A feature of New Zealand’s early European history is the large number of severely damaging fires that broke out from time to time.
Closely built timber buildings in Petone had suffered this fate and so a dam was required to provide water of sufficient pressure and volume.
The waters of the Korokoro stream were already in use by the Petone Woollen Mills when the dam was proposed and so a small weir was built on the lower reaches to drive a turbine at the mill.
Early Maori used this route to link to the west coast of the Wellington region.
Cornish Street, Petone, just off SH2 is a good entrance spot and has the flattest walking through the entire Korokoro Gorge. From Cornish Street it's about 3 hours return to Korokoro Dam.
Go on a waterfall hunt - there are six hidden in native bush around the Hutt Valley.