Evaporation ponds are used in salinity management mainly to extract salts from the water system in a watershed. The objective of an evaporation pond is to collect saline water, usually drainage water, and reduce the volume of water through evaporation. The salts remain inn the evaporation pond. The design of the ponds need to consider the long-term monthly and annual potential evapotranspiration of the region, and balance the expected volume of saline water inflow with the expected evaporation rates, thus resulting in a required surface area for the ponds.
Evaporation ponds can be designed on farm level, or on regional level. Due to regulations related to toxic elements (selenium), a large number of small evaporation ponds have the preference on the west side of the San Joaquin Valley in California.
When evaporation ponds have only solid salts left, the salts can be scraped and collected. Several studies have been conducted to investigate the commercial opportunities of the collected salt, but most conclude that the purity of the salts is too low to compete with commercial salt production.