pH (changed from natural)

The pH of water relates to how acidic (pH <7) or alkaline (pH >7) the water body is. pH can be altered by industrial discharges, fertilisers, detergents, insecticides and run-off from Acid Sulphate Soils. Changes in pH affect the form and activity of many chemicals, making them more or less harmful to organisms depending on the chemical type and the nature of the pH change.

View a conceptual model of potential causes of a change to pH and the condition responses observed as a result of this change.


 Potential indicators

There are a number of causes and symptoms related to this stressor. The following indicators are recommended for the stressor ‘pH’:

Pressure indicators

Indicators of pH sources:

  • Percentage of estuary adjoining disturbed acid sulphate soils

Indicators of direct pressure:

  • None

Vulnerability indicators

Condition indicators

Physical-chemical condition indicators:

  • Minimum sustained pH values during the days following an inflow event
  • Ambient pH

Biological condition indicators:

  • Number of mass mortality events caused by low pH
  • Red-spot disease of fish
Possible causes Possible symptoms
The actions/events/situations that might induce this stress: The actions/events/situations that might arise from a change to the stressor:

Background science


Other information on altered pH


Global Environment Monitoring System (GEMStat) is designed to share surface and ground water quality data sets collected from the GEMS/Water Global Network, including over 1,400 stations, two million records, and over 100 parameters.


Australian Natural Resources Atlas. One of the key information delivery mechanisms for the National Land and Water Resources Audit. Search the Australian Natural Resource Atlas for information about surface water quality monitoring programs in Australia.

Australian Natural Resources Data Library. You can search for metadata (data about data) here.

Interactive maps. The National Land and Water Resources Audit compiled information on pH as part of its condition assessment of Australian estuaries.

ACT Waterwatch.The Waterwatch database program allows you to enter your Waterwatch data and store it as a record or file; develop graphs and produce short reports about your data; and perform simple analyses on the Waterwatch data you have collected from your catchment. It can be downloaded from this site.

New South Wales

Acid Sulfate Soils Risk (NSW). This project has mapped the occurrence of Acid Sulfate Soils (ASS) along the coast of NSW and provides information that will assist land management and rehabilitation.

Australian Natural Resources Atlas. Data were primarily provided by the Department of Land and Water Conservation’s Key Sites Surface Water Quality Program. Click on the basin name in the table to view a water quality report for that basin.

NSW Natural Resource Atlas. The Natural Resource Atlas is the New South Wales portal to maps and data for environmental management, planning, research and education.

Distribution of Acid Sulphate soils in NSW

Lake Macquarie Acid Sulphate Soils. Maps can be downloaded from this site.

Streamwatch – Australian Museum. This site has water quality data available from different regions throughout New South Wales are available for most Streamwatch sites.

Waterwatch NSW. Choose a Waterwatch site from an interactive map of New South Wales. Water quality data are available for most Waterwatch sites.


Acid Sulphate Soils – QASSIT Maps. Information on prices of these maps and how to obtain them.

Australian Coastal Atlas. The QEPA’s water quality data is now available on the internet via the Australian Coastal Atlas (ACA). The ACA allows maps to be produced from a number of available data layers. Water quality monitoring sites can be presented on a map and viewed at a number of different scales alongside other datasets.

Australian Natural Resources Atlas (Qld). 262 sites, (163 DNR & 99 EPA) were reported covering 34 basins. Click on the basin name in the table to view a water quality report for that basin. Data includes turbidity.

Coastal Habitat Resources Information System (CHRIS). Interactive maps showing coastal habitats, with options for showing water quality monitoring data, including pH.

Department of Natural Resources and Mines. Data on the ambient quantity and quality of the State’s freshwater resources in streams and aquifers is available to the public in digital format under a range of fee and access arrangements.

Watershed. This web site provides access to gauging station information, streamflow data summaries and chemical analyses of water samples from the surface water data archive.

Waterwatch Gold Coast. This site provides some water quality data from the Waterwatch program, including pH values from a number of creeks in the Gold Coast Region.

South Australia

Australian Natural Resources Atlas. The Department of Environment, Heritage and Aboriginal Affairs (DEHAA) and the South Australian Environment Protection Authority (EPA) are involved with this monitoring program. Click on the basin name in the table to view a water quality report for that basin.


Australian Natural Resources Atlas. Victorian Department of Natural Resources and Environment (DNRE), Environment Protection Agency (EPA) and Melbourne Water are involved with this water quality monitoring program. Click on the basin name in the table to view a water quality report for that basin.

Catchment Indicators Online Provides current information about the management and changing condition of Victoria’s land and water resources.

Water Measurement Information System. This site combines data from a number of community and scientific based monitoring programs into one easily accessible resource.

Western Australia

State-wide assessment of river water quality. Click on a drainage basin to access water quality data. Data is presented on maps and include values for pH where available (for years 2000-2003).