A Remuera waterway which was polluted by property developers who were fined $67,800 in the Environment Court.

Property developers working in an upmarket Auckland suburb have been collectively fined $67,800 for repeatedly polluting waterways by washing sediment into the stormwater system.

They were working on a property in Spencer Street, Remuera, when they were caught breaching resource consent conditions requiring proper control of sediment works on the site, Auckland council said.

At one stage, a worker was seen sweeping sediment down the footpath into a cesspit.

Cheng Gao, director of Brother Development Limited, pleaded guilty in the Environment Court to multiple charges of discharging sediment and two breaches of abatement notices.

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Han Sun, the son of the Spencer St homeowner, and site manager Jie Ma, pleaded guilty to two charges relating to the discharge of sediment-laden waters at the property, Auckland council said.

Judge Jeff Smith described the offending in his judgment as a "gross violation" of the council's repeated abatement notices ordering them to stop. The offending happened over an extended period through July and October 2018.

When Auckland Council compliance officers learnt of the discharge, they issued an abatement notice and told Ma and Sun they needed to comply with the conditions of consent and the regional rules, including the installation of appropriate sediment controls.

Judge Smith said the developers did take some measures to control the sediment in August or September.

But it didn't last, and Judge Smith told how one worker was told to push sediment along the street to a cesspit, which he described as "a gross violation of the abatement notice".

Auckland Council issued more abatement notices in October but further site visits showed sediment was still not being controlled and was continuing to pollute waterways.

Judge Smith fined and convicted Brother Development Ltd $35,625 for the offending and concluded that as Ma was the day-to-day supervisor of the site, he should have been aware of his obligations to control sediment. He was convicted and fined $21,375. Sun was convicted and fined $10,800.

Auckland Council manager of regulatory compliance Steve Pearce said the fines were a good result.

"Aucklanders want to continue to enjoy their beaches and waterways for many years to come, that's why it's so important our builders and developers are careful with sediment on their sites, and that members of the public are vigilant in reporting anything suspicious to us," he said.

Auckland Mayor Phil Goff added: "It is important that those responsible have received significant fines as a deterrent. Anyone polluting our environment needs to learn that they will be held accountable for their actions."