Fears for Te Waikoropupū Springs but council disputes nitrate trend
Monday, 7 October 2019
Regular testing of the clear water of Te Waikoropupū Springs leaves 'no room for doubt' nitrate levels have climbed over the past three years, says a volunteer sample taker.
Andrew Yuill, who has been collecting water samples for community conservation group Friends of Golden Bay since February 2016, said 600 readings made it clear.
'It's going up.'
Yuill said the level in Main Spring had risen from 0.40mg/L of nitrate-nitrogen in 2016 to 0.49 in recent tests.
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However, Tasman District Council environmental information manager Rob Smith said data provided for a Water Conservation Order hearing in 2018 showed the range of nitrogen levels for the springs had been between 0.29mg/L and 0.66mg/L over the past 40 years.
'One reading at 0.49mg/L does not define the trend or fairly represent what is actually happening and it is only one of the elements that goes to defining water quality,' Smith said.
'The council continues to monitor the water quality at the springs as part of our regional environmental monitoring with samples collected every three months from as far back as 1990.'
However, Yuill said there had been two readings of 0.49 in August – on the 13th and 27th. They followed an initial reading of 0.49 on October 23, 2018.
Recent results for Fish Spring were also causing concern, he said.
Nitrate levels in Fish Spring had generally been lower than Main Spring since Friends of Golden Bay started testing but 0.50 was recorded on August 13 and 27. 'We have never before seen a nitrate level of 0.50 in either spring.'
Yuill said he was so concerned by the readings for both springs from the August 13 and 27 tests, he asked for them to be rerun. The same results came back.
Save Our Springs co-ordinator Kevin Moran said as nitrate levels increased so did the possibility of pond slime and algae blooms.
'Nitrate pollution also threatens the tiny creatures that clean the Arthur Marble Aquifer,' Moran said. 'It's important to understand the exact level that will cause a disaster is not known but the higher nitrate levels rise, the greater the threat to Te Waikoropupū. The springs are unique in the world. If we wreck them, we have nothing to replace them with.'
Te Waikoropupū Springs contain some of the clearest water ever measured. They are the largest freshwater springs in New Zealand and the largest cold water springs in the southern hemisphere. To Māori, the springs are sacred. Ngāti Tama has had the role of kaitiaki, or guardian, over the land and the springs since before the 1840s.
Ngāti Tama Ki Te Waipounamu Trust is a joint applicant with Yuill for a Water Conservation Order to protect the springs, the aquifer and associated water bodies. The hearing before a Special Tribunal closed in August 2018. A report from the tribunal will go to the Minister for the Environment.
Yuill said he believed the most plausible source of the nitrates in the springs was urea, a nitrogen fertiliser used by the farming community.
The natural environment was very responsive to minute levels of nitrate, he said.
'If I was in charge of policy, I would be saying this [nitrate levels] has got to improve,' Yuill said. 'They don't keep records of how much nitrogen is applied.'