Montana-to-Washington Transmission System Upgrade: Scoping Materials (July 2025)

Montana-to-Washington Transmission Upgrade Project; Multiple Locations in Montana, Idaho, and Washington

Bonneville Power Administration (BPA) is proposing to upgrade parts of its existing transmission system in Montana, Idaho, and Washington as a result of recent requests for transmission service from its customers. These improvements and additions would include:

• Construction of a new Moose Gully Compensation Substation adjacent to the existing BPA Garrison-Taft No. 1 & 2 500-kilovolt (kV) transmission lines, located near the Miller Creek neighborhood in Missoula, Montana, and a new microwave tower either within the new substation yard or a short distance away to facilitate a communications pathway to the Miller Peak Radio Station.
• Replacement of electrical wires along approximately 11 miles of BPA’s existing Dworshak–Taft No. 1 500‐kV transmission line in northeastern Idaho and western Montana, which would also require improvements to existing transmission line access roads.
• Electrical equipment upgrades at five existing BPA substations and possible expansion of substation yards at BPA’s Hatwai Substation in Idaho and Bell Substation in Washington.

Click here for an interactive project location map.

For more information, see BPA's Montana-to-Washington Transmission System Upgrade website.

Public Comment Opportunities

BPA is requesting public scoping comments to help determine the issues that should be addressed in the environmental review by August 10, 2025.  When commenting, refer to the full project name. All comments will be posted on the BPA comment website.

There are several ways to comment:

Online: https://publiccomments.bpa.gov/
Mail: Bonneville Power Administration
Public Affairs – DKE-7
P.O. Box 14428 Portland, OR 97291-4428

Toll-Free: 800-622-4519
Fax: 503-230-4019