Chemical Combat: A Look at Herbicides on Lake Hopatcong

Those familiar weed harvesters have taken up efforts around the lake in the last month or so, but many lake residents opt for a less visible approach to weed management around their docks and beaches.
weed_harvest_2010_-_main“Aquatic herbicides are hands down the least expensive way to go on a per-acre rate,” Chris Hanlon of Aquatic Technologies told a group of Bright’s Cove residents at a weed-management seminar this spring. As a result, they’re a popular option, particularly among those who live in the shallowest parts of the lake, such as Landing, Crescent Cove, Byram Cove, and Woodport.
Because permits are required for all aquatic pesticide use in New Jersey, the data on how much treatment the lake receives is pretty specific: according to Lake Hopatcong Commission records, 21 permits for aquatic pesticides have been issued so far this year, treating 149 acres—roughly 5.6 percent of the lake’s total acreage.
“For Lake Hopatcong, the majority of permits issued are for lake or property owners’ associations, beach clubs, or a group of residents that ‘chip in’ to cover the costs,” Donna Macalle-Holly, administrator of the Lake Hopatcong Commission, said.
The commission itself straddles a fine line on the use of herbicides.  A document given to residents who inquire about herbicide use suggests that, although the commission recognizes the safeguards in place within the state’s permitting system, the best long-term strategy to combat weeds is by preventing nutrient influx into the lake, with weed harvest as a short-term corrective measure. “While the commission does not question the effectiveness of using aquatic herbicides as a short-term remedy, we also recognize that herbicides are, in fact, poisons that are toxic to beneficial aquatic plants as well as nuisance plants, not to mention some other species living in Lake Hopatcong,” the document says. “So, as a practical measure, we would prefer less usage of aquatic herbicides in the future as opposed to more.”
With regard to minimizing nutrient influx into the lake, it’s not just about using phosphorus-free, lake-friendly fertilizer at least 10 feet away from the lake, replacing septic systems with sewers, cleaning up pet waste, not feeding the geese (decreasing water fowl waste), properly pumping out boat sanitation devices, and avoiding washing cars or boats near the lake—all of which are important.  The use of herbicides actually contributes to the nutrient levels, too, because the plants that die go to the bottom and fuel future weed growth.weed_harvest_2010_-_main
That issue was less problematic when harvesting operations were in full force. “When our harvesting program was funded and fully operational, the commission staff worked closely with [aquatic herbicide application] firms to coordinate our efforts,” Macalle-Holly said. “The harvesters would go in and harvest as many areas that were scheduled to receive pesticide treatments first. With this approach, most of the plant biomass is removed by the harvesters, then the applicators would treat the area and there was less plant biomass that would die off and sink to the bottom.”

For that reason, among many others, Macalle-Holly and the rest of the Lake Hopatcong Commission are seeking a stable source of long-term funding.
Five firms have received aquatic pesticide permits for use on Lake Hopatcong: Agra Environmental (Dover; 973-989-0010973-989-0010), Allied Biological (Hackettstown; 908-850-0303908-850-0303), Aquatic Analysts (Middleville; 973-383-6264973-383-6264), Aquatic Technologies (Branchville; 973-773-9567973-773-9567), and Knollwood Environmenta (Andover; 973-398-3517973-398-3517). About half of the treatment on the lake is applied by Allied Biological.
The N.J. Department of Environmental Protection’s Pesticide Control Program (PCP) provides completed permit forms to the commission before issuing permits. (Information on the permitting process is available at this link: and the permit itself is available here:
herbicide_permits_2010There are some restrictions to the types of pesticides that can be used, and the commission itself is restricted from using state funds to treat the lake with herbicides—a barrier that was put in place when the commission was formed. Treating the lake on a broad scale would not be effective anyway, Macalle-Holly said. “Since Lake Hopatcong is 2,658 acres and there are areas of the lake—because of its depth—that do not have aquatic plants, there would never be a need to treat the entire lake.”
Macalle-Holly adds that, to the best of her knowledge, there are no aquatic pesticides that treat tape grass, a native plant species in Lake Hopatcong that she says has received “nuisance” status, but does not reach the nuisance level of the Eurasian watermilfoil, which can be treated by herbicides.
Tapegrass has leaves that are up to 2 meters in length and have a central stripe, and serve as a valuable plant for refuge for aquatic organisms and a source of food for wildlife. It also stabilizes the sediments and near-shore habitats. “If you boat around the lake and look closely along the shoreline in the Woodport section of the lake, you will see the ‘floaters,’ which are primarily tapegrass now.  We are definitely removing more tapegrass in this year’s [weed harvesting effort] than we have in years past.”
For all other weeds, including the dreaded Eurasian watermilfoil, residents are frequently skipping the mechanical treatment in favor of a chemical approach.
To read about other weed treatment options, check out these past stories on
Got Weeds?  You’ve Got Options, Residents Learn (May 26, 2010)
Green Scene: How to Be a Tree-Hugging Seaweed Killer (June 17, 2009)

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