HOWLAND, Maine — An infusion of $650,000 from the Nature Conservancy and the Atlantic Salmon Federation will help finish what has been called the “largest river restoration project in the country,” officials said Tuesday.

The Penobscot River Restoration Trust is using the money to clear debris from its $3.2 million fish bypass and the town-owned former Howland tannery site near Route 155, river restoration trust officials said. The work began last week. Once that work is finished, the historic $63.5 million restoration of the river will be complete.

The project is expected to deliver large-scale ecological, cultural, recreational and economic benefits throughout New England’s second largest watershed and has already begun to restore the river’s sea-run fish, the Penobscot River Restoration Trust stated in a news release. It also is

providing rippling benefits to wildlife along the river corridor and out into the Gulf of Maine, the trust stated.

“This project of local, national and global significance was reliant on a long-lasting partnership,” Kate Dempsey, state director for The Nature Conservancy in Maine, said in the statement. “So many have come together and recognized that this project is great for nature and for communities that depend on the river.”

A spokesman for the Atlantic Salmon Federation said the donation should help ensure increasing fish populations in the rivers and streams of northern Maine.

“As restoration of the Penobscot River is the top priority of the Atlantic Salmon Federation [ASF] in the U.S., we are excited to help meet the funding goal to complete the Howland bypass channel,” Bill Taylor, president of ASF, said. “By improving access to spawning grounds for Atlantic salmon and all the other sea-run species that are important to the river’s ecosystem, we are creating the conditions needed for these populations to rebound.”

This final funding will allow the completion of the Howland bypass channel this spring in time for the celebration of the conclusion of the entire project in June. The river channel around the Howland Dam is the last phase of a project that began in 2004. Dam owners, the state, the Penobscot Indian Nation, federal agencies and six conservation groups worked together, with broad community input, to implement the plan to restore sea-run fisheries on the river, while maintaining hydropower generation.

The project partners have raised what federation Vice President Andrew Goode estimated Tuesday to be $63.5 million in private and federal funds to implement the agreement that removed the Great Works Dam in 2011, the Veazie Dam in 2013 and has decommissioned the Howland Dam and built a new river channel around the old dam.

Simultaneously, the hydropower companies have increased energy generation at their remaining facilities and built a state of the art fish elevator at what is now the first dam on the river, the Milford Dam.