Perth: Future outlook
Future prospects
This section looks forward 12 months and considers what water assets, claims, and commitments might affect the region's water resources.
Table N39 shows that there is a deficit of available water assets and future water rights over water liabilities and future water commitments that are expected to be settled within 12 months of the reporting date.
| Volume ML | |
| Total water assets as at 30 June 2015 | 209,854 |
| less water assets not available to be accessed, taken, or delivered: | |
| dead storage | (22,250) |
| conveyance water | (7,102) |
| less total water liabilities as at 30 June 2015 | (117,530) |
| Subtotal | 62,972 |
| less future commitments expected to be settled within 12 months of the reporting date | |
| expected diversion of surface water | (191,268) |
| expected extraction of groundwater | (403,581) |
| Surplus/deficit of available water assets over water liabilities and future commitments expected to be settled within 12 months of the reporting date | (531,877) |
| add expected inflows within 12 months of the reporting date | |
| net precipitation/storage inflow | 150,000 |
| expected delivery of desalinated water | 120,000 |
| expected inter-region inflow | 2,000 |
| Surplus/deficit of available water assets and expected future inflows over water liabilities and future commitments expected to be settled within 12 months of the reporting date | (259,877) |
The expected diversions and extractions are based on abstractions made during the 2014–15 year; however it is expected that the increase in use of desalinated water will continue, reducing dependence on surface water and groundwater resources for urban water supply.
According to the Bureau of Meteorology's Climate outlook, it is expected to be a relatively dry wet season across the region. Based on previous years' data, this is expected to result in evaporation from the storages exceeding precipitation and river inflows into the storages.
Future direct rainfall on and runoff to the watercourses together with groundwater recharge within the Perth region that could not be estimated for the 2014–15 year should contribute to meeting the region's water demands, along with desalinated water.
The total water assets in Table N39 only represents total water in the surface water store at 30 June 2015. Groundwater assets are not included because the volume of water in aquifers could not be quantified (see Groundwater note).
Contingent water assets and contingent water liabilities
Contingent water assets
The Department of Water sets extraction limits on groundwater aquifers to protect groundwater-dependent ecosystems. Only water above the prescribed minimum water table level is recognised as a water asset in the account. The volume of water that is beyond this extraction limit is considered a contingent water asset for aquifers in the region; however, similar to the recognition of groundwater assets, there is currently not enough information available regarding groundwater resources in the Perth region to allow for a volumetric estimate.
Contingent water liabilities
There are no contingent water liabilites in the Perth region.