A Lake That Breathes Color
Peyto Lake's brilliant turquoise is not a trick of the light, but a direct result of geology in motion. The lake is fed by the Peyto Glacier, a part of the larger Wapta Icefield. As this river of ice grinds its way down the valley, it pulverizes the bedrock into a fine, silt-sized powder called rock flour. This material consists of minerals like quartz and feldspar, ground into particles typically between 2 and 65 microns in diameter. These particles are so small and light that they do not sink. Instead, they remain suspended in the water column, creating an opaque liquid often called "glacial milk".
The concentration of this suspended rock flour is highest in the peak summer months of July and August. Increased meltwater from the glacier carries a heavy load of sediment into the lake, making the color exceptionally bright. In spring, as the lake thaws, the water is a clearer, deeper blue, but as the melt intensifies, so does the turquoise hue. By autumn and winter, the glacial melt slows dramatically, and the lake eventually freezes over, hiding its famous color under a blanket of snow and ice.