Moa Point disaster exposes deeper problems, public health experts warn

Public health experts are warning the catastrophic failure of Wellington's Moa Point wastewater treatment plant exposes deep, systemic problems with New Zealand's infrastructure management.

Early last month a blockage in the plant's outfall pipe led to a backflow of sewage into the plant, shutting it down and forcing the closure of beaches along the city's South Coast as up to 70 million litres of untreated sewage was sent into the sea each day.

The University of Otago's Public Health Communication Centre said the failure was a severe example of problems already affecting systems across Aotearoa.

It said Water New Zealand's latest performance review recorded more than 3000 sewage overflows nationwide, though the true number was likely higher because reporting had historically been inconsistent.

It also found about 20 percent of the country's 334 publicly run wastewater treatment plants were operating with expired resource consents, meaning they may not meet current best-practice standards or have robust monitoring in place.

University of Otago research fellow Marnie Pricket said responsibility for water services was spread across multiple organisations, including the national regulator Taumata Arowai, regional councils, local councils and central government ministers.

Pricket said the complexity of that system made accountability unclear when things went wrong.

"For example, Taumata Arowai has oversight of water services but doesn't currently have the legislative tools to intervene if regional councils fail to regulate wastewater discharges effectively."

Poor wastewater management posed risks to both human and environmental health, including exposure to raw sewage, contamination of drinking water sources and polluted shellfish beds, she said.

Ageing infrastructure and climate change were also likely to increase the risk of failures in the future.

The government announced a Crown Review Team would investigate the failure under the Local Government Act 2002. But Prickett said that process appeared to focus largely on the role of Wellington City Council, which could limit its ability to investigate the full range of issues affecting wastewater management across the country.

"The drivers of poor wastewater management are much broader than a single council," she said. "They include policy and investment decisions, workforce limitations, problems with data quality, governance issues, and unclear roles and accountability across agencies."

The upcoming Crown inquiry must examine not just the immediate cause of the breakdown, but the wider drivers behind wastewater failures nationwide, Prickett said.

"If the inquiry is too narrow, we risk learning lessons only about Moa Point," she said.

"But this is a national issue, and the inquiry should help us understand how to improve wastewater management across the country."

The review should follow the model used after the 2016 Havelock North campylobacter outbreak, she said.

"The value of the Havelock North inquiry was that it looked at the specific outbreak, but it also examined the broader drivers of poor drinking water across the country.

"That meant the lessons could be applied nationally. That's what we're hoping for with the Moa Point inquiry."

Local Government Minister Simon Watts was approached for comment.

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