Clyde Dam

Clyde Dam
Clyde Dam from the east, looking west
Location of Clyde Dam in New Zealand
Location	Clyde, Otago, New Zealand
Coordinates	45°10′46″S 169°18′25″E / 45.179314°S 169.306955°E / -45.179314; 169.306955Coordinates: 45°10′46″S 169°18′25″E / 45.179314°S 169.306955°E / -45.179314; 169.306955
Dam and spillways
Type of dam	Concrete gravity dam
Impounds	Clutha River
Height	100 m (330 ft)
Length	490 m (1,610 ft)
Width (crest)	10 m (33 ft)
Width (base)	70 m (230 ft)
Reservoir
Creates	Lake Dunstan
Surface area	26 km2 (10 sq mi)
Power station
Operator(s)	Contact Energy
Commission date	1992
Turbines	4× 108 MW (145,000 hp) Francis turbines
Installed capacity	464 MW
Annual generation	2,100 GWh

The Clyde Dam, New Zealand's third largesthydroelectric dam, is built on the Clutha River near the town of Clyde. It is owned and operated by Contact Energy.

There was considerable controversy when the dam was planned because it would flood many houses and orchards upstream at Cromwell, as well as the scenic Cromwell Gorge, which was a highlight of the then young but growing New Zealand tourism industry. Construction also required replacement of a stretch of highway and the closure of the Otago Central Railway beyond Clyde, though materials for the dam would provide significant traffic for the rest of the line which was experiencing a drop in freight tonnage. To mitigate these problems, the Kirk Labour government decided a low dam should be built at Clyde. This decision was overturned by the following National government, who preferred a high dam.

There was also debate about whether the dam was needed. National's support for a controversial aluminium smelter at Aramoana, another of Prime Minister Sir Rob Muldoon's Think Big projects of the late 1970s and early 1980s, was one justification propounded for the dam. An initial grant of water rights for the dam was overturned by the High Court following an appeal by landowners. National overturned this decision, after bargaining for the support of Social Credit (who had initially opposed a high dam), in the Clutha Development (Clyde Dam) Empowering Act 1982. The Act was later repealed by the following National government on 1 October 1991, when it was superseded by the Resource Management Act 1991.

The dam was constructed between 1982 and 1993. Filling it was done in four controlled stages beginning in April 1992, and completed the following year, creating Lake Dunstan. The power station has a capacity of four 120 MVA (116 MW) francis turbines (for a total of 464 MW), but was only allowed to run 432 MW due to resource consent conditions. The dam is built such that two further penstocks and turbines can be installed, but if they were installed there will not be enough water to keep them running.. The resource consent was changed in 2005 to allow the full 464 MW to be produced.