- Bioregional Assessment Program
- Hunter subregion
- 3-4 Impact and risk analysis for the Hunter subregion
- 3.5 Impacts on and risks to water-dependent assets
Ecological water-dependent assets
Of 1652 ecological assets in the register of water-dependent assets, 731 are in the zone of potential hydrological change and 603 are associated with the following potentially impacted landscape classes: forested wetlands, wet or dry sclerophyll forests, permanent or perennial streams, or lowly to highly intermittent streams. The 921 assets outside the zone, which are very unlikely (less than 5% chance) to be impacted, include 2 Ramsar-listed wetlands, 13 Directory of Important Wetlands Australia (DIWA) wetlands, 12 Commonwealth- or state-listed vegetation communities, 2 Important Bird Areas, 48 nationally listed (Collaborative Australian Protected Area Database (CAPAD)) parks and reserves, and potential habitats for 14 Commonwealth- or state-listed species.
Of the 731 assets in the zone that are associated with potentially impacted landscape classes, 210 meet criteria for potential hydrological impact that identifies them as ‘more at risk of hydrological changes’ from additional coal resource development than other assets within the zone. ‘More at risk’ assets are deemed to be those where there is at least a 50% chance of the modelled hydrological change exceeding certain defined thresholds for the hydrological response variables relevant to the landscape class with which the asset is associated. An asset was deemed to be associated with a landscape class if it shares an assessment unit with that landscape class, except for species and vegetation communities, whose association with landscape classes were based on knowledge of the ecology of the species or community.
No DIWA wetlands nor threatened ecological communities were identified as ‘more at risk of hydrological changes’.
One state-listed vegetation community, 3 Important Bird Areas, 5 nationally listed (CAPAD) parks and reserves, and potential habitats for 23 Commonwealth- or state-listed species were amongst assets identified as ‘more at risk of hydrological changes’ due to additional coal resource development. These included the Hinterland Spotted Gum Endangered Ecological Community, Lake Macquarie Important Bird Area, Goulburn River National Park, Wollemi National Park and the potential habitats of two iconic species: the koala and the malleefowl. However, owing to the large size of most assets and the relatively small areas potentially impacted, the potential impact on any individual asset is likely to be small.
Based on receptor impact modelling, the potential impacts on ecological assets associated with riverine landscape classes are only likely in small stream reaches associated with large hydrological changes. There is potential for impacts on ecological assets associated with groundwater-dependent ecosystem (GDE) landscape classes in locations where there is significant groundwater drawdown.
Economic water-dependent assets
There are 5 groundwater sources potentially impacted by hydrological changes due to additional coal resource development. Twenty-four surface water sources intersect the zone, however, the intersection of 5 of these 24 surface water sources is an artefact of the analysis technique and is associated with just eight extraction points. Therefore, only 19 of these surface water sources are potentially impacted by hydrological changes due to additional coal resource development. Fifteen surface water sources and four groundwater sources are very unlikely to be impacted due to additional coal resource development. Note that these economic assets do not correspond with those in the asset register as they were based on the old water sharing plans, whereas the analysis in this product uses the current water sharing plans.
There are 3911 groundwater bores and surface water extraction points in the zone that are potentially impacted due to additional coal resource development. Just over half are associated with the Hunter Regulated River water source, 32% with unregulated and alluvial water sources and 15% with non-alluvial groundwater.
The change in water availability (indicated by the change in mean annual flow) is very likely (greater than 95% chance) to exceed 5 GL/year in the Hunter Regulated River at Greta, but very unlikely to exceed 12 GL/year (1.6% of baseline mean annual flow). In unregulated and alluvial water sources, there is the possibility (at least 5% chance) of reductions in water availability of 3 to 6 GL/year in the Singleton, Muswellbrook, Jerrys and Wyong River water sources.
Potentially significant changes in reliability of supply (as indicated by change in number of cease-to-pump days) are possible for some creeks in the Singleton, Jerrys and Muswellbrook water sources, and in the Wyong River. In the Wyong River, the median change over the three 30-year periods is modelled to be between 6 and 8 days, with a 5% chance of 145 days per year in 2043 to 2072.
Of the 1450 bores in the zone, there is a 5% chance that 170 have drawdowns exceeding 2 m, the minimal impact consideration threshold for water supply works under the NSW Aquifer Interference Policy, at which point ‘make good’ provisions should apply. Of these, 159 are on mining and exploration leases where the predicted drawdowns are considered less likely to lead to an economic impact. The requirement to ‘make good’ on potential economic impacts to licence holders is considered more likely for the remaining 11 bores, which provide access to water in the Sydney Basin – North Coast groundwater source (7) and Jilliby Jilliby Creek (2), Tuggerah Lakes and South Macquarie Lake water sources.
Sociocultural water-dependent assets
Of 307 water-dependent assets in the water-dependent asset register for the Hunter subregion, 5 assets within the ‘Social’ subgroup and 62 assets within the ‘Cultural’ subgroup intersect with the zone of potential hydrological change. Thus it is very unlikely that hydrological changes associated with coal resource development affect the remaining 240 sociocultural assets. Of the sociocultural assets that intersect with the zone, 45 are built infrastructure and were not assessed. The remaining 22 sociocultural assets are reserves or national parks composed of a range of water-dependent landscape classes.
There are three National Heritage-listed areas within the zone of potential hydrological change in the Hunter subregion as well as the Greater Blue Mountains World Heritage Area. Any impact on these assets is predicted to be minor.
Product Finalisation date
- 3.1 Overview
- 3.2 Methods
- 3.3 Potential hydrological changes
- 3.4 Impacts on and risks to landscape classes
- 3.5 Impacts on and risks to water-dependent assets
- 3.6 Commentary for coal resource developments that are not modelled
- 3.7 Conclusion
- Contributors to the Technical Programme
- About this technical product