Waterwatch SA - Saltwatch

Tell me more about salinity

What is salinity

Salinity is an important environmental issue for South Australia. To help you learn more about salinity we have developed two Saltwatch fact sheets:

Salinity Fact Sheet (660KB PDF) - this includes:

What is salinity
How does it occur
The main causes of salinity
The impacts of high salinity
Facts on the how salinity affects Australia
Information on how to measure salinity
Ideas about what you can do to help control salinity.

More Information Fact Sheet (272KB PDF) - this includes:
- Website links for more information on salinity
- Resources to help you learn or teach about salinity

How is salinity measured?

Salinity can be measured in a variety of ways. For the purpose of Saltwatch all groups are encouraged to measure salinity in Electrical Conductivity (EC) units, also known as micro-siemens per centimetre (uS/cm). If your group uses equipment, which measures in another unit then conversions will need to be made.

Electrical conductivity is the property of a substance, which enables it to serve as a channel or medium for electricity. As salty water conducts electricity more readily than pure water, electrical conductivity is a suitable measure of salinity.

How do I convert my salinity readings into EC Units?

To convert readings that are in milli-siemens per centimetre (mS/cm) the reading is multiplied by 1000. For example, a reading of 0.20mS/cm would be 200EC or uS/cm.

To convert readings which may be in parts per million (ppm) or mg/l which is an estimate of the Total Dissolved Solids (TDS) in the solution - a conversion is required. In South Australia, there is a conversion table that is used by Waterwatch programs, which is based upon a conversion factor of 0.56.

To estimate the TDS from the EC reading you need to multiply the reading 0.56. To estimate the EC value from the TDS value you divide by 0.56. For example, an EC reading of 700 would be multiplied by 0.56 to obtain a TDS value of 392 ppm. To convert 392 back to EC units you divide the value by 0.56 to get 700 EC units.

How salty is my region?

Salinity across South Australia is highly variable. Previous Saltwatch data enables us to determine 'normal' or average salinity ranges for each region.

Use Table 1 below to determine the highest and lowest levels of salinity in your region and use Table 2 to determine what the lowest and highest regional salinity values can mean for the plants and animals in that region.

Table 1 - Regional freshwater variations in salinity from Saltwatch data (2001 to 2004)

Region

Salinity Range
mg/l or ppm

Salinity Range
EC uS/cm mS/cm x 1000)

South East

224 mg/l - 11,200 mg/l

400 - 20,000

Broughton Wakefield

100 mg/l - 14,952 mg/l

180 - 26,700

Riverland

100 mg/l - 9520 mg/l

180 - 17,000

Lower Murray

90 mg/l - 11,200 mg/l

160 - 20,000*

Eastern Mt Lofty Ranges

300 mg/l - 10,000 mg/l

533 - 17,857

Onkaparinga

214mg/l - 3192 mg/l

120 - 5700

Patawalonga & Torrens

95 mg/l - 3595 mg/l

170 - 6420*

Northern Adelaide & Barossa

106 mg/l - 7168 mg/l

190 - 12,800

*Some estuarine readings over 30,000 EC recorded for these regions, and for hyper saline environments.

Table 2 - What does your salinity level mean?

Range mg/l or ppm

Range EC uS/cm (mS/cm x 1000)

Score

Explanation

approx.
0 - 480

0 - 800

Very Low for SA freshwater sites

Range for rainwater and tap water. Good drinking water for people and suitable for animals and plants.

approx. 480 - 1500

801 - 2500

Low to Medium salinity level, for most flowing freshwater environments in SA

A healthy level for most aquatic invertebrates and plants. People can drink water in this range, but it would start to taste very salty. Some plants such as peas, apricots and grapes cannot be grown with water over 1500uS/cm

approx. 1500 - 6000

2500 - 10,000

Medium to High salinity level for freshwater sites in SA, depending on location of site.

approx. 6000 - 28,000

10,000 - 50,000

High to Very High salinity level for freshwater sites in SA, depending on location of site.

Most freshwater animals and plants will die. Not suitable for poultry, pigs or lactating animals, but beef cattle can use water up to 17,000uS/cm, and adult sheep on dry feed can tolerate up to 23,000uS/cm. Sea water is 50,000uS/cm. Some specialised aquatic species can tolerate high salinity levels, e.g. in estuarine environments.

approx. 28,000 - 42,000

50,000 - 70,000

Extreme salinity levels

Same as seawater or hyper saline. Some specialised aquatic species and marine species can tolerate such extreme salinity levels.

Key Facts on Salinity & Water Quality

The 2003 State of the Environment Report indicates a number of key findings in relation to salinity and water quality in SA.

The findings indicate:

Water quality in rivers and streams of the Mt Lofty Ranges is moderate to poor with no significant change since the 1998 State of the Environment Report.
Groundwater quality is declining and in some regions the single biggest threat to groundwater quality across the state is salinity
Salinity levels were poor to moderate in the North Para and Bremer rivers, particularly for drinking and irrigation purposes. Levels were good in the Myponga River and First Creek.

View the full 2003 State of the Environment Report.

Links

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