Lake Tillery residents hear state’s plans to control hydrilla

At a recent meeting hosted by Center Rural Fire Department in Norwood, Lake Tillery and other local residents received information from state officials regarding a hydrilla problem.

Hydrilla is an invasive aquatic weed native to southeast Asia and the Pacific Islands, and is now the most widespread aquatic weed in the United States, officials said. It does not need a lot of light to grow, which it can do at a rate of 262 linear feet in 35 days.

What makes hydrilla tough, according to North Carolina State University professor Dr. Rob Richardson, is the turions, compressed buds which can stay in the ground and sprout up to seven years later.

Richardson said it is important to know what desirable plants should be maintained while removing weeds like hydrilla.

When it comes to controlling hydrilla, Richardson said, “there are always physical and environmental constraints to every site that limit what we can do, and there are economic limitations to what we can afford to do.”

Richardson said management of hydrilla has to “interfere with the biology of the plant.”

“We have to both prevent growth, but also prevent reproduction,” he said.

He there it can take up to 10 years of management “where you may not see any hydrilla.”

Hydrilla was first round in Lake Tillery in 2006 at the Swift Island Boat Ramp just off N.C. Highway 24-27 in Montgomery County, according to Drew Gay of the Aquatic Weed Control Program (AWCP) of the North Carolina Wildlife Resources Department (WRC).

Gay said it was the first time hydrilla had been found in the Yadkin Pee Dee River Basin, and herbicide was used for the next three years until the use of grass carp started in 2009.

Of the 130 acres of hydrilla found in the lake, Gay said most was in the southern end.

An advisory group consisting of members of the AWCP, the WRC, N.C State University and Duke Energy made recommendations for how to treat the problem.

Herbicide called fluridone will target the two biggest areas of hydrilla, around the Swift Island and Norwood boat ramps, over a 90-day period starting in late spring.

Beginning in April, 3,688 triploid grass carp will be released over a two-month period, which officials consider “the keystone component of lake-wide management of hydrilla.”

According to a graph presented to citizens at the meeting, hydrilla in the lake increased to 150 acres in 2009, but was close to zero between 2019 and 2021. However, the acreage of hydrilla has spiked to 250 acres in the last two years.

Erin Molloy, an environmental scientist with Duke Energy’s aquatic management program, said Duke “is a local stakeholder that provides funds for these aquatic plant management activities.”

During a question and answer session, Rob Emens said the boat access areas were the two areas to be treated this year.

“If you don’t live right next to one of those ramps, then your area has not been slotted for treatment this year,” said Emens, who manages the aquatic weed program for NCDEQ.

Emens said the decision to treat the boat ramps came from the advisory committee, adding it was “a financial decision.”

“To try and treat every bit of hydrilla in the lake, your cost would spin out of control,” Emens said.

Gay said the plan is to have 20 carp per acre this year instead of 15 because of the increase in acres of hydrilla.

Emens said lawn fertilizer which runs off lawns into the lake can feed hydrilla as well as produce an algae bloom.

“You should not be applying fertilizer near the edge of the water. Typically, we want to see a 50 to 100 foot setback for applications of fertilizer and pesticides,” Emens said.

When asked by one resident about not being able to keep his boat docked, Emens said there would be fragments of hydrilla all over the lake.

“So what we don’t want you to do is take those fragments to another lake,” Emens said. “I would advise you to contact a herbicide application service and get a quote from them to see what it would cost to treat your area.”