Ecan call police over alleged dumping of arsenic and DDT at Opuha Dam

See also: Ecan's democracy-limiting Bill introduced by Smith

Environment Canterbury says it has contacted police about DDT and arsenic it believes were dumped at a weir below the Opuha Dam in south Canterbury.

Chief executive Bill Bayfield says no evidence of elevated pesticide contamination has been found in sediment under Lake Opuha or at the weir below the dam as a result of sediment sample tests carried out by three accredited laboratories in the past month.

A group called Opihi Catchment Environment Protection Society raised the alert three years ago as a result of information it had received that someone had been seen burying drums of pesticide in the lake bed when it was being prepared in 1998.

But a survey has found that a small area of sediment containing white granules has been deposited into a small area of the Opuha River near Skipton Bridge in recent months, Mr Bayfield says.

Test results show it has very high levels of DDT and arsenic, and the deposits are “fairly new”.

“The only conclusion we can draw is that someone has, in the last couple of months, deposited what farmers would recognise as prills of DDT and arsenic into a very small area of the Opuha River, near Skipton Bridge. If this is the case it is a despicable action.”

Environment Canterbury has discussed the issue with the police, and has notified the South Canterbury Medical Officer of Health and the Timaru District Council.

The small area of sediment containing these white granules has been removed from the river bed near Skipton Bridge.

“We cannot ignore the evidence, that apparently someone has put the DDT and arsenic granules into the Opuha River and has potentially endangered the health of the people and animals that use that water. The contamination must be removed.

“We will complete further tests on the sediment at this location in coming weeks after the clean-up is completed,” Mr Bayfield says.

“As far as we are concerned we have found nothing to support claims that drums of pesticides were buried under the lake bed before it was filled in 1998. There is no evidence of a dump, and no evidence of subsequent contamination in the lake or the river.”

“While we will always have the door open to further evidence, perhaps when the lake is empty again, we hope that this is the end to speculation and provides certainty for Opuha Water users.

 “All our tests, from 2011 and again in 2015, show the water, the lake bed, the river water and sediment are at or below safe expected levels.

 “We have worked closely with OCEPS. We took its claims of contamination seriously. We have spent a considerable amount of time and money conducting tests to its satisfaction,” Mr Bayfield says.

Test results to date:

*2011 -  Lake-water, downstream river water, fish and eels from the lake showed no pesticides (DDT/DDE) above the safe expected levels for Canterbury. Ground penetrating radar of the lake bed in areas allegedly contaminated showed no evidence of bed disturbance or containers.

*April – July 2015: Test results provided by OCEPS from samples taken by it from the lake bed and downstream in April showed very high levels of DDT/DDE in four of the samples.

*In April 2015, when dry weather exposed much of the lake bed, a further ground penetrating radar test was conducted of the lake bed by a University of Canterbury scientist proposed by OCEPS and no evidence of bed disturbance or buried drums was found.

*August-October 2015: Lake-water, downstream river water and fish from the lake and downstream at the sites located by the eight GPS co-ordinates provided by OCEPS showed no pesticides or arsenic above the safe expected levels for Canterbury. These test results came from three accredited laboratories – Hill Laboratories (Hamilton), ALS Laboratories (Sydney) and Asure Quality NZ. Fish from the lake provided by Fish and Game are still being analysed. 

c.hutch@clear.net.nz

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