So the crew put their land survey expertise to work. Then they surveyed a one-mile baseline from the shore of Warroad Harbor onto the frozen lake. Once they established that line, the crew used an auger to drill through the ice every 10 feet along that line, took water depth measurements, and recorded them. As odd as it sounds, winter is actually the best season to do such work. Surveyors can measure points on the ice, which is stable, and much better than bouncing around in a boat.
Measurement is more precise.
In some cases where we can't use global positioning, land controls offer more accurate recordings of water depth. But the weather causes problems of its own. During this survey, the temperature was five degrees below zero with a wind-chill of about 20 degrees below zero. The water temperature was 31 degrees. In these conditions, we all need to be extra careful.