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Thursday, 03 May 2012 01:44

Tuckasegee River revival: Demolition of Dillsboro dam restores aquatic life

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In the two years since the Dillsboro Dam was torn down, the Tuckasegee River has become home to a growing number of aquatic species, from mussels to insects to fish, as natural river habitat has been restored.

“We’re certainly glad that it’s gone,” U.S. Fish & Wildlife Service biologist Mark Cantrell said last week. “The response was immediate.”

Duke Energy demolished the 12-foot high, 310-foot long dam in February 2010 as environmental mitigation for several other larger dams it operates in the region. Jackson County battled for seven years to keep the dam. It wanted to make the dam a centerpiece of a new public park and promenade, complete with walking paths, benches, fishing areas and river access. Plus, the county argued the dam was historically important to the community.

Duke, however, succeeded in removing the small and ancient dam as compensation for using the Tuck in its lucrative hydropower operations, which net the utility millions annually.

Duke’s contention that the river would be better off environmentally without the Dillsboro dam does seem to have come true, according to Cantrell.

“What we’re seeing now is the rebirth of that section of river and a confirmation of the decision to remove it. There’s no question about it — if you are an angler, boater, fish or bug, the Tuckasegee River is better with the Dillsboro Dam removed,” he said.

Jackson County trout fisherman Craig Green said that he supported the removal of the dam and has been happy to see the river return to its natural free-flowing state.

“Recovery is a strange word — it wasn’t that things were bad, but clearly the dam removal has enhanced the flow for the fish to move back and forth,” said Green, who is a past president of the Watershed Association of the Tuckasegee River.


A tourist attraction

Cantrell described the physical shape of the former river as coming back in “a really impressive” manner.

The dam had turned a nearly mile-long stretch of the river behind it into a slow-moving backwater. The backwater was 310 feet wide — the same width as the dam — but the natural river bed is just 50 or so feet wide.

To Mark Singleton, a paddler in Sylva, the removal of the dam “was like unwrapping a big old Christmas present.” He couldn’t wait to see what the river’s natural contour would be like once it returned to its true form.

With the dam gone, boaters discovered a natural rock ledge below the surface where the dam used to be. The ledge doesn’t deter experienced kayakers, he said, but it is a bit too challenging for beginning boaters to use, so most bypass that section.

“It doesn’t get paddled a lot,” said Singleton, the director of American Whitewater, a national paddling and river advocacy group based in Sylva.

As part of the mitigation, Duke Energy was required to build a public river access just upstream from the former dam site. On one side of the river, there is a parking area, restrooms and a boat put-in. On the other side is a more primitive parking lot used mainly by fishermen.

James Jackson, owner of Tuckasegee Outfitters, said the removal of the dam and the subsequent growth in visitors coming to raft has been measureable. He estimated yearly business growth of 10 to 15 percent in terms of visitation.

“I think it is one of the larger tourist attractions in Jackson County,” Jackson said of rafting on the Tuckasegee.


The recovery to date

By removing Dillsboro Dam, river species that had vacated the mile-long backwater behind the dam have now returned.

“One of a dam’s great impacts on a river is changing the area behind it from a free-flowing river to a reservoir, typically unsuitable habitat for most native stream species,” Cantrell said.

Cantrell said the dam acted as a barrier for a number of fish species, some that needed to go upriver to spawn. The sluggish water previously held behind the dam also acted as a barrier to certain fish, he said.

Twice a year in 2008, 2010 and 2011, biologists such as Cantrell monitored fish and other aquatic life, providing a before-and-after picture of how dam removal affected the river, especially at the site of the former backwater.

A species considered foremost during dam removal discussions was the Appalachian elktoe, a federally endangered mussel found only in Western North Carolina and a sliver of East Tennessee. The elktoe did not exist in the pooled-up backwater behind the dam, but monitoring has now found more than 140 elktoe mussels in the stretch, a sign the previously bisected population will reconnect, strengthening its long-term viability.

Before removal, the reservoir area was home to a diminished variety of macroinvertebrates. These insects, crayfish, and other animals without backbones form much of the life in a stream ecosystem. Just more than a year after the removal, macroinvertebrate diversity had increased, on par with sites upstream and downstream of the reservoir site. Among macroinvertebrates, biologists often pay special attention to mayflies, caddisflies, and stoneflies, which tend to be sensitive to water quality and are indicators of stream health.

Following removal, the diversity of these three insect groups increased dramatically in the former reservoir area — from a monitoring low of only two types in October 2008 to a high of 40 in May 2011. Using macroinvertebrate numbers and diversity as a measure of stream health, their return lifted this stretch of river from a “poor” quality rating in 2008 to a “good” ranking in May 2011.

“It all seems to be right on track,” Cantrell said.

As expected, fish diversity has responded somewhat more slowly to the dam removal, though biologists have noted the fish community is shifting to one typical of a Western North Carolina river, and the number of fish species dependent on flowing water is increasing. Additionally, in May 2011, biologists found an olive darter, a species of conservation concern for state and federal biologists, upstream of the dam site for the first time. The discovery could mean the fish took advantage of the dam’s removal to expand its range into upstream habitat.

Biologists also made an encouraging discovery downstream of the dam site. For several days in 2008 and 2009, biologists scoured the river downstream of the dam searching for mussels. They uncovered 1,137 Appalachian elktoes, which were all systematically tagged and moved upstream, away from potential harm from the demolition.

“Regarding the health and well-being of the Tuckasegee River, removing Dillsboro Dam has been a success,” said Hugh Barwick, Duke Energy biologist who managed the dam removal and biological monitoring. “The removal was a positive step in improving aquatic life in the Tuckasegee River in the vicinity of the former dam and reservoir.”

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