The incident happened around 11:15 a.m. local time when the failure alarm at the Tolt Dam, a 200-foot high earth-filled dam, began going off in the city of Carnation, located about 30 miles east of Seattle.
The Tolt Reservoir and Dam are located 16 miles upstream from Carnation along the South Fork Told River, and supply about 30 percent of the drinking water for 1.3 million people in the Seattle area, according to the Seattle Public Utilities (SPU).
Interim Carnation City Manager Bob Jean told KING5 he thought the alarm was “believable” and “very real,” while trying to get more information from SPU.
“We started going through our notifications, and evacuation process,” he said.
According to the SPU website, pre-recorded sirens will play during a local emergency in the event of a dam failure when high water in Carnation “may exceed a depth of 13 feet within a short period of time.”
“In the unlikely event of a dam failure, water from the reservoir may inundate the City of Carnation,” the utility states. “To alert residents of such an event, the city works closely with the local government to maintain an advanced dam failure warning system.”
If the dam were to fail, sirens will activate and the following message warning will go out to residents to evacuate the area: “The Tolt Dam has failed, evacuate the area immediately.”
Jean told KING5 that SPU called Carnation back after a few minutes, but the alarm and electronic voice warning to evacuate sounded for about an hour.
That sent people scurrying for safety.
One person told Q13 FOX that fire trucks and firefighters were initially telling people to evacuate before learning it was a false alarm.”
“A truck came through saying ‘The Tolt Dam has been breached. Get out! Get out! Get out! Get out!” another woman told Q13. “Then another woman came screaming at us and people that were in the river started running. So the word got out that the dam had collapsed.”
The quick rush to leave also caused a temporary traffic bottleneck in the area, local news outlet Living Snoqualmie reported.
The King County Sheriff’s Office had taken to Twitter to also alert the public, saying it was a “false alarm.”
“The Tolt Dam failure alarm in Carnation that was activated is a false alarm,” the sheriff’s office said. “The dam is safe, please disregard the alarm.”
Sgt. Ryan Abbott with the King County Sheriff’s Office confirmed to Q13 that the sirens sounded in error.
The warning system is tested every Wednesday at noon, when sirens are activated and pre-recorded audio messages are played, according to the utility.
Jean told KING5 the incident was a learning experience for the city, but that the community also stepped up.
“But I was pleased to see that most people in town took it seriously,” he said.