Soil brought down from nearby developments by heavy rain turned the waters of Nukumea Stream brown, in what residents describe as the worst release of sediment in years. Photo, Bob Rodgers
The once pristine waters of Nukumea Stream flowed brown, carrying a heavy load of silt out to sea at Orewa Beach after recent rain.
The silt came from development upstream – something that Councillor John Watson describes as “environmental vandalism of the worst kind”.
Last year Changda International, developer of Sunny Heights near the stream’s headwaters, was fined $300 by Auckland Council after large amounts of silt entered the stream from its site after heavy rain.
The latest incident, on Saturday April 6, again brought the degradation of local waterways and the marine environment into focus, angering local politicians as well as residents and scientists who have been restoring Nukumea stream.
Chief among their concerns were the effects on 1000 native giant kokopu, which were released into the stream by NIWA last month, as well as likely damage to the stream environment and the shellfish beds off Orewa Beach.
NIWA freshwater ecologist Dr Paul Franklin says giant kokopu tolerate limited exposure to high concentrations of sediment. However, longer-term exposure has an impact and discharges during the spawning season would be a great concern.
Freshwater scientist Sophie Tweddle, of Whitebait Connection, has been working on restoration of the stream for two years. She says sedimentation is a major and ongoing problem.
“I reported a sediment release to Council last week, after heavy rain and heard nothing,” she says. “But this is a whole new level of destruction. I’ve never seen the sediment like this. Planting we did last year is covered. I’m absolutely devastated.”
Council’s regulatory compliance manager, Steve Pearce, says that the Changda development has consent for sediment discharge, however the exceptional amount of rain – 69mm was recorded in Orewa – put substantial pressure on erosion sediment devices.
Council has been on site checking the devices. Water samples were taken for analysis, with results expected in a few weeks.
A Changda spokesperson confirms that the site is being heavily scrutinized and audited by Council fortnightly, as well as after events like the one on April 6, to ensure the company is compliant with its consent conditions.
He says that a silt fence that was breached has been repaired but that also large amounts of sediment wash down from a paper road north of Sunny Heights in heavy rain, which is beyond Changda’s control. “The cut faces on the motorway were all releasing significant sediment into the Nukumea as well,” he says.
Hibiscus & Bays Local Board chair Julia Parfitt and Councillor John Watson received a flood of complaints from residents.
Mrs Parfitt says it is clear that when Council says developments are compliant with sediment control regulations that the standards themselves are not fit for purpose to maintain the health of our streams.
“Nukumea was one of the most pristine streams in Auckland during the Auckland Regional Council days, so it is clear so we need to be better guardians of our waterways,” she says.
Cr John Watson is more forthright, saying that the environment around Nukumea is so valuable that developments causing the runoff should be shut down.
“Perhaps this is the price authorities are willing to pay for development in increasingly marginal locations,” he says. “Higher standards for sediment control need to be introduced with urgency by government at the behest of councils. One problem can be that site sediment erosion control devices function to their design guidelines yet fail to stop incidents like this. To date there has been a bureaucratic reluctance to take this on, despite the fact that some developers have adopted higher and more effective levels of sediment control.”