An independent study had found riparian planting was helping clean up Taranaki rivers and streams

Taranaki river water quality met European recreational clean water standards - but fell below national standards set for swimming in New Zealand, an independent scientific report commissioned by the Taranaki Regional Council showed.

A National Institute of Water and Atmospheric Research report found a strong correlation between riparian planting along streams and river in Taranaki during the past 20 years, and improved water quality and lower E.coli levels, the regional council policy and planning committee was told on Tuesday.

Council environmental quality director Gary Bedford said the scientific data analysed in the reports showed the water quality in the region was better than many expected.

STUFF Riparian planting in Taranaki has helped lower nutrient levels in streams over the past 20 years

The "robust, authoritive and independent" study was an "exhaustive analysis" which validated the council's riparian planting programme in helping reduce nutrient levels in streams and rivers, he said.

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Bedford said the study reflected the real world "we live and operate in".

SUPPLIED/TRC Taranaki Regional Council provides native shrubs and trees for farmers to plant along stream banks

It also raised questions about the government's 'swimmability' criteria, he said.

The NIWA report showed Taranaki's rivers and streams were above the minimum European standards for recreational water quality.

But these standards did not meet New Zealand's swimmability' criteria, he said.

Under national standards, only 27 per cent of Taranaki rivers were safe to swim in.

However, if judged under European standards the number of rivers safe to swim in rose to 80 per cent.

"These findings bring more clarity to the public discussion on freshwater quality, and also highlight the dangers in adopting a 'one-size-fits-all' approach to freshwater management."

The NIWA report found that the region's long-running riparian protection programme had help improve ecological health in Taranaki's rivers as well as reduce E.coli levels, he said.

Bedford said improving ecological stream health had been the major goal of the voluntary riparian fencing and planting programme which was endorsed.

A reduction in E.coli contamination in rivers was an additional benefit of the programme.

Bedford said the NIWA report was leading edge and both regionally and nationally significant, and unique in the world.

"It was a rare opportunity for the scientists to be involved," he said.

"Nowhere else in the world, let alone New Zealand, has a study reviewed a situation where riparian fencing and planting has been carried out on such a wide scale and for so long."

The study also found stream health improved when nitrogen levels in the water increased.

"This shows that the relationship between nutrient levels and stream health is clearly not as simplistic and straightforward as often suggested," Bedford said.

"Generalised regulations may not necessarily result in better water quality at specific locations."

A LAWA report showed there had been greater improvements in water quality, nationally and regionally, over the past decade than expected.

The report also showed no clear trend in Taranaki for total nitrogen, or E.coli, reductions in nitrate levels, and overall reductions in ammonia and phosphate levels during this period.