Waikato Regional Council’s investigation into the discharge of orange sediment into the Ōhinemuri River last month is in its final stages, with “no clear evidence of culpability other than it being the result of mining activities more than 100 years ago”.
It comes nearly two weeks after the council confirmed it had results from testing for all 30 heavy metals, plus cyanide, following a bright orange sediment discharge from an historic mine shaft into the Ōhinemuri River on August 23.
On Tuesday, the council said a solid sediment sample taken from the stream bank and from the mine outlet showed very high arsenic levels that would pose a human health risk if ingested.
Council regional compliance manager Patrick Lynch said sediment was still in the Nohopane Stream and had settled along parts of the Ōhinemuri River. He urged people to avoid contact with the sediment, which was bright orange in colour due to high iron content.