Application of the Water Quality Guidelines to groundwater

The ANZECC/ARMCANZ (2000) Water Quality Guidelines outlined linkages to groundwater, which remain applicable under the ANZG (2018) Water Quality Guidelines. Groundwater is an essential water resource for many aquatic, riparian and terrestrial ecosystems. For substantial periods, groundwater can be the sole source of water to some rivers, streams and wetlands. Groundwater is also very important for primary and secondary industry as well as for domestic drinking water, particularly in low rainfall areas with significant underground aquifers. Generally, the Water Quality Guidelines should apply to the quality of both surface water and of groundwater, since the community values which they protect relate to above-ground uses (e.g. irrigation, drinking water, farm animal or fish production and maintenance of aquatic ecosystems). Hence, groundwater should be managed in such a way that when it comes to the surface, whether from natural seepages or from bores, it will not cause the established water quality objectives for these waters to be exceeded, nor compromise their designated community values. In addition to this, underground aquatic ecosystems and any novel fauna also need to be protected. Relatively little is still known of the lifecycles and environmental requirements of groundwater communities. Where potentially high conservation values are identified, the groundwater upon which the communities depend should be afforded the highest level of protection, at least until further knowledge is gained. Basing groundwater quality objectives on data from groundwater reference condition locations is recommended to achieve this protection. It is important to note that different biological, physical and chemical conditions and processes operate in groundwater compared with surface waters, and these can affect the fate and transport of many chemicals. This may have implications for the application of guideline values and overall management of groundwater quality.

Australian guidelines for groundwater quality protection

Since ANZECC/ARMCANZ (2000), additional national guidance has been provided in the Guidelines for groundwater quality protection in Australia (Australian Government 2013). The groundwater guidelines re-confirm the significance of groundwater resources for human and ecosystem requirements, noting that:

‘Protection of groundwater quality is imperative to ensure the protection of healthy ecosystems and maintenance of environmental values as well as for future economic and population growth.’

The groundwater guidelinesset outa risk-based framework, consistent with the national water quality management framework, that can be implemented within existing jurisdictional policy and legislation to protect and enhance groundwater quality in Australia to support the associated community values.

Practical applications of the guidelines include the characterisation of groundwater resources, the identification of groundwater quality objectives and the development of specific groundwater protection mechanisms. The intention is that state and territory governments will take these guidelines into account when developing policies and legislation to protect the groundwater quality of each water resource, thus maintaining or enhancing the associated community values and preventing contamination within their respective jurisdictions. The groundwater guidelines do not provide guideline values for toxicants in groundwaters, but rather provide guidance on how existing default guideline values (DGVs) for other community values (e.g. aquatic ecosystems, drinking water, livestock drinking water, irrigation water) might be applied, or where new guideline values might need to be derived, in order to inform the setting of appropriate water quality objectives. For example, where groundwater fauna (e.g. stygofauna) need to be protected, DGVs for surface water ecosystem protection could be applied in the absence of any site-specific data that indicate the DGVs will be under- or over-protective. However, their applicability to the groundwater quality and ecosystem of interest should be carefully considered. Also, the assessment of ecosystem receptor lines of evidence is always recommended as part of a weight of evidence process to improve understanding of the impacts of toxicants in groundwaters, which would include the derivation of locally relevant guideline values. Ideally, locally relevant guideline values would be derived based on groundwater quality data from appropriate groundwater reference sites.

Other groundwater quality and ecosystem knowledge and guidance

In recognition of the key role of groundwater as a source of water, additional work has also been undertaken specifically for the management of the Great Artesian Basin (GAB), which underlies 22% of Australia. This is outlined through the Great Artesian Basin Strategic Management Plan (the Plan). The Plan intends to deliver outcomes through an adaptive, evidence-based risk management approach. Among other matters, the Plan recognises the need to protect groundwater quantity and quality in order to support groundwater dependent ecosystems and groundwater uses for communities and industry. It recommends the need for risk-based water quantity and quality monitoring as part of groundwater resource condition assessments. To do this, appropriate groundwater guideline values will be required.

In addition to the above-mentioned documents, the science around the characterisation and management of groundwater and groundwater ecosystems has significantly advanced in the past 20 years, and there is a need to better integrate this knowledge with the guidance provided for surface water quality management in the Water Quality Guidelines. In the interim, some useful publications include those by Hancock et al. (2005), Hancock & Boulton (2009), Sundaram & Coram (2009), Korbel & Hose (2011, 2017), DSITI (2017), Korbel et al. (2017) and Doody et al. (2019).

References

ANZECC & ARMCANZ 2000. Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand, Canberra.

Australian Government 2013. Guidelines for groundwater quality protection in Australia: National Water Quality Management Strategy, Department of Agriculture and Water Resources, Canberra, March. CC BY 3.0.

Doody TM, Hancock PJ & Pritchard JL 2019 Information Guidelines Explanatory Note: Assessing groundwater-dependent ecosystems. Report prepared for the Independent Expert Scientific Committee on Coal Seam Gas and Large Coal Mining Development through the Department of the Environment and Energy, Commonwealth of Australia 2019.

DSITI 2017. Using monitoring data to assess groundwater quality and potential environmental impacts. Version 1. Department of Science, Information Technology and Innovation (DSITI), Queensland Government, Brisbane

Hancock PJ, Boulton AJ & Humphreys WF 2005. Aquifers and hyporheic zones: Towards an ecological understanding of groundwater. Hydrogeological Journal 13:98–111.

Hancock PJ & Boulton AJ 2009. Sampling groundwater fauna: efficiency of rapid assessment methods tested in bores in eastern Australia. Freshwater Biology 54: 902–917.

Korbel KL & Hose GC 2011. A tiered framework for assessing groundwater ecosystem health. Hydrobiologia 661: 329–349.

Korbel K, Chariton A, Stephenson S, Greenfield P & Hose GC 2017. Wells provide a distorted view of life in the aquifer: implications for sampling, monitoring and assessment of groundwater ecosystems. Scientific Reports 7, 40702; doi: 10.1038/srep40702.

Korbel KL & Hose GC 2017. The weighted groundwater health index: Improving the monitoring and management of groundwater resources. Ecological Indicators 75: 164–181.

Sundaram B & Coram J 2009. Groundwater Quality in Australia and New Zealand: a literature review. Milestone Report. Prepared by Geoscience Australia for the Australian Government Department of the Environment, Water, Heritage and Arts, December 2009. Department of Resources, Energy and Tourism, Canberra.