No.20 2006

Measuring the state of groundwater
Some of the Leeston wastewater treatment ponds and border-dyked disposal areas in pasture.(Photo: Graham Fenwick, NIWA)
The effect of contaminants from land-use activities on groundwater ecosystems has long been suspected. Until now, however, these effects have not been systematically measured.
The first results from seven new research wells on the Canterbury Plains have confirmed that groundwater fauna differ depending on their location relative to a land–based wastewater disposal site at Leeston.

Water resources outlook (December - February)
The following soil moisture levels & river flows are likely:
Northern North Island: normal or below normal soil moisture levels; normal river flows
Southwest North Island: normal
Southeast North Island: below normal
Northern South Island: normal or below normal
Eastern South Island: normal
Southwest South Island: above normal

The state of our rivers
Measured trends in nitrate levels in New Zealand rivers since the National Water Quality Network began in 1989.
Our rivers are showing the benefits of efforts to clean up point-source pollution, but the effects of diffuse run-off from intensified agriculture are becoming increasingly apparent.
NIWA scientists from the National Centre for Water Resources recently completed an assessment of current state and recent trends in river water quality for the Ministry for the Environment.

Tracking water quality changes in the Manawatu River
Levels of total nitrogen have increased by 1–2% per year, with similar trends at all three sites on the river.
There have been significant improvements in water quality in the lower Manawatu River over the last 15–20 years.

Water resources review (September - November)
River flows
September–November river flows
Low river flows occurred in the upper North Island, and the northeast and southeast of the South Island. There were record lows for this time of year in Northland.
Above normal river flows were measured in Wellington, Wairarapa, the West Coast, and catchments draining the Southern Alps.
Flows were near normal in the central North Island.
[Water resources information provided by NIWA field teams, regional and district councils, and hydropower companies.]