Duke starts dredging above Dillsboro Dam
Duke Energy has begun work preparing a site along the Tuckasegee River upstream of the Dillsboro Dam in order to start dredging the river there.
While virtually everyone agrees the dredging is a good thing in and of itself, the fact that it is a prerequisite to tearing down the dam next year leaves all aspects of the project mired in controversy.
A site adjacent to the river along the slow-water pond created by the dam was cleared on July 1. It will be used as a staging area for siphoning out sediment backlogged behind the dam. A series of settlement ponds will separate sediment from the river water, allowing increasingly smaller particulate and fine organic matter to settle out before water flows back into the river.
An estimated 100,000 to 120,000 cubic yards of sediment have accumulated behind the Dillsboro Dam. Duke was mandated by the state to remove at least 70,000 cubic yards before it can tear down the dam to keep the sediment from washing downstream.
The dredging “is something they should have been doing for years,” said John Boaze, a biological consultant with Fish and Wildlife Associates and an opponent of dam removal. And, “I hope that when they get it done in Dillsboro they’ll move to Bryson, Lake Emory in Franklin, Mission over in Clay County,” Boaze said, listing some of Duke’s other dams that also have backlogged sediment behind them.
Boaze is concerned that Duke only has to remove 70,000 cubic yards rather than all of it.
“From the river’s standpoint, removing the sediment would be a good thing. They should remove it all,” Boaze said. Boaze said there was no basis for the state to arrive at 70,000 cubic yards as the magic number.
Kevin Barnett, an environmental specialist for surface water in the state Division of Water Quality’s Swannanoa’s office, said he thinks 70,000 cubic yards is sufficient to protect downstream water quality when the dam is removed. Barnett’s concern, however, is making sure sediment doesn’t end up getting transported downstream during the dredging process itself.
“The number of cubic yards removed is less important as opposed to how much material is transported downstream that would negate the intended effect of the work,” Barnett said.
To ensure this, Barnett said he would be checking — and Duke would be regularly reporting — on turbidity both upstream and downstream of the dredging work in order to monitor downstream deposition of sediments.
At the dredging site, Duke corporate spokesman Andy Thompson in Charlotte said the endangered Appalachian elktoe mussel could benefit from the dam’s removal, as upstream and downstream colonies would be able to mingle and create a larger, more viable population.
“I don’t really go along with that theory. We’ve already got mussels upstream and downstream,” Boaze said. “You’re going to mostly kill the ones downstream” due to habitat disruptions from the dam’s removal, no matter how carefully done.
Boaze said a better idea is to leave the dam but to create bypass waterways alongside it.
“I have a design: a fish passage put in place allowing them to go upstream and downstream, and kayakers to go downstream,” Boaze said.
Duke initially said they would do the dredging as part of the dam-removal plan if they could find a market for the sediment to offset the cost. But heightened attention to the project led the state to end up requiring the dredging.
All for naught?
The removal of the dam is in question, however, as Jackson County has moved to condemn the site. Jackson would like to seize the dam and adjacent shore to create a river park, which would serve as a scenic and recreational attraction. Jackson would also like to operate the dam as a form of green power.
Asked why Duke is proceeding with the dredging when it might be blocked from removing the dam, Thompson said Duke is confident the attempted condemnation will fail.
“It does not appear to Duke that Jackson County would be allowed by the applicable laws to condemn the Dillsboro Hydroelectric Project,” Thompson said. “Under the Federal Power Act, a hydroelectric plant can only be condemned by a county or municipality for the generation of hydroelectricity.”
Thompson added that state law does not provide for the use of condemnation to acquire a hydroelectric facility for power generation purposes. He said Duke “will certainly vigorously oppose any attempt by the county to condemn the Dillsboro Dam.”
County Manager Ken Westmoreland wasn’t concerned about Duke going to the trouble and expense of doing the beneficial dredging even while they might end up being prevented from removing the dam.
“The dredging is overdue. They should have been doing it under their previous license,” he said. “Our position is they’re simply doing it in compliance with their existing license — that they’re obligated to do periodic cleaning and dredging at all of their facilities.
Despite the dredging, Westmoreland says nothing is a fait accompli.
The removal of the dam is still very much in question,” Westmoreland said.
The proposed dam removal arose as a compensatory move by Duke in exchange for renewing federal permits for power-generating dams on other rivers throughout the region.
Removing the Dillsboro Dam to restore the section of the Tuckasegee to free-flowing status was offered by Duke as a benefit in exchange for the impacts of the other dams. However, the county and some area residents prefer to retain the historic dam. Other critics say dam removal does not serve as adequate mitigation, particularly for Duke’s dams on other rivers.