Follow-up to my last two postings... Diablo Lake behind the 389 foot tall Diablo Dam on the Skagit River in the Cascade Mountains in Washington State. .................................................. Glacial flour or rock flour, consists of fine-grained, silt-sized particles of rock, generated by mechanical grinding of bedrock by glacial erosion. Because the material is very small, it becomes suspended in river water making the water appear cloudy, which is sometimes known as glacial milk. When the sediments enter a river, it turns the river's color gray, light brown, iridescent blue-green, or milky white. If the river flows into a glacial lake, the lake may appear TURQUOISE in color as a result:) Bill P.S. Zoom worthy.