The most recent groundwater quality survey was undertaken in April 2021. The purpose for this work was to improve understanding of the groundwater quality and recharge waters in the area. The report detailing the findings from the 2021 survey has been released. Download it here (pdf 2.5 MB).
The unconfined / semi-confined (leaky) nature of the aquifers in the Aorere/West Coast catchment means that the groundwater can become contaminated through a variety of pathways. Risks which can allow at pathway for contamination to enter the groundwater include inappropriate sitting of bores/wells and bore/well heads not being fully sealed. In most instances these were not intentional, but more a lack of knowledge.
Wells and shallow driven bores which access water close to the ground surface can often breach the New Zealand Drinking Water Standards due to contamination of the shallow groundwater. Contamination includes seepage of stagnant water near the bore/well, localised seepage along the edges of the bore/well, animal faecal contamination, septic tank seepage and runoff/seepage following rainfall into the bore/well.
Escherichia coli (E.coli) contamination was common in the majority of shallow wells and driven bores, regardless of their location (coastal or inland). E.coli contamination appeared to be localised. Contamination is thought to be occurring due to inappropriate bore/well siting where the bore/well was located in close proximity with activities involving faecal matter (e.g. runoff from milking sheds) or poor bore/well head protection. None of the deeper drilled bores exceeded the MAV for E.coli. All the deeper drilled bores had good bore head protection and were appropriately sited away from potential contamination sources.
If your bore wasn’t chosen for testing, but you would like to know more about your water quality, we’d be happy to provide advice on sampling and laboratory testing. Contact us here.
The results of the water quality survey including groundwater and surface water hydrological investigations will be incorporated into an Aorere/West Coast Freshwater Management Unit Water Resources Report that will inform the development of a water quality and quantity management plan.
If you have your own bore that you use for domestic/drinking purposes, please refer to the Ministry of Health links below on how to protect your bore water supply
For more information about groundwater quality and security please refer to the Ministry of Health website.
If it is a health-related question, please contact the duty Council Environmental Health Officer or the Nelson Marlborough Public Health service.
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