Cromwell Gorge ~ Pre-Dam

Clyde Dam ~ The Human Cost

'In all the history of Otago and of New Zealand, in peace and in war, the Clutha proposals must rank as the cruellist and most premeditated. Conceived in departmental ambition, nourished in secrecy and permitted by political indifference for people, the Clutha proposals hardened into unpalatable fact.' ~ Paul Powell, 'Who Killed the Clutha?'

Lowburn's Welcome Home Hotel, built in 1869 and the social focus of the community, was demolished and the area was flooded, '60ft under.'

Harry Perriam, orchardist, Lowburn. His apricot and apple trees were uprooted before his land was flooded.

Shorty Sutherland, and Pythagoras the cat, Lowburn. 'Someone should have shot him (Muldoon) years ago. Me, I wouldn't waste my ammunition. You can tell him that from me.'

Isie Scott, Cromwell. 'I feel our heritage, the land, is being wasted.' She was forced to leave her home on the banks of the Clutha.

Gary Forster, Station Master, and Carl the dog, Cromwell. The Cromwell station was demolished and the line through the gorge to Clyde was pulled up by the end of 1978. (Carl sitting on engine)

Rachael and Fanny Short, Bannockburn. 'I wish they wouldn't change it.'

Harry Gair, Cromwell. 'I've told my nephew (George Gair, Minister of Energy), but he won't take any notice of me.'

Jane and Ted Lawrence, and June the cat, Bannockburn. 'They (the Ministry of Works) say they'll make this place beautiful.'

Charlie Perriam, Lowburn. 'One hundred years of family lost.' The most fertile areas of his land were flooded.

Keith Lake, Northburn. His winter feed land, near the Clutha, was drowned.

Doug Stout, Presbyterian Minister, Cromwell and Lowburn. The Lowburn Valley was flooded. The church was moved to higher ground.

Rabbiters, Pest Destruction Board, Cromwell. The valley behind them was re-shaped and flooded.

These profound, haunting photos recording the human cost of the Clyde dam were taken in May 1978 by highly acclaimed New Zealand photographer Robin Morrison (1944-1993). They are displayed here with the kind permission of Dinah Keir and Jake Morrison, who note that 'The plight of the Clutha was very close to Robin's heart, as were the lives and histories of the inhabitants.'

The Cromwell Gap ~ Pre-Dam



Landslides ~ Gravity Always Wins

In 1973, a Clutha Valley Development Commission was set up to evaluate potential hydro-electric dam sites along the Clutha River. Test drilling in the Cromwell Gorge confirmed what local people already knew, that the gorge was highly unstable. A few years later in 1976, the National Government convened a Clutha Valley Advisory Committee to assess all the available information and to make a decision regarding proposals for high and low dams.

The Advisory Committee acknowledged that there was a serious instability issue, and finally voted to recommend the low dam option (Scheme H), however three members of the Committee who knew the gorge well, voted against any dam at all, referring to the prospect of inevitable landslide issues.

Surprisingly, gorge instability was given little consideration when the high dam option (Scheme F) was chosen. But in 1982 dam workers discovered a faultline directly under the dam and spillways. Investigations revealed that this was a River Channel Fault branching from the main Cairnmuir-Dunstan Fault crossing the gorge some 3kms above the dam. Vast amounts of slurry concrete were pumped into tunnels across the fault called “shear pins” to supposedly lock the fault, even though the fault was 12-15kms deep and such “dental concrete” would be instantly broken in a large earthquake.

It was acknowledged that a fault directly through the dam and spillways warranted some attention. The dam was redesigned around the fault and the "slip-joint" was invented to sit over the fault. The dam was literally built in two "halves."

As time passed, more problems came to light. In April 1989, an intense investigation began into landslide issues, involving an international team of up to 40 geologists. This investigation revealed large numbers of highly permeable loess underlying large areas of broken rock slides, throughout the gorge. It was feared that when the reservoir was raised, the water would permeate through the toes of the slides, triggering landslides into the reservoir, creating waves that could overtop the dam.

Fourteen major slide zones were identified in the Cromwell Gorge, including one beside the dam itself - the Clyde landslide. Another three major slide zones were discovered in the affected part of the Kawarau Gorge, including the Ripponvale landslide. Water was the primary issue, since water entering the permeable loess (fine layers beneath the slides) from above or below, would literally lubricate them, resulting in accelerated movement or a sudden failure.

Cromwell Gorge Landslide Areas

The rate of landslide "creep" was difficult to measure since there was insufficient data available upon which to accurately assess the amount of movement in each slide. The new road cutting above the old road had actually increased the rate of movement in many slides by removing material from the toes of the slides. Geologists soon installed instruments and estimated movements ranging from millimetres to centimetres per week or per year, subject to rain/water and earthquake induced movement. The massive Nile Mile slide, seven kilometres long and 200 metres high, was moving several centimetres per week. The extent of the problem was vast. The international team of geologists described many of the slides as "potentially catastrophic" and "very dangerous." The cost of the proposed stabilisation measures kept going up, but the work began.

Major remedial work was undertaken at nine of the seventeen landslide zones, involving toe buttressing, pumped drainage, gravity drainage, capping to reduce infiltration from above, and the drilling of "grout curtains" to reduce leakage from the reservoir into the toe area of slides.

Cromwell Gorge Landslide Stabilisation Measures

Eighteen drainage tunnels were drilled into the sides of the gorge. From these "drilling stubs" drainage holes were drilled further into the slides. A total of 140kms of drilling was undertaken for drainage, and 6,500 measuring and monitoring instruments were installed.

To install "grout curtains," holes were drilled at regular intervals to varying depths into which concrete and water was pumped under pressure. Many of these holes collapsed during drilling because of the loose nature of the material, and each time this happened, the drillers pumped in concrete and water, and later re-drilled it. This was an extraordinarily time-consuming and expensive exercise.

Buttressing rock was also placed across the base of some slides to provide some frictional resistance. A total of 5 million cubic metres of rock was used in buttressing work.

The Cairnmuir landslide posed a significant challenge, since the upper material was particularly loose and permeable, and riddled with rabbit holes. A network of drainage tunnels combined with buttressing at the toe of the slide failed to stop it moving, so it was eventually decided to pave and terrace the top of the slide to seal out water, creating a bizarre amphitheatre. The rate of movement slowed, but the additional weight means that any increased infiltration could result in an even greater failure.

Cairnmuir Landslide during stabilisation work


Cairnmuir Landslide ~ Aerial View

In the end, the investigation and stabilisation work cost a staggering $936 million. Work on the Nine-Mile landslide alone, reportedly cost $60 million.

Landslide "creep" has been reduced, but monitoring indicates the continuing potential for slide zone failure. Monitoring has shown that movement of a known "active" part of the Brewery Creek landslide is triggered when the water level exceeds a critical threshold in a key piezometer (instrument for measuring hydraulic pressure). Records also show that movement of part of the Ripponvale landslide increases following prolonged rainfall, and that it is highly sensitive. Data indicates that the rate of movement of the Ripponvale landslide increases when the cumulative rainfall during a period of 3 to 4 months exceeds a total of about 300 mm. It has been suggested, alarmingly, that a failure of the seven kilometre long Nile Mile landslide could form a debris dam causing a catastrophic wave event, followed by widespread inundation in the Cromwell area.

Despite all that has been done, and the mind-boggling cost, major landslide zones in the Cromwell Gorge are still prone to failure under the impetus of heavy rain events, and of course earthquakes. The landslide risk has not been removed, and no one knows when the next major landslide will occur.

Fruitgrower's Road ~ Pre-Dam

Here's a view looking up the Cromwell Gorge from Clyde, along Fruitgrower's Road, before construction work on the Clyde dam carved up this landscape, eventually flooding both the roads visible in this scene.

Lost Orchards and Farmland

Cromwell Gorge orchard, Fruitgrower's Road, before the Clyde dam

Before the Clyde dam, the Cromwell Gorge produced some of New Zealand's best fruit. The reservoir behind the Clyde dam flooded a total of 2,300 hectares of productive land, including 12 large orchards on the river terraces along both sides of the Cromwell Gorge, 5 orchards at Lowburn, and fertile farmlands on both sides of the Clutha River in the Lowburn area.

The orchards in the Cromwell Gorge and a few orchards at Lowburn had frost-free micro-climates producing fruit early, earning good prices over the Christmas and New Year period. The Government, however, maintained that profitable late maturing fruit could be grown in the Earnscleugh area with a new irrigation scheme from the Clyde dam. They claimed that late maturing nectarines and peaches could realise $50,000 to $60,000 per hectare per year. Growers were sceptical, and MAF (Ministry of Agriculture and Fisheries) publicly said that this was unlikely.

The Clyde dam proceeded in the face of numerous objections, and the much touted irrigation scheme eventually only delivered limited water from the top of the Clyde dam to Earnscleugh, to help maintain flows in the Fraser River. The late nectarines and peaches never realised the projected returns.

Meanwhile, some of the most fertile farmland in Central Otago, bordering the Clutha River at Lowburn, disappeared under the Dunstan reservoir.

Clutha River, Lowburn, before the Clyde dam

The Cromwell Gorge Railway

'The Dunstan (Cromwell) Gorge is a scene such as Salvator Rosa would have loved to paint; and if it were brought within the reach of cheap steamboats or Parlimentary trains, it would be thronged with artistic visitors, and vulgarised by gaping tourists.' ~ Vincent Pyke, Chapter 3, 'The Story of Wild Will Enderby', 1873.

As early as 1873 it was apparent to Vincent Pyke and the residents of Central Otago that a railway might one day reach inland as far as Cromwell, providing not only a freight and passenger service, but also bringing tourists to admire the dramatic landscapes of the region.

Construction of the Otago Central Railway began on June 7, 1879, when Vincent Pyke turned the first sod at Wingatui, 12kms south of Dunedin. Progress was slow, however, and within a year the line had become a victim of the economic depression of the1880s. A decade passed before the first section to Hindon (27kms) was opened in 1889. Over the years, scores of labourers, stonemasons, blacksmiths and engineers worked through frozen winters and scorching summers to push the line further inland, reaching Middlemarch (64kms) in 1891, Ranfurly (123.5kms) in 1898, Omakau (178.5kms) in 1904, Alexandra (207kms) in 1906, and Clyde (216kms) in 1907. Here work stopped until 1914 after which the last 20km section of line through the Cromwell Gorge to Cromwell (236kms) was finally completed in 1921.

Cromwell Station, by Albert Percy Godber, 1930.

The Cromwell Station was opened in July 1921. It consisted of a station building, a 60ft x 30ft goods-shed, a loading bank, and cattle / sheep loading yards. Since it was a terminal station it also had an engine-shed, turntable and coal and watering facilities. The station sidings could accommodate nearly 100 wagons.

Wool bales from the Criffel run arriving at the Cromwell Station, circa mid-1920's.

In 1942 the station burnt down and a new station was built. The fire was later attributed to leaking and self combusting science chemicals awaiting delivery to the local school. The station was closed in 1976, the same year that the site for the Clyde dam was chosen. The 20km section of line, through the gorge from Clyde to Cromwell, was closed in 1980. Officially, the closures were blamed on declining activity, but it's clear that the government did not want the line to remain open because of the dam project, and that this hastened its demise.

Various steam locomotives serviced the Cromwell Station, including a 37 ton E class, a 30 ton R class, the 57 ton UB class in the 1920s and 1930s, the 78 ton A class, the 72 ton Q class in the 1940s, and the 87 ton Ab class which was used on the line from 1936. The last regular steam-hauled train left Cromwell on 23 February, 1968.

Cromwell Station with Ab663, by Stephen Buck, 1958.

Diesel-electric locomotives were introduced on the Otago Central Railway in February 1957 with the Dh class running as far as Clyde. They were re-classed as Dg in 1968 and withdrawn by 1983. These Dh/Dg class engines were too heavy to run on the lighter rails of the Cromwell Gorge. However, when the much lighter Dj class diesel locomotives (with 10.3 tonne axle loading) were introduced on 26 February, 1968, they were allowed to run through to Cromwell, replacing the remaining Ab class steam engines which were withdrawn. Di class diesels also worked on the Otago Central Railway from 1978 to 1984 but being fewer in number were seen less often than the Dj class engines, which were the mainstay of the line until its closure in 1990.

Passenger services began on the Otago Central Railway in 1900 and were replaced with mixed trains in 1917, with passenger trains only running during the busier holiday periods. The passenger trains were reinstated in 1936. One of these trains was involved in the Hyde rail tragedy in 1943. Passenger trains were again replaced with mixed trains in 1951, and in turn replaced with Vulcan Railcars in 1956. The railcar initially ran to Cromwell, but was cut back to Alexandra in May of 1958. Railcars ceased running on 25 April 1976.

Cromwell Gorge Railway in winter, by Robin Morrison, 1979.

The Otago Central Railway played a major role in the development of the region transporting thousands of tons of livestock, wool bales and fruit to market. One of the line’s busiest years was 1960 when almost 500,000 sheep left Central Otago in double-decker sheep wagons heading to sale yards and freezing works. In a good year up to 4,000 tons of fruit would leave Central Otago orchards by rail for destinations as far as Auckland. The railway also served as a supply line for equipment, food and merchandise, mail and newspapers, and excursion trains ran for the Blossom Festival and at Easter.

Ab663 in the Cromwell Gorge, 1962.

Although other branch lines in the South Island declined in the 1980s, the line to Clyde was kept open to transport construction materials such as cement and steel to the Clyde dam project. When the dam was completed, the line had little other traffic and the section from Middlemarch to Clyde was closed by the New Zealand Railways Corporation on 30 April, 1990.

The line beyond Middlemarch was lifted during 1991, and the track-bed as far as Clyde was handed over to the Department of Conservation in 1993, becoming the Otago Central Rail Trail, now a major tourist attraction.

In 1995, the Otago Excursion Train Trust, in partnership with the Dunedin City Council, formed Taieri Gorge Railway Limited, purchasing the line to Middlemarch along with some locomotives. The 60km Taieri Gorge Railway has become one of Otago’s premier tourist attractions, operated with the assistance of the Trust’s volunteer members.

Sadly, the tourism potential of the Cromwell Gorge railway was never realized.