The Natural History of Foster City, California
by James K. Sayre
a draft manuscript
12 May 2005
Chapter 26: Salt Production in the South Bay
An early economic use of the San Francisco Bay and its surrounding marshlands was the production of salt by solar evaporation ponds. Salt has been commercially produced from the waters of the San Francisco Bay since 1862 [Ver Planck]. The waters and baylands of the south bay are the most ideal location in California for the production of salt by the process of solar evaporation of sea water.
In the early days of salt production, there was intense competition between various small producer of salt in the Mt. Eden area along with other producers in the Fremont, San Jose and Palo Alto to San Mateo shore areas. Originally all machinery used to pump the waters was driven by windmills. A few relics of these can still be seen standing after one has crossed the San Mateo Bridge going east and then looks to the south (right) after hitting dry land on the Mt. Eden side of the bay.
Salt production using solar energy is basically a process of fractional crystallization. The first precipitate is calcium carbonate or gypsum. After the salt has precipitated out of the solution, the remaining liquid, called bittern, is sold to chemical companies who can use the bittern as raw material for further production of chemicals. This evaporation or drying process takes five years. The annual harvest of salt is scraped of the dry beds of the salt ponds from September to the end of the year.
The economics of the salt production business gradually led to a consolidation of the companies involved. This process occurred mostly in the period from 1900 to 1940. Now Leslie Salt is the sole operator of salt ponds in the south bay. .i.Leslie Salt Company; was acquired by Cargill, Inc. of Minneapolis, Minnesota in 1978.
The salt ponds do provide good feeding, resting and wintering habitat for many species of water birds. Algae can grow in the concentrated salt water. Also, small fish, such as mudsuckers, sculpin and topsmelt can live in the mildly concentrated salt waters [Gilliam].
When the water is more salty, shrimp can live. All this animal life is tasty fare for visiting water birds.
End.
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