DDT found dumped in South Canterbury river

This was first raised in a TV report in late July -

Residents: Buried DDT contaminating South Island lake

DDT dumped in Opuha River

White granules identified as DDT have been dumped into the Opuha River near Skipton Bridge in South Canterbury.

Contractors and ECan staff remove sediment from the Opuha River at the Skipton Bridge near Fairlie where DDT had been dumped.

Timaru Herald,

14 October, 2015

Environment Canterbury (ECan) staff removed the material with a digger on Wednesday afternoon.

"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," ECan chief executive Bill Bayfield said.

READ MORE:

* South Canterbury Anglers Club raises fresh Opuha DDT claims* Divers take samples after Lake Opuha contamination claims* Renewed allegations of contamination in Opihi catchment

ECan had informed police, the South Canterbury Medical Officer of Health and the Timaru District Council of the discovery.

Buying and using DDT had been illegal in New Zealand since the mid-1970s, and the chemical was the subject of a Government amnesty.

SUPPLIED/ENVIRONMENT CANTERBURY

A map indicating where Environment Canterbury says DDT granules were found dumped in the Opuha River.

Bayfield declined to comment on who might have dumped the granules or why. 

The granules were first noticed in the last week of August by three people collecting sediment samples, following separate allegations of chemical contamination in the catchment.

South Canterbury Anglers Club president Allan Davidson raised concerns about the granules publicly on October 1. At the time, Davidson said Opihi Catchment Environment Protection Society (OCEPS) member Nick Wall told him the granules contained arsenic.

JOHN BISSET/FAIRFAX NZ

A digger removes dumped granules containing arsenic and DDT from the Opuha River at Skipton Bridge.

Davidson was unavailable for comment on Wednesday.

Initial results from testing of the granules, ECan received from University of Canterbury scientists, found evidence of arsenic.

The Timaru District Council had temporarily stopped taking water from the Opihi River until drinking water tests indicated it was safe for drinking.

Preliminary results from sediment sampling, which led to the granules being found, showed "no evidence" of "broad-scale, elevated contamination" in the Opuha catchment's sediment or water, Bayfield said. 

ECan had not yet received DDT results from nine fish it had tested in September.

OCEPS members revealed, in July, test results they claimed showed DDT concentrations well above safe levels. At the time OCEPS spokesman Allan Campbell concluded "there are areas in the bed of Lake Opuha that are contaminated with toxic material".

OCEPS and ECan agreed a joint sampling protocol, leading scientists to take samples from the bottom of the lake and elsewhere in the catchment in August.

ECan had also had a University of Canterbury expert use ground-penetrating radar to test the lake-bed for evidence of buried drums of chemicals while the lake bed was dry during a drought early in 2015.

The tests did not find any indication of buried drums.

Bayfield estimated testing of Lake Opuha for evidence of dumped DDT had directly cost the council between $50,000 and $100,000, but the cost of staff interrupting "existing work programmes" to investigate the claims had also been significant.

He said the costs would be worthwhile when they produced "results that allow people to have faith that there is no broad-scale contamination" from chemicals in the catchment. Bayfield said he would gladly eat fish caught in the lake.

OCEPS members, who were at the river when the granules were removed, were "shocked" by the news, Bayfield said.

He encouraged those with concerns about chemical contamination in the catchment to "read carefully the final report when it comes out".

What is DDT?

Commonly used in pesticides until the 1970s, dichlorodiphenyltrichloroethane (DDT) is a toxic organochlorine chemical which had been inconclusively associated with some cancers.

It does break down easily, and has the potential to "biomagnify" by concentrating in the fat of animals which take it in.