Cape Fear Fish Passage
CAPE FEAR FISHWAY - Removing Barriers to Upstream Habitat
NOAA Fisheries was involved in the design, study, and construction of a fishway at a dam which had been blocking access to historical spawning grounds on the Cape Fear River.
The Cape Fear River once supported a thriving migratory fish population including American shad, river herring, striped bass, Atlantic sturgeon, and shortnose sturgeon. Populations have declined substantially over the past two centuries due to poor water quality, overfishing, and blockages to historic spawning grounds near the Fall Line. The Fall line is a geologic feature where rivers descend quickly from the Piedmont to the Atlantic coastal plain, generally marked by waterfalls or rapids.
The most prominent obstructions evident today are the three lock and dams in the middle portion of the river basin constructed between 1913 and 1934 and operated by the U.S. Army Corps of Engineers. These lock and dams were built to promote commercial navigation on the river but now serve primarily to create pools of water for municipal and industrial uses. In August 2000, the Army Corps committed to construct a fishway, or a water-based ladder for fish to get passed the dam.
Lock and Dam No. 1 before and after construction of the fishway.
It was not until the American Recovery and Reinvestment Act of 2009 the Army Corps had the necessary funding to construct the fishway. The act required projects to be “shovel ready” in order to be funded and NOAA Fisheries was involved during all phases of the project including reviewing design plans, drafting monitoring studies, and overseeing construction. Construction started in the summer of 2011, and the rock-arch ramp fishway was finished in the fall of 2012. Efforts are underway for funding to a build rock arch ramps at Lock and Dam No. 2 and 3, which will allow complete access to the historical spawning areas.
Fall of 2011 showing partial completion of the fishway. A large scour hole, up to 45 feet deep, about 50 feet downstream of the dam needed to be partially filled before construction of the fishway could begin. Construction began at the eastern riverbank and then proceeded across the river to the navigation lock.
Satellite image of the partially completed ramp. This image shows the pools below the weirs.
Scientists from North Carolina State University have studied how American shad and striped bass use the rock-arch ramp fishway to apply these lessons learned to the Savannah River where a rock-arch ramp fishway will be constructed at New Savannah Bluff Lock and Dam. That project is being constructed to mitigate impacts to shortnose sturgeon from the Savannah Harbor Expansion Project.
Studies from 2013 and 2014 demonstrated that American shad numbers were significantly higher at the next upstream dam compared to years before the fishway was constructed. Over 60 percent of tagged shad passed up the ramp. However, striped bass success was lower than expected with less than 30 percent of tagged fish passing up the ramp.
Several Atlantic sturgeons have been seen near and in the lower part of the ramp but none have been observed using the ramp to go upriver however, in the fall of 2014, a large sturgeon was observed leaping below Lock and Dam No. 2. This is the first known occurrence of a sturgeon above No. 1 dam in recent times and whether it passed up the ramp or through a lockage is unknown.
A group of engineers, scientists, and natural resource managers, including the NOAA Fisheries, are discussing future work which might include moving some of the boulders to provide a more uninterupted flow through the rocks to increase the use of the ramp by striped bass and Atlantic sturgeon.
Completed fishway at a river flow of 1,000 cubic feet per second (cfs). Fish use the ramp by swimming between the rocks and resting in the pools at each tier before swimming between the rocks to reach the next level.
For more information about the Cape Fear Fishway Project: Fritz Rohde