The River Vélez alluvial and delta deposits constitute one of the most important detrital aquifers on the south bàsìh o f Spain, given that its development provides water for Urban comsuption and productive agriculture. The setting up of Vihuela reservoir in the higher basin has caused a decrease Of the aquifer recharge. In addition, the persistent drought and the increasing exploitation of aquifer resources have produced a fall in piezometric levels accompanied by groundwater quality deterioration. A rise on nitrate concentration and a progression o f saline intrusion are the main consequences o f this 1985-1994 evolution