In Chester County, S.C., near the North and South Carolina border—an hour’s drive south of the U.S. National Whitewater Center in Charlotte, N.C.—a new project is taking shape that will also attract paddlers and other river enthusiasts throughout the region, while bringing water to a section of river that hasn’t seen flows since 1907.
More than 100 years ago, the Great Falls-Dearborn Dam was built on the Catawba River for a hydroelectric plant, which created the popular Great Falls Dearborn Reservoir but also de-watered the 2.25-mile Long Bypass Reach below the dam. As part of the recent Catawba River Agreement and FERC dam re-licensing, a multi-million-dollar effort has been launched to return water to the river for recreation and restore aquatic life and lowland habitat downstream of the dam.
River recreation and restoration specialist S2O Design & Engineering was tapped to design a solution to allow flows through the diversion dam in a controlled manner and to provide safe bypass for paddlers who wish to traverse past the dam and into the beautiful corridor of eventual Class II-III whitewater. With construction now past the halfway point, water will soon be flowing down the Long Reach of the Catawba for the first time since 1907.
“This was an innovative approach to a complex challenge, and our team has been outstanding navigating the engineering, construction, environmental, and regulatory variables,” says Scott Shipley, S2O Design president and founder and a former kayak Olympian. “The results of this project will have a very positive impact on the health and vitality of the river and create exciting recreation opportunities for paddlers across the region.”
To accomplish the multiple objectives designers created two release points or notches in the dam for recreational release flows and boaters to navigate into the Long Bypass Reach — a Main Channel that will convey water continuously into the section; and a Recreation Bypass Channel that will provide a safe route for boaters during recreational releases.
The 400-foot-long Main Channel will take most of the flow down the eight feet of drop from the reservoir to the bottom pool, providing continuous hydrologic connectivity between the reservoir and the river. To accommodate boater passage, it incorporates three innovative multi-stage drop structures that help control flows through the channel at various levels without creating dangerous recirculating hydraulics.
To provide the safest possible passage to the section at higher flows, the Recreation Bypass Channel will have less drop over a longer distance. This 1,075-foot-long passage features nine adjustable drop structures to control the amount and intensity of flows in the channel, a recovery pool and island with gradually sloped sides, and portage trails for boaters to exit the channel if needed. The Bypass Channel is also designed to accommodate fish passage at lower flows. To build both, S20 worked with engineers at the Czech Technical University in Prague create a 1:20 scale physical model to study a range of flow conditions.
American Whitewater was also involved to represent paddling interests across the basin during the FERC relicensing process to open up this reach of the Catawba River to boating. These and other enhancements are part of ongoing efforts by Duke Energy in opening local lakes and rivers to recreational use. Construction on the Great Falls-Dearborn Diversion Bypass began in the spring of 2020 and is expected to be completed by fall 2022.