| Coorong and Lower Lakes and the Murray Mouth |  |
What is important about the Coorong?
The Coorong is ecologically and culturally very important. The Coorong is a unique ecosystem and estuary with significant conservation value for its biodiversity. Most significantly, it was declared a Wetland of International Importance in 1985 under the Ramsar Convention.
The Coorong provides a mosaic of habitats for birdlife. Thirty-three of the eighty-five species of bird found at the Coorong are listed under international treaties.
The Australian Government, in recognising the importance of the Coorong for migratory birds, has established agreements with the Governments of Japan and
The Peoples Republic of China to protect the habitats of migratory birds.
Additionally, Australia is a member of the East Asian-Australasian Shorebird Reserve Network, which seeks to conserve key wetlands – such as the Coorong - in the migration route flyway.
Such is the Coorong’s importance in providing valuable habitat for migratory birds; some species will migrate from as far away as Siberia and Alaska to the Coorong.
The Coorong also provides irreplaceable habitat for 14 threatened species of bird, and an important drought refuge in the area. It is also supports the worlds largest breeding colony of Australian Pelicans.
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Where does the Coorong start and finish?
The Coorong starts at the mouth of the Murray River, south east of Goolwa. It extends for 140km along the coast in a southeasterly direction towards the town of Kingston.
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How has the Coorong changed?
Since European settlement, river regulation within the Murray-Darling Basin has caused a quite dramatic change to the Coorong.
Being at the end of the Murray-Darling Basin, the Coorong receives, directly or indirectly, the impact of actions and decisions made throughout the basin.
There are now over 100 regulatory devices in the Murray-Darling system, including five barrages, which separate salt and fresh water close to the river mouth.
Land clearance, soil salinisation, erosion and polluted drainage into rivers have changed the water quality of the Murray-Darling system.
The abstraction of water for irrigation has altered the flow regime, resulting in a much-reduced overall flow, and diminished flooding events.
Consequently, the river system is now a steadier one. Simple habitats have replaced once complex ones, resulting in less habitat types and thus fewer species.
Reduced flows have resulted in long periods of time when no fresh water reaches the Coorong via the barrages. This causes a change in the salinity levels of the estuary, deprives it of nutrients and allows sand to accumulate inside the river mouth.
Consequently, many estuarine species, (species found at the Murray Mouth) which relied on variable, brackish conditions, are being replaced with marine species.
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What are the Lower Lakes used for?
The Lower Lakes constitute the largest freshwater body in South Australia. They provide permanent and ephemeral, highly productive wetland ecosystems and highly important habitat.
The Lower Lakes are fringed with tall weeds which provide unbroken habitat which fulfils a critical role in allowing birds safe movement, reducing the risk posed by predators. Additionally, the Lower Lakes are used to store water for irrigation and some town water.
The Lower Lakes region is growing as a tourist destination and this is reflected by the, at times, heavy use for recreational pursuits, such as boating activities and fishing.
The Lower Lakes are used for irrigation and extensive recreation these days. However, in the mid-late 1800s and early 1900s the River and Lower Lakes formed an important part of the commercial River transport system.
The town of Goolwa, located on the north-western side of Lake Alexandrina at the end of the River system, was an important river trade port.
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Why don’t they stop the evaporation from the Lower Lakes so we have more water?
Unfortunately, there is nowhere to store the water, therefore savings can’t be made.
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Why does the Murray Mouth closed?
Sand accumulation in the area of the mouth has been more prevalent since the construction of the barrages in the 1940s. This essentially reduced the tidal prism by reducing the area of water that would have once been open to tidal influence. The tidal prism describes the balance between the incoming and outgoing tides.
The incoming tides in the Mouth region are significantly stronger than the outgoing tides resulting in a net accumulation of sand.
Additional factors influencing the increased deposition in the area include further upstream development which occurred particularly throughout the 1980s, coupled with prevailing long term dry weather conditions which appear to have had an effect on flows to South Australia.
The reduced flows have also reduced the capacity of the Mouth to be cleared. Tidal action alone is not enough to maintain an un-congested mouth.
Subsequently, the accumulation of sand at the mouth has become a significant ongoing problem over the last 20 years.
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Why don’t they just dig out the sand in the Murray Mouth to open it wider?
Easier said than done. Firstly, a significant sized dredge would be required for such a large scale operation and there are many issues regarding the transport of such equipment into the area given its shallow nature and strong surf among other conditions.
Secondly, cost is a significant factor and has proven somewhat prohibitive for the time being. Rough estimates suggested are upwards of 10million dollars. In the meantime, if the mouth can be moderately maintained in the interim awaiting a change in the long term weather pattern for wetter conditions, nature will improve the situation at the mouth far better than we possibly could.
In the meantime, the best strategy for the mouth is to keep close watch to ensure that the local ecosystem is not under serious threat when difficult conditions are prevalent. Management actions are engaged as precautions and when necessary.
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What are the barrages?
The barrages form a barrier between the fresh waters maintained in the Lower Lakes and the hyper-saline environment of the Coorong estuary and the Southern ocean.
Essentially, the barrages are like dams or weirs in that water can be manipulated from them. Although the barrages differ from dams or weirs because the barrages extend over a much greater distance and not to any great depth.
There are five barrages (Goolwa, Boundary Creek, Mundoo, Ewe Island and Tauwitchere) each of differing lengths. However, combined they cover a length of almost 8 kms.
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What is Ramsar?
Ramsar is the name of a town in Iran. Delegates from 18 countries and observers from a number of other countries met in Ramsar because of concerns at the worldwide loss of waterbirds and their wetland habitats. The result was the first international nature conservation treaty.
This was called the Convention on Wetlands of International Importance Especially as Waterfowl Habitat. This is commonly known as the Ramsar Convention.
Australia was the first signatory to the Convention in December 1975.
Each signatory country – of which there are now 123 – is obligated to designate at least one wetland for inclusion in The List of Wetlands of International Importance.
The Coorong, pursuant to Australia’s obligations under the Ramsar Convention, is subject to a management plan which provides a framework for its conservation and wise use.
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What is the Ramsar Convention?
The Convention on Wetlands, signed in Ramsar, Iran, in 1971, is an intergovernmental treaty which provides the framework for national action and international cooperation for the conservation and wise use of wetlands and their resources.
The Ramsar Convention covers all aspects of wetland conservation and wise use, recognising wetlands as ecosystems that are extremely important for biodiversity conservation and the well-being of human communities, as well as waterbird habitats.
Australia was the first signatory to the Convention in 1975.
There are presently 123 Contracting Parties to the Convention, with 1050 wetland sites, totalling 78.7 million hectares, designated for inclusion in the Ramsar List of Wetlands of International Importance.
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What sorts of birds use the Coorong?
Eighty-five species of bird have been recorded at the Coorong. Additionally, the region is regarded as a major site in South Australia for more than 30 species of waterbirds.
The region is important for migratory waders, principally Red-necked Stints, Sharp-tailed Sandpipers and Curlew Sandpipers. The Coorong is an important habitat on their migratory flyway between Australia and their northern breeding grounds. These species, among other waders, are also protected under the Japanese-Australia Migratory Bird Agreement (JAMBA) and the China-Australia Migratory Bird Agreement (CAMBA).Resident waders such as stilts, avocets, plovers, lapwings and oystercatchers are present at the Coorong. There are many species of duck that use the Coorong.
Other birds in the area include Ducks, Black Swans, Pelicans, Ibis, the rare Fairy Tern and the endangered Little Tern. At times, the numbers of Grey Teal can be in excess of 50 000. Australian Shelducks also occur in large numbers. In drought years, up to several hundred thousand ducks use the Coorong.
There are also about 2000 Cape Barren Geese during the summer months. Pelicans, ibis and swans all use the Coorong to breed.
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How salty is the Coorong? Will this affect the birds and fish?
The salinity levels of the Coorong vary between different areas and within different seasons.
On average, the Southern Lagoon of the Coorong is nearly twice as saline as the Northern Lagoon.
Coorong habitats range from seasonally fresh near the barrages when large quantities of water are being released, to brackish in the Murray Mouth area, grading to hypersaline in the Southern Lagoon. The salinity level of the Southern Lagoon is 140 parts per thousand (ppt), the Northern Lagoon is 80ppt – far greater than South Australia seawater which is only 35ppt.
Most species of birds and fish have a definite range of salinity in which they can survive. The fluctuations in the salinity levels of the Coorong favours some species, whilst disadvantaging others.
Some estuarine species of birds and fish that rely on the high productivity of a variable, mostly brackish water ecosystem are replaced by marine species, which can tolerate higher salinity levels. The lower productivity of higher salinity levels supports fewer numbers of waders and other estuarine water birds, which must either find resources elsewhere or die out.
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What is being done?
A number of projects are currently underway for the Murray Mouth, Lower Lakes and Coorong region and of these projects some are acting on recommendations of past reports for the first time.
The reason for this is that much of the technology required to pursue these endeavors has not been available or sophisticated enough to justify their pursuit. However, this has been changing rapidly in recent years. Hopefully, in the not too distant future we will have a far better understanding of this dynamic region and how to manage it.
Government of South Australia
The Government of South Australia released the Coorong, and Lakes Alexandrina and Albert Ramsar Management Plan. The vision contained in the plan is to enable the continued wise use of the area.
The vision is to:
- Conserve the environmental and ecological attributes
- Use the natural resources in a sustainable manner
- Protect and restore natural habitats
- Restore viable populations of viable species
- Increase community commitment and awareness, including the Ngarrindjeri
people
- Improve water quality and increase flows through the wetlands
- Fulfil Australia’s obligations under the Ramsar Convention and other
international agreements
A Task Force will be established to drive the implementation of the Plan. As part of the implementation, the Coorong National Park is being extended to include the waters of the northern Coorong and estuary up to the Goolwa barrages.
There are many groups actively improving the Coorong and Lower Lakes wetlands, including the Goolwa to Wellington LAP, Landcare groups, community groups, indigenous groups, and local government.
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What can I do?
Join community volunteer groups, such as Friends of the Coorong, which work to conserve the Coorong and Lower Lakes area, or local Landcare groups.
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Information
Information sheets
Murray-Darling Association
What’s What about Lower Lakes of the River Murray, Fact Sheet 13, 1997 (also on website at www.murrayusers.sa.gov.au)
The Lower Lakes and Coorong Region, Murray Mysteries information sheet, 1998.
The Lower Murray: Morgan to the Mouth, Information Sheet, MDBC.
Birds of the Lower Murray and Coorong, Murray Mysteries, 1998. <...Back to Top...>
Contacts
Coorong / Lower Lakes / Murray Mouth Contacts
- Department of Water Land and Biodiversity Conservation, Murray-Darling
Division
- RAMSAR see Department for the Environment and Heritage
- Coorong National Parks and Wildlife SA
- Coorong District Local Action Planning
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