EASTON AGRICULTURE LIMITED v MANAWATU-WANGANUI REGIONAL COUNCIL HC PMN CIV-2008-454-31

EASTON AGRICULTURE LIMITED v MANAWATU-WANGANUI REGIONAL COUNCIL HC PMN CIV- 2008-454-31 7 September 2011IN THE HIGH COURT OF NEW ZEALANDPALMERSTON NORTH REGISTRYCIV-2008-454-31BETWEEN EASTON AGRICULTURE LIMITEDFirst PlaintiffAND EVELEIGH FARMING COMPANYLIMITED (IN RECEIVERSHIP)Second PlaintiffAND MANAWATU-WANGANUI REGIONALCOUNCILDefendantHearing: 30-31 May, 1-3 June, 7-10 June 2011Counsel: J O Upton QC with M S Dobson for PlaintiffsD J Heaney SC with S H Macky for DefendantJudgment: 7 September 2011JUDGMENT OF THE HON JUSTICE KÓSIntroduction [1]Background [5]The February 2004 flood [36]Parties [67]Pleadings [76]Issues [93]Issue 1: Can the Council be liable other than in negligence? [94]Issue 2: Did the Council owe the plaintiffs a duty of care in its monitoringand maintenance of the stopbank? [122]Issue 3: Was the Council negligent? [143]Issue 4: Did the Council's negligence cause the plaintiffs' loss? [195]Conclusion [224]Disposition [225]___________________________________________________________________Introduction[1] A floodway stopbank fails. The floodway diverts part of a river's flow duringflood conditions. Together the floodway and river can cope with a 1 in 100 year flood. But the flood that leads to the stopbank failure is greater still. A 1 in 110 year flood. The floodway is crossed by a highway bridge. The bridge cuts through the top of the stopbank on the southern side of the floodway. During the flood the water reaches and laps the bottom of the bridge. Yet the flood should still be able to be contained within the floodway stopbanks.[2] But the southern stopbank fails. First, just upstream of the bridge. Then, a few hours later, downstream of the bridge. Ultimately a gap of 40 metres opens up about the bridge. The exact cause of the failure is in dispute. Nearby croplands belonging to the plaintiffs are flooded. The stopbank is the responsibility of a regional council. Must the council compensate the plaintiffs for the loss of their crops?[3] The main questions in this case are whether the Council was negligent in its monitoring and maintenance of the stopbank, and whether any such negligencecaused the plaintiffs' loss. The plaintiffs expressly do not claim the construction of the bank or bridge was negligent.1 Any such claims would long since have been time barred.[4] Evidence as to quantum was received by the Court. By agreement the issue of quantum was reserved for further argument, if need be. This judgment is confined to whether the Council is liable to the plaintiffs.BackgroundManawatu River[5] The Manawatu River is about 160 kilometres long. It rises on the eastern side of the Ruahine Ranges. Fifty kilometres later it passes through the Manawatu1 This was made clear in the plaintiff's closing submissions: see [81] below.Gorge, and then flows on past the city of Palmerston North. From there to the small settlement of Opiki, the river is steep enough to transport gravel when the river is in flood, and the riverbed is gravelled. Downstream of Opiki the gradient is flat. The riverbed is silty. Flood velocities here are typically about 1.5 metres per second, compared to 3 to 4 metres per second in the steeper Palmerston North section.[6] River level and flow records have been held longer for the Manawatu than any other river in New Zealand. An automatic recorder has been operating at Palmerston North since 1929. Manual information is available back to the 19thcentury. The February 2004 flood, with which we are concerned, was the third largest flow recorded on the river:Year Discharge (cumecs)21880 40001982 38002004 3500[7] At Opiki, where the river gradient flattens out, the Oroua River joins theManawatu. The Oroua is the Manawatu's major tributary. Below the confluencewith the Orua, at Opiki, the Manawatu wends its way on towards the sea past flat lands called the Makerua and Moutoa basins. The plaintiffs farm in the Moutoa basin.[8] Substantial swamp drainage works were undertaken in these areas in the 19thcentury. Flax was planted in the newly drained land. The flax fibre was used to make rope for sailing vessels and lashings for wool bales. Much of it was exported to Australia. Maori had exploited this resource for generations by the time pakeha settlers established ropewalks along the Manawatu river banks in the 1840s.3 When the flax industry declined in the late 19th century the land was drained and converted to farming. First Makerua, and later Moutoa, the area with which we are concerned in this case.2 Measured at Palmerston North.3 T Buick Old Manawatu (Buick & Young, Palmerston North, 1903) 142; A J DreaverHorowhenua County & Its People (Dunmore Press, Palmerston North, 1984) 141-145.[9] The first flood protection works were constructed between 1923 and 1925. The Makerua Drainage Board constructed stopbanks to protect the Makerua basin. In the 1930s and 1940s more stopbanks were built, by the Manawatu-Oroua River Board and the Palmerston North River Board.Lower Manawatu Flood Control Scheme[10] The Lower Manawatu Flood Control Scheme (LMS) was undertaken by the Manawatu Catchment Board between 1959 and 1965. The LMS protects 320 square kilometres of land from flooding. But for these flood protection works, the city of Palmerston North, the town of Fielding, and significant areas of the region, in particular the Taonui, Makerua and Moutoa basins, would be prone to flooding in severe weather events.[11] The LMS relies primarily on stopbanks to contain floodwaters. A key part of the scheme, as we shall see, is the Moutoa floodway. The LMS is designed tocontain a "1 in 100 year flood", meaning that such a flood is expected (measuredover a very long period of time) to recur on average once every 100 years. To put it another way, there is a 1 per cent statistical probability of that flood size being equalled or exceeded in any given year. The LMS stopbanks were built with a design objective of a freeboard of 450 millimetres. That is, at all points the stopbank crests were to be 450 millimetres higher than the calculated 1 in 100 year flood level.[12] At the time of the February 2004 flood, the 1 in 100 year flood flow was set at 3,450 cumecs (measured at Palmerston North). At 3,500 cumecs, the February 2004 flow exceeded that level slightly. It is common ground that it was a "1 in 110 year" flood.Moutoa floodway[13] Downstream of the settlement of Opiki, and the confluence of the Manawatu and Oroua Rivers, there is a long oxbow bend where the Manawatu doubles back on itself. On the apex of that bend vast sluice gates have been built. These are the Moutoa sluice gates. The sluice gates were built in the early 1960s. They areregarded as a major engineering feat. When open, they allow the river flow to be split. The major part of the water is sent down the Moutoa floodway. The existing river channel will take the rest. The sluice gates serve as a critical safety valve. The change in gradient at Opiki means the river flow is far slower here than higher up the river. But for the ability to open the sluice gates, and divert part of the river down the floodway, floodwaters would bank up and overwhelm the stopbanks.[14] The floodway passes directly across low-lying farmland in the Moutoa basin. It runs from the oxbow bend to a point near the Manawatu river mouth. It is 10 kilometres long, and bypasses 30 kilometres of winding river channel. The floodway averages 600 metres in width. Its presence means that in all but floods exceeding the 1 in 100 year level, the Manawatu River water can be contained wholly within the existing river structure and the Moutoa floodway. The part of the Moutoa basin lying between the floodway and river channel should remain free from flood. It is that land the plaintiffs farm.[15] The flood levels in February 2004, a 1 in 110 year flood, were always goingto challenge the floodway and river's capacity to cope.Trestle bridge[16] Running at right angles to the floodway is State Highway 1. Just south of Foxton it crosses the floodway using a trestle bridge. The trestle bridge was built in the 1930s. The floodway, in the 1960s. The trestle bridge is lower than the adjacent floodway stopbanks. So, in effect, it cuts through them. Either side of the bridge, the stopbank crest runs up against the outer fascia of the bridge, at about road level. Beneath the bridge long beams run with the road, supporting the bridge deck. They project down from the bridge deck. The stopbank builders built the crest as far up beneath the bridge as they could. Then they filled in the spaces above the stopbank and between the beams with bags filled with cement and gravel. These harden to concrete. It is as if the spaces are filled with large flat rocks.[17] Applying and enlarging the advertising adage that a picture is worth a thousand words, I reproduce three images adduced in evidence, which depict the situation:Fig 1: bridge substructure, downstream of bridge, looking north towards Foxton.[18] Figure 1 shows that the side of the bridge comprises (1) a fascia (with safety parapet above) and (2) a series of longitudinal beams beneath (and inset from) the fascia. The beams project 480 millimetres below the fascia. This is the appropriate point to repeat some statistics that emerged in evidence:(a) The designed stopbank level at its conjunction with the trestle bridge was 5.2 metres above mean sea level. That is also approximately the road level of the bridge. Although settlement had occurred on the crest of the stopbanks adjacent to the trestle bridge, those deficiencies had been identified in May 2002. Repair work was conducted in June 2003. I find at the time of the February 2004 flood, the stopbank heights were likely to be at the 5.2 metres design level on either side of the trestle bridge.(b) The underside of the bridge (i.e. lowest point, the bottom of the downward projecting beams) is 4.52 metres above mean sea level. Thus, obviously, the bridge cuts through the stopbank.(c) A 1 in 100 year flood (i.e. flood levels for which the floodway was designed) would reach 4.63 metres above mean sea level at the bridge. At that level the flood waters would reach and lap the beams below the bridge fascia. But the floodwaters would still be contained within the stopbanks.(d) The peak level of the February 2004 flood at the bridge was slightly higher than the design level. It reached 4.65m above mean sea level. This level was reached at or shortly after 8.00 pm Monday 16 February 2004. That still left 550 millimetres freeboard between the flood level and the 5.2 metre stopbank crest - more than the design level of 450 millimetres freeboard.Fig 2: cement bag infill under bridge at northern stopbank abutment.[19] Figure 2 is a recent photograph of the northern end of the trestle bridge, at the point it abuts the stopbank. That is the bank opposite the one that failed. It shows how cement bags have been used to fill the gaps between the stopbank and the arches formed by the longitudinal beams. While representational, it is not an accurate picture of the position at the southern end of the trestle bridge in 2004. The northern end has a crossbeam4 at or about the crest of the stopbank at that point. At the southern end, however, the bridge straddled the stopbank. The piers were set part way up the slopes either side of the bank. No piers and crossbeam met on the stopbank crest there. The cement bags had to be built right up to the very underside4 That is the structure joining the piers to the bridge (forming the three low archways shown in Fig2).of the deck of the bridge. This is made clearer in the next figure, which is a cross- section drawing provided by one of the expert witnesses called by the Council.Fig 3: diagram produced by Mr N S Luxford, geotechnical engineer.Fig 3: cross-section diagram prepared by Mr Noel Luxford depicting probable southern stopbank/trestle bridge conjunction in 2002[20] The upper part of figure 3 is shown on a north/south plane (i.e. as if one was standing below the bridge, looking towards the stopbank). The lower part of the diagram is viewed on an east/west plane (as if one was standing on the stopbank, looking towards the bridge). Although the upper part of the diagram shows some settlement of the stopbank adjacent to the bridge, Mr Luxford drew his diagram as if set in 2002. As I have already said, I am satisfied that the stopbank was rebuilt to its design level either side of the bridge in 2003.LMS funding[21] The floodway stopbanks lie on land owned by the Manawatu-Wanganui Regional Council. LMS operating costs and capital improvements are funded by a special rating scheme. Eighty per cent is funded through targeted rating systems, paid for by those who benefit directly from flood protection. The remaining 20 percent is funded from the Council's general rate. Beneficiaries are represented on aScheme Liaison Committee. The Council is required to consult with the LiaisonCommittee before including the Scheme budget in the Council's draft annual plan.[22] The LMS budget for 2003/04 made provision for maintenance ($984,238), capital works ($70,773), flood damage reinstatement ($2,299,353) and"management/supervision/inspection" ($845,107). That cost was then spread, on adifferential basis, across 77,000 individual ratepayer beneficiaries.LMS review[23] In 1992 the Council commenced a comprehensive review of the LMS. Stage 1, which began that year, concerned the Palmerston North region where the potential flood damage was greatest. Stage 2 related to the rural reaches of the river, from Ashhurst (above the city) down to the river mouth near the Moutoa basin. A key part of the stage 2 review was a geotechnical investigation by Riley Consultants Ltd.The Riley report[24] The Council's brief required Riley to assess stopbank conditions and to identify high and medium priority sections requiring more detailed investigation. Higher priority stopbanks were to have permeability checks by digging test pits or drilling. Medium priority stopbanks would also be tested where preliminaryinvestigation indicated necessity. The brief also required the consultant "to checkthat services under, through or adjacent to the stopbanks do not compromise theirsecurity". In particular, it was to:...check for any signs of deterioration or damage to the adjacent stopbank or structure itself which may impair the security of the stopbanks.[25] Riley's report on the risk of failure of stopbanks, including those with whichwe are concerned, was presented in July 1994. The Riley report is essentially a geotechnical one. A preliminary examination of the stopbanks was followed by more intensive investigation. Twenty-eight test pits, 40 hand auger bore holes, 20 penetrometer measurements and a further 10 machine bore holes, were drilled. From these investigations Riley was able to express a view on constituent materials in the stopbanks and their engineering properties. Its assessment of the probability offailure, in the event of a "bankfull" flood was "low to moderate" for the relevantsouthern floodway stopbank, immediately above the bridge. Below the bridge therisk was "low". By contrast, Riley expressed concern about the state of the stopbank on the northern side of the floodway. This incorporated sandhill material. The riskabove the bridge was denoted as "very high." That below, "moderate". Rileyconcluded:The assessed risk of failure for a flood stopbank crest (i.e. at the point of over topping) is generally low. Some areas of high risk occur. These are generally applications under threat from undermining in the Manawatu/Oroua Rivers, and sections of the Moutoa floodway right bank which are at risk from piping failure in the foundations. These sections of the Moutoa floodway coincide with sandhills.[26] "Piping" happens when permeable materials in a stopbank permit water toflow through, and then course through, the stopbank. The consequence is that the stopbank will erode at the exit point.[27] Riley did not identify a particular risk associated with the trestle bridge, the focal point of this case.Stage 2 of the LMS review[28] Following the Riley report the Council's senior design engineer, Mr GrahamDoull, undertook an investigation of the LMS stopbank heights. He used a Danish computer modelling technique. By these means he located 5.5 kilometres of LMS banks lower than the 1 in 100 year design flood height. A further 20.7 kilometres had less than the required 450 millimetres of freeboard.[29] Mr Doull's work established that the floodway stopbanks were below the required freeboard level at two points. First, near the Stratton property, some 4.6 kilometres from the river mouth. Secondly, at the trestle bridge, some 1,200 metresfrom the river mouth. The Council's Group Manager of Operations, Mr Allan Cook,gave evidence that minor earthworks were undertaken in June 2003 to reinstate the design crest level of the floodway. The Council's records indicate a repair cost of$1,411. Mr Cook could not say precisely where that money had been spent. It appears likely however that the deficiencies at the bridge were fixed. He also noted that a more substantial freeboard reinstatement had also been undertaken approximately 3 kilometres upstream of the bridge, at a cost of $12,700. It isreasonably clear that this work reinstated the stopbanks near the Stratton property. It was there that the greatest deficiency in freeboard existed.[30] Ultimately the plaintiffs make no complaint about the height of the stopbanks, save immediately under the trestle bridge.[31] In 1998 Mr Doull prepared a stage 2 LMS review for consideration by Council. Based on the Riley report, Mr Doull prepared a list of works that could be done to further improve flood protection. Broadly the categories of work were the raising of stopbank heights to design height, prevention of undermining by rock armouring, prevention of piping failures where porous layers in the stopbank soils had been identified, and some stabilisation of structures. Mr Doull undertook a cost/benefit analysis and presented five upgrade options. Option 1 involved all works on the list being undertaken, but at a cost of $28 million. The least costly option was Option 5, in which only a few of the very high priority works were to be undertaken.[32] There was no evidence before me that any of the options, including the most expensive Option 1, involved works specifically at the trestle bridge.Public consultation[33] In 1999 the Council consulted with ratepayers about the options. The Easton family interests5 made a submission in favour of Option 4. That involved expenditure of $6.1 million. It does not appear that the second plaintiff made a submission.[34] A hearing committee convened to consider submissions. Eventually it recommended Option 4 be adopted. But with two additional items. The total capital cost was to be $6.6 million. Annual maintenance was also to be increased, from $1.1 million to $1.5 million. The option would result in a 50 per cent increase inbeneficiaries' rates. The works were to be carried out over a six year period, starting in 2000.5 The first plaintiff company was not yet conducting the family farming business.[35] The major thrust of Option 4 was to bring the stopbank crest height in all cases to 450 millimetres above the design flood level. That accounted for 65 per cent of the expenditure. Option 4 included the reinstatement work near the trestle bridge and the Stratton property that I have already described.6The February 2004 floodThe flood generally[36] As noted earlier7 the February 2004 flood was the third largest on the Manawatu River since recording began in the 19th century. It was the largest flood since 1902. The tributary Oroua River experienced its largest ever recorded flood. The floodwater was greatly in excess of the design levels of its stopbanks. The Oroua stopbanks failed in five places. The resulting flooding was said to be"extensive and destructive". Failures also occurred on the Manawatu Riverstopbanks at Koputaroa, on Kauri Creek, and on the Moutoa floodway at the trestle bridge. It is that failure that directly concerns us in this case.[37] Heavy rain had occurred in the catchment in late January, and in early February 2004. The catchment was already very wet prior to the 15-16 Februarystorm. Heavy rain fell on 14, 15 and 16 February. At Moutoa, the Council's raingauge recorded 62.6 millimetres across those three days. The total for the month was 250 millimetres - compared to a monthly mean of 67 millimetres. By way of comparison, 45 millimetres fell in January and 22 millimetres in March. Throughout the rest of the year the highest rainfall month was June, with 131 millimetres. The February rainfall event was, therefore, exceptional.[38] Measured at Palmerston North, the Manawatu River was running at a maximum flow rate of 3,500 cumecs. As at 2004, the river system provided for a 1 in 100 year flood at 3450 cumecs flow. On that basis, therefore, the February 2004 flood was, by a small margin, an over-design flood. The consequence was that the6 At [29].7 At [6].February 2004 flood rose into the 450 millimetre design freeboard level in some places.[39] Council officers, including Mr Doull, used a sophisticated computer modelling system to identify likely river flows during the period of heavy weather. By midnight on Sunday 15 February, it was appreciated that the Moutoa sluice gates would need to be opened, to divert river flow down the Moutoa floodway. Landowners were advised, so they could move stock. The gates were opened at 7.00 am on Monday 16 February. Soon after, it became apparent that the Oroua River was in a state of exceptional flood. As Mr Doull put it:During the morning of 16 February it was abundantly clear that the Manawatu River would be carrying a flood that at least approached its design flood, and would possibly exceed it.[40] The peak flow past Palmerston North occurred at about 6.30 pm on Monday 16 February, although the river remained within 100 millimetres of its peak between midday and 9.00 pm that day. The peak flood downstream at the Moutoa trestle bridge occurred somewhat later of course, at or after 8.00 pm.[41] As noted at [18], the peak floodwaters reached 4.65m at the bridge. But the bridge itself offered only 4.52m clearance. So the bridge structure intruded into, and constricted, the flood flow.Moutoa basin flooding[42] Before anyone appreciated that there had been a failure in the Moutoa floodway stopbank, local farmers and others were reporting to Council that ponding was occurring near the trestle bridge. That is, in the Moutoa basin, to the south of the floodway.[43] I now turn to the eye-witness accounts of the stopbank failure. They are of considerable importance when eventually the issue of causation is considered.88 At [195-223].(1) Mr Jamieson[44] Mr Lee Jamieson lives in Levin. At about 5.00 pm on the evening of Monday 16 February 2004, he went with his family to watch the flood on the Moutoa floodway. They stood on the top of the southern stopbank, downstream of the trestle bridge, near the cycleway. About 10 metres downstream of the bridge. This part of the stopbank, where Mr Jamieson and his family were watching the flood, collapsed spectacularly the following morning.9 Mr Jamieson said:I could see and hear water flowing over the top of the stopbank under the bridge. I am positive it was flowing under the bridge and not on either side. It was approximately half a metre to one metre wide and 20 centimetres deep.Under cross-examination by Mr David Heaney SC for the Council, however, Mr Jamieson confirmed that at that stage the flow was really more in the nature of a"slow trickle" beneath the bridge and above the cement bags. At that stage he couldsee no ponding of water in the Moutoa basin, to the south of the stopbank. That was, of course, three hours before the peak of the flood.(2) Mr Stratton[45] Mr Darryl Stratton farms in the Moutoa basin. His farm is south of the southern stopbank. It lies between State Highway 1 and the plaintiffs' farms. At1.45 am on the morning of Tuesday 17 February, Mr Stratton decided to check his paddocks. He drove west along the Whirokino Road towards the highway. The road skirts the edge of the Manawatu River. The point where the road passes beneath the trestle bridge is about 500 metres south of the stopbank.[46] As Mr Stratton attempted to drive under the trestle bridge, he came upon ponded water. He assessed it to be about 1.5 metres deep. He decided not to venture further. He told me that he had lived in the area all his life. He had never seen water ponding to that extent. He believed for the road to have filled up like that, water had to have come down from the floodway. Certainly no one suggested to me that the9 See [61].water could have come from the river. Its stopbanks to the south of the Moutoa basin held fast throughout the flood.[47] Mr Stratton went home and rang the Council. The Council officer asked him to check again. So at about 2.00 am Mr Stratton went back to the scene. This time he did not try to drive under the trestle bridge. Instead he drove up an access road onto the bridge, over the highway and back down onto Whirokino Road west of the bridge. He then went for a walk along the southern stopbank back towards the trestle bridge. He began to feel extremely uneasy. He could see water on both sidesof the stopbank. The floodway water was "roaring". He rang the Council on his cellphone and reported the situation. He said he could not see any stopbank breach, but he was well west of the bridge when he made the phone call. He then went home again. But not for long.[48] At about 3.00 am Mr Stratton and his partner looked out their bedroom window. They could see sheets of water across their farm. The water was being held back by a metre high cow race between the stopbank and the house. As theywatched, the water crossed the race "like a wave". Mr Stratton and his familyevacuated the property. In about two minutes the water was knee deep inside their house.(3) Mr Doug Easton[49] Mr Doug Easton is a dairy farmer. He is related to Mr Ian Easton, the drivingforce behind the first plaintiff. Mr Doug Easton's main farm is near Waitarere, northof Levin. But he also has two smaller blocks in the Moutoa basin area, and he leases 500 acres within the floodway itself. As the weather worsened on Monday 16 February he moved his stock out of the floodway, to higher ground on one of his Moutoa basin blocks. At 3.20 am on the Tuesday morning he received a call from arelative reporting that water was lapping around Mr Stratton's house. As he still had700 cows in the basin, he headed there straight away.[50] Standing on the trestle bridge at the point it meets the southern stopbank, he looked upstream. He saw what appeared to be a breach in the bank upstream of thebridge, with "water pouring through". Concerned for his safety, he headed off thebridge. Returning to his block west of the highway he found water in his paddocks, perhaps a metre deep. The cattle in the paddocks were in distress. Mr Easton was able to open some gates. The stock headed off to higher ground, the Manawatu River stopbank to the south.[51] Then, between 5.30 and 6.00 am the same morning, Mr Easton was standing on the river stopbank, along with his stock. He looked back at the floodway stopbank:I could see quite clearly water pouring through the bank on the eastern [i.e. upstream] side of the bridge. I could not see under the bridge because of the water that was flowing through the bank on the eastern side. I could see bits of the stopbank upstream of the bridge breaking off as the water scoured it away.(4) Mr Richard Barber[52] Mr Richard Barber farms to the north of the Moutoa floodway. He drove down to the bridge, arriving at the north end at 5.30 am. This was about the sametime as Mr Doug Easton's observations, but of course from the opposite end of thebridge.[53] Mr Barber got out of his vehicle to talk to a roading worker. As they watched, he could see water flowing out of the floodway upstream of the bridge, into the basin. He also saw it flowing over the stopbank on the downstream side. Unfortunately Mr Barber was a very early witness, and neither counsel nor the Court asked him to locate precisely where he saw this water flowing, relative to the bridge. That issue was to prove important later in the trial.[54] Mr Barber left the flood scene at that point. He went to fetch his father.(5) Mr Stuart Barber[55] Mr Stuart Barber10 and his son Richard arrived at the bridge at about 6.15 am. They were in the left lane, coming from the north, so Mr Barber Snr's attention wasfirst drawn upstream of the bridge. He said:I could see clearly brown water flowing across through the bank on the eastern [i.e. upstream] side of the trestle bridge.He said he thought the bank immediately upstream of the bridge had "disappeared".They then parked and crossed the road. Just as his son had, Mr Barber also saw water flowing through the stopbank on the downstream side of the bridge. Mr Barber's evidence ultimately was unclear whether this initial downstream breach was immediately adjacent to the bridge or not.(6) Mr Owen Bonis[56] Mr Bonis is the Levin branch manager for Higgins Contractors Limited. He was responsible for closing the trestle bridge during the night. There had been concern about the safety of the bridge. Mr Bonis noted:The ... water was right up close to the underside of the bridge and debris which normally occurs with floods was starting to be caught in the structure of the bridge.[57] At about 5.30 am on the Tuesday morning Mr Bonis stationed himself at the south end of the bridge, near the Manawatu River stopbank. From that location he could see the floodway stopbanks about 500 metres north. His perspective would have been similar to that of Mr Doug Easton, although a little more to the west. A colleague from Higgins was posted at the north end of the Moutoa floodway. It was that colleague presumably who spoke to Mr Richard Barber.[58] From his position on the highway, Mr Bonis could not see under the bridge. But he could see a breach in the stopbank downstream of the bridge. In his evidence10 Mr Barber's background is discussed at [162].he said he thought he could still see intact stopbank between the bridge and the downstream breach. Mr Bonis seemed to have no recollection of the upstream breach seen by Messrs Doug Easton, Richard Barber and Stuart Barber.(7) Mr Graeme Anderson[59] Mr Anderson was a works supervisor for the Council at the time of the flood. He was in charge of the Shannon work gang. He was responsible for inspecting the Moutoa floodway stopbanks. I will comment later on his evidence in relation to that responsibility.11 But on the Tuesday morning he detoured to the bridge, to look at the flood, while driving his wife to work. Mrs Anderson started work in Foxton at 6.00 am, so they were at the north end of the bridge a little after 5.30. At that stage Mr Anderson saw a shallow breach in the stopbank very near the cycleway, about 10 metres downstream of the bridge. He is sure that the 7-8 metres of the stopbank immediately downstream of the bridge was still intact. He had his binoculars with him. He used them to survey the stopbank, in which of course he had a particular interest. He does not seem to have paid particular attention to the upstream side, however. That was all he saw at that stage.[60] He dispatched Mrs Anderson to work and returned at about 6.00 am. He remained at the site for the next 40 minutes or so. He saw the breach downstream of the bridge enlarge until a catastrophic failure occurred.Catastrophic stopbank failure[61] It is common ground that at approximately 6.30 am on the morning of Tuesday 17 February 2004 the southern stopbank, between the Moutoa floodway and the Moutoa basin, gave way downstream of the bridge. The collapse was described by several of the foregoing eye-witnesses as "spectacular". The stopbank "blewout". Water rushed from the floodway into the Moutoa basin, and proceeded to back up the basin towards the plaintiffs' farms.11 At [165].[62] The breach, ultimately, reached 23 metres upstream from the centreline of the bridge, and 17 metres downstream. The bridge survived, intact.Sutherland report[63] Following the February 2004 flood and the various failures in the Council'sflood protection systems, the Council commissioned a review. The convenor was Dr A J Sutherland, Dean of Engineering at the University of Canterbury. There were three other engineering members of the team. One of them was Mr P B Riley. His firm had undertaken the 1994 geotechnical review.12 The review report is known as the Sutherland report. It was delivered in April 2004. It is a mixture of expert analysis and reportage. It refers liberally to information obtained from eye- witnesses. Some of those eye-witnesses gave evidence in this case, but not all. The Sutherland Committee was asked to consider the possible causes of failures, and to recommend appropriate forms of repair to avoid recurrence.[64] On the reportage front, the Committee report contains some information that was not in evidence before me, and which I must put aside. For instance, an unnamed witness who reported a 300 millimetre water level drop at 6.00 am, before the major downstream breach of the stopbank. Similarly, two eye-witnesses whoheard a "large bang" at 1.30 am the same morning. I shall disregard all that.[65] As to the failure of the stopbank at the trestle bridge, the Committeeconcluded that the likely cause of failure was "the interaction between the bridge structure and the stopbank". The Committee noted that the upstream water levelstriking the soffit caused a "pulsing" in the flow and increased velocities under thebridge and along the stopbank face. Any debris caught on the bridge would have exacerbated the situation. The Committee felt the presence of the bridge piers may have contributed to local scouring. But the experts who gave evidence before me all agreed that if local scouring had been a significant concern, earlier floods should have identified that.12 See at [25].[66] The Sutherland Committee considered a possible explanation of the reported flooding in the Moutoa Basin early Tuesday morning was a failure "at the vertical interface between the bridge structure and the stopbank". The pulsing nature of the flow, in conjunction with "observed strong wave action" could have exploited aweakness at the interface, and could have caused sufficient scouring to lower the bank and cause the considerable overflow observed at 3.00 am. The Committee discounted seepage as a cause of failure, in the absence of direct evidence to support it. The Committee recommended improved armouring of the bank/bridge interface, and more effective sealing of the area under the bridge via a flexible waterproof butynol liner.PartiesPlaintiffs[67] The first plaintiff, Easton Agriculture Limited, is a family-owned company. One of its directors, Mr Ian Easton, gave evidence. He has farmed in the area all his working life. The farm relevant to this case is located in the Moutoa basin on the Foxton Shannon Road. It is about 250 hectares in area. It was formerly farmed by Mr Easton's parents. The family has been there since 1961. The Eastons growmainly potatoes, onions, squash, grass seed and cauliflower. They also run dry stock: cattle and some sheep.[68] Mr Easton is a highly regarded farmer. In 2005 he won the Hill Laboratories Harvest Award. He is committed to sustainable farming, and operates a policy of strict crop rotation. He plants crops for two years, and then grasses the paddock for the next five.[69] The second plaintiff's farm, known as Bussitons, is tucked against Mr Easton's at its north eastern boundary. It is a somewhat smaller operation, about 67 hectares, and I heard less about it in evidence. Mr Eveleigh has been farming in the Opiki area for approximately 50 years. He devoted himself to two crops: onions and potatoes.[70] Both the Easton and Eveleigh farms are in an excellent area for potato production. The area is largely frost-free. The summer is moist because of the Ruahine ranges just to the east. The two farms are situated on Kairanga silt loam. That is some of the best soil there is for potato production, because potatoes can be stored in the ground until needed. The crop can mature, but need not be harvested immediately.[71] The breached stopbank flooded the Moutoa basin. A vast amount of water flowed back up the basin from west to east. The area covered by water has been estimated at 2000 hectares. The water volume is not known. Floodwaters ran up open drains cut into the basin by drainage boards and farmers in earlier years. That exacerbated the flooding. Almost all Mr Eveleigh's farm was flooded. So was a large part of Mr Easton's. Mr Easton had lifted a crop of onions for harvest prior to the flood. They floated on the floodwaters and ended up piled a metre high against a fence line. The floodwaters covered the plaintiffs' farms for up to 12 days.[72] Although there was argument over the extent and duration of flooding (which would need to be resolved as part of any quantum hearing), it is undenied that the flood caused substantial damage to the plaintiffs' properties and crops.Defendant[73] The defendant is the Manawatu-Wanganui Regional Council. For reasons notgiven in evidence, it prefers to call itself the "Horizons Regional Council". Iimagine that reflects the fact that the region is rather flat.[74] The Council is responsible for 33 river and drainage schemes. Each scheme is a separate entity, funded largely by targeted differential rating systems.13 The LMS is the largest of the 33 schemes. It accounts for 45 per cent of total scheme expenditure.[75] These schemes were previously managed by the Manawatu Catchment Board and the Rangitikei/Wanganui Catchment Board. But in 1989 there was a13 At [21].reorganisation of local government in the area. The Local Government (Manawatu- Wanganui Region) Reorganisation Order 1989 dissolved the catchment boards. Their functions, duties and powers under the Soil Conservation and Rivers Control Act 1941 were transferred to the Council.PleadingsClaim[76] The plaintiffs claim that following the opening of the Moutoa sluice gates, and the filling of the floodway on 16 February 2004, "the stopbank on the true lefthand side14 of the floodway progressively failed and breached in the vicinity of the trestle bridge, [and] the flood waters escaped the floodway and flowed backupstream". The Council admits that allegation.[77] The plaintiffs then allege the stopbank failure occurred because of theinadequate condition of the stopbank under the trestle bridge ("in particular the interface between the stopbank and the bridge"), the floodway landform geometry, the alleged poor condition of the cement bag infill under and in the vicinity of the bridge, the flood waters lapping onto the bridge beams, and the consequent hydraulic effects resulting from those various conditions. The Council denies all those allegations.[78] The plaintiffs advance their case on four bases: negligence, private nuisance,Rylands v Fletcher liability, and breach of statutory duty. I will traverse each, briefly.[79] Negligence: the plaintiffs allege that the defendant was negligent in failing to"note or in any way evaluate the conditions of the stopbank under the bridge" whenit reviewed the LMS in 1997 and 1998; failing to model the bridge when assessingthe hydraulic capacity of the floodway; and "failing to generally maintain to designstandard and/or monitor the condition of the stopbank under the bridge".14 The "true left" and "true right" banks of a river or other waterway are defined by lookingdownstream.[80] The plaintiffs' opening confirmed the focus of their case on the areaimmediately beneath the bridge. In particular, on the existence of an alleged gap above the cement bags, and beneath the underside of the bridge deck. Mr John Upton QC for the plaintiffs submitted:In summary, the stopbank had narrowed under the bridge and the cement bags on top of the bank under the bridge had apparently settled leaving a significant gap. The stopbank at the bridge was in an inadequate condition, so that when the flood level came to the bottom of the bridge beams, water would simply have washed out and overflowed under the bridge.But the narrowing of the stopbank was not ultimately considered by any of theexperts (including the plaintiffs' expert) as causative.15 I discount it accordingly.[81] Furthermore, in closing Mr Upton made it abundantly clear that the plaintiffs were staking their claim firmly on deficiencies in the Council's "maintenance and monitoring" of the stopbank. Mr Upton expressly disavowed any assertion that thestopbank construction was actionable.[82] The plaintiffs' claim in negligence was not confined to breach of the bank. Italso extended to the Council's response to the emergency, both in its immediateresponse to the risk of flooding while the progressive failure was occurring, and in preventing certain remedial work being undertaken by the plaintiffs in an attempt to block the flow of water up the Moutoa basin.[83] Nuisance: the plaintiffs plead that the facts give rise to an action of private nuisance, causing loss. That is about the substance of that pleading.[84] Rylands v Fletcher liability: the plaintiffs also plead that escape of water from land under control of the Council, resulting in damage, creates liability on aRylands v Fletcher basis.[85] Breach of statutory duty: finally, the plaintiffs plead breach of statutory duty. The relevant duty is that under s 126 of the Soil Conservation and Rivers Control Act 1941:15 See [209].It shall be a function of the River Catchment Board to minimise and prevent damage within its district by floods and erosion.[86] The first plaintiff claims damages of $1,412,467. The second plaintiff, $1,127,920. The damages claims are confined to loss of income from sale of flood- damaged crops. No damage for harm to other property, or for reduced production in later years, are claimed. Interest and costs are sought.Defence[87] The Council denies each of the claims. It advances a number of defences. One, based on the Land Drainage Act 1908, was abandoned in closing. Those remaining were four in number.[88] Statutory defence to all claims other than negligence: the Council contends that rights of action other than negligence are not available to the plaintiffs, because of s 148 of the Soil Conservation and Rivers Control Act 1941. I will return to this topic shortly.16[89] Rylands v Fletcher: natural user: the Council pleads that the use of the Moutoa floodgates and floodway for the purpose of draining the district was an ordinary, natural use of the land. On that basis it would fall within an exception to the rule in Rylands v Fletcher.[90] Rylands v Fletcher: act of God: if the foregoing defences do not prevail, the Council pleads that the storm event was of such magnitude as to constitute an act of God, for which it is not liable.[91] Limitation Act 1950: finally, the Council pleads that the plaintiffs'allegations are time-barred by s 4 of the Limitation Act 1950, to the extent they relate to any act or omission by the defendant occurring prior to 24 January 2002. That is six years before the original statement of claim was filed.[92] I turn now to the issues arising in this case.16 At [94].Issues[93] The issues arising in this case are four in number:(a) Can the Council be liable other than in negligence?(b) Did the Council owe the plaintiffs a duty of care in its monitoring and maintenance of the stopbank?(c) Was the Council negligent?(d) Did the Council's negligence cause the plaintiffs' loss?Issue 1: Can the Council be liable other than in negligence?[94] It is best to address this issue first.[95] Section 148(1) of the Soil Conservation and Rivers Control Act 1941 provides:No Board shall be liable for injury to any land or other property caused without negligence of the Board by the accidental overflowing of any watercourse, or by the sudden breaking of any bank, dam, sluice, or reservoir made or maintained by the Board.Submissions[96] I start with the Council. It submits, in short, that claims against it arising from breach of the stopbank can be maintained (if at all) only in negligence. It says that the other three claims – private nuisance, Rylands v Fletcher and breach of statutory duty – are subsumed by statute into a single potentially permissible claim of negligence. But, as we shall see17 the Council also denies that a duty of care can arise at all in this case.17 At [132].[97] Ms Sarah Macky argued this part of the case for the Council. She submitted that s 148 reflects a policy judgment made by Parliament to preclude liability of a strict nature for catchment boards (and therefore for regional councils assuming their functions under the Act) in major rainfall events. That is because those bodies simply have no control over such events. She submitted that to hold catchment boards strictly liable for losses arising out of massive natural events would be unduly harsh, and would fly in the face of the express words of the statute. The provision thus prevents a finding of liability under common law actions for nuisance, Rylands v Fletcher and breach of statutory duty in this case.[98] Ms Macky was unable to refer me to New Zealand authority directly on point. In Burke v Waikato Regional Council18 a District Court affirmed the right of a property owner to bring an action in negligence for inundation resulting from the alleged failure of a floodgate structure maintained by the regional council in that case. That case involved a striking-out application, and does not take things much further. The same could be said for a High Court decision Atlas Properties Ltd v Kapiti Coast District Council.19 That was a claim arising from a storm which had caused under-road culverts to overflow. The council sought to rely on s 148. Durie J held that the section was not available to it as a defence. It was not a catchment board for the purposes of s 148. Moreover, the work undertaken by the council in relation to the culvert was not work contemplated as part of the functions of a catchment board. Those conclusions clearly were correct. The decision was upheld on appeal, albeit on different grounds.20[99] Turning now to the plaintiffs, Mr Upton submitted s 148 of the Act applies only to conduct carried out without neglect. In this case the plaintiffs claim that theCouncil's neglect or negligence was causative of their loss. Accordingly s 148 would not apply.[100] Secondly, Mr Upton submitted that the Local Government (Manawatu- Wanganui Region) Reorganisation Order 1989 provided only for the Council to take18 Burke v Waikato Regional Council [1996] DCR 897.19 Atlas Properties Ltd v Kapiti Coast District Council HC Wellington CP 172/00 19 December2001, per Durie J.20 CA30/02, 20 June 2002.over the "functions, duties and powers" of catchment boards under the SoilConservation and Rivers Control Act 1941. Said Mr Upton, "That order does not include the immunity or statutory protection available in s 148". The approach contended for by the plaintiffs, he submitted, provides a "better fit" with s 247H of the Local Government Act 1974 and s 191 of the Local Government Act 2002. These provide that a local authority is not entitled to create a nuisance, or deprive any person of any right or remedy that person would otherwise have in respect of a nuisance.Analysis[101] I reach three conclusions.[102] First, the Council is the "Board" for the purposes of s 148 of the Act. Thiswas admitted by the plaintiffs. They of course contend that the responsibilities imposed on such a Board in s 126 gives rise to an actionable statutory duty. So they cannot have it both ways, and do not try to.[103] It is worth setting out why the Council is the "Board". The LocalGovernment (Manawatu-Wanganui Region) Reorganisation Order 1989 gave effect to a reorganisation scheme advanced by the Local Government Commission. This dissolved a number of territorial authorities in the Manawatu and Wanganui regions. Three united councils, a city council, numerous borough district and county councils, two catchment boards and five drainage boards. All dissolved. The property of certain of these bodies (and in particular of the Manawatu Catchment Board and the Moutua Drainage Board) was vested in the new regional council. More importantly, the Order provides:21The functions, duties, and powers of the Manawatu-Wanganui Regional Council shall be:...(d) The functions, duties, and powers of a Catchment Board and a Regional Water board under the Soil Conservation and Rivers21 Cl 16(1)(d).Control Act 1941 and the Water and Soil Conservation Act 1967 or any other Act.[104] This was a commonplace reform in 1989. As far as I am aware, there are no catchment boards left in New Zealand. All have been subsumed into regional councils. Nonetheless, the Act remains in place and imposes certain duties on"catchment boards". Section 126 is one such provision. Another, s 145, provides forclaims against catchment boards for land damaged or injuriously affected.22 Section 148 follows shortly after that provision.[105] In my view the intention of Parliament was simply that s 148 apply to any body undertaking the lawful functions, powers, and duties of a catchment board, under the Act, in maintaining watercourses or banks.[106] Secondly, s 148 means what it says. The Council's liability for damage to property resulting from "the sudden breaking of any bank" (which is what happenedhere) is dependent on proof of negligence. In my view this has the statutory consequence of effectively displacing other forms of liability, apart from negligence. The provision operates not so much as a defence to the common law forms of action other than negligence, as an ouster of them. It follows that my conclusion in relation to s 148 disposes, also, of any claims in nuisance and breach of statutory duty.[107] Thirdly, even if I had not reached the conclusion that s 148 excluded liability under the rule in Rylands v Fletcher, I would have held that the rule does not apply in this case.[108] It is worth reminding ourselves that the rule in Rylands v Fletcher represented not so much an advance in the law in 1866, as a reversion to a more medieval approach to tort liability. One in which liability was absolute, regardless of negligence. By 1866 negligence had become the effective organising principle of actions on the case. Neglect – negligence – characterised actions on the case, in22 Soil Conversation & Rivers Control Act 1941, s 145.contrast to trespass which tended to focus upon intentional wrongdoings. Rylands v Fletcher, as the late Professor A W B Simpson23 points out, was an action broughtsquarely on the basis that Mr John Rylands' reservoir, built above old coal workings,24 was "carelessly and negligently constructed".25 At first instance anarbitrator had found Mr Rylands' contractors negligent. But not Mr Rylandspersonally. The former were not worth pursuing. The latter was not vicariously liable for their actions. Mr Fletcher therefore pursued Mr Rylands in his personal capacity to the Court of Exchequer in banc (where he lost) and thence (but now on the basis that liability should be strict) to the Court of Exchequer Chamber26 (where he won). There, Blackburn J said, famously:27We think that the true rule of law is, that the person, who for his own purposes brings on his land and collects and keeps there anything likely to do mischief if it escapes, must keep it at his peril, and that if he does not do so, he is prima facie answerable for all damage which is the natural consequence of its escape.[109] Thus a negligence case was transformed into a strict liability one. ProfessorSimpson's study offers a possible explanation for this jurisprudential diversion. In the decade before Rylands v Fletcher was decided, two other large reservoirs had failed, and far more catastrophically. First, in 1852, the Bilberry Dam:28Construction of this decrepit, ill-designed, and ill-maintained structure had begun in 1839, and its collapse at 1 a.m. on Thursday, February 5, 1852, came as no surprise; some fifty or more people were standing at or near the dam at the time, confidently expecting it to go. Others, more optimistic or fatalistic, had retired to bed below it.Seventy-eight died and there was widespread property loss. Then the Dale Dyke embankment, near Sheffield (and overseen by the nephew of the Bilberry Dam engineer) failed in 1863. The death toll this time was 238. The property owner23 Professor Brian Simpson was a pre-eminent historian of the common law. Lamentably he diedearlier this year, on 11 January 2011, precisely 150 years (and one month) after the actionableevent in Rylands v Fletcher.24 Through which, on 11 December 1860, the water burst downwards, emptying Mr Rylands'reservoir but inundating Mr Thomas Fletcher's coalmine.25 See A W B Simpson Legal Liability for Bursting Reservoirs: The Historical Context of Rylandsv Fletcher (1984) 13 J Leg Stud 209 at 212.26 Occupying the same essential function as that performed by the Court of Appeal, whenconstituted in 1875.27 (1866) LR 1 Exch 265, 279-280.28 Op cit n 25, at 219.claimants briefed Sir Hugh Cairns QC. It was he who, as Lord Cairns, affirmedBlackburn J's decision when Rylands v Fletcher reached the House of Lords. In the ensuing compensation proceedings,29 the dam owner was represented by counsel who acted for Mr Rylands. And the Dale Dyke claimants were represented by counsel who thereafter was for Mr Fletcher.[110] Since Rylands v Fletcher we have seen the rule applied to a number of community or privately conveyed utilities: water,30 sewerage,31 electricity,32 and gas.33 As Professor Smilie has pointed out,34 the cases in which liability for these activities has arisen have tended to be ones involving bulk conveyance, as opposed to domestic installations. But the dividing line is by no means distinct.[111] Due regard to the context and content of Rylands v Fletcher might suggest that this rule concerning the escape of dangerous things might itself be more confined. Its proper function is to impose, exceptionally, strict liability for escaping hazards that are of their nature (1) very dangerous and (2) (perhaps) unexpected, so that the adjacent land owner cannot make satisfactory alternative provision – e.g. by insurance.[112] In Australia the High Court of Australia abandoned the rule in Rylands v Fletcher in Burnie Port Authority v General Jones Pty Ltd.35 It held that it had been absorbed within general principles of negligence, public nuisance and trespass. In doing so it returned some way to the orthodox position ex ante Rylands v Fletcher. Although Burnie was a majority decision, the High Court of Australia has not revisited the issue.29 The dam owner was subject to a wide-ranging and strict compensation provision in the privateAct of Parliament authorising construction of the dam: s 68 of the Sheffield Waterworks Act1853. The provision had been inserted in the bill following the Bilberry Dam disaster:Simpson, op cit n 25, at 234-237.30 Charing Cross Electricity Supply Co v Hydraulic Power Co [1914] 3 KB 772 (CA); Irvine &Co Ltd v Dunedin City Corporation [1939] NZLR 741 (CA).31 Smeaton v Ilford Corporation [1954] Ch 450 (Ch D).32 Hillier v Air Ministry [1962] CLY 2084 (a case where cows were electrocuted by high voltagecables laid beneath the plaintiff's fields).33 North Western Utilities v London Guarantee & Accident Co [1936] AC 108 (HL); Hanson vWearmouth Coal Co [1939] 3 All ER 47 (CA).34 Smillie, "Non-natural Use" [2011] NZLJ 88.35 Burnie Port Authority v General Jones Pty Ltd (1994) 179 CLR 520 (HCA).[113] In England, the House of Lords was invited to take a similar approach inTransco plc v Stockport Metropolitan Borough Council.36 But it declined the invitation. In an earlier appeal, in Cambridge Water Co Ltd v Eastern Counties Leather plc, Lord Goff had said that, as a general rule, the imposition of strict liability is more appropriately a matter for Parliament than the Courts.37 The same might also be said of abolition of the rule. But confinement in accordance with original purpose is another thing. The House of Lords did exactly that in Transcowhen Lord Bingham said:38Bearing in mind the historical origin of the rule, and also that its effect is to impose liability in the absence of negligence for an isolated occurrence, I do not think the mischief or danger test should be at all easily satisfied. It must be shown that the defendant has done something which he recognised, or judged by the standards appropriate at the relevant place in time, he ought reasonably to have recognised, as giving rise to an exceptionally high risk of danger or mischief if there should be an escape, however unlikely an escape may have been thought to be.[114] In New Zealand, the Court of Appeal too has declined to follow the Australian abrogation option. In Autex Industries v Auckland City Council39 the defendant council was sued in respect of a burst water main. It submitted that New Zealand should follow Burnie and treat Rylands v Fletcher as having been subsumed into the law of negligence. A majority of the Court contemplated the possibility that the concept of non-natural user might be different now from when the similar fact pattern in Irvine & Co Ltd v Dunedin City Corporation40 was decided. The minority appeared to consider Irvine still good law, and remained critical of the approach taken in Burnie. They cited with approval this observation of Professor John Fleming, supporting Rylands v Fletcher as a vital component of tort theory:41Negligence deals with the wrong way of carrying out an activity, the residuary risk of which it is not unfair for victims to shoulder themselves. Strict liability deals with activities which even when carried out with due care, retain an abnormal risk and could be deemed negligent as such but for their countervailing utility.36 Transco plc v Stockport Metropolitan Borough Council [2004] 2 AC 1 (HL).37 Cambridge Water Co Ltd v Eastern Counties Leather plc [1994] 2 AC 264 (HL) at 305.38 Transco plc v Stockport Metropolitan Borough Council [2004] 2 AC 1 at 11.39 Autex Industries v Auckland City Council [2000] NZAR 324 (CA).40 See note 30 above.41 (1995) Tort Law Review 56 at 60.[115] Certainly, as the House of Lords held in Transco, there will be a residue of cases where strict liability properly applies. As noted earlier, such cases involve the imposition of exceptional hazard and (from the adjacent owner's perspective) unexpected outcome.42 Take, for instance, the lawful manufacture or storage of explosives. If through no fault of anyone at all they explode, and devastate the neighbourhood, are the neighbours to be denied compensation for want of proof of fault?[116] It may well be time, however, to reconsider whether the rule should apply to commonplace utilities, such as water and sewerage. Particularly where their presence is obvious to adjacent landowners. It may be that Courts will eventually conclude that liability for the failure of such systems is dependent in all cases on proof of negligence.[117] Regardless however of these philosophical considerations, two particular responses to the Rylands v Fletcher claim, additional to s 148, can be made in this case.[118] First, a floodway built through a flood-prone district is not a non-natural use of the land. The very necessity for its construction suggests that it is not. The consequence of not having constructed the floodway would, in the context of this storm event, likely have been inundation of the Moutoa basin and surrounding district. The works do not of their nature engage hazard; rather they seek to defray hazard that natural causes have already created. In a context where works are constructed to remove (or at least diminish) a risk otherwise present, it seems counter-intuitive to regard them as creating an exceptional hazard. And, moreover, their presence is immediately apparent to adjacent landowners. Those landowners knew they were a community work, and that they were not completely flood-proof in nature. The community set the extent to which capital should be spent on the stopbanks. It can be taken to have had an informed appreciation of the general risks associated with them.42 If the hazard is simply stored, for instance, the adjacent owner may not be aware of the activity'sexistence at all.[119] Such a view is supported by the decision of La Forest J (with whom Dickson CJ agreed) in Tock v St John's Metropolitan Water Board.43 In that case there had been a ferocious rainstorm. A nearby stormwater drain failed to work, and theplaintiff's basement was flooded. La Forest J concluded that the installation ofpublic drainage systems was "an indispensable part of the infrastructure necessary to support urban life" and could not be characterised a non-natural use.44[120] The second response is that the very statutory duty relied upon by the plaintiffs to found their breach of statutory duty claim creates a fundamental objection to Rylands v Fletcher liability. Section 126 of the Soil Conservation andRivers Control Act 1941 provides that "it shall be a function of every catchmentboard to minimise and prevent damage within its district by floods and erosion". AsLord Scott put it in Transco:45... it is, I think, worth reflecting on why it is that an activity authorised, or required, by statute to be carried on will not, in the absence of negligence, expose the actor to strict liability in nuisance or under the rule in Rylands v Fletcher. The reason, in my opinion, is that members of the public are expected to put up with any adverse side-effects of such an activity provided always that it is carried on with due care. The use of the land for carrying on the activity cannot be characterised as unreasonable if it has been authorised or required by statute. Viewed against the fact of the statutory authority, the user is a natural and ordinary use of the land. This approach applies in my opinion, to the present case. The council had no alternative, given its statutory obligations to the occupiers of the flats, but to lay on a water supply. Strict liability cannot be attached to it for having done so.Conclusion[121] For the reasons given above, which centre upon s 148 of the SoilConservation and Rivers Control Act 1941, the Council's liability to the plaintiffs inthis case is dependent on proof of negligence.43 Tock v St John's Metropolitan Water Board [1989] 2 SCR 1181 (SCC).44 At [74]. The remaining members of the Supreme Court determined the case on other grounds.45 Transco plc v Stockport Metropolitan Borough Council [2004] 2 AC 1 at 33.Issue 2: Did the Council owe the plaintiffs a duty of care in its monitoring and maintenance of the stopbank?Duty of care[122] The essential case for the plaintiffs is that the Council owed them a duty of care to monitor and maintain (to design standards) the condition of the stopbank.46[123] I dismiss from consideration allegations concerning duties of care in the conduct of the 1997/1998 LMS review. Likewise modelling of hydraulic capacity of the floodway. All of these would be time-barred, and were not the subject of extensive evidence or submission. As I have said earlier, the plaintiffs' focus is noton construction,47 but on subsequent monitoring and maintenance of the stopbank adjacent to the trestle bridge.[124] I also dismiss allegations relating to the response of the Council to the emergency. Although pleaded, this aspect was but faintly pursued. There was noevidence of any cogency to suggest that the Council's response to these unexpectedand catastrophic floods was other than impeccable. I need not waste time now analysing the nature of the duties they owed in respect of their flood response.[125] So the pertinent question here is simply whether the Council owed the plaintiffs a duty of care in monitoring and maintaining the stopbanks adjacent to the trestle bridge.Submissions[126] The plaintiffs submitted that the Council owed them a duty of care in the monitoring and maintenance of stopbanks, for the following reasons: the Council had a statutory duty to protect and maintain its waterways;48 it was funded by ratepayers, who were a particular identifiable class; ratepayers being levied for flood46 See [79]-[82] above.47 Including reconstruction, there being community consensus to adopt Option 4: see [31]-[35]above.48 Soil Conservation and Rivers Control Act 1941, ss 10, 126, 133.protection purposes were in "an almost contractual relationship with the Council";ratepayers were entitled to assume that the Council would carry out its responsibilities appropriately; and if monitoring and maintenance was not carried out properly at critical areas such as the bridge/stopbank interface, then serious damage was likely (along with significant risk to the community).[127] Turning to issues of policy rather than proximity, the plaintiffs submitted that there were no political or policy issues involved, and that the proposed liability related to purely operational matters. Mr Upton submitted:The Council has assumed responsibility for maintenance and monitoring in circumstances where ratepayers were entitled to assume that the Council has the skills and resources to do so properly. Further, the ratepayers themselves had no capacity to assess the risks nor to directly protect themselves from risks of the present kind.[128] The sole case cited by the plaintiffs was Atlas Properties v Kapiti Coast District Council.49 I have discussed that decision already, at [98].[129] The Council, on the other hand, submitted that what is contended for by the plaintiffs is a novel duty of care. Counsel had not found any decided case in New Zealand where a regional council or catchment board had been held to owe a duty of care to farmers in respect of flooding caused by breach of a stopbank. Citing, in particular, the Court of Appeal decisions in South Pacific Manufacturing Co Ltd v NZ Security Consultants & Investigations Ltd50 and Rolls Royce New Zealand Ltd v Carter Holt Harvey Ltd,51 the Council submitted that the overall consideration must be one of policy. It was submitted that if a duty was imposed in this case, then "itwill open the floodgates to so many claims after every flooding event that the end result would be a massive cost to the community as a whole and obviously significant resources being dedicated to litigation".[130] The Council submitted that it was not correct to view this case as an attack on the operational management of the LMS. The management of that scheme was49 Atlas Properties v Kapiti Coast District Council HC Wellington CP 172/00 19 December 2001,per Durie J.50 South Pacific Manufacturing Co Ltd v NZ Security Consultants and Investigations Ltd [1992] 2NZLR 282 (CA).51 Rolls Royce New Zealand Ltd v Carter Holt Harvey Ltd [2005] 1 NZLR 324 (CA).dictated by the funding available, something voted upon by the community. Thus the case dealt with significant policy and resourcing issues. Ms Macky submitted:It is not for the Courts to override the wishes of the community in determining what level of protection the community is prepared to pay for. The imposition of a duty by the Courts, if it requires greater expenditure than approved by the community, will be a burden to the community by way of increased rates. ... [I]t is not for the Courts to exercise this function but rather the community through implementing policy as envisaged by the Act.Analysis[131] I conclude that a duty of care does exist in respect of monitoring and maintenance of the floodway stopbanks. I reach this conclusion for three reasons:[132] First, there is s 148 of the Soil Conservation and Rivers Control Act 1941.52Two points can be made about s 148:(a) it would be a remarkable consequence if s 148 were to have the effect of excluding causes of action other than negligence, but thatnegligence itself could not then arise. The Council's stanceeffectively would render it immune for all practical purposes from civil liability; and(b) the purpose of s 148 (and its adjacent provisions) is in part to confirm that bodies such as the Council should be liable if they are negligent in the construction or maintenance of stopbanks.[133] Secondly, there is the fact that the Council explicitly undertakes monitoring and maintenance of the stopbanks, and budgets for that activity. A significant percentage of the annual rating of landowners benefiting from the LMS scheme (and therefore paying the lion's share of its cost) is spent on maintenance.53 Council work gangs inspect the banks on a regular basis. No major policy or resource allocation issue arises. The allocation has been made already. The Council monitors and maintains.52 See at [95].53 See at [21] and [34].[134] And it has little choice but to do so. It was common ground among the expert witnesses called for the parties that stopbank security is dependent on good maintenance practices. As Mr David Hamilton, a consulting engineer with particular experience of catchment boards and regional councils, put it:Good practice for a regional council that owns and operates flood control and drainage schemes is to ... provide for maintenance of the scheme to meet defined levels of service.And:A well-run scheme which involves extensive stopbanks would typically involve regular inspections with each part of the stopbanks in the scheme being inspected at least once in every 24 month period or as required as a result of specifically noted issues.[135] It is proper to infer in such circumstances a duty of care in the performance of that operational function. At the very least those who pay rates for maintenance services are proximate.[136] Harm to adjacent landowners between the stopbanks and the Manawatu River to the south, following failure to meet that duty, is wholly foreseeable. I do not understand the Council to have suggested otherwise. In my view the Council had a duty of care to monitor and maintain the stopbanks so that the community could reasonably be assured that they would conduct flood waters in ordinary circumstances. The consequences of failure to do so plainly include significant risks to people as well as to property. Witness the invidious experience of the Stratton family.54 The Council was well placed to undertake the duty. Indeed stopbank monitoring was already a regular responsibility of the local work gang overseer. Broader policy reasons do not exist to negate this duty. Rather, to negate the duty would conflict with the underlying legislation.[137] The proposition advanced by Ms Macky for the Council that this would"open the floodgates to so many claims after a flooding event", causing a "massive cost to the community" is more a reflection of the extent of danger that would arisefrom disregard of the duty of care, than a reason not to impose it. The point is more54 See at [48].relevant to determination of the relevant standard, rather than the existence of a duty, of care.[138] The fact that the community itself determines the extent of maintenance services to be performed will significantly influence, although not determine, theextent of the duty imposed. I will consider that under Issue 3.[139] Thirdly, although the nature of the breach of duty alleged in this case is an omission to repair, landowners in New Zealand may be held to owe a duty to maintain their land and to take positive steps to prevent harm to adjacent landowners resulting from the operation or use of their land. The principle finds expression in cases like Goldman v Hargrave,55 Landon v Rutherford56 and Leakey v National Trust.57[140] The former cases were ones of negligence by omission in failing to respond adequately to a fire (itself not caused by negligence).58 The latter concerned the fall of unstable soils from one hillside property to another lying below. Although Leakeywas brought in nuisance, the discussion of the relevant duty of care is equally transferable to negligence. The Privy Council decision in Goldman demonstrates that proposition, drawing as it does upon authorities in both forms of action. WhatGoldman holds is that a landowner has a general duty of care to a neighbouring occupier, in relation to hazards occurring on that land (and regardless of cause). The duty is to take such steps as are reasonable for a person in the shoes of the landowner to prevent or minimise the risk once the landowner is (or should have been) aware of it.Conclusion[141] To impose a duty of care on the Council in this case, in respect of the monitoring and maintenance of the stopbanks, and in favour of adjacent landowners, is supported by the underlying legislation. And it is orthodox as a matter of common55 Goldman v Hargrave [1967] 1 AC 645 (PC).56 Landon v Rutherford [1951] NZLR 975 (HC).57 Leakey v National Trust [1980] QB 485 (CA).58 See also Wilson & Horton Ltd v Attorney General [1997] 2 NZLR 513 (CA).law. In short, there is sufficient proximity between the Council (as the owner of the stopbanks), and the adjoining landowners and occupiers, that it is just and reasonable that a duty of care to monitor and maintain the stopbanks should exist.[142] I find, therefore, that the Council owed the plaintiffs a duty of care in monitoring and maintaining the floodway stopbank.Issue 3: Was the Council negligent?Standard of care[143] The applicable test in determining whether the Council has breached its duty of care is that set out in a judgment of Venning J in Body Corporate 189855 v North Shore City Council:59The standard is that stated in Askin v Knox [1989] 1 NZLR 248, namely the standard to be regarded as reasonable at the relevant time for the officers carrying out the task in issue. I remind myself that the parties and the Court are approaching the matter with the benefit of hindsight and the knowledge that now exists of the various issues that have contributed to the leaky building crisis.[144] The question is what could reasonably have been expected of the Council and its staff in the period prior to the flood in February 2004. As Heath J said in Body Corporate 188529 v North Shore City Council,60 care must be taken to ensure that, when assessing the standard of care expected from a council and its officers, the bar is not set too high.[145] In particular, the standard should generally reflect constraints the community itself has imposed on the Council in terms of funding. I have already held this affects the scope of the duty of care. Likewise it influences the standard of performance the Council owes those to whom it owes a duty.59 Body Corporate 189855 v North Shore City Council CIV-2005-404-5561 HC Auckland, 25 July 2008 at [75].60 Body Corporate 188529 v North Shore City Council [2008] 3 NZLR 479 at [55].Submissions[146] The plaintiffs' argument was focused very substantially upon a contention that there was a gap between the cement bags on top of the stopbank, and the underside of the trestle bridge. I have noted this point already.61[147] The existence of the gap was the linchpin of the plaintiffs' case. AsMr Upton put it in cross-examination of a Council witness:Messrs Easton and Eveleigh's claim to the Court is on the basis that theproblem started under the bridge and then developed and spread from there.[148] In particular, the stopbank was intended to have a watertight seal between its top and the underside of the bridge. Such a seal was depicted in the original 1958 design drawings. A watertight seal was, said Mr Upton, "central to maintaining the bank's integrity in a design flood when the water in the floodway was intended to lapthe bridge beams".[149] In summary:The plaintiffs say that the stopbank collapse was initiated under the bridge with some sort of failure at that point, the precise mechanism of which is not important[150] The plaintiffs also contended that there were other contributing causes: a narrowing of the stopbank adjacent to the bridge;62 the presence of a raised berm (caused by drain clearings) in the floodway floor upstream of the bridge; and a cycleway ramp intruding into the floodway some 20 metres downstream of the bridge.[151] The plaintiffs' theory of their case was therefore dependent to a verysubstantial degree on sustaining three propositions: (1) that the gap existed; (2) that the presence of the gap was negligent; and (3) that the gap was causative of the ultimate failure of the bank (recognising that it would do them no good if it was simply one of a series of independent causes of the stopbank failure). Propositions61 See at [80].62 Which I have already dismissed, as none of the expert witnesses supported it: see at [80].(1) and (2) must be dealt with under the current Issue 3; proposition (3) is at the heart of Issue 4.[152] Turning to the Council, it devoted considerable effort and evidence to responding to proposition (1). That is, it sought to establish that no gap in fact existed beneath the bridge. That contention turned on evidence given by Mr Graeme Anderson. I discuss Mr Anderson's evidence on this topic later in my judgment.63[153] In the alternative, if a gap existed then the Council's response to proposition(2) was that it had nonetheless taken reasonable care in its management and monitoring of the stopbanks. In particular, by obtaining the Riley report in 1994. The Council submitted that Riley had been instructed to check services through or adjacent to stopbanks, to check the permeability of high priority stopbanks for potential piping failure zones, and to recommend works and management practices to improve the security of the stopbank system. Nothing in the Riley report would have indicated a problem in the vicinity of the trestle bridge. Moreover, the monitoring and maintenance regime implemented by the Council was the subject of evidence. It received the approval of the Council's expert witness, Mr DavidHamilton. Mr Hamilton concluded the Council had acted diligently.[154] Principally, though, the Council's case was focused on proposition (3). That is, it contended that any such gap was not causative of the stopbank failure. I discuss that matter later, under Issue 4.Analysis[155] Each of the three experts called to give evidence gave evidence relevant to the setting of the standard of care. Of the three, Mr David Hamilton had background experience as a former catchment board and regional council engineer that was most relevant to this aspect of the case. Mr Hamilton is now a consulting engineer. But in his previous life he had been chief engineer of two significant catchment boards. His last role, before striking out on his own, was Director of Technical Services at the Otago Regional Council.63 At [166].[156] I have referred already64 to Mr Hamilton's observations that it is good practice for a regional council owning and operating flood control and drainage schemes to maintain the scheme to defined levels of service, and to conduct appropriate reviews of scheme performance. Mr Hamilton considered that the Council in this case had met acceptable standards of technical performance in managing the LMS. Mr Hamilton stated:A well run scheme which includes extensive stopbanks would typically involve regular inspections with each part of the stopbanks in the scheme being inspected at least once in every 24 month period or as required as a result of a specifically noted issue. The evidence I have reviewed of theCouncil's records and the briefs of Alan Cook, Graeme Anderson andGraeme Doull demonstrate a more than appropriate inspection regime was in place. No issues were observed in the vicinity of the Whirokino trestle bridge. I cannot see anything in the documents or evidence indicating shortcomings in the inspection process relative to acceptable standards adopted by other catchment boards and regional councils.Inspection of the Whirokino Trestle Bridge interface of the Moutoa floodway stopbank and the upstream and downstream stopbanks was carried out by experienced personnel within the 12 months prior to the failure. Such inspections did not identify the need for any maintenance work at that location (apart from those programmed). I consider the Horizons Regional Council to have adequately managed its responsibilities in relation to inspections.[157] However, Mr Hamilton was reliant on evidence by Council witnesses (in particular Mr Graeme Anderson) that the Council had inspected the seal between the bridge and stopbank. And that the upshot of that inspection was that no significant gap between the cement bag infill and the bridge structure existed.[158] Those assertions were however challenged strongly in evidence.(1) Was there a gap between the underside of the trestle bridge and the top of the stopbank?[159] This question occupied a significant proportion of the evidence.[160] There were three relevant eye-witnesses: Mr Stuart Barber, Mr Graeme Anderson and Mr Graham Doull. The latter two were called by the Council.64 At [134].[161] As will be recalled, Mr Doull is a senior design engineer employed by the Council.65 It seems that on 2 August 2002, while inspecting the implementation of the Option 4 works programme, he inspected a site near the trestle bridge. It was one of four sites he inspected that day. Candidly, Mr Doull admitted not spending long at the trestle bridge site. The work required there was at best minor, and he was focused on another site. He said, "I therefore did not spend any time looking forother problems". He did not notice anything about the bagging under the bridge. Insum, Mr Doull's evidence is that he did not see anything. But nor, in truth, was helooking closely. I put his evidence aside.[162] Mr Stuart Barber we have also met before.66 He is a local farmer. He farms north of the northern stopbank of the Moutoa floodway. He has farmed there all his life. He has been interested in the Moutoa floodway since it was constructed in the early 1960s. He told the Court how he skipped school to watch drag lines forming the stopbanks on the first day of works on the floodway. For some 25 years he leased grazing land in the floodway. He was for 30 years a member of the local drainage board. More recently he has been a member and chairman of the Council liaison committee concerned with drainage in that vicinity.[163] He too inspected the bridge at about the time repairs were being carried out to the stopbank. He dates his visit as occurring in the second half of 2003 – perhaps ayear after Mr Doull's visit. I consider it likely to have been June 2003, as Mr Cook'sevidence suggests that is when the repair work was carried out.67 Mr Barber told the Court that he spoke to the workmen. He watched what they were doing with interest. He walked upstream on the outer side of the southern stopbank:As I did so I walked under the bridge, climbed up the southern side of the southern bank and looked over the top of the bank. There was a gap of approximately 150 millimetres between the underside of the bridge and the top of the cement bags. I could see clearly the next trestle of the bridge through the gap.He recalled the crown of his Akubra hat resting against the underside of the bridge as he looked through the gap.65 See at [28].66 At [55].67 See at [29].[164] Mr Barber was cross-examined at some length by Mr Heaney, when first called and subsequently when recalled by the plaintiffs. I found Mr Barber to be a reliable witness. His evidence about the circumstances in which he came to look at the gap had to my mind a degree of colour confirming credibility.[165] The third witness was Mr Graeme Anderson. Prior to 2006 he was an engineering works supervisor for the Council. He was in charge of the Shannon work gang. Part of his responsibilities included regular inspections of the stopbanksin the vicinity of the Moutoa floodway. He said it was his job to "check the stopbanks on a regular basis to ensure there were no obvious points of failure".Mr Anderson said he checked the stopbanks at least once every 4-6 weeks. Thus he would have checked them within six weeks of the 16/17 February 2004 event. His modus operandi was to drive along the tops of the stopbanks checking both sides. Mr Anderson claimed he would always get out at the trestle bridge and check that point. His particular concern was rabbit activity, and rabbit burrows in the banks. He said that:I was and am satisfied that the stopbank and the trestle bridge was perfectly intact at the time of the floods.[166] Under cross-examination Mr Anderson attempted to bolster his written evidence. He said that he had actually walked up under the bridge and had done a visual inspection of the bags, and he was certain there was no gap. Given that he had no notes of his inspections, that his process was habitual rather than directed at a specific event, and that such focus as he had was on rabbit burrows, I find that additional evidence less than wholly credible.[167] Mr Anderson also gave evidence, under re-examination, of having supervised works in the 1980s to insert additional cement bags under the stopbank where subsidence had occurred. That evidence I do accept, however. It shows that the Council was conscious of the need to maintain, to the extent it could through cement bags, a watertight seal between the bridge and the stopbank. A number of witnesses for the Council confirmed that necessity. I will return to that point later.6868 At [180-183].[168] Having heard these witnesses, I advised counsel of my provisional finding that there was indeed a gap above the cement bags on the stopbank. I did so toensure that the experts (who were to convene shortly thereafter in a "hot-tub") did so on a sound factual basis. I did not wish to be confronted by Spencer's tragedy of abeautiful theory being spoiled by inconvenient facts. In closing, the Council"accepted that there was probably a gap between the sandbags and the underside of the bridge".[169] As a matter of fact I find that there was a gap of approximately 150 millimetres above the cement bags topping the stopbank crest, under the trestle bridge, on the southern side of the floodway.(2) Did the gap constitute a breach of the Council's duty of care?[170] As we have seen, the underside of the trestle bridge projected beneath the expected level of a 1 in 100 year flood.69 The top of the bridge deck was at the same level as the top of the stopbank: 5.2 metres above mean sea level. The underside of the bridge deck was at 4.9 metres.70 The 1 in 100 year flood level at the bridge was at 4.63 metres. Allowing the required 450 millimetres freeboard, a minimum stopbank level at the bridge of 5.08 metres was needed. It follows that an effective seal below the bridge deck was necessary simply to maintain the intended freeboardabove the expected flood levels at that point.[171] The effect of the bridge beams protruding 480 millimetres below the bridge deck, and 110 millimetres into the expected 1 in 100 year flood waters, created its own issues. First, the intrusion represented a constraint on the free movement of the flood waters, creating a "pulsing, sucking, wave effect" as the plaintiffs' expert,Mr Gary Williams put it. As the Sutherland report put it:One complicating factor lay in the upstream water level being below the soffit of the bridge beams. This surcharge would have induced a pulsing into the flow and caused increased velocities under the bridge and thus along the stopbank face.69 At [18].70 And of course the beams projected a further 0.48 metres downwards: see at [18](b) above.As Mr Noel Luxford, an expert witness for the Council, put it, it would "create a disturbed water flow beneath the bridge".[172] Secondly, the low bridge level would (as the Sutherland report also noted), result in the collection of debris. This would add to the degree of water flow disturbance, and could threaten both the integrity of the bridge and the adjacent stopbank. One of the tasks that Mr Bonis and his colleague were attending to on the Tuesday morning before the catastrophic stopbank failure was shifting debris that had built up against the bridge.[173] Thirdly, the bridge beams and debris would cause a measure of wave displacement, fanning back against the stopbank immediately upstream of the bridge, and also beneath the bridge. As Mr Williams put it:Bridges or concrete structures through stopbanks are critical items, so water will go beside any concrete and scour away the earth because it can't scouraway the concrete obviously or the ... cement bags, so they are more solid [and] a scour tends to take place beside those sorts of structures.However, I accept that the risk of deflection scouring is relative to water flow velocity. The very flat gradient at the bridge (1 in 6,000) meant that even with a massive flood, the water flow did not have a particularly high velocity.71[174] In these unusual circumstances it was important that the freeboard level beneath the intruding bridge be maintained by an effective seal. The expert witnesses substantially agreed on this proposition[175] Mr Gary Williams, a very experienced consulting engineer, with particular expertise in water and soil matters (especially river management and flood mitigation) gave evidence for the plaintiff. He observed:The floodwater was actually designed to be up onto the bridge. So it essentially had vulnerability because of that. And therefore the question of whether the water seal around the bridge and onto the stopbank was a critical matter at this site.71 See at [5].[176] Mr Hamilton, whose qualifications I have referred to before,72 essentially agreed in general terms:Mr Upton: [T]hat design, of necessity, requires a good watertight seal between the bridge and the stopbank interfaces, correct?Mr Hamilton: I agree.[177] Mr Noel Luxford is a very experienced consulting geotechnical engineer. He gave evidence for the Council. Mr Luxford took the view that sealing was not asimportant as maintaining the integrity of what he called the "freeboard zone". In myview, that is something of a distinction without a difference in this case. The required stopbank level at the bridge was at least 5.08 metres above mean sea level; the underside of the bridge deck was lower, at 4.9 metres. To maintain freeboard integrity an effective seal was required beneath the bridge. Such a seal became all the more important given that the bridge protruded into the 1 in 100 year floodwater level (which was the relevant design standard).[178] Mr Luxford noted also that the cement bags, while a common and perfectly acceptable solution in his view, would not offer a perfect seal. The issue was not the bags themselves, which would harden into rock-like form, but the ability of water to work its way around the bags. Just as if they were indeed rocks, piled against eachother. In short, Mr Luxford's view was that reasonable practice did not require aperfect seal.[179] An essential question, which I will come to under the issue of causation, is whether, at the time of the catastrophic collapse downstream (at about 6.30 am on the Tuesday morning), the cement bags were still in place beneath the bridge.[180] Despite Mr Luxford's reservations, it was I think relatively common groundby the end of the case that good maintenance practice for stopbanks in such a situation did require a substantially effective watertight seal. First, the 1958 design drawings for the Moutoa floodway showed such a seal. Secondly, as I have shown at [170] and [177], such a seal was necessary to maintain the 450 millimetre design72 At [155].freeboard above the 1 in 100 year flood level. Thirdly, the Sutherland report recommended the installation of a waterproof butynol liner sealing the area adjacent to and beneath the bridge, although I accept that it did so with the benefit of hindsight. Fourthly, as I have said, the experts predominantly agreed on the point. Fifthly, the Council devoted a significant effort in this case to establish the absenceof a gap. Unsuccessfully, as it turned out. But its devotion to that cause emphasised its significance, and suggested that the failure to maintain an effective seal between the bridge and the cement bags might well be a breach of duty of care.[181] The Council's works supervisor, Mr Anderson, certainly saw it that way:Mr Upton: But if there was a gap between the underside of the bridge and the top of the stopbank, would that have been of any concern to you?Mr Anderson: Oh yes, of course.Mr Upton: Why was that?Mr Anderson: Well because it would have to be repaired. I mean, there's apossibility of water going through there but it was huge ahh, the sandbagging itself was quite a big set-up. I mean they were the full width of the bridge and they were probably 6 to 8 bags wide and, as I say, right up under the beams.[182] Mr Doull, the senior engineer responsible for the LMS, took a similar view.He accepted that a "proper seal between the stopbank and the underside of the deck was vital to the integrity of the stopbank system". The following exchange tookplace between the Court and Mr Doull:Court: I think you accepted in questions from Mr Upton that it was critical, or crucial, that there be a seal then beneath the bridge?Mr Doull: Yes.Court: I assume that's because, if we look at the design criteria, it providesthat the top of the stopbank is, as you've just said to Mr Heaney, at least atthe deck level?Mr Doull: Yes.Court: And so, obviously, below the bridge it would be beneath that, unless you sealed it?Mr Doull: That's correct.Court: ... The reason why it's crucial to maintain that seal is, what? To prevent the flow through, where that would be clearly at a level below the rest of the stopbank system?Mr Doull: Yes.Court: And also below the top water level for which it's designed?Mr Doull: Um, yes, yes, Your Honour.Court: So that seal would be necessary to prevent, in effect, a gate in the crest of the stopbank?Mr Doull: Yes, it's necessary to prevent flow through it, because once the flow gets onto the land side of the stopbank we, we don't know what damageit could do, but we would rather it didn't happen.Court: And presumably it would also be necessary to ensure that, if you had in effect created a gate through the design level of the stopbank, that would be a thorough and strong seal, because we're dealing with very substantial water forces here, aren't we?Mr Doull: Well, the water force would not be that great, because, well ...you'd have to assume it could be as high as the stopbank.[183] As noted earlier,73 the Council made a good deal of the fact that it had commissioned a report from Riley Consultants Ltd in 1994. The Riley report had not identified a gap in the effective seal beneath the bridge. Much evidence was also devoted to showing that the cement bags would largely have settled in place by 1994, so that a gap should have been as visible then to Riley as to the Council'sworkers in 2004.[184] Whether or not that was the case, the focus of the Riley report was on the integrity of the constituent materials of the stopbanks. What the Council obtainedfrom Riley was a geotechnical study. It is true that the Council's brief included some non-geotechnical issues. But the final report seems to have adopted a narrower scope, confining itself to geotechnical matters. The report did not expressly address the effects of intruding services. Nor did it recommend any works or management practices to improve the stopbank system. The report is perfectly clear on its face that its focus is a geotechnical study of the then-present condition of the stopbanks. If the Council expected it to address other matters, it should have identified that the report did not do so. It cannot now say that it asked for a report on such matters, and73 At [153].should therefore be held to have acted responsibly, if it did not listen for the answer (or note its absence).[185] In light of this evidence, I find the failure of the Council to identify and remedy the gap between the cement bags and the underside of the bridge deck, in the course of its routine operational monitoring and maintenance of the stopbanks, was in breach of its duty of care to the plaintiffs.(3) Other possible breaches of the Council's duty of care regarding monitoringand maintenance[186] Two other potential sources of negligent monitoring and maintenance of the stopbanks were identified as potentially causative of the stopbank failure: the effect of a drain (and its clearings) upstream of the bridge, and a cycleway ramp some 10 metres downstream of the bridge. These were very much "also-rans" in theplaintiffs' case. And rightly so.[187] Drain: A number of drains cross the floodway. Their function is to carry water out in times of normal precipitation. One of these drains is just upstream of the bridge. In the manner of drain construction since time immemorial, the drain clearings were piled alongside the drain. The clearings formed a low berm in the floodway floor. Mr Williams, with due caution, suggested that the clearings added complexity to the land form geometry upstream of the bridge. And that this would have increased flow variation and the generation of scouring eddies and vortices at and under the bridge.[188] In cross-examination Mr Williams accepted that the drain berm could havehad only a minor effect. It would, at most, have been "a small factor" in generatingturbulence and increasing velocity. Mr Hamilton's evidence was very exact: the drain clearings would have caused a slight increase in water level immediately upstream of the berm, and a slight increase in flow velocity as the water passed over the berm. But the speed increase would have been wholly lost by the time the water reached the bridge.[189] On the evidence before me, therefore, I could not have found the drain causative of the stopbank failure. Nor would I have found that a foreseeable consequence of the drain was erosion of the stopbank. Accordingly, even assumingthe deposition of the drain clearings amounted to "monitoring and maintenance", Iwould not have found that to constitute a breach of duty.[190] Cycleway: Downstream of the bridge, some 10 metres or so distant, a cycleway runs parallel to the highway. Of course, cyclists must mount the crest of the stopbank to go upon their journey. So ramps were built on either side.[191] Mr Williams suggested, and again with caution, that the ramp in the floodway might have contributed to eddying. But, he said, he did not know how much erosioncould be said to have resulted. Mr Hamilton's evidence was that the cycleway rampwould have resulted in a slight generation of vortices at the point of intrusion into the flood waters. But it would not have affected things as far back as the bridge.[192] The construction of the ramp, which lies beyond the scope of maintenance and monitoring, was at most a potential contributor to the downstream failure. But there was simply insufficient evidence for me to conclude that, but for the construction of the cycleway, the floodway stopbank would not have failed at that point. Viewed with foresight, let alone hindsight, I would not have found it foreseeable that the cycleway ramp would cause erosion of the stopbank.[193] Accordingly, I discount the breach allegations relating to the cycleway and drain.Conclusion[194] I conclude that the failure of the Council to identify and remedy the gap between the cement bags topping the stopbank, and the underside of the bridge, in the course of its routine monitoring and maintenance of stopbanks, was in breach of its duty of care to the plaintiffs. In that respect alone I find the Council to have acted negligently.Issue 4: Did the Council's negligence cause the plaintiffs' loss?Causation[195] A negligent defendant will only be liable if its conduct causes damage. Thedefendant's action must be a substantial and material cause: Johnson v Watson.74That is, it "must have had a real influence on the occurrence of the loss ordamage".75 The Courts apply a "but for" test.76 Would the loss or damage have occurred but for the negligent act or omission? A robust approach is taken. As Glazebrook J said in Accident Compensation Corporation v Ambros:77It must, however, always be borne in mind that there must be sufficient material pointing to proof of causation on the balance of probabilities for a court to draw even a robust inference on causation. Risk of causation does not suffice.[196] It is on this issue that the plaintiffs' claim runs into greatest difficulty.Submissions[197] The plaintiffs submitted that there were not two independent causes of thestopbank failure, but that "the whole of the events at, around and under the bridge onthe night of 16/17 February 2004 were intimately connected and all part of the samecausative incident". The initial flow from the floodway "would have been throughthe gap between the bags and the underside of the bridge and through any gaps that opened up between the bags as a result of settlement". The stopbank would haveeroded along the floodway face and (as a result of overflows) along the southern face of the stopbank outside the floodway. This caused the bank to weaken and breach.[198] The most likely explanation for the breach at the bridge was said to be that scouring at the bridge had created a gap in the stopbank on both sides of the bridgeand "was starting to erode the base of the stopbank to the side of and under the concrete bags". The plaintiffs referred here in particular to Mr Doug Easton's74 Johnson v Watson [2003] 1 NZLR 626 (CA).75 Ibid at [18].76 Accident Compensation Corporation v Ambros [2008] 1 NZLR 340 (CA).77 Ibid, at [70].evidence of water pouring through a breach immediately upstream of the bridge. It was also submitted that I should not find that there was a separate downstreambreach. Instead it was probable that there had been a progressive breach, both upstream and downstream, emanating from the conditions under the bridge.[199] The Council, on the other hand, contended that the cause of the failure, initially, was probably water working its way through loose (perhaps hand compacted) materials immediately upstream of the bridge. It was this erosion initially that allowed substantial volumes of water into the Moutoa Basin. On the other hand, the Council submitted, the sandbags under the trestle bridge were"almost certainly still intact" at that stage.[200] The Council also submitted that over-topping downstream of the bridge resulted in a sequence of failures near the cycleway, and again between the cycleway and the bridge. But, submitted the Council, there was no evidence to suggest that any of these failures were connected to the gap under the bridge, on which the plaintiffs had built their case.Analysis[201] To set the scene, I should observe that I was faced with somewhat diametrically opposed evidence. At least to begin with.(1) Mr Gary Williams[202] Mr Williams maintained that the most logical cause of the failure of the stopbank in the vicinity of the trestle bridge was water flowing through the gap, eroding the stopbank, and causing progressive failure both upstream and downstream of the initial breach:When the water started lapping onto the bridge, and up against the beams, there would no longer be a free air surface under the bridge and pressure flow would have developed. This, though, requires some heading up or rise in water level to drive the pressure flow, and there is a loss of flow efficiency at this point. A surging in the surface levels takes place under these conditions, which generates pulses, waves and eddying in the water. This surface fluctuation, eddying and wash effect would have interacted with thecomplex beam arrangement of the bridge, giving rise to wave impact and slosh effects, and forcing water in different directions. Overflows would, therefore, have occurred through the gap under the deck slab and beams at the stopbank. Once pressure flow had developed at the bridge, overflow under the bridge would have become inevitable....Once floodwaters in the floodway had reached the underside of the bridge, stopbank failure of the bridge may have been inevitable – without any other aggravating influence – because of the overtopping of the sandbag areas under the bridge.[203] Although expressing his views in evidence with a greater degree of dogmatism than the other expert witnesses, Mr Williams did qualify his views in three important respects.[204] First, Mr Williams accepted that he could not be certain about the source of the flow of water in the basin reported by Messrs Stratton and Doug Easton in the early hours of Tuesday morning. Mr Williams accepted that these had to have come from around the bridge. He noted, correctly, that the eye-witnesses' evidence was not consistent. His "best assessment" was that it came from under the bridge.[205] In this respect I consider Mr Williams had been influenced in his opinion, and thus understandably misled, by the initial evidence of Mr Jamieson. Mr Jamieson's initial observation of water "flowing over the top of the stopbank under the bridge" –and not on either side – "approximately half a metre to 1 metre wide and 20 centimetres deep" was later significantly qualified in cross-examination. Then heaccepted that what he had seen at that stage was only a "slow trickle". This was, ofcourse, at 5.00 pm on Monday evening – three hours or so before the peak floodwater level was reached.[206] Secondly, the experts caucused before giving evidence. The caucus produced a useful joint report, agreeing on a number of technical issues. Then the evidence that followed was given in a panel format – otherwise known as a "hot tub". Boththe caucusing and panel processes resulted in a greater degree of consensus than would have been the case had evidence been given serially. It also reined in any predisposition to rigid adherence to briefs. That was important because in some keyareas (e.g. Mr Jamieson's evidence, and the issue over whether there was indeed agap), things had been clarified by factual witnesses before the experts' turn arose. Inmy view, it is always preferable for expert witnesses to follow fact witnesses,whether or not a panel (or "hot tub") approach is adopted.[207] In this case a critically important concession, and point of consensus, emerged during the caucusing. It was that all experts agreed:... that the sandbags may still have been in place at the time of the catastrophic failure. [i.e. at 6.30 am on Tuesday morning].[208] Thus it followed that, with the cement bags potentially still in place at 6.30 am, the large amounts of water in the basin at 2.00 – 3.00 am had to have come from an over-topping or breach either upstream or downstream of the bridge. It could not possibly have come just from water forcing itself through the narrow gap above the bags (even allowing for additional volumes flowing around the bags). That couldnot have been sufficient to cause the huge flow which "raced like a wave" across Mr Stratton's farm at 3.00 am.[209] The third respect in which Mr Williams qualified his views was to withdraw his earlier suggestion that the narrowing of the stopbank under the bridge may have made the area more prone to scour and erosion. The experts also agreed this point intheir joint caucus report. They said, "we do not consider that the smaller cross-section of the stopbank under the bridge was a contributing factor to the failure".(2) Mr Noel Luxford[210] The first point Mr Luxford made was that even allowing for the gap, reducing the effective freeboard beneath the bridge, the cement bag level was still slightly higher than the peak floodwater level at the bridge. The gap lay between the underside of the bridge (approximately 4.9 metres) and the top of the cement bags (approximately 4.75 metres). The water level at the peak of the flood was agreed as being 4.65 metres at the point it met the bridge.[211] It was not suggested by Mr Luxford that water would not escape over the top as a result of slop – given the disturbed water patterns beneath the bridge caused by the intruding beams and debris. Plainly it would, and in reasonably significantquantities. But in his view there would not be any continuous pouring of water over the gap. It was more a case of water bypassing between the bags – as demonstrated by Mr Jamieson's observations of a "slow trickle" at 5.00 pm on the Mondayevening (when the water was not of course yet at its peak).[212] Mr Luxford also concluded that even if there were gaps between the cementbags, "any flow through those gaps would have been very unlikely to have displaced what would by then have effectively been weak rocks moulded into each other". AsI have already noted, the experts all agreed that the bags may still have been in place at 6.30 am, just before the catastrophic downstream failure.[213] Mr Luxford also considered that the cement bags should "easily withstandwater flowing over the top of them even if there was a gap between them and the underside of the bridge". In good part this was due to the slow velocity of thefloodwaters, due to the shallow gradient of the floodway. Thus he opined:I would be very surprised if the failure sequence was due to erosion anddisplacement of those concrete "rocks" causing failure. It would be much more likely in my opinion that failure would emanate at some other point on the stopbanks.[214] Mr Luxford said:I cannot tell why the stopbank failed downstream of the bridge and from the evidence I have seen I doubt if anyone else can. I understand there has been some suggestion that the surging under the bridge or interface caused by the bridge was the trigger point for the failure of the sandbag portion of the stopbank under the bridge. That seems to me to be unlikely because the stopbank on the right hand side downstream of the bridge did not fail and I would have expected the effects of the waterway under the flood event both beneath the bridge and downstream to be the same as the left hand side and yet no failure was experienced on the right hand side. I suspect that it must have been an unseen weak point within the stopbank downstream of the bridge which eventually initiated failure.In my opinion it is unlikely that failure of the southern stopbank on 17 February 2004 would have commenced by displacing the sandbags under the Whirokino trestle bridge. It is much more likely that failure would have been initiated at the point within the silt and sand fill forming the stopbank material either side of the trestle bridge.[215] In panel evidence Mr Luxford expanded on what the "weak points" might have been. In particular he now focused on the fact witnesses' evidence of:(a) upstream breach – i.e. the evidence of Mr Doug Easton, Mr Richard Barber and Mr Stuart Barber. This confirmed the presence of water flowing over the stopbank upstream of the bridge from 5.30 am or thereabouts on the Tuesday morning. Indeed, probably much earliergiven Mr Stratton's evidence. Mr Doug Easton's evidence wasparticularly notable: he was standing to the south of the stopbank andcould see "bits of the stopbank upstream of the bridge breaking off";78and(b) separate downstream breach – i.e. the evidence of Mr Richard Barber, Mr Stuart Barber, Mr Owen Bonis and Mr Graeme Anderson. This confirmed a distinct breach before 6.00 am on the downstream side of the bridge. That is, ahead in time of the catastrophic failure in the same vicinity at 6.30 am. Understandably after the passage of seven years, their evidence as to the location of that breach varied. But the majority of these witnesses put the breach at a point remote to the bridge. Mr Anderson put it 7-8 metres downstream; Mr Bonis and MrStuart Barber rather closer (although I found Mr Barber's evidence onlocation equivocal in the end). As noted before,79 Mr Richard Barber was not questioned about location.[216] Considering these matters, Mr Luxford opined that it was possible that the bridge (which of course pre-dated the construction of the stopbanks) had caused difficulties for those constructing the banks in the early 1960s. In particular in compacting the fill immediately adjacent to the bridge. As a result, it was possible that the stopbank in that location would have contained voids due to the fill being relatively loosely compacted. Here the stopbank may have been prone to "piping" inthe way described at [26]. Mr Luxford observed:At the same time we would have seen water saturating the stopbank materials and coming through any voids. This is when I think internal erosion would have been occurring in the stopbank materials completely separate from any influence of the sandbags. Seepage connected with the existence of the trestle bridge/sandbag interface material could also have78 See at [51].79 At [53].existed because it would have been difficult to achieve ideal compaction of the stopbank materials particularly at the interface between the bridge beams and the stopbank and in places under the soffit of the deck of the bridge. Even with the topping of the stopbank undertaken by Horizons [i.e. in 2003] there would still have been some voids left in those natural stopbank materials which would have enabled the water to traverse through the natural stopbank materials. Weak points will have been created and in places fine materials would be washed out giving rise to the risk of failure at the point of those weaknesses.This failure probably occurred because the original stopbank material settled over time and contained voids which allowed water to penetrate and traverse through so as to weaken the stopbank in the vicinity of the catastrophic failure zone. We do not know and nor will we ever know how that water entered the stopbank. It could have had its origin in a weak compaction point or some extraneous material within the original stopbank. There could have been a number of entry points for water to eventually find its way to the centre of the catastrophic failure zone. The bridge being where it was may have had an influence because it would have created some difficulties in compaction. Such a mechanism is unconnected with any voids and gaps between the sandbags and the bridge.[217] Mr Luxford pointed out (and I agree) that the Council would have had no reason to appreciate these potential weaknesses. None had been identified by the 1994 Riley report.80 That had not identified any voids in the southern stopbank in the vicinity of the bridge, despite bore holes having been drilled in the stopbank within 200m of the bridge, both upstream and downstream. Riley in fact identified potential issues in the northern stopbank, near the bridge. That was because that stopbank incorporated sandhill material.81 But the northern bank held fast in the flood.(3) Mr David Hamilton[218] Mr Hamilton also rejected Mr Williams' theory of a breach "emanating" from the gap under the bridge. He concluded that the critical breach was downstream ofthe bridge (in accordance with the fact witnesses' evidence). And that (as is normal)it would have spread laterally both up and downstream. As he put it:When a breach occurs there will normally be some lateral spread in both upstream and downstream directions. As the breach develops the breach widening will occur to a greater extent in the upstream direction due to the downcutting and headwards erosion of the fill (given similar bank materials80 See [24]-[25].81 See at [25].in both directions). The actual breach is therefore most likely to have occurred more than 6 metres downstream of the bridge centreline.[219] Mr Hamilton considered Mr Luxford's suggested mode of failure "logical and sensible", and that it provided a "reasonable explanation of the sequence of events". Both Mr Hamilton and Mr Luxford considered that the catastrophic failureat 6.30 am was caused by an unseen weak point downstream of the bridge. What that was they could not say. The flood had washed that evidence away. It was not likely to have been the cycleway ramp. For a brief period Mr Hamilton thought it might have been an old telecommunications duct running through the stopbank at the extreme downstream end of the breach. But he abandoned that view during the panel discussion. It would have been inconsistent with his overriding theory of a breach working both ways from the weak point.(4) Assessment of the evidence[220] The burden of proof as to causation, in accordance with the principles at [195] above, lies throughout on the plaintiffs. They must show on the balance of probabilities that, but for the negligently overlooked gap between the underside of the bridge and the cement bags, the Moutoa basin would not have been inundated by the February 2004 flood.[221] I do not consider that the plaintiffs are able to discharge that burden. Following the foregoing review of the evidence, my reasons can be stated succinctly:(a) It is clear that by about 5.30 am on Tuesday 17 February 2004 the stopbank had eroded significantly upstream of the bridge. A number of witnesses gave evidence of this, but the clearest evidence was from Mr Doug Easton, a witness called by the plaintiffs themselves.82Mr Easton saw water pouring through the bank on the upstream sideof the bridge, and "bits of the stopbank upstream of the bridge breaking off as the water scoured it away".82 Although Messrs Richard Barber and Stuart Barber likewise gave evidence to this effect.(b) The expert evidence did not establish any convincing link between this initial upstream breach and the existence of the 150 millimetre gap between the cement bags and the underside of the bridge, further downstream. In this respect the plaintiff's theory, restated at [197]- [198] above, was profoundly unsatisfactory. On the one hand, it recognised the critical importance of the evidence of the upstreamfailure, attributing it to "scouring action" at the bridge. But its evidence could not connect that initial failure to the actionable gap beneath the bridge. In other words, it could not explain it assomething that had "emanated" from the gap. But nothing apart from the gap had been shown to be actionable.(c) Likewise, by early Tuesday morning, a significant breach was occurring downstream of the bridge. The exact location of that, after so many years, is in dispute. But I am satisfied that the evidence of witnesses called for both sides identified the existence of such a breach. It also appears likely that the initial downstream breach did not reach continuously back to the bridge. That is, there was still some intact stopbank between the bridge and the initial downstream breach. Again, that suggests there was not a continuous failure of the stopbank originating at the gap.(d) The 150 millimetre gap would still have been above the maximum water level during the flood, putting to one side the disturbed water patterns beneath the beams. Of course I do not put those effects aside at all. But I do consider that what was likely to have occurred under the bridge was splash and slop through the gap, rather than a continuous erosive overflow.(e) The preceding conclusions are then reinforced very substantially by the joint position taken by the experts that as at the catastrophic failure downstream, at 6.30 am on Tuesday 17 February 2004, the cement bags may well still have been intact beneath the bridge. Thatjoint assessment severely undermines the plaintiffs' causation theoryof a failure emanating from the gap.(f) Finally, while the exact cause of the failure is not now known, we do know that this was a flood event of a magnitude that exceeded the design standard of the LMS. A standard that the community had bought into in approving Option 4. As I said earlier, this flood event was always going to challenge the capacity of the floodway and river system to cope. The fact that ultimately they did not cannot be attributed with any clarity to the limited deficiency identified in theCouncil's maintenance processes.[222] I therefore agree with the tenor of the evidence given by the experts called by the Council that it was unlikely that the gap beneath the bridge caused the catastrophic failures that occurred to the stopbank both upstream and downstream of the bridge. The gap was insufficiently material to cause those failures. It is more probable than not that those failures were caused by factors independent of the gap, exposed in the course of an exceptional 1 in 110 year, over-standard weather event. And, that being so, it is more probable than not that the Moutoa basin would have flooded to exactly the same extent on Tuesday 17 February 2004, had the gap not been there.[223] At this juncture, therefore, the plaintiffs' claim must fail.Conclusion[224] For the foregoing reasons, I find:(a) The effect of s 148(1) of the Soil Conservation and Rivers Control Act 1941 is that claims against the Council arising from breach of the Moutoa floodway stopbank can be maintained only in negligence.(b) Reinforced by that same provision, the Council owed the plaintiffs a duty of care in monitoring and maintaining the floodway stopbanks.(c) The central and overwhelming focus of the plaintiffs' case was thatthe Council had breached that duty of care by failing to identify and repair a gap above the cement bags topping the stopbank crest, under the trestle bridge on the southern side of the floodway.(d) As a matter of fact there was indeed a gap of approximately 150 millimetres in that location.(e) The failure of the Council to identify and remedy that gap, in the course of its routine monitoring and maintenance of the stopbanks, was in breach of its duty of care to the plaintiffs.(f) In that respect, alone, I find the Council to have acted negligently.(g) The plaintiffs however failed to prove on the balance of probabilities that the presence of the gap caused the catastrophic failures that occurred to the stopbank. Those failures, both upstream and downstream of the bridge, were more probably caused by factors independent of the gap.(h) Accordingly, it is more probable than not that the floods that damagedthe plaintiffs' crops would have occurred to exactly the same extenthad the gap not been there.Disposition[225] Judgment is entered for the defendant.[226] The defendant is entitled to costs on a category 2 basis. If the parties cannot agree costs within 15 working days, the defendant is to file a memorandum within a further 5 working days. The plaintiffs are to respond within a further 5 working days.[227] I thank counsel for their assistance.Stephen Kós JSolicitors:Wadham Goodman, Palmerston North for PlaintiffsHeaney & Co, Auckland for Defendant