system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is the water at Banff such a light blue?
gpt
It has glacial milk in it.  Glacial milk is a very fine silt produced by the action of glaciers slowly pulverizing stone into flour.  It's so small that the particles remain in a near colloidal suspension instead of settling out.

The glacial milk reflects light in such a way that it makes the water almost look like light blue paint.