This year, for the first time, the LaPlatte River is slated to be treated with the pesticide TFM, to reduce populations of larval sea lampreys in the LaPlatte before they reach Lake Champlain.
US Fish and Wildlife Service Sea Lamprey Control Program Manager Bradley Young explains that adult sea lamprey live in the lake, but spawn in tributary rivers and streams, where young live for four years. Adults wound other fish, particularly game fish.
“The reason for the (TFM) program overall is that the number of lamprey in Lake Champlain have a very significant impact on a number of fish species, including lake trout, landlocked salmon, but also endangered sturgeon, that we’re trying to restore,” says Vermont Fish and Wildlife Commissioner Louis Porter. And the LaPlatte “is one of the biggest rivers in Vermont right now for lamprey population,” says Young.
Enter the US Fish and Wildlife Service’s application to use TFM in the LaPlatte River.
The TFM application has raised concerns about the pesticide’s potential health impacts, especially since the Lake Champlain Water District public water intake is located nearby in Shelburne Bay. And there has been recent discussion about how much TFM in the water is safe. It started, notes Vermont State Toxicologist Sarah Vose, when the Vermont Department of Health reviewed a 1973 study about TFM’s effects and consulted the Environmental Protection Agency (EPA) about the study, which had established a 35-parts-per-billion state action level for TFM.
Vose notes, “The 1973 study was of very poor quality and it’s not sufficient to base a health advisory level on.” The EPA declined to include the study in their toxicology database, which, says Vose, “definitely made us question the validity of the study.”
With no toxicity level established, the Health Department workers are left lacking information they’d normally use to determine a safe drinking water level for TFM. “We really don’t know what the long-term health effects are. We don’t know if it’s going to stick around in your body for a long time,” Vose notes. “Those studies just haven’t been done, so we can’t evaluate the studies to recommend the advisory level.”
In this situation, says Vose, the Health Department uses the reporting level, which is the minimum amount of TFM detectable in the water using laboratory testing – so as soon as there is enough TFM in the water to show up on a lab test, it’s hit the allowable limit. This new limit is three parts per billion (down from 35 parts per billion based on the 1973 study).
Young notes that a study modeling currents, wind, and other factors indicated that at worst, 1.8 parts per billion of TFM might reach the Shelburne Bay water intake. However, an additional water cleaning method will be used out of caution.
“Because of concerns regarding the potential impacts to the Champlain Water District’s (CWD) drinking water intakes, we are working with the CWD, their consultant, and others to insure that the CWD facility has the capacity to treat the water to remove TFM,” notes Department of Environmental Conservation (DEC) Deputy Commissioner George Desch. “The modeling predicts that this will not be an issue for CWD, however, the consequences are deemed too significant for the service area, should the modeling be wrong, so the contingency is to provide a treatment system for the worst case scenario.” CWD General Manager Jim Fay describes a system of adding powdered activated carbon to the water at the treatment plant; this removes TFM from the water before it reaches the public as drinking water.
“The activated carbon will work to neutralize any TFM that may possibly make it to our intake site in Shelburne Bay, but that intake is a half mile off from shore in 75 feet of water, so it’s a very low risk that it may hit anywhere near our intake,” Fay says. “But with the new standard with the Health Department, we wanted a much higher margin of error and safety for our customers, hence the treatment.” The water is tested both as intake and as finish water, Fay notes.
The activated charcoal system, a portable unit, will be installed, tested, and used for a few weeks: “Pretty much immediately when the application to the river begins, and we’re going to keep it on for a few weeks until we’re sure everything has passed through the environment and there’s no risk to the public,” Fay says.
Desch says, “The treatment system proposed for CWD – addition of powdered activated carbon (PAC) – has been demonstrated to effectively remove TFM from the drinking water to below detection.”
Young points out that TFM has been used elsewhere in Lake Champlain for over two decades, without problems. The Winooski River is one place where TFM is used. The treatment facility has the charcoal system in place.
“We’re not experimenting on (people). It’s not like this is the first time we’ve tried this. We’ve been doing it for 25 years in Lake Champlain, and there’s never been a problem anywhere,” notes Young. “It’s been a very successful, very safe process.”
So why worry about TFM at all?
“We simply don’t know what the health effects of TFM are in people,” says Vose. “There haven’t been a lot of studies done in mammals, so we do not want to provide any false assurances to the public that there is no risk when we really don’t know what the risk is.”
There are still potential challenges that could arise to prevent the treatment from going forward, Porter notes. “We have a plan and an expectation that that plan will come together. We have enough confidence in that plan and our expectations that it’ll come together that we’ve talked about it publicly, because people want to be kept up to date on where we are on the project.” However, if for example issues with the activated carbon treatment arise, the project might not be completed in the fall timeframe when weather will still allow the work to occur.
A public presentation about lampricide treatment in the LaPlatte River is scheduled for Monday, Sept. 26, 7-9pm in Shelburne Town Offices Meeting Room One. TFM treatment of the LaPlatte River is slated for this fall. A follow-up story in the Sept. 29 Shelburne News will provide more information about the ecological background of this issue.