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: 

  • Replace aging equipment.  
  • Expand capacity to meet growing electricity demand.  
  • 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.  


 

Our community partners:

  • City of Portland
  • Town of Falmouth
  • Town of Yarmouth
  • City of Westbrook
  • Town of Cumberland
  • Greater Portland Council of Governments
  • Portland Regional Chamber of Commerce

 

Community Open Houses  

CMP is hosting a series of Community Open Houses in towns along the proposed route — including Portland, Falmouth, Yarmouth, Cumberland, and Westbrook. These events will provide opportunities to learn more, ask questions, and speak directly with project representatives. 

 

Yarmouth 

  • Date: Monday, December 8 
  • Time: 5pm-7pm 
  • Location: Yarmouth Town Hall, Community Room, 200 Main Street, Yarmouth 

Portland

  • Date: Tuesday, December 9
  • Time: 5pm-7pm
  • Location: Presumpscot Elementary School, 69 Presumpscot Street, Portland, ME 04103
     

Westbrook 

  • Date: Thursday, December 11 
  • Time: 6pm-8pm 
  • Location: Westbrook Community Center 

Cumberland  

  • Date: Monday, December 15 
  • Time: 5pm-7pm 
  • Location: Cumberland Town Hall, 290 Tuttle Road, Cumberland Center, ME 04021 

 

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. 


 

  • Supports 200,000 CMP customers in and beyond Greater Portland and benefits all Mainers who rely on businesses and services in Southern Maine. 
  • Better protects critical facilities like hospitals, universities, businesses and residences from large-scale outages. 
  • Prepares for the future by adding capacity for new homes, businesses, and clean energy goals and addressing aging infrastructure near the end of its operational life. 
  • Improves storm resiliency so communities can recover faster from extreme weather. 
  • Helps 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. 
  • MPUC’s expert review is anticipated to take 8-12 months. 
  • If approved, work begins in 2027 and will take 3–4 years to complete. 
  • Reduces outage vulnerability in Southern Maine, the state’s economic hub. 
  • Adds grid capacity to relieve energy bottlenecks and support housing, electrification, and renewable energy. 
  • Creates backup connections so power can flow between communities during outages.