Moa Point waste water treatment plant in Wellington. Photo: RNZ / Angus Dreaver
A freshwater scientist is adamant slated changes to the rules around releasing treated sewage into waterways is a backwards step, but the regulator says it will bring much-needed consistency to wastewater treatment.
The water regulator, Taumata Arowai, plans to introduce new 'national standards' for the amount of pollutants, such as E coli or nitrogen, that sewage plants can put into the environment.
The legislation - should it pass in its current form - will see regional councils provide consents for sewage treatment plants based on the new standards rather than their own assessments.
It means some councils may end up being held to a lower standard under the new regulations than they were previously.
The changes are part of the Water Services Bill - currently open for consultation - and fall under the government's replacement to Three Waters, 'Local Water Done Well'.
Taumata Arowai insists new parameters - which differ depending on where the treated sewage ends up (eg lake, pond, river, estuary, coastal or open ocean) - will introduce consistency to an ad-hoc system, providing a clearer picture of environmental health.
But scientist Dr Mike Joy told Nine to Noon the "one-size-fit-all" approach was flawed and ignored the variation and sensitivity that existed between and within water catchments.
He said while some councils would be forced to lift their game, others would have their standards lowered.
In his submission on the Water Services Bill, the Parliamentary Commissioner for the Environment, Simon Upton was supportive of simplifying sewage treatment but said the current bill was inflexible.
Upton said the new limits should be a baseline and suggested a revision to the bill to allow regional councils to impose more restrictive provisions than the national standards, but not weaker ones.
Joy said the new standards would not effectively measure the impact of pollutants on the environment, because the proposed limits did not apply to the amount of contaminants in the water, but to the treated sewage inside the discharge pipe.
He also did not put much stock in using an annual median to set the standards because it would obscure sewage discharges with high concentrations of contaminants.
He maintained a better standard would be set by the maximum level of pollutants or mass load allowed in the waterway.
"Medians are a stupid measure because you can have extremes. It should be maximums not medians."
Once-in-a-generation opportunity - Taumata Arowai
Taumata Arowai head of strategy Sara McFall said the legislation was a once-in-a-generation opportunity to fix a broken system.
She said the current bespoke system was not working and national standards would enable better enforcement.
"There's no national consistency, each plant is different, even in a region, and that means that we've got no sense of what good looks like.
"We've got no baseline and we can't actually say how treatment plants are performing because of inconsistent monitoring ... we see very little enforcement of breaches."
McFall said limiting the concentration of pollutants in the sewage discharge pipe, was not a new approach and ensured consistent monitoring and enforcement.
The changes were designed to protect the environment and human health and would be expected of modern plants, with recent consents, she said.
According to Taumata Arowai, 60 percent of the public sewerage network needs to be reconsented in the next decade and 20 percent of plants were operating with expired consents.
McFall said the new national standards would also reduce consenting costs by 40 percent - saving on staff time, technical assessments, feasibility assessments and legal costs.
Taumata Arowai's consultation is out until 24 April.
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