The Press TUESDAY, JULY 19, 1966. Reshaping Manapouri Power Scheme

Press, Volume CVI, Issue 31115, 19 July 1966, Page 16

The Press TUESDAY, JULY 19, 1966. Reshaping Manapouri Power Scheme

The alternative long-term development of the Manapouri and Te Anau power scheme implies a major change in the character of the project. The shift in emphasis is from planning for higher continuous load demands by an aluminium industry to planning for greater use of the scheme for public power consumption. A Government decision to follow the alternative plan mentioned in the annual report of the Planning Committee on Electric Power Development would be good news for those who deplore the proposal ultimately to raise Lake Manapouri nearly 90ft, almost to the level of Lake Te Anau. The proposals which are now being negotiated with the Consolidated Zinc Proprietary, Ltd., also involve considerable capital savings by deferring the building of three power stations on the upper Waitaki river, which must be contingent on the company agreeing to the Electricity Department drawing more heavily on Manapouri power up to 1975. The increased Government share of Manapouri power would be obtained at a capital cost of £ll million compared with a capital cost of £55 million for the three stations in the Waitaki system. By building a weir on the lower Waiau river below its junction with the Mararoa river—high enough to reverse the flow of the lower Waiau but not to raise the lake level—the waters of the Mararoa would be added to the flow to the Manapouri generators. The loss of storage behind the high dam at the outlet of Lake Manapouri would be compensated to some extent by larger generators to make use of the increased water flow. The storage provided by the natural variation in the level of Lake Te Anau—about 20ft—was included in the calculations of the original scheme; and the possibility of drawing on the Mararoa river was. of course, foreseen in the Manapouri-Te Anau Development Act of 1963. Although bound by its agreement with the company, the Government is clearly perturbed by the prospect of heavy capital expenditure on power stations that would not be urgently needed in the event of Consolidated Zinc’s not exploiting the reserve capacity of the Manapouri scheme. The company must decide whether to exercise its option within a little more than two years. An amendment to the agreement in favour of more extensive use by the State of the reserve capacity has become a reasonable objective for the Government This does not deny the company a substantial supply of power with which to start its industry. It does curtail early expansion. Holding the reserve capacity for this possible expansion has become an expensive gamble.