WATER-CONSERVATION IN OTAGO.

Mount Ida Chronicle, Volume 29, Issue 1528, 11 February 1899, Page 1

WATER-CONSERVATION IN OTAGO.

During his last visit to the Eweburn dara, in Otago, Mr T. Perham, Engineer for Water-conservation, in company with Mr R. H. Browne, engineer to the Maniototo County Council, examined the Gimmerburn Gorge, in the neighbourhood and to the southward of what is known as the old Garibaldi Diggings, with a view to deciding if water could be conserved in the vicinity to supply these gold workings and be made available to irrigate the farms on that side of the Maniototo Plain. The locality indicated is about 22 miles by road and old dray track from Naseby in a south-westerly direction, situated at -the head of the Gimmerburn Gorge, and nearly on the top of the Rough Ridge Range, which divides the Ida Valley from the Maniototo Plain. The elevation is 1950 ft above the land round and about the plain at the mouth of the gorge. There is already a small reservoir near the gold workings, constructed by the miners, from which water is drawn for sluicing the auriferous ground, but the elevation is so little above the bottom of the work-ing-face that it is not of much use for the purpose, except to float away the tailings. The reservoir is fed by a small snow stream, which runs, together with other tributaries, into what is known as Taylor's Creek, traversing the gorge until it joins the Gimmerburn, which again joins the Wedderburn, on the Maniototo Plain, just before its junction with the Taieri. Payable—in fact, rich ground is reported to have been opened at the Garibaldi, but, as is the case in many similar localities, it was found that, owing to the altitude of the claims and surroundings, a sufficient supply and pressure of water could not be obtained by simple gravitation to work it at a profit. A rough survey is reported to have been run from the Mount Ida Water-race over an intervening saddle, but, as far as could be ascertained, with no satisfactory result. The Garibaldi, by aneroid, would appear to be about 150 ft above the level of the Eweburn dam outlet, which is 2200 ft above spalevel, or 200 ft above Naseby. This conclusively proves that water could not be obtained direct from that source, and probably without great expense near the race iutake. Mr Perham mentions this, as there is an idea among miners that the new Eweburn Reservoir could be made to serve the gold workings. The main object of the examination was to ascertain the feasibleness of constructing a reservoir and furnish an approximate estimate of cost, with a view to providing a water-supply for that portion of the Maniototo Plain in the event of a comprehensive scheme for irrigation being undertaken. As a reservoir site it is a fair one in itself; the extreme elevation is not necessary for the purpose but is objectionable. Although time was limited, on account of the distance from Naseby aud the broken state of the weather, Mr Perham observed enough to him to believe, from the contour of the country, that an equally good site fur irrigation could be found much lower down the gorge, with more water and a much larger gathering ground, and by shortening the distance less costly to get the water out on the plain. The streams feeding the proposed site are mere dribblets, and entirely dependent on the melting snow from the top of the range. It certainly would not be an expensive place to dam, as there is an unlimited supply of slate-schist, but it would uot pay to cut a race out for irrigation, and, as the lied of the proposed reservoir is below the gold workings, would be useless for mining in the locality Under the circumstanc.-s the site is not suitable, and cannot be recommended.

There is another proposed site on what is known as Bread-and-Water Creek, just over the Hough Ridge watershed into the Ida Valley, »">d a convenient low saddle by which the water could be conveyed back and made to serve the land below on the Maniototo Plain side. The catchment area is reported to be far superior lo the Taylor's Creek, but by doing this the water world be diverted from Bread-and-Water Gully (mentioned in a former report on Ida Valley). Here the local miners advocated a dam which would supply part of the German Hill gold workings and irrigation on the eastern side of the Ida Valley, but Mr Perham was of opinion then that a suitable site was not to be got on account of the gorge being so narrow and steep. Time or weather would not permit of this being followed up, and, being fully aware that the settlers in the Ida Valley are, if anything, in want of water as much as or possibly more than, lhos» j n {\ w Maniototo, both for mining and irrigation, it appears that tins water properly belongs to the miners work ing at German Mill and the farmers on the eastern side of Ida Valley. Under the circumstances, Mr Perham does not think that either of thes* sites can be recommended for irrigation on the .Maniototo Plain—the tirsr, at Taylor's Stream, on account of the paucity of water for feeding the- reservoir, and the gro.it expense of rare cutting-out to the plain ; and the latter for the reasons above Mated—namely, robbing <h<» farmers and miners of the Ida Valley of what undoubtedly is thiir natural watersupply. IKBICATION KnSKKVSfH ON TVd WKUDKItItCRX. About four miles from the now railway-station, on the OUig* Central Railway works, and at on elevation of 200 ft above that point-, there is a fine

site for a considerable storage-reser-voir. The valley is very flat, and confined by low and nearby parallel terraces on each side, and the creek runs about four Government sluiceheads down from the gully of Mi. Ida. Both as to elevation and position, it would entirely command the country for irrigating along the southwest side of the plain, by leading a head-race over the. lower slopes of the Rough Ridge range, and the water could be joined lower on the plain to the system from the West Eweburn, but the water from the Eweburn Reservoir would not reach here, as the peculiar contour of the intervening country would not admit of it. A storage, such as this—about 25,250,000 gallons—would not only be of great utility for the neighbourhood of Wedderburn, but would serve the Giinmerbura farms and surrounding country. The dam would be about 10 chains in length and 25ft above the creek level, built of earth, with a piled and clay puddle-core across the creek. There is no indication of rock, but ample evidence of good clay, and from a close examination Mr Perham does not think that any difficulty is to be apprehended in getting in the foundations for a strong dam, costingapproximately froui£4ooo to £5900. About 25 chains higher up the valley, »vith 75ft additional Televation, another good, though smaller, site was selected, which could be utilised as a storage-reservoir, and if at any time found expedient could be tapped to convey water to the tops of the flat and terraces and higher levels round and about the neighbourhood of Wedderburn, or even back to the eastward, and join the Eweburn Dam system. An earthen dam may be built here for about £3OOO. Mr Perham would recommend either or both of these sites. The upper one would contain about 12,000,000 gallons of water. TAIERI RIVER. In considering generally a comprehensive scheme for the whole of the irrigation of Maniototo Plain, reser-voir-sites being few and far beween along the eastern water-shed of the Rough Ridge, south of Gimmerburn (to which the Wedderburn water would reach), it is suggested that an ample and never-failing supply could be obtained from the Upper Taieri at the junction of a tributary locally named the Styx : this may be one of the unnamed creeks on the left bank of the Taieri above the- Loganburn. A series of aneroid levels- and rough traverse of the country would easily determine the contour, and prove if such a scheme be practicable. Then, with the information already-in possession of the department, some idea of a general irrigation scheme may be arrived at.—Mines Record.