An interactive online map released in November provides the most detailed information yet about the potential design of the Bonneville Power Administration’s proposed I-5 Corridor Reinforcement 500-kilovolt transmission line in southwest Washington.

The new map shows BPA's preliminary designs with tower locations on the existing and proposed new rights-of-way (typically 150 feet wide) for each potential segment of the new line.

The map refines years of preliminary examination of routes for the proposed high-voltage transmission line. The proposed project is needed to resolve a critical electric bottleneck that could otherwise lead to outages in southwest Washington and northwest Oregon as early as 2016. No new 500-kV power lines have been built in the area in nearly four decades, although the area population has doubled.

“We are following up on our commitment to keep the public informed and involved, said Larry Bekkedahl, vice president, BPA Transmission Services Engineering and Technical Services. “We hope these new map details will give people a better idea about how the line would be designed.”

The best way to see the potential power line locations is to look at the interactive Google project map online. In addition, BPA will provide printed copies for anyone without internet access.

“This is a great opportunity for people to use this new information and provide us with more detailed comments about the impacts the towers and line locations may have on them and their property.” said Mark Korsness, BPA project manager. “This preliminary design and the resulting comments we receive will allow us to study the project’s potential impacts in more detail.”

It is important to note that the map is preliminary. Proposed locations could change as BPA learns more about the areas where it has placed proposed lines. It is highly unlikely, however, that any repositioning would involve moving any of the alignments outside the specific land parcels whose owners have already been notified about the project. The interactive map and other project information are available at

BPA will now focus on studying the potential impacts on each proposed route segment, which are identified on the map by numbers and letters. That analysis will help BPA link the segments together into one or more route alternatives between the proposed new substations in Castle Rock, Wash., and Troutdale, Ore. This work will lead to identifying a preferred route, which could be announced next fall in the draft environmental impact statement.