Freshwater studies point to improvements

New scientific studies of data from Taranaki and nationwide have concluded that freshwater quality is better than many probably believe – and this region in particular has been taking effective steps to achieve improvements.

“These findings bring more clarity to the public discussion on freshwater quality,” the Taranaki Regional Council’s Director-Environment Quality, Gary Bedford, says of the studies by NIWA and Land Air Water Aotearoa (LAWA). “They also highlight the dangers in adopting a ‘one-size-fits-all’ approach to freshwater management.”

The independent study by NIWA found that Taranaki’s long-running riparian protection programme is not only strongly associated with improved ecological health in the region’s waterways, but has also reduced E. coli levels.

Guided by solid previous research, improving stream ecological stream health has been the major goal of the Council’s long-running and voluntary riparian fencing and planting programme. The NIWA report endorses and validates this approach, with reduced bacterial (E. coli) contamination being an additional benefit.

Mr Bedford says the NIWA report is significant nationally as well as regionally. “As the authors themselves noted, it was a rare opportunity for them to engage in leading-edge research. 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 resulting dataset can be analysed with confidence.”

He says a notable finding is that ecological health is improving even where nitrogen levels are increasing. “This shows that the relationship between nutrient levels and stream health is clearly not as simplistic and straightforward as often suggested, and generalised regulations may not necessarily result in better water quality at specific locations.”

The study also raises questions about New Zealand’s new swimmability regime. According to NIWA’s assessment, Taranaki’s rivers and streams are well above minimum European standards for recreational water quality, but they do not meet this country’s new ‘swimmability’ criteria.

“The report notes that under river conditions that are suitable for recreational use, only 27% of Taranaki’s waterways are swimmable under the New Zealand swimmability criteria. But if European standards are applied, more than 80% would be suitable,” says Mr Bedford.

He says this is particularly interesting in the light of the Government’s emphasis on riparian fencing as a key measure to attain swimmability.

Meanwhile LAWA, a collaborative web-based venture involving central and local government and independent scientists, has published a new analysis showing water-quality improvements both nationally and regionally over the past decade have been greater than widely appreciated. 

This report finds that for every monitored aspect of freshwater quality in the decade to 2016, more sites showed strong evidence of improvement than degradation. The report’s author, Cawthron Institute’s Dr Roger Young, says the findings ‘could represent a turning point in New Zealand’s river health story’, though he cautions that much more work needs to be done.

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

Both the NIWA report and LAWA report were discussed by the Council’s Policy and Planning Committee today.

NIWA report: www.bit.ly/RiparianReport2018 (PDF, 2.3 MB)

LAWA report: www.lawa.org.nz/explore-data/river-quality/#/tb-national