Bacteria and other thermophiles(heat loving microorganisms) usually
form the ribbons of color like you see here. The green, brown,
and orange mats are cyanobacteria, which can live in waters as
hot as 167 F (73 C). At this temperature they are usually
yellow-green. They become orange, rust, or brown as the water
cools. In cooler water other thermophiles may appear that
will modify the colors even more. Color may also change due to
stress, such as the intense sunlight of mid summer.