Water entitlement and allocation policies and institutions to assist managed aquifer recharge contribute to water security in Australia

Peter Dillon b and John Ward a
CSIRO Water for a Healthy Country Flagship Program, Australia
a CSIRO Sustainable Ecosystems, Brisbane
b CSIRO Land and Water, Adelaide

Australian states and territories have water resources management policies and legislation that require water access entitlements and introduce mechanisms for allocating water resources between different water uses and the environment.  They also have regulations on licensing of drillers, issuing entitlements to extract groundwater, and some have experience in reducing allocations where entitlements exceed sustainable supply capacity of an aquifer system.  However few have integrated policies or regulations concerning managed aquifer recharge, for example licensing of MAR operators, issuing water entitlements to urban stormwater and wastewater, issuing entitlements to storage space in aquifers, and providing conditions and protections to operators for storing and recovering water using aquifers.  Having fundamental policies would improve confidence for private sector investment in MAR. Importantly, methods for transferring entitlements to groundwater are needed if MAR is to play a major role in sustaining groundwater supplies from heavily exploited aquifers and in the face of climate change. 

Managing recharge in an aquifer where abstraction is unmanaged provides no assurance that groundwater level or pressure objectives can be achieved.  Regulation of a legion of users and rechargers of small volumes of groundwater is highly inefficient and difficult. New instruments need to be found to simplify management. This could involve methods to engender collective responsibility to prevent groundwater depletion, high water tables and pollution and to encourage awareness, monitoring and consolidated reporting. Groundwater users associations are one vehicle to democratise groundwater management where government agencies have been ineffective alone.  Standardised approvals for new wells requiring offsetting rainwater MAR operations could also help to restore groundwater equilibrium.

More severely, in those rural source water catchments where demand exceeds supply and environmental flow requirements have been established but are not being achieved, establishment of MAR projects would inevitably lead to accelerated environmental degradation by reducing downstream flows. A possible exception is where introduction of MAR would reduce total diversions and evaporation losses from off-stream surface storages and it could be clearly demonstrated that MAR would increase environmental flows.

In most urban and peri-urban areas, where impervious surfaces have increased runoff, entitlements to stormwater and reclaimed water are unclear.  This may impede long term strategic investment in water recycling via aquifers.  By introducing water entitlements that are clearly defined, communicated and implemented, MAR has the potential to minimise environmental harm and even provide environmental benefits while improving overall system integrity and management. 

End uses of recovered water also need consideration, as otherwise all aquifer storage capacity may be allocated to commercial projects aimed at withdrawing most water in the year following recharge.  Greater community benefit may be derived by strategically storing some water to be available as drought and emergency supplies when other resources are depleted.  Allocation of storage in relation to use, conditions on uses of recovered water, or scarcity pricing mechanisms are possible ways to maximise the value of both recharged water and of aquifers.   This will need to recognise the quality of water on recovery and its suitability for the required uses, and in turn, this will depend on the properties of the aquifer and the quality of recharged water.  

A framework for regulation of MAR in urban and rural areas, consistent with the national water reform agenda has been outlined for consideration by water resources managers through the National Groundwater Advisory Committee, and is reported in this paper. This follows the principles of robust separation of entitlements and allocations that have been successful in guiding rural water reform. 

Aquifer characteristics may determine entitlements to store as well as recover and the spatial extent of transferability of entitlements.  For example the proportion of water that may be recovered, the length of time over which recharge credits may accrue, the distance and direction over which allocations may be transferred will depend on local hydrogeology the location of cones of depression and the salinity of the aquifer and proximity to other users and groundwater-dependent ecosystems.

Finally, the paper refers to a new type of institution, called a Water Bank in Arizona, that may provide effective processes to match investment to address future water needs making use of MAR from various sources and other alternatives under changing demographic and climatic conditions.