Announcements / Opportunities / Science

Tracking the Thaw

Lake Willoughby, just after ice-out in 2009.  (Photo credit: Kellie Merrell, VT DEC)

Lake Willoughby, just after ice-out in 2009. (Photo credit: Kellie Merrell, VT DEC)

Can you believe that just two years ago we were witnessing some of the earliest ice-out dates in recent history? By mid-March the ice had gone out on many lakes and ponds in the Champlain Valley and southern Vermont, and by late March and early April, in the Northeast Kingdom. Despite the fact that the meteorological term polar vortex has become standard vocabulary for many of us over the winter, spring is officially here and it’s time to start thinking about recording and sending us your ice-out dates.

While the Lakes and Ponds Management and Protection Program defines ice-out as the date when all the ice cover has completely thawed in a waterbody, there are varying interpretations. As long as the criteria for determining the ice-out date are consistent from year to year, long-term records are considered credible and can be used to track trends in annual ice-out events.

We’re not offering a cash prize for submitting your date like the well-known, lucrative contest for guessing the ice-out date on Joe’s Pond in Danville. However, we are offering an even better reward: the chance to contribute to our understanding of climate change in Vermont.

Since the timing of ice-out depends primarily on average air temperatures over several days or weeks, ice-out dates are considered to be climate indicators. Using ice-out records, researchers at the Watershed Management Division and the Air Quality and Climate Division are hoping to better understand and predict trends in statewide climate conditions.

Although not as commonly tracked, ice-in, or the earliest date in which a lake freezes over and stays frozen for the remainder of the season, may be an even more important indicator of climate.

To join this citizen science effort, please send your 2014 ice-out dates, as well as ice-in dates if tracked, to Bethany Sargent at And if you haven’t yet submitted records of ice-out or ice-in dates for any years prior, please send those as well. Lastly, if you are sending dates, be sure to include your contact information as well as a brief explanation of your interpretation of ice-out.