QA-CAS-2: Does the term “body of water” in the casual relief rule include bodies of ice and snow?

No. “Casual water” as listed in the rules is water as it’s commonly understood, in its liquid form. The rules do not grant casual relief from snow, ice, or even steam should you encounter it. Note that the Director can announce that ice or snow are casual obstacles, in which case they may be moved if they are on or behind your lie.