STATE HOUSE NEWS SERVICE

The Federal Transit Administration plans to provide nearly $1 billion in funding for the $2.3 billion Green Line Extension project, which will bring trolley service through Somerville to Medford.

Acting FTA Administrator Therese McMillan wrote to a US Senate committee on Monday, informing members that the federal government planned to provide $996 million in a New Starts grant.

The remaining funding for the 4.7-mile project would include $996 million in state bonds and $305 million out of the state’s operating funds, according to the letter from McMillan.

The rail extension has been many years in the making and is required as a stipulation of the Big Dig highway project in Boston.

In a statement, MBTA General Manager Beverly Scott said the extension is “among the most important transit projects in the nation.”

“I’ve expected this to be built now for 30 years. So expectations are one thing; realities are another,” said Congressman Mike Capuano, a Somerville Democrat, who was not surprised that FTA plans to move forward with the project.

The federal grant is undergoing a 30-day congressional review, and FTA officials will not sign the full funding agreement until that window passes, which would be around the New Year.

Capuano said the 30-day window is a “formality” and said Congress does not block New Starts grants. He said the FTA’s standards are “pretty high,” and not all projects are approved. Capuano said the New Starts grant is the last federal component of the project.

“Having action on the New Starts grant at this time is a cause for joy,” Rep. Denise Provost, a Somerville Democrat, said. Provost said she and other members of the delegation plan to meet with state transportation officials Tuesday, and she plans to ask about the use of operating funds to finance the project.

The project would relocate Lechmere Station in East Cambridge and construct six new stations through Somerville and into Medford, including a spur to Union Square. Additionally the project includes construction of a maintenance facility, a community path and the purchase of 24 new trolleys.

Gov.-elect Charlie Baker “has no plans to change course on this important project,” said Baker spokesman Tim Buckley.

Scheduled to open June 29, 2021, the project would create about 840 design and construction jobs, and 140 operation and maintenance jobs, according to the FTA letter.

The $2.3 billion project’s costs include debt service payments, according to MBTA spokesman Joe Pesaturo, who said those debt costs hadn’t been calculated into the earlier cost estimate of the project of about $2 billion. He said the debt service would be paid out of the operating budget.

Former Gov. Mitt Romney settled the Conservation Law Foundation lawsuit that created the legal requirement to construct the trolley extension.

The FTA estimates the extension will be used for 37,900 daily linked trips.

In October, the MBTA had a record-breaking month for ridership, with about 1.3 million using the transit service on a typical weekday.