Tolt Dam Early Warning System

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

March 13, 2023 project update:

Phase 1 Siren Testing for New System To Occur March 21 – 24

Seattle Public Utilities continues the commissioning process for the newly installed Tolt Early Warning System that includes five new outdoor and four new indoor sirens (annunciators) in Carnation, WA.

Another round of audible testing of the new siren system will take place March 21 – 24. Testing may happen intermittently between the hours of 9 am and 5 pm. Crews may need to test one siren at a time or all sirens at the same time. Audible testing may happen for a few minutes at a time. Sirens will not sound continuously for the entire day. It is possible that testing may not be needed for the entire week.

On Wednesday, March 22, the regular noon test of the existing siren system will take place, followed by a test of the new siren system within a few minutes. The new system test will include spoken messages in English and Spanish that this is a test and an oscillating siren tone. No other testing aside from the noon tests are planned to take place on Wednesdays.

Note: Double testing of the existing siren system followed by the new system will continue Wednesdays at noon starting on March 22.

When testing is complete and the new Tolt Dam siren system is fully commissioned, it will replace the existing system. As we get closer to this exciting milestone, SPU will stay connected to the community to ensure Carnation residents, businesses, and visitors are ready and know what to expect when the new siren system goes live.

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

Phase 2 of the project will include a variety of additional system components:

• Two additional outdoor sirens: one at Tolt-MacDonald Park and another near NE 60th St and 322nd Ave NE
• One new indoor siren at Riverview Learning Center
• Four new indoor desktop warning units
• Nine new electronic highway message signs
• 70 fixed evacuation signs

The project team is working with our partner agencies to secure the necessary permits for these components. Phase 2 of the project is expected to be completed in 2023.

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 are being installed at key locations within the inundation area. This includes replacing sirens at existing sites and identifying new locations for sirens and highway messages signs.

Here are the locations where the 4 new outdoor sirens and the 5 new indoor sirens (annunciators) have been installed for phase one of the project:

1.    35805 NE 80th St (outdoor siren)

2.    6921 Tolt River Rd NE (outdoor siren)

3.    5502 Tolt River Rd NE (outdoor siren)

4.    32421 E Entwistle St (outdoor siren)

5.    334th Ave NE and Tolt River Road NE (outdoor siren)

6.    4950 Tolt Ave –Elementary School (indoor annunciator)

7.    3740 Tolt Avenue –Middle School (indoor annunciator)

8.    3944 320th Ave NE – Bus Facility (indoor annunciator)

9.    3600 Tolt Ave – Fire Station (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 team plans to update the Carnation City Council and hold a community meeting in Spring 2023. Stay tuned for more information about these events as they are confirmed online.

Please subscribe to the project email list to receive up-to-date information throughout design and construction. 

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.  

• Project Update Mailer, December 2022/ Anuncio de actualización del proyecto de diciembre de 2022
• Siren Coverage Maps
• Video of Carnation Community Meeting, May 11, 2022
• Presentation to Carnation Community, May 11, 2022 (PDF)
• Video of Carnation Community Meeting, December 15, 2021
• Presentation to Carnation City Council, July 20, 2021 (PDF)
• Video of Carnation Community Meeting, June 30, 2021
• Presentation to Carnation Community, June 30, 2021 (PDF)
• Presentation to Carnation City Council, May 18, 2021 (PDF)
• Presentation to Carnation City Council, April 2, 2021 (PDF)
• Presentation to Carnation City Council, March 2, 2021 (PDF)
• Video of Carnation Community Meeting, February 24, 2021 
• Presentation to Carnation Community, February 24, 2021 (PDF)
• Presentation to Carnation City Council, August 3, 2020 (PDF)
• Presentation to Carnation City Council, Jan 19, 2021 (PDF)