Confined aquifer: An aquifer bounded above and below by impermeable layers, where water is stored under pressure. Unconfined aquifer: An aquifer with its upper boundary open to the atmosphere ...

The aquifer is shallow and unconfined or partially confined and generally not suited for supplying drinking water. It is mainly used for agriculture and fish culture.

The confined aquifer (artesian) is by far the largest and, unlike the unconfined that was filled to capacity in the mid-1980s and mid-1990s, has not been full since about the early '50s.

This aquifer is deeper than 100 meters (330 ft.) and considered confined because it is protected by impermeable layers of soil that do not allow superficial water above to move through it.