Some river mouths have permanent signs warning of health risks from bacteria loads where water birds have added to agricultural impacts. Photo: Te Korimako o Taranaki
Ongoing contamination by a faecal bug has left just a fifth of Taranaki rivers clean enough to swim in, according to a new assessment for Taranaki Regional Council.
The 20 percent of rivers safe for swimming is only half the 39 percent previously estimated by the Ministry for the Environment (MFE) in computer modelling four years ago.
The new estimate is likely 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 nationwide model.
The Government's new national freshwater standards call for 80 percent of larger streams and rivers to be swimmable by 2030, and 90 percent by 2040.
The new assessment by the company Land Water People (LWP) found levels of Escherichia coli (E. coli) bacteria would have to be slashed by 80 percent to meet the swimmability standards.
The committee chair Charlotte Littlewood said the stark numbers were a challenge.
"It's quite a confronting paper and so whoever's around this table after the elections, there's going to be a lot of work to do."
The scarcity of TRC testing sites means there is uncertainty about the exact E. coli figures, but a memorandum from the council's environmental quality director Abby Matthews insisted action would be needed to meet freshwater standards.
"Councils must use the best information available and take all practicable steps... Decision-making cannot be delayed on the basis of incomplete data and information, or uncertainty."
Taranaki's mountain streams are unsafe for swimming by the time they reach the coast. Photo: Te Korimako o Taranaki
Meeting swimmability targets would be a "significant" and "prominent" challenge when developing a regional plan to give effect to the National Policy Statement for Freshwater Management (NPS-FM).
Matthews told the committee reducing E. coli where people most often came into contact with the water would make rivers safer as sources of kai, as well as for swimming.
"There'll be two things we're looking at: one'll be improving… particular swim spot sites and the other will looking 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 natural resource use, to reduce E. coli but the new report had not looked at what restrictions were needed.
"Most of the actions are fairly well-known: keeping stock out of waterways, improving effluent discharges, looking at critical source areas on-farm - so dairy-shed effluent, laneways, places like that - are always going to be your best bang for buck."
As dairy farm resource consents come due for renewal TRC is banning effluent discharges to water, and the council expects at least 85 percent of effluent consents will require disposal to land by 2025, up from about 60 percent in 2021.
E. coli lives in the gut of warm-blooded animals and is carried in faeces to waterways.
By itself it is not necessarily harmful but in rivers it indicates other disease-causing bacteria, viruses and protozoa are also present - such as campylobacter.
High E. coli levels at a few Taranaki estuaries are blamed on wild birds, but most testing sites are contaminated by farm animals.
In 2018, the MFE estimated that action by TRC could see two-thirds of the lengths of Taranaki's larger streams and rivers become swimmable by 2030.
Rivers flowing through urban parks and reserves have often already been contaminated by farmland upstream. Photo: Te Korimako o Taranaki
The TRC said that was unrealistic and instead set a target of about half of those waterways.
But Matthews says that was before the release of the NPS-FM and the target may change as the council consults the community - including hapū and iwi.
"The [LWP] report does not consider what kinds of limits on resource use might be used… how limits might be implemented, over what timeframes and what, if any, implications this may have for 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.
"Alongside 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 only two Taranaki sites out of 15 met the swimmability standard, both located just downstream from Te Papakura o Taranaki national park.
Trends over 25 years showed E. coli improving in two of 10 sites and degrading in six. Over a 10-year period, two of 13 sites improved while nine deteriorated.
A 2018 report by NIWA for the TRC found streamside planting and keeping stock out of waterways had reduced E. coli levels, but not enough to make any more rivers safe.
"Changes in concentrations have not yet been large enough to result in an improvement in swimmability; the percentage of sites meeting current NPS swimmability criteria has remained low (27 percent) since 2000."
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