Alerting system for possible San Mateo County dam failure ‘deliberately redundant’

The reservoir and dam are operated, maintained and observed by the SFPUC, which employs precise instrumentation to keep an eye on its structure on a constant basis, Rhodes said.

The dam’s integrity is easily defended by its survival of the 1908 and 1989 major earthquakes, Rhodes said, but SFPUC would know if anything was of concern with plenty of time to warn its partner agencies, and subsequently, residents.

“Because we use all these tools, our crews would be forewarned of any conditions to the dam that would warrant further inspection and might say that the dam’s integrity is compromised,” Rhodes said.

SFPUC does not have alerting authority, but they will send appropriate notifications to all partner response agencies, and individual cities can issue alerts within their jurisdiction.

In addition to the county’s emergency alert system operated by the Department of Emergency Management, the county’s Sheriff’s Office, CalOES and the National Weather Service all have the authority to issue wireless emergency alerts to the public, Dr. Shruti Dhapodkar, director of the Department of Emergency Management, said.

The Department of Emergency Management’s alerts are often supplemental to other information provided by other agencies, Dhapodkar said. The department also has the ability to activate the Emergency Alert System, which broadcasts information over television and radio.

“This multiagency, multichannel approach ensures that the public receives timely alerts through several independent systems, minimizing the risk of a single point of failure,” Dhapodkar said.

The communication was put to the test during the heavy rains during 2022 and 2023, which resulted in reservoir levels getting close to spillway, Rhodes said. Although SFPUC is not a flood control district, they communicated with regional partners — including those monitoring the San Mateo Creek — that levels were rising, preparing them for the possibility of local flooding.

“We could see this coming, so we initiated our emergency action plan for the county,” Rhodes said, which includes direct contact information to equip everyone with the necessary information.

Local authorities then used this information to decide when they would communicate with residents, Rhodes said. Though an evacuation order wasn’t sent out, local alerting systems told residents to be wary of creek water levels.

“If residents do one thing, sign up for alerts,” Rhodes said.

San Mateo County residents can opt in to receive emergency alerts by text. Visit www.smcgov.org/dem/smc-alert for more information on how to sign up.