Based on 2002 research by E Lens.
Water power was the preferred (almost only) option for the early gold batteries of this district.
There are remains of 25 or more water-power supply dams in the Ohinemuri. The earliest was for the Smile of Fortune Battery, Owharoa, in 1875, and the Victoria Battery continued to use its high and low level races until closure in 1952-4.
Two dams were built of masonry, the rest were of wooden construction. Their associated water races are in varying states of preservation; some would (and do) hold water today.
Much of this information can also be viewed in the GIS