Southwest Intertie Project

About us

The SWIP is being developed by Great Basin Transmission, LLC (“Great Basin”), an affiliate of LS Power. Great Basin is a project company whose purpose is to develop, finance, construct, own, and operate the SWIP.

LS Power is a power generation and transmission group engaged in the development, operation and management of large-scale electric generation and transmission projects in the United States. For more information on LS Power please



About the SWIP

Great Basin Transmission, LLC is developing the Southwest Intertie Project (“SWIP”), a 500 kV AC transmission line stretching between Idaho and southern Nevada. The 500+ mile line is being developed in response to the growing needs of the Desert Southwest and the Northwest. The SWIP will enable a diverse set of economic generating resources to serve loads that cannot currently be reached.

The SWIP is in the advanced stages of development with the southern portion between southern Nevada and the Thirtymile Substation being in-service as early as 2010 and the northern portion between Idaho and the Thirtymile Substation being in-service as early as 2011. Thirtymile Substation is a new interconnection with NV Energy’s (Sierra Pacific Power Company) 345 kV transmission system in Nevada.



The SWIP provides access to a larger pool of load and resources. During unexpected generation and transmission outages on the power grid the SWIP will provide critical import/export capability and increase grid reliability.


During peak times the Northwest relies on its hydro resources along with available thermal resources while the Southwest relies primarily on thermal resources. During off-peak hours and low or constrained water conditions the Northwest may need to conserve hydro and rely on other resource types, while the Southwest depends upon low-cost baseload resources. Because of difference in generating resource portfolios and the lack of bulk transmission, the Southwest and Northwest have historically been separated by large power price spreads. The SWIP will provide a path for the most economical energy to reach critical load centers.

Renewable Energy

Renewable generating resources are primarily located in areas far from major load centers. As a result, many renewables are captive to their local markets which prohibit their development. The SWIP will enable many of the best renewable resources in the west to have a path to key markets. The SWIP will allow the excellent wind resources found in northern Nevada, Idaho, Montana, and Wyoming as well as the vast geothermal resources found in Nevada and Idaho to reach markets in the southwest where wind and geothermal resources are not as favorable. In addition, the SWIP will allow the excellent solar resources found in the desert southwest to reach markets in the northwest.