IRRIGATION IN GALLOWAY DISTRICT

Otago Daily Times, Issue 27541, 8 November 1950, Page 10

IRRIGATION IN GALLOWAY DISTRICT

Irrigation In Central Otago (3)

NEW DEVELOPMENT

Maniototo And Upper Clutha MAJOR SCHEMES PROPOSED Irrigation in New Zealand is largely peculiar to Central Otago and parts of Canterbury. It has been more extensively developed in Central Otago, and successive Governments have realised the necessity for additional schemes in the national interest. The localities in which irrigation schemes already operate are in the districts of Arrow (3241 acres), Tarras (2698), Ardgour (1322), Last Chance, below Earnscleugh, near the Clutha River (2818), Earnscleugh (2065), Manuherikia (4769), ' Galloway (2651), Omakau > (approximately 9000), Hawkdun (8813), Ida Valley (12,358), and Teviot, along the Clutha (3900). Proposals have been made to irrigate an additional 14,000 acres in the Upper Clutha district between Lake Hawea and Cromwell along the of the Clutha River, and 86,000 acres in the Maniototo area fi;om Ranfurly past Patearoa towards Paerau.

The proposed irrigation of the Upper Clutha country is dependent to a large extent on electric power being made available, from the new Coal Creek hydro-electric scheme for pumping water. The use of pumps is regarded by the Ministry of Works as an economic proposition, provided that the areas to be served with water for irrigation purposes would themselves be economic when supplied. The proposed Maniototo scheme would raise the productive capacity of 86.000 acres of irrigable land considerably. It is proposed that a dam should be constructed at the Styx. This would create a lake which would flood some farm land, but the eventual benefit to the whole Maniototo area would be still greater by the use of marshy, marginal land for conserving water. Final plans are now being taken out by the Ministry of Works for the raising of Fraser’s dam, which not only serves the Earnscleugh district with water for irrigation, but is also used for storing water for hydro-elec-tric purposes. The dam is to be raised 15 feet, and machinery is now on hand for the generation -of power. With power for pumping irrigation water supplied either from the Fraser’s dam scheme or from Coal Creek, it would be possible for another 1000 acres of land in the Earnscleugh district to be supplied with water. The land in this district is used largely for fruit growing. Farmers, however, are concerned that supplies of water up to 15 heads a day may be supplied to the Earnscleugh gold dredge, which, they claim, is destroying land suitable for fruit farming, and is leaving bare tailings. Although the fruitgrowers are receiving sufficient supplies of water for irrigation purposes, they feel sure that supplies for dredging operations may have an adverse effect upon the position.

Lake Onslow, which provides irrigation water for the Teviot area, by about three feet to bring into the existing scheme about 2000 acres around Roxburgh and Miller’s Flat. This would provide additional water storage for either new areas or those at present served. Additional conservation was proposed in the Dunstan area some years ago by the construction, of a dam about 12 miles from the junction of the creek with the Manuherikia. This was surveyed, but the project lapsed. When the Ida Valley scheme operated in 1927, it served 14.000 acres of land in the valley and in Galloway, and only the Manorburn was used. The Irrigation Commission reduced the area to 13,653 acres in 1928. In 1931, the Poolburn Dam was completed, and last year the area served was 14,277 acres. To bring Hope’s Creek into this scheme a tunnel of about two miles would be required, with a dam of about 100 ft on Hope’s Creek. The effect of the linking of Hope’s Creek' with the Manorburn Dam would be to link a catchment area of satisfactory rainfall to one of comparatively small annual rainfall. Farmers in the district, however, subscribe to the proposal that before any major development work is done in this area, the practicability of raising the Manuherikia Falls Dam to benefit a much greater total area should be thoroughly investigated by the Government with a view to ensuring adequate supplies, removing injustices to the 'lisers of water from smaller races in the Vincent County who are not now receiving an assured supply of water, and bringing into increased production areas not now served with water. Summarised, the claims of farmers in this area are: (a) Irrigation without adequate conservation is wrong; <b) the raising of the Falls Dam is practicable, and would give a greater assurance “of adequate supplies of water at all times than there is at present; (c) irrigation development is in the national interest and should be carried out in times of national prosperity; (d) farmers would be prepared to pay higher rates for irrigation water provided that supplies were assured: and (e) irrigation in Central Otago trebles the productive capacity of the land. Farmers deprived of adequate supplies of water for irrigation purposes when they need it most in the summer months have a number of courses open to them. If‘they have Crown leasehold land and some freehold, their natural inclination would be to divert the whole of their supplies of water on to their freeholds, with disastrous results to the other land. If their holdings are all Crown leasehold, as is the case for the most part, they may decide that long-term planning is not to their financial advantage. Instead of farming the land, they may "mine” it with a view to obtaining the best possible results in the term of their tenure. This would leave the land in such a state that it would be uneconomic for farmers succeeding them to endeavour to bring it back into full production by long-term,-, intelligent farming methods. In effect, the Government has more than a stake in costly irrigation schemes; it has under its control a natural heritage in land which, can be developed only with assured supplies of water.

Some new development of the present Chatto Creek irrigation scheme is possible where the creek joins the Manuherikia Riyer. Surveys have been carried out with a view to the provision of a new weir across the creek to enable water to be pumped across the river to the Dip Creek and Galloway areas, where about 1200 acres of land not now fully supplied with water for irrigation purposes could be improved. At the Oturehua end of the Ida Valley the country has not been fully irrigated but the raising of the Manuherikia Falls dam would probably contribute towards a solution to the difficulties of the farmers in the area It has been suggested that overflow water from the dam could be used for generating hydro-electric power, to be used in turn for pumping water over the Home Hills saddle to the Oturehua dam. This is probably impracticable, as the overflow would not be a stable volume of water such as would be required for the operation of a successful power scheme, but power could be used from Coal Creek for this purpose The Oturehua dam cannot be raised successfully qwing to the close proximity of the railway station, but water from the Manuherikia in an assured supply would serve to keep the level of the dam constant during the summer months when water for irrigation is vital. Proposals have been put forward for the raising of the level of the dam at