Monitoring nitrate in groundwater

Nitrate nitrogen is a stable form of nitrogen found in freshwater ecosystems; it is highly soluble and can be readily used by aquatic plants and algae for growth. Nitrate occurs naturally in New Zealand groundwaters but generally at very low concentrations. However, nitrate can leach through the soil and enter groundwater systems in high concentrations in areas of intensive agriculture and horticulture.

Elevated nitrate concentrations in groundwater are a health risk to people if the groundwater is used for drinking water. It is also an issue where groundwater feeds into rivers and lakes.

High nitrate in surface waters can result in eutrophication (excessive nutrients), which can lead to extensive growth of aquatic plants and algae. In turn, this can degrade the aesthetic, recreational and ecological values of a water body. At high concentrations, nitrate can be toxic to aquatic life.