700 wells were located. Large supplies of groundwater are available (over 15 000 kl/day) with very small drawdowns from the unconfined aquifer, which consists of Quaternary sediments overlying Gambier Limestone to a depth of 100-110 metres. Salinity varies from 300 - 1 800 mg/l with higher salinity in the swampy areas. Water levels vary from 2 metres on the plains to 20 metres in the dune to the east. A confined aquifer (Dilwyn Formation) which is separated from the unconfined aquifer by a confining bed of clays and lignites, underlies the area but is not used. The groundwater is used for irrigation, stock and domestic supplies. Groundwater pollution occurs near the Coonawarra vine growing area.