Massachusetts Bay Transportation Authority (MBTA) Massachusetts Department of Transportation
Green Line Extension Green Line Extension


Notice of Project Change on Extension of the Green Line to Mystic Valley Parkway

On October 17, 2017, the MBTA filed a Notice of Project Change (NPC) for the Green Line Extension Project with the Executive Office of Energy and Environmental Affairs (EEA). This NPC was noticed in the November 8, 2017 edition of the Environmental Monitor. Comments were accepted by EEA until December 12, 2018. A copy of the EEA Certificate on the NPC can be found above.

You can read more about the NPC on the About this Project page, as well as see a list of local libraries that have copies of the document. If you have any questions, or if you would like to receive a hard copy of the document, please contact the Green Line Extension project team at

Environmental Assessment

Finding of No Significant Impact

  • Finding of No Significant Impact [4.2MB]
    MassDOT and the MBTA have received full federal environmental approval for the Green Line Extension project. The Federal Transit Administration released a Finding of No Significant Impact (FONSI) for the project, reaffirming the myriad environmental, mobility, economic development, and community-building benefits of the project. Federal environmental clearance is the culmination of several years of technical work done by MassDOT and the MBTA with close cooperation from the Cities of Cambridge, Somerville, and Medford, as well as the participation of hundreds of individuals and local organizations. The FONSI document contains a description of the federal environmental process, mitigation measures proposed for the Green Line Extension project, and an explanation of the public outreach efforts associated with the environmental process.
  • June 13, 2014 FTA FONSI Response Letter

The links below are the documents relating to the Green Line Extension Environmental Assessment. These file are large and may take some time to download.
If these documents are required in an alternative format, please contact the project staff.

EPA Brownfield Draft Documents

20 Third Ave - Vehicle Maintenance Facility Site 1

44 to 48 Third Ave - Vehicle Maintenance Facility Site 2

Ball Square Station:

Final Environmental Impact Report

Documents relating to the Green Line Extension Final Environmental Impact Report.

Draft Environmental Impact Report/Environmental Assessment

All documents relating to the Green Line Extension Draft Environmental Impact Report.

Selected Documents

Document Archives

Archive of documents provided for historical purposes, may no longer be relevant or accurate to the current state of the project.

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