When did hydrilla hit South Carolina?

Hydrilla was first discovered in the Santee Cooper lake system (Lake Marion) in 1982, likely brought in on a boat trailer from Florida.

How did South Carolina control hydrilla in Santee Cooper?

In the 1990s, the state released massive numbers of sterile grass carp (over 700,000 fish). The carp were highly effective, eventually eating nearly all the hydrilla (and native plants) in the system.

Is hydrilla still a problem in SC?

Yes, while the original Santee Cooper infestation was knocked back, hydrilla continues to be managed in other major reservoirs like Lake Murray and Lake Wateree.

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Hydrilla in South Carolina: The Santee Cooper Story

Explore the history of hydrilla in South Carolina, featuring the dramatic boom and bust of the Santee Cooper lakes and ongoing management efforts.

The Santee Cooper Epidemic

The story of Hydrilla verticillata in South Carolina is dominated by the Santee Cooper lake system (Lakes Marion and Moultrie). When the invasive weed was discovered there in 1982, it exploded across the massive, shallow, nutrient-rich reservoirs.

By the mid-1990s, hydrilla covered over 40,000 acres of the system. While bass fishermen celebrated the incredible habitat (leading to record tournament catches), homeowners were landlocked, and the state-owned hydroelectric dams were severely threatened by floating mats of vegetation.

The Biological Solution

Faced with an infestation too large and expensive to treat with herbicides, South Carolina's DNR authorized one of the largest biological control experiments in US history.

The Stocking: Between 1989 and 1996, nearly three-quarters of a million triploid grass carp were stocked into the Santee Cooper system.
The Result: The carp effectively eradicated the hydrilla. However, because they are non-selective feeders, they also consumed nearly all the native submerged vegetation, fundamentally changing the ecology and fisheries of the lakes.
The Legacy: The Santee Cooper project remains a textbook case study in the power—and the blunt-force nature—of biological weed control.

Current Infestations

While Santee Cooper's hydrilla is currently suppressed, the weed has migrated to other major waterbodies across the state.

Lake Murray, a massive reservoir near Columbia, experienced a major hydrilla boom in the early 2000s, which was also met with a heavy grass carp stocking program. South Carolina continues to utilize a mix of herbicides, carp, and public education to prevent the spread of hydrilla fragments to uninfected piedmont and mountain lakes.

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Frequently Asked Questions About Hydrilla in South Carolina: The Santee Cooper Story

References

Information presented on this page is supported by peer-reviewed research, federal agencies, and state resource management programs.

U.S. Geological Survey (USGS) – Nonindigenous Aquatic Species Databasehttps://nas.er.usgs.gov
U.S. Army Corps of Engineers – Aquatic Plant Control Research Programhttps://www.erdc.usace.army.mil
NOAA Aquatic Invasive Species Programhttps://www.noaa.gov