This bioregional assessment helps us understand how coal seam gas and coal mining development could affect water resources and water-dependent assets in the Central West subregion, which is part of the Northern Inland Catchments bioregion. It identifies where potential impacts could occur, as well as the areas that are unlikely to be affected.
About the subregion
The main rivers in the Central West subregion are the Macquarie, Castlereagh and Bogan rivers of the Murray-Darling Basin. The subregion extends from the plains around Dubbo across the low-lying plains of the Macquarie and Castlereagh river systems north-west to the Barwon River floodplains. The main cities and towns for the subregion are Dubbo, Coonabarabran, Coonamble, Gilgandra and Nyngan. Most of the land in the subregion is used for agriculture (grazing and cropping).
The subregion contains seasonal, semi-permanent and permanent wetlands and lagoons, including the Macquarie Marshes which is an internationally recognised and protected wetland. The subregion is home to a number of water-dependent ecological communities, and plant and animal species which are listed as endangered or critically endangered under NSW and Commonwealth legislation.
Coal mining and coal seam gas operations
The subregion is underlain by rocks of different ages that belong to three geological basins: the Sydney, Gunnedah and Surat basins. The coal-bearing Sydney and Gunnedah basins underlie the eastern and south-eastern parts of the subregion. Coal mining currently only occurs at Ulan (in the northern part of the Western Coalfield in the Sydney Basin). A major coal deposit has been identified at Cobbora (proposed open-cut coal mine), but little exploration activity has been undertaken across the rest of the two basins within the subregion. The area of the Surat Basin, which underlies most of the subregion, has currently little potential for coal mining.
In the Central West subregion coal seam gas exploration has only occurred in rocks of the Gunnedah Basin. This exploration has shown that although there may be gas present in the coal seams, it is uneconomic to develop for commercial production. As of October 2014 there were no coal seam gas developments planned or proposed in the Central West subregion.
About the bioregional assessment
The bioregional assessment for the Central West subregion includes compiling background information, a water-dependent asset register and a data register. Results from this work have shown that there is unlikely to be further coal and coal seam gas development in the Central West subregion. For these reasons, the bioregional assessment will not include further analysis such as model-data, impact and risk analyses. Instead, further work will be done in other subregions in the Northern Inland Catchments bioregion where a greater level of coal and coal seam gas development is expected. Any impacts from the Ulan Coal Mine will be primarily assessed in the Hunter bioregional assessment. The information collected for the Central West subregion may be used for future assessments or environmental studies.
- Area: 46,735 square kilometres
- Population: about 80,000
- Climate: varies from hot and dry (north-west) to temperate to sub-tropical (east)
- Annual rainfall: 520 millimetres
- Lake Eyre Basin bioregion
- Northern Inland Catchments bioregion
- Clarence-Moreton bioregion
- Northern Sydney Basin bioregion
- Sydney Basin bioregion
- Gippsland Basin bioregion