IRRIGATING CENTRAL OTAGO.

Evening Star, Issue 14574, 24 May 1911, Page 9

IRRIGATING CENTRAL OTAGO.

THE IDA VALLEY THEME. NOW IN HAND. Whilst the Hon. R. M’Kenzie was in Lawrence he told our reporter something about the scheme for irrigating and peopling a large slice of Central Otago now arid, and the Minister asked Mr Furkert to supply particulars. In this way we are able to tell oar readers something of interest about this important undertaking. Mr Fnrkert saki : The area, on winch the Government will probably make it commencement with irrigation is in Ida Valiev. This area, though known as Ida Valley, is not in the valley of the Idabum, but really in the valley of the Poolbom, from above the Moa Creek School down to the vicinity of the Poolburii viaduct. Thk area may for convenience be divided into three zones. With each a little different method of water supply will be adopted. Primarily the water will be supplied from the Manorbnrn and Tool burn streams. The rainfall at the head of these streams is considerably greater than on the valleys below, and it will be conserved by means of several large dams, probably four in all, one of which will be really the increasing of an existing dam. Some years ago the Bonanza Sluicing Company partially constructed a dam designed by Mr Leslie Reynolds, It was not finished. The Government propose to enlarge and raise this dam, and also build another one in a narrow gorge three and three-quarter miles below it. There will also be a dam in the Poolburii, a short distance above where the old Dunsuui road crosses it near the summit of Rough Ridge, at a place locally known as Drunken Woman’s Gully. Then there will be another dam something over a mile above the one at Drunken Woman’s Gully. In the case of the Manorburn water it •will be conveyed by’enlarging the old Bonanza race for a distance of about seven miles. From there the water will be carried in a new race to a point where a fall of considerably over 200 ft is obtainable in the Mai Creek.

At this point it is proposed to erect a hydraulic plant for the general;,in of electrical energy, which will be transmitted and used in connection with pumping for zones 2 and 3. !

The tail water from this power station, after running; down the Moa Creek for some miles, will be stopped by a diverting weir, from which point it will be carried by races, one on each side of the valley, these races running, with a small fall, in such a position as to enclose between them the greater part of the irrigable area in. zone No. 1.

From these main races the distributor}races will be carried on such lines as will enable all the ground suitable for irrigation to be commanded.

This refers to zone No. 1, approximately an area of 15.000 acres. It should be here mentioned that the water from the Poolbum dams after beintr conserved during the winter will be released during the irrigative season, and will flow into one of the before-mentioned races, thus supplementing* the flow therefrom, and being responsible for something over one-third of the above area.

It will be readily realised that when some hundreds of millions of cubic feet of water are launched on zone No. 1 the whole of this will not be absorbed by irrigation operations, but that there will be caused a considerable flow in the natural creeks. It is proposed to catch this water at the point where the Poolburn, Moa, Dovedale, Maori, and other creeks converge, and lift it by means of electrically-operated pumps supplied with power from the station above referred to, and it will be forced jto a sufficient height to carry it on by means of races into a small fall, from which a system of distributories will run as in the case of zone No. 1.

As the land in the vicinity of this proposed pumping station is fairly flat, a high lift will not be necessary, and only a small proportion of the available power will be used at this point. The remainder of the power will be transmitted to a point on the Mainiherikia River, closely adjacent to where it is joined by the Poolbum. Here a more extensive pumping plant will be installed, and the water will be forced to a height (approximately between 300 ft and* 350 ft) from which it can be carried alone: the flatter slopes above the Poolburn Gorge and run along the Ida Valley side of the Raggedy Ridge almost back to the locality known as Blacks No. 3. This race with its attendant distributories will serve the land lying between the foot of the hills and the Poolburn stream.

The surveyors are now out, and have been working for some time before the distributorice can be set out. It is necessary to have levels taken all over the area to be irrigated. From the levels thus obtained a series of contour lines are constructed on plans which enable the fall of the country to be seen at a glance in every direction. The greater part of this work is done on zone No. ], and the distributories are now beinc set out.

“ And when shall be see the navvies at ■work V*

Mr Turk ext replied that the chances were that the work of making the dams would be started in the spring.