The presence of high levels of arsenic in Marlborough groundwater has only been discovered as recently as 2001. A knowledge of its occurrence in the groundwater we drink is very important as the long term consumption of groundwater with concentrations above 0.01 g/m, or parts per million, is toxic to human health.
All of the research to date points to a natural source with the exception of isolated sites linked with historic land uses such as landfills or sheep dips. The treatment technology exists to remove it or reduce arsenic levels in groundwater to safe concentrations.
The below figure shows the distribution of measured arsenic concentrations for the Rārangi Shallow Aquifer, where most of the intensive research by Marlborough District Council has occurred.
