Washington State's Grant County Public Utility District and Tacoma Power announced their commitment to join Markets+, Southwest Power Pool’s western day-ahead and real-time market, on Oct. 1, 2028, SPP reported on Feb. 27.
Their participation will further expand the footprint of Markets+, a regional wholesale energy market designed to improve grid reliability and deliver cost savings across the Western Interconnection.
“The addition of Grant County PUD and Tacoma Power reflects the continued growth and momentum of Markets+ across the Pacific Northwest,” said Carrie Simpson, SPP vice president of markets. “These utilities recognize the value of a market built on strong governance, reliability and cost savings for their customers. We look forward to our continued partnerships building a market that works for the entire Western Interconnection.”
Both Pacific Northwest entities previously signed funding agreements to support Markets+ development but had not announced a date for their market participation. "Their commitment adds to growing momentum for a market that has already drawn broad support from utilities, regulators and other stakeholders across the west," SPP said.
Arizona Public Service, Powerex, Public Service Company of Colorado, Salt River Project and Tucson Electric have already signed agreements to participate in Markets+ when it launches in October 2027.
Grant County PUD and Tacoma Power join Puget Sound Energy and Chelan County PUD, which previously announced their intention to participate in Markets+ one year later as part of the second wave of entrants.
Additionally, the Bonneville Power Administration (BPA) established a policy decision May 2025 to pursue participation in Markets+. BPA’s participation would bring the largest power marketing agency in the Pacific Northwest into the Markets+ footprint, underscoring the market’s growing appeal among diverse utilities across the region.
Grant County PUD is a consumer-owned utility in central Washington, serving approximately 56,000 customer meters. The district operates more than 2,100 megawatts of hydroelectric generation and is one of the largest public utilities in the Pacific Northwest.
“Grant PUD’s mission is to deliver reliable and affordable energy to our growing customer base,” said John Mertlich, Grant PUD CEO/GM. “Joining SPP’s Markets+ is a strategic step that strengthens our ability to do so. Additionally, joining Markets+ aligns us with a growing coalition of utilities across the West who are working toward a more reliable, interconnected, and economically integrated regional power grid.”
Tacoma Power, a division of Tacoma Public Utilities publicly owned since 1893, provides electricity to approximately 186,975 customers in Pierce County, Washington. The utility’s generation portfolio is anchored by hydroelectric resources on the Cowlitz and Skokomish rivers.
“Markets+ reflects the power of regional collaboration," said Chris Robinson, Tacoma Power general manager. "Diverse utilities united around a common purpose: building market solutions that enhance resource adequacy and grid reliability. Our partnership has created an independent governance that optimizes our resources, ensuring we can meet demand reliably and affordably while delivering sustained benefits to customers throughout the West. I’m excited that years of effort is resulting in concrete go-live commitments from so many electric utilities, and I'm proud that Tacoma Power will begin participating in 2028.”
Markets+ is a day-ahead and real-time market designed to centralize unit commitment and enable reliable integration of renewable generation across the Western Interconnection, SPP noted.
The market features an inclusive, stakeholder-driven governance structure that provides participants an equal voice in market design and operations.
SPP filed the Markets+ tariff with the Federal Energy Regulatory Commission March 29, 2024, and FERC approved the tariff Jan. 16, 2025. The first wave of market participants is expected to go live in 2027.
