The scarcity of surface water in South Australia has resulted in heavy reliance on groundwater across the state. In many of SA’s 21 prescribed groundwater areas, water allocation plans (WAPs) provide the framework for sustainable management of groundwater resources.
The South Australian Natural Resources Management Act (the Act) guides the development of WAPs and requires an assessment of the water available in the prescribed area - the resource capacity, to meet the needs of environmental water requirements and consumptive demand.
Historically there has been a view that a WAP must assign a fixed volume to these components. This resulted in a number of issues which result in over-allocation of the groundwater resources. Prior to amendments made to the Act in 2009, there was no opportunity to vary water quantities identified in WAPs without undertaking a Ministerial amendment or a costly unscheduled WAP review. This led to a tendency to be overly generous with the water quantities estimated and often, in the absence of sufficient data, to rely on expert intuition to estimate volumes.
The 2009 amendments to the Act provide the ability for a WAP to acknowledge that it represents the best available science, but that as the resource and our knowledge of it changes, so too can the volume of water available and the volume allocated. The amendments allow WAPs to adaptively manage resources through annually announced allocations and allow the assignment of new volumes of water for consumptive purposes if additional science identifies there is more water available than previously assessed. These legislative changes mean that WAPs are no longer based on an expectation of complete knowledge of a complex, varying resource, but rather have the ability to respond to changes in the resource and our understanding of it, that may occur during its 10 year life span.