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Coorong, Lower Lakes, and Murray Mouth

Located at the end of the River Murray, the Coorong, Lower Lakes and Murray Mouth (CLLMM) region is one of Australia’s most important wetland areas. The region spans approximately 142,500 hectares and a contains areas of local, national and international importance, as well as one of the most significant waterbird habitats in the Murray-Darling Basin.

The CLLMM region comprises:

Coorong North Lagoon
Coorong South Lagoon
Lake Alexandrina
Lake Albert
Murray Mouth.

Traditional Owners

The Ngarrindjeri and the First Nations of the South East are the Traditional Owners of the CLLMM region, and the health of the River Murray, Coorong and connected lands and waters are central to their culture and beliefs. The Coorong and its connected waters are spiritual waters, as they contain many sacred places of high spiritual significance, providing tangible links to both ancestors and Country.

The wellbeing of Traditional Owners is linked to the health of the region, and they have made significant efforts over many years to be part of managing the region’s environment in response to drought and over-allocation.

Environmental significance

The region’s significance is internationally recognised, with the Coorong and Lakes Alexandrina and Albert Wetland being designated as a Wetland of International Importance under the Ramsar Convention since 1985. The Ramsar site provides significant economic and social value to the region and wider South Australia, supporting a thriving tourism industry, commercial fishing, recreation, Traditional Owner uses and other social activities.

With a unique mix of freshwater, estuarine and marine wetland habitats, the region supports threatened wildlife, rare plants and nationally and internationally significant species such as the Murray hardyhead, fairy tern, southern bell frog, hooded plover, and Australasian bittern.

This mix of aquatic habitats means that the area is rich with many species of fish, with approximately half of all the Murray-Darling Basin’s fish species being found in the region. The area plays and essential role for species that need to move between the fresh, estuarine and marine waters in their lifecycle, including pouched lamprey, common galaxias and congolli.

The region also plays a significant role in supporting waterbirds in the Murray-Darling Basin and forms an important breeding site for many species, including the Australian pelican, straw-necked ibis and Australian fairy terns. The site even supports 37 species of migratory birds that travel from as far as Siberia and Alaska to visit the wetland each year, the importance of which is recognised in numerous international migratory bird agreements.

Due to its location at the end of the River Murray, the Murray Mouth is the only place where salt and other pollutants can be flushed from the Murray-Darling Basin system into the ocean. The region’s health therefore reflects the health of the entire basin and is a good indicator of the Basin Plan's level of success in achieving a sustainable river system.

The region is recognised for its ecological, cultural, economic, and international significance and is now listed as one of The Living Murray’s 6 icon sites. It is also one of 3 priority ecological assets identified in the SA River Murray Water Resource Plan (find it here).

Statement: opening up the Lower Lakes to seawater

Coorong, Lower Lakes, and Murray Mouth — The Coorong is also home to the Coorong National Park.

Ecological site objectives

The region experienced catastrophic ecological decline during the Millennium Drought (1997-2010) from a combination of over-extraction of water and climatic conditions. More than 10 years later, it is slowly recovering with the aid of water for the environment and collaboration between federal and state governments, scientists, First Nations and communities.

What is being done to restore the region’s health

The Living Murray program established 3 high-level ecological objectives to improve the health of each icon site. The objectives for the Lower Lakes, Coorong and Murray Mouth icon site are to achieve a healthier estuarine environment, as indicated by:

an open Murray Mouth
more frequent estuarine fish spawning and recruitment
enhanced migratory waterbird habitat.

Securing the Future: a long-term plan for the Coorong, Lower Lakes and Murray Mouth was developed with input from communities, scientists, industry and government with the aim of maintaining the region as a healthy, productive and resilient wetland system of international importance.

The long-term plan is part of the Government of South Australia's $610 million Murray Futures program, funded by the Australian Government's Water for the Future strategy.

Water for the Coorong, Lower Lakes and Murray Mouth

Murray Mouth

The Murray Mouth, near Goolwa in South Australia, is part of a dynamic system influenced by the flow of River Murray water from Lake Alexandrina via barrage releases and tidal movement from the Southern Ocean.

When the flow to South Australia is low, barrage releases are low and sand deposits occur inside the mouth causing restrictions and increasing the risk of closure. Continuous barrage releases of about 2 GL (2 000 ML) per day are desired to assist in maintaining an open mouth. Much larger volumes are required to provide a scouring effect, removing sand from the mouth.

It is important that the Murray Mouth remains open to maintain connectivity between the river, the Coorong and the Southern Ocean, to discharge salt and other nutrients out to sea, and to maintain healthy ecosystems in the Coorong.

The best way to maintain an open Murray Mouth is through high flows and barrage releases. In the absence of high flows, dredging is considered the most effective method of keeping the mouth open in terms of cost and environmental outcomes, when compared with other intervention methods.

Periods of low flows have presented management challenges in the past. Due to low flows, in 2002 the Murray Mouth threatened to close, and dredging was required for eight years to keep it open. In 2010, the drought was broken with a high flow event and dredging ceased. With the return of low flows, in 2014 the condition and openness of the mouth deteriorated, with dredging recommencing in January 2015. Two dredges are currently operating in the Goolwa and Tauwitchere channels to maintain an open Murray Mouth.

Maintaining an open Murray Mouth is a key objective under the Murray-Daring Basin Plan, which was adopted in 2012. The Basin Plan seeks to ensure that the mouth remains open without the need for dredging 95% of the time under the 3 200 GL water recovery scenario.