Tiny Insects Show Taranaki's Freshwater Quality Improving

8 April 2016

Taranaki’s latest freshwater quality monitoring shows ecological health for the region’s waterways is continuing to improve, recording some of the best results ever in the past 19 years.

Ecological water health is largely determined by macroinvertebrate monitoring, the number of tiny insects and species found in streams. Taranaki’s 2014-15 results of macroinvertebrate (MCI) monitoring show some Taranaki sites have the best ever results since records began in 1995. These latest results were released in March 2016.

MCI is a nationally recognised measure of water health, used by many regions, which TRC scientists helped develop in the 1980s. MCI assigns a score to each species (from 1 -10), based on its tolerance or sensitivity to organic pollution, then calculates the average score of all species present at a site to rate the water quality.

Currently more than half of monitoring sites (29 out of 57) are in the two positive categories for water health - 22 have a positive and very significant MCI trend, up from 15 just three years ago, and a further seven sites have a significant positive trend.

There are no ecological monitoring sites in Taranaki showing significant negative trends.

There are also more than four times as many sites showing strong, significant improvement compared to 7 years ago.

Taranaki streams and rivers showing the strongest evidence of MCI statistical and ecological improvement in water quality are:

- Kaupokonui Stream upstream of the Fonterra Kapuni factory

- Mangaehu River at Raupuha Road

- Punehu Stream at SH45

- Kapoaiaia Stream at Wiremu Road

- Mangawhero Stream upstream of Waingongoro River confluence

- Kaupokonui Stream upstream of STDC Kaponga WWTP

- Kapoaiaia Stream at Wataroa Road

- Mangati Stream at Bell Block.

The full technical report, titled Freshwater Macroinvertebrate Fauna Biological Monitoring Programme 2014-2015 can be seen here: http://www.trc.govt.nz/assets/Publications/state-of-the-environment-monitoring/environmental-monitoring-technical-reports/1603850w.pdf

The findings were presented to the Council’s Policy and Planning Committee on 17 March 2016.

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