Waharoa dairy factory operator Open Country Cheese has been fined more than $11,000 over the illegal dumping of up to 20,000 litres of sludge which contaminated local waterways.

An employee of the company, Allen Pryor, was sentenced to community work for his role in the dumping.

Both OCC and Mr Pryor pleaded guilty to a charge of unlawfully discharging dairy factory wastewater to land where it could enter ground water or a tributary of the Waitoa River.

Environment Waikato had investigated the dumping after a report from a member of the public about "white factory waste" polluting a creek at Waharoa.

The offending early last year came after OCC’s conviction in 2007 for unlawfully discharging wastewater to land.

But, in a Morrinsville District Court decision, Environment Judge Melanie Harland acknowledged new owners who had bought the company in September last year were putting a huge amount of effort into managing environmental issues properly. This had included spending more than $2 million on upgrading OCC’s effluent management system.

"There was a major change in managerial focus to place greater emphasis on management of environmental effects, not only as a compliance matter, but as a goal in itself," Judge Harland said.

"The offending occurred because of poor management practice, which I accept to be historic. The response by OCC to the offending has been impressive. Its response has gone over and above that which might normally have been expected."

David Stagg, EW processing industry manager, said it was disappointing that, under the previous ownership, OCC had under-capitalised and under-resourced its environmental area. The environment including neighbours had been affected and paid the ‘cost’ for this.

However, EW said OCC was doing more under the new owners. "They have made significant improvements on site and in their operations," said Mr Stagg. "We look forward to a good ongoing relationship with the company over the management of its waste."

The court heard how dissolved air flocculator (DAF) sludge from the factory was able to be spread on designated paddocks, as long as certain consent conditions were complied with.

Mr Pryor had admitted he had dumped the sludge in non-permitted areas but said a former director of OCC had told him to put it there.

OCC accepted it had failed to ensure staff disposed of the sludge at permitted locations.

The judge said the sludge was high in nitrogen (its BOD level) and had potential to grow "sewage fungus-type growth" in nearby waterways. BOD levels above four grams per cubic metre of water can kill and stress fish and other aquatic life. The judge said surface water in the Waitoa Stream near one dump site had BOD readings 20 times above the acceptable level.

The court heard from OCC that the negative environmental impacts of the dumping were because sludge had been dumped in localised sites by Mr Pryor rather than being spread properly.

Judge Harland fined OCC $11,050 and gave Mr Pryor 150 hours community work as she was satisfied he could not pay a fine.