Idaho Power eases impact of transmission line near Oregon Trail center

Idaho Power is changing part of its Boardman to Hemingway transmission line near the National Historic Oregon Trail Interpretive Center, replacing taller lattice-style towers with lower-profile H-shaped steel frames to reduce the project’s visual impact on one of Baker County’s best-known historic landscapes. The compromise matters because it shows how much influence local preservation pressure can have on a major regional utility project, even as the line continues to move forward.

The new line will run along the east side of Baker Valley and cross Highway 86 about a mile west of the interpretive center on Flagstaff Hill. The transmission line is not being built directly on Oregon Trail ruts or other physical traces, but Idaho Power and its partners acknowledged that towers and wires would still intrude on the view from the center and other nearby locations.

The change came through an agreement with the Oregon-California Trails Association, which works on preservation of the Oregon Trail and related emigrant routes. Dave Lewis, an OCTA member involved in the agreement, said the towers and wires would interfere with the vista visitors see from the center, and he said the H-frames made of weathered steel are more visually appealing there than taller steel lattice towers. Idaho Power spokesman Sven Berg said the H-frames cost more, and said the company worked through planning, design and construction to avoid Oregon Trail impacts where possible. He also said Idaho Power altered route segments elsewhere, shifted access roads and took other steps to reduce effects on historic resources, though not across Baker Valley.

The H-frame change is not just cosmetic. It does not remove the line from the landscape, and it does not hide the conductors from view, but it does reduce the apparent height and bulk of the structures closest to the interpretive center. That is significant at a site where the National Park Service says about one mile of Oregon Trail ruts lies on the center grounds, and where preservation advocates have pointed to roughly 40,000 annual visitors and argued that 170-foot towers less than a mile away would mar the historic setting.

OCTA said the agreement with Idaho Power includes more than tower design. Idaho Power will also pay for new Oregon Trail history signs near the center and in parts of Malheur County, adding a mitigation step beyond the immediate Baker County corridor.

The broader Boardman to Hemingway project remains one of eastern Oregon’s largest infrastructure builds. Oregon regulators approved the approximately 270.8-mile, single-circuit 500-kV line, which crosses Morrow, Umatilla, Union, Baker and Malheur counties and connects the planned Longhorn Substation near Boardman to Idaho Power’s existing Hemingway Substation in Owyhee County, Idaho. Idaho Power says the line is needed to meet growing customer demand and bring in reliable energy during summer peaks, when air conditioners and irrigation pumps strain the grid.

Idaho Power says it began the siting process in 2010, broke ground in 2025 and hopes to energize the line as early as 2027. In Baker County, though, the project has continued to draw legal fights and local resistance, including condemnation lawsuits and jury awards to landowners. Near Flagstaff Hill, the new tower design shows that even a project this large can still be reshaped by the historic ground it crosses.