REPORT ON PETITION OF LANDOWNERS IN THE TAIERI COUNTY, TOGETHER WITH MINUTES OF EVIDENCE.

Appendix to the Journals of the House of Representatives, 1877 Session I, I-02b

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1877. NEW ZEALAND.

REPORT ON PETITION OF LANDOWNERS IN THE TAIERI COUNTY, TOGETHER WITH MINUTES OF EVIDENCE.

Report brought up 7th August, and ordered to be printed. REPORT. The petitioners state that the action of the Taieri River Conservators in making an embankment on the west bank of the river has had the effect of raising the flood waters of the river beyond ordinary height, and materially damaging the petitioners' property on the east bank, and they pray that no subsidies be granted to the Taieri River Conservators as at present constituted. I am directed to report that, in the opinion of the Committee, the matter is a question for the consideration of the Government, as it involves a difficult engineering question, and should only be dealt with after careful inquiry and on a comprehensive plan, especially as a considerable sum of public money has been expended on river works, the utility of which appears to be doubtful. T. Kellt, 7th August, 1877. Chairman.

MINUTES OF EVIDENCE. The Hon. D. Reid examined. 1. The Chairman.'] Mr. Reid, you have read this petition? —Yes. 2. Are you acquainted with the locality referred to ? —Yes; very well. 3. Would you kindly state to the Committee your view ou the matter?— Well, there is no doubt that the embankment on one side of the river will raise the water on the properties on the other side of the river to some extent, if they do not take steps to protect themselves. 4. Can they not take steps under the Acts referred to ?—Yes, if they bring their land under the operations of the Act. If they could get all the people to go into it they have a considerable area, though it is not so great as on the west side ; but the embankment would not require to be so high, and there is not so large a force of water. It requires the voluntary action of a certain number of the owners to enable them to come under the Act, and all do not seem disposed to come under it. 5. That is, I suppose, because only a few would be affected by the floods ?—Yes. Those furthest back would not be affected very much by the floods ; the worst that could happen being the overflow of a little backwater, the currents not coming near them. 6. Do you think the action of the Conservators will have the effect of increasing the depth of the floods on the properties of those who complain ? —-Yes ; I think it would ; indeed it has done so. It is really a matter, however, upon which I do not like to give an opinion, as there are some very strong opinions amongst the people in the locality ; but I think, where owners are prepared to spend money to protect their property, unless it can be shown that they are doing serious injury to others, they should not be interfered with. I cannot see that any very serious injury will be done here. It will of course increase the height of the water if the embankments are made large enough, but it will not materially affect the currents —merely the depth of the backwater. 7. What length of embankments is thero made under this Act on the west bank? —I dare say two or three miles. 8. Already constructed ?—Yes; there had been. But it has been partly washed away by the recent flood. 9. Mr. Burns.] From your knowledge of the locality, do you think a flood would do more harm on the west bank than on the east bank, taking into consideration the amount of water thrown up as flood-stream on the west bank ?—Yes. The last flood was higher than many of its predecessors, but Ido not know that there was any more water than on previous occasions. The water was dammed in to a certain extent by the railway works. I attributed the height of the flood partly to that cause. I—l. 2b.

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10. It had less facilities for discharge than formerly ?—Yes. 11. Do you think the water at Scrogg's Creek affects the water at Silver Stream ?—Yes. 12 How ? —By damming it up. 13. Has it ever been brought under your notice that a scheme was proposed by Mr. J. T. Thomson with regard to that river ? —Yes. 14. Do you think if that plan were carried out it might to a large extent prevent so much damage being done ?—lt would prevent damage being done to some properties, and would itself damage others. Some properties would be benefited, while others would be utterly ruined. 15. Have you ever given the matter any serious consideration, with a view to a more general plan for dealing with that river ? —I think there might be a modification of Mr. Thomson's plan which might do a great deal of good generally ; but it would do some damage at the Waipori end. 16. Has there been any subsidy paid to these Conservators ?—The subsidy is payable by law. 17. Do you know whether anything has been paid to them since the flood in February ?—I cannot say ; but the information could easily be obtained from the Treasury. Mr. J. T. Thomson, Surveyor-General, examined. 18. The Chairman.] You are Surveyor-General?—Yes. 19. You have read the petition with reference to the flooding of the Taieri ?—Yes. 20. Are you acquainted with the locality ?—Yes, very well indeed. 21. In fact, I understand, you furnished a report on the subject ?—Yes; this is a copy (produced). 22. Will you state to the Committee as briefly as you can the position of the question ?—The position of the question is this: Once in every seven or eight years an enormous flood comes down the Taieri River, otherwise it is a river of small dimensions. These flood the whole of this large Taieri Plain. The Taieri River, in debouching to the sea, unfortunately goes through a very narrow gorge. These waters are backed up, the lakes increase, and this low land is flooded. Of course, the people settling upon this land have suffered very considerably during these floods. Each individual commenced to try to better himself. The first party who endeavoured to do so was Mr. Stevenson, who commenced with a small embankment on the east side of the river, near Outram. Then, after that, the settlers on the west side commenced to embank from Outram down towards a place called Scrogg's Creek, about three miles distant. My report shows that during floods the principal part of the flood waters crosses to the westward. [The witness read paragraph 16 of annexed report.] 23. What date is that ? —The report is dated the sth April, 1870. I saw the river in full flood. 24. The Committee understand there are some three or four miles of embankment on the west side of Outram ?—I have seen the embankment for two miles, but I think it goes down to here, past the gate-post opposite Milne's. 25. From your knowledge of the country, what effect would that embankment have ? Do you think it damages the people on the east bank ?—Most undoubtedly. It throws the whole of the water on this point, between Milne's and Greytown. It is astonishing that the people themselves have not been swept away. 26. What would be the remedy? —It is difficult to say. The Taieri presents one of the most difficult problems in engineering, owing to the difficulty of outlet and its enormous capacity for floods. It is enormously greater than we have in England even. [Witness read paragraph 7of his report, annexed.] 27. Where do you gauge it ?—At the bridge. 28. In fact, the water comes down quicker than it can be received at the gorge?— Yes ; and that stems back the current. 29. How far does that gorge dam the waters ?—About ten miles. 30. That would not affect these petitioners ?—lt would not affect them at all. It is the outcome from the mountains upon the plains that affects them. 31. In consequence of the tortuous nature of the river it does not deliver quick enough ?—Yes; and owing to this embankment as well. 32. Do you think it is possible by forming an embankment on the east side of the river to remedy this ?—lf they attempted to embank there the river would probably burst out in this direction and that. The fall is too great. In three miles the fall is no less than twenty feet. Now, with a river as large as the Molyneux, which is the largest in New Zealand, nothing could stand it. 33. As far as you can judge, there is no practical remedy?— There is one alleviatory remedy— namely, by making a new channel from the west side of the river through the West Taieri. In saying this, I must also remark that there are certain physical causes going on at present that affect the Taieri which it was not subject to before. In the first place, the country having been put under pastoral licenses the herbage has all been eaten down. When I first went over the country, in 1856, the herbage was two or three feet high. The clay and earth has all been beaten down, so that when floods come down they come immediately—much more quickly. Before I built this Taieri Bridge (about 1864 I think) there was a clay bank with all the flood-marks upon it: they must have been there for one hundred years. The highest flood-mark I took as my gauge. I placed my bridge six feet above that. When the flood came down it went six feet higher than before, and not only did it do that, but it cut out the whole of the low lands, widened the bed from 200 feet up to 700, and what was beautiful verdure before in these bottoms was turned into gravel. Mining also has had an effect upon it. The bed of the river has been raised by silt and shingle, and this will be a continuous process. The silt and sediment will settle where it first finds still water. The river now cannot force its way so quickly as it used to do through here, below Outram. 34. Is that all alluvial land ? —Yes. 35. Is there nothing to assist it ?—No. So that there are several operations going on to make it a difficult problem and extremely expensive. 36. Mr Dignan.] You state that on the east side of the river there is a small embankment ?— Yes; erected by Mr. Stevenson. 37. At his own cost ?—Yes.

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38. Was it done according to law ?—That is a legal question which I cannot answer. He made the embankment across a kind of blirrd gully. 39. Do you attribute the flooding of the other side of the river to any extent to that embankment? —Not the slightest. The prirrcipal overflow is before you come to the embankment. Mr. Stevenson made an embankment 200 or 300 feet in length to save his own little property, but it did no good to the rest of his neighbours. 40. If the owners on the opposite side were to do what Mr. Stevenson did, would it have the effect of relieving them to any extent ?—lt would relieve Shand's, Rennie's, and other farms ou west side. 41. Mr. Baigent.] Was not last year almost unprecedented for floods?— Yes; the Taieri comes dow m in great flood once in every seven or eis*ht years. They grow splendid wheat and corn from Outram to Blackie's, and then comes a year of famine. 42. Mr. Murray.] Are you aware that the proprietors on the west bank opposed Mr. Stevenson? —I heard they quarrelled about it; but whether they went to law Ido not know. 43. They seemed to consider that his putting up that embankment would injure their properties ? —They seemed to think so. 44. Without cutting a channel, but simply mounding the space on each side, would that not suffice to take the waters into the Waipori Lake ? —That would not be effectual, in my opinion. Of course you cannot put an embankment of sufficient length. You cannot put them ten chains away ; and when you get them ten chains from the bank, they are so low. The low river bed is 2780 only ; and when you get three-quarters of a mile from the river it is 2740 only. Here the beautiful cultivated land is below the river bed. The current is so enormously powerful at West Taieri bridge, and one mile downwards, that it will carry away anything. It has carried stones five tons weight several feet from the bridge. You cannot tell what the river would do. It has such a power and such a rapid declension that you cannot tell what it would do. It is a very bad case; that is the fact of the matter. 45. Mr. Burns] Do you recollect the distance of the gorge from the wooden bridge down to the sea? —About six miles. 46. Do you think that anything could be done there in the way of alleviating the matter ?—lt could be done, but you would have to spend hundreds of thousands of pounds. It is quite beyond the power of man to do it. 47. Are you aware whether any public money has been spent on this embankment ? —I do not think so ; they may have had subsidies. 48. Supposing public money was spent, would you consider it was profitably spent ?—No; the fact of the matter is that the settlers have been just like children, throwing away good money. They spend thousands, and floods come down and take all away; they do more harm than good.

REPORT ON THE FLOODS IN THE TAIERI PLAIN. Me. J. T. Thomson to the Seceetaey for Lands and Wobks, Dunedin. Sir,— Dunedin, sth April, 1870. I have the honor to acknowledge the receipt of your letter, dated 20th January last, enclosing a resolution of a public meeting held at Outram in reference to the floods that affect the Taieri Plain, and requesting me to report thereon. 2. in compliance therewith, as a first step to obtain correct data on which to found an opinion, I requested Mr. Assistant-Surveyor Johnston to take levels in various directions, which now having been completed, I am enabled to do so. 3. I visited the district last week and viewed the area subject to inundation on both sides and across the plain, and I find that, during great floods, about 54 square miles are subject to be covered with water. While the various settlers whom I visited had designs to ward off the floods from their own lands, I found that they had none to do the same office to their neighbours; nor was it difficult to see that, with these confined ideas, no general good could be effected, for such isolated attempts would only result in saving one proprietor to the equal injury of another; any measure, therefore, that can be supported, will require to be on a wider basis. To this end it will be necessary to take a general glance at the district and the river basins. The principal cause of the inundations is the River Taieri, but Waipori and Silver Streams add their quota to the damage, more particularly the latter as affecting the properties sought to be reclaimed by the meeting of settlers above stated. 4. The general characteristics of the Taieri River may be given as follows:—The distance from its mouth to its source is only 38 miles, but its very meandering course measures 120 miles; its feeders are principally in the Lammerlaw, 3,B2ofeet; Roughridge, 3,3sofeet; Mount Ida, 5,498 feet; and Rock and Prllar Mountains, 4,675 feet above the level of the sea. In tho first 30 miles of its course, it descends 2,62ofeet, where it debouches on the Maniototo Plains; thence 20 miles brings it to the Maniototo Lake, 986 feet above the sea level, the descent being 214 feet; thence 50 miles brings it to the Gorge at Outram, where it debouches on the Taieri Plain, the descent being 962 feet. 5. The Taieri River has therefore all characteristics of a mountain torrent. The same remark is applicable to the Silver Stream and Waipori, but whose minor basins do not call for particular description. 6. In a colony exact meteorological observations in sufficient quantity and in various parts of tho country are not to be obtained ; and, were it not for the labours of the Rev. Dr. Burns, D.D., who kept a "register in Dunedin in the early times of the settlement, we would be entirely without them. I find from his register and the subsequent official one that floods occurred at the following periods:—

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24th January, 1853, heavy. 29th May, 1861, 6th June, 1853, 28th January, 1868, 11th June, 1854, 3rd February, 1868, very heavy. Bth October, 1855, heavy. Ist January, 1870, heavy. Of these floods, that one on the 3rd February, 1868, rose the Taieri to a higher volume than had ever been recorded before, the highest flood-mark, as shown on the clay cliff at Outram Gorge, bein<; five feet below it. The marks placed by Mr. Adams, of Otakia, show also that the overflow of the Waipori Lake on the Plain exceeded the floods of 1861 and 1870 by 13 and 12 inches respectively. 7. As I had an opportunity of witnessing the heaviest flood at Outram shortly after it had culminated, I gauged the channel, aud estimated the rate of current per minute, which, on after-calculation, gives 4,653,068 cubic feet delivered per minute. I also gauged the river in its lowest state, and found a delivery of 45,000 cubic feet per minute. Thus the flood exceeds the low summer delivery by about one hundred times —a rate exceeding the most mountainous torrents in Great Britain. Having also gauged the delivery at the East Taieri Bridge of the highest flood level, I find it to be 1,186,960 cubic feet. Thus the outflow of the flood waters of the Taieri, not reckoning the effects of Silver Stream and Waipori, is about only three-sevenths of the inflow upon the plains; hence the Waipori and Waihola Lakes, and plains adjacent to them, act as regulators over which the flood waters distribute themselves until the channel of the outlet to the sea is able to draw them off. 8. The area of the Waipori and Waihola Lakes amounts to about 6 square miles, and the land subject to inundations to 49| square miles. The flood waters rise 9| feet above the low-water level of the former; and here a distinction must be made between still flood water of and adjoining the lakes and the flood waters that have a descent from the gorges down thereto —the former extending over 29 and the latter over 20| square miles. Thus 20J square miles of laird, situated principally on the northeastern end of the plain, may be reclaimed by drainage, without embankment; but of what may be thought advisable to reclaim of'the 29 square miles adjacent to the lakes must be done by the latter system. This question will much depend on the value of land, cost of labour, and the height to which the flood level of the lakes may be safely raised, consequent on the curtailment of their area of dispersion. To give an idea of ultimate measures I have calculated approximately the volumes of flood waters that lie on the plain at their maximum level, as given by Mr. Johnston's survey:— Cubic feet. On Waipori and Waihola Lakes ... ... ... ... 1,589,068,800 On 29 square miles adjacent to lakes ... ... ... 2,425,420.800 On 20^ square miles to N.E. of plain ... ... ... 571,507,200 Total... ... ... ... ... ... 4,585,996,800 9. As a check on the above result, I have also calculated the difference of the inflow and the outflow of flood waters during 24 hours, as obtained by gauge and measure of valley basins, and which may be stated as a fair mode of reckoning, as great floods are invariably preceded by wet weather, which fully saturates the ground, so that all channels are full. Cubic feet. ( By Taieri River ... ... 6,700,417,920 Inflow ... ... ]By Waipori River ... ... 475,047,936 (.By Silver Stream ... ... 66,908,160 7,242,374.016 Outflow by channel to sea... ... ... ... ... 2,717,222,400 Difference, or maximum flood waters that lie on the plain ... 4,525,151,616 10. As the channel leading from the Taieri Plain to the sea is deep, and in many parts bounded by steep cliffs on both sides, I anticipate that little improvement by widening and deepening can be made in this direction. The work would be very costly, attended by great danger to ihe channel, as it now is, by the falling of cliffs into its bed, and the improvement would at best be slight. In considering the subject, therefore, the improvement of the outlet must be left out. 11. The question, therefore, is, how much of the 29 square miles of swampy land near to the lakes, extending so far as Greytown, may be embanked aird rendered fit for agriculture? It is clear that the enlargement of the Taieri River bed, or the construction of new channels, will bring the flood waters down sooner on this area than at present. This, with curtailment of the area on which they now distribute themselves, must have the effect of raising the levels on the lakes and adjacent lands, which will affect vested interests in or near the margins. These matters will no doubt engage the attention of the projectors and engineers that may carry out the works. All that I need say at this stage is, that I find that by embanking off 10 square miles of flood waters the flood-mark on the lakes and swamp land adjacent will be raised 2'2ofeet; by embanking off 20 square miles, 5.36 feet; and so forth in increasing ratio. 12. A mode of alleviating the floods (and it is a common one in Europe) is to create regulating reservoirs in the course of the river above the lands sought to be reclaimed. 13. The Taieri has two positions well fitted for this purpose at the Strath Taieri and Maniototo Lake, but, as the tailings from the gold fields will have an increasing tendency to fill up the valley at these points, I need do nothing more than mention the fact. Were there no gold fields in the interior, it is evident that by penning up the flood waters their descent orr the plains could be made subject to regulatiorr and protracted discharge, which would have a most beneficial effect on the low hinds. 14. I come now to the drainage and reclamation works that I wouid advise in the interests sought to be served by the Taieri settlers. 15. To give a comprehensive view of what is required, it will be necessary to deta the following facts: —

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16. The Taieri River at the Outram Bridge has a breadth in high floods of about 9 chains, while 3 miles below this the breadth is only 3J chains, the depths also having decreased 8 feet. It is therefore evident that a larger portion of the flood waters escape over the banks between these two points, arrd actual observation shows that most of the overflow is directed across the site of the township of Outram aud the properties of Messrs. Borrie, Shand, and others, a small portion also finding its way to the north-east, over the property of Mr. Stevenson, against which an embankment has now been made by that gentleman. 17. From its point of inflow in the plain to its outflow at the lower bridge the Taieri River has a tortuous course of about fifteen miles, the fall between which two points at low water is 1783 feet; but here the tidal influence is felt in a rise at high w7ater spring-tides of 2 75 feet, and this influence extends in decreasing ratio up to the Silver Stream junction ; it is also very visibly felt at the Waipori and Waihola Lakes. Again, the fall of the river below the above two points, at high flood, is found to be 2902 feet. But the fall is very much greater near Outram, being equal to 975 feet at low water and 871 feet at high flood in three miles, i.e. 3 to 6 feet per mile. 18. Now it has been shown that the rate of inflow of the floods upon the plain greatly exceeds the rate of outflow below the lower bridge to the sea. The river when flooded, therefore, finding no sufficient exit, turns back by several wide channels, and flows over the Waihola and Waipori Lakes and adjacent swamps, distant from the Outram Bridge 17J miles by this course. Here the flood waters remain one or two days, according to the height of the flood. 19. To improve the connection, therefore, between the flood waters at their debouchure on the plain and those lakes is the first consideration. 20. To this end, it is clear that to widen and embank so long and tortuous a course as that of the Taieri would be futile. An auxiliary direct channel must therefore be sought, and this I have denoted on the accompanying plan, taking its course along the west edge of the great swamp, measuring a distance of nine miles from Outram to the Waipori Lake, and whose fall in that distance is at flood 2902 feet, and at low water 1783 feet. It is calculated to carry all the overflow that cannot be taken by the present channel. 21. In connection with this subject, the control of the flood waters of the Silver Stream is also of vital importance, and I have indicated an improved course for it—but which subsequent detail surveys may modify —with embankments till it joins the Taieri River. 22. Catch-water drains will also require to be led along the bases of the hills, to prevent a flow on the level lands to be reclaimed. 23. The principle of construction that I would advocate in the main drains and channels is what I have seen applied in similar positions in Europe: to place the embankment 2 to 5 chains distant from the channels, so that the floods have room to spread, and which side spaces, being permanently laid down in grass, will serve to prevent a tendency to alteration of course. The space can be beneficially used as pasture by running wire fencing at divisions of properties, secured from loss by fastening to the embankment. 24. I say nothing of the Waipori River, being beyond the area on which I had to report. 25. I find that the capacity of the present Taieri River channel, between Rennie's and Greytown, is only 1,173.744 cubic feet per minute; the new channel will therefore require to have a capacity to carry off 3,479,324 cubic feet per minute. Now, as the fall will be in the first four miles 325 per mile and that of the other five miles 096 feet per mile, the section of the new channel is designed for that capacity. 26. The channel for the Silver Stream may be calculated in the same way, whose flood volume is estimated at 46,464 cubic feet per minute, and whose fall from the Big Bush to the Taieri—a distance of three miles —is 1283 feet, or 427 feet per mile. In this case the section of the new channel to carry the flood water is designed for that capacity. 27. The capacity of catch-water drairrs will vary much, and are of minor importance, and are approximately designed and estimated; and I may remark here that, as the report only pretends to embrace generalities, careful actual surveys aud levels would require to be made in detail before the works could be contracted for. 28. The following estimate will embrace a scheme to reclaim 14,656 acres, being all that portion of the plain subject to floods to the north-east of that road line which stretches across the plain, between Blocks 111. and IV., Maungatua District, from Blackie's to McLaughlin's. 29. The scheme involves the cutting of a new channel 300 to 400 feet wide, and nine miles long, from Outram to Waipori Lake; the cutting of a new channel for Silver Stream, and au einbaukment across the plain. New channel for the overflow waters of the Taieri ... ... ... £128,936 New channel for the Silver Stream, as per plan attached ... ... 3,N01 Twelve miles of catch-water drains ... ... ... ... 4,056 Three miles of embankment ... ... ... ... ... 6,534 Four sluices ... ... ... ... ... ... ... 1,600 Total £144,927 30. Thus it will be seen that to stem the floods of the Taieri and Silver Streams from off the holdings in the settled part of the plain nearly £10 per acre will require to be expended. In the present state of the colony the scheme is, therefore, premature—a thing to be looked forward to. 31. My estimate will.no doubt, be disappointing to many; but, considering that the plain is a very limited area placed amidst a wide tract of surrounding mountains which pour their voluminous waters on it, the high cost of reclamation cannot be called surprising. 32. Subsidiary schemes to the one above stated may be suggested. The following may be executed with great benefit to the settlers on the east side of the proposed new channel, extending to the Silver Stream and beyond it; but it would involve the destruction of a good many holdings on the low flat at

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the foot of Maungatua and West Taieri Ranges. The scheme would be to throw all the waters of Taieri down the new channel by embanking across the present one below Outram; to cut the channel only two miles in length, which would take it below Grant's, and where it would spread itself over the great swamp and find its way by many channels to the lakes aud sea outlet. The easy practicability of this will be seen by reference to the section, which shows that the surface at Station F, near Mr. Grant's, is below the low-watermark of the Taieri at Outrarn ; and at half a mile below this the surface of the plain is three feet below that again. The cost of the work and extent of reclamation under this scheme would be as follows:— New channel of two miles for all the flood-water of the Taieri, with embankment ... ... ... ... ... ... £55,582 Twelve miles catch-water drains ... ... ... ... ... 4,056 Four miles of embankment ... ... ... ... ... 8,712 Four sluices ... ... ... ... ... ... 1,600 £69,950 33. The extent reclaimed would be about 11,500 acres, instead of 14,656; but, as stated above, damage to vested interests would be greater. 34. Failing either of these schemes being carried out, or modifications of them, I may here state that 5,504 acres, situated on the Silver Stream, may be reclaimed without damaging other interests, provided the lagoon is allowed to remain as a regulator, as it has always been in high floods. 35. A new channel, with the necessary embankments, catch-water drains, and sluices, might be completed, so as to effectually serve the end in view, for about £10,000. 36. 1 think I have said sufficient on this branch of the subject to enable the Government to decide on their measures. In however small a way it may be thought necessary to proceed, it is evident that legislation will be necessary at the outset, as no part of the inundated plain can be touched without improving one part to the prejudice of the other. Without a systematic basis of operation, therefore, supported by law, it would be injudicious to move a step. 37. This report would be incomplete without allusion to another subject which will more or less affect the agriculture of the Taieri Plain —namely, the gold fields operatioirs of the interior. Prior to their discovery the Taieri River was famed for its pellucidness ; now its character is entirely altered, its waters being charged with sediment more or less thick according to the season of the year. In the spring and winter months, when the water for ground sluicing is abundant in the interior, the waters are more charged than in summer and autumn, as then the water supply of the mountains is deficient. 38. At the time I lately visited the river 1 found the water comparatively pure; notwithstanding this, I obtained specimens of the same, and forwarded them to Dr. Hulme, who has been so kind as to test them. The result of his analysis is, that the summer water of the Taieri corrtains one part of sediment or mud to 1,920 parts of water. But, as properly remarked by an old Taieri settler, Mr. Donald Borrie, the water when taken as a specimen by me being three times clearer than it usually is, we would be justified in assuming that this result by no means represents the full quantity of detritus brought down. It may be remarked in proof of this, that the Ganges, urrdisturbed by diggers'operations, but affected solely by nature, brings down one part of sediment to 900 of water ; the Mississippi, however, contains only one of sediment to 3,400 of water, the various great rivers of the world varying much in this respect. 39. The basin of the Taieri River, above Outram Gorge being 1,730 square miles, and the rainfall being on an average of 34 inches per annum,* the fall will be 136,650,624,000 cubic feet of rain water per annum. Now, deducting oire-fourth loss by absorption arrd evaporation, which is the European rate for such climates and districts, the annual delivery at the Taieri Wain will be 102,487,965,000 cubic feet; dividing this sum, therefore, by 1,920, the quantity of mud in cubic feet will be obtained, viz., 53,379,150. This is sufficient to cover 1,225 acres annually with one foot thickness of mud, or the whole of the Taieri Plain with about one-third of an inch. 40. As yet the effects of the diggings are not apparent on the surface, farther than where swampy the vegetation is generally covered with slime, the river banks are subject to miry quicksands, and the bed at the Outram bridge has been found to have risen one foot nine inches ; but this latter may be due to the great flood of 1868, which washed away all jutting points of shingle into the bed for a long way up the valley. 41. In estimating the probable effects of the diggings, I have not for upwards of three years had an opportunity of examining the tailings of the principal seats of operations, viz., at Hyde, Hamilton, arrd Naseby, yet I then observed that in each case they were rapidly extending their lerrgth down to the Taieri River. At that time the light sediment alone was carried into it, but the time did not appear long distant when the heavier portions, such as sand, gravel, and shingle, would also be so borne on, more so especially during floods. This fact was pretty apparent even then, that with the extension and " prosperity " of the diggings, the Taieri River would have the greater burden to carry seawards ; and when we examine the Gold Fields map of the province, compiled by Mr. Vincent Pyke, which shows gold-bearing valleys round all the Rock and Pillar Mountains, Lammerlaw Ranges, Mount Ida, and Highlay, we cannot avoid the conclusion that the Taieri River will in that future extension and prosperity become the great sludge channel of a very important mining district. 42. Now, when the sediment alone reaches the lower plains effects are little felt; but when gravel, sand, aird shingle begin to roll down, then will the digger's gain be the farmer's loss, for the tailings will spread out even on the Taieri green fields as they may now1 be seen to do on the '' interval" of Gabriel's Gully and Wetherston's Flat. * Note. —To have mado the calculations more complete, it would have been desirable that the fall in the interior were known by actual observation. This has never bei-n observed. In the interior the plains are said to have a dry climate, yet the high fall on the mountains may compensate for this.

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43. That I am not an unreasonable prognosticator of evil, I beg to append the remarks of a late intelligent writer on Califorrria ; and may here add that the cases may not be entirely parallel, yet the warning is of sufficient importance to call for the timely offices of our legislators and engineers. 44. To gain an intelligible view of the effects of the upper valley being filled with gravel, &c, we will require to consider the fall of the river from the Maniototo Lake to the Taieri Plain. This has been stated before to be 962 feet in fifty miles, or at the rate of 1925 feet per mile, the descent being pretty uniform. This is a far greater rate of descent than is applicable to the "absolute torrents" of English hydraulic engineers, whose velocities are reckoned at 480 feet or more per minute. Now, as a current of 180 feet per minute scours angular stones as large as an egg, and a rate of 300 feet scours conglomerate, the Taieri in flood will bring down tailings of every size and description to the lower levels. 45. If, then, the interior gold fields are to be prosperous and extend, measures will require to be energetically taken in the agricultural district of the Taieri to deal with these tailings. 46. It is true that a generation may yet pass away before they become absolutely obnoxious to tillage, yet, under the above circumstances, the event is certain, and the action will be continuous till the gold fields are worked out. 47. With these facts before us, then, we must neglect the limited interest for the large majority —the inconvenience of a few for the safety of the whole. 48. The proper engineering measure for dealing with the floods of the river is, therefore, the second one mentioned—namely, to confine its channel entirely to the west side of the Plain, cutting it off by a strong and high embankment from the fertile fields of the central and eastern districts. This would be a measure adequate to the wants of centuries ; any other would be ineffective and temporary. I have, &c, J. T. Thomson, The Secretary for Land and Works, Dunedin. Civil Engineer.

APPENDIX. The Foot Hills — Gold Mining. It is a sad pity to see the beautiful rivers of California so spoiled by the gold-washings from above. The Sacramento is yellow with the sand from these works in the mountains, and the fine salmon which used to fill its streams are being driven away each year. In a short time, unless efficient measures are taken to preserve the fish, the rivers of the State will be stripped of a most valuable product, as similar streams have been in New England. The sea fish of San Francisco, however, arc abundant, and of many new and remarkably fine varieties. The mining in the Foot Hills is producing another remarkable effect: it is driving out the farmers from the river bottoms to the elevated land. These flats were always subject to periodical overflows, but, as the floods seldom reached beyond a well-known limit, and as they deposited fertilizing sediment, the cultivators could adapt themselves to them and found their advantage in them. But since the enormous hydraulic washings in the Foot Hills, or the Sierras, this has all been changed on account of the filling up of the mountain streams with gravel and soil. In many of these streams whole hills have been sluiced away, and have filled up the rivers from twenty to forty feet. When the winter-floods come, they pour down these channels and carry the soil and gravel to the valley streams, filling them up to the brim, causing floods, and thus burying thousands of acres of most valuable land every year under this sandy and pebbly deposit. I heard of one instance in Yuba Couuty of au orchard of seventy-five acres worth from §50,000 to $75,000 thus completely destroyed, and of many similar cases of smaller vineyards and farms. The following from the Alta newspaper will illustrate this destructive action of man on nature: — " Marysville, once the best-built aud neatest inland town of our state, with a flourishing commerce, has been retrograding for some years past, from changes incident to California. The bestpaying orchard of the State was Briggs'. This consisted of ninety acres of assorted fruit trees, on rich, sandy loam, kept moist by infiltration from the river. The fruit of this orchard was the earliest to reach the market, and, until prices fell to their present level, it paid well to send it to San Francisco, even at heavy cost of steamboat freight. What has become of this celebrated orchard, which was valued at $200,000 ? It is now a willow copse ! Its trees, which were so beautiful and so fragrant in full flower of spring time, and whose rich show of fruit, always heavily laden, was the greatest attraction on the highway, now gladden the eye no more for ever. In its place stands a wilderness of rank willows, overtopping its former wealth of fruit trees, and blotting out the record of their history." Dr. Tregarden's rich and beautiful orchard of forty acres, in nearer proximity to town, has shared the same fate, and Briggs' second orchard of 200 acres is fast following it. Nearly all that exceedingly fertile bottom land that lined the banks of the Yuba for miles above is also for ever blotted out, and the work of devastation still advances along the bottoms of the Feather River, below the confluence of the Yuba. In time not distant, the whole of those rich dark soil bottom lands will be one barren waste of sand. This sad change is but a type of the utter desolation that has already ruined the bottom lands everywhere along the streams that come from the gold mines. Every year millions of tons of earth, gravel, and sand are sent down the rivers that go from the mines toward the plains below. Every year there is added so much to the channels of deposition that the beds of the streams are elevated, and their waters spread more and more over the alluvial bottomlands, and bury them under barren sands beyond redemption.

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Let it be understood that these rich lands count their acres by thousands upon thousands, that they are smothered under from five to twenty feet of barren sand, and tho eternity of their extinction from the wealth of the State will be comprehended. The Sacramento River, though further removed and broader in its base, is not less notably being uplifted, and year by year its ever muddy waters are spreading over the flat and marshy land on its borders. The greater part of this destruction comes from what are called hydraulic diggings. These are the richest lands for tillage in the undulating country of the gold ranges. They have a substratum of gravel which contains grains of native gold. To get a cheap separation of the gold from the gravel it is necessary to tear down the low elevations, varying from 500 to 200 feet, with the whole covering of rich top soil with the gardens and orchards, houses and fences, that are on them. The dry gold is found to be,there ; the farm is devoured, and in an incredibly short time the piping water-jets, under a pressure of 100 or 200 feet, have torn away the gracefully swelling landscape of 200 or 300 ornate acres, and left in its place a porrd of dirty water, with a broad border of huge boulders of rock, with cobble stones and barren gravel—a picture of utter ruin. The devastation could not be more complete if it were the last day, and the demons of destruction had been let loose to desolate the earth, that not a green thing should grow on it thereafter for ever ! The price of this awful ruin is probably some ten or twelve millions of gold dollars per annum, the product of this particular form of mining. It brings, for the present, a large equivalent for the sacrifice of the fine vineyard and orchard land it abstracts from the food-producing capacity of the State; but in the end it may be regarded as a poor compensation : the gold passes away, while the land, with wealthy homes it has raised, would have endured from generation to generation.—" New West," by Charles L. Bruce. By Authority: Geoege Didsbuby, Government Printer, Wellington.—lB77. Price 6d.]