Ice-In and Ice-Out

One of the functions performed by the Branch Lake Association is to monitor the lake for ice-in and ice-out. This data is sent to the Lake Stewards of Maine to record in their database. 


Ice coverage for the winter induces changes in oxygenation and vegetation growth as well as the water temperature changes. For a more complete description of the value of this data, see the Lake Stewards of Maine and to track ice-out dates across the state for recreational purposes see the Maine Bureau of Parks and Land

The online databases are incomplete. Although we have sent information almost yearly since 2009, no ice-in dates appear and only 4 ice-out dates. We are following up on this. This seems to be the same with the online reports of IPP surveys. But, while the important thing with an IPP survey is that it was completed, the important thing with ice-in and ice-out data is the trend over time.


Consistency of measurement is important to make the data more valuable. Until 2013 we did not have a consistent definition of ice-in and ice-out. If ice comes in on January 1st and then melts on January 14 to 27th what do you count? Who is going to watch that closely? What if we have a cold winter but a flowing spring near Teacher’s Island leaves a spot that never freezes over? Some may count that as not ice-in but others would based on a rule of 50%, 80% or 100% of the lake having ice. Definitions differ from from lake to lake for many valid reasons.  The geography and winter residents here at the time of ice-in and ice-out makes a difference as to what can be measured. A satellite picture or drone picture would probably be the best. But will we have a drone shot every year every day? Not anytime soon.


Short of a drone fleet, we have been using the following definition of ice-in and ice-out for Branch lake since 2013:

  • Ice-in is when there is sufficient ice so that a duck could walk from the state boat ramp in a straight line to Leather’s rock on the opposite shore without getting wet. 


  • Ice-out is when the duck can’t stay dry (although surface water on the ice does not count). 


We like to have people checking for us on both Philips Drive and Branch View Drive looking from their side preferably with binoculars. This has not always been possible but we have had it done from at least one side every year since 2013. 


The earliest date we have on record for ice-out has been 20 March in 2010 (definition used is unknown). The latest date on record is 23 April in 2019. Most dates fall between 12 and 15 April.

Ice on Branch lake jan 25 20019.jpg
mallard duck on frozen lake.jpg