An example of how an Idaho Power substation appears in a rural setting.

The Treasure Valley electric load – or demand on the system – increases by about 50 megawatts annually. That’s equal to adding a city the size of Eagle each year. A growth rate like this will soon strain Idaho Power’s infrastructure if nothing is done to reinforce it. 

This transmission line project will address growing demand in the Treasure Valley and will improve the overall reliability of the existing transmission system. It will help deliver power from the edge of the Treasure Valley into the center where the power is used.

Under certain conditions, transmission capability in the Treasure Valley is approaching full capacity. This project is needed to meet the projected electrical demand of the future. As a transmission provider, Idaho Power has the obligation to plan and construct transmission facilities to ensure reliable electric service to its customers.

Transmission Line Details
The new 230-kilovolt (kV) transmission line would be 12 to 14 miles long depending on the line route.

The line would consist of two 230-kV circuits connecting Bowmont Substation to the proposed Hemingway substation.

Bowmont Substation is located near Southside Boulevard and Rose Lane in southern Canyon County. Hemingway Substation's proposed location is in northern Owyhee County, south of the Snake River about two miles west of the Idaho 45 and 78 highway junction.

The transmission line would be built using single steel poles about 100 feet in height with pole spacing about 800 feet. Exact dimensions and spacing will vary depending on the line route selected. Current plans are to have the line constructed mid-year 2010.

Hemingway Substation
This proposed substation would be served from Rocky Mountain Power’s 500-kV transmission line, which is near the proposed station location.

Idaho Power is in the process of acquiring property for the station and a conditional use permit for construction. The station will initially consist of 500-kV and 230-kV switching equipment and 500-kV to 230-kV transformers. 

Project Schedule

Check out our Electric Facts, learn more about electricity, or how Idaho Power plans for growth. View a map (PDF, 9,759KB) of the project showing potential line routes. After the public input process, Idaho Power will select one route.