1 BEFORE THE TASMAN DISTRICT COUNCIL
IN THE MATTER of the Resource Management Act AND
IN THE MATTER of an application by the TASMAN DISTRICT COUNCIL (ENGINEERING DEPARTMENT) for resource consents for aerial and ground based herbicide discharge to land, water, and air, for the purposes of controlling woody weed growth within river flood channels within Tasman District.
STATEMENT OF EVIDENCE OF RHYS FRANCOIS GEORGE BARRIER Dated 18 November 2015
INTRODUCTION
1. My full name is Rhys Francois George Barrier.
2. My evidence is given on behalf of Fish & Game NZ (Nelson/Marlborough Region) in support of my submission in opposition in relation to an application for resource consents for aerial and ground based herbicide discharge to land, water, and air, for the purposes of controlling woody weed growth within river flood channels within Tasman District.
Qualifications and Experience
3. I hold the degrees of Bachelor of Science, and Master of Science (Hons) in Freshwater Ecology from the University of Waikato. I am currently the regional manager for Fish & Game New Zealand within the Nelson/Marlborough Region.
4. I have been involved in the Resource Management, aquatic monitoring, and stream
management areas for the last 20 years. Prior to my appointment as the regional Fish & Game manager for Nelson Marlborough Region, I held the role of Fish & Game Field Officer within this region for over 10 years. Prior to this I worked for the Department of Conservation – five years as a freshwater technical support officer, and 2 years writing native freshwater fish recovery plans to guide the Departments freshwater work including its Resource management advocacy activities for threatened fish species. My earliest employment included a contract with the Waikato Regional Council to assess mitigation options for their flood control scheme on the Waihou River following extensive willow removal, and I also worked as a freshwater fisheries research technician for NIWA in Hamilton for several years.
5. In my 10 year role as a Fish & Game Field Officer within the Nelson/Marlborough Region I have walked over 100 kilometres of riverbed undertaking routine angler compliance work, habitat
2 assessments, or angling. I have also participated in over 200 drift dives within the region’s rivers, each in the order of 1-2 km of stream or river length, thus have personally snorkelled a collective total of well over 200 kilometres of Tasman’s riverbeds, directly observing preferred brown trout habitat preferences (where trout like to live), in rivers such as the Motueka that are dived every year by Fish & Game. I have also witnessed first-hand the effects of severe heat stress on the temperature sensitive Motueka trout fishery, with a number of dead juvenile eels and dead adult brown trout observed several times over the last 10 years.
6. In my time as a Fish & Game Field Officer (and previously as a DOC Freshwater technical support officer), I have observed first hand numerous examples of changes in salmonid habitat quality as a result of willow management. Some of these effects are positive, and many are negative. I consider I have an intimate knowledge of both the immediate site specific and cumulative long term effects of willow removal through herbicide application on the salmonid fishery habitat within this region that I am now charged with managing on behalf of many thousands of fishing licence holders whom fish in Tasman’s Rivers annually.
7. I have resided within the Nelson/Tasman area for over 20 years, and know the region well.
My Role
8. My role with regard to this application is to assess the likely impact of this 15 year herbicide discharge consent application in relation to whether it provides for sustainable river management in terms of protection and enhancement of adult brown habitat within the regions rivers on behalf of licenced of anglers, as directed by objectives and policies within the Nels on Marlborough Sports Fish & Game management plan, a statutory legal document signed off by the Minister of Conservation.
Scope of Evidence 9. My evidence:
a) Provides brief historical and present day observations on river management, followed by
background information in relation to the values of Tasman’s trout fisheries, declining angler use of some of these fisheries, and cumulative impacts of flood control work including willow removal on selected trout fisheries.
b) Describes specific areas of concern to Fish & Game within the consent application (as submitted on) referenced with relevant references, and two regional case studies.
c) Comments briefly on matters raised by the reporting officers within their Section 42A report.
d) Comments briefly on aspects of the applicant’s statements of evidence.
e) Discusses the Fish & Game relief sought, including suggested consent conditions that would address concerns with this application.
f) Discusses consent term, followed by a list of references.
3 HISTORY
10. Over time Fish & Game have observed the cumulative impacts of reduced channel sinuosity, stability, and cross-sectional variation resulting from channel realignment and constraint facilitated by a shift from historic use of predominantly managed tree willow within wider river fairways as the primary tool for erosion protection, to the modern day preference of the use of hard rock solutions, particularly regularly sprayed rock riprap, within much more constrained river fairways. While many of these activities are the subject of a previous application by Tasman District Council (35 year global consent application for river works), they are inter- related to this herbicide application as noted in paragraph 9.123 of the officers report for this application. Approaches such as this to river management have significant adverse effects on the natural character of river ecosystems and their processes. On a region wide basis results of this habitat destruction on the trout population are impossible to quantify, however there is a wide array of literature that point to the likely cumulative effects of this approach to river management on brown trout populations, supported by regional examples. Much of this has been addressed in previous evidence relating to the prior global river works consent application for activities other than spraying, so accordingly this evidence will focus just on salmonid habitat and water quality impacts of willow removal through spraying.
11. Fish & Game’s obligations for maintaining or improving adult salmonid habitat, and Tasman District Council River Services goals of flood protection and erosion control, are not mutually exclusive. If overseas examples are examined such as forward-thinking river control programs in parts of the United States, the river control agency can save a lot of money, whilst at the same time improving the natural character of rivers, habitat health and where relevant to the river type habitat diversity, along with ecosystem health and processes including fisheries habitat. What is required however is an approach to river management that takes into account the natural form and function of rivers and their ecosystems, and a river management authority which works in partnership with other agencies such as Fish & Game, the Department of Conservation and Iwi.
This is the outcome that needs to occur within Tasman’s Rivers if all agencies with an interest in river management are to move forward effectively together to try and meet the challenge and cost of climate change and the severe flood events it will bring to our region.
BACKGROUND
12. Fish & Game Nelson-Marlborough is the statutory manager of sports fish and game birds throughout the region. The Fish and Game Council is responsible for the protection and
management of populations of game birds and sports fish in the recreational interests of hunters and anglers. This includes, pursuant to Section 26 of the Conservation Act 1987, to:
“manage, maintain and enhance the sports fish and game resource in the recreational interests of anglers and hunters”;
“assess and monitor the condition and trend of ecosystems as habitats for sports fish”;
“advocate the interests of the Council, including its interests in habitats;” and
“represent the interests and aspirations of anglers and hunters in the statutory planning process.”
13. The Resource Management Act 1991 also guides Fish & Game involvement in matters such as this, particularly:
section 5 which states that the purpose of the RMA is to ensure the sustainable management of natural resources including freshwater, and requires that the life supporting capacity of
freshwater be safeguarded
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section 6(a) that obligates the committee to recognise and provide for as a matter of national importance the preservation of the natural character of rivers and their margins; and
section 7(h) that details matters for regard specifically relating to the protection of the habitat of trout.
14. The National Policy Statement for Freshwater Management which sets in Objective A1 that the life supporting capacity and ecosystem processes of freshwater be safeguarded, and which recognises the value of natural form and character.
15. A Water Conservation Order has also been in force on the Buller River since 2001, and the Motueka River since 2004. Water Conservation Orders are the highest form of legal protection available for rivers within New Zealand and are equivalent to a National Park on a river in terms of status. Both these Water Conservation Orders provide a clause allowing for river control maintenance work by Council pursuant to the Soil Conservation and Rivers Control Act 1941, however this work must be undertaken within the context of the order (not materially altering
‘form and function’ of specified waters), and within the context of recent amendments to this 1941 Act including:
Section 10A of the Soil Conservation and Rivers Control Act (1941) which states that
“nothing in this Act shall derogate from the provisions of Section 176 to 182 of the Harbours Act (1950) or the Resource Management Act (1991) – as listed in the Eight Schedule (s 362) of the RMA (1991). This ensures that the adverse effects of fulfilling these responsibilities are required to be avoided, remedied or mitigated.
16. Fish & Game concerns regarding river spraying works relate primarily to x and y-rated sections of recognised trout fisheries or spawning streams within the Tasman region. Generally, due to the different river rating classification, large scale river control works such as extensive willow spraying, are not undertaken anywhere near as extensively within z-rated rivers, as landowners are required to pay for at least 50% of the cost of any such spraying, which in effect means a lot less spraying work gets done in river catchments with a z-rating classification. The outcome of this is that z-rated river sections tend to often have significantly better trout habitat, as illustrated later within this evidence in relation to the Motupiko trout fishery.
17. The Motueka Water Conservation Order aims to provide protection for the Brown trout fishery in the Wangapeka and the Motueka River. While the upper section of Motueka River above the Wangapeka confluence has limited protection from the 2004 Water Conservation Order (as this part of the fishery never met a nationally outstanding threshold), it is a vital link between
recognised spawning streams (Blue Glen, Rainy, Motupiko and Tadmor) and the outstanding brown trout fishery in the Motueka River downstream of the Wangapeka confluence and the Wangapeka itself.
18. The Motueka catchment used to be the Nelson/Marlborough regions number one fishery in terms of angler usage, and was once rated top equal with the Mataura in Southland as one of New Zealand’s best brown trout fisheries. However despite being protected by a Water
Conservation Order since 2004, angler use data (measured by a NIWA National Angler Survey undertaken every 5-7 years), has halved within the Motueka catchment during the last two decades, dropping from 12130 (+1380) in 1994/95, to 6190 (+590) in 2007/2008 (Unwin 2009).
The Wairau River in Marlborough now surpasses the Motueka as the region’s most well used fishery. The Motueka use decline has even been significantly higher than angler use rate declines within the Buller Catchment which is very surprising given the massive direct impact of
5 Didymo on the Upper Buller catchment fishery. By contrast, Didymo within the Motueka never approaches nuisance levels and is generally very hard to even detect.
19. Reasons for this large decline in angler use rates of the Motueka catchment, are basically that fish numbers have never got back to the high population levels they were two decades ago when the Motueka was regarded internationally as a premier brown trout fishing destination.
Fish & Game monitor adult trout populations within many of Tasman’s rivers by floating down selected monitoring sites in formation and counting fish observed (termed drift diving). The drift diving dataset that Fish & Game hold for the Motueka at Glenrae (above the Wangapeka confluence), shows the fishery at this location to have never recovered back to its highs of the late 80’s - mid 90’s.
20. Drift diving data for the Motupiko at Quinney’s Bush site (y-rated) shows an even worse decline with no sign of population recovery on the horizon for the fishery at this location either.
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00
Biomass (g/m2)
Abundance (kg/km)
Motueka River Weighted Abundance and Biomass Changes Glen Rae site
Abundance (kg/km)
0.00 0.50 1.00 1.50 2.00 2.50 3.00
0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00
Biomass (g/m2)
Abundance (kg/km)
Date Drift Dived
Motupiko River Weighted Abundance and Biomass Changes above Quinney's Bush site
Abundance (kg/km)
Note: 1989 & 1996 dive lengths 300m shorter in length
6 21. Drift diving data for the z-rated section of the Motupiko at Newports consists only of one dive in
1989, and a subsequent dive in 2015, which is not enough data to draw reliable trend information from. Trout abundance of 8.31 kg/km was recorded at Newports in 2015 as opposed to the 1989 Newports dive when trout abundance of 8.43 kg/km was recorded,
although the 1989 site was 300m shorter that the 2015 site. If adjusted for this length difference, a 1989 dive could have recorded an estimated abundance of around 11.21 kg/km, so a small decline may have occurred, but this decline would be nowhere near as significant as the lower Quinney’s Bush (y-rated site) decline, which has been catastrophic, and remains depressed.
22. It is my view that while several large flood events initiated these declines, the ongoing disturbance and resultant loss of habitat at these sites as a result of river control works (including for example Crack willow removal and subsequent re-spraying within the y-rated section of the Motupiko since 1990 designed to ‘homogenise’ and straighten channel
morphology and improve flood capacity), have contributed to a lack of fishery recovery. I hold this view due to the observed cumulative effects of decades of river control works that have not been required to effectively consider the impact and therefore potential mitigation, of a river control agencies response to floods on adult brown trout habitat, as evidenced by drift diving information discussed above, and the pool survey outlined later within the Motupiko River Case Study.
23. This Motupiko case study was presented as part of my evidence in relation to the preceding Global River works consent application, but is included here again, given the inter-related nature of issues between these two consent applications, as mentioned in the officer’s report
(paragraph 9.123). For example, it was Crack willow removal within the Motupiko that led to the initial pool/loss fishery decline following flooding in the view of Fish & Game, and the subsequent spraying out of most Crack willow regrowth (combined with historic use of rock riprap and shrub willow species only), has meant adequate pool reformation/fishery recovery has not been able to occur to date.
SPECIFIC AREAS OF CONCERN WITHIN THE GLOBAL RIVER SPRAYING CONSENT APPLICATION
24. Water temperature: The officer’s report for the preceding global river works hearing (parts of which relate to this present consent application), noted the following: “River works have the potential to increase the temperature of a river. This can occur by reducing shading with the removal of riparian vegetation, increasing solar gain with a wider/shallower channel and
increasing the thermal mass of rockwork.” This current global river spraying consent application includes the activity of ground based spraying of riparian willow (proposed 5 m riparian buffer only applies to aerial herbicide application), including willow growing within rock riprap. Removal of riparian willow, including spraying out willow regrowth, is an issue of concern to Fish & Game which remains unresolved from the previous global consent hearing.
25. I contend that the issue of temperature elevation occurring as a result of river engineering practices has now already occurred within the lower Motupiko, and the Upper Motueka (Gibbs road – Glenrae area) rivers. Extensive integrated catchment management research undertaken by the Cawthron research Institute on the Motueka catchment led to the discovery that this once world class brown trout fishery is actually on a ‘knife edge’ from a summer water temperature
7 perspective. Every few years Fish & Game receives complaints, and observe dead or dying juvenile eels and adult brown trout in parts of the Motueka River. This usually occurs after a number of consecutive days of hot night time temperatures (heat-wave type conditions), meaning the water temperatures do not drop sufficiently at night to allow respite for fish.
26. Last summer a Fish & Game data-logger installed at the Tapawera Bridge, showed daytime river temperatures during a prolonged low flow period to be reaching 24 oC which can be lethal for brown trout. The relative effects of elevated stream temperatures verses loss of stream morphology are difficult to separate, but both play an important role in salmonid fishery health.
Shading from mature tree willows, along with the ability of these trees to form flood flow resistance, leads to four beneficial outcomes for adult brown trout habitat. These benefits are:
shading of rock riprap/water column assists in retaining cool water temperatures vital for salmonid survival; mature tree resistance to flood flows assists with deep scour pool formation which provides adult trout habitat plus also assists with retention of cool waters
(depth=coolness, plus can intercept groundwater inflows); mature trees provide essential overhead trout cover for adult salmonids; and mature trees provide large amounts of trout food such as willow grubs/cicadas.
27. Of concern, data-loggers deployed last summer (data available upon request) within the lower Motupiko at the bottom of the heavily engineered y-rated river section where all mature tree willow has been effectively removed (below the Quinney’s Bush drift dive site), show that on a number of occasions peak daily water temperature exceeded 27 degrees, and daily averages were well over 22 oC. This is approaching lethal water temperature for brown trout (Hay 2006), and trout deaths have been reported in New Zealand rivers when water temperatures have equalled or exceeded 26 oC (Jowett 1997). When corresponding data-logger information from the z-rated section of the Motupiko at Newports (start of foot surveys above y-rated heavily engineered zone), over the same period is compared, the results are startling. For example, Jan 29th 2015, Motupiko below Quinneys recorded a daily maximum water temperature of 27.7 oC, and a daily average water temperature of 22.5 oC. Temperature data-logger information on the same day within the Motupiko at Newports recorded a daily maximum water temperature of 22.5
oC, and a daily average of 20.6 oC. After reviewing this water temperature data-logger
information it is my opinion that the temperature regime within the lower y-rated Motupiko River section during the hottest part of summer is now currently likely to be lethal to brown trout that do not have thermal refuge habitat available. Deep pools are generally required to either intercept groundwater inflow, or provide a deeper reservoir of cool water that is less susceptible to daily temperature spikes, in order to provide this thermal refuge habitat for their survival.
28. Increasing deep water pools within a river system through targeted engineering practices, along with increasing shading of both water and installed rock protection work, can therefore
effectively mitigate both instream cover loss created by river morphology deterioration, and the peak summer water temperature stresses this can also result in (wide shallow unshaded wetted channels, combined with excessive hard rock engineering). An example of this mitigation is shown below in the lower Appleby River below. This deep pool has formed through a
combination of an existing rock riprap wall in a river system large enough to create depth around the riprap, combined with extensive tree willow regrowth being allowed to occur within the riprap instead of being routinely sprayed out as occurs currently within some other Tasman River sites (e.g. lower Motueka). This combination has allowed a deep scour pool to form at this site due to the effect of flood flows on riprap combined with mature overhanging tree willow species leading to high-flow resistance and thus additional scour turbulence during flood events. When I drift dived this pool with other Fish & Game staff on March 2nd 2015, I observed a pool some 4-5
8 metres deep. When I dived down towards the bottom to count fish, I felt an estimated 8-10 oC drop in river water temperature. Presumably the river morphology at this point was deep enough to intercept cool groundwater inflow and this feature (thermal refuge) combined with extensive overhead shade and cover afforded by tree willow that has been allowed to regrow within the rock riprap, meant a school of 14 large well-conditioned adult brown trout were present on the bottom of this pool within the area indicated.
29. Simply allowing tree willow (not shrub willow) to regrow through existing rock riprap structures within the larger river systems such as the Waimea, Motueka, and Takaka, could therefore substantially mitigate the adverse effects of these structures on salmonid fishery’s, both from a morphology and temperature perspective. The officer’s report for the previous global river works consent supported this approach, where it was noted that ‘in larger rivers one way of mitigating the heat-sink effect of rock riprap is simply to allow willow regrowth, which will provide some trout cover and heat sink mitigation’. This is a matter that remains outstanding from the previous consent and it was indicated to Fish & Game post hearing that this aspect was better resolved through this global herbicide consent application given most willow regrowth through riprap is controlled with ground based spraying activity. Accordingly a consent condition that would potentially meet our concerns with regard to willow spraying amongst rock riprap is discussed within the relief sought section at the end of this evidence.
30. Allowing willow regrowth through rock riprap was not accepted by the applicant following negotiations over the previous global consent application for river management activities other than herbicide application, and in the end the matter was deferred to be dealt with through this herbicide consent, given spraying is the method used to prevent willow regrowth. There was a suggestion by the applicant during the previous global consent hearing application, that allowing willow to grow amongst rock riprap could theoretically prevent riprap ‘self-healing’ after toe scour, due to tree roots holding rock work up. Given the normal size of present day rock riprap (huge), and the fact I have yet to observe this effect within any Tasman River after diving over 200 kilometres of waterways, I find this reasoning hard to accept. There are also dozens of examples of mature tree willow growing amongst older (smaller) riprap that I have observed within our region (one example is illustrated above earlier within this evidence), that are causing no issues to riprap integrity, but are completely mitigating most of the negative instream habitat impacts of the riprap. Additionally, it is also common practice in other countries to actually interplant rock riprap with willow (Minnesota Department of Natural Resources 2015).
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31. Willow removal: While most mature tree willow within this region has been mechanical, technically mature riparian tree willow can be removed through ground based basal spraying or other techniques that would be provided for by this resource consent. Effects of mechanical willow removal remain unresolved from the prior global river works consent, and remain the same for chemical removal, in terms of habitat and water temperature issues.
32. Tree willow removal (predominantly mature Crack willow) has had three major effects within Tasman trout fisheries. The first and most obvious effect is the site specific effect of loss of adult brown trout cover and overhead terrestrial food input. These effects can lead to localised fishery collapse within smaller rivers as is discussed within the Riwaka case study, and can also lead to loss of pool habitat in smaller systems as is discussed within the Motupiko case study.
The second effect is water temperature. This effect is more cumulative in nature particularly within trout fisheries such as the Motueka and tributaries such as the Motupiko that are already on a knife edge from a high summer water temperature perspective. The third and most insidious impact of tree willow removal is the loss of bank stability leading to a subsequent justification for hard rock protection to arrest the erosion created by the original and subsequent ongoing tree willow removal through mechanical or chemical means. This in turn also
exacerbates the initial impact on water temperature caused by shading removal, due to the heat sink effects of hard rock protection as more and more rock protection is required following willow removal.
33. While there are cases for targeted management, or if necessary removal, of mature crack willow within smaller streams due to channel capacity constraints (for example the Dovedale), removal of extensive areas of tree willow (usually Crack willow) can and does cause serious long term impacts on smaller waterways if the shading and stability functions are not adequately replaced through use of appropriate low branching tree willow clones (e.g. ‘Moutere’ clone) or where appropriate natives. Natives generally only work on very small river systems within Tasman, or straight sections of intermediate rivers and such replacement work should be done very
gradually rather than in extensive sections.
34. In relation to mechanical willow removal, the officer’s report for the previous hearing recommended consent conditions to ensure only a minimum amount of vegetation was
mechanically cleared to achieve the required river works and limits were proposed on the length of works, limiting the works to relatively short sections of river. Suggested condition 76C stated
“Any willow clearance shall not exceed a continuous 2.5 kilometre reach within any 5km reach in any 12 month period”. This distance (50% clearance), had the potential to cause considerable instream temperature elevation and was considered far too large to be adequate to address our concerns, particularly given our experience over the last 10 years with Tasman District Council’s very misguided policy on Crack Willow eradication within all the regions waterways. This policy led to a massive increase in the requirement for hard rock protection in many sites where Crack willow removal was undertaken, with examples observed within the Upper Motueka,
Wangapeka, lower Motueka, Riwaka and Wai-iti to name a few. Indeed the field data recently collected from the Motupiko indicates that Crack willow removal from the mid-lower Motupiko and subsequent pool loss has led to fishery collapse within this area due to pool loss and elevated summer water temperatures. More appropriate conditions to alleviate our concerns were discussed with the applicant during the global river works hearing but no agreement was reached.
10 35. Two consent conditions that had potential to address our concerns in relation to riparian willow
removal through mechanical or chemical means were suggested to the applicant after the previous river works activity consent hearing. These remain un-agreed, but as noted at the time could potentially address Fish & Game concerns in relation to this global river spraying consent application also. They are relevant to this application as chemical means are often used for willow control or removal, and the 5 m buffer for aerial spraying buffer does not apply to ground based spraying. These conditions are presented within relief sought at the end of this evidence.
REGIONAL EXAMPLES TO ILLUSTRATE CONCERNS Case study 1: Riwaka trout fishery
36. Once this fishery had the highest trout biomass per square metre of any trout fishery within NZ, and was listed by MAF Fisheries at the time of the ‘100 rivers survey’ initiated by Ian Jowett to be a “willow dependent trout fishery” (Jowett 1990). In line with angler use rates for most of the rest of the Motueka catchment (apart from the Wangapeka), angler use statistics for the Riwaka River show a sharp decline with angler use dropping from 620 (+220) in 1994/95, to 320 (+110) in 2007/2008 (Unwin 2009).
37. Historically the lower Riwaka provided high numbers of adult brown trout, which would have augmented the entire Riwaka fishery given the behaviour of brown trout in relation to extensive seasonal movements within river catchments. Anecdotal feed-back from anglers whom
regularly fish this river consistently state that the fishery collapsed following extensive tree willow removal below the State Highway. Fish & Game have had ongoing complaints from numerous anglers over the last decade about the parlous state of this once great fishery. This suggested collapse aligns with various overseas literature references that confirm adult brown trout are strongly orientated around structural instream cover (Binns 1979, Jowett 1990). Unfortunately Fish & Game drift dive monitoring sites do not cover this section of the river so we have no site specific pre/post willow removal fish counts for this section of the Riwaka. Field data recently collected from the Motupiko (described within Motupiko case study below), illustrates
convincingly what loss of pool willow cover can do to a brown trout fishery however.
Present day lower Riwaka – devoid of overhead willow cover (once a stunning fishery).
38. The entire lower Riwaka River is now a fishery almost completely devoid of all willow except a few weeping willow poles that TDC River Services staff allowed Fish & Game to plant at the top
11 of rock riprap walls. Given the height these poles were required to be planted above the water, it will be years before they provide any overhead cover benefits, if at all, to this fishery. Council River Services staff will not allow any wild willow regrowth within this area of the river due to stated channel capacity constraint issues with inadequate stop banks (designed for a 1:20 year return flood period only). A consent condition specific to the Riwaka that stipulated only re- growing willow over 4 metres high, or with a basal stem diameter > 15cm, be sprayed, could meet Fish & Games concerns about cover loss within this system, and willows of this size would not pose a huge channel capacity constraint in our view. The present blitzing of all live willow within this zone effectively means the entire lower channel will eventually all need to be rock lined, as not only is there no cover present, there is also no bank holding willow, meaning remaining banks without rock lining are very vulnerable to increased flood scour impacts from ever increasing rock protection works that are now being constructed within this fishery.
39. A brief visit I undertook on 22/09/15, showed the concern expressed above to be valid – the latest round of riprap is now even being installed on the inside of river bends within low scour zones, and most new rock riprap was either at the end of existing hard protection work, or downstream on the opposite bank.
It would not be hard for me to walk this river and point out where next year’s riprap will now be required. The Council has agreed to Fish & Game planting flax or toitoi amongst existing riprap, and weeping willows at the top of riprap wall however it is very unlikely this will even come close to providing the amount of overhead fish cover that once existed in this part of the fishery. A toitoi planted by Fish & Game can be seen in the above picture upon close examination!
40. To properly mitigate the present and likely future increase in hard rock protection in this fishery a consent condition that stated willows will not be sprayed within the lower Riwaka unless they are either greater than 4 metres in height, or greater than 15cm basal stem diameter was suggested within the relief sought section for the previous global river works consent application. During subsequent negotiations with the applicant, it was noted by the applicant that the activity of spraying out willow regrowth was more appropriately dealt with through this present global resource consent for rivers spraying however.
41. Allowing willow to reach this size within the lower Riwaka before selective spray removal means the salmonid fishery effect of excessive present and likely future riprap levels could be partially mitigated which will go some way towards restoring the past collapse of this fishery due to complete willow cover removal. There are currently still pools in this lower site for adult
12 salmonids, what is missing is the presence of overhead cover. A maximum size restriction for live wild willow such as the one suggested, would also mean willows would be killed before they reached a size sufficient to cause any significant channel capacity issues in a flood – any willow less than 4 metres tall will generally bend over in a flood and not create significant obstruction to flood flows. Such a policy may even slow down the eventual requirement to rock 100% of the lower channel below the State Highway due to the high percentage of hard rock protection that already exists here now.
Case study 2: Motupiko trout fishery
42. In line with angler use rates for most of the rest of the Motueka catchment (apart from the Wangapeka), Angler use statistics for the Motupiko show a sharp decline with angler use dropping from 380 (+150) in 1994/95, to 70 (+40) in 2007/2008.
43. The Motupiko River near Quinney’s Bush has a Fish & Game drift dive monitoring site present.
Unfortunately the site has not been dived frequently enough to pick up exact dates of the decline of this once great small fishery at this location, but the limited data we do have is illuminating.
The earliest dive we have of the Quinneys Bush site is February 1989 (when the entire Motueka catchment was in superb condition fishery wise), and during that dive 11 large, 87 medium, and 89 small fish were counted over a river dive distance of 2.5 km. The last time this Quinney’s Bush site was dived in October 2015, a total of 7 large, 1 medium, and 3 small fish were all that was counted over a distance of 2.8 km (see drift diving graph earlier in this evidence). Staff also commented during this last dive that “two adult trout were located within pools formed by scour around recent rock groynes instalments” (Fish & Game unpublished drift dive monitoring data).
The fact that two adult fish were located within pools formed by recent rock groynes gives me confidence that future erosion control works within this catchment, if undertaken in a manner sympathetic to adult brown trout habitat requirements, have the potential to assist in restoring this once excellent trout fishery. Any such restoration activity would need to include inter- planting of tree willow between rock groynes and not spraying it out during routine spray maintenance activities.
44. Fish & Game staff undertook a foot survey of the Motupiko riverbed at several locations including the Quinney’s Bush drift dive monitoring site on 29th September 2015, to record the number of pools with good, limited, or no overheard trout cover present, size of pools, what had formed the pool (pool origin), and the presence of Crack or other large mature tree willow species at each pool. Pools were defined and recorded as areas of wetted channel over 1.2 metres deep, as this depth has been defined by the Cawthron Institute in relation to earlier Motupiko salmonid research work, as necessary to sustain adult brown trout within this system over the summer months (Young 2010). The locations this was done included the 4.68 km section of the Motupiko river immediately above the Korere bridge (z-rated so little historic engineering intervention), a 5.94 km section of the Motupiko River immediately below Korere bridge (y-rated, so extensive engineering intervention including historic Crack willow removal), and a 5.19 km section immediately below where the middle survey section stopped, to
Quinney’s Bush camp (also y-rated/extensively engineered and all Crack willow removed).
13 Top (green), Middle (yellow), and bottom (red) pool foot survey transects done in 1 day.
45. Results in the following table show that site 1 above Korere (minimal engineering
intervention/mature crack willow trees remaining) had many more and significantly larger pools compared to the site below Korere and the site at Quinney’s Bush (both heavily engineered / limited tree willow remaining).
46. As can be seen from results of this brief pool survey contained within the table below, the
average size of pools within the z-rated zone is at least twice that of pools within both the y-rated engineered zones. The z-rated zone (site 1) also has 1 pool per 156 metres, compared to 1 pool per 297 metres within site 2 (y-rated), and 1 pool per 247 metres within site 3 (y-rated).
47. As well as having a significantly higher number and average size of pools, site 1 also had ‘good’
brown trout cover at 83% of pools, as opposed to good cover only being present at 45% and 14% of the bottom two engineered sites. Trout cover was assessed by Fish & Game staff who are experienced anglers and drift divers and have a good understanding of the cover
requirements of adult brown trout. The same staff member assessed the top site (1),and then the bottom site (3), so the same objective assessment was applied to both these sites for fish cover with a staggering 83% - 14% difference in the two sites. I believe this is a direct
consequence of historic and present day engineering practices within this system (including replacement of crack willow with shrub willow and ongoing crack willow regrowth spraying) and demonstrates why our drift diving information at Quinney’s Bush shows no sign of trout fishery recovery at this location, whereas the Newport’s site has not had a major fishery collapse over the same period.
Pool Area (m2) Origin Cover (Zero/Limited/Good) Mature tree willow present Trout Present
SITE 1 1 96 B Good (>2m) 0 1
4.68km r.bed 2 24 W Good 1
3 50 W Good 1
4 18 W Good 1
5 36 B Good (>2m) 0
6 10 W Good 2
7 20 W/BR Good 1
8 24 B/W Good 2 1
9 45 B/W Good (>2m) 0 2
10 18 W Good 3 1
11 52 B/W Good (>2m) 1 1
12 42 B/W Good 2
14
13 45 B/W Good 1
14 10 B/W Good 1
15 21 W Good 2 1
16 15 RR Zero 0
17 27 B/W/G Good 1
18 30 B Good 1
19 28 W Good (>2m) 1 1
20 21 W Good 3
21 40 G Good (>2m) 0
22 10 B Zero 0 4
23 12 B Good 1 1
24 15 G Zero 0
25 32 W Good 3
26 36 W Good 1
27 33 B/W Good 1
28 10 G Zero 0
29 33 RR Good 2
30 8 RR Zero 0
Average 28.7 83% good adult BT cover MatureTree willow at 70% of pools total = 13
SITE 2 1 3 G Zero 1
5.94km r.bed 2 10 W Good 3
3 5 B Zero 0
4 4 B Limited 0
5 10 G Limited 0
6 3 G Limited 0
7 8 B/W Good 1
8 10 RR/W Zero 0
9 12 RR/W Good 0
10 5 CSW Good 0 1
11 30 CSW Good 0
12 15 G/W Limited 5
13 20 W Good 1
14 15 B Limited 0
15 25 G Good 0 1
16 8 RR Limited 0
17 4 G Zero 0
18 4 G Zero 0
19 6 CSW Good 1
20 25 CSW Good 0 1
Average 11.1 45% good adult BT cover MatureTree willow at 30% of pools total =3
SITE 3 1 2 W Good 1 1
5.19km r.bed 2 4 RR Limited
3 4 B/W Limited 2
4 2 CSW Limited
5 5 B/W Limited
6 10 B/W Limited 1
7 60 G Zero
8 18 W Limited
9 3 G Zero
10 43 B/W Good (>2m) 1
11 3 CSW Zero Key
12 2 G Zero B Bank
13 4 G Zero W Willow
14 33 G Zero G Groyne
15 28 B/W Good (>2m) RR Riprap
16 4 G Zero BR Bedrock
17 14 G Zero CSW Collapsed shrub willow
18 8 CSW Limited 1
19 32 CSW Limited
20 8 B/W Zero
21 8 W Limited
Average 14.0476 14% good adult BT cover MatureTree willow at 5% of pools Total = 6
15 48. In my expert opinion as a salmonid fisheries manager, the lower Motupiko will never recover as
a brown trout fishery until such time as more pools with adequate tree willow cover are created as currently still exist in the upper part of this fishery above Korere, where engineering
intervention has been light due to the surrounding land rating status. It is also my opinion that based on the predominant rock riprap and shrub willow character of the y-rated part of this river, combined with a complete lack of mature tree willows such as Crack willow (eradicated
previously by River Services – see page 33 of draft EMP supplied by Giles Griffiths with their global river works consent application), that it is highly unlikely that more pools will ever form within this reach over time, unless future river control works that are designed to encourage pool reformation, are implemented. Use of rock spurs or groynes instead of riprap, with tree willow stake plantings between rock groynes at waterline level could achieve this. Allowing crack or other tree willow species to regrow through existing riprap would also help. Shading from tree willow in combination with an increase in deep water pools would assist to try and mitigate the high instream summer temperature issues that now exist within this fishery.
SECTION 42A OFFICERS REPORT
49. The officer’s report concludes in paragraph 9.99 that given this consent is only for the spraying of river beaches and islands and not vegetation along banks for the two rivers, there will therefore be limited adverse effects on factors influencing trout habitat by the removal of vegetation along banks for the two rivers. This conclusion has presumably been arrived at due to the suggested 5 m buffer strip applying to aerial spraying. No such buffer strip currently applies to ground based herbicide discharge however, which is the usual technique used to eradicate wilding willow within rock riprap. During the previous consent hearing for river work activities other than spraying, a condition allowing willow regrowth amongst riprap was sought to try and mitigate thermal heat sink issues created by these structures within trout fisheries.
During subsequent negotiations with the applicant however, it was suggested that willow regrowth amongst rock riprap was an issue best tackled within the bounds of this resource consent for herbicide discharge. This overlap with residual habitat concern issues from the previous consent is alluded to within the officer’s report in paragraphs 9.123, and 9.141(second bullet point).
50. Accordingly, there are habitat issues of concern that remain outstanding with this herbicide consent, both in relation to removal of willow regrowth amongst riprap, but also potential removal of mature riparian willow through ground based herbicide discharge (e.g. basal spraying). Two unaccepted draft consent conditions were suggested during negotiations with the applicant over the last consent application for river works. These draft consent conditions are again suggested within this body of evidence under the relief sought section at the end of this evidence.
STATEMENTS OF EVIDENCE PROVIDED BY THE APPLICANT
Giles Griffiths
51. Fish and Game support the work of Mr Griffiths which focusses on soft engineering approaches to river management and seeks to use willow species or natives (within smaller systems) for
16 river control plantings that are more conducive to good salmonid habitat. In effect this means phasing out the use of shrub willow, and switching instead to appropriate tree willow clones, as a frontline river defence species within our rivers, for example in relation to future plantings within the Motupiko. Where these plantings result in pool reformation, it will also be critical that they are not routinely ‘layered’ or sprayed out within these locations in future as it is essential they remain as mature standing trees to try and replicate the instream habitat benefits of historically removed Crack willow We would also like to see the use of a lot more planted tree willow to mitigate any new rock protection work within rivers where this is now required, along with allowing willow to regrow amongst existing rock riprap.
52. In his evidence (page 4, para. 16) Mr Griffiths notes the example of the Mararoa River in
Southland, where a community river restoration project was undertaken from 2000-2011, which included Crack Willow removal, and a widening of the river Fairway. This project is a good example of an agreed multi-stakeholder river management project, and a process Fish & Game would like to see start to occur with river management within Tasman, for better long term outcomes for all stakeholders.
53. On page 7, paragraph 28, Mr Griffiths concludes there is no need to integrate this consent with the previous global river works consent. From Fish & Game’s perspective there are outstanding unresolved issues in relation to riparian willow removal or re-growth through spraying that are a common concern to both consents. In other words, whether riparian willow is removed
mechanically of chemically, is immaterial to the ensuing habitat impacts this can have on water temperature, pool loss, trout food and the like. Accordingly I disagree with Mr Griffiths
perspective on this issue. Both consents will need to be linked in the same manner to the Environmental Management Plan that is to underpin all Tasman River works into the future.
Murray Tonks
54. As with Mr Griffiths, the evidence of Mr Tonks does not examine the physical habitat impacts of willow removal through chemical means on brown trout habitat. For reasons outlined above, this is a deficiency within the applicant’s evidence that has not been resolved. Issues of concern to Fish & Game in relation to chemical riparian willow removal remain outstanding from the global rivers activity consent, and have not been addressed by the applicant.
55. Mr Tonks also states in paragraph 256 that consent term should stay at 15 years, despite the officers report recommendation of a 10 year term, and that the setting of consent duration should be considered in relation to a Council herbicide program that has been running for over 40 years. I disagree with this analysis, as the application is also for a substantial amount of annual aerial river fairway spraying, which is a new activity (several trials only have been undertaken). This issue is discussed further under relief sought (consent term section).
RELIEF SOUGHT
56. Willow clearance: Consent conditions suggested during negotiations with the applicant
following the global river works activity consent hearing that were aspirational in nature and are related to this herbicide consent included:
17
Fish and Game will be consulted with at least 5 working days prior to undertaking mature*
riparian willow removal (within 5 m of water’s edge), when removal exceeds 3 consecutive trees (i.e. trees next to each other). *Note: mature defined to be in excess of 400mm basal stem diameter and this condition does not apply to layering, or removal where stump will be left to regrow rather than treated with herbicide.
Willow will be allowed to regrow amongst rock riprap where appropriate, until such time as willows reach a size that they are likely to cause issues for rock riprap integrity (or in the case of the Riwaka > 4 m height or 150mm basal stem diameter). At such time, following consultation with Fish & Game within recognised trout fisheries they will be removed. Consultation is to occur at least 5 days prior to removal.
57. These suggested conditions were considered by the applicant following the global river works consent application hearing, but not accepted. The applicant did however note that the willow regrowth amongst riprap issue was best addressed through this herbicide consent application. It is submitted that the above aspirational draft consent conditions should also be incorporated into this global herbicide consent to address aquatic habitat impacts of any future riparian willow clearance through chemical means.
58. Consent term: The officer’s report notes on page 54, paragraph 9.120 that this is the first long term consent of this nature, and proposed consent term is of concern to a number of submitters.
It then concludes that 15 years is too long for a consent application of this nature, and recommends 10 years.
59. Fish & Game agrees with this assessment and seeks consent be granted for a 10 year term only to assess how effective the Council is in improving its engagement with stakeholders, producing a robust EMP that addresses our concerns, and in particular that this EMP then brings about institutional changes in river management practices (as signalled in the 2015 Rivers Activity Management Plan) to better provide for adult salmonid habitat within future river control works and this inter-related herbicide consent application within Tasman rivers that support brown trout.
R F G Barrier 18 November 2015
18 References
Binns N.A. & Eiserman F. N., 1979: Quantification of fluvial trout habitat in Wyoming. Transactions of American Fisheries Society, pages 215-228.
Connecticut River Joint Commissions of New Hampshire and Vermont, 2002 (supported by USEPA): Prioritizing Erosion sites for Restoration in the Connecticut River Watershed.
FEMA, 2009: Engineering with nature. Alternative Techniques to Riprap Bank Stabilization. U.S.
Department of Homeland Security, Federal Emergency Management Agency.
Fischenich J. C. 2003: Effects of Riprap on Riverine and Riparian Ecosystems. US Army Corps of Engineers.
Hay J, Hayes J.W., Young R. 2006: Water quality guidelines to protect trout fishery values.
Prepared for Horizons Regional Council. Cawthron Report No. 1205. 17p.
Holmes R, Hayes J.W. 2011: Broad scale trout habitat mapping systems for streams. Cawthron Report No. 1979. 40 p.)
http://www.catskillstreams.org/pdfs/instreamtablepdfs/Riprap.pdf
Jowett, I. G. 1990: Factors related to the distribution and abundance of brown and rainbow trout in NZ clear-water rivers. NZ Journal of Marine and Freshwater Research 24: 429-440.
Jowett, I. G. 1997: Environmental effects of extreme low flows. In: Mosley, MP, Pearson CP (Eds) Floods and droughts: the New Zealand experience. New Zealand Hydrological Society, Caxton Press, Christchurch. Pp. 103-116.
Minnesota Department of Natural Resources 2015:
http://www.dnr.state.mn.us/restoreyourshore/sl/riprap.html
Unwin, M. 2009: Angler usage of lake and river fisheries managed by Fish & Game New Zealand:
results from the 2007/08 National Angling Survey.
Young, R. G., Wilkinson, J., Hay, J., Hayes, J. W. 2010: Movement and mortality of adult brown trout in the Motupiko River, New Zealand: Effects of water temperature, flow, and flooding.
Transactions of the American Fisheries Society 139: 137-146.
