BEFORE THE SPECIAL TRIBUNAL FOR THE NGARURORO AND CLIVE RIVERS WATER CONSERVATION ORDER
AT NAPIER
IN THE MATTER of the Resource Management Act 1991 (“Act”)
AND
IN THE MATTER of a Special Tribunal appointed under s202 of the Act to consider an application for a Water Conservation Order
THE SPECIAL TRIBUNAL: Richard Fowler (Chair) Alec Neill (Member) Dr Roger Maaka (Member) Dr Ngaire Phillips (Member) John McCliskie (Member)
STATEMENT OF EVIDENCE OF PETER CALLANDER ON BEHALF OF THE HAWKE’S BAY WINEGROWERS’ ASSOCIATION & GIMBLETT GRAVELS WINEGROWERS’ ASSOCIATION
STAGE 2 HEARING
25 JANUARY 2019
Counsel instructed: Solicitors acting:
J D K Gardner-Hopkins Phone: 04 889 2776 Alison McEwan [email protected] Phone: 06 835 8939 PO Box 25-160 Fax: 06 835 3712 WELLINGTON PO Box 446 NAPIER
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INTRODUCTION
1. My name is Peter Francis Callander and I have been a Director of Pattle Delamore Partners Limited (PDP) since 1997. I hold the qualifications of BSc (Geology) from the University of Auckland and MSc (Earth Sciences) from the University of Waterloo (Canada). I am a member of the New Zealand Hydrological Society, Water NZ and the USA based National Ground Water Association. I also hold a current certificate for “Making Good Decisions” and serve as an Independent Commissioner on RMA hearings from time to time. I have over 25 years of experience as an environmental scientist specialising in groundwater and surface water resources. Prior to my employment at PDP, I had been employed for seven years by the Canterbury Regional Council (ECan) and its predecessor the North Canterbury Catchment Board.
2. I have particular experience in the management of water resources. This has included work on numerous projects where I have modelled and advised on the management of water quality impacts associated with irrigation including work for the Hurunui Water Project, Waimakariri Irrigation Scheme, Rangitata South Irrigation, Barrhill-Chertsey Irrigation, the Southern Valleys Irrigation Scheme and Wairau Valley Water Enhancement Scheme. I have also reviewed work completed by other parties for the proposed Central Plains irrigation scheme (on behalf of the Christchurch City Council and others) and applications for irrigated land use change in the Mackenzie basin (on behalf of Meridian Energy). I have also been involved in many projects relating to groundwater- surface water interaction and was the principal author of the stream depletion guidelines prepared for the Canterbury Regional Council and the sea water intrusion guidelines, both of which have been used nationally as guideline documents. I am also involved in the assessment of contamination risks for drinking-water supply bores across New Zealand in light of the August 2016 Havelock North contamination incident.
3. For this hearing I have been asked by the Gimblett Gravels Winegrowers Association Incorporated (GGWA) and the Hawke’s Bay Winegrowers Associations Inc (HBWG) to provide comment on clause 11 from version
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3 of the “Draft Ngaruroro River and Clive River Water Conservation Order” and the implications it might have on the GWWA and HBWG members. Clause 11 reads as follows:
11. Requirement to protect water quality
No resource consent may be granted or rule included in a regional plan authorising the discharge of contaminants onto land or into waters specified in Schedules 1, 2 or 3 that will cause, either by itself or in combination with any existing consents, activities or rules, the limits specified in Schedule 5 to be exceeded.
This clause does not restrict a regional plan from imposing water quality standards that set more conservative limits.
4. I have read and am familiar with the Environment Court’s Code of Conduct for Expert Witnesses, contained in the Environment Court Practice Note 2014, and agree to comply with it. My qualifications as an expert are set out above. Other than where I state that I am relying on the advice of another person, I confirm that the issues addressed in this statement of evidence are within my area of expertise. I have not omitted to consider material facts known to me that might alter or detract from the opinions that I express.
5. In my evidence I will provide the following:
5.1 Comment on concerns regarding clause 11 of the draft WCO.
5.2 An overview description of the hydrogeological setting of the area where the GGWA operate relative to the surface waters of the lower Ngaruroro River and Clive River described in Schedule 2 of the draft WCO.
5.3 How the reference to “Hydraulically connected groundwater” in Schedule 3 of the draft WCO should be interpreted within clause 11, based on the hydrogeological information.
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6. In my evidence I have used the GGWA area as a specific location to demonstrate the points I am making. Those points also apply to the Hawke’s Bay Winegrowers Association, although their members occur over a more widely distributed area.
EXECUTIVE SUMMARY
7. On the basis of the information I have reviewed and the assessments carried out, I have come to the following conclusions regarding clause 11 and whether there is an issue of concern regarding hydraulically connected groundwater for the draft WCO.
7.1 If Schedule 5 water quality limits are not met, then clause 11 of the draft WCO poses a potentially unrealistic prohibition on many existing discharge activities when their current consents expire. It appears to allow no consideration for the relative significance of a discharge to the quality of the surface waterway and no allowance for the time frame that might be required to upgrade an existing discharge. A land use discharge might in fact be prohibited in circumstances where there is little or no prospect of the discharge entering groundwater that would affect water quality in the Ngaruroro River.
7.2 The GGWA area occurs in a location where the Ngaruroro River loses seepage into the surrounding gravel and groundwater flows in an east or south-easterly direction. Significantly, in respect of what clause 11 is seeking to achieve, groundwater in the GGWA area does not contribute directly to the surface waterways defined in Schedule 2 of the draft WCO.
7.3 Flow gauging surveys, groundwater flow patterns and the presence of a low permeability confining strata overlying the gravel aquifer to the east of Fernhill indicates that there is no obvious area of large, direct inflows of any large groundwater area to the surface waterways defined in Schedule 2.
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7.4 Some land-use activities and discharge to land immediately adjacent to the Schedule 2 waterways could impact on their surface water quality. Therefore, if there is to be a WCO for the lower Ngaruroro River and Clive River, rather than referring to “hydraulically connected groundwater” in Schedule 3 in the context of any clause 11 discharges rule, it would be more appropriate to refer to a riparian buffer adjacent to these rivers where the WCO restrictions could apply. In my opinion such a riparian buffer zone would only need to apply to activities that impact on the Schedule 5 water quality limits and occur within 100 m (or some lesser distance) of flowing water in the Schedule 2 waterways.
POTENTIAL IMPLICATIONS OF CLAUSE 11 FOR THE GGWA
8. The GGWA operate vineyards and wineries in an area of the Heretaunga Plains located between Roys Hill and Fernhill, as show in Figure 1 attached to my evidence. Many of them hold resource consents for the discharge of wastewater to land related to either winery wastewater (from the processing grapes into wine) and/or human wastewater from the buildings used by staff and visitors. The discharge of wastewater to land is a very common practice in rural areas where a reticulated wastewater network is not available. Provided it is well managed it can, in many circumstances, allow for a beneficial re-use of the wastewater and nutrients within the soil to promote plant growth. There will however be occasions during heavy rainfall events where some of the nitrogen in the wastewater leaches down into the underlying groundwater.
9. The GGWA are concerned that if their wastewater discharges to land contribute to any of the waters specified in Schedules 2 or 3 in the draft WCO (which include “hydraulically connected” waters to those waters in Schedule 2) and if these waters exceed the limits in Schedule 5 of the WCO then, when their current consents expire, they may not be able to be renewed because s217(2) of the RMA requires that discharge permits shall not be granted if they would be contrary to any restriction
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or prohibition or any other provisions of the order, once it becomes operative.
10. The discharge of wastewater to land via irrigation is generally considered to be a very beneficial and environmentally friendly way of managing wastewater that is preferable to a direct discharge to surface waters. It allows both the moisture and the nutrient content of the wastewater to be re-used for productive growth of various crops. By managing the application rate and quality of the wastewater to the soil infiltration characteristics the effects of the wastewater on the underlying groundwater and/or nearby waterways can be minimised.
11. Clause 11 provides for no consideration of the size, location, or significance of a discharge that may contribute to the quality of the waterway. So resource consents for even small and relatively insignificant discharges would not be able to be renewed if the limits specified in Schedule 5 are exceeded. This concern is particularly relevant for discharges to land where there is often considerable uncertainty about the migration of contaminants through the subsurface environment and their contribution to surface water quality. Clause 11 would be of concern to anyone who relies on existing discharge consents that are deemed to contribute to the waters in Schedules 2 or 3 (including “hydraulically connected” waters to the waters in Schedule 2).
12. If discharges are deemed to be contributing to poor water quality there are typically improvements that can be made by way of wastewater treatment and/or changes to land application systems to lessen their effect on receiving waterways. However these changes typically require considerable time, cost and planning to implement. Such changes can be implemented via milestone timetables that can be specified in consent conditions. But that option would not be available if the WCO in effect puts a prohibition on the granting of replacement consent applications.
13. In the case of the GGWA, they do not have any direct discharges to surface waterways and so do not directly affect the waters described
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in Schedule 1, 2 or the first part of Schedule 3 (i.e. the tributaries of the Lower Ngaruroro River). However the second part of Schedule 3 refers to “Hydraulically connected groundwater to the water specified in Schedule 2”. It is not specified where this groundwater area is. That uncertainty is of concern to the GGWA, so in the remainder of my evidence I have set out my understanding of how that area of hydraulically connected groundwater should be defined.
HYDROGEOLOGICAL SETTING
Geology 14. Figure 1 (attached to my evidence) shows a geological map of the Heretaunga Plains (Lee, 2014), including the line of major rivers and the location of the GGWA wine growing area. Generally, the Plains represent a fault controlled sedimentary basin, which has been infilled with river and marine sediments and is surrounded by topographically higher limestone and mudstone sediments.
15. Whilst the geological map shows the plains area as single, uniform geological unit, representing Holocene aged strata, there are important variations across the area. East of a line running approximately north east and south west of Flaxmere (shown as a green dashed line on Figure 1) the Holocene aged strata at the ground surface are typically dominated by finer grained silts and sands. These finer grained silts and sands were deposited by the most recent marine transgression across the plains area and form a low permeability wedge that thickens (up to 30 m) towards the coast and provides a confining cap over the more permeable gravel aquifer strata that occurs beneath it and at the ground surface to the west of the green dashed line. These gravelly strata have been deposited by alluvial processes driven by the Ngaruroro River as well as other rivers across the plains. Gravelly strata extend towards the coast beneath the silts and sands and may terminate offshore within Hawke Bay.
16. The gravel deposits extend to a considerable depth beneath the Heretaunga Plains, with an exploratory bore indicating gravel deposits occurring at depths of 400 m below ground level. These gravel deposits
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represent the main water bearing strata used for groundwater abstraction within the Heretaunga Plains. In contrast, the silts and sands that occur at the ground surface to the east do not permit rapid groundwater movement and are generally not used for groundwater abstraction.
Groundwater levels 17. Groundwater levels in the gravelly strata vary. Around the GGWA area, groundwater levels are typically around 3 to 4 m below the ground surface, although there are seasonal variations. Moving east, groundwater levels in the gravelly strata are closer to the ground surface and beyond the inland extent of the low permeability layer of surface silts and sands, groundwater pressures in the deeper strata may be above the ground surface, a situation referred to as flowing artesian groundwater pressures.
18. Above ground pressures occur as a result of the presence the silts and sands that overlie the gravelly strata, particularly across the eastern part of the Heretaunga Plains. The lower permeability silts and sands confine the underlying gravels restricting the vertical movement of groundwater.
19. Seasonal groundwater level variations occur due to groundwater responses to rainfall recharge events, typically higher in winter when little evapotranspiration occurs and lower in summer when more groundwater abstraction occurs. The seasonal change in groundwater levels can be up to 2 m in some locations.
20. In general, groundwater levels decrease towards the coast, and the overall lateral groundwater flow direction is easterly. However, there are local scale variations around groundwater recharge and discharge points, for example around rivers, springs and large scale groundwater abstractions.
Surface water and groundwater interaction 21. Groundwater and surface water are closely linked in some parts of the Heretaunga Plains, and surface water forms the key recharge source to
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the groundwater resource. Groundwater discharge is the key source for a number of spring fed streams that flow across the plains, including the Raupare Stream and the Irongate Stream, shown in Figure 1.
22. Flow gauging along the Ngaruroro River indicates that there is considerable seepage of surface water to groundwater in the reach between Roys Hill and the Fernhill gauging station (shown in Figure 2, attached to my evidence), close to the State Highway 50 bridge across the river (i.e. the reach adjacent to the GGWA area).
23. Downstream of the Fernhill gauging station (i.e. downstream of the GGWA area) and upstream of the boundary of the low permeability confining strata, surface water losses to groundwater are described as variable (Wilding, 2018) and the changes in flow measurements are typically within the margin of error for the gauging measurements. Recent work by HBRC (Wilding, 2018) does not describe flow gains along the Ngaruroro River downstream of Fernhill due to groundwater seepage.
24. Total seepage from the river to groundwater in this area is estimated at around 4.5 m3/s (Wilding, 2018) and forms the major (around 52%) source of recharge to the Heretaunga Plains groundwater system. Other sources of recharge include rainfall recharge across the plains, as well as losses from the Tukituki River.
25. Piezometric contours showing the likely directions of groundwater movement in the aquifer are shown in Figure 2 (attached to my evidence). These contours are based on data from summer 1995 and are representative of lower groundwater levels. Lateral groundwater movement occurs in a direction that is perpendicular to these contours, as shown by the arrows in Figure 2.
26. As noted above, the dominant source of water recharging the aquifer is seepage from the Ngaruroro River. The piezometric contours show that recharge flows south-east and east away from that river and there are a number of discharge points from the aquifer, including (Rakowski, 2018):
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26.1 Discharge to springs that represent the source of the Raupare Stream and the Irongate Stream (42% of total discharges);
26.2 Discharge via groundwater abstraction used for irrigation and public supply, amongst other uses (29% of total discharges);
26.3 Discharge to offshore springs and seeps (29% of total discharges).
27. A summary of the groundwater balance for the Heretaunga Plains is shown in Table 1 (after Rakowski, 2018):
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Table 1: Groundwater balance Source Approximate flow Comment rate (Mm3/year) River seepage 188.6 (71%) Includes seepage to groundwater from Ngaruroro River (138.8 Mm3/year) and seepage from Inflows the Tukituki /Tutaekuri Rivers Land surface 78.5 (29%) recharge Total Inflows 267.1 Spring 111.0 (42%) discharges Groundwater 78.1 (29%) Outflows abstraction Offshore 78 (29%) Estimated discharge Total 267.1 outflows
28. It is important to note that the water budget described above does not identify groundwater discharge to any surface waterways other than the spring-fed streams.
Patterns of groundwater movement beneath the GGWA Area 29. Groundwater beneath the GGWA area is likely to be sourced dominantly from seepage of water leaving the Ngaruroro River, given that the major seepage area from that river is located directly to the north of that area. Based on the groundwater contours for the Heretaunga Plains, that groundwater is expected to flow away from the GGWA area towards the east and south-east.
30. Groundwater moving east and south-east from the GGWA area property is expected to discharge into springs and seeps that form the
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source of the Raupare and Irongate Streams. Groundwater discharge is not expected to occur directly back into the Ngaruroro River or Clive River either because the groundwater flow gradient is away from those rivers or, because in the lower reaches of the plain, the gravel strata is overlain by low permeability silts and sands, which restrict groundwater movement into the river.
HYDRAULICALLY CONNECTED GROUNDWATER
31. Figure 3 (attached to my evidence) shows the location of the surface waterways that are referred to in Schedule 2 and Schedule 3 of the proposed Ngaruroro River WCO.
32. Schedule 2 refers to the mainstem of the Ngaruroro River downstream of the Whanawhana cableway and upstream of the coastal marine area boundary, as well as the Clive River downstream of the confluence with the Raupare Stream.
33. The surface waterways referred to in Schedule 3 includes tributaries to the Ngaruroro River, which are shown in yellow on Figure 3. In addition, Schedule 3 refers to groundwater that is hydraulically connected to the mainstem of the Ngaruroro River and the Clive River (as described in Schedule 2).
34. The term “hydraulically connected groundwater” is not defined in the draft WCO. It typically refers to groundwater areas where there is relatively unimpeded movement of water between a surface waterway and an adjoining groundwater resource. In that regard the Heretaunga Plains west of the green dashed line in Figures 2 and 3 of my evidence is hydraulically connected to the lower Ngaruroro River, but the connection is through river water moving out into the groundwater, not the other way around. Therefore the hydraulic connection in this area does not indicate any risk to the Schedule 2 river water quality from groundwater, which is the intent of clause 11.
35. Hydraulic connectivity is also relevant to management of groundwater abstraction effects on both surface and groundwater allocation, but it
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requires a consideration of the differing degrees of hydraulic connection that occur, as has been done in clause 9(9) of the Water Conservation (Rangitata River) Order 2006 and in Table 5.9.7 of the Tukituki River Catchment section of the HBRC Regional Resource Management Plan. The draft WCO contains no such definition or refinement of the term “Hydraulically connected groundwater” and therefore is not particularly effective at managing groundwater pumping effects on surface water flows.
36. The intent of clause 11 of the draft WCO is to protect surface water quality, relative to the limits in Schedule 5. Therefore I assume the reference to Schedule 3 in clause 11 is intended to define areas where groundwater flows into the surface waterways in Schedule 2 and has the potential to adversely affect the water quality parameters specified in Schedule 5 of the draft WCO.
37. Based on the description of the hydrogeology of the Heretaunga Plains provided in paragraphs 12 to 28 of my evidence, it is unlikely that there is any significant groundwater discharge directly into the mainstem of the lower Ngaruroro River or the Clive River. Certainly, the groundwater underneath the Gimblett Gravels Winegrowers Area does not form part of the groundwater that directly recharges those Schedule 2 waterways to any meaningful extent. It is possible that some groundwater from the northern end of the GGWA area could contribute flow to the confined aquifer that flows beneath the lower Ngaruroro River and the Clive River and that artesian groundwater pressures could contribute some upward seepage through the bed of that river, but that is a long and uncertain flow path and due to the small magnitude and uncertain nature of that flow path it would seem unreasonable for it to be captured by the Schedule 3 definition of hydraulically connected groundwater.
38. It is feasible that land use activities occurring immediately adjacent to the river banks could affect shallow groundwater that might move towards the river under some circumstances, but such a riparian zone would be of a small scale and would not be conservatively wider than 100 m either side of the flowing water channel and probably only 20 m
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in areas where the river is recognised as clearly losing flow into the surrounding groundwater.
39. The tributaries that combine to form the Clive River (including the Irongate and Raupare Streams) can be affected by groundwater discharges, including those from the GGWA area, but those waterways do not form part of the draft WCO, so I presume they are outside the scope of Schedule 3.
40. Therefore, in my opinion, the “hydraulically connected groundwater” referred to in Schedule 3 of the draft water conservation order should not be referred to in clause 11. This is because many areas of the Heretaunga Plains that might be hydraulically connected to the lower Ngaruroro River do not actually contribute any water inflow directly to that river of the Clive River.
41. Instead it would seem reasonable to me if clause 11 referred to surface waters specified in Schedules 1, 2 and 3 and a riparian margin around the surface waterways described in Schedule 2 extending a distance of no more than 100 m from the flowing waterways and around 20 m in areas where the river is recognised as clearly losing flow into the surrounding groundwater.
CONCLUSION
42. In conclusion, if there is to be a Water Conservation Order for the Lower Ngaruroro and Clive Rivers it would be best to remove the reference in clause 11 to the “Hydraulically connected groundwater” component of Schedule 3 and replace it with reference to a riparian buffer adjacent to those Schedule 2 waterways. In my opinion such a buffer would not extend further than 100 metres either side of flowing water and not more than 20 metres in areas where the river is clearly losing flow into groundwater.
Peter Callander 25 January 2019
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REFERENCES
Harper, S. (2015). Groundwater level changes in the Heretaunga and Ruataniwha Basins from 1994 to 2014 (HBRC Report RM15-01-4738). Napier: Hawkes Bay Regional Council. Lee, J. M., Bland, K. J., Townsend, D. B., & Kamp, P. J. (2011). Geology of the Hawke's Bay Area. Institute of Geological and Nuclear Sciences 1:250 000 geological map sheet 8. 1 sheet + 93 p. Lower Hutt, New Zealand: GNS Science. Rakowski, P., & Knowling, M. (2018). Heretaunga Aquifer Groundwater Model Development Report. HBRC Report RM18-14-4997. Napier: Hawkes Bay Regional Council. Wilding, T. (June 2018). Heretaunga Spring: Gains and losses of stream flow to groundwater on the Heretaunga Plains. HBRC Report RM18-13 - 4996. Napier: Hawkes Bay Regional Council.