BRADLEY, Maine - When the steel claw of an excavator slashes into the berm of the Great Works Dam on Monday morning, it will mark the start of a multimillion-dollar project to allow endangered and dwindling species to return to their historic spawning grounds along Maine’s longest river, the Penobscot.

When the project is done - scheduled for 2015, after an additional dam is razed and another bypassed - it will open access to 1,000 miles of habitat for the native fish, including endangered Atlantic salmon and short-nosed sturgeon that journey from the Gulf of Maine to breed in the cold, fresh waters of the Penobscot. That is more than any dam removal and river restoration effort in the country, state and federal officials say.

People who had been fighting each other for many decades set that aside to focus on the common good,’’ said Laura Rose Day, executive director of the Penobscot River Restoration Trust, which bought the dams for $24 million two years ago and is overseeing their demolition. “It’s among the nation’s most comprehensive projects, with tribal, national, state, local, and nonprofit groups coming together to totally reconfigure the power production on a river so we can have fish restoration and hydropower.’’
The project, estimated to cost $62 million, will allow six other dams that will remain on the Penobscot and its tributaries to produce more electricity. Together, they will generate an estimated 50 megawatts of power, enough for about 25,000 homes.
“We absolutely see this as a positive - from a business standpoint and to satisfy our environmental responsibilities,’’ said Scott Hall, a spokesman for Black Bear Hydro Partners of Milford, Me., which owns the remaining dams.
Environmental advocates, fishermen, and a host of local, state, and federal officials have spent years seeking to restore the free flow of the Penobscot, the second-largest river in New England. 0ver the decades, as the dams churned out electricity, many of the river’s fish have disappeared.
After collecting data fisheries worker Ethan Lamb handed off an Atlantic salmon to Brian Probert, who prepared it for transport to a hatchery.FRED FIELD FOR THE BOSTON GLOBE
After collecting data fisheries worker Ethan Lamb handed off an Atlantic salmon to Brian Probert, who prepared it for transport to a hatchery.
Like other rivers in the region, such as the Kennebec, Androscoggin, Merrimack, and Connecticut, the Penobscot had massive fish runs until the early 1800s, when the nation began installing dams and log drives, mill waste, and other pollution began making many rivers into the equivalent of industrial dumps. There were as many as 100,000 salmon, 6 million American shad, and some 20 million river herring that migrated every year from the ocean to well north of Bradley to spawn.
There are now fewer than 1 percent that many fish of most of the 11 species that inhabit these waters, with less than 500 salmon counted this year, environmental advocates say. Most were bred in a hatchery. For years, the advocates prodded dam owners to build better fish ladders to allow the salmon to cross safely. But they found improved fish ladders didn’t do enough. The only answer, they decided, was to remove the three dams in the river’s lower 10 miles.
“The salmon population is now on life support, and it’s a miracle that we’re still finding all species that historically inhabited the river,’’ said Andy Goode, vice president of the Atlantic Salmon Federation in Brunswick, noting that many salmon die while trying to pass through the dams. “We think this is the last best chance to save the Atlantic salmon from extinction. They’ve already been lost on many other rivers.’’
After dismantling the 1,000-foot-long Great Works Dam, which until recently continued to generate power for a large pulp mill on the banks of the Penobscot, contractors over the next three years will raze the Veazie Dam, 7 miles downstream, and decommission the Howland Dam on the Piscataquis River, a tributary 22 miles upriver. The river there will be diverted into a fish-friendly bypass channel. Those three dams have been particular barriers to fish migration.
The final part of the project will be an elevator-like fish lift, which will be built by the Milford Dam, a few miles upstream from Great Works.
A dump truck was used to build a road into the Penobscot River on the Bradley-Old Town line for hauling away the Great Works Dam after it is dismantled.
FRED FIELD FOR THE BOSTON GLOBE
A dump truck was used to build a road into the Penobscot River on the Bradley-Old Town line for hauling away the Great Works Dam after it is dismantled.
“In addition to Atlantic salmon, this project will have an incredibly large benefit for other species that are economically important to the region,’’ said Eric Schwaab, acting assistant secretary for conservation and management of the National Oceanic and Atmospheric Administration, which has provided most of the money for the project. “This is a true ecosystem restoration . . . and will help bolster the entire Gulf of Maine.’’
Striped bass, blue-backed herring, alewife, sea lampreys, and other species will gain from having more habitats and spawning grounds. Marine life, such as cod and lobster, will benefit as they feed on other species and their eggs, and an increase in the larger fish will be a boon to eagles, osprey, and other birds that prey on them. The project comes a little more than a decade after the federal government ordered the demolition of the Edwards Dam on the Kennebec, the first such federal order for the benefit of fisheries. The controversial decision launched a wave of dam removals around the country.
Over the past century, 1,111 dams have been removed in the United States, more than half of them since the Edwards was dismantled in 1999, said Amy Kober, a spokeswoman for American Rivers, a Washington-based conservation organization that protects and restores rivers. She said about 75,000 dams remain in the country, 14,200 of them in New England.
“The Penobscot is one of the most significant river restoration projects our country has ever seen, because of the scope of benefits - access to 1,000 miles of fish habitats as well as the tribal, economic, and the recreational benefits,’’ Kober said. “We haven’t seen that much access before.’’
Among the beneficiaries are members of Penobscot Nation, which has a reservation on an island in the middle of the river near the Milford Dam. The historic fish runs long had cultural and nutritional importance for the tribe.
“This watershed has provided the means for survival for tribal members for thousands of years,’’ said John Banks, the tribe’s natural resources director. “We feel this project is somewhat precedent-setting in that it brings folks together from diverse backgrounds and interests to restore the ecological values of this river, while maintaining generating capacity. So it’s really a win-win for everybody.’’
But some residents in the area are skeptical about the promised benefits of the project. They have questioned whether the fish will really return, given how low their numbers already are, and worry what will happen to their property lines as water levels change.
“A lot of folks are just anxious about how this will all turn out,’’ said Melissa Doane, town manager of Bradley, where 1,500 people live beside the river. “But we’re excited that the project is finally getting started. A lot of us thought it would never happen.’’
In recent days, massive hauling trucks have deposited hundreds of tons of granite into the river water to create a path for the excavators to do the work of tearing down the mix of concrete, wood, and boulders that make up the large dam.
State and federal officials, including US Interior Secretary Ken Salazar, will be in Bradley on Monday to witness the first breaches of the barrier. Contractors expect the river will run freely here by the end of the summer.
“It’s an honor to take this down,’’ said Patrick Jordan, whose company is doing the work. “This starts a new era here.’’
David Abel can be reached at dabel@globe.com. Follow him on Twitter @davabel.