Southern Marlborough Groundwater Resources
There is little evidence of the presence of high-yielding aquifers in the Lower Awatere Valley, Blind River, Waima River or Flaxbourne areas. The impermeable nature of the local geology generally precludes them.
Groundwater is supplied from shallow wells that tap thin gravel beds overlying the distinctive mudstone papa.
The papa represents the base of the aquifer and doesn't contain groundwater itself. This is represented conceptually in the diagram below.
Well yield is low compared to the Wairau Aquifer, and relies on recharge from nearby streams. When channel flow stops there are limited gravels to store groundwater.
Land in southern catchments has traditionally been used for pastoralism, but this is changing to more intensive land uses which require irrigation.
The increase in demand for water has resulted in a number of alternative approaches. These include storage dams and augmentation schemes to shift water from one catchment to another. The hydrology of this area is not fully understood compared to other parts of the district.