Hydroelectric dams are crucial for producing electricity, but the natural flow of a river is also altered, and access to upstream habitat, which is vital for migratory fish species, is restricted.
A portion of the Roanoke River that had been cut off for fifty years had its flow restored eighteen years ago by NOAA Fisheries and partners.
The population of resident fish, particularly the American eel, is steadily increasing here, according to long-term monitoring.
Freshwater mussels, especially species that are extremely fragile, are also starting to thrive. It's interesting to think that the unexpected rise in these mussel populations may be related to American eels.
The Roanoke Rapids Dam
(Photo : Gabor Koszegi)
In 1955, the Roanoke Rapids Dam was constructed.
Since then, the majority of downstream flows have been routed through a conduit that transports water away from the powerplant by the dam operators, as per NOAA.
This stopped the river from flowing through a 331-acre area next to the canal, which later came to be known as the bypassed stretch.
Dominion Energy was granted a new license by the Federal Energy Regulatory Commission in 2004 to run the hydroelectric project.
In order to enhance fish passage at the dam at the time, NOAA Fisheries and collaborators asked that flow be restored to the bypassed reach.
The largest and least-affected bottomland hardwood forest habitat is still present in the mid-Atlantic area in the floodplain of the Roanoke River.
While the lower portion of the Roanoke River is home to extensive bald cypress and water tupelo swamp forests, the middle part is distinguished by alluvial forests and back swamps, as per The Nature Conservancy.
More than 200 different bird species may be found in the Roanoke River, which is home to a wide variety of other plants and animals.
Species of plants and animals have adapted to the Roanoke River's floods over thousands of years.
However, three dams, including John H. Kerr, Gaston, and Roanoke Rapids--located close to the Virginia-North Carolina boundary have drastically altered the river during the past 50 years.
In compliance with the requirements of the new license, Dominion Energy reinstated flow to the bypassed reach in 2005.
Operators discharge a minimal continuous flow over the dam's spillway and into the reach in order to sustain downstream flows throughout the year.
They also release extra flows up to three times the minimum at specific times of the year. This facilitates anadromous fish species' upstream movements, particularly for American shad, river herring, and sturgeon.
Only when the dam is actively pouring water can the bypassed reach experience higher flows comparable to natural river conditions.
This occurs as a result of river floods, higher flows from upstream dams, or project maintenance. These substantial floods often take place numerous times during the year.
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Thriving of species in the dam
In compliance with the requirements of the new license, Dominion Energy reinstated flow to the bypassed reach in 2005.
Operators discharge a minimal continuous flow over the dam's spillway and into the reach in order to sustain downstream flows throughout the year.
They also release extra flows up to three times the minimum at specific times of the year. This facilitates anadromous fish species' upstream movements, particularly for American shad, river herring, and sturgeon.
Only when the dam is actively pouring water can the bypassed reach experience higher flows comparable to natural river conditions.
This occurs as a result of river floods, higher flows from upstream dams, or project maintenance. These substantial floods often take place numerous times during the year.
Freshwater mussel populations have significantly risen almost two decades later. Because they graze on filters, mussels are crucial for preserving the water quality in natural river systems.
Since the previous study in 2016, certain mussel species' populations had increased by more than ten times.
The most prevalent species of mussel in the area is now the northern lance, which North Carolina resource officials classify as "very uncommon."
Possible contributors to the unexpected rise in mussel populations include American eels. Eels' gills are used by mussel larvae to move to new environments.
More proof that the initiative had a good effect on the Roanoke River may be seen in the rise in freshwater mussel abundance.
It also emphasizes the significance of ongoing observation in assessing the efficacy of restoration initiatives.
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