LOWELL — A new report lists the Merrimack River among the nation’s top 10 endangered rivers, facing threats from upstream developments in Southern New Hampshire.

The American Rivers report ranks the Merrimack River at number 8, stating that a projected 40 percent to 63 percent of the forested land in the river’s watershed will be developed by 2030.

The loss of those trees could jeopardize the clean drinking water that serves more than 600,000 people, including those in Lowell and Tewksbury, according to the report.

“When you lose those trees, you lose them acting as nature’s Brita filter that helps suck the pollution instead of running into the river,” said Caroly Shumway, executive director of the Merrimack River Watershed Council.

Trees also help retain water, preventing it from running into storm drains and causing flooding, Shumway said.

The loss of forests could also reduce the habitat for threatened and endangered species.

The threats from deforestation stem especially from Southern New Hampshire, the most rapidly developing part of the state, according to the report.

Development in Southern New Hampshire has been picking back up over the last couple of years, according to Jack Munn, chief planner for the Southern New Hampshire Planning Commission.

One factor, he said, is the Interstate 93 corridor and the transportation accessibility to Massachusetts and other parts of the state.

The annual American Rivers report spotlights rivers at a critical juncture that could be saved with the proper action.

The American Rivers group is calling for the U.S. Environmental Protection Agency to create a bi-state watershed partnership to facilitate land protection and smart planning.

“One of the remedies is making sure that we have protection policies in place so there’s adequate buffers around the rivers that remain forested,” said Liz Deardorff, director with the American Rivers Clean Water Supply Program.

The 115-mile Merrimack River, which runs from Franklin, N.H., to Newburyport, has come a long way since its history as the polluted river that served as the pulse for the Industrial Revolution.

Since the passage of the Clean Water Act of 1972, the river has seen improvements.

That includes a 76 percent reduction in phosphate from 1965 to 2015 and a 38 percent reduction in nitrate, according to the Merrimack River Watershed Council.

The EPA has also advocated for the watershed’s conservation, supporting the Natural Resources Conservation Services that has protected over 8,000 acres with over $500,000 worth of contracts, according to the EPA.

The regional Merrimack Conservation Partnership, which includes groups in New Hampshire and Massachusetts, also works to preserve the watershed. Yet the study notes that the group lacks adequate funding.

The partnership received $225,000 worth of private grants for “transactional expenses” such as appraisals and surveys of land, said partnership coordinator Brian Hotz.

But those are not expenses that go toward actually purchasing land for conservation.

“Having the river designated like this is something that really I think is good for us,” he said. “Because it really focuses all of our organizations to doing more and looking beyond our individual organization, and trying to work together to truly make a difference.”

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American River Group’s Endangered Rivers of 2016

1) Apalachicola-Chattahoochee-Flint River Basin in Alabama, Florida and Georgia

2) San Joaquin River in California

3) Susquehanna River in Pennsylvania and Maryland

4) Smith River in Montana

5) Green-Duwamish River in Washington

6) Pee Dee River in North Carolina

7) Russell Fork River in Virginia and Kentucky

8) Merrimack River in Massachusetts and New Hampshire

9) St. Lawrence River in New York

10) Pascagoula River in Mississippi and Alabama.