WA: Salt added to Swan in bid to control algal bloom

AAP General News (Australia)
02-15-2000
WA: Salt added to Swan in bid to control algal bloom

PERTH, Feb 15 AAP - Eleven tonnes of salt were added to a section of the Swan River
today in a bid to contain a highly-toxic algal bloom which has closed the river and parts
of its tributary, the Canning.

Authorities are struggling to control the disastrous blue-green algae bloom along the
length of the Swan, among the worst found in Australia.

Yesterday they sprayed sea water into the areas of the river with the highest concentration
of the algae.

The algae survives only in fresh water and scientists had hoped adding seawater would
raise the salinity levels enough to eliminate some of the bloom.

But the seawater's salinity was not high enough to make a difference, Swan River Trust
river manager Daryl Miller said today.

Mr Miller said a family-owned salt company donated 11 tonnes of salt, which would be
made into a strong brine solution and sprayed into Claisebrook Cove at East Perth today.

"This will bring the salinity in the cove up to something like (that of) sea water
and just deal with the concentrations of the algae in the cove."

The outbreak last Friday prompted health authorities to warn the public not to engage
in any recreational activity on the river.

The warning initially was confined to the 10km city reach of the river but extended
at the weekend to the entire 40km length of the popular waterway.

Yesterday, authorities added the mouth of the Canning River.

Mr Miller said the Swan River Trust would trial adding a common clay to the worst areas
of the river tomorrow.

In laboratory tests yesterday, the algae had stuck to the clay, forming dense clusters
and sunk to the bottom of vials.

If successful on the river, the algae would drop to the river floor where it would
be starved of light and die.

Meanwhile, skimming operations would continue.

The algal bloom was caused by a combination of recent heavy rains and high temperatures.

The salt donated for the algal-control efforts had a commercial value of $1,800.

Water Resources Minister Kim Hames said today the government had not considered financial
help for businesses affected by the river closure, including commercial fishermen and
boat hire operators.

AAP sd/ah/br

KEYWORD: SWAN NIGHTLEAD

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