Checking your lake's water temperature is a very basic management tool but critical to many actions. Fertilization starts once the water is 60 degrees in the spring and ends in the fall once the water temperatures drops below 60 degrees. Trout are stocked once the water gets below 70 degrees and they will need to be harvested once the water gets above 70 degrees. When fish are stocked the temperatures must be within five degrees or the fish have to be tempered. Stocking fish in contrasting water temperatures could be disastrous.
This thermometer is armored so it can take hits unlike your classic aquarium thermometer. These are the same thermometers AES uses.