The Bonneville Power Administration released its draft proposed decision to join SPP’s Markets+, noting that a year after the agency issued its record of decision in favor of the market, preparations have advanced to a point where BPA can “move forward with implementation and propose joining Markets+ in October 2028.”

The draft decision differs from the agency’s day-ahead market policy and record of decision that it issued in 2025. Those were “a direction toward participation in Markets+” when the market was still in a “conceptual stage,” BPA staff said during a March 12 workshop discussing the decision. (See BPA Chooses Markets+ over EDAM.)

“We are pleased to share that we have advanced our planning for systems, processes and market implementation because of the rapid progress in Markets+ development,” BPA Administrator John Hairston wrote in a letter announcing the draft decision. “This progress in market development has allowed the agency to advance implementation planning efforts and further evaluate readiness requirements. We are now positioned to move forward with implementation and propose joining Markets+ in October 2028.”

Hairston touted Markets+’s day-ahead and real-time capabilities, writing the market would “ensure a reliable, affordable and abundant energy supply for consumers in the Northwest.”

The decision will allow BPA to continue preparing for market entry and work with customers on day-ahead market implementation, according to the letter.

Hairston’s letter briefly notes that in the lead-up to the earlier ROD, the agency found it would reap greater benefits in Markets+ than in CAISO’s Extended Day-Ahead Market.

The agency is not “revisiting” the issue. Rather, BPA seeks comment only on the March 12 draft decision, Hairston wrote.

Following the release of the ROD, BPA began reviewing its ability to satisfy Markets+ obligations. The agency joins not only as a market participant but also as a balancing authority, transmission operator and transmission service provider, and must therefore “have the capability to perform numerous tasks,” Hairston noted.

“Bonneville will continue to engage in proactive planning for both agency and customer Markets+ participation activities throughout this process,” according to the letter. “Bonneville’s customer and stakeholder engagement will be ongoing, including through its day-ahead market workshop series, tariff proceedings and rate case processes.”

The first wave of participants will join Markets+ on Oct. 1, 2027: Arizona Public Service, Salt River Project, Tucson Electric Power, Powerex and Xcel Colorado. BPA expects to join a year later alongside Chelan County Public Utility District, Grant County Public Utility District, Puget Sound Energy and Tacoma Power.

Stakeholders have until April 3 to comment on the draft decision.