MONTPELIER >> The state toxicologist says Vermont needs better scientific studies supporting continued use of a chemical to combat the sea lamprey that have been killing salmon, walleye and other species prized by anglers in Lake Champlain.

Meanwhile, it's unclear whether the U.S. Fish and Wildlife Service will be allowed this fall to treat three rivers feeding the lake with the chemical known as TFM, which fishing enthusiasts see as key to maintaining the health of sport fishing stocks.

Sarah Vose, a toxicologist with the Vermont Department of Health, said in an interview that the state's basis for approving use of TFM was a non-peer-reviewed study dating from 1973. She said she and other officials are working to set goals and methods for a study or studies that would be based on sounder science.

Vose said the Health Department has been looking at TFM against the backdrop of heightened concern about chemicals in drinking water. Lead in the drinking water of Flint, Michigan, and, closer to home, an industrial chemical known as PFOA in drinking water supplies in southwestern Vermont and nearby New York state have highlighted those concerns recently.

The Health Department advises the Agency of Natural Resources, which makes the final decision on whether to issue the lamprey control permits. The Health Department recently lowered its limit for TFM in drinking water from 35 to three parts per billion, while it awaits the new studies.


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"We're not stopping the (lamprey control) program or slowing the program," Vose said. "The discussion was about moving forward while making sure the drinking water is free of chemical contamination."

But on Friday, a day after Vermont, New York and federal officials met to discuss the matter, Vermont Fish and Wildlife Commissioner Louis Porter said it was still unresolved whether this year's plan for using TFM would go forward. Porter's department is part of the Agency of Natural Resources.

The chemical is normally applied to rivers feeding the lake every four years. Three Vermont rivers had been scheduled to be treated this year: the Missisquoi, Stone Bridge Brook and the LaPlatte. The LaPlatte flows into Lake Champlain's Shelburne Bay near where the 70,000-customer Champlain Water District has its intake.

George Desch, deputy commissioner of Vermont's Department of Environmental Conservation, said when there was a plan to use the TFM in the Winooski River, which flows into the lake between Burlington and Colchester, the Burlington water district installed a new filter system on its intake in the lake. But he said for the Champlain district to do something similar before this fall's scheduled treatment of the LaPlatte would be "ambitious."

James Ehlers, executive director of Lake Champlain International, a nonprofit that operates a major annual fishing derby and is involved in several environmental issues on the lake, has been objecting strongly to the idea that the lamprey treatments might be blocked. He said the state would do better to turn its attention to sewage overflows that occur on rivers feeding the lake in heavy rains.

But Vose called ensuring public water supplies are free of chemical contamination the top priority.

As for whether the U.S. Fish and Wildlife Service, the entity seeking a permit to use the chemical, will be able to do so this year, Desch expressed doubts.

"I would call it a yellow light. But they have to show me why I wouldn't turn the light red," Desch said.

A call to Bradley Young, lamprey control program coordinator with the federal agency's Vermont office, was not immediately returned.