Upper Waitaki Plan Nearly Ready

Press, Volume CIV, Issue 30768, 4 June 1965, Page 3

Upper Waitaki Plan Nearly Ready

(New Zealand Press Association? WELLINGTON, June 3. Investigations into the proposed development of the upper Waitaki river for hydro-electric production are almost complete, and a decision will probably be announced within the next two months. This was announced today bv the Minister of Electricity (Mr Shand).

He said the proposals included a manmade canal running from Lake Tekapo through Lake Pukaki, linking with the Ohau river and entering. Lake Benmore as a single flow. ■Mr Shand said several powerhouses would be built to take advantage of the various differences in elevation along the course of the canal. “The Waitaki river is one of the biggest in New Zealand, is high above sea level for much of Its length and has three large lakes to even out the natural flow and provide means of regulation,” he said. “It is therefore one of the most promising sources of the energy which is required at increasing rate each year,” said Mr Shand. The Minister said Lakes Tekapo, Pukaki and Ohau were drained by rivers of the same names, and these, together with smaller tributaries, combined to form the Waitaki. Mr Shand said below this junction, the river supplied two power stations—Waitaki and Benmore—and a third was being built at Aviemore. CONTROL WORKS “Control works at Pukaki and Tekapo ensure an adequate year-round flow of water to the stations and further storage could be provided by controlling Lake Ohau also,” he said. “At present there is only

one small station in the upper Waitaki valley—at the outlet of Lake Tekapo. opened in 1951,” he said. Mr Shand said if further development of the area was decided on. it would involve progressively combing the flow from the lakes. Releasing copies of a plan showing the recent proposals for development, the Minister emphasised that none of the proposals had been approved by the Government. “At present they are simply a basis for further investigation," he said. Mr Shand said Lake Pukaki would remain at its present level but one line of development which had been under investigation involves raising the level of Lake Pukaki by 100 ft. “This would have made an additional 70 megawatts of power available—but after considering all the factors, it was decided to forego this power,” he said. The Minister said the raising of Lake Ohau—at present uncontrolled—by up to 50ft. would be considered. LAND COVERED He said about 6000 acres—mainly grazing land—would be covered by water and 18 miles of local road would need to be relocated if the plan was adopted. Mr Shand said one homestead would have to be moved. “The fluctuation in lake level—necessary to provide storage in dry periods—would result in wide beaches forming around the lake,” he said. Mr Shand said the ability to store water from summer to winter in Lake Ohau would be of “great value" to the power system and must be “most seriously” considered. Two alternative ideas for development at and below Ohau bridge were shown on the plan. One—which was included in the 1961 pro-

posals—involved a tunnel, the other, a canal. The latter would involve building two stations instead of one between Ohau bridge and Lake Benmore—but if the proposal currently preferred is with modern earth-moving equipment, a canal is easier than a tunnel,” said Mr Shand. The Minister said furthermore, it would entail a much lower dam at Ohau bridge than the one required by the 1961 proposal—with a consequent saving of 7000 acres of grazing land which would have been flooded. “Except possibly on the shores of Lake Ohau. the economic use of existing farm holdings is unlikely to be affected by hydro-electric development,” said Mr Shand. ACCESS PROBLEM “However, there will be severance and access problems created by the canals, and as normal flows down the main rivers will be diverted, it will be necessary to provide alternative water supplies and fence off the old beds.” he said. The Minister emphasised that adequate provision for stock water would be included in any development plan and regular maintenance work to keep open flood channels would also be required. “These and other similar changes will have a profound effect on some holdings,” he said. “I emphasise that for hydro-electric development to be approved, the Government will have to be convinced that it is in fact the most suitable source of power available at the time. “If it is decided to proceed, more discussions will be held with all parties affected to reach agreement on questions of compensation, re-development of water supply services and any other effects arising out of the hydro-electric developments,” said Mr Shand.