Insect poo makes 80% of Taranaki rivers unsuitable for swimming

Rivers flowing through urban parks and reserves have often already been contaminated by farmland upstream. Photo / Provided

According to a new assessment by the Taranaki Regional Council, continued faecal insect contamination has left only a fifth of Taranaki rivers clean enough to swim in.

The 20% of rivers safe for swimming is only half of the 39% previously estimated by the Department for the Environment (MFE) in computer modeling four years ago.

The new estimate is probably more accurate: the council’s policy and planning committee was told it came from region-specific modelling, while the earlier MFE figure was based on a national model.

The government’s new national freshwater standards predict that 80% of major streams and rivers will be swimmable by 2030 and 90% by 2040.

Some river mouths have permanent signs warning of health risks from bacterial loads where waterfowl have added to agricultural impacts.  Photo / Provided
Some river mouths have permanent signs warning of health risks from bacterial loads where waterfowl have added to agricultural impacts. Photo / Provided

The new Land Water People (LWP) assessment revealed levels of Escherichia coli (E.coli) bacteria would need to be reduced by 80% to meet swimming standards.

Committee chair Charlotte Littlewood said the numbers were a challenge.

“It’s quite a divisive document and so whoever is around this table after the election, there will be a lot of work to do.”

The paucity of TRC test sites means that there is uncertainty about the E.coli figures, but a memorandum from the council’s director of environmental quality, Abby Matthews, insisted action would be needed to meet freshwater standards.

“Councils should use the best available information and take all possible steps…Decision-making cannot be delayed on the basis of incomplete data and information, or uncertainty.”

Meeting bathing targets would be a “significant” and “significant” challenge when developing a regional plan to give effect to the National Policy Statement for Freshwater Management (NPS-FM).

Matthews told the committee to reduce E.coli where people most often came into contact with water would make rivers safer as sources of kai, as well as for bathing.

“There will be two things we will look at: one will improve… particular bathing sites and the other will look more broadly across the wider range at what we can do to reduce E.coli.”

She said the NPS-FM requires councils to set limits on the use of natural resources, reduce E.coli but the new report had not considered the necessary restrictions.

“Most of the actions are pretty well known: keeping stock out of waterways, improving effluent discharge, looking at critical source areas on the farm – so dairy barn effluent, walkways, places like that – will always be your best shot for money.”

As dairy farm resource permits expire, the TRC prohibits effluent discharges into water, and the board expects at least 85% of effluent permits to require disposal on soil by 2025, compared to about 60% in 2021.

Taranaki's mountain streams are not safe for swimming by the time they reach the coast.  Photo / Provided
Taranaki’s mountain streams are not safe for swimming by the time they reach the coast. Photo / Provided

E.coli lives in the intestines of warm-blooded animals and is transported in the faeces to waterways.

In itself it is not necessarily harmful, but in rivers it indicates that other pathogenic bacteria, viruses and protozoa are also present, such as campylobacter.

High E.coli levels in a few Taranaki estuaries are blamed on wild birds, but most test sites are contaminated by farm animals.

In 2018, the MFE estimated that TRC’s action could see two-thirds of the lengths of Taranaki’s largest streams and rivers become swimmable by 2030.

The TRC said this was unrealistic and instead set a target of around half of these waterways.

But Matthews says that was before NPS-FM came out and the focus may change as the board consults with the community – including hapū and iwi.

“The [LWP] The report does not consider what kinds of limits on the use of resources could be used… how the limits could be implemented, on what timelines and what implications, if any, it might have on other values ​​and outcomes.

“These will be matters for the council, tangata whenua and our community to consider.”

Matthews said the report would be part of a wide range of information from the council and beyond.

“In addition to other sources of data, information and knowledge relating to the state of our environment…this report will help inform discussions with iwi and hapū.”

This year’s TRC State of the Environment report – the first since 2015 – found that only two out of 15 Taranaki sites met the bathing standard, both located just downstream from Te Papakura o Taranaki National Park. .

Trends over 25 years have shown E.coli improves in two out of 10 sites and deteriorates in six. Over a 10-year period, two of the 13 sites improved while nine deteriorated.

A 2018 NIWA report for the TRC found that planting along streams and keeping stock out of waterways had reduced E.coli levels, but not enough to make rivers safer.

“The changes in concentration have not yet been large enough to result in improved swimming; the percentage of sites meeting current NPS swimming criteria has remained low (27%) since 2000.”

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