All issues related to the arrival of the COVID-19 virus aside, it has been a strange winter in Vermont. The last 90 days have given us weather that is both warmer and wetter than normal. With these changing weather patterns, we are now seeing the first signs of spring, including the melting of lake ice.
The DEC’s Lakes and Ponds Management and Protection Program is seeking help from the public in tracking lake “ice out”. Ideally, we’d like to know the date when all ice has disappeared from a lake or pond, however any observations you make regarding our thawing lakes would be greatly appreciated.
Submit your lake ice observations here: https://dec.vermont.gov/content/vermont-dec-lake-ice-out-reporting-form
Tracking the dates that our lakes thaw helps Vermonters understand how our waterbodies respond to a changing climate. Some lake communities are quite competitive about tracking ice out dates (down to the minute!), and for the rest of us, it’s just a pleasant indicator that summer paddling and swimming are on their way.
For our water quality monitoring staff, ice out is used to understand biogeochemical processes occurring in our lakes and ponds. “Spring Phosphorus” sampling has been conducted by the DEC’s Lakes and Ponds Management and Protection Program on waterbodies at least 10 acres in size since the 1970’s.
Not long after the top layer of ice melts, lake water begins to warm. The warming surface water begins to sink, and, fueled by spring winds, combines with the denser water at the lake bottom. Eventually, the once stratified lake churns evenly from top to bottom. This is referred to as “lake turnover”, and it occurs in both spring and fall. Phosphorus (the “P” in “Spring P”) readings taken during spring lake turnover are indicative of the amount of phosphorus available for fueling plant and phytoplankton growth in the coming season. Lake turnover generally occurs 7-10 days after ice leaves the lake completely. Therefore, knowing when the ice leaves the lake gives our monitoring staff the ability to plan for water quality sampling.