The majority of the spilled lactose that entered the Waikato River earlier today has now passed Hamilton City -- and no adverse effects have been found through monitoring.
"The effects of the clean-up operation, combined with a slow travel time of the spilled material through the meandering 12 km of the Mangaone Stream have minimised any adverse effects from the pollution," says Environment Waikato's Group Manager Resource Use, Chris McLay.
"It appears that as the lactose flowed slowly down the Mangaone, it was diluted by fresh oxygenated water flowing into the stream.
"The good news is that our monitoring has shown that the aquatic life in the lower reaches of the Mangaone Stream has not been badly affected.
"While we have seen evidence of eels dying in the upper reaches of the stream, our monitoring today is showing a much better picture for the lower reaches of the stream."
Environment Waikato staff will continue to monitor the Waikato River as far down as Huntly and Tuakau to ensure that no effects are evident further downstream.
Now that the initial clean-up crisis is over, Environment Waikato staff will now turn their attention to investigating the cause of the spill, whereby 500,000 litres of lactose spilled from Civil Whey Distributors Ltd in Hautapu in the early hours of yesterday morning.
"This investigation is likely to take several weeks," says Chris McLay. "After this is completed, we will be in a better position to determine if any enforcement action is warranted."