Share 'Why do water bodies suddenly change colour'

Recently there was a sensational news in my part of the world. It seems suddenly the waters of a part of the river Krishna near Nagarjunsagar Dam turned green ( the river waters here will usually be light blue in summer and muddy in rainy seasons) . Image Credit: Google And several theories started doing the rounds. But why do water bodies suddenly change the colours? It is mostly because of the…