Mine's toxic flow gives river users a scare.

Macleay River ... dead catfish, shellfish and bass. Photo: Jenny Evans

A PLUME of toxic pollution from an old antimony mine appears to have killed fish for dozens of kilometres along the Macleay River in northern NSW. The state government said there was no increased health risk because the contamination from the Hillgrove mine, east of Armidale, was diluted, but it has been ringing residents along the river as a precaution to tell them not to drink the water.

People living near the river and a tributary called Bakers Creek have found dead catfish, bass and shellfish, following recent heavy rain that caused a storage pond at the mine to overflow.  An investigation by the Environment Protection Authority began in August, and it estimates 900,000 litres of contaminated water entered the river when the storage pond overflowed.

''These overflows have been significantly diluted by rainfall runoff into the dam and from runoff into the creek from the catchment,'' the Environment Minister, Robyn Parker, said in a statement.
''The result of this rainfall is a significant dilution effect with no resultant change to background contaminant levels … water quality has not been impacted.''  But a study published by the CSIRO in 2009 described the waterways near the mothballed mine as ''highly contaminated'' and estimated about 7000 tonnes of waste had accumulated along the bed of the Macleay River.

Water tests have shown antimony levels at 250 times background levels, with high levels detected along the river to the coast at Urunga, where the mineral was once processed for export. 

Antimony, a silver-grey metal used in fire retardants, lead-acid batteries and electronic devices, is potentially fatal if ingested, and even small doses can cause headaches and dizziness. High levels of arsenic were also detected.

''This government is rapidly developing an abysmal record in environmental management,'' said the NSW Greens MP Jeremy Buckingham, who recently visited the area around the mine.  He wants a government investigation into health effects and potential loss of income for fishing and tourism operators along the length of the river.  Ms Parker said advice not to pump water from the river was ''standard advice and remains in force at all times''.

The company that owns the mine, Straits Resources, has been trying to minimise the pollution.  'They recently installed a much larger evaporator. In addition, they have been undertaking drainage work to direct stormwater away from the ponds in a bid to minimise inflows,'' Ms Parker said.

The Hillgrove mine may soon be reopened after it was purchased by Ancoa NL. Gold and antimony have been mined in the area since the 1880s.

Read more: Sydney Morning Herald