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Wednesday, 10 February 2010 17:04

Going, going, gone

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When Duke first broached the idea of tearing down the Dillsboro dam eight years ago, Mark Singleton thought he would see this day come much sooner than it did.

A champion of dam removal both for the ecological and recreation benefits, Singleton had a front row seat last week on the banks of the Tuckasegee when a hoe ram struck its first blow, taking a tiny but symbolic chip from the top of the dam.

“It’s a historic day for the river. It’s also nationally significant,” said Singleton, a Jackson County resident and paddler. “Dams like this don’t come down very often.”

Singleton hardly slept the night before, wondering what the river would look like in its natural state. Before the dam came down, you could barely make out giant rock formations lurking beneath the surface. The dam was also rumored to sit on top of a rock ledge. That would all be exposed as the water dropped, revealing what Singleton hoped would be fodder for a paddlers playground.

“What kind of cool features are waiting under there?” Singleton said. “It is like Christmas. You are unwrapping a present.”

Singleton also wondered whether the large rock formations would create shallow tide pools, something his own children like to explore.

“All of that is underneath here. We just haven’t seen it in 100 years,” Singleton said.

Singleton said the former dam site will be a construction zone for a few months yet, but by summer, he hopes to be paddling down the new stretch of river. A big spike among paddlers could be witnessed the first year, but Dillsboro will likely find itself as a new hub for recreational paddlers even after the novelty wears off, said Singleton, the executive director of American Whitewater, a national paddling advocacy group.

“It is a great thing. I am glad to see the river is free-flowing,” said James Jackson, a local paddler and business owner. “I think it will be a great addition to the county.”

Meanwhile, environmental benefits of dam demolition were also cheered by biologists who had lobbied for dam removal.

For starters, nearly a mile of slow moving backwater behind the dam will be restored to a natural mountain river. Also, with the dam gone, fish will once again have free range to migrate up and downstream, expanding their reach, according to Mark Cantrell, biologist with the U.S. Fish and Wildlife Service.

Aquatic species have been “bumping their head on this dam for years,” Cantrell said.

One such species is the endangered Appalachian elktoe mussel. The eggs of elktoe mussles hitchhike on fish, which unwittingly play host to the developing larvae in their gills. The baby mussels eventually jump ship and wherever they land becomes their new home. Dams that block fish consequently block the distribution of the elktoe mussels.

Dam removal will allow previously isolated elktoe populations to unite and in turn build back up the gene pool, Cantrell said.

Dam removal will also help the sicklefin redhorse, an extremely rare fish that Cantrell would like to see placed on the list of endangered species. It is found on only five rivers in the world, all of them here in the mountains.

Like salmon, but on a smaller scale, the sicklefin redhorse swim upstream to spawn. But the Dillsboro Dam blocked them from doing so. Removing the dam will it allow access to new spawning grounds.

The sicklefin redhorse traditionally returns to where it hatched to spawn. Since the fish currently aren’t found upstream of the dam, it could take generations for them to discover the new territory if left to their own devices.

But Fish and Wildlife biologist have lent a helping hand by rearing sicklefin redhorse in captivity and releasing newly hatched fry upstream of the dam every year, imprinting the fish to return to the same spot one day when laying eggs of their own.

The sicklefin redhorse don’t spawn until the fifth year of their life, but the biologists are now in the fifth year of the releases — with a total of about 5,000 released over that time. Within a year, the first of those imprinted fish should reproduce naturally on sections of the Tuck upstream of Dillsboro, giving rise to a new population of the threatened sicklefin.

U.S. Fish and Wildlife has conducted species assessments above and below the dam, and will watch eagerly to see if the numbers and diversity increase in the years following dam removal.

“This is what it is all about,” Cantrell said. “The intent of dam removal is to see these environmental benefits.”

 

As the dam came down

While the river ecology will improve over the long run with the dam down, biologists were concerned about immediate impacts of chunks of the dam and backlogged sediment washing downstream during the demolition process. While Duke was required to dredge some of the sediment prior to demolition, a lot still remained.

“As the water levels drop, we will see some of that sediment that was previously sequestered behind the dam be redistributed downstream,” said Cantrell, whose agency is monitoring ecological issues in the Tuck before, during and after dam demolition.

A large cloth net was strung across the river to strain out debris coming down, but it wasn’t a catch-all.

So water monitoring stations were set up above and below the dam to measure sediment during demolition. If sediment levels got too high, the rate of demolition could be slowed. Another tactic would be releasing more water from Duke’s other dams higher up the river to dilute the ratio of sediment in the water being flushed downstream, Cantrell said.

Safety precautions were also in place, including a lifeline strung across the river should a worker fall overboard, and a motorized lifeboat moored at the river bank to go after someone.

 

What’s next?

As onlookers watched the water level drop last week, they braced themselves for the ugly scene that would be revealed: a giant, barren pit of mud and muck stretching along the riverbanks.

Duke is supposed to do steambank restoration to kick-start revegetation, and it’s something both the community and biologists hope Duke will do well.

Duke is working on a massive landscape plan to revegetate the banks, according to Hugh Barwock, the project manager for dam removal and a senior environmental resource manager for Duke out of Charlotte.

TJ Walker, owner of the Dillsboro Inn, is keeping his fingers crossed that Duke does a good job with streambank restoration. For now, the view from his inn on the banks of the Tuck is that of a fresh mud flat. But Walker says the project manager has promised it won’t look that way for long.

Walker initially fought dam removal, but backed down a couple of years ago.

“My sense of abandonment is replaced with a sense of hope,” Walker said last week.

 

Want to learn more?

The Fish and Wildlife Service has created a Web site dedicated to removal, including demolition photo and facts of environmental benefits at www.fws.gov/asheville/htmls/projectreview/DillsboroDam.html

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