The
Sydney Morning Herald,
6 March 2019:
Residents at Menindee
are bracing for a fourth mass fish kill in the Darling River in about three
months, as a new paper finds water savings in the Murray Darling Basin may be
just one-tenth the amount modelled.
The NSW Department of
Primary Industries has warned the arrival of a cold front after another
heatwave in the region this week posed a "high risk" of another bout
of widespread fish deaths.
Possibly millions of
fish, mostly bony herring but also endangered perch and Murray cod, were killed
in the three previous events. A sudden drop in dissolved oxygen levels - as
blue-green algae died and began decaying - was the prompt for the previous fish
kills.
"They're
super-stressed. It takes less [to kill the fish]," Graeme McCrabb, a
Menindee resident, said on Tuesday. "The numbers of golden and silver
perch and the cods got less [during each die-off]."
Separately, a report
published in the Australasian Journal of Water Resources by John
Williams and Quentin Grafton from the Australian National University found the
$3.5 billion spent on water-saving infrastructure - such as concrete canals -
may have saved 70 billion litres a year compared with the federal government's
estimate of more than 10 times that figure.
Professor Grafton said
their analysis showed the average cost of water recovery could be as much as
$50,000 per megalitre returned to the Murray-Darling Basin every year, or about
25 times more expensive than buying the water back from willing sellers.
The key issue is the
failure to measure and account for so-called return flows - the leakage of
water into aquifer that ceases when irrigation becomes more efficient.
"It's a travesty
for all Australians," he said. "You've spent billions of dollars and
you've not measured what you've got."….
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