Northern Maine Transmission: What Was Decided This Summer

This summer, two separate processes reached major decisions about bringing power from new wind projects in northern Maine to the rest of New England. One was run by the Maine Public Utilities Commission (PUC); the other by ISO New England, the regional grid operator. Here’s what each decided, how they fit together, and what happens next.

The state decision: Maine PUC

Under Maine’s Northern Maine Renewable Energy Development Program, the PUC ran a competitive procurement for both new transmission and new generation.

• August 25, 2026: The PUC announced its selections: Avangrid, the parent company of Central Maine Power (CMP), to build the transmission line, and Clearway Energy Group for generation.
• September 4, 2026: The PUC issued its order on the bid proposals in docket 2026-00033.

Clearway’s County Line wind project is planned at 800 megawatts in total. The Maine PUC awarded 600 MW, Rhode Island has conditionally awarded 150 MW, and the remaining 50 MW has not yet been awarded.

Details of the winning bids, including prices, have been treated as confidential.

The regional decision: ISO New England

Separately, at the direction of the New England States Committee on Electricity (NESCOE), ISO New England ran a request for proposals for longer-term transmission upgrades.

• July 28, 2026: ISO-NE released a draft report naming a joint Central Maine Power and Eversource proposal as its preliminary preferred solution.
• August 3, 2026: ISO-NE clarified that under a potential downside scenario, costs for the selected proposal could be 167% higher than estimated.
• August 14, 2026: ISO-NE published its final report confirming the CMP and Eversource proposal.
• September 15–17, 2026: The project, now called the Transmission Initiative Down East (TIDE), was selected for development. NESCOE did not end the process, and cost allocation was finalized.

TIDE’s costs will be shared among the six New England states based on each state’s share of peak electricity demand. CMP and Eversource will now sign an agreement to proceed.

How the two fit together

The state project would build new transmission from Haynesville to Pittsfield to connect new wind generation in northern Maine to the grid. The regional project expands the grid’s ability to move that power south toward the rest of New England, where demand is highest. Both are paid for by electricity customers: the state project mainly through Maine contracts, and the regional project through costs shared across New England.

CMP has since released a route map for the Haynesville-to-Pittsfield line.

What comes next

• CPCN: Before construction, the transmission line will need a Certificate of Public Convenience and Necessity (CPCN) from the PUC. Landowners, towns, and organizations can seek to take part formally in that proceeding.
• ISO-NE review: ISO-NE plans to begin a “lessons learned” review of its transmission RFP at the Planning Advisory Committee by the end of 2026. Those meetings are open to the public.

Questions we’re asking

• How much will these projects cost Maine ratepayers, once both state and regional costs are counted?
• How much of the power will reach Maine customers?
• Why have bid details been kept from the public?
• How many miles of new corridor will rural communities host, and what will they receive in return?

Preserve Rural Maine will keep following both processes and share deadlines and opportunities to participate. For the full timeline, see our Northern Maine Transmission & Wind page.

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