Test results show faecal contamination levels were 100 times the normal range at least eight hours after untreated effluent flowed from a Te Kuiti meat works into the Mangaokewa Stream, the source of the town’s water supply.
Waikato District Health Board issued a warning on Saturday to Te Kuiti residents to boil water before drinking or brushing their teeth and not to swim in the stream.
Medical Officer of Health Dr Dell Hood said these warnings would stay in place until further notice.
Environment Waikato water quality scientist Bill Vant said the regional council’s testing indicated the stream had been highly contaminated.
“We won’t know if the stream is clear for some days as it is possible highly contaminated water is still moving through the ground into the stream,” he said.
Resource Use group manager Chris McLay said Environment Waikato staff were investigating the incident, which occurred between 9pm Friday and 7am Saturday when the spill was discovered.
“Our staff will continue to investigate the circumstances that led to the discharge to determine the causes of the incident and whether any liability exists,” he said.
Initial reports say the earth walls of the meat works’ effluent holding pond cracked, spilling up to three million litres of effluent from the pond into a tomo. The tomo overflowed into a stormwater drain which discharges into the stream. At this stage it is estimated some 500,000 litres of effluent contaminated the waterway.
As soon as Environment Waikato was alerted at 10.30am on Saturday, the regional council’s ready response team went to the site, with its first priority being to contain the spill.
At this stage there have been no reports of harm caused to aquatic life in the stream.
The Mangaokewa Stream is a tributary of the Waipa River which meets the Waikato River at Ngaruawahia.
Down stream users of water from the stream include neighbouring town Otorohanga, which has been notified of the potential for increased faecal counts.
Environment Waikato staff – including engineers experienced in land stability issues – are working with the meat processing company to try to minimise the risk of further land movements at the site.
Regional council staff will continue the water sampling regime to assess the spill's impacts.
It will also be closely monitoring the effects of heavy rain forecast this week. The rain could dilute the contamination, but could potentially cause further destabilisation of the ground.