Rivers and reservoirs
The water in streams, rivers, lakes, reservoirs, dams and wetlands is surface water. These systems are replenished by rainfall and by groundwater when it discharges to the surface.
Across South Australia, surface water provides us with drinking water, and water for agriculture and industry, and supports recreation and tourism. Surface water also maintains important cultural sites and a healthy environment.
Many of the surface water resources across the state are prescribed and managed through a water licensing system to make sure water is used sustainably.
To take pressure off our surface water and groundwater systems, including the River Murray, alternative water sources like desalinated seawater, recycled stormwater and wastewater are being used more across the state.
River Murray
Low rainfall means South Australia’s ability to capture water is limited and we rely on the highly-regulated River Murray system for much of our water.
The River Murray provides drinking water for metropolitan Adelaide and many regional towns across South Australia, as well as supports industrial use and irrigation. Water from the River Murray replenishes floodplains, wetlands and ecosystems along the river too.
The Basin Plan sets out how much water can be taken and used from the River Murray. Sustainable limits make sure water is shared between water users and the environment.
Find out more about the River Murray.
Other rivers
- Get to know Adelaide’s River Torrens/Karrawirra Pari
- How to spend a day in Onkaparinga River parks
- Light, Broughton, Wakefield, Willochra, Gawler river catchments
- Glenelg River Estuary
Reservoirs
Reservoirs throughout the Mount Lofty Ranges catchment area are an important source of water for metropolitan Adelaide. As well as storing runoff from the Adelaide Hills, the reservoirs store water pumped from the River Murray to supplement Adelaide’s water supply.
At full capacity, the reservoirs hold about 200,000 megalitres of water (or a little less than one year’s supply for metropolitan Adelaide).
The volume of water stored in the reservoirs relies heavily on rainfall in the Mount Lofty catchment and water pumped from the River Murray.
South Australians in regional areas get their water via one of the large pipelines from the River Murray, from small rural reservoirs or from local dams and groundwater bores.
- Find out about South Australia’s reservoirs - and the Hume and Dartmouth reservoirs in Victoria that play a vital role in maintaining flows to South Australia - at SA Water
Issues for river health
Blackwater
One of the less-welcome side effects of high flows can be blackwater. Blackwater events are a natural phenomenon that occur when areas that don’t see much water are inundated due to the high flows. This stirs up the organic matter like leaves and wood and washes down the river. High levels of organic matter washed into waterways are then consumed and broken down by bacteria. This results in low dissolved oxygen levels, making the water darker in colour and often quite smelly, especially in warm weather. In some instances it can cause distress to fish as well as skin irritations for people who come into contact with the water.
Dissolved oxygen levels in the Murray are typically around 7 mg/L to 11 mg/L. Fish and other aquatic animals may become stressed when oxygen levels drop below 4 mg/L and have difficulty surviving when oxygen levels drop below 2 mg/L. Large-bodied native fish, such as Murray cod, are particularly vulnerable.
Although hypoxic blackwater events may result in the loss of fish and other aquatic life, the impacts of these events on the environment are usually short-term and oxygen levels increase again as the flooding subsides. Blackwater is a temporary event and can eventually result in the increase of food sources for fish from the increased carbon in the water.
Blackwater is acceptable for livestock and animals to drink, but they prefer cleaner water.
- Report large numbers of dead fish or other aquatic animals to the 24-hour FISHWATCH hotline on 1800 065 522.
- Reports of fish kills can also be made through the SA Fishing app.
- Further information about fish kills and how to report is also available on the PIRSA website.
What is blackwater?
Salinity occurs when there is too much salt in the water. Too much salt can affect the quality of the soil, as well as create health problems for the plants and animals that rely on the river for survival.
Increasing salinity levels along the SA River Murray, Lower Lakes and Coorong as a result of drought have negatively impacted on ecosystem health.
High salinity can also reduce irrigated crop yields by reducing plant health and damaging crops. It can make water unfit for consumption by stock, corrode infrastructure and reduce the amount of land available for production. All these impacts adversely affect agricultural industries.
Drinking water supplies can be threatened by high salinity.
Salinity and the River Murray
Salt of the earth
More resources:
Pests and weeds
Not all the plants and animals that live along the river are its friend. There are many pest weeds and animals that can threaten the health of the river and the surrounding areas. Not only that, but they can affect the land of farmers, damaging crops and reducing output.
Work to manage pests includes eradication programs, workshops with landholders to educate on pest management and reporting them to the appropriate authorities.
This video explains how pests are being managed in the Coorong, Lower Lakes and Murray Mouth area:
CLLMM Recovery Project: Pests and weeds
Carp
The overpopulation of carp in Australia has been an ongoing problem for some years. They overwhelm the system and reduce the health of the river as well as the other creatures that inhabit the river.
The Federal Government has been discussing ways to reduce the carp population. They are working on a plan to release a virus into the river that is fatal to carp, but won’t harm the other animals or plants, or affect the water for humans.
The project is still being discussed, as there are many factors to take into consideration, such as how the virus will be distributed, how many carp it will affect, and how to remove the dead carp after the virus has taken effect.
More resources:
