CATCHMENT BOARD

Timaru Herald, Volume CLVIII, Issue 23323, 5 October 1945, Page 6

CATCHMENT BOARD

Five-Year Plan Revealed Estimated Expenditure Exceeds £600.000 PROVISION is made for an estimated expenditure of * £607,000 in the five-year plan of the South Canterbury Catchment Board, which has been prepared by the Board’s chief engineer (Mr G. R. Milward). His plan was presented to members of the Board at a meeting in Timaru yesterday so that the Board would be able to frame, in the near future, its future works policy and to create a staff organisation commensurate with the responsibilities involved. Estimates of costs in the report were only approximate, it was emphasised, and merely indicated the size of the various jobs.

It was assumed that the works programme would be spread over five years or more and. although the annual expenditure would vary, it would be probably not less than _ 100.000 in any one year, added. Mr Milward. While the suggested programme might at first seem formidable, all works proposed were necessary. Rainfall this year had teen above the average and may not occur in such intensity again but the increased rate of ruri-off as the result of past erosion in the high country and the accumulations of shingle and growth of willows in the riverbeds made it possible for the rivers to overflow much more readily to-day than ever before. Urgent attention was therefore necessary. It appeared that a Catchment Board rate of Id in the £ was as much as the land could be asked to contribute for river protection, observed the chairman (Dr. P. R. Woodhouse), and efforts would be made to keep the rate below that figure wherever possible. The description of proposed works in each main watershed, beginning at the northern end of the catchment district, was submitted by Mr Milward as follows: Dry Creek Diversion The area of the Dry Creek diversion scheme lies between the Rakaia and Ashburton Rivers and west of Methven. In normal weather the run-off of rainfall is negligible; but when rainfall is intensive, say two or three inches in 24 hours, the water passes over the Rangitata diversion race and is bridged at the Methven-West Coast Road. From this point on there is no definite channel, the flood waters spreading over the countryside causing damage to farms, stock and reading. The effect

of flooding this year has been particularly severe. It has been calculated that the amount of water to be dealt with can be 5000 cubic feet a second, or 1,875,000 gallons a minute. The Public Works Department has recommended a diversion scheme which will cut off this water above the Rangitata diversion race and turn it into the Ashburton River. However, further investigations are necessary before I shall be in a position to make recommendations to the Board. In the meantime, and for the purposes of this report, the estimated cost has been assessed at £BO,OOO.

Ashburton River Considerable protective works have been constructed ' n the Ashburton River in the past, and new works are not contemplated. At the present time the Public Works Department, by arrangement with the Ashburton County Council, is completing the clearing of the riverbed of all growth to provide a fairway for flood waters. The expenditure to date on this particular job is approximately £60,000. The total cost will be in the vicinity of £70,090. of which the special rating area of the County will find approximately one-sixth, the balance being found by the Soil Conservation and Rivers Control Council. The maintenance of the flood fairway is causing some concern, as already’ a second growth of willow, broom, etc., is making its appearance. It is estimated that for some years an annual sum of £35. J will be needed, if the benefit of the capital expenditure is to be retained.. Ash! jrton-Hinds Drainage The Ashburton-Hinds drainage proposal is designed to increase the production of some 70,000 acres of farm lands. The reconstruction of approximately 160 miles of channels and ditches is involved and the cost of the scheme is estimated to be approximately £BO.OOO. This work is particularly urgent. Hinds River Control Flooding, as the result ol overflowing from the Hinds River, has been an increasing menace for some vears. The bed has become overcrowded with willow growth with the usual random deposits of- shingle and bank erosion in places due to obstructions in the stream bed. rhe Public Works Department has previously carried out surveys for the design of a new stop-banking system and for the clearing of the riverbed, but. on account of the heavy cost of the full scheme, it is unlikely that the stopbanking can be done at present. An approximate estimate for the clearing of the stream bed from the mouth to a point 17 miles upstream is gr as

£BOOO. The stop-banking scheme ove) this same length would cost about £34,000. Rangitata River It is not proposed that any riajoi scheme should be initiated on the Rangitata River, but it will be necessary to give attention to the removal of trees and bstructions generally in the fairway of the main river A complete inspection cf this river has not been made, and proposed expenditure will be included later under the heading of “general minor wor-'s.” Orari-Temuka-’ aihi The work on the Orari. Temuka and Waihi Rivers is considered as one project for the two rivers, the Temuka and Waihi being taken as one river. In February of this year flooding from the Temuka-Waihi River covered a wide area, including the Boroughs of Geraldine and Temuka. A small amount of flood waters from the Orari also joined that of the Waihi. but the peak of the flood in the Orari was later than that in the Waihi—otherwise the damage would have been much more disastrous. An approximate estimate for a control scheme is £160,000 and the work should have early priority. Design work and surveying are now in progress by the Board’s officers. Te Moana and Kakahu The stream beds of the Te Moana and Kakahu Rivers are badly blocked with excessive willow growth and accumulated shingle for the most part of their lengths in the low country A detailed inspection should be made later, but it is known that the present stop-banking system needs re locating in places and much of the willow growth removed Suggested expenditure 's given in the meantime as £30.000; but this figure may be wide oi the mar'- when more is known of these rivers. Opihi River From the mouth upstream for abou. 16 miles the bed of the Opihi River is becoming badly obstructed with growth of willows, gorse, etc. Extensive clearing is necessary to establish a fairwav and in all probability an overhaul of the present stop-banking system wil, be required. Serious erosion of farm lands is also taking place near the mouth where major works are indicated Estimating of costs is impossible until a survey has been made and expenditure in this river may reach £75.000 Pareora River The usual trouble of excessive growth in the bed is prevalent in the Pareora River, with the resulting changes in the course of flood flow. In the floods of this year the river attacked the north bank severely between the Mam Trunk Railway and Brassell's Bridge This is the subject of investigation by the Public Works Department at the present time. At a later date the Board should authorise a survey of this river to establish a fairway for the main flow. Future exnenditure on this river may reach £20.000. Otaio and Makikihi The beds of the Otaio and Makikihi Rivers are in a similar condition to that of the Pareora River, but major schemes are not anticipatd in tl neat future. Any expenditure would be included under a “minor works” head ing. VVaihao River A survey of the Waihao River, from the mourn to a point about a milt above the State mgnway is necessary me ouuei, oo on tne sea coast is under repair at the present time by tn. vvainono Drainage doard. It would ap pear mat turther expenditure will bi necessary on this outlet to give satisiactory results from the drainage point o. view. Stop-banking. as lar up as th state highway, also appears durable as there is little treeboard to preven. i.ooa waters from covering the faru lands on both sides of the river. An appropriate estimate for future expenditure in this locality can be lakei at £12.000. Morven Drainage The Morven drainage area is a special one controlled by the Waimatt County council. The existing artificia flood discharge channel is becoming reduced in capacity by shingle deposit; and weed growth. Also in its genera function, the channel is not satisfactory, in mat flood waters which accumulate outside the stop-banks can not enter the channel and have nc immediate getaway. Further invest! oation and survey is indicated and ex penditure in the future is provisionallgiven as approximately £BOOO. General Minor Works Many works of a less extensive naturi are known to be necessary, some o them being urgent. These ii. ludt control of the Opihi River in the vicin ity of Fairlie. a sch ~e for the preven tion of flooding of the Fairlie town ship, control of flood waters of Wai tawa creek, control of south Opuh .-liver at Ashwick Flat, and the Es Valley creek scheme. It is •*' " ’lt ‘ give even an appropriate estimate fothese without preliminary surveys However. I have set down £lOO.OOO t< cover these works. Maintenance We have seen many examples in al oarts of the country of the lack o attention to the clearing of river bed and the cleaning of drains and chan nels. explained Mr Milward The bene fit to the 1-nd fron' river rrre—

*ork or irom drainage work soon disappears if such works are not constantly maintained. It is strongly recommended that the Board include provision for the annual maintenance of all its projects. The amount of maintenance required will vary with each particular job and will depend on factors such as th- weather and the frequency of floods. For the purpose of estimating future liabilities, the annual cost of maintaining works carri-d out under future schemes would be between 2 per cent and 4 per "ent of the capital cost of such schemes. Finance Although the capital value ot the area within .he catchment district is £28,610.456 it is doubtful if more than 15 to 20 pei cent, of the area would receive any direct benefit from the proposed works so lar enumerated. In order to study the general position, let it be assumed that the areas benefiting added together have a total capital value of £5.000.000. continued Mr Milward. An assumed average rate of Id would produce an annual sum of £20.800. To a community already burdened heavily with taxation, an increase of Id in rating would be felt, it being remembered that the county rates (including hospital and harbour rates' are now m the vicinity of lid. It has been estimated that the cost of this would be between 2 per cent and 4 per cent. Taking it at 3 per cent., the annual maintenance costs of schemes outlined would be £lB.OOO <3 per cent, in £6OO 000) which is only £2BOO short of the amount produced by an assumed Id rate From this reasoning it would appear impossible for special rating areas to contribute anything worthwhile to capital expenditure unless subsidies jn maintenance are given A £ for £ subsidy on maintenance would leave a. sum ot say £12.000 tor interest and sinking fund charges which in turn would permit of loans up to £150.000 on reasonably “bort terms. The Soil Conservation and Rivers Control Council is no doubt fully aware of the economics of the position as indicated by their .ntention to provide liberal assistance to the Orari River control scheme Types oi .tate The chairman of the Board 'Dr. Woodhouse' observed that the engineer’s report showed that the Board's expenditure would increase sharply in certain directions and it was therefore desirable to review the future rating position Additional expenditure could be considered under six headings capital maintenance, minor works, plant staff and buildings. To collect funds for the above, the Board could strike three different types of rate special general and administration For he present year the Board had struck onlv one rate—an administration rate of l-25d in the £. which would yield £4754 Dr Woodhouse presented rough estimates of the future requirements of the Board as far as general and administrative ates over the whole district w’ere concerned. Special works rates for both capital and maintenance expenditure would be levied in addition, in those area/; which benefit from the construction of works The estimated rates were: General rate— Minor works amount £6OOO. rate l-20d in £; plant, amount £6OOO. rat- l-20d. Administration rate —Staff, amount £7500, rate l-16d: buddings. etc., amount £lOOO. rate l-120d Total £20.500. rate l-6d “The Board s district is extensive, with a capital value ot more than £28.000.000 so that a small rate yields a considerable sum; but it is realised that land is already rated for county council requirements, for harbour boards and for hospital boards.” concluded Dr. Woodhouse “It appears that a total Catchment Board rate of Id in the •' uf capital value is as much as the land could reasonably be asked to contribute toward works for protection against rivers, as distinct from works for land drainage Efforts will be made to keep the Catchment Board rate for rivers control, even in areas where works are tn progress, below that figure wherever possible.”