Wellington Region

This zone comprises three water resource units in the southwestern part of the region that are neighbours but hydrologically discrete from one another.

The first area comprises the collective catchment of streams that drain the hills around Wellington city into the harbour as well as the open sea. Consents for abstractions are limited to minor takes for golf courses and short term abstractions for large earth works projects (e.g. windfarms). The greatest pressures on streams in this zone relate to runoff from urban and low intensity farming areas as well as the heavy modification of stream channels in the city suburbs.

On the opposite side of Wellington Harbour are the Wainuiomata and Orongorongo river catchments. These neighbouring catchments drain the Rimutaka and Orongorongo ranges, respectively, in a north-south direction and discharge to the Cook Strait. Both are subject to significant river abstractions in their headwaters for municipal supply. The Orongorongo River catchment lies entirely within the Department of Conservation estate and is therefore not subject to any further abstraction pressure beyond the municipal take. 

The most prominent water resource in this zone is the Hutt River and its associated aquifer system underlying the Hutt Valley. The Hutt River is the third largest in the region (after the Ruamahanga and Ōtaki rivers) and is subject to the largest run-of-river individual abstraction. This abstraction occurs in the headwaters and forms the majority of the municipal supply to Wellington and Porirua cities. Several significant tributary rivers join the Hutt River downstream of the abstraction such that the initial flow depletion is regained to an extent.

Management of water resources in the Hutt Valley is focussed on treating surface and groundwater as a single, connected system.