This question was raised recently by a Section party who traveled to Bow Falls, crossing Bow Lake on their way, and it must be in everyone’s mind when thinking of crossing any of the many lakes we find en route to mountaineering destinations in Winter, for example Bow Lake, Peyto, Eagle, Sherbrooke, Hector, Minnewanka, Louise, and Emerald.
The body of water you plan to cross may be covered with ice, but is it thick enough to support you? According to the Lifesaving Society, clear blue ice needs to be at least four inches thick to support a walking person.
For our purposes: skiing or sometimes snowshoeing, three inches is generally fine, but stay on them, and don’t fall.
I discuss this subject in the Safety page of the website, under Resources, but here’s a brief summation:
1. There can be no formula for ice safeness, or even thickness: on-the-spot inspection and experimentation is the only reliable way to know its condition at any time.
2. There are two main broad characteristics of ice that determine its strength: thickness and type, as the strength of ice varies widely, depending on the kind of ice.
3. Our problem of assessment doesn’t end with knowing what thickness and kind of ice to watch for: we still need to know how thick and what kind the ice actually is where we want to cross.
4. Finally keep in mind that the ice strength varies along your crossing, and beware of factors that could make it weaker ahead; periodic actual measurement and direct observation along your route would be the most reliable way to assess the ice strength, but again, that’s almost never done: we usually rely on someone else to go across first in the Fall, then get very nervous about skiing through water lying on the surface in the Spring.
Read the whole article at Home Page/Resources/Safety.
Orvel, Director of Safety