Staff at a New Zealand council have confirmed an old mine shaft is the culprit responsible for turning the Ohinemuri River bright orange.
Waikato Regional Council regional compliance manager Patrick Lynch said the sediment appears to have been shifted from an old mining asset in the hills above the Karangahake Gorge car park, and the flow of water coming from the shaft was now running relatively clear.
However, people are still being advised to avoid touching it as tests to figure out what is in it have yet to be completed.
“The colour indicates it will be iron-related, but it is likely to be highly acidic so again we advise people to treat it as contaminated and not touch it.”
Substances that may be found in old mine assets could include residual arsenic and heavy metals such as cadmium, chromium and antimony, and they could cause risk.
“So avoiding skin contact is the main thing.
“We are testing for these heavy metals, and also mercury, both totals and dissolved.
“We really want to understand how this event happened and that investigation will take time.
“It’s also one of those situations where we are relying on mother nature – a rain event – to wash the contaminant away.
“The more water it’s exposed to, the more diluted it will get.”
The discolouration was reported to the council at about 3pm on Friday, with the council urging people to treat the river as contaminated.
The orange colour appeared to enter the Ohinemuri River downstream of the Waitawheta River, which runs into the Ohinemuri in the Karangahake Gorge.
This article originally appeared on Stuff and is republished here with permission.
