The dams that never were,Otipi Road is an adventurer’s dream
FEW New Zealand roads would be as remote. From the coast east of Opotiki, you twist up the gravel of the Motu Road, once an epic stage of the Rally of New Zealand.
At Toatoa, where the post office and school have long gone, you veer onto the even quieter Takaputahi road, past farmland that’s being reclaimed by bush. After 10km, you reach the Whitikau Forks DOC camp spot. Across a stony ford, Otipi Road begins.
Over the next 19km, the logging-type road snakes up through the wilderness, peaking at 900m altitude and plunging over 600 vertical metres to the Motu River, where you could fairly claim to be miles from nowhere.
Otipi is a thrilling, lung-bursting, leg-aching mountain bike ride that links in with the popular Motu Trails. Hunters and rafters also drive the road, though in places, it must be seat-of-the-pants stuff.
Otipi was built for a planned hydroelectric power scheme. In late-2012, I talked with Buck Alley, who led Ministry of Works and Development hydroelectric investigations in 1956-1963; and with Colin Cardiff, who was involved in a second round of Ministry of Works investigations from the late-1970s.
Buck recalled that in the 1950s, the Ministry was keen to establish hydro potential around the country so investigation parties were established for the field work. As well as the Motu, there were assessments of Central North Island rivers such as the Mohaka, Whakatane and Rangitaiki (the only dam stations built were on the Rangitaiki).
Buck’s team started out with six or eight men.
“The initial plan was to get the levels and flow for the whole Motu river, to find out what the power potential was,” he said.
This included exploring the possibility of diverting water from other catchments.
A major challenge was lack of information. “There were no existing contour maps, just Lands and Survey boundary maps and major triangulation stations, and some aerial photos that had been taken after the war. We had strips of these photos, but there were no [topographical] levels on them. One of the jobs was to establish survey bench marks throughout the catchment so that the photos could be used to plot contour plans.”
In June 1957, a helicopter was hired for reconnaissance. The plan was to start at the mouth of the Motu river, 45km east of Opotiki, and head inland, looking for possible dam sites.
“Unfortunately, the helicopter was pranged in a tight landing spot. The tail rotor touched a rock. Fortunately nobody was hurt, but the chopper was a write-off. We were stuck in the bush for a couple of days. A plane dropped us a raft and some food, and we floated out to the Motu bridge. I remember floating down the river under moonlight.”
Helicopter RapidGet a detailed map, and follow the line of the Motu upstream of Mangatutara, and you’ll find the crash location: Helicopter Rapid.
“I worked out afterwards that there were only nine helicopters in the country at that time and seven of them had been involved in incidents. The government would not approve any more helicopter hire for some years,” Buck recalled.
From then on, the investigation team’s mode of transport was rather more energetic.
“We explored the river with rubber dinghies over a couple of years. They were rescue dinghies from the [English] Royal Air Force. New bottoms were put on them, after much experimentation. We were only the second group to use rubber rafts on the Motu.”
Using their reinforced rubber rafts, the hydroelectric investigation team discovered a “magnificent gorge” at Mangaotane. It was the potential for a dam here — and no option of helicopters — that led to the development of the Otipi Road.
A T Monks of Gisborne were contracted and two or three men took about 18 months to build the road. It was “constructed with a heavy bulldozer by excavating a bench and tipping surplus material over the side. Some large slip faces were created but there were no [environmental] protests from anyone at that time.”
Ultimately, four sites ended up as realistic prospects for dams: (1) up from the Motu river mouth near Houpoto; (2) Mangaotane Gorge, reached by Otipi road; (3) Waitangirua, downstream from Motu Falls; and (4) at the confluence with Mangatutara Stream.
Each site had to have contour surveying. There was also drilling, to determine the depth of the shingle, and to confirm there was rock where a tunnel could potentially be needed.
A camp was established at the Otipi road end, with 12 huts brought in from Opotiki. There was another camp at Waitangirua, where there was a possibility of carrying water through a tunnel. Mangatutara was the last site to be investigated. A road was started from near Rawea Stream, past Takaputahi but this was never finished, because the government reapproved the use of choppers.
A 1959 newspaper report underlined the nationwide significance of the work.
“Present proposals, says an interim report submitted to the Minister of Works, Mr H. Watt, are to harness the river by a series of dams . . . It is expected that the total installation on the river of between 350,000 and 400,000 kilowatts will be possible on normal load operation.”
This 1959 news report suggested that the Houpoto dam could be 350 feet (106m) high. Minister Watt (surely, a most appropriate name) declared, “My information is that the Motu catchment is unusually favourable for development. Some 27 miles [43km] of new roading is being constructed to gain access to prospective dam sites.”
A huge challengeHowever, as the investigations went on, the vastness of the challenge became clear. A 1961 report quotes the engineer in charge of the survey, Mr R. B. Alley — that’s Buck — as saying the territory was like a “miniature Southern Alps”.
He described, “The whole district looks as if it has been taken in a giant fist and crushed as one would crush a sheet of metal foil.”
In 2012, Buck recalled that in one spot at Houpoto, the gravel was 135 feet (41 metres) deep. Even more challenging, the Motu River transforms from lazy summer flows to huge floods.
“A very large proportion of dam building costs would have been in dealing with spillways for the floods.”
By 1963, data collection was finished and ready for analysis. A late-1970s Opotiki Centenary book records that “The Houpoto plans alone covered more than seven square metres of paper”.
But in August 1965, the government’s Power Planning Committee recommended the abandonment of hydroelectric plans, “at least for some time”.
That recommendation wasn’t the end. In the 1970s the popularity of recreational rafting and kayaking grew fast and the Motu was seen as a prime place to pursue the fun. Pressure increased to protect rivers. A campaign led by NZ Canoeing Association and FMC (Federated Mountain Clubs) ultimately led to the 1981 Wild and Scenic Rivers legislation. The Motu became New Zealand’s first ‘Wild and Scenic River’.
Another legislative step came in 1984, when the Motu was the first river to gain a National Water Conservation Order (since 1991, the overarching legislation has been the Resource Management Act).
“But before the government made the [Wild Rivers] decision they wanted to make sure they knew what they were giving away,” Buck said.
That led to a second round of hydroelectric power investigations, together with landscape and recreation studies, and faunal research. Colin Cardiff was involved in this investigation work on the Motu from 1978 to 1980.
“There was a team of about 10. We cleared the Otipi road, and cleared the areas for drilling. Nothing had been done to the road since the 1960s,” Colin said in 2012. The team had a camp at Mangatutara, with workers also staying in Toatoa. Drilling company Longyear was contracted to take bore samples. They had a crew of about five.
Questionable economicsThis second round of investigations confirmed that the economics of harnessing the Motu were questionable.
“At the upper prospective dams, the lake areas were not great. There wasn’t a lot of area to store the water,” Colin said. “You need a big lake storage area — but the [Motu] gorges are tight.”
With legislation in place, the government’s hydroelectric hopes were well and truly over. Around 1983-4, two huts that had been put in at Mangatutara in the late-1970s were helicoptered to the Te Waiti Valley, south of Opotiki, to replace a NZFS (New Zealand Forest Service) six-bunker that had burnt down. The two huts were placed about three metres apart, with a connecting roof and floor. It’s still in service.
The Motu remains one of the North Island’s few true wilderness rivers, its catchment home to a wide range of birds including North Island brown kiwi, New Zealand falcon, kaka, parakeet, blue duck, and North Island weka. More recent years have seen kokako released into a predator- controlled ridge above the lower reaches of the river.
Otipi Road is an adventurer’s dream and the raft trip down to the Motu highway bridge is apparently sensational — with no dam in sight.