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1939. NEW ZEALAND.

DEPARTMENT OF LANDS AND SURVEY. RANGITAIKI LAND DRAINAGE. REPORT FOR THE YEAR ENDED 31st MARCH, 1939, TOGETHER WITH STATEMENTS OF ACCOUNTS

Presented to both Houses of the General Assembly in pursuance of Section 10 of the Rangitaiki Land Drainage Act, 1910.

Sir, — Department of Lands and Survey, Wellington, Ist July, 1939. I have the honour to submit herewith the report of the Chief Drainage Engineer on drainage operations in the Rangitaiki Plains for the year ended 31st March, 1939, pursuant to the provisions of the Rangitaiki Land Drainage Act, 1910. I have, &c., R. G. Macmorran, Under-Secretary for Lands. The Hon. Frank Langstone, Minister of Lands.

REPORT OF THE CHIEF DRAINAGE ENGINEER. Sir, — In accordance with the provisions of the Rangitaiki Land Drainage Act, 1910, I have the honour to submit the report on the work carried out during the year ending 31st March, 1939. The unusual weather conditions of the past season have been responsible for a general decline in farm-production in which the Rangitaiki District has participated. A rainfall of over 15 in. in February, 1938, was followed by a wet autumn and winter on the Rangitaiki Plains. The following summer was unusually dry, and in March, 1939, the rainfall was only half an inch. These extremes of wet and dry weather have affected the pastures and reduced the returns of the settlers. The quantity of butter manufactured by the Rangitaiki Plains Dairy Co., which handles a large portion of the dairy-produce of the district, was 4,256 tons for the fiscal year ending 31st March, 1939, a decrease of 437 tons on the output for last year. The rainfall at Thornton for the period of twelve months, April, 1938, to 31st March, 1939, inclusive, was 51-10 in. Rain fell on 124 days. The wettest month was July, with a fall of 11-13 in. and the driest month was March, when the rainfall was 0-55 in. The average rainfall for the past twenty-one years has been 52-9 in. The programme of maintenance dredging of the main drainage canals which was commenced last year has been continued and a new light drag-line excavator has recently been added to the plant to be employed on this work. Good progress has been made with the work of raising the stop-banks on the right bank of the Tarawera River, but the, unsatisfactory condition of the stop-bank on the left bank of this river has caused anxiety. Two serious breaks in this stop-bank occurred during the winter, and either of these breaks could have been the cause of the river leaving its present course. The construction of the stop-bank on the left side of the river was not part of the Rangitaiki Drainage Scheme, and the bank is not maintained. The bed of the Tarawera River is above the level of the land lying between the river and the western hills, and the soil of the river-bank is easily eroded pumice sand. Originally the overflow during floods was of shallow depth and distributed along several miles of bank. Now when the inadequate stop-bank breaks, flood-water passes through the breach with considerable volume and velocity, and should the efforts to close one of these breaks fail the resulting flooding may cause loss of stock and disorganization of road and rail communication within the district, and it may prove very difficult to return the river to its original course. This matter is of sufficient importance to warrant early attention. Legislation passed last session gives the Minister of Lands power to prohibit the construction of drains where they cause seepage under the Tarawera stop-banks. In this connection for their protection the settlers on the river-banks should communicate with the Drainage Office at Thornton before constructing any drains within a distance of 5 chains from the Tarawera River stop-banks.