Greater Portland Transmission Upgrades Projects

Central Maine Power (CMP) is proposing the Greater Portland Transmission Upgrades Project, a multi-year initiative to build a modern network of substations, upgraded infrastructure, and strengthened grid sections stretching from Yarmouth through Greater Portland.

 

These improvements are designed to: 

  • Proposed Project Needs Summary
    • Expand capacity to meet growing electricity demand.
    • Replace aging equipment.  
    • Enhance the reliability of the electric system for more than 200,000 customers.  

 

Although early in the process, this project aims to support this region’s future energy needs as more heat pumps, electric vehicles, electrified water transportation and renewable energy are utilized by our customers.

 

The proposed project includes a series of transmission and substation upgrades designed to strengthen the electric grid and support the Greater Portland region’s future energy needs.

 

View the Proposed Project Needs Summary to learn more about the improvements currently being considered. 

Map

 

Project Review Process  

Before we can begin detailed design and construction, this project must be reviewed and approved by the Maine Public Utilities Commission (MPUC). We submitted the application for review in September 2025. On July 16, 2026, the MPUC determined the application is complete and initiated a comprehensive and transparent review of the project’s merits, which will take place over the next twelve months. As required by the MPUC, we sent notifications about the project and the MPUC approval process to all project abutters. 

Information about the proceeding (Docket Number 2025-00276), including project filings, schedules, and opportunities for public participation, is available on the MPUC website.

 

Public Engagement and Open House Events

 

Upcoming Open House Events

We will be holding an upcoming series of open house events Yarmouth, Cumberland, Falmouth, Westbrook, and Portland. These events will be an open-house format with no formal presentation, so you're welcome to arrive at any time during the event. Meet with project team members, ask questions, and learn more about the proposed project. 

Enjoy friendly conversations, ask questions, and share your perspective. 

Information about these events will be mailed to all project abutters.

 

Yarmouth: 

  • Date: Wednesday, October 28, 2026  
  • Time: 6 p.m.-8 p.m. 
  • Location: Yarmouth Town Hall, 200 Main Street, Yarmouth, ME 04096 

Falmouth: 

  • Date: Thursday, November 5, 2026 
  • Time: 7 p.m.-9 p.pm. 
  • Location: Falmouth Elementary School Cafeteria, 52 Woodville Road, Falmouth, ME 04105 

Westbrook:  

  • Date: Monday, November 9, 2026 
  • Time: 6 p.m-8 p.m. 
  • Location: Westbrook Community Center, 426 Bridge Street, Westbrook, ME 04092 

Portland: 

  • Date: Tuesday, November 10, 2026  
  • Time: 6 p.m.-8 p.m. 
  • Location: Presumpscot Elementary School, 69 Presumpscot Street, Portland, ME 04103 

Cumberland:  

  • Date: Thursday, November 12, 2026  
  • Time: 6 p.m.-8 p.m. 
  • Location: Cumberland Town Hall, 290 Tuttle Road, Cumberland, ME 04021 

 

Previous open house events:

In December 2025, we hosted a series of informational open house events that provided residents, business owners, municipal officials, and other stakeholders with an opportunity to learn more about the project, ask questions, and provide feedback. We appreciate everyone who participated and helped inform our ongoing planning efforts.

Invitations for these events were mailed to all project abutters.  
Below are links to information that was provided at the 2025 public workshops: 

 

Contact us 

  • Project Information Line: 1.888.267.0831 
  • Email: outreach@cmpco.com  
  • Please refer to Greater Portland Transmission Upgrades Project in your message. 

Frequently asked questions

Central Maine Power (CMP) is proposing a major upgrade to the electric grid serving Greater Portland and surrounding communities. This initiative will strengthen the grid, improve reliability, and prepare communities for future growth as Maine’s economy and housing needs expand.

The proposed project route runs through areas of Yarmouth, Cumberland, Falmouth, Westbook, and Portland. 

NOTE: No work for the Greater Portland Transmission Upgrades Project has started. Any recent work in these areas has been part of our standard operations and maintenance work, including our Structure Replacement Program. Please see our project website for more information and work locations:  Structure Replacement Program.  

The investments proposed in the Greater Portland Transmission Upgrades Project are designed to: 

  • Support 200,000 CMP customers in and beyond Greater Portland and benefit all Mainers who rely on businesses and services in Southern Maine.  
  • Better protect critical facilities like hospitals, universities, businesses and residences from large-scale outages.  
  • Prepare for the future by adding capacity for new homes, businesses, and clean energy goals and address aging infrastructure near the end of its operational life.  
  • Improve storm resiliency so communities can recover faster from extreme weather.  
  • Help communities meet climate action goals by enabling electrification, renewable energy integration, and reducing reliance on fossil fuels.  
  • Upgrading two substations (Cumberland and East Deering). 
  • Rebuilding transmission lines in Westbrook and between Cumberland and Falmouth. 
  • Installing a new transmission line from Cumberland to Portland mainly using existing rights-of-way. 
  • Building a new substation near Portland’s wastewater facility. 
  • The project was submitted to Maine Public Utilities Commission (MPUC) in September 2025.  
  • If approved the project will take 3–4 years to complete.  
  • The MPUC determined CMP’s application to be complete in July 2026, and the review process could take up to one year.  
  • Reduces outage vulnerability in Southern Maine, the state’s economic hub.  
  • Creates backup connections so power can flow between communities during outages.  
  • Adds grid capacity to relieve energy bottlenecks and support housing, electrification, and renewable energy.  
  • For information about the MPUC review process, visit the MPUC website
  • For project information contact our Project Outreach team:  
    • Project Information Line: 1.888.267.0831  
    • Email: outreach@cmpco.com   
    • Please refer to Greater Portland Transmission Upgrades Project in your message.