Let the rivers run through it

Dam removal in the Chesapeake watershed is restoring the area’s ecology

May 03, 2010|By Cindy Ross

My fishing buddy, Bob, is against the dam on our local stream being removed. In his mind, the spillway is a waterfall. To his eye, flat water, the wide lake behind the dam, is more aesthetically pleasing than a free-running stream. He does not want a dramatic change; he does not want the landscape altered.

Our rivers and streams have become so crowded with dams, many only a few feet high and 100 or more years old, that many people like Bob do not see the toll they have taken on fish populations, wetlands and the overall health of the stream.

"It is time to rethink our nation's infrastructure," says Rebecca Wodder, president of American Rivers. "Dam removals are an example of how our communities can reap huge benefits when we work with nature instead of against it."

Her organization has worked with state and federal agencies, citizen groups and others to educate people about he impacts of dams, and spearheaded the removal of hundreds of outdated dams around the nation.

Pennsylvania leads the country in river restoration, and many of these waterways lie within the Chesapeake Bay drainage. The Nicodemus Dam in the Antietam Creek/Potomac Watershed near Waynesboro and the Middle Spring Creek dam near Shippensburg are both slated for removal this summer. Further south, on Maryland's Patapsco River, removal of Union Dam is nearly complete, Simkins Dam is scheduled for removal in September, and Bloede's Dam near Ellicott City is planned for removal in the future.

The Patapsco River dam removals are of particular note, for it is American Rivers' goal to restore the entire waterway, allowing migratory fish such as the American eel to once again swim upstream without interference.

My angler friend doesn't realize that his beloved dam has unnaturally changed the habitat behind the structure and below it. Dams impede the flow of coarse gravel and sand, both of which increase channel complexity and improve habitat. Sediment-starved streams can become very uniform, with a profile that looks as if a wall parallels the waterway. A healthy river bottom has variety: rocks, sandbars, riffles and pools; it might not naturally be the same uniform depth all the way across.

Just because a dam has been there a long time doesn't mean it is good for the river. People functioned with a different set of values back when these dams were built. Many were created to power mills that no longer exist. Populations of shad and other migratory fish have declined, often drastically, in large part due to the thousands of dams that were built in East Coast rivers. Back then, species such as shad, herring and eels seemed too abundant to ever be placed at risk, and the overall health of the stream was not a consideration. If our forefathers had known that certain species would greatly decline and become endangered, perhaps they would have taken a different route.

Each dam removal project is evaluated on a case-by-case basis, but most dams are removed the same way: hydraulically jack hammered apart from the shore, piece by piece. Sometimes a causeway is built to work off of. Occasionally, a barrier is created upstream to divert the flow. Low water is the preferred time to take out a dam.

After the dam is removed, the stream is monitored yearly. Within only three months, there is usually a huge spike in the presence and health of insects — the macro invertebrate species that form a key part of the river's ecology. Dissolved oxygen, temperature and water chemistry also greatly improve.

My angler friend also isn't aware that some of these dams can be very dangerous. Eight lives have been lost at Bloede's dam because of swimming accidents. Kids slide down the "waterfalls" formed by dams or get pulled over the falls and become trapped at the base of these dams. Boaters who run these drops also risk their lives. Communities downstream face a risk the old dams will breach at high water.

Educating the public on issues such as these is a big part of what American Rivers does. Once a dam is removed and the disturbed earth greens up, the wetlands are restored, and the aquatic life and water quality improve, most agree that the dam removal was a good thing.

My friend Bob will be able to launch his fishing kayak on the river and paddle without portaging around a dam. Even Bob, who resists change, will see that a good thing, like his river, can get even better.

Cindy Ross lives in Pennsylvania and has written six books about the outdoors. This column is distributed by Bay Journal News Service.

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