Idaho Power and Rocky Mountain Power identified the study area that included the end points the transmission line needs to connect in order to serve customers. They then collected information on proposed and established energy corridors (e.g. West-Wide Energy Corridor (WWEC)) and a wide array of natural resources, land use, land ownership and other attributes to characterize the areas within the study corridor. The Companies also considered environmental and engineering constraints and opportunities when developing and evaluating potential corridors, with a commitment to minimize impacts to the environment and communities.

During the research and design stage the companies met with officials in the cities, counties and states in the project study areas to gather information, look at master plans and identify ordinances affecting the siting of the project. This information helped develop the initial proposed and alternative corridors which were presented at the BLM’s public scoping meetings in June 2008.

The public scoping meetings helped identify additional siting constraints, opportunities and alternate routes not previously considered. Using scoping information and additional route analysis, which included Idaho Power and Rocky Mountain Power’s meetings with landowners between December 2008 and January 2010, the BLM has determined which route alternatives to carry forward into a detailed analysis and released this information January 4, 2010. The analysis has been presented for public comment in the draft environmental impact statement (EIS), which also contains rationale for alternate routes not analyzed in detail.

The BLM identified agency preferred alternatives in August 2012 from the range of alternatives considered in the draft environmental impact statement, which were further presented in the final EIS, released in April 2013. Based on the agency preferred alternatives, the BLM released a record of decision for segments 1 through 7 and segments 10 in November 2013, while deferring a decision on segments 8 and 9 until routing can be resolved in this area.

The environmental review and routing process for segments 8 and 9 is ongoing. The BLM released an initial decision for segments 8 and 9 on January 19, 2017. On April 17, 2017, the Interior Board of Land Appeals remanded the decision back to the BLM Idaho State Office for reconsideration of the route alternatives.

To learn more about the routes being analyzed visit the route information page.

An energy corridor is defined as land (often linear in character) that has been identified through appropriate planning process as being a preferred location for existing and future utility rights of way (ROW), and that is suitable to accommodate similar, identical or compatible ROW.

The overall project approach was to conform to the WWEC and other designated ROW corridors where possible. The WWEC is designated only for federal land and land ownership in the project study area tends to be a mix of both federally managed and private land. The WWEC also tends to vary in width and in some cases it offers little or no opportunity to route directly within the WWEC due to required 1,500-foot offsets between existing and proposed lines and between sets of proposed lines, as determined by the Western Energy Coordinating Council.

The separation of the transmission lines into a north route and a south route improves the reliability of the transmission system. Separating the lines reduces the risk that both lines could be damaged by any one event, such as a wildfire or other natural disaster. By separating the lines, placing one on each side of the Snake River, a natural fire break is created that increases the reliability of the lines. This type of separation is not necessary for the project in Wyoming because other projects (Gateway South and Central) provide alternate transmission pathways serving the same purpose.