MR. O'CONNOR'S REPORT.

Manawatu Herald, Volume II, Issue 276, 28 June 1889, Page 2

MR. O'CONNOR'S REPORT.

Bepout on the entrance to the ManaWATU IUVEIt NEAU FoXTON. To the Hon. the Minister of Public Wokkb. Sir., — In accordance with your instruc tions, I have examined the north of the Manawatu River, and have now the honor to report as follows : — Lfke many of the smaller rivers in New Zealand, the Manawatu Eiver on reaching the sea beach is liable to be diverted out of its direct course 1o the ocean by a sand spit, which treads to a greater or less extent along the coast depending from time to time, on the varying volume .of the river itself, and the prevalence or otherwise of southerly and southwesterly gales. In the case of the Manawatu river the sand spit forms up from the south, and is said to vary in length from about a quarter of a mile to about a liiile.The longer such sand spits are the more the momentum of the river is lost, and consequently, other things being equal, the worse would probably be the channel both in depth and directing, and, as the spit at the mouth of the Manawitu river, is now at about its maximum length the entrance is probably in about its worst stage. When rivers get into that condition they have often been known to change suddenly of themselves, by breaking through the sand spit directly into the sea during a high flood in the river, but the Manawatu river having been for a long time in its present position it has been suggested that it should be assisted in attaining a more direct course by means of artificial w rks. One of the means locally suggested for attaining this end is a sort of wing dam, to be constructed at a point about 20 chains to the south of old flag staff, but I doubt very much if it would have the desired effect. It would in fact in my opinion, probably merely cause a bend in the river, without necessarily driving it through the sand spit at all, and it would also probabty cause the river to deepen, thereby rather tending to fix it in its present course. Another local suggestion is to adopt the class of fascine work at present being tried for river conservation at the mouth of the Wav^anui River, but, even supposing that that chiss of work will serve the purpose intended at Wanganui, it would be quite unsuitable at the Manawatu, as the conditions there are entirely different. In the case of some of the rivers on the West Coast of the Middle Island, where th channels had become very tedious, they , havoibeen straightened in a very inexpensive fanner, by cuffing'" ft' tren oh * through the f,aiirt slips, but, for this to be successful it w&3 'necessary to wait for a high flood in the river, and to open out the trench at doad low water, so that the greatest pos sible amount of fall might be attained, in order to cause the river to scour a channel as rapidly as possible. Even where the circumstances were favourable however, this did not always give satisfactory results, in fact, it sometimes did harm rather than good, as it created two openings in place of one, the force of the river current being thus divided, and the bar being worse. than it would have been with even the most tortuous channel where there was only one opening. The cost of trying such an fexper ment in the case of the M nawatu river might be estimated at about £100, but I would not be. prepared to recommend its being tried, the more especially as the circumstances in this case are not at all favourable, the beach being much wider, and the river less confined, than in the casos where I have known such experiments to be successful. Only two alternatives therefore seem to be left open for selection namely, (1) to be content with the present entrance, which is navigable at ordinary high tides, and daring reasonably good weather, for vessels drawing from six to 7 feet of water ; or (2) to undertake the construction of a training work, of such a character as would lead the river in a direct course right out to the sea beach, and thereafter keep it there. The cost of this latter alternative would be, on the cheapest basis that could be adopted, about £27,000 — This is estimating for timber work such as has been used ;it Hokitika, but it has of course to be borne in mind that such work is not permanent, and that, if the circumstances justified its being maintained, it would have to bo strengthened from time to time, and ultimately replaced, by stone or concrete. As to whether the first cost of the work {. {."27,000 J would be justified by the present conditions of trad,> at Koxton is of course a question for the Government, but in order to enable some opinion to be formed upon it I have attached heit'.o a return «'iowing tho imports and exports at Foxtou wharf for the year ending .'Ust March last, with which the Railway Commissioners have been good euough to supply me. I should also mention that so far as I have been able to ascertain the shipping rate from Wellington to Foxton is about 10s per ton, while the railway freight is, lor merchandise 41s 9d to 58s 2d, for grain 17k od, and for wool 84s 7d per ton. 1 have tho honor to be, Sir Your obedient Servant, C. Y. O'CONNOR. Under Secretary for Public Works.