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Puget Sound Energy electric transmission line project

Thurston 230 kV transmission line

Winter 2014 project updates
  • We expect to start construction on the transmission line (see project map) in February 2014 and anticipate completion by June 2014.
  • Construction on the St. Clair substation in Olympia began in early January 2013 and was completed in late September 2013. Crews replaced and added new electrical equipment to the substation; this work will allow us to connect the new transmission line into the substation.
Project overview

Puget Sound Energy plans to install approximately 3.2 miles of new 230 kilovolt transmission line between the St. Clair substation, 9512 Pacific Highway SE in Olympia, and an interconnection point on the Bonneville Power Administration's South Tacoma-Olympia 230 kV transmission line ( See map for location ).

We are constructing the new transmission line to increase the capacity and reliability of the regional electric transmission system for more than 120,000 customers in Thurston County. We estimate that our existing Thurston County transmission system will reach capacity in 2013. Adding the new transmission line will allow PSE to respond to the county's growing need for power while increasing overall reliability.

Download full-sized map
Project map

We will also expand the St. Clair substation within the existing property boundaries to accommodate the new transmission line.

What is a transmission line?

Transmission lines are key elements in the electrical distribution system. The lines safely transport high voltage electricity from power generation sources like dams and wind generating facilities to substations in local communities. Transmission normally takes place at voltages of 55 kV and higher.

What is a substation?

Substations are critical links in the electricity distribution system, containing utility circuit protection, voltage regulation, and equipment that steps down higher voltage to lower voltage. Before reaching homes and businesses, power is routed through our transmission system to a substation where it is changed to a lower voltage that can be utilized by customers.

Contact us:

For more information on this project, email Project Manager Heather Brickey at

Committed to keeping you informed

PSE will continue to provide updates to the community. We will notify residents and businesses near the project area when construction will occur. We aim to complete the work with as little disruption as possible.

For information on electric and magnetic fields, please view PSE's EMF statement.

Download the information

Download these PDF files for more detail on our Thurston 230 kV electric transmission project.

Project update letter, November 2011
Project aerial map
Project road map

February 2010 public meeting

Meeting invite, February 2010
Newspaper ad, February 2010
Project map
Aerial map of study area
Fact sheet, February 2010
Thurston County project need, Feb. 22
Alternative solutions, Feb. 22
Route selection evaluation criteria, Feb. 22
New 230 kV transmission line, Feb. 22
Thurston County planned transmission projects, Feb. 22
Crosscountry utility landscaping zone, Feb. 22
Roadway utility landscaping zone, Feb. 22

October 2009 community advisory group meeting

Community advisory group presentation, Oct. 15, 2009