The Vermont Department of Environmental Conservation (DEC) is asking Vermonters to report when lakes and ponds lose their ice cover, also known as the “ice-out date.”
Once a lake or pond is completely free of ice from shore to shore, DEC scientists can begin their spring water quality sampling efforts. The ice-out data also helps scientists track the effects of climate change in Vermont.
“We need the public's help to alert us to ice-out information to better time our data collection,” Oliver Pierson, Lakes and Ponds Management and Protection program manager, said in a news release. “The more data we have from around the state on the timing of ice-out, the better we can track water quality changes and impacts from climate change on our lakes.”
DEC scientists have been collecting spring water quality information since 1977. When lakes are covered in ice, the water underneath is layered, or “stratified,” into sections based on water temperature, with the coldest water temperatures near the surface.
Soon after the ice cover is gone in the spring, the water layers weaken and mix. When the water mixes, scientists collect water samples to see the total amount of phosphorus a lake will have available during the growing season for phytoplankton, algae, and aquatic plants.
“We try to sample lakes within 7 to 10 days of ice-out, because that's the best time to collect information about the average conditions in the lake at the start of the growing season,” said Leslie Matthews, environmental scientist with DEC. “Tracking ice-out dates over time can also be important because in some lakes, earlier ice-out may lead to more phosphorus release from sediments during the summer, which can help fuel algae blooms and growth of aquatic nuisance vegetation.”
The Department of Environmental Conservation has an online ice-out reporting form that the public can use to share their observations. For more information, visit the department's “Lakes and Ponds” page at dec.vermont.gov/watershed/lakes-ponds.