ASHFIELD — The Selectboard plans to decide on and fund a solution to remove invasive species from Ashfield Lake in fiscal year 2026.

Fanwort, also known as cabomba caroliniana, is an invasive species native to the southern United States, as well as Central and South America. Fanwort in Massachusetts was first observed in the 1890s, according to the United States Geological Survey (USGS), and was added to the state’s Prohibited Plant List on Jan. 1, 2006. Fanwort can travel to different bodies of water through various means such as water flow, boats and birds.

The plant typically grows in water that is less than 10 feet deep, according to the state Department of Conservation and Recreation. The highly competitive plant negatively impacts ecosystems by outgrowing native vegetation and limiting room for fish and recreational use, according to Water and Wetland co-founder, Joe Onorato. Water and Wetland is a lake, pond and wetland management company based in South Grafton.

The invasive species has been on the Selectboard’s radar for more than a year, but the board has had trouble finding funding for a solution. Ashfield volunteer hydrologist Drew Haerer has been monitoring the fanwort and offering solutions to address it.

The two main options Haerer brought to the Selectboard include purchasing a mechanical harvester to manually remove the fanwort or using an annual herbicide treatment to manage the fanwort. According to Town Administrator Paul McLatchy III, both options are costly and have their ups and downs.

“With the herbicide treatment, there is a lot of public sentiment against using herbicides of any kind in the lake, which is understandable. With mechanical harvesting, it is much less invasive. There are no chemicals or anything, but the town would have to purchase some kind of harvester and then you would have to man it, for someone to go around and literally pull these invasive species out. Either way it is difficult.”

The mechanical harvester would cost approximately $80,000 and someone would need to operate the machine to extract the fanwort. One herbicide treatment costs $45,000 and would need to be applied multiple times every few years as needed. Neither solution will completely eradicate the fanwort. The Selectboard showed interest in the mechanical harvester as it would be a one-time purchase.

“It is going to take multiple years to treat this anyway and even after that it’ll still require smaller treatments throughout the year, so it’s never going to go away fully,” McLatchy said. “It’s always going to have to be maintained versus a one-time treatment.”

During a meeting with the Selectboard last week, Haerer said that before making any decisions on treatment, the town should conduct a study of the lake. He recommended using available funds to survey the lake’s invasive species this fall and then return for discussions on treatment.

“It’s tough because there’s no great option,” Haerer said.

Haerer said surveyors would likely only recommend the chemical treatment method. However, Selectboard members are skeptical that Town Meeting voters would approve of herbicide use.

“I just don’t see the town approving the use of fluorine in the lake,” Selectboard Chair Steven Gougeon said, “regardless of what the science says about it.”

Last week’s discussions ended at a standstill, with no solid solution identified. Ultimately, Selectboard members and Haerer agreed to continue researching mechanical harvesters and to look into conducting a thorough study of Ashfield Lake.

Staff writer Madison Schofield contributed reporting.