COVINGTON -- The hydrilla that has been a thorn in the side of fishermen at Lake Varner will soon be snack food for hungry grass carp.
The fish will be set loose in the lake around the first of May in hopes that they will get rid of the hydrilla, a fast-growing, invasive aquatic plant that can be found in about 75 percent of the 820-acre lake, which also serves as the county's drinking water reservoir.
The hydrilla was first discovered about seven years ago, and since then, it's affected everything from the water treatment process to fishing to the bird population.
The most ecologically friendly method, and the best chance to thoroughly cleanse the lake, appears to be stocking it with sterile grass carp.
"Carps think hydrilla is like cake and ice cream. They are voracious eaters and they will control this," said Jason Nord, water production manager at Cornish Creek Water Treatment Plant.
County commissioners recently approved a bid of $57,500 from Cline Service Corporation for a fish barrier that will be installed in Lake Varner to prevent the carp from going downstream into state waters, where they might decimate harmless vegetation.
"It will be an ongoing process for several years to eradicate this stuff," Nord previously told the Citizen in a 2010 interview, noting that stocking 3,000 to 5,000 carps would need to take place annually for five to seven years.
"We don't expect it to go anywhere without the fish getting in there and helping us control it," Nord said.
Sunlight perpetuates hydrilla's growth, and given that Lake Varner is rather pristine, the sunlight can penetrate deep into the lake, creating fertile breeding ground for the plant.
The hydrilla has been getting tangled in the lines of fishermen and clogging the intake pipes that pump water from the lake into the treatment facility. It's also caused the death of numerous birds at the lake, including bald eagles, ospreys, Canada geese and coots.
They're the victims of Avian Vacuolar Myelinopathy, a neurological disease primarily affecting bald eagles and American coots in the Southeastern United States, and there is evidence the source is the hydrilla, or rather, cyanobacteria that grows on top of the leaves of the hydrilla. The cyanobacteria, also known as blue-green algae, contains a neurotoxin that is deadly to birds. Birds affected by AVM after eating it have been found to have brain and spinal cord lesions. They lose muscle coordination and have difficulty flying and swimming.