A spill of lactose into the Mangaone Stream near Hamilton early yesterday began flowing into the Waikato River early today.
Regional council Environment Waikato this morning said the milk by-product was being diluted to an extent where it was not visible in the river and had not yet caused obvious
problems.
About 500,000 litres of lactose, which came from a ruptured holding tank at Civil Whey Distributors, turned the Mangaone Stream between Hamilton and Cambridge a brownish-white colour yesterday.
The oxygen-sapping substance has already killed some of the stream's aquatic life.
Environment Waikato river and catchment manager Scott Fowlds said no lactose pollution had yet been picked up in monitoring equipment at Hamilton's local water treatment station.
"The lactose entering the river is not expected to pose a major risk, as it is not considered toxic to human health. However, it may have an effect on aquatic life," he said.
Environment Waikato staff would today monitor the river downstream where the pollution entered near Hillcrest.
In addition, monitoring would continue on the Mangaone Stream, where some dead eels have been found.
Council spokesman Ben Dunbar-Smith said investigations were continuing in an effort to establish reasons for the spill.
"It is too early to make any comment about any potential enforcement action at this stage," he said.
As the pollution was travelling slowly, Environment Waikato and Civil Whey Distributors staff had attempted to pump polluted water out of the stream yesterday.
Attempts to stem the flow were more difficult than expected, because of access problems with the steep gully sides along the stream.
- NZPA
