Lake Norman is the largest reservoir in the Catawba River Basin (~32,000 acres). Hydrilla was reported in 2017 and the infestation is currently being managed. This is the second Hydrilla outbreak the lake has experienced. The first occurred in 2002. That original infestation was aggressively managed with triploid (sterile) grass carp. Grass carp are herbivorous fish used in many states to control the growth of aquatic vegetation. By 2004 the approximately 400-acre Hydrilla infestation was fully suppressed. Relatively small numbers of grass carp were released in the years that followed. This strategy effectively continued the suppression of Hydrilla and ultimately it was eradicated from the lake.
Since that time Hydrilla was again introduced to Lake Norman. That introduction went undetected for several years and the infestation had expanded to ~500 acres by 2017, and then to ~640 acres in 2018. This infestation is unrelated to the initial outbreak (circa 2002) and fairly isolated to the Ramsey Creek area. The epicenter of the infestation is the Blyth Landing public boat access. The infestation is likely due to a “hitchhiker” introduction. This is when equipment (trailers, boats, gear, etc.) is transported while contaminated with weed fragments and/or propagules. Because of improper boat/equipment cleaning, invasive aquatic weeds, such as Hydrilla, are spread from infested areas to other bodies of water.
Beginning in the spring of 2018 an aggressive management approach was implemented. Following the success of previous management, triploid grass carp were selected as the primary management tool and 10,200 carp were released. In April 2019 an additional 12,330 triploid grass carp were released. The combination of these two large releases led to the complete suppression of Hydrilla growth during the 2019 season.
This project is a partnership between NCDEQ, Lake Norman Marine Commission, Duke Energy and Charlotte Water.
For more information about this aquatic weed, see our document on Hydrilla.