Gore Water Nitrate Levels Below National Standards
The Gore District Council is concerned publicity about Greenpeace’s testing for nitrate levels in Gore’s water supply was misleading and could cause undue concern among residents.
Late last week, Greenpeace released the findings of recent water testing in Gore and Lumsden. It stated that 41% of samples from town supplies showed nitrate levels over 4 mg/L.
Gore District Three Waters Asset Manager Matt Bayliss said these nitrate levels were consistent with the Council’s routine monitoring.
“What’s important to understand is the New Zealand Drinking Water Standards’ maximum acceptable value for nitrates, as mandated by the World Health Organisation, is 11.3 mg/L.
“So, our testing and Greenpeace’s, have returned levels well below national and international standards.”
While the Council was not concerned about the current nitrate concentrations in Gore’ss drinking water supplies, he said it would be if these concentrations were to increase.
Due to their location, the nitrate levels in the two bore fields supplying Gore’s water were quite different.
At the Cooper’s Well bore field, which supplies approximately 65% of Gore’s water, the average nitrate concentration over the past 10 years was 4.8 mg/L.
The average nitrate concentration in the Jacobstown Well bore field, which supplies approximately 35% of Gore’s water, was 1.4 mg/L over the same period.
“We’ve taken steps in the past and are looking at future solutions to address nitrate levels in our drinking water supplies.”
Between 2009 and 2016, the Council went through a lengthy process to designate approximately 17ha of land surrounding Cooper’s Well to protect the water supply.
More recently, it has been working on centralising the treatment of water from Cooper’s Wells and Jacobstown at the East Gore Water Treatment Plant.
“Given the Jacobstown bore field has much lower nitrate concentrations than Cooper’s Wells, blending these water sources will reduce nitrate concentrations in Gore’s water supply.”
Currently, only water from Cooper’s Wells is treated at the East Gore plant. To centralise water treatment, the Council needs to install a pipeline connecting the Jacobstown bore field, on the west side of the Mataura River, to the East Gore treatment plant, Mr Bayliss said.
The Council’s only other urban water supply was for Mataura.
Mr Bayliss said the average nitrate concentration in water from the Pleura Dam, the source of Mataura’s drinking water, has been 1.7 mg/L over the past three years.
“It’s also worth noting that the average nitrate concentration in the Mataura River, which is used as a supplementary supply for both Gore and Mataura water supplies when the primary water sources cannot keep up with demand, has been 1.3 mg/L over the past three years,” he said.