Access by boat is easiest, however walking across (public) land is possible, followed by a sticky wade across a waist deep section of lake to the island home to this cache.
Launch trailer boats at Pairere Ski Club/Horahora Reserve, or hand launch kayaks etc from end of sealed access way at S37 58.800 E175 39.600. The island this cache is on is sometimes "joined" to the mainland by floating lake weed, however circumnavigation by kayak is usually possible. The shallows between the mainland and the island are generally calf deep mud that takes and keeps footwear. The island itself is occasionally used for Findlay Park Youth Camp adventure games, thus is substantially trampled, muddy and has a large collection of odd shoes on display (presumably the pairs are still in the mud). Please rehide the cache well due to the high risk of being muggled. If walking (not ideal, but more interesting, and an extra challenge) I recommend you carry your shoes across this section. (or better still simply get wet and float/paddle across this bit!). If walking, follow sealed access referred to above to its end, then turn south and follow farm track up the slope then a few hundred metres across paddocks to the site of the old village. This track follows the original (pre 1947) road route through the area. Climb fences beside the locked gate, and leave other gates as you find them. A few times a year this area is grazed by a large cattle mob for a week or so. Unless stock familiar, these can be intimidating, so probably best to not be in the same paddocks if you come across this situation. Usually electric fencing is only live when the cattle are there. At the old village site there are some salvaged turbine rotors and the old village water tank structure. Use you GPS and common sense to find a route to waters edge then to the cache. Beware of changes to water depth. The shallow water is between the island and the mainland.
Aerial view of the power scheme shortly before Lake Karapiro was filled in 1947.
Of note are: Access ramp/stairs to powerhouse at extreme lower left, Weir gates structure at extreme right (where 5 knot bouy is moored today off Findlay Park Camp), "new" Pokaiwhenua bridge at top left on re-routed Horahora Rd (old road went via the village then over a lower level bridge). The large flat area in the foreground is the flat top of the peninsular between Findlay park Camp "basin" and the main stretch of Lake down to the Pairere Ski Club/Horahora Bridge. The headrace extending upstream from the powerhouse has very steep sides, so beware of rapid depth changes if "walking" to the cache. Prior to the head race excavation, the river flowed in a narrow chasm similar to just above Huka Falls today. This was a vital crossing point in Maori society and early Europeans record crossing horses over a bridge formed from tree trunks over the 10m width of the channel
View of water intake side of the station. Access stair/ramps are clearly visible as bright concrete, below the transformer house building. The "head" (height from intake side to outlet side) of this station was only about 9m.
This view is of the access stairs/equipment ramp/rails extending from the powerhouse up to the transformer house and ancillary buildings. The date is 1947, and locals are viewing the rising lake water, while last minute removal of machinery takes place. The temporary horizontal elevated rail was used to extract the internal maintenance crane, which was relocated into the Karapiro station machine hall.
From a similar location but around 5m higher, in 2012 there is little evidence of the buildings and equipment that dominated the area only 65 years previously. The extent of visible ramp varies from virtually nothing at maximum lake level to around 2m at near minimum levels. The powerhouse structure remains a few metres deep even at minimum lake level.
The following article is published by IPENZ as part of a series on significant engineering projects in New Zealand:
In the period between 1890 and 1910 the thriving mining industry became an important leader in developing New Zealand’s hydro–electric power potential.
In 1896 the Waihi Gold Mining Company utilised water turbines on the Waikino River to directly drive stamping batteries which crushed the gold bearing ore. But by 1902, with the doubling of stamping capacity, water turbine driven direct current (DC) generators were installed to supply electric motor power. However, despite the building of a steam driven electric power station in 1905, the company was facing the need for additional and cheaper power to crush lower grade ore.
The original survey of the hydro-electricity potential of the Horahora rapids on the Waikato River, about 80 kilometres from Waihi, was completed in 1905 by a Waihi surveyor, named Chalmers,
The company applied for a licence to develop the Horahora site, but was declined. At that time Government had a firm view that it should develop New Zealand’s hydro potential in the national interest rather than allowing private interests to benefit.
However, in 1910 it was finally agreed that the company be given approval to build a station up to 10,000 horse power (hp), with the Government having the right to purchase the complete works at any time at an agreed valuation.
The company's scheme diverted part of the Waikato River's flow by means of a 400 metre (m) canal across a bend in the river, where there was a significant fall of level due to rapids. The powerhouse at the end of the canal made use of the resulting head of 9 m, and discharged the flow back into the river via a short tailrace.
The Chief Engineer for the Horahora hydro-electric development was Mr. Gauvain. He was well known in Waihi and Waikino as he was also the Chief Engineer of the Waihi Gold Mining Company.
The headrace was cut through an area of gravel and large boulders, and excavation was assisted by sluicing, a technique often used in mining at that time. This canal was concrete lined. A headgate at the top of the headrace was built behind the earth bank of the river, and when the time came, this bank was also removed by sluicing it into the river.
By the end of 1911 work was well in hand on the headgates, the canal and the powerhouse building, and by the end of 1912 much of the civil work had been completed.
The original installation consisted of six horizontal 1950 hp Frances turbines with the shaft of each passing through a water sealing gland into the generator room to drive a 1050 kilowatt (kW) generator. Automatic governors located in the generator room controlled each turbine by radial gates.
Siemens of Stafford, England was selected to supply the generators, transformers, switchgear and switchboards, and Boving & Company of Sweden supplied the turbines and associated gear, such as governors. The installation of this equipment was completed by late 1913. This gave a total station output of 6,300 kW
In October 1913 a groyne (later to be made a weir) was extended into the river just downstream of the headrace gates to divert water into the headrace. This enabled the station to begin commissioning equipment.
Horahora hydro-electric power station was completed in early February 1914, and its power was delivered to the Waihi mines on 8 April, 1914 by means of the just completed Horahora to Waihi transmission line.
In 1919 the government purchased the station which at that time, with the falling away of mining load, was only working at half capacity. However, with the expansion of the 50 kilovolt transmission network including connection to Auckland, increased capacity was needed. Between 1924 and 1926 the headrace, tailrace and powerhouse were enlarged to accommodate two additional 2000 kW units which enabled an output of 10,300 kW.
Horahora provided the only substantial hydro generation for the northern part of the North Island until Mangahao and Waikaremoana generation was connected to that area in 1932, and Arapuni was commissioned and operating reliably in the same year.
Horahora and its headworks were submerged with the filling of the Lake Karapiro in 1947. A well known photo shows the generators still turning as the lake level rose to drown them over the next few days.
Two of the original Siemens generator rotors now sit on a terrace above the power station site, marking the located of the former Horahora settlement. These were salvaged, along with other generator equipment, in the 1970s for scrap value of the copper and iron.
Related IPENZ Records:
Waihi Goldmining
Victoria Battery
Horahora-Waikino 50 kV transmission line
References:
John E Martin, People Politics and Power Stations, Bridget Williams Books and ECNZ, 1991
Caudelle Clarke, 'A Short History of Hora Hora and the Hydro-electric Power Development,'Ohinemuri Regional History Journal, 9 May 1968 (www.ohinemuri.org.nz)
J. B. McAra, Gold Mining at Waihi 1878-1952, Waihi, 1998
Joyce Neill, 'Life at the hydro-electric power project at Horahora,' Ohinemuri Regional History Journal, 21 June 1977.