Southwest Power Pool to Expand Into Western Interconnection Region

The Federal Energy Regulatory Commission on March 20 approved Southwest Power Pool’s (SPP) amended tariff which allows Western members to join the organization, making it the first regional transmission organization in the country to be operational in both the Eastern and Western interconnections. From April 2026, seven Western entities currently participating in SPP’s Western Energy Imbalance Service market can join SPP’s Integrated Marketplace, including transmission planning and reliability coordination.

SPP currently manages the wholesale electricity market for the central region of the U.S., covering 14 states, and operates crucial high voltage direct current lines that connect the Eastern and Western Interconnection regions. Once the seven Western Interconnection members have integrated into the market, SPP will look at including additional Western facilities.

Expanding SPP’s service regions to include Western members is a crucial part of Aspire 2026, the grid operator’s five-year strategic plan. The grid operator submitted its amended tariff to the commission on June 4, 2024, to facilitate the participation of Western entities seeking SPP membership or increase market participation. The seven Western entities include the Tri-State Generation and Transmission Association, Basin Electric Power Cooperative, Colorado Springs Utilities, Municipal Energy Agency of Nebraska, Platte River Power Authority, and the Western Area Power Administration Colorado River Storage Project, Rocky Mountain and Upper Great Plains regions.

In a significant boost for SPP’s Western marketplace growth, the commission approved the organization’s tariff to develop Markets+ in January 2025. SPP partnered with over 30 Western entities to establish Markets+, the regional, day-ahead energy market, set to commence operations in 2027.