The fertile Barossa Valley comprises about 72 square miles in portions of the Hundreds of Moorooroo, Belvidere, Nuriootpa and Barossa in the North Para Catchment Area and includes the centres of Nuriootpa, Tanunda, Lyndoch and Rowlands Flat. It is noted for its wine production and is important as a fruit and vegetable producer as well as its canning, quarrying and chemical industries. A mediterranean type climate of dry hot summers and moderately wet winters provides a reliable rainfall of about 22 inches a year, an average yearly total of about 55 x 10(9) gallons for the Catchment Area which is drained by the North Para River and its tributaries. The River flows out of the Valley through a gauging station which has had an average measured yearly flow of 3.6 x 10(9) gallons since 1939. The Valley is a basin in Torrensian Series and Kanmantoo rocks of the Adelaide System and has formed by a probable late Tertairy or Quaternary westerly dipping fault resulting in a steep escarpment to the east and gentle rises to the west. The basin has been partly filled with Quaternary and Tertiary Lacustrine and fluviatile sediments varying from clays to coarse gravels. The Tertiary basin deposits are frequently lignitic and may be contemporaneous (with different facies) with the lateritized and ferruginous capping of Tertiary sands, clays and gravels found on the western slopes of the basin. The basin sediments are somewhat lenticular and, therefore, together with the varying topography drainage and form of the basin, present a complex hydrological system. The sediments are generally well charged with water along the main drainages but are not uniformly so in either plan or depth. Near the main drainages, bores have produced good supplies of good quality water where favorable aquifers have been penetrated - particularly in the Nuriootpa - Light Pass area. At other points less permeable beds yield poor supplies. Bores and wells in Tertiary outcrops on the western margins of the Valley have produced small supplies of high salinity water. Areas of shallow alluvium and Adelaide system rocks vary in their capacities to produce underground water, depending upon the local conditions of drainage and permeability. Surface runoff waters entering the Valley are thought to suffer relatively little loss through lateral percolation into the tight Adelaide System Rocks, and that part which does not flow out of the Valley is largely lost through evaporation and transpiration. To preserve the present storage of underground water and salinity conditions, increased utilisation must be accompanied by increased recharging of the aquifers. The amount of water available for this purpose is of the order of that measured by the flow of the River through the gauging station. Only a portion of this amount will enter the underground storage depending upon the favorability of recharge conditions. Although the area is largely served by reticulated reservoir water, such water is insufficient for irrigation and industrial requirements, and increased demand for underground supplies may be expected.