FERC Orders CAISO and SPP to File Western Seams Report by Sept. 30, 2026

On July 16, 2026, the Federal Energy Regulatory Commission (FERC) ordered two major Western grid operators—California ISO (CAISO) and Southwest Power Pool (SPP)—to submit a joint report on how they coordinate across the “seams” where their systems and markets meet.

The filing is due September 30, 2026. FERC also tied the matter to a public-comment process focused on the report’s seams-management and market-coordination issues.

What FERC ordered, and what CAISO and SPP must deliver

In an order tied to the Commission’s July 16 meeting (Docket AD26-10-000, “Western Seams Coordination”), FERC directed CAISO and SPP to “detail their progress” coordinating operations along their seams.

FERC’s scope is broader than a single boundary: the report is meant to cover seams between the SPP and CAISO markets themselves, and also between either the SPP or CAISO markets and neighboring balancing authorities.

Per FERC, the joint report must address:

• Current coordination initiatives.
• Specific operational challenges arising from new market developments.
• Plans and schedules for resolving those issues.
• Areas where the operators have not yet aligned.

What “seams” coordination means in plain language

Power-grid reliability isn’t confined to a single operator’s control room. Where transmission and balancing responsibilities meet, different market rules and operational practices can create friction—especially as Western grid footprints change.

In that context, “seams” are the interfaces where coordination needs to be consistent—so reliability is maintained and power flows and market outcomes don’t become unnecessarily inefficient at the points where regions meet.

Timeline readers should track: Sept. 30 filing and the 30-day comment window

After CAISO and SPP file the joint report on September 30, 2026, FERC will accept public comments for 30 days post-filing.

FERC specified that comments must focus solely on the seams-management and market-coordination topics addressed in the report.

What this does—and doesn’t—mean for reliability right now

This order is not a promise of immediate operational changes. What FERC has required is a structured account of “progress,” including where coordination is working, where operational challenges are emerging, and where alignment is still incomplete—so the Commission can decide what (if anything) should come next.

For residents and grid-facing businesses, the key “next” signal will be what CAISO and SPP put into the Sept. 30 report—and how stakeholders use the comment window to press for specific coordination expectations at the seams.

Sources

• FERC news release (July 16, 2026): “FERC Orders Western Grid Operators to Deliver Joint Report on Grid Coordination”
• E&E News by POLITICO: context on FERC calling for Western power-market transmission coordination