These salt evaporation ponds are situated in San Francisco Bay. They are shallow man-made ponds designed to produce salts from sea water or other brines. The color indicates the salinity of the ponds. In low to mid-salinity ponds, green algae are predominant. In middle to high salinity ponds, red algae are. Millions of tiny brine shrimp create an orange cast in mid-salinity ponds. Other bacteria that also contribute different tints.