A Waikato resident has pulled out a bucketful of dead eels and kokopu from a stream and says the water has gone pink and opaque.
Eowyn Starr said the creek which ran through her Paeroa property was full of sediment last night and was slowly clearing today.
She first noticed the creek was a pink and white cloudy colour at about midday yesterday and by the evening they were pulling out dead fish.
Ms Starr said nearly 40 dead eels and 14 kokopu had been pulled out, and she had been trying to save several more by putting them in her bathtub and sink.
"It's really alarming, we've only been here a few months and we were really stoked to find that there were kokopu and eels living in our creek.
"It's really gutting to have them all belly up now, I've got a good bucket of dead kokopu and eels all mixed up at the moment, there's a couple of dozen at least."
She was hoping that a concrete mixer she saw parked on the road yesterday was not cleaned out into the creek.
The Waikato Regional Council had staff on their way to investigate the matter.