Water quality guidelines

Water quality guidelines are technically-derived numerical measures (e.g. concentrations) or descriptive statements to protect aquatic ecosystems and human water uses and values (e.g. irrigation, stock watering, recreation). The guidelines can be derived for a range of physico-chemical, biological and habitat indictors based on best-available science.

Australian and New Zealand Guidelines for Fresh and Marine Water Quality

The Australian and New Zealand Guidelines for Fresh and Marine Water Quality – 2018 edition are now available.

The revised Australian and New Zealand Guidelines for Fresh and Marine Water Quality are a joint initiative between the Australian and New Zealand governments and the Australian state and territory governments. They form part of the National Water Quality Management Strategy a joint national approach to improving water quality in Australian waterways.

While the updated national guidelines include default guideline values for physical and chemical stressors, local water quality information still applies as the first reference point. In Queensland this includes:-

  1. Environmental Protection Policy (Water and Wetland Biodiversity) scheduled environmental values (EVs) and water quality objectives (WQOs) available from the Environmental Protection Policy (Water and Wetland Biodiversity) web page.
  2. End of catchment anthropogenic pollutant reduction targets in Great Barrier Reef catchments contained in the Reef 2050 Water Quality Improvement Plan 2017–2022 *Anthropogenic pollution means pollution that’s caused by human activity.
  3. Queensland water quality guidelines (in the absence of EPP (Water and Wetland Biodiversity) scheduled values). See availability.
  4. Water monitoring protocols contained in the Queensland Monitoring and Sampling Manual (2018).

The 2018 national guidelines include:

  • an updated and expanded water quality management framework
  • a revised method for deriving toxicant default guideline values (‘DGVs’ - formerly called ‘trigger values’)
  • new or revised toxicant DGVs (under development using the new derivation method)
  • new physical and chemical stressor information and default guidelines values for more regions
  • a weight-of-evidence approach to water quality assessment and management
  • more information on Indigenous cultural and spiritual values
  • improved monitoring guidance.

The process of establishing new DGVs for toxicants is outlined on the national water quality guidelines website. Toxicant draft DGVs developed in accordance with the national requirements will be publicly released for a three month period on the national water quality guidelines website, during which submissions can be made. Unless new peer reviewed scientific and/or technical information justifies a re-examination, they will become final guidelines at the end of the three-month release period. When finalised, the toxicant DGVs can be used where site-specific guideline values have not been derived.

Submission /contact details

Refer to the national water quality guidelines website for further information and details on making a submission.

How water quality guidelines support waterway uses and values

Waterway uses and values (also called ‘environmental values—EVs’) include aquatic ecosystems; primary industries; recreational use; drinking water supply; industrial water; and cultural and spiritual values.

Each of these EVs requires its own specific set of guidelines because the acceptable guideline values to support one type of EV may not be acceptable to maintain another EV. For example, the guideline values for pesticides required to protect fish and other fauna are usually lower than those required to protect irrigated crops. Another reason is that the indicators relevant to one EV may be different to those used for other EVs.

Guidelines for human use EVs are almost all expressed as a single value of an indicator that applies uniformly across Australia (e.g. salinity guidelines for crops in Queensland are the same as those in West Australia). Human use EV guidelines are also dominated by physico-chemical indicators. As a result, these guidelines are relatively simple in concept and application. Water quality guidelines for aquatic ecosystem protection are considerably more complex, because:

  • aquatic ecosystem protection guidelines for some indicators (e.g. nutrients, chlorophyll-a, biological) need to be specific to different regions (e.g. Wet Tropics versus South East Queensland) because there are natural variations in their values
  • within each region, aquatic ecosystem protection guidelines for some indicators (e.g. nutrients, chlorophyll-a, biological) need to be tailored to different water types (e.g. fresh waters, estuaries, coastal and marine waters, lakes and reservoirs) because they have naturally different values of these indicators. As there are different flora and fauna in these water types, guidelines for toxicant indicators may also have to be tailored (e.g. coral reefs may be more sensitive to some pesticides than inshore or freshwater flora and fauna)
  • the Australian and New Zealand Guidelines for Fresh and Marine Water Quality specify three different levels of aquatic ecosystem protection (high ecological value, slightly to moderately disturbed, highly disturbed), for which different guideline values may need to be derived.
  • The need to develop aquatic ecosystem guidelines for more localised regions and water types is one of the main reasons why the Queensland Water Quality Guidelines (see availability) were developed. These are aimed at developing and capturing regional and local data to a degree that is simply not possible in national guidelines.

The process of developing guidelines

Information on the process of deriving water quality guidelines in Queensland is contained in the DRAFT Guideline Deciding aquatic ecosystem indicators and local water quality guidelines under the Environmental Protection (Water) Policy 2009 (PDF, 1.4MB) .

The Australian and New Zealand Guidelines for Fresh and Marine Water Quality recommend two main approaches to developing guidelines:

Guidelines based on direct impact studies

This approach is best suited to the development of guidelines for physico-chemical indicators. It relies on development of a relationship between the indicator and the EV in question. Examples of this would include impacts of:

  • salinity on crops
  • blue-green algae on humans or stock
  • toxicants or low dissolved oxygen on biota
  • reduced light penetration on seagrass growth.

Based on known relationships, we can determine an acceptably safe level of the instream pressure indicator and use this as a guideline value. Developing guidelines using this approach requires a high level of technical expertise and resources. Therefore, this approach is usually confined to universities or other research organisations.

Guidelines using reference sites/local data

For many aquatic ecosystem indicators, guidelines are developed using a referential approach. This approach is best suited to biological indicators (e.g. macroinvertebrate diversity) or to physico-chemical indicators (e.g. nutrients) where there are no simple direct-impact relationships.

Using a referential approach, guideline values for a particular indicator are determined by the condition of that indicator in a relatively undisturbed system (where available). This becomes the reference condition.

The actual guideline value is calculated on the basis of maximum acceptable departure from reference condition, according to the current and desired ecosystem condition. For moderately disturbed systems, the default acceptable departure suggested in the Australian and New Zealand Guidelines for Fresh and Marine Water Quality is that the guideline value be based on the 20th and/or 80th percentile (whichever is most appropriate for the indicator) of values at the reference site.

The QWQG (QWQG 2009, Section 4.4.2,) includes a list of criteria for reference sites, however it notes that:

Although the criteria…are recommended, there are some regions and some water types where it may be difficult to find any sites that fully comply with these criteria. In this situation it may be necessary to use lesser quality or best available sites’

Further Information on the process of deriving water quality guidelines in Queensland is contained in the DRAFT Guideline Deciding aquatic ecosystem indicators and local water quality guidelines under the Environmental Protection (Water) Policy 2009 (PDF, 1.4MB) , and the Queensland Water Quality Guidelines (see availability).

For more information on the national framework refer to the Australian and New Zealand Guidelines for Fresh and Marine Water Quality.

Water quality guidelines and water quality objectives

Water quality guidelines are often confused with water quality objectives. While guideline values are commonly used as the basis for water quality objectives, conceptually the two are quite distinct.

While guidelines are the technical basis of objectives, final water quality objectives take into account social and economic factors and are ultimately agreed to by all stakeholders. They also usually have some legislative standing whereas guidelines may not. In Queensland, documents containing EVs and the water quality objectives to support them are listed in schedule 1 of the EPP (Water and Wetland Biodiversity). These are available from the department’s web page at Environmental values – Environmental Protection (Water and Wetland Biodiversity) Policy 2019. In areas where no water quality objectives are scheduled, the Queensland water quality guidelines apply as default objectives.

As with guidelines, the term ‘water quality objective’ has traditionally referred only to the physical and chemical characteristics of waters. In modern usage, water quality objectives can encompass a broader range of characteristics including flora and fauna, habitat, flow and physical condition.

Available from the library catalogue

The documents referred to on this page are available from the department’s online library catalogue.