WATER FROM WAIRAU.

Auckland Star, Volume LX, Issue 36, 12 February 1929, Page 5

WATER FROM WAIRAU.

AUGMENTING LAKE PUPUKE. HEALTH DEPARTMENT'S CONDEMNATION. SUPPLIES FOR NORTH SHORE. Condemnation by the Health Department of the scheme to impound water from the Waiiau Creek to supplement the Lake Pupukc supply has resulted in the matter being shelved by the North Shore Water Board, pending a fresh election of members next April.

A decision to this effect was made yesterday after the board had considered a report on the matter from Dr. H. Chesson, medical officer of health.

Cost of Scheme, £47,000. The chairman, Mr. K. Aldridge. explained that Dr. Chesson's communication was in reply to a questionnaire submitted by the board after its last meeting, when it had been addressed by Mr. Dufaur, representative of Candy Filters, Limited, who had submitted a scheme for the augmentation of Lake Pupuke by the filtration and chlorination of water from the Waiiau stream. The estimated cost of the proposal was £-17.000, which provided the necessary conduit from the Waiiau to the lake and the cost of filtration and chlorination plants, but did not include any allowance for land on the Wairau watershed. The problem of the lake basin was also outside its scope of reference. This was gradually becoming more acute, for pressure was being brought to bear on the municipal authorities by the owners of the land who paid rates and taxes, but were denied any rights of usage or ownership. The scheme propounded by Mr. Dufaur was to divert the Wairau into the lake during the winter floods, it being, considered that about 300 million gallons of water could thus be annually added to. storage in the natural reservoir of Lake Pupuke.

"The Department does not favour the use of a lowland surface water from an open valley in which farms, vegetable gardens and residences are located, and which is intersected by roads," wrote Dr. Chesson, who intimated that he had discussed all aspects of the Wairau scheme with Dr. R. H. Makgill, advisory medical officer.

"Water from such a stream as the Wairau, which is dependent entirely on the washings of the countryside during heavy rain, must inevitably" be liable to the grossest pollution.

"We are fully aware that it is practicable by modern methods of treatment to convert a polluted water into a reasonably wholesome commodity, and the means suggested in Mr. Dufaur's report may possibly achieve this result, but that cannot be guaranteed by my Department. The whole question depends on the adequacy and efficiency of the plant installed and the staff in charge of it. . ..ffgjgiß Responsibility on Board. "In view of the estimated low cost of the proposal as compared with the Waitakere scheme, my Department does not feel disposed actively to oppose its adoption by the board, but as any approval carries with it a proportion of responsibility, and we cannot accept responsibility for the installation or management of the proposed works, official approval cannot be given, and if the board adopts the scheme it must accept the full responsibility.

"Regarding the question of acquisition of land in the Wairau watershed, it would seem little use acquiring less than the entire watershed, if any is acquired at all. As to the watershed of the lake itself, there can be no departure from the precautions at present required, namely, that no new residences can be erected in the lake basin unless the drainage therefrom can be directly connected with sewers outside the basin, and that an area of approximately four chains around the margin be kept free from human or animal use."

The questions submiitefi to the Health Department were answered, briefly, as follows:—(1) The Department would not agree to the lifting of any of the restrictions on the use of the lake basin or watershed. (2) All water must be sufficiently clarified by filtration or sedimentation, or both, and chlorinated to the extent of being free from B. Coli in 100 c.c. before admission to the lake. (3) Unless the entire watershed of the Wairau was acquired, little would be gained by purchase of any portion other than such as is necessary for the installation and protection of the sterilising and nitration works. (4) The board must take full responsibility for ensuring the safety of the supply.