Since 1925, the Orongorongo Catchment has been a vital source of
potable water to the greater Wellington area. The upper Orongorongo
Catchment has been closed to public access since the 1920s and, due to
its undisturbed nature, the upper catchment has a natural high water
quality.

This report has focused on those tributaries used for water supply.
Rainfall and climate data have also been statistically analysed.