Even the largest expenses do not guarantee success.
Dozens of lakes in New Hampshire are already infected with invasive aquatic plants, and experts increasingly acknowledge that if an alien species has managed to establish itself in a water body, it is practically impossible to completely eradicate it. As reported by the New Hampshire Bulletin, the fight against these invaders requires hundreds of hours of volunteer work and tens of thousands of dollars, but most often only slows the spread of the plants. Ecologists warn that the problem has long exceeded the boundaries of a single state and is becoming part of a broader environmental crisis in the U.S.
Every summer on Lake Sunapee in New Hampshire, volunteers go out on the water almost daily. Some survey the water area by boat, others search for new infection hotspots from kayaks and paddleboards, while divers manually remove dangerous plants from the bottom.
The main adversary is variable milfoil, one of the most aggressive invasive species that have spread in American water bodies.
"We are not making progress. We are just keeping it under control," acknowledged volunteer Lee Petruk in an interview with the publication, who has been involved in the fight to preserve the lake for many years.
According to the New Hampshire Department of Environmental Services, invasive aquatic plants have been officially detected in about 100 lakes and water bodies in the state. However, specialists from the environmental organization NH LAKES believe that the actual number of infected water bodies may be significantly higher.
The problem lies in the biology of the plants themselves. Many of them can regenerate even from a small fragment of a stem. Sometimes, a tiny piece of a plant that gets on a boat, trailer, or fishing gear is enough to transfer it to another water body.
Climate change gives invasive species an additional advantage. Warmer waters and increased nutrient concentrations create conditions in which alien plants begin to outcompete native species.
"If left unchecked, they will become dominant," warned David Niles, head of the New Hampshire Department of Environmental Services.
According to experts, the consequences affect not only ecology. Overgrown thickets degrade water quality, displace native plants and animals, and make many lakes unsuitable for swimming, fishing, and recreation.
"When lakes are filled with invasive plants, recreation becomes impossible," noted Elizabeth Harper, executive director of the Lake Sunapee Protective Association.
For many American regions, this also means direct economic losses. Lakes remain an important element of the tourism industry and affect property values around water bodies.
The fight is expensive. Removing plants by divers can cost hundreds of dollars per outing, while using herbicides or special underwater suction systems can run into tens of thousands of dollars per treatment. Just in early June, New Hampshire authorities approved grants of nearly $235,000 for local organizations working to curb the spread of invasive species.
However, even large expenditures do not guarantee success. Ecologists emphasize that the only real chance to completely eliminate an invasive plant arises when it is detected at the very early stage.
This happened on Lake Sunapee, where in 2024 an inspector noticed just one stem of the dangerous plant caught on a boat. After that, a large-scale operation was organized to survey the lake and remove all detected plants. A year later, new inspections found no signs of infection.
However, such stories remain more of an exception. On the neighboring Baptist Pond, the problem was noticed only a few years later, but that was enough for the complete eradication of the plant to become practically impossible.
According to experts, this is why many American lakes today are in a state of endless defense. When an invasive species has already established itself in the ecosystem, the task changes: it is no longer about victory, but about constant and costly containment.
"The question is not whether eradication is possible. The question is how much money you are willing to spend on it," stated Brea Arvidson, director of programs at NH LAKES.
