File:2009-10 31 BOS-SFO 401z.jpg

English: These are salt evaporation ponds on the shores of San Francisco Bay, filled with slowly evaporating salt water impounded within levees in former tidelands. There are many of these ponds surrounding the South Bay. A series microscopic life forms of different kinds and colors predominate to in series as the water evaporates. First comes green algae. Next brine shrimp predominate, turning the pond orange. Next, dunaliella salina, a micro-algae containing high amounts of beta-carotene (itself with high commercial value), predominates, turning the water red. Other organisms can also change the hue of each pond. The full range of colors include red, green, orange and yellow, brown and blue. Finally, when the water is evaporated, the white of salt alone remains. This is harvested with machines, and the process repeats.