ProcellaCOR: Why We’re Concerned

February 13, 2023

The Lake George Association and Lake George Waterkeeper – along with the towns of Hague, Dresden and Ticonderoga, the Adirondack Council, and more than 4,600 concerned citizens – have grave concerns about a pending permit application by the Lake George Park Commission (LGPC) to use a chemical herbicide in the Lake for the first time ever.

We believe the proposal to use the herbicide ProcellaCOR to treat the invasive species Eurasian watermilfoil is lacking the scientific evidence needed to ensure the herbicide will not have adverse impacts on the specially protected waters and ecology of Lake George. We have called upon the Park Commission, to no avail, to pause its pursuit of ProcellaCOR permits until the questions about potential impacts have been answered.

The following are our concerns regarding statements made by the Park Commission in support of its permit application. If you share our concerns, click here to let Gov. Hochul, the Park Commission, NYSDEC and the Adirondack Park Agency know.


LGPC Says: ProcellaCOR has been approved for use on invasive aquatic vegetation by the United States Environmental Protection Agency and NYSDEC.

Our Concern: Just because ProcellaCOR has been given general approval as an aquatic plant treatment doesn’t mean it’s the right treatment for Lake George.

First, the manufacturer’s label clearly states the herbicide is for use in “slow-moving/quiescent waters with little or no continuous outflow.” Lake George is far from “slow-moving” or “quiescent.” Its circulation patterns are dynamic and complex, and computer modeling shows that ProcellaCOR will drift out of the treatment area within hours, possibly into deeper waters where it will take far longer to break down and will increase the potential for adverse impacts to critically important plants and organisms that are native to Lake George.

Lake George is not just any other Lake. It holds New York State’s highest water quality designation (Class AA Special), has its own state agency specially designated to protect it (unlike any other water body in the state), is a drinking water source for local people and visitors, and serves as a major economic engine for the southern Adirondack Region, drawing visitors from around the world due to its renowned water quality. It is a Lake deserving of special precautions, not risky experiments.


LGPC Says: There are “no risks” to human health nor any restrictions on drinking water usage or contact recreation such as swimming after herbicide use.

Our Concern: The notice received by property owners in the area of the proposed test sites states that “a restriction on all water uses in the treatment zone during the application will be in effect” for approximately three hours per site. In addition, “Following application, livestock watering and irrigation will be restricted” for approximately 10 days the ProcellaCOR label also warns against water use by shoreline property owners for irrigation of residential landscape plants and homeowners’ gardens, and states, “Do not compost any plant material from treated area.”


LGPC Says: ProcellaCOR is effective at killing invasive plants “without impact to native plant and animal populations.”

Our Concern: Plant studies conducted at Minerva Lake following the use of ProcellaCOR found adverse impacts to Nitella, a native plant that is critically important to Lake George because of its ability to sequester phosphorus and minimize algae growth. In addition, according to a presentation made by Adirondack Park Agency staff, ProcellaCOR has adverse impacts on alternate flowered watermilfoil, a native and protected species in Lake George, as well as the native coontail plant. The United States Environmental Protection Agency has also found ProcellaCOR to be “slightly toxic” to invertebrates.

Following a comprehensive review of pre-existing research on the impacts of ProcellaCOR on non-target species and organisms, nationally respected limnologist and Lake George macrophyte expert Carol Collins, Ph.D., found that there is a significant probability of “highly significant adverse impacts” to non-target and protected species and organisms.


LGPC Says: ProcellaCOR “breaks down naturally and quickly, within 3-4 days.”

Our Concern: According to the manufacturer’s Safety Data Sheet, ProcellaCOR may break down quickly through photodegradation in 8-18 days in shallow waters where light permeates. But in deeper waters, such as some portions of the planned treatment area and adjacent areas of 35 feet or deeper, the breakdown via hydrolysis will take 111 days.


LGPC Says: ProcellaCOR is needed in Sheep Meadow Bay and Blairs Bay due to the “persistent growth of milfoil” and the ineffectiveness of other harvesting methods.

Our Concern: There has been no milfoil management attempted in Sheep Meadow Bay for eight years or Blairs Bay for five years. The current methods of hand harvesting and diver-assisted suction harvesting are minimally invasive and have proven effective.


LGPC Says: The two proposed treatment sites have “dense beds” of milfoil, necessitating the need for chemical intervention.

Our Concern: The ProcellaCOR label warns that, “Water bodies containing very high plant density should be treated in sections to prevent the potential suffocation of fish.” The proposed plans for these bays calls for each to have one expansive treatment taking only 30 minutes to complete.


LGPC Says: The herbicide will be released to the Lake “at depths of 8-10 feet” to achieve the desired concentration.

Our Concern: SOLitude, the herbicide firm selected by the Park Commission, stated they typically apply ProcellaCOR at a depth of 2 feet below the surface, but the Lake George application would be at 5-6 feet.


The fact is there are simply too many unanswered questions about the potential impacts of a chemical herbicide on the unique and special waters of Lake George to run head-long into an experimental treatment. Any testing of ProcellaCOR on the water, plants and organisms of Lake George should be conducted in a laboratory, not in the Lake itself. The Lake George community works diligently to keep potentially harmful substances out of the Lake; we simply can’t justify turning around and putting something potentially harmful in.

The LGA and Lake George Waterkeeper continue to urge the Lake George Park Commission to hold off on its plans for chemical use until the proper scientific analyses can be conducted and the public can have confidence that such a plan will not harm the Lake we all love.