this might be bad, page-5

Yep looks like its the Talisman mine. Another great excuse for delays ....

https://www.rnz.co.nz/news/national/...orge-the-cause

Seems the council has located the source.

"An old mining shaft has been confirmed as the cause behind turning the Ohinemuri River bright orange yesterday, the Waikato Regional Council says.Regional compliance manager Patrick Lynch said the sediment appeared 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."