If you've ever flown into or out of the San Francisco airport, you have probably looked out the window and wondered about those weird red ponds scattered along the edge of the Bay. Wonder no more: they're sea salt harvesting ponds!
I was recently invited along on Diamond Crystal Salt's annual sea salt harvest right here in the San Francisco Bay. Let me tell you, it was a fascinating trip from Bay to box. Oh, and why the startling red color in those ponds? You'll never guess.
Sea salt harvesting is actually a long tradition here in the Bay Area. A combination of the shallow shoreline, the long sunny days, steady temperatures, and the coastal winds create an ideal environment for harvesting sea salt. Originally, there were several individually-owned salt operations all along the coast, starting with Captain John Johnson in 1854. These were eventually bought and consolidated into one operation by Leslie Salt Company, which in turn was bought by Cargill's Diamond Crystal Salt in 1978.
If you buy a box of Diamond Crystal Sea Salt, you are getting 100% San Francisco Bay sea salt. This is Cargill's only sea salt operation in the world, and in fact, the only solar sea salt production facility in the United States, period. (Their popular Diamond Crystal Kosher Salt comes from subterranean salt water deposits.)
The process for harvesting sea salt on this commercial level is really a scaled-up version of how sea salt has been harvested for centuries. They create a series of interlocking shallow ponds that are exposed to the sun and wind. As the water evaporates and the salt concentrates, the water is moved along the chain of ponds closer to the actual harvesting facility.
The sea water starts off with a natural salinity of about 3% and ends up at about 25% salinity. At this point, the salt starts to crystallize and can be harvested. Get this: the whole process takes about five years!
Once it's ready for harvesting, a truck with a rake attachment breaks up the salt bed. A harvester comes along to scoop up the salt and transfers it to dump trucks, which then carry the salt to the washing facility. The salt is rinsed first in a brine solution to wash out calcium and other impurities, and then in actual Bay water to dissolve the magnesium chloride. What you're left with is 99.8% pure sodium chloride sea salt.
The finished sea salt is transferred to huge outdoor mounds. Over time, a crust forms on the outside of the mounds, protecting the pure sea salt inside. As the salt is needed to meet market demand, another bulldozer pushes it onto conveyor belts that take the salt inside the facility for final processing, kilning, and packaging. From there, to the stores and to your kitchen.
A lot of work has been done between Cargill and the US Fish and Wildlife Service to restore and maintain the wetlands along the Bay shore. Cargill has reduced its salt harvesting facility to about 3,000 acres, turning nearly 40,000 acres over to the Wildlife Service. The Don Edwards National Wildlife Refuge supports seven endangered species and serves as a way-station for migratory birds. They are about 8 years into a 50-year plan to fully restore the marshlands in this area.
As to the red color in those ponds you see flying over San Francisco Bay, it comes from algae and brine shrimp attracted to the higher salinity of the salt ponds. These organisms don't survive once the salt water reaches its highest salinity levels, no worries about shellfish in your sea salt.
On the whole, I was really impressed with the low-fi nature of this whole sea salt production. Until the salt is actually harvested and transferred to the final processing facility, the process is remarkably un-mechanized. The sea water is evaporated naturally by the sun and wind. The water is also transferred from pond to pond almost entirely by the force of gravity and the tides, with only a few mechanical pumps at key locations. As far as I could determine, nothing is added to the water to make the process faster or change the nature of the sea salt. The fact that at the time of harvesting, the salt is already nearly a pure product is pretty amazing.
Take a look through the slide show above for the full tour and check out the sea salt harvest for yourself!
• Diamond Crystal Salt
• Don Edwards San Francisco Bay Wildlife Refuge
Related: Washington Cherries: From Orchard to Pie
(Information for this post was gathered during a press trip sponsored by Cargill Diamond Crystal Salt. All views and opinions expressed in this post are the personal views of the author.)
(Images: Emma Christensen)
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Facinating! Thanks for this piece.
Speaking of salt, traditionally the 8th year wedding anniversary is Salt (and Bronze). Any fun salt gift ideas?
you're right... I've always wondered what was! so nice to finally know, and that it's salt, not chemicals. thanks for the post.
christina
I'm sorry, but this came off sounding like a commercial for Cargill, sort of like the frequent promotions for Ikea. This industrial process is incredibly harmful to the ecosystem, and "restoration" is a euphamism for digging a ditch and filling it with water to replace ecosystems that spent thousands of years evolving. 3,000 acres is a huge amount of land considering how much oceanfront property has been destroyed in our lifetime. We buy artesinal salt from the Meadow, that is collected by hand or much smaller scale equipment.
Even more charming: Cargill slave labor in Africa
http://www.laborrights.org/stop-child-labor/news/11077
My folks live on Great Exuma in the Bahamas, where there's a salt pond. On a trip to visit a few years ago, the weather wasn't great, and it was extremely windy. This made for perfect salt harvesting conditions, and we headed over to the salt pond after eating some grouper at a great little road-side fish fry.
I want to respond to @Emmi as our team collectively had quite a bit of discussion internally on whether to do this tour. We are of course aware that Cargill is a huge corporation (like most of the companies that bring our food to the table) and they have mixed reviews on many fronts (again, like most of the companies in the imperfect food system).
We decided that we had the opportunity to document the process of how a vast amount of salt in the United States makes its way to the table, and ultimately we judged this to be of interest and value to readers. We are not evaluating Cargill's entire industrial record; that is not the topic here. If we tried to evaluate the entire record for every company we feature (including many "small" "local" ones!) I think that many if not most would fail some standard of fairness, ecology, wages, etc. etc. We attempt to report as fairly as we can on specific pieces and processes - which here includes the perspective of the US Fish & Wildlife Service.
Overall, our perspective is that it is important to share information on even the most industrial of food processes, considering that the vast majority of people in this country source their food from such processes. We love featuring artisanal, small batch producers as well - and we have a lot of content on these! - but we feel that it would be unnecessarily limiting (and really not of service) to focus only on small producers.
If, after reading this post, you decide to put a lot more effort into choosing where your salt comes from, then great! That's certainly one way this post can be of service.
If you have other feedback on this post, please email us directly at kitchn@apartmenttherapy.com. Thanks for your feedback!
Thanks for that information, Faith. I did enjoy reading this and obviously I adore Kitchn and Renest on AT (I link to you guys all-the-time on my blog). However that is exactly why I am a bit disappointed when I see Ikea constantly pop up on Renest blog, and my main point is that at some point, while towing the corporate line, it sounds like a plug for the company. I read this blog specifically because it does seem conscientious. The post is fine, I'd just prefer to see a bit more balanced information, like how the 3,000 acres of salt mining could affect an estuary instead of hearing Cargill brag about restoration.
Thanks for this. Post and discussion both fascinating!
this was pretty awesome to read. thanks for posting!
I've lived in the SF Bay Area for several years and seen the salt mounds, pretty cool to find out about the process that gets it there
loved this post! thanks for sharing!! re-posted immediately after reading :P
http://twopeasteenypod.blogspot.com/2011/10/sea-salt.html
Interesting indeed, but I still remain skeptical about Cargill.
I recall reading about the FWS buying the salt ponds from Cargill for around $130M; while Cargill stated it would help the gov't clean up the high concentrations of mercury, which are a result of more than a century of salt production. Its nice to see them take a little responsibility for their actions. Furthermore, they and another developer were looking to build between 10,000 and 12,000 homes on this property and I'd be willing to bet that their dedication to maintain and improve habitat quality is in direct response to the governments rejection of their initial housing plan.
Massive manufacturing operations are fascinating for sure, but there is a mass amount of ecological destruction that results from the process.
it's a shame that they remove the magnesium chloride. Not only is it one of the most naturally bio-available dietary sources of magnesium (great for you) but it also provides subtle taste enhancements (think electroconductivity) to food which cannot be mimicked by sodium chloride alone. The main problem is that it tends to pull water out of the air and get "oily" looking. I can't believe that you can only find seasalt with magnesium only at a much higher price. (and highly worth it)