By Dave Russell
The dam that holds back the East Fork of the Tuckaseigee River to form Cedar Cliff Lake in the Canada community will undergo a facelift in coming months when its auxiliary spillway is re-worked.
Part of that work could involve the dumping of rocks and soil into the lake.
The Federal Energy Regulatory Commission required Duke Energy to make modifications to ensure the safety of the dam during extreme high-water conditions, Duke spokeswoman Kim Crawford said.
The spillway upgrade project includes deepening and widening the existing auxiliary spillway channel and replacing the two fuseplugs with a fusegate system, according to the engineering report.
A fuseplug is a collapsible dam installed on spillways in dams to increase a dam’s capacity.
Fusegates provide a controlled release of water during large floods. In large flood conditions they topple forward, allowing a controlled flow of water.
The existing spillway width will increase from 95 feet to 145 feet, and the channel bottom will be lowered by 15 feet on average.
“We are modifying the existing auxiliary spillway channel, installing a new gate system and installing a concrete wall along the crest of the dam,” Crawford said.
Site development work got underway in late 2019. This included constructing a new bridge across the primary spillway channel, refurbishing the primary spillway gate and its hoist, establishing laydown areas, tree clearing, improving access roads and performing work at the boat ramp.
“The next – and primary – phase of construction will begin first quarter 2021,” Crawford said. “This includes widening the auxiliary spillway, primarily by blasting, installing the new fusegate system, and refurbishing the crest of the dam, including adding a concrete wall.”
The project includes the placement of the excavated material – soil, weathered rock and rock – generated by grading into a designated area of Cedar Cliff Lake.
The placement of excavated materials in the lake is in compliance with authorizations and permits issued by FERC, the U.S. Army Corps of Engineers and the State of North Carolina, Crawford said.
“Our 404/401 permit from the U.S. Army Corps of Engineers approves the placement of excavated material into a designated area of the lake,” she said. “It does not specify or limit the volume. We estimate the volume of excavated material at approximately 300,000 cubic yards.”
A lake drawdown plan and environmental report, including a water quality monitoring plan, was prepared in 2018, reviewed by state and federal resource agencies and authorized by the FERC. The construction work at the site is being conducted in accordance with the approved engineering designs and permits, Crawford said.
The Tuckaseigee River, part of the Mountain Heritage Trout Waters program, a cooperative effort between the N.C. Wildlife Resources Commission and local governments, is not in danger from the dumping, she said.
“The permits require compliance with state water quality standards to protect the lake and the river downstream,” Crawford said.
Placement of natural materials in reservoirs has been used to improve fish habitat. Over the past few years, the N.C. Wildlife Federation has received grants to create a rock reef in Lake Norman, Crawford said.
Not everyone is convinced.
“Tuckaseigee Trout Unlimited would certainly go on record as opposing the dumping of any kind of sediment that’s going to come down the Tuckaseigee River,” President Tommy White said. “It’s already in bad enough shape from everything that happened on the Western Carolina University campus this year. We don’t need more sediment in the river.”
Sediment from an apartment complex, a public/private partnership on WCU’s Millennial Campus, seeped into a tributary of the Tuckaseigee and also caused a landslide that knocked a house off its foundation.