The NIWA-operated National Rivers Water Quality Network (NRWQN) is New Zealand's only national water quality monitoring tool.
Established in 1989, NRWQN data is collected from 77 sites on 35 rivers around New Zealand. These rivers drain about 50% of New Zealand’s total land area.
Monthly measurements are made on:
- flow
- temperature
- water clarity
- the presence of nutrients
- microbial quality.
NRWQN data over the last 20 years shows that water pollution has been decreasing. This is thought to be a result of improved wastewater treatment. However, over the same period water quality has deteriorated due to the rapid increase of nutrient levels in many New Zealand waterways. The source of this problem is the intensification of agriculture.