Starting in 1974, geological surveys were conducted to see if a new dam could be built in Reservoir Valley
When viewing old aerial photos of Reservoir Valley, one might wonder about the intricate network of firebreaks on the hillsides. The answer lies in geological surveys. The Tana Umaga Track for example was first established in the 1970s as a geological survey route to examine rock formations for a proposed dam project on the Wainuiomata River. However, the plan was ultimately rejected.
Concerns about the construction of a new dam could have included suitability of the valley’s rock structure for a stable dam, the area’s earthquake risk, and the proximity of the Homedale suburb.
In 1993, a geological survey of the Wainuiomata Valley was conducted using a stratigraphic drillhole. It revealed that the deep greywacke and argillite rocks were covered by over 60 meters of much younger, softer Quaternary sediments from the Pleistocene era.
