Why do quarries often have blue water?

Some water bodies exhibit blue hues due to the presence of suspended rock flour. This is seen in carbonate (eg. limestone) aggregate quarries where quarry activities produce a large volume of dust from the crushed rock. read more

Presence of micro-organisms tends to turn water greenish. So clear aqua water generally usually has low microbe and clay contents. An exception is milky aqua, low microbe water in glacial lakes and glacier fed rivers which has appreciable suspended rock-flour. These latter water bodies can have striking aquamarine to turquoise hues. read more

There are generally significant suspended fine solids (rock flour like loess) in quarry water. This would appear milky white in a small amount of water, but in a deep quarry, like those in many images, the effect is to amplify the naturally blue appearance of the water in sunlight. read more