Hard Water

By: Richard D. Gainar, CEBS – Lake Management Committee

As cold temperatures slow the metabolisms of all living creatures, winter lakes such as Roaming Rock Lake exhibit reduced rates of photosynthesis and respiration. In temperate lakes covered by ice, water temperatures are about 4˚C (39˚F) top to bottom except at the very top where ice forms between 0˚C (32˚F) and 4˚C.  The unique properties of water molecules make ice less dense than water, so it floats on the top of the lake, allowing fish and other life to remain alive below.

Ice can become so thick that little light penetrates to the water below. Photosynthesis, already slowed by the cold temperatures, ceases to take place altogether in the dark water limiting weed and algae growth.  The ice also separates the lake water from the atmosphere so that no direct diffusion of oxygen can occur.  Although fish and other organisms need very little oxygen when water temperatures are so cold, oxygen may entirely deplete, resulting in a winter fish kill in some lakes.  Our fish population’s health is helped by significant water flow from our many tributaries.  The oxygen-enriched water flows under the ice all winter.

As always, Love the Lake and Be Lake Responsible.