Hon Dr Nick Smith
Minister for the Environment
23 February 2017
Claims of lowered water standards wrong
Claims by some organisations that the Government’s proposed standards for improving water quality are lower and accept a
higher chance of infection are incorrect, Environment Minister Dr Nick Smith says.
“The 2003 Ministry of Health guideline of not swimming when the level exceeds 540 E. coli/100ml remains. The 2014 NPS
included in bold the statement that this is the ‘minimum acceptable state’ for swimming and it remains so.
“The confusing feature of the 2014 table is that it mixes the concepts of swimmability and wadeability. The 260, 540 and
1000 E. coli/100ml annual medians are all in respect of the wadeable standard. The new attribute state table applies
only to swimmability and focuses on the proportion of time a water body exceeds the 540 E. coli/100ml standard, with A
(blue) exceeding this less than 5 per cent of the time, B (green) between 5 and 10 percent of the time and C (yellow) 10
to 20 per cent of the time. The Ministry for the Environment (MfE) website further clarifies that to meet the A, B and C
attribute states, the annual median needs to be less than 130 E. coli/100ml. This means the infection rate for more than
half of the time would be less than one in 1000.
“A good example to illustrate the better approach of the new table is the Hutt River below Silverstream, for which we
have E. coli data for the past decade. It has an annual median E. coli of 100/100ml yet it exceeded the 540 E.
coli/100ml 15 per cent of the time. The 2014 NPS that focussed on wadeability would have assigned it an A attribute
state but gave no information on its swimmabilty. The 2017 NPS that is focussed on swimmability gives it a C attribute
state. The new approach is consistent with the Land, Air, Water Aotearoa (LAWA) website that today and for more than the
last month has described this spot as swimmable.
“It is grossly incorrect to claim that a swimmer in the Hutt River (classed as C/yellow), would have a one in 20 chance
of becoming unwell. The river has less than 130 E. coli/100ml for more than half the time, when the infection rate is
less than 1:1000. It is only on those occurrences 15 per cent of the time when it exceeds 540 E. coli/100ml that the
chance of infection gets to 1:20. I am also advised that the Ministry for the Environment and Ministry of Health joint
guidelines were deliberately precautionary.
“There are three good reasons for the new and more sophisticated NPS table being proposed on Human Health for
Recreation. The first is that the focus is on swimmability rather than wadeability. The second is that it connects with
the real-time information available on the LAWA website on where people can swim. The third advantage is that it is
consistent with the international risk levels for swimming accepted by the World Health Organisation, the European Union
and the United States.