LAKE WAIATARUA.

Auckland Star, Volume LIX, Issue 254, 26 October 1928, Page 3

LAKE WAIATARUA.

VALUE TO ONEEUN6A.

AS WATER RESERVE,

The demand by the members of the Onehunga Borough Council, that before Lake Waiatarua (St. John), is drained temporarily to permit of improvements being effected to the surrounding area by the Auckland City authorities, some guarantee should be given that it will not jeopardise the water supply on the Manukau side, is a point well taken. Hochstetter, in his references to the volcanoes of the Auckland isthmus, states that when Mount Wellington forced its way through the mud in an iulet of the harbour, the lava ejected flowed across a valley that ran from the ridge near St. John's College to Onehunga. As the outcome of that Lake Waiatarua came into being. That the valley in question was once heavily timbered, was demonstrated when big drains were cut through the swamp surrounding the lake. Boots of what had evidently been big trees had to be chopped out and these were carted away for firewood. Probably the red hot lava from the new volcano burned off the bush that grew in the valley.

As the reduced area of lake Waiatarua is still about 90 acres and it is well above the level of the springs on the Manukau side from which the water supply for Onehunga is pumped, it is suggested that this area of water, which is there throughout the driest summer, is to some extent a source of supply. Lake Waiatarua at the present time is not ideal drinking water, but percolation through a bed of scoria for a mile or two would filter it. Prior to the lowering of the level of the lake by the Waiatarua Drainage Board, the surplus water in the winter season flooded the low lying area surrounding it, and then flowed down towards Ellerslie, where it disappeared in a hole in the lava bed.

The late Mr. James Stewart, C.E., in a paper published in the transactions of the New Zealand Institute, stated that the ridge behind Mount Eden was the backbone of the volcanic zone, and that the water from the Onehunga Springs on the Manukau side and from the Western Springs on the Waitemata, owed its purity to the fact that it percolated from a mile and a half to two miles through a continuous filter bed of scoria and was also aerated in transit.