Chris Morse answers questions for Issaquah residents at the open house event on May 2. Evan Pappas/Staff Photo

Chris Morse answers questions for Issaquah residents at the open house event on May 2. Evan Pappas/Staff Photo

BPA addresses tree removal along transmission line corridor in Issaquah and Sammamish

Citizens attended a BPA open house at Blakely Hall in Issaquah on May 2.

Citizens with questions about the removal of vegetation along the Sammamish-Maple Valley transmission line gathered at Blakely Hall in the Issaquah Highlands for a Bonneville Power Administration open house on Thursday, May 2.

The federal energy company Bonneville Power Administration (BPA) is resuming operations and maintenance of the Sammamish-Maple Valley transmission line after a 50-year lease to Puget Sound Energy (PSE). Under BPA operation, the corridor the line runs through will undergo changes to comply with the administration’s more conservative vegetation and safety policies.

Citizens attended the open house presentation to ask questions about how their property adjacent to the line would be affected by increased vegetation removal and safety regulations.

From the center of the transmission line, the easement of the corridor stretches 75-feet to either side, creating a 150-foot corridor. Under PSE, vegetation around the area that could have interfered with the line itself was removed up to 42-feet from the center. BPA’s policy will increase that range to 62.5-feet.

Because BPA works with high-voltage electricity across the northwest including Washington, Oregon, Idaho, and parts of states like Montana and California, it does not have the same vegetation management timetable as PSE would. While PSE worked on a one-year cycle, BPA’s program is on a three-year cycle resulting in a more conservative management policy.

Attendees of the open house asked BPA representatives about how adjacent properties would be affected by the use of some herbicides to control weeds and regrowth of previous addressed plants. People were concerned about the safety of the herbicide, environmental impacts, and when and how BPA uses it.

Chris Morse, a natural resource supervisor, said the use of the herbicide was specific to the target vegetation and its use is governed by strict policies BPA has in place. The herbicide itself, triclopyr, is only about one percent of the solution that is sprayed on plants. Crews have sprays loaded on backpacks and individually target vegetation as they work their way down the transmission line corridor.

Morse noted that the crews do not spray the vegetation during wind, after it rains or near water at all. He also said crews and BPA management will stop work if land owners have concerns. BPA then works with land owners for a solution or to address concerns before any more work continues.

Morse said once the herbicide solution dries it does not transport, and that’s why the administration avoids spraying in or around water, or after it has rained.

Vegetation management isn’t the only work BPA will be doing along the corridor. To improve safety for workers, crews will begin replacing the existing non-ceramic insulators on 30 towers in the corridor with insulators of better material composition. In 2020, work is planned to replace two miles of transmission line from Dahlia Park in Issaquah to Beaver Lake Park in Sammamish.


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A map of the Sammamish-Maple Valley Transmission Line and the Monroe-Novelty-Hill Transmission Line. Courtesy Image

A map of the Sammamish-Maple Valley Transmission Line and the Monroe-Novelty-Hill Transmission Line. Courtesy Image

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