For more than a century, a former hydroelectric station straddling Baltimore and Howard counties has blocked wildlife habitat and created unsafe swimming conditions on the Patapsco River.
That’s why wildlife and water quality advocates are cheering the destruction of Bloede Dam, a project that’s been more than a decade in the making and will kick off this month — with an explosion.
A rainy summer delayed the dam’s demise by a few weeks, but crews are waiting for a forecasted drop in water levels to blow up the dam and begin removing it in large chunks of concrete and rebar, a process expected to take about six weeks.
The first breach in the structure, just downstream of Catonsville and Ellicott City, could come as early as next week.
“It’s been a long time coming for this dam,” said Joanne Throwe, deputy secretary of the Maryland Department of Natural Resources.
Planning for Bloede’s removal began in 2011, but river advocates have been pushing for it since as early as 2006, and raising concerns about its ecological impact since the 1990s.
They gathered Wednesday on the banks of the Patapsco beside the dam to celebrate the $17 million demolition project.
“We look forward to seeing the rapids that have been hidden for over 100 years,” said Jim Palmer, president of the Friends of Patapsco Valley State Park.
The Bloede Dam opened in 1907 as one of the first of its kind in the world, built with power turbines beneath the concrete spillway that carries the river. But its technology became obsolete within a couple of decades.
Even after it stopped generating electricity, it continued to disrupt Patapsco River ecology. The dam blocks migration of fish such as river herring and shad, which live in the ocean but swim upstream to spawn. It also prevents passage of most American eels, which take a similar migration path, only in reverse, and also carry important species of freshwater mussels with them up the river.
Fish surveys below the dam show silver herring, hickory shad and some American shad migrating right up to the dam, but few of them made use of a “fish ladder” installed in the 1990s. Such systems are especially popular and high-tech in rivers along the Pacific coast, helping salmon make it upstream to spawn.
Ecologists hope the dam’s removal will open up 65 miles of the river and its tributaries for those species to escape predators and find more sources of food. Many of those streams will become accessible because Bloede is the latest Patapsco dam to be demolished, following the upstream Union and Simkins dams in 2010 and 2011.
“I just can’t wait to see the wildlife response,” said Wendi Weber, northeast regional director for the U.S. Fish and Wildlife Service. “It’s going to run fast and furious and beautifully.”
Flat, sandy sections of the river close to the Bloede are expected to transform relatively quickly into rocky rapids, their natural profile. That sort of river bottom also hosts more diverse communities of insects such as hellgrammites and stoneflies, important in the base of the food web.
“People are always amazed at how fast the rivers come back,” said Amy Kober, a spokeswoman for American Rivers, a national group that helped push for Bloede’s removal. “They heal themselves.”
Ben Grumbles, secretary of the Maryland Department of the Environment, compared reconnecting fragmented portions of the river to improving blood flow in parts of the body.
“It’s just like a circulatory system that brings more health to the overall body that we call the Patapsco River, and the Chesapeake Bay,” he said.
Apart from its ecological impacts, Bloede Dam has also posed a safety hazard on the river. The pool of calm water that collected behind it made it a popular spot for swimmers who reached it via the state park’s Grist Mill trail, but at least nine people have died at the dam in recent decades, most recently in 2015.
Work around the dam is expected to be completed by the end of the year, ending a nearly two-year construction project that has disrupted state park access. The actual dam removal is planned to start with a blast near the fish ladder structure on the Howard County side of the river, and end with hydraulic hammers breaking off the rest of the concrete from there toward the riverbank on the Baltimore County side.
How long it takes for river bottom and banks to transform will depend on how much rain comes after that.
Ecologists will be monitoring the impact on wildlife, eager to see how far some important species travel.
They could even make it all the way to the Daniels Dam, nine miles upstream on the main stem of the Patapsco and one of few remaining structures separating the tidal portions of the river from its headwaters, a northern branch that begins in northern Carroll County and a southern branch originating at Parrs Spring, at the point where Howard, Carroll, Frederick and Montgomery counties meet.
There is talk among river advocates about next turning their attention to removal of that dam, a popular spot for canoeing, said Serena McClain, director of river restoration for American Rivers.
“We’re all interested in looking at it, but we’re going to get Bloede out first,” she said. “Then, if fish make it all the way to Daniels like we expect them to, we’ll come knocking.”