Water Quantity

Approximately 470 million cubic metres of water is allocated via about 680 resource consents in the Wellington region. About two thirds of this is from surface water sources although there are many more individual groundwater consents than surface water consents. 50 percent of all allocated water is for town supply while a further 25 percent is allocated for irrigation.

Allocation (i.e. consented abstraction) more than doubled in the Wellington region between 1990 and 2010, primarily due to increases in irrigation demand in the Wairarapa. Most of the major rivers and streams in the region are now fully allocated or close to full allocation.   The most productive groundwater aquifers are also highly or fully allocated.   

Recent resource investigations in the region have improved our understanding of the linkage between groundwater and surface water.  Management policies have been refined to take this linkage into account and ensure that the impacts of groundwater abstraction on rivers, streams, springs, lakes and wetlands are addressed when setting allocation limits.  Avoiding salt water intrusion at the coast as a result of groundwater drawdown is another key part of management policies.

Large scale damming and diversion of water for hydropower generation does not occur in the Wellington region. Additional water is available to allocate at higher river flows (i.e. flow harvesting for storage) and there are several farm scale schemes in the Wairarapa.  However, to date, no large scale water storage reservoirs have been developed.

Data on actual use of water (as opposed to maximum consented use) is improving all the time as water meters become mandatory. As this actual use data becomes more complete over time it will help understand true pressures on the water resources and help to refine policies and rules that govern the management of water.