Solar Sea Salt Ponds
As the water naturally evaporates, the brines become increasingly salty, and we circulate them through our salt pond system.
Salt Ponds
The San Francisco Bay area boasts one of only two coastal saltworks in the United States. (The other is near San Diego.) What makes this area ideal for salt making: is a combination of shallow topography, clay soils, and Mediterranean climate - just enough rain in the winter followed by a long dry season of steady breezes and summer sunshine.
Within Cargill’s 12,000 acre system, the intake pond is the beginning in a series of evaporation ponds (sometimes called concentrators or concentration ponds). This is where we pump bay water into our pond system.
San Francisco Bay water is only 71 percent as saline (salty) as sea water: it contains 2.5 percent sodium chloride, vs. the ocean's 3.5 percent. The intake pond, like all our salt ponds, is surrounded by low-lying levees, or walls of dirt that separate it from the Bay and other ponds.
Evaporation Ponds
Flying over the bay or driving over some of the area's bridges, you will notice that evaporation ponds have distinctive colors: beautiful green and red hues, colored by the microorganisms that thrive at varying salinity levels.
As the water naturally evaporates, the brines become increasingly salty, and we circulate them through our salt pond system so as they get saltier, they get closer to our crystallizer beds.
Salt Pond Colors
Salt ponds range from blue green to deep magenta – colored naturally by the microorganisms that thrive as salinity levels increase.
Three microorganisms in particular, Synechococcus, Halobacteria, and Dunaliella, influence the color of salt ponds.
In the low-salinity ponds, both color and microbiology match the blue green waters of San Francisco Bay. As the brines concentrate, several algae, including Dunaliella, impart a green cast to the brines. With increasing salinity, Dunaliella out-competes other microorganisms and hues vary from pale green to bright chartreuse.
About midway through the pond system, the increased salinity promotes huge populations of tiny brine shrimp, which clarify the brine and darken it. The saltiest brine, or pickle, appears deep red, because Halobacteria take over and the hypersaline brine triggers a red pigment to form in the Dunaliella’s protoplasm.
The palette of salt pond colors reflects an unusual micro-biota. Yet it is more than just a curiosity of nature. The algae and other microorganisms create the basis for a rich ecosystem, supporting more than a million shorebirds, waterfowl and other wildlife. At the same time, these tiny creatures regulate water quality -- which promotes development of a higher quality salt.