Site-specific guidelines and Body-burden responses

C.W. Hickey

The new risk-based water quality guidelines published jointly by the Australian and New Zealand Environment and Conservation Council (ANZECC) and the Agricultural and Resource Management Council of Australia and New Zealand. The ANZECC (2000) guidelines differ from the earlier (ANZECC 1992) guidelines in the method for derivation of numeric criteria and in provision for use of a range of management approaches. Implementation of the new guidelines presents challenges in relation to the Resource Management Act (RMA) 1991 and Hazardous Substances and New Organisms (HSNO) Act 1996.

One of the key features of the new guidelines is the provision of a framework where users can refine the guidelines to suit their local environment, i.e., develop site-specific guidelines. This marks a significant move away from the 1992 guidelines where a single number was advocated across not only different ecosystems, but also the huge diversity of landscapes found in Australia and New Zealand.

The main purpose of the guidelines is "to provide an authoritative guide for setting water quality objectives required to sustain current, or likely future, environmental values (uses) for natural and semi-natural water resources in Australia and New Zealand". The guidelines are not mandatory standards; however, they should become an authoritative reference for water quality management, especially for toxic contaminants.

The focus is on the issues.

The new guidelines recommend you choose an issue (e.g., toxicity) and then work out the environmental processes that contribute to it, rather than focusing on a single indicator (e.g., copper). Once this has been done, you can decide which water quality indicators to use and what guidelines to follow. The guidelines have been divided up into different issues with 'packages' of indicators related to each issue. Some examples of guideline packages include: effects due to toxicants in sediments; effects due to temperature changes; and effects due to pH changes.

There are more ecosystems.

Rather than lumping aquatic ecosystems into freshwater and marine, the new guidelines now recommend up to six ecosystem types: upland rivers and streams, lowland rivers, freshwater lakes and reservoirs, wetlands, estuaries, and coastal and marine. These categories will probably be refined even further as more information comes to hand. Three types of ecosystem conditions are also now recognised, each with its own level of protection: high conservation/ecological value systems; slightly to moderately disturbed systems; and highly disturbed systems.

The guidelines can be applied to local conditions.

Unfortunately it is not possible to have a universal set of specific guidelines that will apply equally to all the different ecosystems in New Zealand and Australia. The ANZECC has, however, developed a series of risk-based decision frameworks where we will be able to refine the guidelines to suit local environmental conditions, i.e., make the guidelines site-specific. These frameworks are based on guideline 'trigger values' which are concentrations of a chemical or nutrient that have the potential to cause a problem if exceeded, and so trigger a management response. If the level of a particular chemical or nutrient does not meet the water quality guidelines (i.e., exceeds the trigger values), one has the option of getting more information to determine whether the trigger values are suitable or whether they need to be changed. It may be more time consuming refining the guideline trigger values, but one may also produce more realistic management guideline values.

How do trigger values translate to the RMA?

Trigger values for chemical stressors are provided for differing levels of nominal aquatic community protection (e.g., 99%, 95%, 75%). Guidance has been provided (Hickey & Pyle 2001) in interpreting the trigger value thresholds relative to the RMA narrative guidelines. The trigger values for 99% protection relate to the narrative "no adverse effects" and would apply to protection of pristine areas, with a 95% value applying to a "no significant adverse effect" guideline. Further discussion is provided in that publication relating to the situations applicable to implementation of trigger values for lower protection levels.

What is the relevance to contaminated sites?

Contaminated sites represent a wide range in their potential for leaching of chemicals to the receiving environment. For this reason, they frequently require site-specific considerations for management and implementation of monitoring programmes. For example, contaminant exposure by aquatic organisms may occur through various routes. These include continuous release to a riverine environment, resulting in chronic exposure conditions, or discharge relatively high concentrations during rainfall events, resulting in acute (short-term) exposures. The ANZECC guidelines provide trigger values for chronic exposure (but not acute exposure) and provide guidance on other approaches such as toxicity testing and biological monitoring.

How do I get more information?

The New Zealand Ministry for the Environment operates a frequently asked questions section of their web page (www.mfe.govt.nz) relating to the ANZECC guidelines.

These guidelines provide an authoritative reference for water quality management in New Zealand - particularly for toxic contaminants - and are a big step forward in helping us manage water quality. 

A comprehensive document providing guideline values for toxicants, physical and chemical stressors, etc. Includes guidelines for sediment quality, agricultural water use, biological indicator methods, etc.

Available in printed form or to download from the MfE web site in individual chapters.

References

ANZECC. (1992). Australian water quality guidelines for fresh and marine waters. Australian and New Zealand Environment and Conservation Council, Canberra, Australia. 

ANZECC & ARMCANZ. (2000). Australian and New Zealand guidelines for fresh and marine water quality. October 2000. National Water Quality Management Strategy Paper No 4, Australian and New Zealand Environment and Conservation Council & Agriculture and Resource Management Council of Australia and New Zealand, Canberra, Australia.

Hickey, C.W.; Pyle, E. (2001). Derivation of water quality guideline values for heavy metals using a risk-based methodology: An approach for New Zealand. Australian Journal of Ecotoxicology 7: 137-156.