Year of 2017

Salt evaporation ponds in San Francisco Bay, California

Along the southern shores of San Francisco Bay, acres of shallow water are isolated from the rest of the bay. The water in these ponds evaporates and the salt is harvested and processed for sale across the western United States. The evaporation ponds show different colors because of the microorganisms that thrive in the high-salinity water. Only some salt-tolerant algae live in the ponds with the highest salt concentration.

Salt evaporation ponds, also called salterns, salt works or salt pans, are shallow artificial ponds designed to extract salts from sea water or other brines. The seawater or brine is fed into large ponds and water is drawn out through natural evaporation which allows the salt to be subsequently harvested. The ponds also provide a productive resting and feeding ground for many species of waterbirds, which may include endangered species. The ponds are commonly separated by levees.