Currently, the water supply capacity for Wellington can cope with a resident urban population of 377,000 during summer. The regional council plans to spend NZ$1.5M (US$1.03M) in the next 15 months exploring options to extend that capacity to 450,000.
At present three stages of expansion were being considered, with a short-term fix involving taking more water from the Hutt river via a new intake at Te Marua, or from existing water flow at Kaitoke weir.
The long-term solution appears to be the option of building a dam in one of three sites; Skull Gully in Wainuiomata, Pakuratahi river upstream from Kaitoke, or on the Whakatikei river 5km beyond where it meets the Hutt river. These options are expected to cost between NZ$42M (US$28.8M) and NZ$86M (US$58.9M).
