The San Francisco Bay Area boasts one of only two sea salt works in the entire United States. It is an ideal area for salt making, thanks to clay soils and a Mediterranean climate - just enough rain in the fall, winter and spring, followed by dry summers with steady breezes and plenty of summer sunshine.
First stop on the tour of our 12,000-acre operating system is the intake pond -- the beginning in a series of evaporation ponds (sometimes called evaporators, 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.) Once inside our system, bay water begins its transformation into brine. Over five years, the brines will evaporate, concentrate and travel several miles before eventually yielding pure salt crystals.
The intake pond, like all salt ponds, is surrounded by levees, or walls of dirt that separate it from the Bay and other ponds. These levees, which trace original shoreline and early property lines, have shaped our baylands for more than 100 years. Most were built in the late 1800s to reclaim marshland for agriculture and then salt-making. Today, they're maintained by our wooden dredge, the Mallard II.
Mallard II has plied San Francisco Bay's salt ponds since her keel was laid in 1936. The crew of Mallard II works year-round, maintaining about 10 miles of the 80 mile levee system each year. The one notable exception: when Mallard II heeded the nation's call during World War II, retrieving artillery shells from the Bay floor around Mare Island and Port Chicago.
Anchored on her spuds, or stabilizing legs, the dredge scoops up mud from a borrow ditch to place atop the levee. She's remarkably fuel efficient - the Mallard II can operate for two months before refueling.
Mallard II is typically accompanied by a flock of birds that flutter and circle overhead, eager for the tasty fish and other food brought up with each bucketful of mud.
Mallard II helps maintain a network of gates, pumps and siphons to move water from the salt concentrator ponds to the evaporation ponds.
Roughly 8,000 acres along the South San Francisco Bay are devoted to salt evaporation ponds – and all of this land is protected by the Don Edwards San Francisco Bay National Wildlife Refuge. Evaporation ponds (and the marshes that surround them) provide important habitat for more than 70 species of birds, including several endangered species. Because the ponds are shallow - an average of 1.5 feet deep - it's easy for shorebirds and waterfowl to find a meal in the low- and mid-salinity 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. Learn more about the unique salt pond colors.
As the sun and wind evaporate water from the brines, they get saltier. The saltiest brines are moved to crystallizers within our industrial plant sites.