The free-flowing St. Croix River at Salmon Falls, just below the Milltown Dam, which will soon be demolished. Credit: Murray Carpenter / Maine Public

The St. Croix River, also known as the Schoodic River, flows through the homeland of the Passamaquoddy people between Maine and the province of New Brunswick. It once teemed with millions of migratory fish. Then came a series of dams that blocked the fish from their spawning grounds, and years of conflict over river management. But now the state of Maine, the Passamaquoddy tribes and government agencies that manage the river have formalized an agreement to protect the river and the fish.

Passamaquoddy drummers opened a formal signing ceremony in Calais this week with a welcome song.

Maggie Dana, chief of the Passamaquoddy Tribe at Sipayik, said the river is at the very heart of the tribe’s culture.

“Our people for thousands and thousands of years, have used this waterway for you know traveling, up and down the waterway to get to another community, fishing, sustaining ourselves,” Dana said.

But that fishing declined precipitously when dams blocked the river in the 1800s. Then in 1995, the state of Maine ordered fishways on two dams to be closed, because upriver fishing guides worried the alewives would harm populations of smallmouth bass.

Passamaquoddy tribal member Brian Altvater said that this caused the remnant fish run to plummet.

“In 2002, at the Milltown Dam here, between Calais and St. Stephens, they counted 900 alewives, 900 if you can think about it,” Altvater said.

Altvater and several others formed the Schoodic Riverkeepers to protect the river and restore the fish runs. A 2013 Maine law reopened the fishways, and Altvater said runs are improving.

“Last year we were well over 600,000 fish. You think about that, that’s quite a change, but estimates have put the number between 50 and 80 million fish can pass up this river if it was unobstructed, and that’s what it’s carrying capacity is,” Altvater said.

The fish will get more help because the lowest dam on the river will soon be demolished, but Altvater said that problems remain at fishways at upriver dams.

Sean Ledwin of Maine’s Department of Marine Resources said that when the Milltown Dam is removed, and fishways are improved at Grand Falls and Woodland dams, the run of alewives and blueback herring, which are collectively known as river herring, could become internationally significant.

“Just those three projects coming on, you could certainly see the biggest river herring run in the world,” Ledwin said.

The number of agencies and governments at the signing ceremony hints at the complexity of managing the river, estuary and bay that form the international border in eastern Maine.

Among those welcoming the spirit of cooperation is Lita O’Halloran, the conservation manager for the Peskotomuhkati Nation at Skutic, on the east, or Canada, side of the river.

“The great news is that everybody is coming here together to say ‘Yes we want to do work to restore this river, and we want to work together to do it, even if there’s a border in between that makes it difficult, we’re going to work together to make it happen,” O’Halloran said.

And everyone agrees the payoff could be big — many millions of alewives returning, and an ecosystem in recovery.

This story appears through a media partnership with Maine Public.