Tolt Dam Early Warning System

Photo of Tolt river

This project will improve the resiliency and reliability of the Tolt Dam Early Warning System. 

July 29, 2024 Update

In consultation with the Carnation City Council, Seattle Public Utilities (SPU) is hiring a panel of independent, third-party experts to review the Tolt Dam Early Warning (siren) System and assist SPU with project decisions.

The panel is expected to be confirmed later this summer and their public report is expected in 2025. The Tolt Dam Early Warning System will remain turned off until the panel concludes their work. The panel’s primary tasks include:

  • Reviewing the current regulations as they pertain to dam safety, public alerting, and emergency response
  • Evaluating the past issues related to the Tolt Dam Early Warning System and the responses on the part of the City of Seattle
  • Developing recommendations and considerations for a path forward regarding the Tolt Dam Early Warning System
  • Summarizing their results in a non-technical public report

SPU continues to monitor the dam 24/7, 365 days a year. In the unlikely event of a dam emergency, notifications will be made using existing emergency notification systems including the Wireless Emergency Alert system, King County ALERT notifications, Reverse 911 phone calls, and weather radio notifications.

April 19, 2024 Update

Thank you to everyone who took the time to fill out our survey regarding your experiences of the unexpected siren sounds on March 27. The survey is now closed. The survey results will help us consider future actions regarding the siren system. Please note that the siren system remains turned off until further notice. We will communicate widely with the community before we take any future steps with the system, including reactivation.

If you have additional comments or questions, you can continue to contact us by emailing tews.info@seattle.gov or leaving a voicemail at (206) 494-5986 and we will return your call.

April 12, 2024 Update

The Tolt Dam remains safe. SPU monitors it 24/7, 365 days a year visually and with instrumentation and sensors.

Our robust dam safety program includes daily visual inspections and instrument readings by operators, dam safety quarterly inspections, federal annual inspections, and independent consultant inspections every 5 years.

Please note that SPU has cancelled the weekly Wednesday at noon siren test in Carnation until further notice while we continue to investigate the March 27 incident.

April 2, 2024 Update:

Seattle Public Utilities’ (SPU) investigation into the unplanned siren activation in Carnation on March 27, 2024, is ongoing.  To date, we have learned that one of our vendors, Federal Signal, accidentally caused the activation while doing remote work on the system. 

Federal Signal has said that one of their employees failed to follow procedures by not turning off siren communications while performing the planned work.  Federal Signal has apologized to SPU and asked us to convey their apology to the Carnation community.

As part of our investigation, SPU is asking anyone in the Carnation area who heard the unplanned siren on the morning of March 27  to contact us so we can gather some information. Please share what you heard: (206) 494-5986 or tews.info@seattle.gov.

The Tolt Dam remains safe. SPU monitors it 24/7, 365 days a year and following the March 27 unplanned sounding, we have increased daily inspections. Our robust dam safety program includes daily visual inspections and instrument readings by operators, dam safety quarterly inspections, federal annual inspections, and independent consultant inspections every 5 years.

Please note that SPU has cancelled the weekly noon siren test on April 3 in Carnation while we continue to investigate.

We have worked with King County Office of Emergency Management to ensure the community would be notified in the unlikely event of a dam emergency through the Wireless Emergency Alert (WEA) System. WEA would broadcast a safety message, similar to an Amber Alert, to all cell phones in the impacted area. No one needs to subscribe-these alerts are automatic.

March 29, 2024 update:

Yesterday SPU turned off the Tolt Dam Early Warning System sirens in Carnation while we investigate the cause of the unplanned siren sounding on March 27.

SPU has worked with King County Office of Emergency Management to ensure the community would be notified in the event of a dam emergency through Alert King County and the Wireless Emergency Alert System.

In addition, SPU is increasing daily inspections of the Tolt Dam and will continue its robust dam safety program which includes daily visual inspections and instrument readings by operators, dam safety quarterly inspections, periodic and annual evaluation and documentation of surveillance and monitoring, Federal Energy Regulatory Commission (FERC) annual inspections and independent consultant inspections every 5 years.

March 28, 2024 update:

Following Wednesday’s unplanned alarm/siren, Seattle Public Utilities (SPU) has been in frequent contact with Carnation officials, and we are aware and sympathetic to the frustration and concern expressed by residents and officials at last night’s City Council meeting and today’s news conference. 

SPU staff continue to investigate what happened yesterday morning. After residents and officials began reporting what they heard shortly after 10 am, SPU activated its emergency response plan with its emergency partners. We verified the dam was safe and immediately launched an investigation. We continue to monitor the dam 24/7 as we do 365 days a year.  

As part of our investigation, SPU is asking anyone in the Carnation area who heard the unexpected alarm/siren yesterday morning to contact us so we can gather some information: (206) 494-5986 or tews.info@seattle.gov.

SPU will not stop investigating until we determine what happened. We sincerely apologize for the confusion and worry following the event. 

March 27, 2024 update:

Seattle Public Utilities (SPU) is aware that the Tolt Dam Early Warning System unexpectedly sounded Wednesday, March 27, at 10 am.

SPU staff verified that the dam was and continues to be safe, and we continue to monitor the dam 24/7 as we do 365 days a year. We sincerely apologize for this incident and are still investigating the cause.

March 4, 2024 update:

Phase 1 of the new siren system is complete:

  • This phase included replacing all eight existing siren locations and adding three new outdoor siren locations for a total of 11 upgraded siren installations: 7 outdoor and 4 indoor
  • At the end of 2023, all the new outdoor sirens were upgraded with more powerful speakers, and the spoken voice was reprogrammed to increase clarity
  • In partnership with the City of Carnation, the new siren on Tolt River Rd NE and 334th Ave NE was relocated to the city’s Public Works yard about 1,000 feet west
  • The new system has been operational as of October 2023, and the three added outdoor locations were installed and activated in December 2023
  • The old system was turned off in October 2023 and will be dismantled and removed in 2024

Phase 2 activities and enhancements will continue in 2024:

  • Acoustic testing and installation of new static evacuation signs in the WSDOT right of way are expected in the coming weeks.
  • Two of the new outdoor siren locations are operational using solar power and batteries and will be connected to the PSE grid in the coming months
  • Highway message sign locations are in the process of being selected in partnership with the City of Carnation with installation expected in 2024

About highway message signs:

  • The purpose of highway message signs (HMS) is to alert drivers heading towards Carnation in the unlikely event of a dam break emergency and help direct them away from town. Placed strategically, they offer visual alerts to drivers heading toward Carnation.
  • HMS locations are being carefully considered to allow drivers time to turn around or use alternate routes at intersections or roundabouts
  • HMS convey a concise message during a dam break emergency, "DAM BREAK NO ENTRY." Under normal circumstances, the signs will remain turned off.

For the latest information about the project, please continue to check this website and subscribe to the project email list.  

Project description

The Tolt Dam Early Warning System alerts residents in the City of Carnation to evacuate in the unlikely event of a dam failure. The first emergency warning system for the Tolt Dam area was implemented in 1978 as a single siren controlled by King County. The City of Seattle took over responsibility for the siren system in 1981 and the first network improvement occurred in 1985. Additional improvements were made in 1993. The capital project will replace the aging system, now in its fifth generation and difficult to maintain, with state-of-the-art technology and equipment that will improve the resiliency, reliability, and security of the emergency warning system.

The project will:

  1. Replace, and improve outdated siren and supporting system components.
  2. Add redundancy, resiliency, and reliability where necessary.
  3. Address consistent evacuation procedures and protocols with additional signage.
  4. Listen and respond to community needs and suggestions.

Location

New outdoor sirens and indoor alerting devices have been installed at key locations within the inundation area. This included replacing sirens at existing sites and adding three new siren locations for sirens and additional highway messages signs.

Here are the locations where the 7 new outdoor sirens and the 4 new indoor sirens (annunciators) have been installed for phase one of the project:

  1. 35805 NE 80th St (replaced outdoor siren)
  2. 6921 Tolt River Rd NE (replaced outdoor siren)
  3. 5502 Tolt River Rd NE (replaced outdoor siren)
  4. 32421 E Entwistle St (replaced outdoor siren)
  5. Tolt MacDonald Park (new outdoor siren)
  6. Near the intersection of NE 60th St and SR 203 (new outdoor siren)
  7. Tolt Highlands Rd NE and Tolt River Road NE, City of Carnation Public Works yard (new outdoor siren)
  8. 4950 Tolt Ave –Elementary School (replaced indoor annunciator)
  9. 3740 Tolt Avenue –Middle School (replaced indoor annunciator)
  10. 3944 320th Ave NE – Bus Facility (replaced indoor annunciator)
  11. 3600 Tolt Ave – Fire Station (replaced indoor annunciator)

Community benefits

This project will improve the resiliency and reliability of the Tolt Early Warning System by upgrading it with state-of-the-art technology and equipment and adding more redundancy in the system. When the project is completed, stakeholders and residents in the Carnation area will have a new emergency warning system that better meets the needs and expectations of the community.

Community engagement and project materials

The project team provides bi-weekly updates to Carnation City officials, updates this website regularly, and sends informational emails to subscribers.

Please subscribe to the project email list to receive these updates.  

ALERT King County: To stay informed about potential hazards and threats that impact the Carnation area, including status updates on the Tolt warning system, sign up for ALERT King County.  

All materials PDF format unless noted as video.

Additional alerts and warning systems

The combination of outdoor and indoor siren locations is designed to reach as many people as possible in the Carnation area and is just one component of the emergency notification plan for the Tolt Dam. Other alert and warning systems that will be used in the event of an emergency include:

  • ALERT King County notifications sent to everyone who is signed up
  • Wireless Emergency Alerts sent to all available mobile devices in the area, similar to Amber Alerts. Double check that emergency and/or public safety alerts are enabled on your phones.
  • On-the-ground evacuation notices made by local police and firefighters in Carnation, including knocking on doors and loudspeaker messages
  • Emergency TV and radio alerts made to the Puget Sound area
  • Social media alerts posted by local agencies
  • National Oceanic and Atmospheric Administration (NOAA) and National Weather Service (NWS) weather radio warnings delivered
  • Local community notifications from family, friends, coworkers, and neighbors

Engagement & Collaboration

Community Outreach and City Council Updates: 2021-2024

Phase 1, Siren Replacement Project*

  • Design: 2021
  • Permits & Final Design: 2021-2022
  • Construction & Commissioning: 2023-2024 (we are here).

*SPU is actively working to boost volume and clarity on the new system by reprogramming the spoken voice, installing more powerful speakers for all the sirens, and adding two new siren locations: one at Tolt MacDonald Park and one at NE 60th.

Phase 2, Other Project Components**

  • Design: 2021
  • Permits: 2022-2024
  • Advertisement & Contracting: 2024
  • Construction & Commissioning: 2024

**Phase 2 components include digital highway message and fixed evacuation signs, additional indoor sirens, microwave link and data network improvements.

SPU is coordinating closely with contractors, vendors, and permitting authorities to complete this project. This information will be updated if supply chain challenges, permitting requirements, or other impacts change this schedule.

Seattle Public Utilities (SPU) owns and operates the Tolt Reservoir and Dams, located 16 miles upstream from the City of Carnation on the South Fork Tolt River. The reservoir stores 57,900 acre-ft of water to supply 30% of the drinking water for 1.6 million people in the greater Seattle area. Seattle City Light (SCL) owns and operates a system that generates power from water released from the South Fork Tolt Dam. Both SPU and SCL are bound to Federal Energy Regulatory Committee (FERC) requirements.

The Tolt Early Warning System alerts residents in the City of Carnation and in the nearby unincorporated area to evacuate in the unlikely event of a dam failure. The very first siren for the Tolt Dam area was implemented in 1978 as a single siren controlled by King County. The City of Seattle took over responsibility for the siren network in 1981 and the first improved network was installed in 1985. Additional improvements were made in 1993. The aging system, now in its fifth generation, is being replaced.

Public Utilities

Andrew Lee, General Manager and CEO
Address: 700 5th Avenue, Suite 4900, Seattle, WA, 98104
Mailing Address: PO Box 34018, Seattle, WA, 98124-5177
Phone: (206) 684-3000
SPUCustomerService@seattle.gov

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Seattle Public Utilities (SPU) is comprised of three major direct-service providing utilities: the Water Utility, the Drainage and Wastewater Utility, and the Solid Waste Utility.