National water quality targets for Taranaki rivers 'overly optimistic'

Thursday, 15 March 2018

Taranaki regional Council say government swimmability targets for Taranaki rivers were optimistic.

An expectation that almost 70 per cent of rivers in Taranaki will become swimmable within 12 years was unrealistic, a Taranaki Regional Council committee meeting has been told.

An obligation under the amended National Policy Statement for Freshwater Management (NPS-FM) released in 2017 targeted 80 per cent of rivers and lakes nationwide to be swimmable by 2030, rising to 90 per cent in 2040.

A government report estimated only 39 per cent of Taranaki rivers were swimmable.

The Ministry for the Environment (MfE) required the council to set regional targets that would show how the region will support the national target.

A taskforce has used computer modelling to predict the effects of the council's water quality management interventions, but the council considers the projections to lack credibility, TRC environment quality director Gary Bedford said.

Riparian planting now covered 14,500km of stream banks on the Taranaki Ring Plain.

* Farmers' efforts to be assessed as riparian scheme deadline looms**

Draft regional targets are expected to be made public by March 31, and final target by December 31 this year.

The target set by the MfE taskforce would not be reached in Taranaki, Bedford said.

Bedford said the computer modelling used by the MfE was 'overly optimistic' and a more realistic target for the regions waterways would be '50 - 55 per cent.'

The taskforce had estimated barely 39 per cent of Taranaki rivers, and 97 per cent of lakes, were currently swimmable, he said.

The council was concerned the national targets ignored both seasonal and river flow changes when measuring E.coli in waterways, and other contaminants such as nitrogen and phosphorous.

The taskforce modelling for Taranaki rested on more dairy shed effluent being discharged onto land in the future than into waterways from treatment ponds.

It also failed to reflect peak flow, not baseline, conditions which gave the highest concentrations of E.coli - even though these in turn are used to measure 'swimmability' under the NPS-FM, Bedford said.

MfE recently confirmed the NPS-FM was going to be reviewed to take into account seasonality/flows, he said.

'In the meantime the council was still obliged to apply the NPS criteria as they currently stood.'

The council's own freshwater modelling data showed E.coli levels in rivers were higher in winter when effluent was not being discharged from effluent ponds than under identical flow and weather conditions in summer.

The Maketawa Stream, which had minimal pond effluent discharged into it, had a higher bacteria count in winter when water levels were low than in summer under the same conditions, he said.

The water quality in the stream dropped to its lowest in winter when levels were high, he said.

A target of 50-55 per cent of rivers in Taranaki being swimmable by 2030 was more realistic and more appropriate target to aim for - and better reflected the anticipated outcomes of the council's water quality enhancement interventions, he said.

Bedford said the region would 'fall well short' of the optimistic NPS-FM targets in spite of the efforts of the council's successful riparian planting scheme.

The programme had seen 4.7 million plants covering 14,500km of stream banks, and included 99.5 per cent of dairy farms on the ring plain, since it was established in the early 1990s.