So just what is a Thermal Spring?
A thermal spring is simply a point of ground water discharge whose water temperature exceeds the regional average air temperature. Traditionally, if the water is warmer than 5oC above the average annual temperature in an area, then it was called a thermal spring. In the Banff area, where the average annual temperature is -0.4oC, any ground water that comes to the surface and doesn’t freeze could then be called a thermal spring! A better definition used by some scientists is that a thermal spring is a point of ground water discharge whose temperatures exceeds the regional average air temperature by more than 10oC. Other definitions for cold (0-9oC), cool (10-19 oC), warm (20-29 oC), and hot (>30 oC) springs also are possible. Others divide them into warm (<37 oC) and hot (37 oC) springs, largely based on human body temperature.
If we use the latter definition, only the Upper Hot is truly a “hot spring” with Kidney Spring on the cusp of hot and warm and all the rest merely “warm”.