International Association of Hydrogeologists Australia

The use and abuse of the precautionary principle

Wednesday 24 July, 2013

The NSW Protection of the Environment Administration Act (PEAA) 1991, provides the following definition of the Precautionary Principle (PP): “If there are threats of serious or irreversible environmental damage, lack of full scientific certainty should not be used as a reasoning for postponing measures to prevent environmental degradation.”

The PP is routinely applied in Groundwater Management. In this context, implementation of the PP typically involves a conservative approach to large-scale management of the resource in which sustainable diversion limits (SDLs) are more likely to be underestimated than overestimated.  For example, in the Murray Darling Basin (MDB), extraction limits for confined aquifers have been based on output from models which simulate the impacts of future groundwater extraction and which have uncertainty associated with them. The sustainable extraction rate derived from the model is scaled down based on model uncertainty to provide an extraction limit that incorporates a “factor of safety”.

On a more local scale, the PP is often applied in decisions about individual groundwater licence applications to account for uncertainty in characterisation of the local hydrogeology. However, there is always some uncertainty. Thus, the decision as to whether the PP should be applied for any particular licence application is somewhat subjective.

It is important not only to manage groundwater resources both regionally and locally in a sustainable manner but in a manner that also ensures they are not unnecessarily locked up. This is recognised in the recently published Sustainable Water Strategies (SWS) in Victoria.

The NSW (PEAA) 1991 also states “In the application of the principle… decisions should be guided by: (i) careful evaluation to avoid, wherever practicable, serious or irreversible damage to the environment; and (ii) an assessment of risk-weighted consequence of various options”.

Rather than routinely applying the PP to conservatively estimate sustainable extraction limits on a whole-aquifer scale or to account for uncertainty in local licence applications, it is important to assess the consequences/risks of both underallocation and overallocation and to facilitate adaptability in management of the resource. In the MDB example above, the consequences would be quite different.



Associate Professor John Webb, La Trobe University

Alan Wade, Principal Hydrogeologist, Aquade Groundwater Services


Come Join Us

Date: 6th August 2013

Time: 5:30pm for a 6pm start

Location: RMIT, Academic Building 80 Rm: 80-09-12 (Level 9)

(located at 445 Swanston Street, on the west side of Swanston Street)


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