SC water nitrate levels still increasing

19:32, Dec 10 2013

South Canterbury health authorities are warning that nitrate levels in the region's groundwater and rivers could increase for some time.

Last week, Environment Canterbury released its amended Land and Water Regional Plan, which sets the overall guidelines for the region's land and water use.

South Canterbury's medical officer of health Dr Daniel Williams was pleased the plan aimed to limit nitrate releases into groundwater. However, he said nitrate levels would continue to increase in the foreseeable future even if the rules were implemented today.

"Our groundwater systems are large and complex. It can take some time for nitrate leaching at the surface to be reflected in increased nitrate levels in the water we extract and use," he said.

"Rural residents will still need to maintain vigilance when considering drinking water issues. We need to act now to keep our water supplies safe in the future."

ECan commissioner for water David Caygill said there was no "overnight fix".


"No one has suggested [to me] a set of measures which would prevent the situation getting worse before it gets better. It is fundamentally the legacy of past practices."

According to ECan's latest report, in the Orari-Opihi-Pareora zone five out of the 37 wells surveyed last year had nitrate levels above the recommended health standard, two out of 25 in the Lower Waitaki-South Coastal Canterbury zone, and one out of 13 in the Upper Waitaki.

"We knew this would take some time. The medical officers are quite rightly reminding people of the risks in the meantime, but that is not the same thing as saying we're doing nothing [to address it]," Mr Caygill said.

He acknowledged the plan set some of its targets "decades into the future", such as the stipulation nitrate levels in all community drinking water supplies should be below the maximum allowable by 2040. "This means we have to keep monitoring, and keep updating our practices," he said.

Mr Caygill said ECan would also continue its research into the "complex issues" which contributed to toxic algae growth in rivers and streams.

ECan's Land and Water Regional Plan will become operative later next year, subject to appeals on points of law.

The Timaru Herald