State agencies are investigating whether a pesticide sprayed for mosquito control caused a fish kill in an Addison County lake earlier this month.
The fish die-off was seen in Fern Lake a few days after trucks applied a chemical in the area to kill adult mosquitoes.
Leicester resident Zachary Saxe has lived near Fern Lake for a decade. He often fishes and swims there, and the first weekend in June his swim was interrupted by the sight and smell of dozens of dead fish. Saxe, who once worked as a wildlife technician, went out to collect samples in plastic bags.
“I have a small row boat; we cruised the shoreline. And it was every species in the lake: bluegill, pumpkinseed, perch, crappie, bullhead, largemouth bass, smallmouth bass, rock bass. And in all different sizes,” he said.
The area near Fern Lake is notoriously buggy. It’s part of the Brandon, Leicester, Salisbury, Goshen Mosquito Control District, a public entity that sprays pesticides to control both larvae and adult mosquitoes.
A Fish and Wildlife biologist first blamed the Fern Lake fish kill on spawning stress and rising water temperatures.
But a subsequent report by state aquatic biologist Rick Levey said that the die off “may be related” to the mosquito spraying. Levey noted that the active ingredient in the pesticide is malathion, which is extremely toxic to fish and other aquatic life. His report said malathion was sprayed within 100 feet of the water days before the dead fish were reported by Zachary Saxe.
“At this point, it’s still an unknown for everybody. There are folks looking at what possible exposure levels could be in the water from an application,” said Cary Giguere, who oversees the pesticide program at the Agency of Agriculture.
Giguere said the fact all eight species in the lake died is a red flag for scientists at the Department of Environmental Conservation, or DEC, since it could indicate something other than natural causes killed the fish.
“And that does raise concern for some of the folks that we’ve been talking to at the Vermont DEC,” he said. “We plan on working with the DEC and the BLS District in the future to sort of get some surface water samples from Fern Lake that correlate to a spray event from the district.”
Gary Meffe chairs the board of the mosquito control district. He said the district has a 20 year history of spraying in the area with no problems reported.
“We’re quite confident that nothing has changed at this point and that the cause of the fish kill is most likely as the state biologist reported: high temperatures during spawning in a very shallow end of the lake that caused a number of species to die,” he said.
Public records and state emails show that biologists at two separate state departments – fish and wildlife and environmental conservation – disagree on the possible cause.
Zachary Saxe, the Fern Lake resident, still has the dead fish he collected stored in his freezer, but officials say the samples are likely too decayed to detect pesticides.
Saxe doesn’t want the district to spray insecticide on his property. The district now allows people to be placed on a no-spray list. But Saxe said it should be the other way around with property owners requesting the spraying instead of being told to opt out.
“And whether or not the fish in my freezer were killed by the pesticide or not, it made me look into this, and really my blood just started to boil,” he said. “I couldn’t believe there were spraying this stuff all over the landscape down here.”
Meffe said the district – out of an abundance of caution – has stopped spraying temporarily near lakes. Meanwhile, officials at the Department of Environmental Conservation say they’re conducting an enforcement investigation to determine if all conditions of the district’s general pesticide permit were followed.
Matthew Probasco is the pesticide general permit coordinator at the DEC. He said one question is whether the mosquito control district notified designated state officials – including himself and the Agriculture Agency’s Cary Giguere – within 24 hours of an adverse incident, such as a fish kill.
“We have no record of them reporting that within 24 hours,” Probasco said.
But District Chairman Meffe said the state Fish and Wildlife Department was notified.