Seattle Public Utilities will fully activate the new Tolt Dam Warning System on Oct. 18, fully replacing the old system and – residents hope – ending a recent string of distressing false alarms.

The aged and outdated old system rang out for the last time during its regularly scheduled weekly test on Oct. 11. The following week, the dam will fully transitioned to a new “state-of-the-art” alert system, SPU said in a statement.

The warning system is designed to alert residents of failure on the Tolt Dam, a breakdown that would lead to catastrophic flooding in Carnation. Over the past three years, however, the system has experienced six false alarms, including three in recent months.

Officials with the city of Seattle, which owns the dam, say replacing the old system that was installed in 1993 will be the single most important step in preventing future false alarms.

“The vast majority of issues with false alarms have been due to the old system,” said Josh Campbell, project manager for the warning system update. “Simply put, it’s an outdated system that is difficult to maintain and has too many variables that can lead to a false alarm.”

During an August incident, for example, technicians were repairing an old siren antenna downtown when they accidentally pushed the siren button and triggered a false alarm. The input was canceled, but it was too late to cancel the siren command, Campbell said.

The new system is less prone to these mishaps, requiring the button be held for at least a second, Campbell said. The new system also allows for SPU staff to see almost in real time if there’s local activation of the siren.

SPU expects to continue working on the alert system and related infrastructure over the next year. Technicians will work to enhance the current alert system, install a series of new indoor and outdoor sirens, add electronic signage on the highway and fix evacuation signs.

The Carnation City Council declared a state of emergency over the dam’s false alarms in August and requested the Seattle City Council take action to address solutions of the dam.

The last ring out of the old system comes a little over a week after the city of Carnation held a community meeting at Tolt Middle School alongside state and federal leaders discussing the recent false alarms. The city estimated 200 people were in attendance.

In an interview, Carnation City Manager Ana Cortez said following the meeting the city is working alongside SPU to gather more information about the dam and its warning system. Cortez said they plan to continue discussions with Seattle officials, including things like penalties for false alarms and compensation for funds spent on mitigation measures.