Lake Levels Assurance

Press, Volume CVI, Issue 31112, 15 July 1966, Page 1

Lake Levels Assurance

(Parliamentary Reporter) WELLINGTON, July 14. The diversion of the Mararoa river into Lake Manapouri is expected to dispose of any suggestion that the waters of Lake Manapouri will have to be raised above present maximum levels for the efficient operation of the huge Manapouri hydro-electric scheme. This has been indicated in the report of the Power Planning Committee tabled in Parliament. The report indicates that

an extra 400 million units of power a year may be available by diverting the Mararoa. It is believed that this will dispose of fears held by those Interested in scenery conservation and by residents and landholders in the area of considerable inundation. The final stages of the programme, not to take place for some years, included the raising of Manapouri levels by about 84 feet. The new assessment Is made possible because the Government consultants in the scheme, the Bechtel Corporation of America, apparently overlooked the potentialities of the Mararoa river, which flows to the east of the : lake.

A major amendment of the original plan, designed against the continuous-load needs of an aluminium industry, is now needed. They will Include a weir on the lower Waiau river, flowing out of Lake Manapouri, to divert the Mararoa river into the lake. This is estimated to cost £3.8 million. The weir will merely hold Manapouri at its normal maximum level. It will be associated with another weir, on the upper Waiau, which links Lakes Te Anau and Manapouri. This will cost £3.3 million. The original plan was to raise Manapouri to the level of Te Anau by means of a high dam, which is not now needed. The new thinking Is that the upper weir will create storage capacity in Te Anau. Between them, the lake, will yield four times the storage capacity of Lake : Taupo. Scenic protection costs, estimated between £2 and £3 million, will be saved. There is also the possibility of including a power station on the upper Waiau river, using water running from Te Anau to Manapouri. To take advantage of the increased storage, the last three of the seven machines to be fitted into the underground powerhouse between Lake Manapouri and Deep Cove will probably be ordered with a capacity of 160 megawatts each, instead of the 100 megawatts planned. This could cost £1.5 million. Even without this increase, Manapouri would have a generating capacity of 4500 million units a year—twice that of Benmore.