‘It’s not actually the farmers’
Farmers and developers deny contaminating the Kaipara Harbour and so does Watercare.
Helensville resident Bonnye Johnson’s family had five generations of fishermen who fished the Kaipara Harbour. She claimed harbour contamination was caused by the Helensville Wastewater Treatment Plant.
‘‘Everyone blames the farmers. And it’s not actually the farmers,’’ she said.
Johnson said the smell coming from the wastewater system was ‘‘putrid’’ and she had seen ‘‘black streak about 12-foot wide’’ coming out of the sewerage gates.
But Watercare spokesperson Brent Evans denied the wastewater system was contaminating the harbour and said no sludge was discharged into the river or harbour.
He said the plant followed resource consent conditions including the discharge volume not exceeding 5,500 cubic metres per day. Watercare was granted resource consent in April 2012 to upgrade the 4.1 hectare plant on the Kaipara Coast Highway. The plant discharged into the Kaipara River, which flowed into the harbour.
The consent said the upgrade would result in ‘‘substantial decreases in biochemical oxygen demand being discharged to the Kaipara River’’.
Evans said Watercare had progressively upgraded the plant including a new inlet screen, biofilter and caged-brush aerators had been installed and the outfall pipe that discharged treated wastewater had been replaced. The upgrade was completed in September 2015. Where he had not researched wastewater contamination in the Kaipara Harbour, Niwa marine ecologist Dr Mark Morrison said it was especially under stress from sedimentation and water quality. He said visibility was degrading, making it harder for plants that snapper used for shelter to grow.
Treatment plants that purify water to a high standard can minimise the risks of harm to waterways, Niwa’s website said. It also said treatment plants can significantly impact the environment and fish.
Evans said the wastewater from the treatment plant was treated to a ‘‘very high standard’’ and underwent more scrutiny than other activities around the harbour. The plant discharged ‘‘tiny’’ volumes of wastewater into the Kaipara Harbour when compared to other Watercare plants.
Sediment plume dispersing into the Kaipara Harbour from the Hoteo River.