A South Taranaki stream is showing improvements in its ecology as a result of more riparian planting along the stream bank margin which was reducing nutrients entering the water.
The Waiokura Stream, near Manaia, has been part of a nationwide research survey of five best practice dairy catchment streams since 1994.
A recent report to the Taranaki Regional Council policy and planning committee showed the lowland stream, which is fed by groundwater from beneath intensively farmed dairy pasture, had the best water quality of the other five sites tested.
* Health of Taranaki waterways continuing to improve, council monitoring shows
* Soil scientist: Too much fertiliser behind pollution crisis
* Dairy farmers unfairly cop the blame over water quality
* Fish and Game to call for nitrogen cap
The other sites in the survey are in the Waikato, West Coast, South Canterbury and Otago.
Regional council environment quality director Gary Bedford told the meeting the report showed changing farm practices which had reduced the amount of nutrients entering stream had helped improve the water quality over the past two decades.
The improved water quality resulted in an increase of tiny macroinvertebrate insect species in the stream, particularly in the past two years, he said.
The stream was the only catchment from the five sites which showed an increase in macroinvertebrate numbers.
Nitrogen and nitrate levels had decreased significantly in the stream in the last two years in spite of increased use of urea in the catchment.
In 2012 tests showed nitrogen levels had increased 14 per cent in the stream during the previous eight years.
E.coli and suspended solids concentrations had also decreased as the water clarity had improved above all other sites.
In contrast there was no changes in phosphorus levels, the report said.
The changes highlighted the importance of having appropriate riparian planting as a “core component” of water quality management, the report said.
Fencing and planting along the stream bank and diverting dairy pond effluent were seen as key measures to promoting stream health.
Over the past two decades there had been increased riparian planting along the stream bank, as well as less phosphate fertiliser applied.
Dairy shed effluent, which was once put into the stream, was now put onto the land.
Fish and Game Taranaki officer Allen Stancliffsaid fencing off small streams helped reduce pugging and nutrient run off after heavy rain.
“If the indicators proved the water quality is improving, it was encouraging signs for the future,” he said.