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Aquatic Weed Management Program
For more than 15 years CMUD has collaborated with Duke Energy, N.C. Department of Environment and Natural Resources (NCDENR), and the City of Gastonia to reduce and manage the invasive aquatic weeds Brittle Naiad and Hydrilla that were growing rapidly within our shared source waters, Lake Norman and Mt. Island Lake.

Hydrilla was of particular concern, as it can double in size every 14 days. As the coverage spreads, water quality grows increasingly impaired and weeds can clog filters and mechanical works through which we treat the communities’ drinking water.

CMUD’s Water Treatment Superintendent, Water Quality Lab Manager and Biologists from Duke Energy came up with the idea to stock the lakes with triploid grass carp. This biological control measure allows for the greatest control, least environmental impact and lowest cost compared to mechanical harvesting or herbicidal treatment.


These non‐native grass carp are sterilized so they can’t reproduce, and they are voracious eaters, consuming up to their body weight in vegetation each day.

The state paid half of the cost to stock the fish through their aquatic weed program, and CMUD, Duke Energy, and City of Gastonia officials split the remaining half evenly to support the program and preserve the quality of the source water. Because some of the sterile fish die off naturally or through animal/fishing activity, one‐third of the initial population must be re‐stocked each year. Generally the fish have a life expectancy of 10‐12 years.

There were approximately 1,500 combined acres of vegetative growth in the two lakes when the program began. Over the years, the vegetative growth has continuously declined in number of acres, and a recent Duke Energy survey showed Mt. Island Lake doesn’t currently have any appreciable vegetative growth. CMUD and its partners will continue to monitor and manage the 1,500 acres so the hydrilla tubers in the lake bed will not sprout and produce the vegetative growth and multiply.