Why do rivers sometimes get milky or turquoise colors from glacier meltwater?
Quick Answer
Glacier meltwater often carries fine rock flour, which scatters light and gives the water a pale blue, turquoise, or milky color. The color comes from tiny suspended particles, not from chemicals dissolved in the water.
The Full Story
As glaciers grind over bedrock, they produce extremely fine sediment called rock flour. Meltwater streams carry this suspended material into rivers and lakes. The particles are so small that they scatter shorter wavelengths of light, making the water appear bright blue-green or milky gray. This is common in glacial rivers in places like the Alps, the Canadian Rockies, and New Zealand. The effect is most noticeable in sunny weather and where the water is deep enough to absorb other wavelengths.
Key Facts
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