Roughly 8,000 acres along the South San Francisco Bay are devoted to salt evaporation ponds. The salt ponds range from blue green to deep magenta, three microorganisms in particular, Synechococcus, Halobacteria, and Dunaliella, influence the color of salt ponds. Fremont, Alameda County, California, USA. © march. 10 2008 Marco van Middelkoop/Aerophoto-Schiphol