Using a selective herbicide is an excellent way of selectively removing Eurasian watermilfoil while allowing native plants to flourish.
— Washington State Dept of Ecology

We have been working closely with the state and also studying what other lakes have been doing successfully. The newer, more selective and specific herbicides do not kill most aquatic plants. The Washington State Department of Ecology reports, “Using a selective herbicide is an excellent way of selectively removing Eurasian watermilfoil while allowing native plants to flourish.” As a result of this research, we will be applying to the state for a permit to use milfoil-specific herbicides on a very limited basis to address some particularly difficult patches. The goal is to treat these areas so they are reduced sufficiently to be able to use our traditional methods once again for ongoing control. The permitting process is long and complicated, but with cooperation from the state and the licensed herbicide applicator, we are hoping that we will get this permit in a timely manner.

Frequently Asked Questions

Q: What is the name of the herbicide we intend to employ?
A: Renovate 3 (liquid) and Renovate OTF (granular) formulations of triclopyr herbicide.

Q: When would treatments occur?
A: Treatment would not be applied until there is enough active milfoil growth to maximize herbicide uptake (Plants should be filling two‐thirds to three‐quarters of the water column).  Treatments will likely be scheduled between late May and late June, and optional late summer (post Labor Day) spot‐treatments may be considered in some cases.

Q: How does treatment occur?
The concentrated liquid formulation will be injected subsurface through weighted hoses using a boat‐mounted pumping system.  The solid (granular) formulation will be evenly applied using a spreader.

Q: Will the herbicide be applied to the entire lake?
Treatments would occur within the areas shown on these maps (Lake Dunmore | Fern Lake), but the amount of acreage treated is not expected to exceed more than 100 acres (approximately 10% of the lake’s total surface area) during any single year, and the actual amount treated each may be significantly less. 

Q: Is it safe to swim when the herbicide is being applied?
A: Swimming in the lake should be avoided until testing shows that the concentration has been reduced to allowable levels--usually 24-48 hours after application.

Q: Are there impacts to the lake's native plants?
Significant adverse impacts to the native plant community are not expected from the proposed Renovate herbicide treatments to Lake Dunmore.

For more information, please read the LDFLA's application to the Vermont Department of Environmental Conservation.