Managing salinity in the Lower Lakes and Coorong
At a glance
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Low flows can allow salt from the
entire Murray-Darling system to
build up in the Lower Lakes instead
of flushing out to sea through the
Murray Mouth.
In some areas water is too salty for
drinking, livestock or irrigation.
If salinity is too high, freshwater
plants and animals cannot survive.
The Lower Lakes have mostly been
fresh water for the last 7000 years.
The recent increase in flows has
allowed salt to be flushed out to
the Coorong and Murray Mouth.
More freshwater flows and keeping
the Murray Mouth open are key to
managing salinity in the region.
What is salinity?
Salinity is the amount of salt in the water.
Higher salinity means more dissolved salts.
Electrical Conductivity (EC) is used to
measure salinity. Dissolved salt carries an
electrical current, so the more salt in the
soil or water, the higher the EC units will be.
Why salinity has increased
Salt from the entire Murray-Darling system
is naturally washed out to sea through the
Murray Mouth.
However, with less water flowing down
the River Murray, only a very small amount
of water flowed out to the sea between
November 2005 and late 2010. This
resulted in a build up of salt and nutrients
in the Lower Lakes.
High evaporation due to above average
temperatures has also increased salinity in
the region.
How salty is the water?
There are 23 different wetland types in the
Coorong, Lower Lakes and Murray Mouth
region, ranging from fresh water to
estuarine to saline, with hyper-saline
wetlands now present in some parts of the
Coorong’s South Lagoon.
Fresh water history of the Lower Lakes
The Lower Lakes have predominantly
contained fresh water for 7000 years, only
occasionally becoming a more estuarine
environment for a short period of time.
Therefore rising salinity is having a serious
impact on plants and animals in the lakes.
Problems caused by high salt levels
Taking action to reduce salinity
Salinity is increasing across the region, and
in some areas salt levels are now too high
for the once fresh water to be used for
drinking, livestock, or even irrigation.
The South Australian Government has
taken a number of actions, including:
This is having an impact on the region’s
economy, particularly the agricultural
industry.
The Lower Lakes region is internationally
recognised as a ‘Ramsar Wetland of
International Importance’ because of its
diverse habitats, plants, and animals.
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Rising salinity is affecting the range of
plants and animals that can survive in the
region and, at high enough levels, could
cause many freshwater species to die.
Plants and animals that normally live in
the sea can also cause problems for
freshwater animals. An example of this is
tubeworms in the Goolwa Channel and
some areas of the Lower Lakes.
Monitoring water quality
Water quality monitoring is regularly
carried out across the Lower Lakes,
Goolwa Channel, Currency Creek, Finniss
River, and Coorong.
The results of this monitoring show
changes in salinity and are used to
decide if action needs to be taken to
help the environment, and what the best
action would be.
The Environmental Protection Authority,
South Australian Murray–Darling Basin
Natural Resources Management Board,
Department for Water, and local
community groups are all involved in
water quality monitoring.
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dredging to keep the Murray
Mouth open
sealing the barrages to keep sea
water out of the Lower Lakes
recycling waste water and re-using
storm water to reduce reliance on
the River Murray
buying water on the temporary
water market to provide fresh
water to the Lower Lakes
captive breeding programs for
native fish, to be reintroduced
when salinity levels return to a
tolerable level
building Adelaide’s desalination
plant to reduce reliance on the
River Murray
flushing salt from the Lower Lakes
through the barrage network.
Why managing salinity is difficult
The best way to manage increasing
salinity is to flush the system with fresh
water. During times of drought and low
river flows this is difficult. Therefore it is part
of longer-term plans to manage the issue
as regular fresh water flows return.
Further information
Department for Water
www.waterforgood.sa.gov.au
SA Environment Protection Authority
www.epa.sa.gov.au/water_quality
Department of Environment and Natural
Resources
www.environment.gov.au/cllmm
River Murray Data
data.rivermurray.sa.gov.au