Weeding Out the Weeds on Santee Cooper Lakes

Clean Lakeshore crested floating heart floating heart Hydrilla hydrilla control lake weed control Lake Weed Identification lake weed killer lake weeds water hyacinth

They say bad luck comes in threes, and that is the case on the Santee Cooper lakes this year. A trio of invasive weeds, including one still so new that the state hasn’t officially declared it such, has literally taken root and continues to hold on despite the best efforts of Santee Cooper’s analytical and biological sciences department. Invasive weeds are not new to Lake Moultrie or Lake Marion. But they are pervasive.

This year is the 30th anniversary of hydrilla first being spotted in the system, in Lake Marion near Rimini. By 1994 it covered almost 45,000 acres of the two lakes — roughly 40 percent of the water surface. Aggressive, hydrilla-eating Chinese grass carp were introduced to the lakes in 1989 and finally made a dent in the problem in the mid-1990s. Maintenance stocking of the sterile carp became more routine in the 21st century, but a combination of events has led to a resurgence in hydrilla the past couple of years. Today, it covers nearly 5,000 acres, a far cry from its peak but still alarming growth from a few hundred acres just three years ago.

A second nuisance plant is the deceptively delightful-sounding water hyacinth, which first emerged in the early 1990s and is currently blanketing almost 1,500 acres. That’s a larger presence than in recent years, due to the mild winter. “It’s been around awhile, but it’s easy to control,” says Larry McCord, supervisor of analytical and biological sciences. In other words, it’s out there and it’s the least of his worries. McCord knows he’ll eventually stamp down the hydrilla again, too. He’s battling a shortage of carp in the marketplace right now, but as he finishes out his plan to stock 109,000 of the fish in the lakes this year, they’ll go to work on the hydrilla.

It’s the third plant, the not-yet-designated invasive weed, that continues to thwart his team’s best efforts at eradication: crested floating heart. If the water hyacinth sounds nice, the crested floating heart looks nice. Think Monet’s Water Lilies, but easier to duplicate since it spreads so easily. In fact, the plant’s comely appearance is likely how it first found its way to the lakes, McCord figures. Probably a well-meaning resident thought it looked pretty in a container garden or somewhere else, pulled one up and transplanted it. The leaves can develop their own root structure though, and it can spread just by a leaf breaking loose and drifting or being pulled on a boat propeller somewhere else. McCord says the latest survey shows the crested floating heart is covering almost 3,000 acres of the lake now, up 50 percent in three years. It could easily spread to be as big a problem as hydrilla was two decades ago. Scientists haven’t found a fish yet that can eat enough of the weed to control it. So McCord uses chemicals which have limited effectiveness. Getting the plant declared invasive by the state might help secure additional resources to battle it and keep folks who think it’s pretty from moving it to their backyard lakeshore. McCord has been working on getting that declaration since 2005. There’s real money involved in the fight, too. Santee Cooper is spending $1.2 million this year battling invasive weeds on the lakes, part of our overall responsibility for managing the lake system to promote native habitats, recreation and inland navigation. McCord’s team tackles the weeds with truck, airboat and helicopter applications of EPA-approved chemicals, and he’s cornered the market on grass carp now in the ongoing hydrilla war. At best, that’s enough money to hopefully keep the problem from getting bigger, although the crested floating heart is gaining acreage right now. “I hope people out there will notify us if they see new areas of the weed,” McCord says. “I hope they’ll try not to spread it, and I hope they’ll be patient as we work to get rid of it.”

This article by Mollie Gore of Santee Cooper Corporate Communications from Santee Cooper’s Powersource magazine.

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