Since the time of European settlement water pressures within large portions of the Great Artesian Basin (GAB) have been in decline due to uncontrolled artesian flows from bores drilled for stock and domestic purposes. This problem has been exacerbated by the deteriorating condition of many of the aging bores. From the 1990s the NSW Government has been supporting the replacement or capping/piping of these bores. As part of this work, the NSW Department of Industry has initiated two projects in the NSW portion of the GAB.
The first project’s objectives are to identify conditions of the bore head and type of water distribution system; measure head, flow, temperature and water quality; estimate water requirements; and determine the source of water for GAB springs through isotopic studies. Contractors were engaged to conduct landholder interviews and undertake field assessments. The water samples for quality and isotopic analysis were collected, stored and transported to Australian guidelines and analysed by NATA registered laboratories. So far about 700 bores have been assessed.
For the second project, a consultant was engaged to model when and where artesian conditions will reoccur. A trend analysis of pressure data, partitioned into areas of approximately 50 km by 50 km in size, resulted in the development of area specific trends for the confined aquifers in the NSW portion of GAB. Information collected during the bore survey was used to refine the analysis. The trend analysis identified regions currently recovering and when and where artesian conditions can expect to be regained. Basin-wide potentiometric maps were prepared to identify bores ‘at risk’ of failure or at risk to contribute to water losses.
The data and information gained is informing the prioritisation of bore replacement and capping/piping activities, development of future infrastructure management strategies, the strategic policy in the GAB, the ongoing management of the GAB resource, and the remake of Water Sharing Plan for the NSW GAB Groundwater Sources.