Tolt Dam Early Warning System

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

September 1, 2023 update

Seattle Public Utilities is close to fully activating the new Tolt Dam Early Warning System and taking the old siren system offline. This is scheduled to occur by the end of October 2023 and will mark the completion of Phase 1 of the project.

As soon as we have a go-live date for the cut-over to the new system, we will announce it on this web page and provide additional information to the Carnation community.

Please note that we are continuing to work on enhancing the new system to boost the speaker volume and add clarity to the voice commands. That work is in process and will continue over the next few months.

Phase 2 of the project will begin later this year and 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
  • Outdoor siren 8 moving from Tolt River Road N and 334th Ave NE to the Carnation public works yard 
  • One new indoor siren at Riverview Learning Center
  • Four new indoor desktop warning units
  • 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 2024.

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

August 23, 2023 update:

ALERT: Today’s noon test of the Tolt Early Warning System will take place as scheduled. However, the old siren across from Nick Loutsis Park will not sound today. (This is the siren that accidentally sounded yesterday. See yesterday’s update below). It continues to undergo antenna repair. The new siren at the same location will be tested as usual and will sound off at approximately 12:03 pm.

August 22, 2023 update:

On Tuesday, August 22, while staff were performing minor work on the old (soon to be decommissioned) Tolt Dam Early Warning System, the siren across from Nick Loutsis was accidentally set off.

Seattle Public Utilities (SPU) staff immediately verified that the dam was safe and began communicating to its partners and stakeholders, including City of Carnation officials, to alert that the alarm was false.

In addition to the Early Warning System, SPU always has staff visually monitoring the dam 24/7.

SPU sincerely apologizes for any confusion or concern this might have caused the residents of Carnation who heard the alarm sound.

Please know that Seattle Public Utilities take incidents like this seriously, and we are reviewing our protocols with the goal of meeting community expectations.  It is our top priority to decommission the old system and commission Carnation’s new state-of-the-art Tolt Dam Warning system as soon as possible.   

We appreciate the public’s help in reporting any unusual sounds from the system. Please feel free to reach out to our project manager, Josh Campbell at josh.campbell@seattle.gov if you have observations or questions.  

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.  

All materials PDF format unless noted as video.

Siren Replacement (existing outdoor and indoor locations)

  • Quarterly community meetings begin 1st Quarter, 2021
  • Design completed 3rd Quarter, 2021
  • FCC (Federal Communications Commission) Permits issued 4th Quarter, 2021
  • Final Design completed 2nd Quarter, 2022
  • Construction completed 1st Quarter, 2023

Other Project Components (highway message signs, additional siren locations, microwave link and data network improvements)

  • Design completed 1st Quarter, 2022
  • FCC (Federal Communications Commission) Permits issued 2nd Quarter, 2023
  • Construction completed 4th Quarter, 2023

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 1.5 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.