# Confined Aquifer

Confined Aquifer: In the hydrogeology branch of geology, a confined aquifer is an aquifer that is overlain (and underlain) by a layer of low permeability, such as clay, shale, or silty clay. In fact, the two confining layers contain the storage and flow of groundwater, such that the aquifer maintains hydraulic pressure (or head). Unlike an unconfined aquifer, confined aquifers do not have a water table. However, the depth to groundwater in a groundwater monitoring well that is screened within a confined aquifer, will typically demonstrate a potentiometric surface elevation that is higher than the aquifer confining layer itself.