<p>Bay water (which is effectively sea water due to tidal action) is let into a pond which is then closed off and the water is left to evaporate in the sun. When that pond reaches a certain level of concentration, it is drained into the next pond where is is further concentrated, and so on until it reaches a final pond where it is left to dry out completely.
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There it is scraped up by a bulldozer (as seen mid-right) into a big pile ready to be loaded onto train wagons for transport by rail to the land of icy roads... The long line of box-cars can be seen on the rail lines just above the top pond.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/40648743@N00">Jitze Couperus</a> from Los Altos Hills, California, USA
CC BY 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/jitze1942/6814276518/">Salt Ponds in Newark (South-East side of San Francisco Bay)</a>