Santee Cooper Lakes Giant Cutgrass Control Project

In 2016, the South Carolina Waterfowl Association expressed an interest in controlling the amount of giant cutgrass on the Santee Cooper Lakes (Lake Moultrie and Lake Marion) in collaboration with the South Carolina Department of Natural Resources (SCDNR), Santee Cooper and the United States Fish and Wildlife Service (USFWS). The 4,300 acres of dense giant cutgrass stands around the two lakes proved troublesome for those who tried to access the lakes for boating, waterfowl hunting, and fishing. These stands of cutgrass also choked out valuable fish spawning areas and made it difficult for native plants that are beneficial to waterfowl to flourish. The end result was a significant reduction of quality fish and waterfowl habitat on the Santee Cooper Lakes system. The 3,300 acres around Lake Marion and 1,000 acres around Lake Moultrie desperately needed to be scaled down and maintained to allow the growth of beneficial vegetation. SCWA was pleased to donate $10,000 toward the project with confidence that the plan would enhance habitat and the experiences for waterfowlers and fishermen.

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These photo are examples of targeted areas for the project that were inundated with cutgrass. Credit: Casey Moorer

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Chris Page with SCDNR’s Aquatic Invasive Species Program relayed, “The major goals of the project are to improve wildlife habitats for hunting, fishing, and other recreational opportunities within the Santee Cooper lakes system, as well as overall lake access.” Santee Cooper staff used GIS software to map out the problem areas in order to effectively execute the aerial operation, with treatment being conducted by Summit helicopters. All aerial applications of Environmental Protection Agency approved herbicides were done with a spray rate of 20 gallons per acre to ensure adequate coverage and efficacy. For the year of 2016, Santee Cooper sprayed 308 acres of cutgrass, 125 of which were in the Santee National Wildlife Refuge (Refuge). SCDNR treated 183 acres of cutgrass, bringing the 2016 total to 491 acres of treated cutgrass. In addition to spray treatments, the Refuge also stressed the cutgrass further by lowering water levels within impounded areas (Savannah Branch) right after the aerial spray for two-three months, and then followed up with a prescribed burn in February 2017. The areas were immediately re-flooded after the prescribed burn and kept high throughout the summer.  Those three treatments combined (spraying, altering hydrology, and prescribed burning), provided excellent waterfowl habitat restoration at the Refuge.

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Taken during the 2017 follow up survey, this photo shows that the cutgrass has been drastically thinned, allowing submersed and floating leaf plants to occupy the area, as well as allowing access into the area. Photo Credit: Casey Moorer

In 2017, Santee Cooper revisited the sites to assess any needs for treatment of regrowth. With the help of SCDNR’s wildlife management area maps, Santee Cooper repeated the mapping process. Santee Cooper treated 685 acres of cutgrass in 2017 (including the Refuge), while SCDNR treated 300 acres. In total, the two organizations treated 985 acres of cutgrass around Lake Moultrie and Lake Marion in 2017. Through the partnership between SCWA, Santee Cooper, SCDNR, and USFWS, a total of 1,476 acres of giant cutgrass has been treated over the past two years.

SanteeCooperCutgrass2016-2017We look forward to monitoring the success of the project this coming summer. It will take a couple of growing seasons to see the full impact of the project on fish and wildlife habitat, since it takes some time for the dense giant cutgrass stands to decompose. Once this occurs, these stands will open up to improve fish spawning habitat and to allow the growth of more beneficial waterfowl food plants. According to SCWA Executive Director, David Wielicki, “This project should result in the addition of over 1,000 acres of previously inaccessible areas for fisherman and waterfowl hunters to enjoy. It is also important to note that areas will require spraying every 4 to 5 years in order to keep the giant cutgrass from coming back.”

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