Will Our Lakes Freeze Over Completely?

By Carmelo “Mel” Russo

When the temperature gets this cold for several weeks, there is always talk of Seneca and/or Cayuga Lake freezing over completely. Old timers talk of car races on the ice of the lakes from Geneva to Watkins, and from Seneca Falls to Ithaca. Yet, it is very rare for this to happen in these modern times. The rarity of a total Lake freeze-over is due to the interaction of four physical factors associated with the lakes: their great depths, their extensive surface area, the frequent Finger Lakes winds, and industrial heat discharge.

In the fall, when surface water temperatures start to cool, the surface waters get heavier and they sink. This factor coupled with vigorous wind action, causes a mixing of the waters until there is nearly a uniform temperature from the surface to bottom of the lake. Eventually this temperature of the lakes will become 39.2 degrees Fahrenheit. When water gets colder than this, it becomes lighter and remains near the surface. The water may eventually reach its least density of 32 degrees. At this temperature water becomes ice/slush and this material is light and floats, thereby allowing lakes to freeze from the top down.

In wintertime on Seneca and Cayuga Lakes, the wind normally mixes the cooler surface waters with the warmer deeper waters resulting in heat transfer to the upper layers of water. Therefore, the lakes rarely freeze over completely, except where it is constantly shallow. In addition, power plants, and now chilling plants, as well as other industries are constantly removing the cool, 39.2 degree water and discharging much warmer water at the surface. This warm water discharge adds significant heat to the lakes and inevitably maintains a certain area of unnatural, open water. I’m afraid that the “old timer” reports of the lakes freezing over are gone forever. However, if we get a short period of calm, together with extremely cold temperatures we sometimes experience, you may be able to tell of the legendary year when the lake froze over all the way!

PS: Freezing and thawing are very healthy for a body of what, especially like those of Seneca and Cayuga Lakes with a huge supersaturated reserve oxygen supply. Thawing in late winter/early spring allows the lakes to warm up eighty times more slowly, for awhile, due to the heat of fusion of water. This slows the growth of algae thereby helping to maintain the geological youth and water quality of a lake.