LAKE COLERIDGE LEVEL

Press, Volume LXXXIII, Issue 25205, 9 June 1947, Page 6

LAKE COLERIDGE LEVEL

1930 Record Figure Approached DIFFERENCE ONLY FOUR FEET Lake Coleridge is now only four feet above the record low level reached in September, 1930, and, with normal weather, no great flow into the lake can be expected for another seven weeks at least. At the 1930 low level, a whirlpool formed ominously over the intake, showing that the load on the generators would have to be reduced and that the point where the station had to close down might not be far away. The demand would normally go on increasing until the end of this month, so that the State Hydro-electric Department is faced not only with the need to reduce present consumption to check the foot-a-week fall in tne level of the lake, but also with the task of holding down the seasonal increase for the same reason.

The generating capacity of the station has not been greatly affected so far but, as the lake level falls, the load on the generators mpst be lessened. If there is not a great deal of water above the intake, there is a danger that turbines turning at high speed will suck in air through the vortex of a whirlpool, like that formed on a small scale in a bath when the last bit of water is emptying. This would cause considerable damage to the generators and have effects over the whole of the South Island grid. The load had to be reduced in 1930 and, had the level of the lake fallen further, the load would have been cut back still more. The level then was 1658.5 feet, compared with 1662.6 feet last Friday. The saving of units will save stored water and, as well as lengthening the period during which Lake Coleridge can maintain supply at all, it will make a greater peak load capacity possible for a longer time. With fine, warm weather last week, then* were no unannounced peak load cuts, but a change in the weather might again overtax the system, as it did on May 30 last. Supply authorities in their power rationing schemes are doing their best to take the load off the peak hours, but the seasonal demand factor is operating in the opposite direction.