P-J photo by Eric Zavinski

Herbicide treatment of Chautauqua Lake involving five municipalities in May was found to be successful, according to an independent third-party study released this month.

The study was funded in partnership between the county and the Chautauqua Lake and Watershed Management Alliance in support of the Chautauqua Lake Weed Management Consensus Strategy Memorandum of Agreement (MOA).

Herbicide treatment was designed to reduce curly-leaf pondweed and Eurasian watermilfoil with little to no impacts to the lake. The treatment took place May 15 through May 17 in the towns of Ellery, Ellicott and North Harmony and within the villages of Celoron and Lakewood.

The study was done by Princeton Hydro, LLC and included pre- and post-treatment macrophyte surveys, water quality testing and discrete laboratory testing for herbicides in selected treatment, drift and control zones.

The herbicide application of Navigate (2,4-D) and Aquathol K (dipotassium salts of endothall) was conducted by Solitude Lake Management under regulatory permits and oversight by New York State Department of Environmental Conservation.

“Between pre- and post-treatment conditions, curly-leaf pondweed displayed a statistically significant decrease in the treatment areas while Eurasian watermilfoil also displayed a decrease but this was not statistically significant,” the third-party study indicated. “In contrast, four of the more common native species all increased from pre- to post-treatment conditions. The only exception to this was a decrease in elodea in the drift zone but note this was not statistically significant.”

“Overall, the treatment was successful at its intent, and data pertaining to this project showed adverse impacts to be minimal.”

The objectives of the study were:

• evaluate potential risk to local drinking water supplies through water quality testing;

• provide third-party verification of applicator-collected water samples and applicator-contracted laboratories;

• provide a third-party assessment of potential herbicide drift into non-target locations and potential impacts to non-target species

• evaluate the apparent efficacy of herbicide treatments;

• and evaluate apparent effects of herbicide treatments on ambient water quality.