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Puget Sound Energy electric transmission line project

Ebey Slough transmission line

Fall 2008 project completion
  • PSE completed construction of the Ebey Slough transmission project in October 2008

Project overview

Download full-size map
Project Map (1.59 MB PDF)

As a major component of the region's electrical transmission grid and because of the rapidly changing environmental conditions in Ebey Slough, it was critical that Puget Sound Energy replace its old transmission lines in the slough. The old lines were supported by wood H-frame structures, which were not designed to be in standing water. The environmental aspects of the slough created problems for the stability of the transmission lines. In some cases, anchors and guy wires had pulled out of the soft, saturated soils resulting in unstable structures that were not anchored in load-bearing soil.

The Ebey Slough transmission lines are vital to the stability of the region's entire transmission system. In order to protect system safety and reliability, in 2008, PSE replaced the existing, deteriorating poles with new transmission line structures that can withstand the changing conditions of the basin.

Unstable transmission lines
before installation of new
transmission lines - Nov. 2006

PSE's new transmission line
standing in eight to 10
feet of water in Ebey Slough
after installation - Jan. 2009.
Click on a photo to see
an enlarged version

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.

Download information

Download these PDF files for more detail on PSE's Ebey Slough electric transmission project. 
News Release (10/23/08) 
News Release (05/16/08)
Ebey Slough Presentation (2 MB PDF)
Project Need, May 2007 (93 KB PDF) 
Project Update, May 2007(218 KB PDF)
Project Update, July 2007 (218 KB PDF) 
Project Map (1.59 MB PDF)
Wire Clearance (175 KB PDF)