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Puget Sound Energy electric transmission and substation project​

Bainbridge Island transmission line and substation

Winter 2012-13 project updates
  • The community's power consumption stayed well below the trigger level of 58 MW over the 2011-12 winter season.
  • At the February 1, 2012 Bainbridge Island City Council meeting, PSE reminded city council members and island citizens to continue monitoring the island-wide energy dashboard and take steps to reduce electric consumption on the coldest days of the year.
Project overview

PSE's analysis of the electric needs on Bainbridge Island has determined the two substations serving two-thirds of Bainbridge Island – Murden Cove built in 1980 and Winslow built in 1966 – are approaching their maximum capacity. On cold winter days, high electric usage on the island (known as "peak load") forces the transformers to operate at levels well above designed capacity. This threatens to damage the substation equipment, increases the risk for system failure and could cause potentially lengthy outages and expensive repairs. In addition, overloading substation equipment beyond certain limits results in an accumulative loss of equipment life that can lead to premature failure. Compounding this peak load problem, both substations are served by only one transmission line. If the line serving one of these substations goes out, the substation will shut down and thousands of customers will lose power.

After several years of research and customer and community discussions, PSE has developed a multi-faceted electric system improvement plan to address these electric capacity and reliability issues. The plan includes energy efficiency initiatives, continued vegetation management and distribution improvements and possible investments in new infrastructure, including a new or expanded substation and new transmission line.

Focus on energy efficiency initiatives

PSE will postpone submitting planned substation and transmission infrastructure project-related permit applications until after the winter of 2012-13 at a minimum unless natural disaster related emergency conditions or system operational needs dictate otherwise, allowing the community time to put energy efficiency measures to work to reduce energy usage on the island.

Continue vegetation management and distribution improvements

PSE will maintain the ongoing program of trimming trees that threaten the electric transmission and distribution system on the island. PSE will also continue to identify and improve the segments of the distribution lines that are most prone to outages, with investments in several projects over the next few years (see 2011-12 planned projects map).

Ensure continued electric capacity and reliability on the island

If after three years of monitoring the community peak load reaches 58 megawatts, PSE will move forward with plans to expand substation capacity and to connect our Winslow substation to our Murden Cove substation with a transmission loop.

For more information about our plan, please download our FAQ and letter to the community.

Contact us:

For more information on this project, e-mail or call Heather Brickey, project manager, at 425-456-2848. You may contact us via U.S. mail at:

Attn: Bainbridge Project PSE-09S
Puget Sound Energy
PO Box 97034
Bellevue, WA 98009-9942

RePower Bainbridge

RePower Bainbridge is a community group committed to helping reduce energy usage on Bainbridge Island. For more information on RePower Bainbridge or to participate in energy efficiency initiatives on the island, please call 1-877-741-4340.

Bainbridge map
Download full size map

Project map
(445 KB PDF)

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.

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.

2009-11 Bainbridge Island Demand Response Pilot

The Bainbridge Island Demand Response Pilot ended in September 2011. Please click on the letters below for information regarding Demand Response Pilot load control equipment removal.

Demand Response equipment removal letter, September 2011
Demand Response equipment removal letter, August 2011

Access PSE's Safety Notice about the White-Rodgers thermostats being used by Bainbridge Island Demand Response Pilot program participants with heat pumps.

Download the information

Download these PDF files for more detail on the Bainbridge Island substation and 115 kV electric transmission project.

February 2012 update to Bainbridge City Council
Bainbridge City Council presentation (2/1/2012) (894 KB PDF)
2011-12 planned projects map

October project announcement 2010

Bainbridge City Council presentation (10/6/2010) (2 MB PDF)
Bainbridge FAQ
Community input
Bainbridge letter to the community

April and May meetings 2010
Meeting invite, April 2010


Meeting invite, rev. April 16, 2010
Print ad

Bainbridge Review article
Comment card

Bainbridge Review guest column
Existing conditions
Existing conditions
Includes information on existing infrastructure, energy demands and history of island electricity

Infrastructure solutions – 3 options
Infrastructure solutions – 3 options
Options comparison matrix
Includes information on three options for infrastructure improvement

Site and route options
Transmission line route options
Substation site options
Includes information on transmission line route options, and site options for expanding an existing substation or building a new substation
Capacity challenges
Capacity challenges
Includes information on island peak energy demands

Energy efficiency
Energy efficiency, revised April 2010
Energy efficiency
Includes information on island energy efficiency programs and demand response pilot
Reliability challenges
Reliability challenges
Outage poster, revised April 2010 Includes information on island power outages and history of infrastructure improvements

Project timeline
Project timeline
Includes information on the current project timeline

October meeting 2008 April meeting 2009 August Meeting 2009

Kitsap Sun article

Bainbridge Review article

Environmentally sensitive areas

Substation site objectives

Opportunities for community input

Peak load chart

Community Ad

Bainbridge Island fact sheet

Existing facilities on Bainbridge Island

Existing facilities on South Bainbridge Island

Substation photos

Planning for reliability flow chart

Presentation, April 20, 2009

Meeting invite, April 2009

Combined growth graph

Environmentally sensitive areas

Existing facilities on Bainbridge Island

Existing facilities on south Bainbridge Island

Existing substation photos

Peak load information

Planning for reliability

Route segment options

Is there a better site for a future substation?
Meeting invite

Substation alternatives

Undergrounding transmission, (revised Aug. 2012)

Presentation Aug. 25, 2009

News release (Oct. 7, 2009)