenue, Middlefield Road and Pope and Chaucer streets.

Any flood watches or warnings are sent to the system’s subscribers by text message or email and posted on the system’s website at

It was “unfortunate” the false warning was sent out on the system, which the agency constantly tests and improves in preparation for major rain, Materman said.

Changes have been made to the sensor to make sure there are no future inconsistent readings, according to Materman.

To address Wednesday’s mishap, the agency will send a person to check on the creek if the system indicates there is chance for a flood, Materman said.

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