Wairau Valley Aquifer

Wairau Valley is the westward extension of the Wairau Plain. The area is dominated by two features: the Wairau Fault and the Wairau River.

The fault runs parallel to State Highway 63 and has a major influence on local water flow patterns, and the chemical makeup of the groundwater.

A distinction is generally made between the groundwater above and below the river terrace near State Highway 63. This boundary reflects the occurrence of more permeable gravels closer to the river, which in turn host higher yielding aquifers.

It was previously thought that the Wairau River was the driving force in recharging the groundwater on the lower river terrace. However, it is now known that water originates as recharge in the Southern Hill catchments.

Currently, the highest demands on groundwater in the Wairau Valley area are for crop irrigation and municipal supply. Water demand in this traditional dryland farming area is increasing with the growth in vineyard and dairying.