Farmers are being asked to check their private drinking wells after reports of a contamination scare.
Environment Canterbury monitoring and regulations director Ken Taylor confirmed the regional council was investigating a farm near Geraldine, which sourced its drinking water from a private shallow well.
The well had recorded levels of nitrates and heavy metals above the recommended health standard. "It is likely that similar contamination occurs elsewhere in the region but it would be limited to very localised areas," Taylor said. "However, what's happened in that well was unusual.
"The toxic levels were very, very high. We're checking the records and files for history of land use to get some background on this."
South Canterbury medical officer of health Dr Daniel Williams said the landowner had informed ECan and Community Public Health, after their own private testing had produced "concerning results". However, Williams said there had been "no reported health problems" as a result of the contamination.
Taylor said ECan sampled about 300 private wells per year.
"The water quality in these wells is generally very good but there are a few wells where the water does not meet drinking water standards.
"For people who rely on a private well for their drinking water supply, it is important they are aware of the history of the land use around the well and that they have their water tested."
Taylor would not confirm the owner of the well under investigation. "We are working with the landowner to gather information that will help to identify the likely source of water contamination that was found in the well.
"When we know more about it, we can then determine what we need to do next to manage the risks," Taylor said.
In ECan's last survey of groundwater wells, five of the 37 wells surveyed in the Orari-Opihi-Pareora catchment had nitrate levels above the recommended health standard, along with two of 25 in the Lower Waitaki-South Coastal Canterbury catchment, and one of 13 in the Upper Waitaki.
Taylor said shallow groundwater should not be assumed to be safe to drink.
"There is a pattern of rising nitrate levels in groundwater but this instance isn't necessarily connected," he said.
"If someone relies on a shallow well for drinking water, they should make themselves aware of what has occurred historically around the well as well as anything that could contaminate the supply now, and they should make sure the well is protected against future contamination."
- The Timaru Herald