Information on surface water and groundwater quantity and quality in the Gloucester subregion is documented in this product. The information was captured in October 2015 and is used in the evaluation of the potential impact of coal seam gas and coal mining development on water and water-dependent assets.
In the Gloucester subregion, coal seam gas and coal mining development may impact on water and water-dependent assets primarily in two river basins: the Gloucester river basin in the north of the subregion, and the Karuah river basin in the south.
The Gloucester River produces a mean annual flow of 550 gigalitres per year at Doon Ayre and the Karuah River produces flow of 270 gigalitres per year at Booral. These two major rivers do not host major dams or weirs, but are affected by diversion for irrigation.
For the northern rivers of the Gloucester river basin there are 84 surface water extraction licences amounting to 6806 megalitres of water, or 1.64% of the annual average flow. For the southern rivers there are 25 licences amounting to 951 megalitres, or 6.5% of the annual average flow.
Actual groundwater use data are not readily available for the Gloucester subregion due to a range of regulatory conditions. Of the 192 groundwater bores noted in October 2015, 175 have extraction licences.
In total 1864 megalitres per year of groundwater licences are allocated across the subregion. Summarising water licence allocations may underestimate the amount of groundwater used since some unmetered bores extract water from the aquifer system.
It is estimated that 2878 megalitres of groundwater is extracted across the Gloucester subregion each year. This figure includes extraction from existing coal resource development, as of October 2015.
In November 2013 the New South Wales Government commenced water quality monitoring at two sites on the Avon River, a tributary of the Gloucester River. Measurements show increasing salinity and decreasing pH with distance down the catchment.
The New South Wales groundwater bore database contains data from bores drilled in the bioregion from the early 1900s through to the present day. Despite this dataset, assessment of groundwater quality, including salinity and trace elements, over large spatial areas is difficult for the Gloucester subregion as there are only a few control points.