1. Water Quality
  2. Introduction to water quality

Introduction to water quality

​​​​Water is one of Australia’s most important natural resources.

Our waterways, including both surface and groundwater systems, catchments, and estuarine and marine water bodies are complex ecological systems that we interact with every day. We rely on these waterways and wetlands for:

  • drinking water supplies
  • irrigation and farming
  • receiving and cleansing effluent and stormwater​
  • recreational and commercial activities like fishing and boating.

Water quality is a critical part of managing water catchments. It affects what we can use the water for and influences the health of the hydrological system. A healthy system will in turn provide better quality water and a more resilient ecosystem.

Maintaining, and where required improving, the quality of waterways means we can continue to access safe drinking water, protect and enjoy our natural environment, and support industries that are dependent on our water resources.

Managing water for both supply and quality can raise some challenging issues. These include variations in:

  • climate
  • topography
  • geology
  • land use.

Readily available information and tools for water managers are essential to improving water quality in Australia.

Issues affecting water quality

Catchment water quality can be influenced by naturally occurring events like droughts, bushfires and floods. The cycle of extreme events is common in Australia, meaning that ecological systems have evolved to cope and sometimes even to depend on these events.

Human activity, including farming and urban development, and a changing climate introduce new environmental stressors. This can make natural events more frequent and the effects more severe.

Harmful impacts to water quality and aquatic ecosystems can also occur as a consequence of cumulative or synergistic effects, which over time can deplete the hydrological system’s resilience and increasing the risk of degradation.​

Awareness of these issues and strategies to manage their effects are an important part of managing water quality.

Issues that can affect water quality include:

  • Acid sulfate soils — soils and sediments with high levels of metal sulfides that can release acid and heavy metals into waterways and wetlands.
  • Blackwater events — where leaf litter and other organic debris is washed into waterways during floods, increasing levels of dissolved organic matter in​ the water column.
  • Cyanobacteria — cyanobacteria (blue-green algae) blooms in still or slow flowing water that pose a risk to our health and agriculture.​
  • Bushfires — loss of soil structure leading to higher levels of pollutants, nutrients and sediments washed into waterways after a fire.
  • Salinity — high levels of naturally-occurring salt in soils or water that can be mobilised by human activity like clearing vegetation or inappropriate irrigation.
  • Urban stormwater — quality of urban stormwater can be affected by contamination from industry and transport, water treatment facilities and residential areas.

Human activity

Our activities can have a significant effect on the quality of our waterways, catchments and estuaries.

Farming and irrigation, mining, and forestry all rely o​n water and all pose risks of returning higher than normal concentrations of chemicals, nutrients or sediments to our waterways.

Urban runoff from expanding cities also poses an increased risk to water quality.

These risks are addressed by regulating the way water is used and managing the effect our activities have on our local waterways.

Managing water quality in Australia

In Australia, water quality is managed through strategies, plans, laws and regulations established by your state, territory or local government. The exception to this is areas such as Commonwealth marine waters.

State, territory and local governments work closely with their communities and industries to provide a water quality management system that protects the environment and balances demands for water.

Some of our most ecologically valuable waterways cross state and territory borders. Good water quality management requires us to work together across all levels of government, and with our industries and communities.

This is achieved through the National Water Quality Management Strategy (NWQMS); a nationally agreed approach to managing water quality.

Resources available through the NWQMS help water managers across Australia to:

  • access best available science to support decision-making
  • adapt guidance to suit local conditions
  • share information across borders and jurisdictions, to reduce duplication
  • work towards a consistent approach without needing national regulatory standards.

State and territory governments work with the Australian government to develop and deliver the NWQMS. While the NWQMS is not mandatory, it is used across all levels of government, and by industry and the general public.

Guidelines for water quality management

Our expectations for the quality of our water depends on the intended use. We might consider the water in a river to be good enough to swim in, but it might not meet drinking water guidelines.

Guidelines for managing water quality help water managers and industry consistently manage their activities and make sure water quality is acceptable for the intended use (fit for purpose).

Providing high quality water, such as drinking water, can be costly and is not always necessary. Some water usage, like for irrigation, can be resourced with water that is lower in quality and cheaper to manage and source.

A focus on fit for purpose means that we are investing the right level of time and money, and using tailored management practices, to achieve water quality that meets the needs of our intended use.

These guidelines address a range of uses for different purposes and water users, setting out good practice for managing water quality in each context.