Poo bug makes 80% of Taranaki rivers unswimmable
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% of rivers safe for swimming is only half the 39% previously estimated by the Ministry for the Environment (MFE) in computer modelling four years ago.
The new estimate is likely to be more accurate: the council’s policy and planning committee was told that 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% of larger streams and rivers to be swimmable by 2030, and 90% by 2040.
The new assessment by the company Land Water People (LWP) found that levels of E coli bacteria would have to be slashed by 80%to meet the swimmability standards.
Committee chair Charlotte Littlewood said the stark numbers were a challenge.
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 that action would be needed to meet freshwater standards.
‘‘Councils must use the best information available and take all practicable steps ... Decisionmaking cannot be delayed on the basis of incomplete data and information, or uncertainty.’’
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 that 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 be looking more broadly across the wider range at what we can do to reduce E coli.’’
She said the NPS-FM required 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 dairyshed 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. The council expects that at least 85% of effluent consents will require disposal to land by 2025, up from about 60% 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 that other disease-causing bacteria, viruses and protozoa, such as campylobacter, are also present.
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 twothirds of the lengths of Taranaki’s larger streams and rivers become swimmable by 2030. The TRC said this was unrealistic, and instead set a target of about half of those waterways.
Matthews said this was before the release of the NPS-FM, and the target could change as the council consulted 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 time frames, and what, if any, implications this may have for other values and outcomes,’’ she said.
Matthews said the report would be part of a wide range of information from the council and beyond.
This year’s TRC State of the Environment report – the first since 2015 – found that 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 at two of 10 sites, and degrading to six. Over a 10-year period, two of 13 sites improved, while nine deteriorated.
A 2018 report by Niwa for the TRC found that streamside planting and keeping stock out of waterways had reduced E coli levels, but not by enough to make any more rivers safe.
– Public Interest Journalism funded through NZ On Air