These can be fractured or potentially fractured rocks which do not have a high primary permeability, or other formations of variable permeability. Aquifer extent may be limited and water quality variable.
Minor aquifers generally yield moderate quantities of groundwater with a variable quality. However, in places high yields can be obtained of good quality groundwater. Good examples of these aquifers include those associated with the Bokkeveld Group and weathered and fractured rocks of the Karoo Sequence.
Minor aquifer systems are important both for local supplies, and for supplying baseflow to rivers.