Salt ponds date back at least a couple of centuries as a way to manufacture salt for food, road de-icing and other purposes. The process for mining salt with ponds is actually relatively simple. It involves collecting seawater or brine in evaporation ponds, which are shallow ponds with high surface area designed to help speed evaporation. Most often, these ponds are placed close to natural sources of seawater so that the water doesn’t need to be transported prior to evaporation. Modern salt ponds typically make use of reinforced liners to prevent leaks and avoid the loss of valuable product. This has the added benefit of improving the quality of salt produced since it isn’t contaminated with soil or other substances.
Salt manufacturers will typically have multiple ponds, sometimes dozens of them spanning hundreds of acres. When ponds are close together, they are separated by levees. Water is allowed to flow into these ponds so that the evaporation process can begin. Evaporation reduces the water level until the brine reaches about 25% salinity. This is when the salt begins to crystallize so that it is ready to be harvested. Come harvest time, trucks with rakes will go through and scoop salt from the pond. This salt is then rinsed and prepared for resale. The entire process can take up to five years.
