ANZECC water quality guidelines - FAQs
4. What is the 'risk-based' approach and how does it work; what was wrong with the earlier (1992) Guidelines' approach?
The new approach will add to the costs of water quality management. The approach taken in these hierarchical decision frameworks is to provide guideline trigger levels (equivalent to the old guideline default values) that refer to the concentration of the chemical available for uptake by organisms. Guideline trigger levels are concentrations that, if exceeded, would indicate a potential environmental problem, and so 'trigger' further investigation. This investigation would refine a guideline value by accounting for environmental factors that can modify the effect of the chemical. The old Guidelines also recommended refinement for local conditions, but did not provide the guidance on how this could be done. The new decision frameworks are only required if trigger values are exceeded and stakeholders agree that refinement is necessary. Although in some cases this will require more work, it will result in much more realistic goals for management and therefore has the potential to reduce costs for industry. For industry in particular, it may well be cost effective to implement the decision frameworks if trigger values are likely to be exceeded. Then, there is the opportunity to determine a locally-relevant value that may be more relaxed once the unique, site specific factors are taken into account - this in turn will reduce unnecessary discharge treatment costs.
