THE 'Mighty Clutha' forms the heart of one of the world’s most unique waterways. It traverses the dramatic semi-desert landscape of Central Otago, in the South Island of New Zealand, but the most spectacular river gorges, and much more, have been destroyed ... by dams. This is the unofficial story of the Clutha Mata-Au River and its stolen treasures. It is a story steeped in bitterness, shame, destruction, and sadness.

Roxburgh Dam Statistics

- Site chosen: 1947
- Construction: 1948-1962
- Commissioned: 1956-1962
- Type of Dam: Concrete gravity dam (largest in NZ)
- Dam Height: 76 metres
- Net Head of Water: 46 metres
- Width at Base: 61 metres
- Width at Top: 10.7 metres
- Length at Top: 358 metres
- Penstocks: 8
- Spillways: 3 with upgraded gates
- Sluices: 2 low level gates (non-functional?)
- Planned Capacity: 320MW
- Installed Capacity: 320MW
- Current Capacity: 320MW
- Turbines: 8x Francis fixed-blade turbines connected to 40MW salient pole generators
- Total Concrete Poured: Approx. half million cubic metres (over 1,422,466 tonnes)
- Total Steel used: Unknown
- Weight of Dam: 1.5 million tonnes
- Annual Energy Generated: Averages 1,650GWh
- Reservoir Size: 6 square kilometres (one estimate 4.5 square kilometres)
- Reservoir Fill Time: reportedly filled over several days
- Major Landslide Zones: reportedly 2 known large landslide areas
- Stabilisation Tunnels: Nil
- Measuring and Monitoring Instruments: Nil originally, now?
- Drainage Mitigation: Nil
- Landslide Buttressing: Nil
- Land Flooded: Unknown, but minimal.
- Operational Range of Reservoir: 1.85 metres
- Reservoir Storage Capacity: Described as "Not much"


TOTAL Project Cost: Reportedly NZ£17,000,000 (exact cost is unavailable or unknown)


Operation: The reservoir does not have much storage capacity, so the Roxburgh dam, like the Clyde dam, operates mainly on a ‘run of the river’ basis, with the average flow past the dam reflecting the natural flow of the Clutha and Kawarau Rivers, and the Clyde dam. The expected variation of the reservoir is about 1.8 metres, compared to the Clyde dam’s range of about 50cms. When inflows are low, storage at Lake Hawea is drawn down to compensate.


By Molyneux Rush  

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About This Site

Cromwell before the Clyde dam was set to become a tourism icon. Blessed with a dramatic location, numerous historic buildings and a spectacular bridge overlooking the famous Cromwell Gap, its potential was obvious, until ... "think big."



The Roxburgh Gorge, too, with its many amazing rapids ~ the largest whitewater in New Zealand, had vast tourism potential, offering Alexandra and Roxburgh a booming industry focused on high volume whitewater kayaking, rafting and dory adventures unlike anything else in New Zealand.



The Clutha Mata-Au, before the Roxburgh and Clyde dams, possessed many natural treasures in the form of extraordinary river features and rapids.



This website tells the story of those stolen treasures, and records the bitter fight of ordinary New Zealanders pitted against arrogant government technocrats and politicians who considered the Clutha River ripe for exploitation at any cost.



Finally, the rising waters behind the Clyde dam submerged the historic main street of old Cromwell, the Cromwell Gorge including the famous Cromwell Junction, the Lower Kawarau Gorge including Sargood's Rapid (rated the best whitewater rapid in the world), the Cromwell Gap Rapid, the Lowburn area, and numerous orchards and homes. A total of 2300 hectares of productive land disappeared.



This website is a tribute to the Mighty Clutha, and to the many dedicated people who have fought, over decades, to protect its natural treasures.



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