A report has been released assessing nitrate discharge into groundwater on the Canterbury Plains from rural land uses. Commissioned by the Canterbury Water Management Strategy Steering Group, it arose from public concern about the effects of agricultural land use on groundwater quality reports Scoop. It looks at nitrate discharge from rural land use and its implications for water quality in two situations: shallow groundwater quality on the Canterbury Plains and deeper groundwater quality for Central Canterbury. "The report provides evidence that nitrate discharge from agricultural land use on the Canterbury Plains has a negative impact on the quality of water at shallow groundwater levels, and in some situations, exceeds drinking water nitrate standards," says Ken Taylor. "It also shows groundwater quality generally improves with depths below the groundwater surface because of mixing with high quality groundwater from river recharge," he says. "Most large drinking water supplies, including Christchurch, take water from deep groundwater. In Christchurch there are two other factors that help protect water quality from land use effects. The first is the confining layers above the aquifers where Christchurch city takes its water. The second is that we are in the process of implementing land use controls over the area of land where nitrate could get into the aquifer," he says. The report will be used by the Canterbury Water Management Strategy, run by the Mayoral Forum, to help guide them and others when looking at the best way to sustainably manage Canterbury's future water resources.
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