NorthWestern Energy (NWE) conducted an Open Season Process to identify potential interest for new transmission capacity on the Montana to the Southwest path during December 2004. Transmission Service Requests (TSR) were accepted on NWE's Open Access Same-time Information System (OASIS) for new capacity on the path. Following is a summary of NWE's Open Season Process:

NWE's Open Season consisted of three phases. Phase 1 was the initial expression of interest period. NWE announced their plans for transmission expansion and asked for parties (generators, suppliers, load serving entities) to come forward with statements of interest for new transmission services from October 1-31, 2004. These parties were asked to specify the amount of capacity needed in 25 MW blocks, the direction of service, a start date, and the term of service. At the conclusion of Phase 1, NWE reviewed the level of interest and made a determination that there was adequate market demand to support their open season process.

Phase 2 began in mid-November 2004 with a posting of the time period to accept transmission service requests for the open season process. From December 1-31, 2004, NWE solicited transmission requests on the Montana to the Southwest path as point of receipt (POR) or point of delivery (POD) only and for new capacity. The Open Season solicitation involved the same process as a transmission service request under NWE's Section 17 Open Access Transmission Tariff except for two elements: (1) the initial deposit with the application was delayed, and (2) the system impact study and study fee was waived. Existing NWE customers with previously completed applications for transmission capacity were deemed part of the open season process. After the closing date of December 31, NWE began a detailed study that examined the size of line (i.e., 230 kV, 345 kV and 500 kV) and the transmission upgrades in Montana to move the power form its source to the northern terminal of the new line from Montana to Idaho.

Open Season Status

NWE initially received 17 OASIS requests totaling 2,250 MW of expressed interest. Using this information, NWE designed a high level study that would provide cost information regarding the need for transmission system improvements to move all or a part of the 2,250 MW to Idaho. This information was provided so the Open Season respondents could decide whether to proceed to the next level of study by funding their Open Season request. After NWE presented the results of this high level study, 850 MW of continued interest remained from the original participants. For those participants that elected to continue to the next phase, more studies have proceeded into the WECC Regional Planning Process and the NTTG Planning process.

In the fall of 2006, NWE engaged Power Engineers, Inc. to conduct a siting study and preliminary engineering report for the Montana to Idaho pathway. The study included determining alternative routes, various voltage options, AC vs. DC, design criteria, conductor and structure selection, and estimated costs on the various options. NWE commenced the siting and permitting and environmental process for the project in the spring of 2007. As part of the Major Facility Siting Act (MFSA) process, NWE named the line the Mountain States Transmission Intertie (MSTI) and issued a press release in June 2007 announcing the details of the proposed new transmission line. As a result of this, NWE received 500 MW of additional transmission service requests for a current total of 1,350 MW of capacity on the MSTI line, which was formerly called the Montana to the Southwest or Montana to Idaho pathway. These new TSR's will be handled like any other NWE receives with the date and time determining the customer's position in the Transmission Service Queue.