How they do it — hint: carp — is a sight. But it’s curbing hydrilla on Lake Wylie.

Folks usually roll up to Lake Wylie hoping to pull fish out of it. These aren’t just any old folks. And they aren’t just any old fish.

Lake Wylie again is getting a load of sterile grass carp. Literal weed-eaters, stocked to rid the lake of invasive plant species. Again, a truck will pull up to a cove and slide the carp down a giant tube by the hundreds. It’s become a familiar sight of spring on the lake, and it’s why hydrilla isn’t.

“We think the hydrilla is under control,” said Joe Stowe, executive director of the Lake Wylie Marine Commission.

Stowe’s group already is working toward Riversweep in October, their growing high school life jacket competition program and other issues impacting Lake Wylie. Hydrilla isn’t at the top of the list. It wasn’t too long ago, the invasive weed ranked high among the biggest threats to the lake.

In 2008 there was concern hydrilla would take root in the lake and not let go. Hydrilla and Alligatorweed, a similar invasive species, were spotted at about a dozen spots on Lake Wylie, including four large patches, mainly on either side of the Belmont peninsula in North Carolina. It stretched into coves and onto the main channel.

Hydrilla can grow up to a foot a day and make lakes inaccessible for boating and swimming. It can threaten public water intakes, power generation and irrigation.

The marine commission, Duke Energy and wildlife agencies from both Carolinas partnered in 2008 to stock the first 500 sterile Asian grass carp. They only use sterile carp to keep from inadvertently introducing another invasive species. But sterile carp mean more are needed annually to control hydrilla, which can lay dormant as tubers in the mud for a decade, as the fish die.

Too many fish risks harming other animals as they’d eat all the available vegetation. Too few risks a return of the “scourge,” as one former marine commissioner often referred to hydrilla.

According to a South Carolina Department of Natural Resources aquatic plant management plan, Lake Wylie needs 576 grass carp this spring. Down from a high of 1,800 fish in 2009, and in line with annual restocking efforts since. Wylie is one of 64 water bodies statewide on the management plan that has a public comment period open through March 30.

Local, state and federal sources will provide more than $2 million toward invasive plant control this year on South Carolina waters. The South Carolina program accounts for more than 160,000 acres of invasive aquatic plants controlled since it began in 1981.

The only other York County waterway getting help is Crawford Lake in Kings Mountain State Park in York County. Lancaster Reservoir, Sunrise Lake and Lake Wateree make the list from Lancaster County.

Less than 100 of Lake Wylie’s 13,443 surface acres have hydrilla growth. All are in North Carolina. Herbicides are recommended along with carp. Duke will continue to monitor effectiveness. The state plan recommends carp stocking each spring for at least three more years. All fish are at least a foot long.

Residents can help, too. Experts say plants and animals never should be dumped from aquariums — that’s the best guess for how hydrilla took hold — where they can get into public waters. Boaters should make sure they aren’t transporting plants from one water body to another on their vessels.

For more information or to comment on the state plan, visit dnr.sc.gov/invasiveweeds. Comments can be emailed to invasiveweeds@dnr.sc.gov.

This story was originally published March 16, 2017 at 3:05 PM with the headline "How they do it — hint: carp — is a sight. But it’s curbing hydrilla on Lake Wylie.."