Lake Champlain ice cover seen from Red Rocks Park on May 17, 2022. DEC photos.

Vermont Business Magazine As Vermonters patiently wait for spring temperatures, the Department of Environmental Conservation (DEC) invites the public to report when Vermont’s lakes and ponds lose their ice cover. Also known as the “ice-out date,” this date marks when lakes or ponds become ice-free from shore to shore.

“Tracking ice-out dates helps our scientists to not only decide when to begin seasonal water quality sampling efforts but also better understand how climate change impacts our lakes and ponds,” said DEC Commissioner Misty Sinsigalli. “With long-term records of lake ice, our scientists can monitor climate trends across Vermont and the region.”

When ice covers lakes, the water below separates into layers based on temperature and density. When the surface ice fully melts in the spring, the heavy cold water sinks, and the water column fully mixes. Water samples collected at this time of mixing show the baseline amount of phosphorus a lake will have available to fuel algae and aquatic plant growth during the spring and summer.

“Since 1977, we have collected information on the spring water quality of lakes larger than 10 acres in size,” says Mark Mitchell, a limnologist with DEC and Lake Champlain Sea Grant. “Over those nearly fifty years, we have seen trends of earlier lake ice-out dates across Vermont and New England, which can be a sign of climate change.”

You can report lake ice observations using the DEC’s Lake Ice Reporting form.

Many lake communities around the state also hold ice-out contests, usually in the form of a raffle where the winners can receive prizes or cash. Some of the more famous and long-running ice-out contest sites include Joe’s Pond in Danville, Lake Iroquois in Hinesburg, and Lake Memphremagog. These contests are an engaging way for lake associations and communities to encourage folks to observe lakes and ponds throughout the year.

To find spring water quality information, view the Vermont Lake Score Card. For more information, visit the DEC Lakes and Ponds Program.

DEC scientist collecting water samples on Molly’s Falls Reservoir in Marshfield shortly after lake ice-out in early spring.

The Department of Environmental Conservation is responsible for protecting Vermont’s natural resources and safeguarding human health for the benefit of this and future generations. Visit dec.vermont.gov and follow the Department of Environmental Conservation on Facebook and Instagram. 

Vermont Agency of Natural Resources Website.