Computer Simulations – Expert Evidence: LAWRENCE v KEMPSEY SHIRE COUNCIL 3429 of 1986 SUPREME COURT OF NEW SOUTH WALES EQUITY DIVISION
One must be very careful with computer predictions. Usually they are the result of someone making assumptions and assessments of various vital factors and feeding these factors into the comPuter. Unless those assumptions and assessments are proved by evidence (or are conceded to be valid) the mere fact that a computer produced a prediction is of no evidentiary value whatever. It is clear [*72] law that an expert witness’ evidence on matters of fact is in the same position as the factual evidence of any other witness; English Exporters (London) Ltd v Eldonwall Ltd 1973 1 Ch 415, 421; Pownall v Conlan Management Pty Ltd (1995) 16 ACSR 227, 231. That problem cannot be overcome merely by feeding unproved factual material into a computer and treating as evidence what the machine produces.
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NEW SOUTH WALES UNREPORTED JUDGMENTS
LAWRENCE v KEMPSEY SHIRE COUNCIL
3429 of 1986
SUPREME COURT OF NEW SOUTH WALES
1995 NSW LEXIS 11428; BC9504607
20-24 March 1995 (Wauchope), 28-29 March 1995 (Sydney), heard;
12 May 1995, delivered
CATCHWORDS: [*1] ENERGY and RESOURCES 27 – Riparian rights Right to have water flow
undiminished in quality – Provision of “harmless” effluent affects quality.
EVIDENCE 138 – Computer results – Hydrologist’s computer model of flood
patterns – Inadmissible unless underlying assumptions properly proved.
FENCES and BOUNDARIES 3 – Water boundary – Torrens land – Non-tidal stream
made tidal by council works – Ad medium filum rule applied.
LOCAL GOVERNMENT 40 – Torts – Nuisance caused by sewerage works – Statutory
defences considered – Local Government Act. 1993 s733.
NUISANCE 3 17 – Water – Low floods causing sewerage effluent to pond on
plaintiff’s land – Injunction refused – Damages awarded.
WATER 18 – Damage – Council’s sewerage works – Causing effluent to pond on
JUDGES: YOUNG J
HIS HONOUR: The plaintiff sues for an injunction and for damages in respect of an alleged nuisance in allowing sewerage effluent to enter Christmas Creek near Kempsey and to flow out of the creek and to pond on and deleteriously affect his grazing land. He also sues for infringement of his riparian rights. The proceedings were heard by me at Wauchope commencing on 20 March, 1995 and I sat [*2] for a week in that town, though I had a view at Kempsey on the Tuesday of that week. The balance of the case was heard in Sydney. Mr Nigel Cotman appeared for the plaintiff, Mr Michael Murphy appeared for the defendant council.
The plaintiff is the proprietor of four blocks of land abutting Christmas Creek. He says that since the defendant or its predecessor did work on its West Kempsey sewerage treatment plant in 1976, his land has deteriorated in the manner I will consider shortly. Because these proceedings were only commenced in 1986, the Limitation Act operates so as to prevent any recovery for damages caused before 8 September, 1980. It is clear that at least since 1980, the plaintiff has been the proprietor of the relevant land. The West Kempsey sewerage plant is at the Northern extremity of the former Kempsey Municipal area. The sewerage is collected at the plant and passes through two ponds before leaving the plant and finding its way into Christmas Creek. Prior to 1976, the effluent passed over land then belonging to a Mr Griffin and passed into the creek near the boundary of Griffin’s land and the Kempsey Saleyards. I will call this point of entry into the creek Point [*3] X. A drain was constructed to pass the effluent to the creek by a more direct route. This drain joined the creek at a point further to the West of Point X, at a point I will call Point Y.
In 1976, a channel was constructed along a road reserve further to the West again. Since 1976, the effluent has passed along this channel and entered the creek at a point I will call Point Z, which point is not far distant from the plaintiff’s Western boundary.
The plaintiff’s property is vacant agistment lands on the Northern side of the creek, that is, across the creek from Griffin’s land.
The plaintiff says that his land is in a particularly good position because it provides agistment for stock even in times of drought. Furthermore, because it is within walking distance of the Kempsey Saleyards, the plaintiff was able to buy cattle at the saleyards when prices were depressed, keep the cattle on his property without incurring transport costs and then resell at a profit a short time later. The plaintiff is very familiar with the area having lived there most of his life. He can remember the creek in 1940 when he was a boy of fourteen. He says that at that time the creek was about 15 metres [*4] wide and relatively shallow. The measurement that the plaintiff gave was “up to the kneepad of the horse” which he eventually translated as being 3’6″ to 5′ 6″ ie between one and one point seven metres. There were however a series of five deep waterholes in the stretch of the creek fronting the plaintiff’s property which were extremely valuable in time of drought. The plaintiff thought that the first council sewerage works which affected the creek were effected in the early 1940s. The defendant’s evidence was that these took place about 1937.
The next major work was done in 1976. This was the work to which I have already adverted. In about 1985, the defendant council, in conjunction with the Glenrock-Tennessee Drainage Union deepened the creek. The purpose was to extend the distance for which the creek was tidal so that tidal forces would force water from the Macleay River to flush the creek fronting the plaintiff’s land.
The council did further work in the area in 1993. This worked changed the method of effluent dispersal from discharging the effluent into the creek to what is called land irrigation. That is the effluent, after various biological matter has been destroyed by [*5] sunlight in a holding pond for three weeks, is sprayed out over the surface of land now owned by the council, until it eventually flows in or over that land before entering Christmas Creek. There were other works done on Christmas Creek from time to time between 1937 and 1995 which had some influence on the land, but the periods I have noted map out the main divides.
Both parties called expert witnesses. The agricultural expert for the plaintiff was Miss Julia A Vincent, whilst Mr JWS Mackenzie gave agricultural expert evidence for the defendant.
I will analyse the evidence more closely in due course. However, one can readily see the ambit of the dispute when one realises that most of Miss Vincent’s findings are contradicted by Mr Mackenzie. Miss Vincent supported the plaintiff’s assertions that the plaintiff’s land had a carrying capacity of 200 head of cattle. Mr Mackenzie stated that the carrying capacity of the plaintiff’s land was only ever 35 head. He says that the land was always poor with relatively high acidity and that the tests show that the effluent affected land and adjacent land are at present not significantly different. Mr Mackenzie says that the extra nutrients [*6] in the creek are not a result of any one factor. He further says that the growth of water hyacinth and smartweed is not attributable to the effluent. Mr Mackenzie says that he has actually seen the plaintiff’s cattle drinking from the creek, a matter which Miss Vincent denies. In short, Mr Mackenzie’s evidence, if accepted, would prove that there was no effect to the plaintiff’s land from the effluent. Again, Mr Noble, the plaintiff’s valuer says that similar land to that of the plaintiff’s land had a value of $ 1750 per hectare in 1992. Mr Cotsell, the defendant’s valuer thought the figure was $ 1800 per hectare. Mr Noble considered that the plaintiff’s land has been detrimentally affected so that 40 hectares of flat land is now only worth $ 750 per hectare whilst the remaining 74.4 hectares has fallen to $ 1500 per hectare. Thus, he says, the plaintiff’s land is worth $ 60,000 less than had it not been affected by the effluent. Mr Cotsell, on the other hand, did not consider the plaintiff’s land to be detrimentally affected at all and said it was still worth $ 1,800 per hectare.
Both parties filed points of issues which were substantially identical, the plaintiff’s document [*7] merely being more detailed than the defendant’s. However, as often happens, during the course of the trial, some issues were not pressed and the results of others became obvious.
Thus the real questions are: A. What, if any, riparian rights does the plaintiff possess? B. What is the boundary of the plaintiff’s land in the vicinity of the river? C. Is the plaintiff entitled to recover in nuisance? D. Did the effluent that flowed off the defendant’s land flow onto the plaintiff’s land? E. If D is answered, “Yes”, did the effluent have a deleterious effect on that land? F. What, if any, damage was caused by the effluent? G. Was that effect reasonably foreseeable? H. Did the defendant Council act properly under its statutory powers? I. Is the Council protected under s733 of the Local Government Act, 1993 or the corresponding section of the repealed Act? J. Is the Council protected by the relevant work being done within a Drainage Union? K. Is there any estoppel operating against the defendant to prevent it from asserting that the work was done under the aegis of the Drainage Union? L. What remedy should be given if the plaintiff succeeds? M. What is the proper quantification of the [*8] plaintiff’s damages? I will deal with these issues in turn. I then will deal with a question of admissibility of evidence on which I reserved, namely: N. Are a scientist’s predictions of water flow based on a computer model admissible?.
In view of the agreement of the parties that time should be given them after delivery of these reasons to consider the form of order and cost, it is not necessary to consider at this stage what orders should be made as to costs. A. There is no doubt that the plaintiff has riparian rights. Riparian rights refer to the rights possessed by the proprietor of the banks (ripa) of a stream. The congerie of rights classically defined by English law by this term has been modified by statute in NSW, see Van Son v Forestry Commission of NSW, Cohen, J (unreported) 3.2.1995. In that case, his Honour confirmed that the effect of legislation has been to remove a good deal of peoples’ riparian rights. However, he said that the riparian right to take and use water “without sensible alteration in its character or quality” remain. (at 31).
The words, “without sensible alteration in its character or quality”, derive from the speech of Lord Macnaghten in Young v [*9] Bankier Distillery Co 1893 AC 691, 698. They were also used by Latham, CJ in H Jones and Co Pty Ltd v Kingborough Corp (1950) 82 CLR 282, 299. See also Embrey v Owen (1851) 6 Ex 353; 155 ER 579.
There was some debate before me as to what was meant by water of good quality. Mr Murphy submitted that it meant water that might be drunk. He put that even if one had a disinclination to drink the water because it contained effluent, if, on proper chemical analysis the water was safe to drink, then, the water was of good quality within the meaning of the rule.
In Young’s case, which was a dispute between a mine owner upstream and a distiller downstream, the mine owner argued that the distiller was still receiving pure water and that the water was not sensibly altered by reason only of its becoming harder. Indeed, the trial court had held that it had not otherwise been affected by the mine owner’s activities. this argument was roundly rejected by the House of Lords. If the water was affected in a way which made it unfit for any of the purposes for which a downstream owner was entitled to use it, it was [*10] sensibly affected (see especially at 696). Even a change in temperature in the water may well be a sensible alteration, see at 700. In Brocket v Luton Corp 1948 WN (Eng) 352, Vaisey, J said, (according to Coulson and Forbes on Waters and Land Drainage 6th ed (Sweet and Maxwell, London, 1952, at 218) “I cannot believe that a riparian owner would be obliged to submit to the conversion of clear water into water dyed, for example, bright crimson with cochineal, which I believe to be a perfectly harmless ingredient.” In Embrey’s case, the Court of Exchequer seemed even to be troubled by adjectives such as “sensible” or “appreciable” and seemed to say that except in cases where the damage by the alteration was so small that it was covered by the maxim, “de minimis non curat lex”, the plaintiff could recover.
It is quite clear on the evidence that the water has a different composition as a result of the effluent flowing from the defendant’s land. Not only is it harder, but it also contains extra ingredients. It may or may not be water which those who are not squeamish may drink without ill effect, but that is not the test. The test is whether as a matter of fact and degree the water [*11] now is sensibly different to before the time when the defendant did its work. The scientific evidence is all one way that the water is sensibly different. The plaintiff suffered damage through this alteration. He was receiving water which was enriched with nutrients which promoted the growth of water hyacinth and smartweed. As I will demonstrate later in these reasons, he suffered escape of such water onto adjacent land whose pasture was affected.
The plaintiff also complained about the increased flow of water. For the reasons Cohen J set out in Van Son’s case, this sort of problem can no longer be considered as damage to riparian rights.
B. There was debate before me as to the boundaries of the plaintiff’s land, whether they were the bank of the creek or the centre line of the creek.
In Micklethwait v Newlay Bridge Co (1886) 33 Ch D 133, 145, Cotton, LJ said, “… the rule of construction is now well settled, that where there is a conveyance of land, even though it is described by reference to a plan, and by colour, and by quantity, if it be said to be bounded on one side by a river or public thoroughfare, then on the true construction of the [*12] instrument, half the bed of the river or half of the road passes…”. This principle of construction is usually known as the Ad Medium Filum Rule. The plaintiff’s certificates of title describe his land by plan only. The lands abutting on the creek are comprised in two certificates of title. Certificate of Title Volume 2043 Folio 206 has a plan where the boundary is shown as a dotted line which is placed within Christmas Creek, but not in the centre of the creek. Certificate of Title Volume 2993 Folio 99 has a similar dotted line, but this time drawn just outside the bed of the creek. In view of the decision of the High Court in Lanyon Pty Ltd v Canberra Washed Sand Pty Ltd (1966) 115 CLR 342 the plans on the certificates of title in this fashion are insufficient of themselves to rebut the presumption. There being no other evidence the presumption should be held to apply.
There is the complicating factor in the present case that, although as at the date of grant the creek was non- tidal, as a result of works done by the defendant or the Drainage Union, it has become subject to tidal influence since about 1985. The ordinary presumption with respect to [*13] tidal waters is that the proprietor holds up to the mean high water mark and the Crown holds below that line, AG v Chambers (1854) 4 De GM and G 206; 43 ER 486. However, one must look at the situation at the time of the grant. At that time the stream was non-tidal and the Ad Medium Filum Rule applied. It cannot be thought that anyone intended that the boundaries of land adjacent to the creek were to be affected by making it tidal, nor that the Crown would suddenly appear as the proprietor of the land below mean high water mark. This result is analogous to the result where there is accretion caused principally by reason of artificial works, see AG v Leighton 1955 NZLR 729. Thus the boundaries remained as before, subject, of course to a change if by gradual accretion, the creek changes course. Thus, the boundary of the plaintiff’s land where it adjoins the creek must be determined as the centre line of the creek.
C. As to nuisance, there is clearly no doubt that the plaintiff is a land owner. In the context of this case, nuisance will be committed if the defendant is permitting a deleterious substance to flow off its land onto the plaintiff’s land, [*14] causing damage to that land.
In Van Son’s case, Cohen, J said at 30, “Private nuisance occurs when there is unreasonable interference with the use and enjoyment of land. That interference may result from physical damage to the land or it may consist of an interference with the comfort or amenities enjoyed on that land, such as by offensive smells or excessive noise. There may of course be circumstances where both physical damage and loss of enjoyment of amenities occur as a result of the same source of nuisance.”
The plaintiff gave evidence as to having been affected by four problems. The plaintiff says that from 1976, his land has been seriously and deleteriously affected by the defendant’s activities. The plaintiff says that the defendant has committed the tort of nuisance. The gravamen of the plaintiff’s complaint is that the work done in 1976 had the effect of forcing nutrient enriched fluid into Christmas Creek which detrimentally affected him. In particular, the plaintiff says the following has occurred: (a) Bogging of cattle became severe at least up until the plaintiff connected some troughs to the town water supply in 1986; (b) Water hyacinth exploded from covering 50 [*15] per cent of the plaintiff’s creek frontage to 100 percent; (c) The amount of feed that the land produced fell off dramatically; (d) Smartweed began to replace native pasture up to the high water flood level. The plaintiff says that, in 1973, he was able to support approximately 200 head of cattle on his property. He says that, in 1973, it was extremely rare for him to see a beast experiencing difficulty in becoming bogged whilst drinking at the creek. Since at least 1980, this phenomenon has not been uncommon.
The plaintiff supported his case with his own evidence, that of some neighbours and family plus some expert evidence. The plaintiff’s principal expert was Miss Julia A Vincent, a consultant agriculturalist.
The defendant presented evidence from its own officers, from neighbouring occupiers and from experts including Mr Webb an expert hydrologist and Mr Mackenzie an expert agriculturalist. The plaintiff’s description of what has occurred on and around his property is consistent with small scale inundations being a matter of concern for a long period of time. Those inundations were most destructive after 1976 first because blockages of the creek occurred along the whole [*16] of the creek-frontage causing effluent to overflow and secondly the effluent was no longer “treated” by ponding on the Griffin land before discharge into the creek. The plaintiff said at T 39: “Q. The question was, when you complained to council in 1973, you told us you believed that the water hyacinth was somehow causing floods to your land? A. Yes. Q. How do you believe the water hyacinth was causing floods to your land? A. Because it was blocking the creek in the lower points. The creek was overflowing onto my land. Q. Where do you say those blockages were? A. Along my frontage to the creek. Q. So you had a flood on your land, but no flood below the Saleyards Bridge, is that what you’re saying? A. Correct.
Q. So it was a purely local flood? A. If you put that way, yes. ………… Q. It wasn’t Saleyards Bridge which was banking the water back? A. No. Q. It was water hyacinth in the creek above Saleyards Bridge? A. Yes. Q. Forming some sort of clumps in the creek? A. Yes. Q. And the water obstructed by those clumps would build up? A. Yes. Q. And flow across your land? A. Yes. Q. And down, back into the creek on the other side of the clumps? A. Not necessarily. Q. Where did [*17] the water go? A. Out onto my land. Q. Where did it come back into the creek? A. It didn’t go down. It stopped on my land and went on to the neighbour’s land where it was lower. The downstream of Saleyards Bridge, the land is higher again. Q. So the water came across the clump of water hyacinth into the creek? A. Yes. Q. In your creek front and flowed out across your land? A. Yes. Q. And the creek below that clump of water hyacinth was full of water too? A. Had water in it. Q. And that water was just as high as the water behind the clump of water hyacinth? A. I don’t know. Q. So you don’t know? You didn’t look at it? A. Yes, I looked at it. Q. What did you see? A. There seemed to be water in it. Q. And the height of the water below the water hyacinths clump, did that seem to be the same height? A. It seemed to be lower. Q. So there was nothing to stop the water coming out onto your land and back into the creek? A. Yes. Q. If the water was lower in the creek, what was stopping it going back? , A. Higher ground in the creek bank. Q. And there was some water going onto your land that got trapped by high ground? A. Yes.” It is common ground that the lip or cusp of the plaintiff’s land [*18] is low in relation to the top of the creek banks. It falls away into large shallow ponded areas that retain water. Those areas are clearly lower than the surrounding land, upstream or downstream. The cusp restricts ponded water from finding its way back into the creek.
Mr Brady who owns the property on the same side of the creek as the plaintiff downstream from the plaintiff’s property gave evidence supporting the plaintiff. He said he had fenced the creek to prevent his cattle from drinking the water or from becoming bogged. He had had the experience of having to rescue a bogged calf. Mr Prior who had long experience in the area, deposed to noticing a distinct deterioration in the plaintiff’s land since 1980. Mr Crossingham who owns property upstream gave similar evidence.
On the other hand Mr A Griffin gave evidence that water hyacinth was always a problem in Christmas Creek and that the effects of flooding have been no greater after 1976 than before. He says too that his cattle drink the water from the creek without any ill effect.
However, Mr G Griffin who owned land on the Southern side of the creek and who gave evidence for the defendant agreed with a lot of the topographical [*19] evidence given by the plaintiff’s witnesses. At T 282 he was asked: “Q. In the areas where the water hyacinth grew in your observation, it was growing most prolifically and quickly where it had access to the effluent? A. That’s right. Q. And was banking up into a solid mat from bank to bank in the creek? A. Yes. Q. So that it didn’t move for the wind or the water – it just sat there? A. That’s right. Q. Any additional hyacinth then got packed into the mat of hyacinth? A. That’s right. Q. So that in the end the creek was effectively choked by the hyacinth mat? A. That’s right. Q. And you would expect, as a farmer, I take it, to have water banked up behind such a mat of hyacinth? A. Yes. Q. Wouldn’t you? A. That’s right. Q. Because this made a wall of hyacinth root all across the creek bed? A. That’s right.” Mr Cotman points out that this process is the destructive one described by Miss Vincent. It is the process that is irrelevant to the type of large scale flooding described in the reports of Dr Webb the defendant’s hydrologist. Major floods come and go without depositing soluble matter on the soil because, by definition, that material is in solution and stays in solution. It is [*20] the constant small inundations that deliver the nutrients to the plaintiff’s land.
Miss Vincent gave evidence to support this view. She said in her report of 17 December, 1993: “Flood waters containing pollutants, would normally be carried from the land by surface drainage, or by percolation through the soil, into the sub surface water table, then by natural lateral movement, drain out of the soil into the nearest water course, in this instance Christmas Creek. Some absorption of water soluble pollutants by the soil humus will occur during this process, but, for as long as the pollutants remain in solution, the majority will pass from the land with the water.
If however the water is ponded on the land for significant periods of time by a high level of waters in the drainage watercourse, ie, Christmas Creek, the process of evaporation becomes the dominant force acting on accumulated water. This process concentrates the pollutants. This concentrated solution percolates slowly down through the profile, being adsorbed onto the soil particles by the interactions of soil organisms, the pollutants and organic matter to form polluted humus which then adheres to the soil peds.
Once [*21] the soil solution is saturated with the pollutants, the remaining pollutants are deposited on the surface, as evaporation crystallises them from the super-saturated solution.
They will therefore remain on or in the soil until they are removed by dissolution following adequate rainfall or flooding. or are broken down again by soil organisms or removed from the humus by the roots of plants.
This being the case, the pollutants would be held in the soil for long periods of time. The process described above, vis ponding after rainfall and/or flooding, evaporation, concentration of the solution remaining on the land, percolation into the soil, incorporation into the humus, would have the effect of delivering directly to the soil, and the pastures, any pollutants contained in the water on the land.
PASTURE GROWTH Such a delivery, would cause the pastures growing on the land to be directly effected by the pollutants, the root systems effected by those pollutants as they are deposited within the top soil, directly in contact with the primary feeding roots.”
When she was in the witness box, Miss Vincent was asked (T 248): “Q. … in your hypothesis about the delivery of pollutants [*22] to the soil on Mr Lawrence’s property, is flowing water per se a problem where that goes onto a property, flows across and goes away? A. No. Q. If you were told the water flowed across Mr Lawrence’s property and flowed across someone else’s property and went away, would you expect that to be a problem to either of the properties? A. No. Q. If you were told that there was substantial and lengthy ponding of these waters after a flood has receded and then a process of, principally, evaporation to get rid of that water, would that then be a problem under your hypothesis? A. Yes, if it contained elements which were detrimental to the soil.” Miss Vincent also said at the same page: “Q. Were you relying on Mr Lawrence when you say that the property flooded more often? A. Yes, except I do have records – historical records of flooding over the years that he is referring to and the fact that he – him saying that the property flooded more frequently coincides with my history records from the Meteorological Bureau. Q. And these Meteorological Bureau records, what point do those records measure at? A. These are only records of rainfall, not measurements of height of water. Q. If I am understanding [*23] you – and correct me if I’m not – you are saying that the meteorological records indicate during the period you quote there was heavy rain more often? A. Yes. Q. And that the more frequent floods that Mr Lawrence was suffering were because of more frequent rains? A. Yes, the water remaining on the property longer because of the slow drainage rate.”
This evidence is in contrast with the evidence called by the defendant that the plaintiff’s land is in no worse condition than neighbouring land save that the plaintiff had not taken proper care of his land. It should be noted that even if conventional floods are considered, Dr Webb concedes that at the tail end of floods, as the creek drops and the effluent returns within its channel, the effluent plume will reach the opposite lands. That is the second form of inundation that might explain the readings for nutrients and other minerals detected in Miss Vincent’s samples.
I accept the plaintiff’s evidence and those neighbours who gave evidence on his behalf. Further, for the reasons set out in Section E of these reasons, I accept the expert evidence called by the plaintiff. Thus I accept the plaintiff’s basic proposition that he has [*24] suffered an actionable nuisance at the hands of the defendant.
D. There seems no doubt at all in my mind from the evidence that I have already quoted, that the effluent flowed into the creek and onto the plaintiff’s land abutting the creek.
E. The plaintiff says that his land was damaged because of its lessened carrying capacity, and by its becoming boggy.
As to carrying capacity, Mr Cotman submits that the carrying capacity of the land was reduced, as it necessarily must be, as pasture grasses were replaced by weeds.
Miss Vincent evaluated the prior carrying capacity of the land as follows (at T 240-241): “Q. What do you think it could have carried previously? A. Year round under good conditions? Q. No, year round under ordinary conditions? A. How many hectares is it… 114.4. Approximately 70 head. Q. You have told us, Miss Vincent, that 40 hectares of the 114 has been affected? A. Yes. Q. And that leaves 74 hectares not affected? A. Right. Q. Just on that proportion, if it could carry 70 cattle in ordinary conditions, it could carry a lot more than 12 on the high parts of the land alone, couldn’t it? A. Well, when I looked at the animals on his property and I looked [*25] at the boundaries of the property and I looked at the growth of the pastures which were all over it, as well as the high areas, my assessment was 12 at the time. Q. So the high areas had been eaten down? A. Yes, had been eaten down. Q. So your assessment of 12 is on the basis of the property when you looked at it had been eaten out? A. Yes. Oh, not only – no, no. Q. What else did you assess it on? A. The percentage of weed infestation, the lack of relevant pasture species in that area which has been affected. Q. Miss Vincent, my point is this, 74 hectares not affected, 40 hectares affected, that would not reduce the carrying capacity from 70 to 12 even if you destroyed and fenced off the 40 hectares? A. I see what you mean. Maybe I was estimating that on the 40 hectares, not on the whole 114. Q. So in addition to the 12 cattle the property can now carry, it can carry however many it used to carry on the high land? A. If that high land is not degraded as well, having been over-grazed over several decades. Q. Has Mr Lawrence’s high land been degraded over several decades by over-grazing? You have seen it? A. To a degree I would think so, yes.” At T 248 she continued: “Q. What would [*26] you treat as the year round carrying capacity of the high ground on Mr Lawrence’s property in a normal season? A. I would think most likely one animal per two hectares. Q. Are you assuming in that answer some access to water down in the creek? A. Yes. Q. Across the creek flat land? A. Yes. Q. If you assume access to the creek was impeded by for example a barrier of smart weed or whatever, does the high land have any inherent carrying capacity? A. None at all. Q. Indeed, does any of the property have an inherent carrying capacity? A. No. …….. Q. Going to other properties that you have seen in the district which have this configuration of creek flats and some high ground? A. Right. Q. What would you expect to be the year round carrying capacity of such a property in this district? A. I would think one for two hectares. ……… Q. I think you said a property in the district of that configuration would carry one beast per two hectares? A. Yes. Q. If you assume that the low land pasture is damaged in the way that you observed on Mr Lawrence’s property in 1992 – A. Yes. Q. – what would your estimate of the reduction in carrying capacity be in such a property? A. Over the whole [*27] property? Q. Yes? A. It would be one per three hectares on the remaining area which was still good, as long as there was adequate water supply. Q. You said to his Honour a moment ago that the flats in a damaged condition would come back to one beast per three hectares on the high ground? A. Yes. Q. Why did you add the qualifier ‘on the high ground’? What is the impact on the low ground? A. The reason being that higher ground usually is not as fertile a place – creek or river flats usually – usually have a higher fertility than higher ground. Q. What would be the carrying capacity then per hectare of the lower ground? A. In its undamaged state? Q. First of all in its undamaged state and then in its damaged state? A. Okay. Normal creek flats – improved or unimproved? Q. Unimproved? A. Okay, roughly one animal per two hectares. Q. And in the damaged condition? A. None or almost none. As it is now it really – all of the damaged area has almost no species which are suitable as animal feed. Almost all of it is useless as animal feed.” The defendant’s experts deny that there is any lessening of the carrying capacity of the plaintiff’s land.
The answer to the question as to whether the [*28] effluent detrimentally affected the plaintiff’s land can only be answered after assessing the validity and credibility of the evidence. As I have already said, the evidence of Mr Lawrence on the one hand and Mr Davidson on the other hand amongst the lay witnesses and that of Miss Vincent for the plaintiff and Mr Mackenzie for the defendant were diametrically opposed. I had a view of the locus on the second day of hearing. It was agreed that I should be able to use what I saw on the view as evidence and not merely use it to understand the other evidence. I recorded my impression of what I saw on the view as significant in order to permit counsel to correct any misimpression I may have formed. The notes on the view were shown to counsel for comment, and, after alteration as a result of comment were admitted as Exhibit CX 103.
I realise that I need to be particularly careful about what I saw on the view because the state of the land can vary dramatically depending on the amount of rain it has recently received. I saw the land about three weeks after a minor flood and it may well be that its state in drought conditions is significantly different.
A series of neighbouring land holders [*29] gave evidence. Some said that they had no problem with their land. Some sided with the plaintiff and some with the defendant. Some merely gave evidence as to the going rates for agistment. I have already reviewed some of this evidence. This evidence generally to my mind reinforces the plaintiff’s assertions.
The plaintiff was cross-examined for over a day. He was very careful in making sure he understood the question before he answered. He listened attentively to the questions. He persistently requested Mr Murphy who was cross-examining for further details or definitions. However he did this to such a degree that suspicions arose during the first afternoon as to his bona fides. Was he just an ultra cautious witness or was he using the device of asking for more detail to evade questions? suspect the latter to be the case. This suspicion was reinforced when on one occasion I became a little exasperated and told Mr Lawrence just to answer the question about how high the tidemark was on the creek bank. He gave the extraordinary answer that it was about three metres above the usual water level. This was extraordinary as the only scientific evidence showed that the tidal effect was probably [*30] no more than 0.5 of a metre at the relevant spot. The plaintiff also gave some rather peculiar evidence at the end of the first afternoon. He admitted that, in normal times, when the creek was 15 metres wide, the volume of effluent as compared to the volume of natural ground and rain water was minor. He tried unsuccessfully to seek to evade the significance of this admission by diverting his hearers to considered abnormal times.
There was further bizarre evidence of the plaintiff that the creek rose abnormally depending on the toilet habits of the people of Kempsey. He said that he thought that because so many people arose, showered, went to the toilet and washed their dishes about the same time in the morning, there was a rising of the water level in the creek a corresponding time later (T 59). In view of the fact that there was a 20 day holding pond interposed between the water users and the creek, this was most unlikely. I thought that some of the bizarre evidence came about because Mr Lawrence hated the council officers (the feeling was probably mutual) and thought that he was being clever by giving these bizarre answers to Mr Murphy to whom the plaintiff seemed to take an [*31] instant dislike. I thought that some of the answers and the repeated requests for definition were designed to put the “city slicker” briefed by the hated council off his line rather than to mislead me.
Perhaps the most bizarre piece of evidence came at the very end of the plaintiff’s cross-examination where he did not dispute that he had told a public official that he could not read or write, that he had Alzheimer’s disease and asked whether he could have a document made out in a pseudonym and sign it as a marksman.
I formed the view that I could not completely accept the plaintiff in every detail. Indeed I am fairly sure that he exaggerated the impact on his land of what the council did. He also exaggerated the carrying capacity of his land. I make further reference to these exaggerations in sections F and M of these reasons.
Further I consider that the plaintiff was a witness who genuinely talked himself into believing in his case and he was not going to let anyone else dissuade him from that belief, even by scientific expertise. However, despite these misgivings I generally accept the plaintiff’s evidence as to the state of his land. Although the plaintiff’s evidence [*32] is important, his case depends more on the acceptability of the expert evidence than on his own testimony.
I have already referred to Miss Julia Vincent who gave expert evidence for the plaintiff.
Miss Vincent gave her principal qualification as a Bachelor of Applied Science (Systems Agriculture) from Hawkesbury Agricultural College. This qualification was really a very basic one. Miss Vincent’s summary assessment of the plaintiff’s property in her report of 11 March 1993 is: “The all year carrying capacity of this property in its current condition would be around twelve (12) head. Carrying capacity of this property, now compared with other Macleay Valley properties in similar positions, is poor. Soil tests show marked increases of soil nutrients despite no fertilizers being applied. Many of these elements appear to be at toxic levels. The effects of this toxicity on the pastures has severely reduced the carrying capacity. Christmas Creek has a serious weed infestation which causes prolonged inundation, by flood waters carrying effluent from the sewerage treatment works.” She took soil samples and had them analysed. Her view was that there were very marked differences between [*33] the results of the tests taken above Point Z which she said “are normal on unimproved soil in this area and the abnormally high results obtained from the samples taken from below the discharge point where no fertilizer has been applied.”
The samples were collected by Mr Lawrence in Miss Vincent’s presence. He later pointed out the positions from which he had taken the samples to Mr Mackenzie who took further samples from these positions. Mr Mackenzie sent the samples to a different laboratory to that used by Miss Vincent. Unfortunately these laboratories appear to use different measurement scales so it was difficult to correlate their findings.
Mr Mackenzie failed to find any evidence of nutrient accumulation, toxicity or other damage that he could attribute to effluent.
Miss Vincent was cross-examined for some time. As I have said, she was obviously not the most highly qualified expert in this field. Further, primarily because the plaintiff was not a man with a great amount of spare money to spend on litigation, Miss Vincent allowed Mr Lawrence himself to collect some evidence and often just acted on his say so. However, Mr Lawrence gave evidence and attested to what he [*34] had done and the cross-examination did not affect his evidence. Miss Vincent gave me the impression in the witness box that she was very competent in the field. She answered questions without hesitation and was not affected by cross-examination. Indeed there was, when one analyses it, very little challenge in cross-examination to what she said.
Miss Vincent depended considerably on Mr Lawrence for her “history”. As Mr Lawrence is a little unreliable so must some of Miss Vincent’s evidence be discounted. However, generally speaking, I thought that she was an impressive witness whose views should be accepted.
On the defendant’s side, Mr Davidson, the defendant’s Shire Engineer, now holding the office of Director of Operations gave evidence. Strangely, I was not told what, if any, qualifications, Mr Davidson possessed. He had, however, been the Shire Engineer for the defendant or one of its predecessors since 1972 and the evidence showed he had had some training for this position.
Mr Davidson’s basic position was that everything was all right and that the council had acted in a proper manner and in accordance with the state of knowledge at the time. He was cross-examined on [*35] the correspondence with the State Pollution Control Commission (the SPCC). This correspondence showed that there had been complaints about the effluent in the creek both from the plaintiff and other landowners since at least 1980.
In its letter to the defendant of 4 February, 1981, the SPCC had indicated that its tests showed that some sections of Christmas Creek were anaerobic and that the creek was not considered to be in a good condition and contained some vigorous clumps of water hyacinth. The Minister wrote to the plaintiff in the same month noting that regular sampling of the effluent in the creek had not been carried out and that monitoring work required of the defendant had not been carried out. Furthermore the council was having difficulty achieving the effluent quality required. However, by 1984, the SPCC seemed to have conceded that because of cost and other factors, discharge into Christmas Creek should be licensed.
Judell, Platt, Thomas and Associates Pty Ltd to which I will refer simply as Judell Platt reported to the defendant in February, 1985, “The elevation of the pH in the creek effluent discharge point is attributed to the alkalinity of entering effluent. [*36]
It has been reported that cows will not drink enough water if it contains high concentrations of iron and the content of 4.0 to 8.6 mg/l of iron in the creek may have an effect on stock watering.
The elevation of iron concentration in the water at Kemp Street is attributed to the suspended material containing precipitated iron.”
Kemp Street is to the East of the plaintiff’s property. Kemp Street runs into Saleyards Road at a low bridge over the creek. Judell Platt’s report showed that the iron at Kemp Street was 8.6 as opposed to 4.0 upstream of the effluent discharge, non-filtrable residue 370 as opposed to 80, total alkalinity 84 as opposed to 59 and total hardness 87 as opposed to 48. Mr Davidson in cross-examination agreed that the SPCC required that before the defendant irrigated land on which a beast was to graze with effluent it had to be held in a holding pond for 20 days. Mr Davidson, however, considered that so long as the effluent just passed into a waterway it could hardly get onto grazing land except by pump irrigation so that the condition did not apply.
It T 321, Mr Cotman asked Mr Davidson: “Q. So I take it you would have discouraged pump irrigation from [*37] Christmas Creek below the discharge point because that would contravene SPCC requirement, is that right? A. No….Because pumping out of Christmas Creek in the vicinity or anywhere on the other side of the railway bridge is fine. It is tidal. ……….. Q. And at times of low water flow and irrigation might be sought, the flow was substantially from flows of effluent, wasn’t it? A. Yes. Q. And to irrigate onto pasture for cattle consumption would, as you understood it, have contravened SPCC requirements? A. I’m not sure about that. … Q. But as you understood the situation in 1981 the SPCC was saying to you in relation to the effluent you were discharging, this effluent should not be used for irrigation of pastures used for cattle grazing? A. That’s correct.” Mr Davidson then agreed that if people pumped from the creek for cattle grazing purposes that would be a breach of SPCC requirements, but said that that was a matter for the SPCC.
Mr Davidson seemed to be completely unaware until June 1985 that the introduction of nutrients including nitrogen and phosphorus would be a problem. He admitted, however, that in 1981 the SPCC had called attention to the undesirability of waste [*38] discharge into small rivers and streams. He says his concern was with algae and aquatic weeds.
The SPCC’s letter to the council of 26 June, 1985 included an expression of concern as to the nutrients that were passing into the creek and the Macleay River and indicating that steps would have to be taken to improve the water quality. It pointed out that the nutrients were causing the growth of large tracts of water weeds including some noxious varieties. SPCC advised against the use of the creek for domestic water or recreational use, but thought that there was no need to restrict other beneficial uses of the water.
There is no doubt that Mr Davidson appreciated right from the commencement of the diversion of the entry point of the effluent to Point Z that the creek would contain considerably more liquid upstream of Point Y than previously. However he appeared not to have foreseen any problem with the extra water. Earlier cross-examination went to the point that in 1980, Mr Davidson had said that, “Council should continue to control aquatic weeds on Christmas Creek and reduce the nuisance as much as possible by confining the flow to the bed of the creek.”
Mr Davidson at that [*39] time, and may still, held the view that so long as the polluted water stayed in the creek, the only problem was with aquatic weeds. He further felt that the way to control those weeds was with chemical treatment. He did not seem to appreciate that poisoned weed might well sink and block and poison the creek. Mr Lawrence opposed chemical treatment, and this led Mr Davidson to think even less of Mr Lawrence.
At T 312 the following cross-examination took place: “Q. You then went on to say ‘Council should continue to control aquatic weeds on Christmas Creek and reduce the nuisance as much as possible by confining the flow to the beds of the creek’? A. Yes. Q. What did you understand by that turn of phrase ‘Confining the flow to the bed of the creek’? A. By eliminating some of the blockages in the general area. Q. The creek might flow more freely? A. Well, by removing the blockage the level of the creek would be lower and its width would be confined. Q. It would not tend to flow over its banks and onto the adjoining land, is that right? A. Well, my essential aim was to reduce the level of the water to thereby narrow the width of the channel that was occupied by water. That meant a relatively [*40] small cut in any obstruction. Q. But your purpose was to attempt to confine the flow to the bed of the creek, wasn’t it? A. It was my perceived view that if we could narrow the width of the water from about 15 metres, any reduction would make management of the weed much easier. Q. But here on 29 you are talking simply about the control of aquatic weed, aren’t you? A. Yes. Q. Not about cutting creeks. It’s the control of aquatic weed? A. Yes. Q. You understood that uncontrolled aquatic weed was causing the creek not to be confined to the bed of the creek? A. No. My concern there was that we had a management problem that involved a length of creek about 15 metres wide that could be reduced markedly by some adjustment to the bed of the creek. ……… Q. Now you suggest that the council should continue to control aquatic weed on Christmas Creek and reduce the nuisance as much as possible? A. Yes. Q. By confining the flow in the bed of the creek? A. Yes. Q. You understood there was a nuisance being created by the flow not being confined to the bed of the creek, didn’t you? A. No. The nuisance was the propagation of water hyacinth.” Mr Cotman put that Mr Davidson’s answers are a little [*41] disingenuous in relation to his understanding of the effect on creek blockage on the creek water escaping the banks of the creek. His note, on which he was being cross examined, speaks in clear terms as to the appreciation of the risk of unconfined flow of the creek, ie an escape of water that would necessarily flow to the low land adjoining the creek on, inter alia, Mr Lawrence’s land. Drains and the like would be ineffectual because, by definition, the creek waters were higher than the land that would require draining. Drains would bring the inundation, not remove it.
Mr Davidson was not the most impressive of witnesses. He tended not to address the questions put to him, but to make speeches. I think this was more because, as a person in authority, he was more used to telling people things rather than having to listen to questions and answer them. Thus, I do not consider he was prevaricating at all. Indeed, I got the impression that he was a man who knew that his practical way of doing things was correct and was not at all concerned with extraneous matters such as pollution or the plaintiff’s rights. He had to do a job to disperse part of the sewerage effluent of the Town of [*42] Kempsey as cheaply as possible and he did not allow other matters to cloud the issue. The defendant also called on hydrologist Dr Stephen Webb. I have already briefly referred to some of his evidence. I deal with the inadmissibility of his evidence from computer flood modelling in Section M of these reasons. His remaining evidence was of a technical nature and was more relevant to high flood conditions than to the low flooding problem that is to the core of this case.
Dr Webb commented adversely on the evidence given by Mr King, a Civil Engineer, called for the plaintiff. I do not consider that discussion or resolution of their differences would assist in the determination of the real issues in this case. Indeed Mr King’s evidence was mainly relevant only to the side issue as to whether the council’s method of performing its functions was the only way of performing them.
Mr Mackenzie finally appeared on the last day of the hearing. He said that he had been involved in giving evidence before some administrative tribunal in Canberra and was not able to be in court when he had been scheduled to give evidence in this case. Three factors tell against Mr Mackenzie’s evidence being [*43] accepted. First, it was clear to me from the view that the plaintiff’s property near the creek was far more deleteriously affected by bogging, smartweed and rushes than surrounding properties. Secondly, the scientific analysis of the water samples from Judell Platt show that the substances which were pouring into the creek, are substances which the SPCC branded as being harmful to domestic and recreational users of the creek and to cattle that might graze upon it. Thirdly, the warnings of the SPCC would seem to have been otiose if nothing harmful was happening.
As I have already said, Miss Vincent’s evidence clearly shows a considerable detriment to the plaintiff’s land by the inundation. Mr Mackenzie would have me believe that conditions on the plaintiff’s land near the creek are just the same as on similar land in the vicinity, so that the effluent has nil effect.
I find it impossible to accept the defendant’s basic premise that there is no difference to the plaintiff’s land from neighbouring land other than that caused by bad husbandry. The plaintiff’s land is good drought fodder land which has to the naked eye been affected by the smartweed and the growing of rushes etc [*44] in the area where ponding has taken place after minor flooding.
A lot of time was spent in this case over the water hyacinth growth. This was not a problem at the time of the view, because there had been some major flooding and the water hyacinth had been washed away. The increased growth of water hyacinth did not directly cause the plaintiff damage. However, the presence of water hyacinth blockages from time to time exacerbated the problems with minor flooding to the plaintiff’s land. I do not accept the defendant’s view that the water hyacinth merely floats on top of the water relatively harmlessly and does not contribute to flooding at all. That might be true of a major flood, but, as has already been seen, it was the effect of a series of minor floods leaving ponded effluent on the plaintiff’s land which was the most significant problem.
On the other side of the case I must say that my view is that the plaintiff has overstated the position when he says that the native grasses have been destroyed. There was some confusion between the various experts as to what was an Australian Native Grass as opposed to grasses that at some stage in our history had been imported from the [*45] Northern hemisphere. It does not seem to me that this matters very much. I am convinced that some of the species of grass that were on the property when the plaintiff acquired it still remain on the property. I am also convinced that a significant amount of good fodder grass has been destroyed by the effect of effluent polluted water overflowing onto the grasslands.
Mr Murphy submitted that there was no acceptable evidence that the banks became saturated or that the cattle became bogged. He put that the plaintiff did not live on the property and did not observe the rise and fall of the water in the channel. However, there is nothing to tell against me accepting the plaintiff’s own evidence that he had to rescue bogged cattle from time to time and that of Mr Brady. I do accept that evidence. Accordingly, I consider that I should basically accept the evidence of the plaintiff and of Miss Vincent that there was a deleterious effect to the plaintiff’s land as a result of the defendant’s activities. However, the effect was not quite as serious as the plaintiff paints it.
F. Although mitigation of damage was not a phrase which ever escaped Mr Murphy’s lips, the defendant’s case was [*46] that if anything operated to diminish the productivity of Mr Lawrence’s land, it was not any effect of the effluent, but rather the plaintiff’s bad husbandry.
I have already commented on the plaintiff’s credibility. I should add that I consider that the plaintiff is one of those farmers and graziers one meets from time to time who, when external forces do something to change the environment, blame all deleterious happenings on that change. It also seemed apparent that some of the deleterious effect of the effluent, if there was any, could have been readily neutralised. Thus the bogging problem could have been fixed by connecting to the town water supply about five years earlier than in fact occurred. When this connection was made, the cost was only about $ 4,000. However, the plaintiff could not see why he should mitigate his damage. He saw matters simply that the defendant had injured his land and that the rights of the matter were that the defendant must fix it. He was not going to stop himself being injured by the defendant’s activities by spending a little money to help himself. He could not see and still cannot see why he should do so. On the other hand, it must be realised [*47] that there was no real use in attending to remedial measures until the source of the problem had been fixed. There was some suggestion that Mr Lawrence should have been slashing his smartweed. I do not think that, on the evidence this would have caused more than cosmetic changes to the property. So long as the nutrient enriched effluent was coming down the creek and minor flooding was taking the water from time to time through depressions in the cusp to pond in lowlands beyond the cusp, there was little that even the most conscientious farmer could have done about alleviating the problem.
G. Mr Cotman submits that any reasonable person would foresee that the process by which inundating water would carry weed seed over that land was preventable. Such a person would foresee that such water may well contain effluent with a high nutrient content that would work changes to the soils that might well both kill the native pastures and promote the growth of the weeds on Mr Lawrence’s land. Thus he puts that apart from any question of whether the effluent discharge could be disposed of elsewhere, what was in the discharge, and the weed growth associated with the discharge, and the propagation [*48] of those weeds, were all matters that could have been addressed to ameliorate the consequences of the effluent discharge on to Mr Lawrence’s land. It certainly appears clearly from the evidence that the council was aware in 1981 that disposal into a water- way, particularly a small one, was not a “preferred” method of disposal and that land based disposal was the preferred method. It was reminded of that fact in 1982, but did nothing about it. It did not take any steps to acquire 70 hectares of land to undertake the land disposal of effluent for the next thirteen years until the acquisition of Mr Griffin’s land for a relatively modest sum. It was only then that the council undertook land disposal of effluent.
H. I now pass to the defences that the defendant has because it is a statutory authority carrying out authorised works. As I read the authorities, this part of the case has been characterised in two slightly different ways. First it is sometimes said, see Van Son’s case at 32 that if a defendant was acting in accordance with its statutory rights and duties, it cannot be said that there was any unreasonable act on its part for the purpose of establishing nuisance. Secondly [*49] it is sometimes said that, absent an express or implied right to create a particular nuisance, a council may be liable in damages and susceptible to an injunction for creating a nuisance in the exercise of a statutory power or the performance of a statutory duty, notwithstanding the statutory power to perform that function, if it is not necessary to create the nuisance in order to exercise the statutory power: Carden v Kuringai MC (1932) 10 LGR 162. Whichever way the proposition is put, it is clear that for all practical purposes, a local authority is given a measure of protection against liability for nuisance as a result of exercising its statutory powers. However, as Mr Cotman has submitted, the nuisance must be the “inevitable consequence” of the performance of the statutory duty or exercise of power to be justified by the statute: York Bros v Commissioner for Main Roads 1983 1 NSWLR 391 at 397.
In the York Bros case, Powell, J held at 398 that “inevitable consequence” means that there was in light of contemporary scientific knowledge, no reasonable way the permitted function could be performed without causing the damage.
Unnecessary creation of a nuisance is clearly [*50] demonstrated where the power to prevent the nuisance lies unexercised in the hands of a council, see Carmichael v Sutherland Shire (1972) 25 LGRA 435 at 445-447 and the York Bros case. Further, the authorities establish that a council must exercise reasonable care in the exercise of the power: Edwards v Blue Mountains CC (1961) 77 WN (NSW) 864; 6 LGRA 264, Essendon Corp v McSweeney (1914) 17 CLR 524; Samways v Sutherland MC (1932) 11 LGR 41.
In Carmichael’s case the facts were that the council’s road works concentrated extra volumes of water into a natural watercourse which had the effect of flooding the plaintiff’s land. Helsham, J found that, although the council was carrying out a statutory function, there was no statutory authorisation of the act of nuisance it had committed and that that nuisance could have been avoided if the council had used all proper care. The authorities show what needs to be shown for the council to justify the nuisance created by excluding alternative means of carrying out the activity. As Powell, J said in the York Bros case at 399, the alternative must be “some fantastic method, really quite unsuited [*51] to the object in view, although it might to some extent perform the duty prescribed.” This derives from Provender Millers (Winchester) Ltd v Southampton CC 1944 Ch 131.
In essence the test is, did the council act taking all reasonable regard and care for the interests of other persons? As to this see Allen v Gulf Oil Refining 1981 AC 1001, 1011 and Tate and Lyle Industries v Greater London Council 1983 2 AC 509, 538. Thus, where the power exercised is in the construction of some work, reasonable care must be exercised in the design and execution of the work so that it does not cause harm that might be avoided. Once the works are in place they must be operated with reasonable care.
In Manchester Corp v Farnworth 1930 AC 171, 183, Viscount Dunedin said, “When Parliament has authorised a certain thing to be made or done in a certain place, there can be no action for nuisance caused by the making or doing of that thing if the nuisance is the inevitable result of the making or doing so authorised. The onus of proving the result is inevitable is on those who wish to escape liability for nuisance, but the criterion of inevitability is not what is theoretically possible [*52] but what is possible according to the state of scientific knowledge at the time, having also in view a certain common sense appreciation, which cannot be rigidly defined, of practical feasibility in view of situation and of expense.” In Rudd v Hornsby SC (1972) 31 LGRA 120, Holland J accepted the law as stated in the passage I have set out and then made it clear that the simple cost equation propounded by the defendant is inadequate to the task of balancing the respective interests involved. His Honour pointed out (at 139) that it would hardly be reasonable that the plaintiff bear the burden of a drainage system that benefited the ratepayers provided with the drainage service without making a comparison between the cost of providing that benefit and the damage to the plaintiff.
Mr Cotman submits that, on the evidence, aspects of the damage done to the plaintiff’s land cannot be even remotely considered a necessary consequence of the operation of a sewage works or the discharge of effluent from such works. The damage was in fact consequential, but it was a consequence that was avoidable at the most elementary level. Mr Cotman says that the creation and maintenance of a source (the [*53] discharge channel, both old and new) for the dissemination of weeds or their seeds into the waterway of the creek and over the adjoining lands was, on the council’s own case, avoidable. On the council’s own case it was merely a land management problem. The infestation of the creek banks or creek waters themselves with weed, initially the hyacinth and later the hyacinth and smartweed, is and has always been both preventable and avoidable. The defendant sought to say that its method of carrying out its statutory powers was the only cost effective method of doing the work. Doubtless it was cheaper to let the effluent flow into Christmas Creek, but cost was not the only factor to be taken into account.
I do not consider that on the evidence, the defendant has shown that damage to the plaintiff’s land was an inevitable consequence of it performing its statutory functions. The land irrigation scheme implemented in 1993 shows that there were available ways of carrying out the statutory function which interfered much less with the plaintiff’s land. In my view, the defendant has not made out this defence.
I. S733 of the Local Government Act, 1993 provides, so far as is relevant, as [*54] follows: “733(1) A council does not incur any liability in respect of: ….. (b) anything done or omitted to be done in good faith by the council in so far as it relates to the likelihood of land being flooded or the nature or extent of such flooding.” S733(3) provides examples of matters included within the generality of subs1 and subs2 and lists inter alia, “(e) the carrying out of flood mitigation works; … (g) any other thing done or omitted to be done in the exercise of a council’s function under this or any other Act.”
S582A of the Local Government Act, 1919 which was enacted in 1985, but given retrospective operation was in precisely similar form except in relation to coastline hazards.
Mr Murphy submits that the decision of Rolfe,J in Bennett v Water Administration Ministerial Corp (6 June, 1991, unreported) must lead to the result that, no matter what otherwise might be the case, there must be a verdict for the defendant.
In Bennett’s case, Rolfe, J tried a preliminary issue involving the construction of this section. The facts of Bennett’s case as set out in the Appendix to that judgment are that the plaintiffs complained of flooding due to negligent design and [*55] construction of irrigation channels by the defendant. The land flooded was flood liable land. Rolfe, J said at 7, “The building of irrigation channels, work subsidiary to that, the installation of equipment in and for such channels and the maintenance thereafter of the channels and installations, were all things ‘done or omitted to be done’ by the Defendant. The bringing, by artificial means, of water on to land, constitutes, in my opinion, the likelihood of land being flooded as a result of that which is done or not done. There are numerous ways one may hypothesise this happening, eg the banks containing the water may fail, the water in the channels may rise above the banks following an unexpected influx of water into the system, and equipment and installations for controlling the water in the channels may fail, notwithstanding the existence of good faith. In any of these circumstances surrounding land may be, and probably will be, flooded. Thus, the thing done or omitted to be done by the Defendant, within the relevant purpose, is something from the liability for which it is protected. “I pause here to observe that no submission was made, and I can well understand why, that the [*56] protection did not extend beyond ‘the likelihood of land being flooded’, ie it did not extend to protection from the actual flooding. If the section were intended to have that meaning the Defendant would be protected, notwithstanding there was no flooding and, hence, notwithstanding there was no damage. The legislation was obviously intended to serve a purpose. If I were to give it this interpretation I cannot see what that purpose would be. For these reasons I appreciate why Mr Darvall made no such submission. In this regard some reliance may be placed on Exhibit ‘A’. “However, this does point up another matter, which, in my opinion, favours the construction contended for by the Defendant. If the subsection were intended to relate to flood mitigation work, one would expect it to say words to the effect ‘of land not being flooded’. Obviously the legislature contemplated that as a result of an act or omission by the Defendant, inter alios, there would be a likelihood of land being flooded or being flooded differently or to a greater, or perhaps lesser, extent than before the act or omission. It was against that act or omission that the statute gives protection to the Defendant.”
It should be noted that an appeal was lodged against Rolfe, J’s decision, but the appeal was subsequently dismissed by consent.
Mr Murphy submits that the plaintiff’s allegations as to nutrients being flooded onto his land and water hyacinth causing flooding or smartweed seeds being flooded onto his land are all allegations that “relate to the likelihood of land being flooded or the nature or extent of any such flooding.” Thus, he submits, if those allegations are, contrary to his submissions, established, the council relies on the statute to protect it.
It seems tolerably clear that one of the main motivating factors for enacting the predecessor of s733 in 1985 was the realisation of the large potential liability on local councils following, L Shaddock and Assoc Pty Ltd v Parramatta City Council (1981) 150 CLR 225 linked with the fact that there had been a considerable number of development approvals given in respect of land which was in the plain of 50 and 100 year floods, see Butterworth’s Conveyancing Service Vol 1 10843 . However, the protection to councils was taken further than protection from the giving of advice or approvals to things [*58] which were done or omitted relating to flooding or potential flooding. Rolfe, J construed the section in a very wide way.
To follow that interpretation would virtually absolve a council from liability for any negligence, nuisance, breach of statutory duty or the like so long as the work done or omitted from being done related to flooding. It might even prevent workers on flood mitigation work being able to sue for personal injury suffered whilst employed in an unsafe system of work on such a project. That would be a strange result.
It is a basic principle of construction that one construes statutes in such a way that unless the opposite is clearly stated, there is a presumption that the legislature intended to depart from the common law as little as possible, Arthur v Bokenham (1708) 11 Mod 148, 150; 88 ER 957, 958; Maxwell on the Interpretation of Statutes, 12th ed (1969) at 116-123.
The matter being of some doubt, when one looks at the Minister’s Second Reading Speech (Mr Carr, Hansard for 16 April, 1985 at 6023-6026) one can see no such intention. The purpose of the measure was to allow councils to approve of development [*59] in land that might be affected by flood on a greater frequency of one in 100 years, by laying down guidelines in a manual and then protecting councils from liability if they observed the manual. The Hon Mr Hallam in giving the Second Reading Speech in the Legislative Council (Hansard, 22 April, 1985, 6563-6565) actually said at 6565, with reference to what is now s733, that the section “provides for such protection subject to those protected having acted in good faith being that they must have acted substantially in accordance with government policy at the time as recorded in the flood liable land manual. That is, responsible actions will be protected and irresponsible actions will not be protected by this legislation.” One can see reference to the manual in s733(5). Apart from the problem exposed in Shaddock’s case, it is difficult to see the need for s733. As has been seen under section H of these reasons, councils were already protected against liability for works done which caused damage provided that the council could show that the damage was the inevitable consequence of the statutory task being done.
In my view s733 of the Local Government Act, 1993 only applies to advice [*60] given or work done when a council is carrying out government policy in relation to flood-prone lands. It does not apply to all works done which might cause land to be flooded. Another way of reaching the same result is to say that the words “good faith” in s733(1) and s733(2) focus primarily (though not exclusively, vide s733(4)) on compliance with government policy manuals. It is not enough for a council relying on the statutory defence under the section to say that there is no evidence that it has acted other than honestly. It must show that it has acted in accordance with government flood control policy. The council in the instant case, has not shown this to be the case.
I realize that this approach runs contrary to the assumption made by Rolfe, J. I also realize that s733 including the term “bona fide” is in a common form, see eg Larkin v Capricornia Electricity Board 1995 1 QdR 268. However it seems to me that the proper construction of the present section requires “bona fide” to be given this special meaning.
Accordingly, the defence under the section, fails.
J. S33 of the Drainage Act, 1939, so far as is relevant, provides as follows: “33(1) A board or any person [*61] authorised by it may enter any land … for the purpose of … constructing … the works …
(2) The board shall make full compensation for damage occasioned to any land in the exercise of its powers and duties under this Act.
Any claim for compensation shall be lodged with the board not later than six months after the date upon which the owner of the land becomes aware that such damage was occasioned.” Although this defence was trumpeted loudly by the defendant at the directions hearing, it was not emphasised during the oral hearing until addresses.
Mr Murphy submitted that there is no doubt that there was a written agreement dated 15 June, 1982 between the defendant council and the directors of the Glenrock-Tennessee Drainage Union whereby the council was, at the request of the Drainage Union, to carry out the work there defined. That work included the work at the commencement of Period C. The agreement provided that the drains would remain the property of the Drainage Union and that the union would indemnify the council against actions arising from the drains.
The Drainage Union contributed $ 400 towards the total cost of the work which was estimated at $ 10,000. [*62] The facts do not bear out the contention that the project of deepening the creek in 1986 was inspired by the Glenrock-Tennessee Drainage Union. The evidence shows that at all times it was the council’s project and the introduction of the Drainage Union was simply to obtain a contribution towards its cost.
Mr Murphy acknowledged that the NSW and Commonwealth governments in fact subsidised the bulk of the cost. Of the 20 per cent that remained, Mr Murphy puts that it is an insignificant factor that the council paid the greater proportion. He also downplays the fact that the plans were prepared by or under the aegis of the council or its predecessor. Mr Cotman merely put that, when one looks at the whole picture and sees who prepared the plans, who directed the work, who paid for it and who maintained it, it can easily be seen that the work was the council’s, not the Drainage Union’s. He also strongly relies upon a letter dated 23 June, 1982 from the defendant council to the plaintiff’s then solicitors. This letter reads, omitting formal parts, “The Council is responsible for the disposal of sewerage effluent within the Shire district. Under licence from State Pollution Control Commission [*63] sewerage effluent is discharged into Christmas Creek. As a matter of physics and hygiene it is an impossible task to cease the flow of effluent into the creek.
The Council is presently undertaking drainage works in Christmas Creek pursuant to powers conferred under the Drainage Act, 1939. The Council intends to continue this work and acknowledges its responsibility to compensate for any damage occasioned to any lands in the exercise of its powers and duties under the Act.”
The question is, Who did the work? Was it the council as agent for the Drainage Union? Was it the council in its own right?
Whilst, like many questions which come before this court, there is some material each way, the preponderance of the evidence is that the whole project was planned by the council and was carried out under the control of the council on its own behalf. Thus, the defence under s33 does not avail the council.
I should note that there was some discussion as to whether the council was the agent for the Drainage Union and, if so, whether a corporation such as a council could come within the expression, “any person authorised” as used in s33. Mr Murphy relied on Shoreline Currencies (Aust) [*64] Pty Ltd v Corporate Affairs Commission (1986) 11 NSWLR 22, 36 to base his submission on, that one must seek to find what the section intended to cover.
As I have found the facts, this question does not arise. However, I should state that whilst the word “person” often includes “corporation”, I do not think it does in the instant section. It seems to me that the authorised person is the person who actually does the physical work authorised by the Board and not some intermediate bureaucratic authority.
K. Because of the decision made in s1, the question as to whether the letter of 23 June, 1982 set out in that section operated as an estoppel does not arise.
L. The question arises as to what remedies the plaintiff is entitled as a result of these findings? The plaintiff asks for damages and injunctions. The damages are sought under a series of headings which are contained in the plaintiff’s submissions MI 113. As to injunction, the work done by the council in 1993, well after the proceedings were commenced, means that it is not as necessary to grant an injunction as previously. However, Mr Cotman says that his client is entitled to an injunction, perhaps a Common Law Injunction, [*65] to ensure that the defendant continues to keep to the standards set by the anti pollution authorities.
Common Law Injunctions are described in Astor Electronics Pty Ltd v Japan Electron Optics Laboratory Co Ltd 1966 2 NSWR 419. They enable a court which has determined that a breach of a common law right has occurred to grant an injunction to prevent continuation of the breach. This power is in addition to the court’s power in its equitable jurisdiction to grant an injunction in aid of an equitable right.
The court does not lightly grant injunctions. It does not grant injunctions merely to make the plaintiff feel more comfortable. It usually only grants injunctions where there is a real threat that, without an injunction, the plaintiff is likely to suffer irreparable damage. In the instant case, in the light of the land irrigation work done in 1993 and in the light of the fact that the defendant is a public authority which is likely to abide by the decision of a court, I cannot perceive any such threat. Thus, I decline to grant any injunction. The plaintiff is entitled to damages. M. As to the quantum of the plaintiff’s damages, I have reviewed a considerable amount of the [*66] evidentiary material in Section E of these reasons. Essentially Miss Vincent and Mr Lawrence say that in a very dry year the land carried 150-170 head of cattle and 10-12 horses. Its year round carrying capacity in ordinary conditions would be about 70 head (T 241).
Mr Cotman submits that if this evidence is accepted, the loss of capacity of the plaintiff’s land is, as to 40 hectares, 20 animals per annum (40×1/2), and as to the remaining 70 hectares, 35 animals per annum 70×1/2=35- (70×1/3)+12 . The aggregate year round loss of capacity in average conditions is at least 32 head. He further says that what is also lost to Mr Lawrence is the drought proof paddock benefit, that the land had, that allowed up to 200 animals to be kept in bad drought on the low-land wet pasture, such as in 1940. He says that in effect, the wet state of the land has become a source of its problems in that it encourages the growth of weed. What was a virtue is now a vice.
In addition, Mr Cotman says that the plaintiff is entitled to the ongoing costs of operating a property still exposed to inundation, including the cost of ongoing vigilance required to protect cattle from the creek beds. Then, [*67] he says, the “experts” recommend that the land be drained, be replanted with new pasture, re-fenced and generally converted from the property it was into a new property. That will cost money to do. Miss Vincent estimates the cost at $ 16,800 for the first year with an ongoing loss of production while that occurs and extra costs of $ 1,000 per year thereafter. If that work is not done, there is a loss of capital value estimated by Mr Noble at $ 60,000.
Mr Murphy argues that if the court accepts that the plaintiff has suffered some loss, that loss is either the loss of value of the land, should the plaintiff sell it or, alternatively, the loss of income while it is rehabilitated, plus the cost of rehabilitation plus past lost income. He says to compensate the plaintiff on the basis suggested by Mr Cotman involves “double dipping.”
Really the two sets of submissions are not far apart. The normal measure of damages for nuisance causing damage to land is the diminution in value of the land, Ward v Cannock Chase DC 1986 Ch 546, 575-577, but, where the plaintiff is acting reasonably in seeking reinstatement, the court may consider that it is more appropriate to assess the damages [*68] on the reinstalment basis, Ward’s case and Parramatta City Council v Lutz (1988) 12 NSWLR 293.
In the instant case, it seems to me that the reinstatement method is more appropriate. This case concerns vacant grazing land. The cost of reinstatement at the proper time will restore the land to its full value. This appears to me to atone more faithfully for the wrong than to take the present-day diminution in value. One must then work out what is the proper date for assessing the plaintiff’s reinstatement costs. The authorities are not all one way (see McGregor on Damages, 15th ed 1400 ), but it would seem that if it was not reasonably worthwhile to do remedial work whilst the cause of the problem still exists, the damages are assessed at a date not earlier than the cessation of the nuisance, Bunclark v Hertfordshire CC 1977 EGD 659. In the present case, it was not until the land irrigation system was implemented in 1993 that the source of the nuisance was dealt with. Thus, in my view, one assesses damages as at 1993-1995; the costs appear to have varied little in that period.
By particulars MI 121, the plaintiff claims approximately $ 175,000 plus general damages. However, [*69] that $ 175,000 includes diminution in value damages of $ 60,000 which, if the land is restored, should not be suffered. It also includes $ 4,000 for connection with the town water supply and $ 5,000 for water consumption. I consider these claims are too remote from the nuisance. Furthermore, there is an element of betterment involved.
I consider that I should allow $ 20,000 for reinstatement, including Miss Vincent’s assessment of $ 16,800. I will allow general damages of $ 10,000.
The other items claimed by Mr Lawrence is decrease of carrying capacity over the period the land was affected. The claim is for $ 42,432 calculated at the rate of a loss of 32 animals per year. There has been little contest about the rate of loss, the contest being whether this loss was caused by the defendant’s actions or merely by poor husbandry. In my view, the balance of the evidence favours the plaintiff on this issue. However, as I have said before in Section C of these reasons, the plaintiff has exaggerated the effect of what the council has done. The evidence suggests that part of the plaintiff’s problem is that his land has suffered from overgrazing. He also tended to exaggerate his losses. [*70] I consider that I should reduce the figure estimated by the plaintiff by 25-30 percent, and will take 23 animals lost as opposed to 32. On this basis, the plaintiff’s loss is $ 37,498.
I should say that I considered that the evidence that the plaintiff could merely slash the smartweed and control it easily was unconvincing. I consider that the loss was suffered and was suffered as a result of the defendant’s wrongful act.
On this basis, I award the plaintiff $ 67,498.
As to interest, having allowed the plaintiff present day rehabilitation costs, the only allowance for interest should be on the $ 37,498. The amount in accordance with the Rules has been worked out by the plaintiff’s solicitor on MI 118 as $ 43,863.28. There has been no quarrel with this calculation. Allowing 23/32 of this sum, the interest component is $ 31,527.
Accordingly there should be a verdict for the plaintiff for $ 99,025. N. I should now deal with the one remaining question which is the evidentiary question I reserved, as to whether a scientist’s computer model of how Christmas Creek would behave under certain conditions, by adopting the course of provisionally admitting the evidence subject to relevance. [*71]
Mr Webb gave evidence that it is difficult to observe flood patterns because floods occur uncommonly and when they do, each flood is unique. Furthermore, even the longest term resident has only been able to observe a small number of the floods that have happened on a particular site during history. It is thus necessary to operate from models if one is to be able to predict flood patterns. Since the 1970s, physical models have been used less and less and have been displaced by what is called “numeric models”, which are computer models.
Dr Webb utilises software called RUBICON. He says that this was developed in the Netherlands. This software according to Dr Webb makes use of mathematical equations “which have been developed and confirmed over many years of experimentation and observation.”
One must be very careful with computer predictions. Usually they are the result of someone making assumptions and assessments of various vital factors and feeding these factors into the comPuter. Unless those assumptions and assessments are proved by evidence (or are conceded to be valid) the mere fact that a computer produced a prediction is of no evidentiary value whatever. It is clear [*72] law that an expert witness’ evidence on matters of fact is in the same position as the factual evidence of any other witness; English Exporters (London) Ltd v Eldonwall Ltd 1973 1 Ch 415, 421; Pownall v Conlan Management Pty Ltd (1995) 16 ACSR 227, 231. That problem cannot be overcome merely by feeding unproved factual material into a computer and treating as evidence what the machine produces.
Thus if one has a computer to predict an election result, one can obtain on a screen a simple graph that will show that after the preferences of minor parties have been counted, there will be a two party preferred vote of 52 per cent for Party A and 48 per cent for Party B. However, this result has only come about because the programmer has fed the computed data such as that there will be a 53 per cent flow of X’s preferences to Party A and 47 percent to Party B. Unless there is some factual evidence or satisfactory expert opinion evidence to support that sort of assumption, the result obtained from the computer has no evidentiary value.
The same reasoning led me to reject evidence of prediction of floods and the extent of flooding by so-called computer models. I should note that [*73] in the ultimate, this rejection did not have any bearing on the result of the litigation.
Counsel for the plaintiff: NA Cotman
Solicitors for the plaintiff: Garrett and Walmsley (Port Macquarie)
Counsel for the defendant: MFF Murphy
Solicitors for the defendant: Sly and Weigall