The Naracoorte Ranges Prescribed Wells Area (PWA) is 300 km SE of Adelaide, and covers about 2400 square km. The PWA consists of a low-lying interdunal flat in the SW, and an elevated highlands area in the NE, separated by the Kanawinka Fault. The unconfined and confined aquifers are both present and the main water resource is the regionally unconfined Gambier Limestone Formation aquifer in the Naracoorte highlands. Beneath the interdunal flat, groundwater flow is generally through the Padthaway and Bridgewater Formations. Salinity ranges between 900 and 2500 mg/L. Well yields range from 50 to 100 L/s. The unconfined and confined aquifers are separated by a relatively thick, low permeability aquitard, and can be managed independently. The confined aquifer is used only for the Naracoorte town water supply. Salinity is around 1200 to 1400 mg/L. The PWA was proclaimed in 1986 following the passing of the Groundwater Border Agreement Act 1985. An additional area was also included so that the western boundary adjoined the Padthaway PWA. In 1993, the PWA was expanded to include the Naracoorte Plains (Hundreds of Naracoorte and Robertson). The total allocation for the 1998/1999 season was 77 871 ML and water use was estimated to be 38 982 ML, about half of the total allocation. The accuracy of this figure is debatable, as the water use figure is not the actual volume extracted, but an estimate of crop water usage. There are currently 73 observation wells in the water level monitoring network. There are two salinity monitoring networks, a Government operated network and a private irrigation network. The combined total of observation wells is 79. Generally the networks are adequate. In the highlands, water levels are rising by up to 26 cm/yr. Hydrographs show the greatest rise has occurred since the early 1980s, due to clearance of native vegetation by early European settlers, and the failure of lucerne crops in the mid-1970s. Associated with the rising water table is an increase in salinity. The depth to water in the areas where the highest increase has occurred is now about 15 to 20 metres. At the present rate of increase, water levels are unlikely to have any significant affect on the water resource. The increase in groundwater salinity, while currently acceptable, may have long-term implications. The impact that the use of water from one resource may have on another resource was considered in the following situations: - the impact of using surface waters to artificially replenish the groundwater system. - the impact that taking groundwater from the unconfined aquifer may have on the confined aquifer. - the impact that taking groundwater from the confined aquifer may have on the unconfined aquifer. None of the scenarios were considered to have significant impacts on the water resource, or across water management boundaries.