Springs are upwellings that bring brine to the surface level in a natural and continuous way, which allows its use without need for drilling or pumping. There are a number of them in the Salt Valley and its surroundings, but only four of them (Santa Engracia, La Hontana, El Pico and Fuentearriba) are usable, because its flow is permanent (about 3 liters per second) and salinity is near saturation point (210 grams per liter).