Rārangi Shallow Aquifer

The boundaries of the Rārangi Shallow Aquifer are the Pukaka River, Pukaka Hills, Wairau Diversion channel to the south, and the Pacific Ocean.

The last boundary is the most important as mean sea level controls the rate of freshwater flow seaward.

Due to their proximity to the coast, abstraction of water from these aquifers creates the potential for seawater intrusion. This is the process whereby the boundary between freshwater and seawater can move inland.

This aquifer is the sole source of water supply for the local community. Domestic water is supplied from shallow wells. Water is also used for the irrigation of the local golf course.

The water level in the aquifer varies due to changes in topography, ranging from about 5 metres down to just above ground level in the ecologically significant wetlands. It also varies seasonally, reflecting both rainfall patterns in the Pukaka Hills and demand.