FERC has issued a deficiency letter over SPP’s proposed revisions to its tariff, bylaws and membership agreements intended to facilitate nine western entities’ RTO membership as transmission owners.

In an Oct. 3 letter, the commission said SPP’s filings are deficient and that it needs more information to process them. It asked the grid operator to submit its responses by Nov. 4 (ER24-2184, ER24-2185).

FERC asked for more information on:

• • Any existing tariff provisions that will facilitate the transition of the new members’ transmission service request queues into SPP’s current service-study processes.
  • The proposed tariff’s provision that the Western Area Power Administration-Colorado River Storage Project’s replacement energy is “necessitated by WAPA-CRSP’s inability to deliver sufficient energy from reservoir projects under the control of the U.S. Bureau of Reclamation in the marketing area of WAPA-CRSP for reasons such as persistent drought or environmental constraints.”
  • New metered boundaries and the need to establish a second balancing area authority that will be incorporated into SPP’s markets.
  • How separate reference buses in the market’s two balancing authority areas will accurately model the marginal cost of serving load in each BAA, including the cost of congestion.
  • How LMPs on both sides of the West DC ties will inform how SPP optimizes the interties’ usage.
  • Which rate(s) under the tariff revisions would apply to point-to-point transmission service where the load is located within a BAA external to the SPP Region but not interconnected to SPP’s eastern or western market.

SPP filed the tariff for its western RTO expansion in June as it seeks to become the first grid operator with markets in both the Western and Eastern Interconnections. It says its RTO West will provide more than $200 million in annual benefits to its members. (See SPP Files to Incorporate Western Entities into RTO.)

RTO West is scheduled to go live in April 2026.

FERC also filed a deficiency letter for SPP’s Markets+ tariff, another of the RTO’s western services. Saying deficiency letters are part of a “routine process, SPP staff responded to the letter in September and asked for an order by Nov. 20. (See SPP Dispels Concerns over Markets+ Deficiency Letter.)