Stained Glass Salt Ponds, San Francisco

When flying over San Francisco Bay, be sure not to miss the gorgeous and picturesque local color salt evaporation ponds operated by the US company, Cargill. It’s one of the world’s most amazing man-made wonders. The colored salt pond looks like a palette. It’s a shallow artificial pool for evaporation of sea water or other salt water to get the salt inside.

First, sea water or other saline is injected into the salt ponds, the water disappeared after natural evaporation and then the salt shows up.

It usually takes 5 years changing sea water into brine which has to be transferred to another pond to from the salt after.

The color of salt ponds varies a lot from blue-green to dark red purple depending on the salinity and microorganisms in which are able to thrive in this environment.

There are three kinds of microorganisms impacting the color of salt ponds which are Synechococcus, salt bacilli and Dunaliella.

Salt ponds operated by Cargill look exactly like abstract paintings.

The pond with low salinity is bluish-green and becomes green after the increase of salt content and the growth of several algae like Dunaliella.

With further increase in salinity which helps Dunaliella defeating other microorganisms, the color of the pond will change from light green to yellowish green.

The microorganism in salt ponds having the algae and other micro-organisms, basis of species-rich ecosystems which could feed more than 1 million kinds of shorebirds, waterfowl and other wildlife, is spectacular and also capable of adjusting the water to allow us getting higher quality salt.

The increase of salinity stimulates the tiny brine Artemia breeding which are able to purify salt water and dim the color of the pond.

Highest salinity of the salt pond is dark red contributed by salt bacilli and Dunaliella within which the protoplasm forms red pigment.