A new study released by the Lake George Association (LGA) reports that the aquatic herbicide ProcellaCOR, commonly used to control Eurasian watermilfoil, can persist in lake sediments for more than a year—raising fresh concerns about its long-term ecological impacts.
ProcellaCOR has been applied widely across the Adirondack Park in recent years, promoted for its ability to selectively target invasive milfoil. However, the LGA’s research found that while the herbicide dissipates quickly from the water column, its active ingredients and breakdown products remained in lake-bed sediments for over a year—sometimes at concentrations exceeding U.S. Environmental Protection Agency (EPA) safety thresholds for sediment-dwelling organisms such as mussels and aquatic insects.
“These findings raise important questions about the long-term effects of ProcellaCOR use on lake ecosystems, particularly when reapplication occurs before the herbicide has fully degraded,” the report notes. Concerns have also been raised that repeated use could contribute to the development of herbicide-resistant milfoil strains.
While some Adirondack lakes have turned to chemical control methods, the Upper Saranac Foundation (USF) continues to demonstrate that non-chemical, diver hand-harvesting remains one of the most effective and environmentally responsible tools for invasive species management.
For more than two decades, USF’s Aquatic Invasive Species Dive Team has successfully contained and reduced Eurasian watermilfoil populations to a rare occurrence in Upper Saranac Lake—once one of the most heavily infested lakes in the Adirondacks—without the use of herbicides. Through a combination of early detection, strategic hand-harvesting, and science-based management, the Foundation has achieved and maintained extremely low plant densities, setting a national model for sustainable invasive species control.
“Hand-harvesting allows us to precisely remove plants while protecting native species and avoiding unintended ecological impacts,” said USF Executive Director Guy Middleton. “It’s a proven approach that prioritizes long-term health of the lake over short-term chemical fixes.”
As questions about ProcellaCOR’s persistence continue to surface, Upper Saranac Lake stands as evidence that careful, science-driven, manual management can restore and maintain a healthy lake ecosystem without chemical intervention.
The full LGA study, Persistence of Florpyrauxifen-benzyl (ProcellaCOR) and Its Degradates in Lake George Sediments, can be viewed here
