Rick Van Dam provided an introduction to the water quality management framework and weight of evidence approach. The purpose of this framework is to draw in all water quality management activities under one framework and link out to relevant guidance at each step. Previously the ANZ WQG (ANZECC 2000) relied heavily on chemical assessment to determine whether or not the guideline value has been exceeded, using weight of evidence you can evaluate a combination of different qualitative, semi-quantitative or quantitative lines of evidence to make an overall assessment of the water/sediment quality. An additional benefit if the new ANZG framework is that it is web-based, allowing for updates of guideline values and suggested management approaches as new information becomes available.
Kristen Broadgate gave an overview of the revised methodology for deriving aquatic ecosystem guidelines, which ties in nicely with weight of evidence in the water quality management framework. Guideline values are based on species sensitivity distributions (using Burrlioz software) with a shift towards use of more input data of higher quality.
Paul Leahy spoke about the adoption of the ANZ Water Quality guidelines in Victoria. SEPP Waters also adopts a similiar risk-based, weight of evidence approach of the ANZ WQGs. Non-toxicant water quality values (ecosystem stressors) will continue to be state-derived. Whilst SEPP Waters currently refers to the ANZECC 2000 guidelines, it is expected that ANZG guidance is used in preference (this will likely be amended with the new Environment Protection Act which arrives in 2020).
How can things be done better as a result of this discussion:
Guidelines are just guidelines and shouldn’t be so heavily relied on in isolation. The DGVs are just one of many lines of evidence and other factors such as pressors, stressors and ecosystem receptors should be assessed as part of your weight of evidence approach to water quality management.
Didn't get to attend the event, but would love to review the presentations - go to the ALGA online library* type in search words "ANZ Guidelines"