MANAPOURI SCHEME No High Dam To Fix Lake Levels

Press, Volume CVI, Issue 31222, 21 November 1966, Page 3

MANAPOURI SCHEME No High Dam To Fix Lake Levels

(Neo Zealand Press Association) INVERCARGILL, November 20. The idea of a high dam to equate the levels of Lakes Te Anau and Manapouri for the power project had been rejected, the Minister of Justice (Mr Hanan) said today.

Mr Hanan enlarged on aspects of last week’s variation to the power rights agreement between New Zealand and Comalco Industries, the combine planning to build an aluminium smelter near Bluff.

On Tuesday the Minister of Electricity (Mr Shand) said that a final level for Lake Manapouri, which would need to be raised slightly, could not be set precisely until completion of current site studies on the potential contribution of the Mararoa river.

“The concept of a high dam has now been rejected,” saidMr Hanan. “Instead there will be only a weir on the lower; Waiau river below its confluence with the Mararoa river to ensure that the waters of the Mararoa are turned into power. “The other stage in the project’s development will be control gates on the upper Waiau river near the Te Anau outlet, which would mean that the storage represented by natural levels would be avail-i able at periods of low flow.”! Beauty Safeguards That was in accord with the Government's view from the outset, which was to do everything possible to reconcile the [ views of the Nature Conser-| vation Council and like inter-' ests and hydro-engineers—and I so safeguard the region’s great beauty. Lakes Te Anau and Manapouri could have yielded substantially more power, but current arrangements were designed for optimum economic yield. The building of a high dam would produce more power than now was planned for, but would be a marginal economic proposition.

The power project would be able eventually to deliver 480,000 kw of continuous power

to Comalco for a smelter near Bluff and 200,000 kw at a 60 per cent load factor for the National Grid. However, it was believed that more water could be available than had been estimated, said Mr Hanan. Consideration was being given to increasing the capacity of the generating equipment for the fifth, sixth and seventh units to be installed in the underground powerhouse. Four! units already ordered were | each of IOO.OOOkw capacity. i Gates Alternative Also being considered, as! an alternative to control gates I on the Waiau river at the Te Anau outlet, were control gates further down the river to use the fall in a lowpressure turbine that might yield up to 40,000 kw for the National Grid. Electricity generated above the stated requirements would be available to Comalco, but subject to the State obtaining its 200.000 kw at a 60 per cent load factor, said Mr Hanan.

Under the revised arrangements, Comalco would be en-

titled to 240,000 kw continuous power from Manapouri until July 1, 1973. Thereafter, Comalco would take 300,000 kw (roughly enough for a smelter to produce 150,000 tons of aluminium yearly).

Permanent Right The State had a permanent right to its 200,000 kw at 60 per cent load factor. If the combine ever desired that power, it would have to negotiate. If the 200,000 kw could be spared by the State, the price would be on the basis that there must be no charge on the electricity supply account through the building [of the Manapouri power project, said Mr Hanan. That was perhaps the most j significant change between the new and old agreements between the Government and [Comalco. Previously, the I State had been obliged at a certain stage to make available to Comalco the total power output from Manapouri. “In a nutshell,” said Mr Hanan, “the new agreement makes the great industry possible and at the same time, during the first stage of Comalco’s options, gives the Electricity Department approximately half the total capacity of the project for the National Grid.”