CARNATION, Wash. — Seattle Public Utilities (SPU) revealed the cause of the latest false alarm of the Tolt River Dam's emergency system Wednesday.
According to SPU, the unplanned siren on March 27 was accidentally triggered during remote work on the system.
The siren caused many residents in nearby Carnation to evacuate their homes. Residents thought they were preparing for a dam failure that would cause "catastrophic damage" to their community.
The Tolt River Dam holds back nearly 58,000 acre-feet of water, which provides as much as 40% of the City of Seattle's drinking water.
A second siren signaling the all-clear was sounded 20 minutes later.
SPU owns the Tolt River Dam and says an employee of one of its vendors, Federal Signal, "failed to follow procedures by not turning off siren communications while performing the planned work."
SPU said it has increased daily inspections since the incident. It also said the King County Office of Emergency Management would automatically send a message to every cellphone in the impacted area if there is a dam emergency so people can be certain it is not a false alarm.
Last week, Carnation city leaders said they plan to sue SPU after eight false alarms have been sounded in the past four years. According to the city, only one other incident has been explained, and that was also caused by human error.
Meanwhile, the City of Carnation is calling for the emergency alert system to be shut down entirely.
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