On Nov. 14, a letter to the editor was published that made a number of assertions about the chemical triclopyr, known by its trade name Renovate, which has been used to control Eurasian Milfoil in Cazenovia Lake. The misstatements of fact in that letter were so substantial and potentially damaging that a detailed response was deemed warranted. This letter will address, in order, those assertions.
Renovate’s use in lakes and other bodies of water has been approved by the federal government and independently by the New York State Department of Environmental Conservation (DEC). DEC reviews proposals to use Renovate and issues permits for projects in which the potential benefits are expected to outweigh any potential side effects.
Renovate is applied to Cazenovia Lake before milfoil emerges to the surface in the spring of the year. At the time of application, any impact on the oxygen level in the lake is insignificant and of short duration. The control of milfoil through the use of Renovate does not appear to significantly promote the growth of blue green algae. In fact, no blue green algae blooms were reported in Cazenovia Lake in 2017, even though the lake was treated with Renovate and many other nearby lakes reported these blooms.
In regard to the fish kill mentioned in the letter, when the kill occurred, many weeks after the Renovate treatment, there had been unseasonably warm water conditions. DEC responded to investigate the fish kill and sent fish to Cornell for analysis; the fish were killed by parasites, not Renovate. In addition, if the fish kill was directly related to low oxygen levels from the rapid die off of plants, all fish species would likely have been affected, rather than just largemouth bass (kill occurred in 2010).
Contrary to the letter’s assertion, New York State does not ban the use of Renovate in lakes used as municipal water sources. The DEC may not approve the use of Renovate in such a lake, but not because it is not permitted.
Renovate is toxic to Eurasian milfoil. The effectiveness of Renovate, as proven by its use in Cazenovia Lake, is nothing but impressive. Experience has shown that Renovate is highly effective in the year of application and continues to restrict growth in the year following application.
Milfoil can be controlled by harvesting. There are portions of Cazenovia Lake where harvesting is being used exclusively either because other forms of weed control are being tested or because of unique environmental sensitivity. On the issue of harvesting, some facts may prove helpful.
A typical harvester can cut approximately 1.5 to 2 acres per day, so it would take one machine at least 100 days, or 20 work weeks, to cut 200 acres. Keep in mind that milfoil regrows in about six weeks, so you would need four harvesting machines just to cut the same 200 acres in six weeks and then you would have to do it all again. Were such a harvesting program to be conducted with rented equipment the cost would be approximately $350,000 per year.
Dredging Cazenovia Lake is not an option. As many of you know from reading about the dredging at Onondaga Lake, this process is very expensive. In addition to all the other potentially negative effects of dredging is the fact that the dredged materials could be very difficult if not impossible to dispose of due to many logistic and environmental considerations.
The undersigned believe that until such time as new treatments are approved which are cost effective to be used on Cazenovia Lake, that Renovate should continue to be used to control Eurasian milfoil.
Cazenovia Lake Association
Thad Yorks, Professor and Program Director
Environmental Biology, Cazenovia College
Glenn P Sullivan, Certified Lake Manager
Solitude Lake Management
