floods

November 21 2022

November 2022 flood

ashleyriver black billed gulls, black-billed gulls, floods, management

Intrepid operations manager and volunteer Grant Davey donned his wet weather gear on Saturday to report on the state of the river birds and today (Sunday) he took another look. Here is his report.

This was the biggest November flood since records began at the gorge in 1972. Peak flow at the gorge was 246 cumecs at 3pm on Saturday. It hit as nesting season was in full swing.

Colonies of black-fronted terns had started nesting, black-billed gulls had settled in with a few nests established and wrybill and banded dotterel chicks were appearing. But many birds still sitting on nests had no chance when the flood came through.

So, nests and chicks have been lost but we know many birds will bounce back and nest again, and some will go elsewhere.

It is likely to be a while before water levels go down enough to do a bird count.

Other damage is loss of traps – probably about 20 were washed away.

Black-fronted terns (tarapiroe)

Overall, probably all the tern nests have gone – we had mapped 41 which I think were still occupied, two of these had hatched small chicks. My estimate is there were around 36 nests still to be found at the known colony sites. So we probably had more nesting pairs than last year. We knew of 15 nests which had been predated (rats, stoat, harriers, hedgehogs) or abandoned because of predators.

In the Railway area where there was a large tern colony there are very few terns around today, and the colony downstream from Smarts appears to have lost all nests.

Black-billed gulls (tarapuka)

The places where the gulls were have been covered in water, but there are still a couple of hundred of them in the general area. Hopefully they will settle down and nest. At the estuary the BBG colony is still there. I think there are a couple of hundred more gulls nearby. Also, several hundred gulls in a paddock not far from the beach settlement. Probably Waimak refugees.

Wrybill (ngutupare)

We knew of only one pair of wrybill still on a nest which has probably gone. Some of the wrybill chicks may have survived.

Banded dotterel (pohowera)

There would be probably tens of BD on nests along the river, and a lot of chicks. Probably all the nests will have gone, some of the chicks will probably be OK.

The Marchmont – Smarts island, which we saved by working with a gravel extractor and ECan, was still sticking up nicely yesterday afternoon. But it did go underwater as peak flow came through. It’s possible it will be a site for new nests.

The below shows nest destructive floods during the nesting season – above 100 cumecs at the gorge seems to be bad and 50 cumecs will get some nests. We might have to think about making islands higher. And doing more with gravel extractors to make deeper channels around them.

March 18 2022

Gravel mining/extraction

ashleyriver floods, management

Submission to Environment Canterbury Catchment Subcommittee

Re: Gravel mining/extraction

The Ashley-Rakahuri Rivercare Group has for some time been raising concerns about gravel mining in the riverbed.

Any changes to this bed jeopardise the environment the braided river birds need for their survival and multiplication. The protection of this environment is the prime aim of the Group.

Despite our 20-year working history on the river, during which we have had considerable assistance from Environment Canterbury, we have rarely been consulted relative to gravel mining. The points we have made to ECan do not progress significantly to fix the system and address the damage being done to the river.

In our opinion, if large gravel takes continue, the Ashley-Rakahuri River will be reduced from its natural braided state to a single-channel riverbed where bird populations decline as has happened to the Opihi further south.

Since 2010, according to an ECan document, there has been a marked increase in gravel removal from the Ashley-Rakahuri to feed infrastructure because of the earthquakes, subdivisions, roading and farming. ECan also notes that the bed level continues to lower.

The Ashley-Rakahuri is a small, fragile river and we believe it cannot withstand such a “rush for gravel.”

We believe the river’s chance for survival as a braided river will be improved by an overhaul of the gravel consent process. Hence, we are pleased to note ECan has started a review and we wish to be part of consultations in all aspects of gravel mining.

ECan describes its mission to: “Work with partners and other agencies to protect the health of our environment to ensure a sustainable and prosperous future for all of us.” A failure to do so will lead to a loss of birds on the river.

The river nesting birds face many threats, including predation, human disturbance, habitat loss and the vagaries of weather and flooding. They do not need the added threat of habitat destruction by gravel mining.

This will not be news to many committee members as our Operations Manager Grant Davey** has explained the problems and solutions to councillors and staff on a number of occasions via submissions, direct discussions and presentations. However, we are concerned about the poor response, leading to few positive outcomes for the river. Hence, we attach our submission to restate issues of concern around gravel mining.

We are available at any time and look forward to further consultation, and to assist to protect the health of the environment.

Sincerely
Sue Mardon
Chairperson
Ashley-Rakahuri Rivercare Group

** Grant Davey is a geologist and holds a Post Graduate Diploma in Environmental Science that included papers in hydrogeology, hydrology and environmental impact assessment. He worked for about 4 years with ECan as a hydrogeologist and briefly as a groundwater consent investigating officer. He has 28 years’ experience in the mining industry in exploration, mining operations, environmental practices and safety.

To: Environment Canterbury Catchment Subcommittee
From: Ashley-Rakahuri Rivercare Group
March 2022
Subject: Gravel mining/extraction

Key concern: Retaining the river in its natural state still has lower priority status than the considerations of commercial mining interests.

Applications for gravel mining have not kept up with recent and more informed management ideas and practices. There is a vacuum of expert environmental and mining knowledge being required and applied to the policy, rules, applications, consents and river operations. As a result, the care and protection of the natural river environment is only vaguely mentioned in consents, operations are being inadequately monitored, and adverse environmental outcomes have been overlooked.

While the picture of a loader and truck removing gravel from the riverbed may look benign, gravel mining is acknowledged internationally as a major threat to the existence of braided rivers, along with damming, and constrictions. Consequently, it has been banned in a number of countries.

The main Issues:

1.Gravel removal is not conducted in a sustainable way – how much gravel is there in the river?

To date we have not seen sufficient evidence to justify the extraction of half a million cubic metres of gravel – the sum of applications now before ECan.

The Ashley-Rakahuri is not regularly topped up with large quantities of gravel.

Some is added irregularly by flooding and natural eroding of banks, but this has been reduced significantly by tree planting on the berms.

Crucially, for the health of the river, accurate data on the amount of gravel must be kept for gravel to be removed at a sustainable rate.

Before the May flood of 2021 ECan halted gravel takes, yet these have restarted even while opinions differ on whether there is enough gravel available.

An ECan report states: “The Ashley has a relatively low estimated annual supply of gravel … from the foothills. Volumes extracted are not replenished at the same rate.”

We submit that gravel mining should not proceed until more accurate information is available relative to gravel reserves currently existing in the riverbed

2. The application and consent process

To prevent destruction of the river environment a significant application and consent process around site characteristics and cumulative impacts is required.

All gravel mining consent applications must include an operational manager with the required (and current) Quarry Manager’s qualification.

At present, applications are filled out by consultants who know how to tick the boxes. There is no demonstrated knowledge of appropriate braided river management and history, or of consultation with important stakeholders such as the Ashley-Rakahuri Rivercare Group.

Detailed specifications of each mining site should be required in applications, along with operational intentions for each.

Operational criteria for the protection of the natural river environment should be written in all consents.

We submit that any gravel mining application must involve on-site management with a current Quarry Manager’s qualification, and that indigenous river habitat be safeguarded by best practice intentions which are clearly stated in all applications.

3. What happens during gravel mining?

Removal of gravel often leads to:

creation of fast-flowing single channels, often with steep banks which prevent young birds from accessing water/shingle interfaces
shallow braids, essential for bird feeding, are lost
island height is reduced, making bird nests more vulnerable to any rise in water levels
flow around islands is cut off allowing access for predators.
easy vehicle access is created, opening up opportunities for human disturbance

Our studies show there are five to six times the number of birds nesting in braided areas compared with other ‘single channel’ parts of the river.

We submit that consents contain a description of the braided state in which mined areas should be left once mining is completed.

4. Supervision / monitoring

When a consent is granted, there are few restrictions. Companies tend to mine in whatever way likely to prove most cost-effective for them. Environmental consequences are not adequately prioritised and catered for.

As mentioned, this can be remedied by a more in-depth application and consent process, accompanied by regular supervision, monitoring and, if necessary, policing to ensure adherence to consent criteria.

It would be prudent to appoint an on-river gravel ranger, with a background in the environmental sciences/mining to advise and monitor.

We submit that proper compliance procedures be included in all consents, and that these be appropriately implemented.

5. Safety

Large gravel trucks with trailers on public land can be a danger to walkers, cyclists and trappers, particularly along access roads into the river. Points where stopbanks are crossed are notable high hazard sites. More signage and efforts to alert the public to truck movements is essential.

Truck routes to gravel sites should be chosen so that the negative impacts of dust / noise are avoided / minimised, particularly close to housing and recreation areas.

We submit that safety aspects are given greater attention in consent applications.

5. Integrity

Any company applying should have a clean record with ECan.

We submit that the operational history of gravel mining applicants be taken into account in any consent approval procedure.

6. Stakeholder consultation creating ‘win-win’ associations

Some gravel companies have worked with us to rehabilitate their mine sites. We are grateful for their consultation and cooperation. The end result has been the maintenance of good habitats for bird feeding and breeding. However, this has not been the case with other gravel miners. As outlined above, the desired environmental outcomes from all gravel mining operations will only be assured by well-informed environmentally aware management plans.

We submit that all gravel mining consents on the Ashley-Rakahuri River require consultation with key river stakeholders such as ARRG.

Summary

For the survival of the Ashley-Rakahuri River in its natural form, there is an urgent need for ECan to prioritise environmentally based decision-making when considering gravel mining within the river. In order for this to occur, professionals trained in the environmental sciences and best practice mining should be at the helm and oversee the whole process.

We submit that there is need for a complete overhaul of the gravel mining consenting and operational procedure within the Ashley-Rakahuri River.

October 7 2021

AGM: Outgoing Chair Report

ashleyriver black billed gulls, black-fronted tern, floods, management, Predators, research, Trapping, weeds, wrybill AGM

by Nick Ledgard, outgoing ARRG Chair

Welcome everyone to this AGM. The Ashley-Rakahuri Rivercare Group was formed in 1999, and became an Incorporated Society in 2005. My report is usually an adaptation of the summary from our annual report for the last season – in this case for 2020-21. That is contained in this document – written by myself and Grant Davey. But this year, I am going to depart from that format, as this will be my last report as Chair of this Group – after 18 years in that position.

Have we succeeded? Looking back over that time, one has to ponder over what has been achieved, and that of course has to be measured against the Group’s objective. Our mission statement is ‘To protect birds and their habitat in the Ashley Rakahuri River, while recognising essential river control works and sympathetic recreational uses’. Therefore our primary objective is to restore, or at least maintain, the indigenous bird species which breed on the river – the wrybill, black-fronted tern (BFT), black-billed gull (BBG), banded dotterel, pied stilt, and South Island pied oystercatcher – and hopefully in the future, the black stilt. In this respect, if I was an outside interviewer, my first question would be: ‘Well, after over 20 years, (with you heading the Group for 18 of those), have you succeeded?’

Monitoring. One cannot answer that question without good monitoring, and we have done a reasonable job on that score. We use two measures. One is annual population or number counts via our annual survey in mid-November, and the other is breeding success, measured by annual productivity – which is number of fledged chicks per nesting pair of birds. The ways in which we have measured these are far from perfect, but as we have done population surveys since 2001 and productivity monitoring since 2005, we can put some certainty on trends.

Population or number counts. This is what the data show us. Looks great up to 2015, but the decline since then is not attractive. The high figure in 2019 is an anomaly caused almost certainly by the Waimakariri River being in constant flood and our river acting as a refuge. We hoped it was also a sign of bird numbers returning to former levels, but the count for the following year (2020) indicates that not to be the case. So, all this graph really tells us is that we are at least maintaining bird numbers during this century. Needless to say, we sincerely hope that this year’s survey (November 20) sees a good increase in counts. But, we are only 6 weeks away from that date, and so far this season, numbers do not look encouraging. This could well be due to the record floods of late May / mid June having shaken up the core aquatic insect food supply, which is taking more time than usual to get up to speed. We will soon see.

Breeding success – productivity and chicks fledging. This is much harder to estimate, as chicks are hard to follow through to fledging. However, we have attempted to do so with wrybill, BFT and BBG since 2004. The results are as follows. Once again, they don’t appear to show a significant improvement over time – possibly because survival between egg hatching and chick fledging has not been overly threatened. However, if one compares the number of chicks fledged in the first 6 years of monitoring (2004-2009) and the last 6 (2015-2020), one finds that wrybill have increased from 3.5 to 5.9, and BBG from 75 to 394, whilst BFT have not changed much – from 16 down to 14. So, it appears that we are enabling more wrybill and gull chicks to get into the air, but not tern chicks. Probably the best take-home message of all about this is the importance of long-term monitoring – we may be the only volunteer group with such impressive records.

So, I look back over the years, and my term as chair, and reflect on not as good an outcome as I would have hoped. But I am aware of population and breeding monitoring on other braided rivers, and in comparison to those, our results generally look a lot more positive, Plus, I am an optimist, and I am sure the future will show an improvement, and that our efforts to date to have been vital in maintaining a base to attain that.

Weeds. In the first graph I held up, apart from the bird numbers, we follow the rise and fall of bare gravel area – thanks to the mapping skills of Grant. When I first saw this and the close correlation between bird numbers and gravel area, I immediately went back to Grant and asked him to check his figures. After 40 years in research, I had never seen such a close correlation between an effect and a likely cause. But it is a real one, which underlines the importance of weeds in retaining bird numbers on braided rivers. Hence, I see the control of weeds as our greatest challenge in the future if we are to attain our mission statement. The record floods of May/June have swept the riverbed as clear as I have ever seen it. But by Christmas there will be a green tinge to most of it, and if nothing is done (coupled with the likely absence of another record flood), we will be back to the autumn 2017 weed infested situation within a few years. Needless to say, we are thinking hard how to make use of the unique weed control opportunity which the floods have presented us. And we cannot just sit around and discuss it – any cost-effective solution will have to be applied within a year, while the weeds are small, starting after February once the birds have finished their breeding season.

Predator control. This is by far the biggest single activity undertaken by the Group. At present we have 236 traps alongside the river, maintained by 18 volunteer trappers, while around the estuary we have another 129 traps maintained by 8 trappers. This gives a grand total of 365 traps and 26 trappers checking them every few weeks – a very impressive effort. Once again we have to ask – has this been successful? According to our records, we have caught 3353 predators since 2004, and without doubt have saved 100s of birds from gruesome ends. If one looks at trap-catch over time (numbers caught per 100 trap-nights), we averaged 1.3 predators trapped annually for our first 6 years (2004-2009), whereas for the last 6 years (2015-2020) the figure is around 0.5. This is comforting, but once again the long-term picture appears to be one of maintenance of what we would like to say are ‘low’ numbers, rather than one of a steady decline towards elimination. Hopefully this will change for the better soon, as last week we met with a contractor who is going to write a plan for almost doubling our trap numbers alongside the river (paid for by ECan).

River management. As most of you will know, we have had cause to contest how the river has been managed in the past – with too much emphasis on flood control at the expense of environmental values. A braided river must always have room to move. Plus we have also not been happy with the some of the results arising from commercial gravel extraction. Grant has led that discussion with ECan, and I am confident that we are seeing light at the end of the tunnel.

Awareness / education. I consider that we have been very successful in improving awareness at the public, education and institutional decision-making level. Most people are now aware of the birds on the river and how we are assisting their improved well-being and long-term survival. This is due to multiple awareness activities – our website and Facebook postings, displays, media and magazine articles, interviews, talks and Ppt presentations to councils, schools and community / interest groups. In this annual report we list 45 promotional activities undertaken in the last year.

So, I look back over the last 20 years with a degree of satisfaction relative to achieving our mission, plus many happy memories of the process followed to achieve that.

Thanks. Last but never least, I conclude with thanks to all members of the Group for the work they have put in over my time. There are far too many to name individually. But there are some I must mention: Joan Miles for her work as Secretary, Sue Mardon for her excellent work as Treasurer; and in the trapping arena, Peter Whitehead and Geoff Swailes and the impressive volunteer trapping team. Then there is Grant Davey with his mapping and record-keeping skills. Any volunteer group can only utilise the skills that are present within their membership, and Grant has significantly enabled us to look far more professional than we actually are. When I started in the early years of this century, the words ‘social media’ were little used, but they are absolutely vital in holding one’s own today. So thanks to Sonny Whitelaw and Steve Attwood for looking after our website and Facebook outlets. Then there is our one-and-only sponsor, Karikaas Dairy Products Ltd. Most importantly ongoing thanks are always due to ECan and their Regional Park staff, the Waimakariri DC and DOC. We might be the body which makes passionate pleas on behalf of the public, but without their professional support it would be very hard to make meaningful progress.

August 23 2021

Group Update, August 2021

ashleyriver 4X4, annual survey, black billed gulls, black-billed gulls, black-fronted tern, floods, management, Predators, research, Trapping, Trapping, weeds, wrybill

by Nick Ledgard, ARRG Chair

The last Update was written earlier this year in January, so a fair bit of water has gone under the bridge since then. Quite literally actually, as the most significant happening affecting our local river over the last 6 months has been the record floods of late May and mid June.

Down on the river. The floods not only cleared the riverbed of virtually all weeds, but also ate into the margin of the vegetated berm which lies between the open fairway and the marginal banks. This has widened the fairway in places, but it may well be less braided than before. Despite the floods, the berm remains considerably wider than it was a few decades ago, and as stated publicly many times recently, a braided river must have ‘room to move’ in order to maintain the braided riverbed habitat which the birds need for successful breeding and feeding. Although we now have a ‘weed-free / clean slate’ riverbed, the future challenge is how to keep it that way.

Bird movement. After February, our core indigenous breeding bird species (wrybill, black-fronted tern (BFT), black-billed gull (BBG), banded dotterel (BD), pied stilt and S. Is pied oystercatcher) move out to warmer winter locations. Most retreat to the coast and the northern N. Island, whilst some of the banded dotterels cross the Tasman Sea to Australia. Over winter, only a handful of other species, including a few BFT, remain on the river. We have good records of these, as some sections of the riverbed are walked at least monthly by Grant Davey and myself.

Right now, the breeding birds are starting to return. The first wrybill was seen on August 16, and we can expect to find nests from around mid-September. Small numbers of BD, BBG and BFT have also been seen, and some BD may be nesting as they are usually the first to start. Nesting colonies of the gulls and terns are unlikely to be established before mid-October. The May/June floods mean that there are many weed-free sites available for breeding, but that major disruption which was followed by a number of other high flow events may result in a slower than usual return of core foods – aquatic insects and small fish.

Maintaining habitat. Weed invasion remains our greatest threat, as although the record May/June floods swept the riverbed clean, the weeds will rapidly return. Initially, they will be small and more readily removed, so we have new opportunities for sorting out the cost-effective means of controlling them. The riverbed is owned by ECan and understandably, the prime aim of past management has been on flood control. This has sometimes been at the expense of conservation values, such as bird habitat. Hence, over the last year, we have had many discussions about shifting the management focus more towards environmental considerations.

Gravel extraction. This is the main commercial activity undertaken on the river. Although such activity can assist the birds by removing weeds, there are many examples which show that it can also create problems if not carried out properly. In our discussions, we have pointed these out to ECan, who are keen to correct consent deficiencies and improve their oversight. They are very aware that we spend more time on the riverbed than virtually anyone else, and so can act as watchdogs. Gravel extraction has been considerable (some would say excessive) over recent years. It is likely to become more restricted in the near future, as despite the recent floods moving masses of gravel down-river, very little of this is ‘new’ ie., originating from catchment headwaters.

Predator trapping. This remains our major commitment in terms of personnel and operational hours involved – and continues all year round, both alongside the river and around the estuary. Over the last year there have been on average 236 traps along the river and 129 at the estuary, serviced at least monthly by 26 volunteer trappers. Nearly 100 traps were lost to the May/June floods, but thanks to generous cash donations and supply of materials, the majority of those have now been replaced. We are particularly grateful to the Mens Shed at Rymans Healthcare village who have made nearly all the replacement DOC200 boxes.

Trap catch. Over the past 2 years, we have trapped almost 1000 predators, with the dominant species being hedgehogs and rats. However, despite the consistent trapping effort, results show that the trap-catch rate has been static over recent years – at around 0.5 predators caught per 100 trap nights. The composition of predators caught alongside the river was very different to that caught at the estuary. Compared to the river, the estuary had a higher percentage of rats (53% estuary; 35% river), stoats (16%; 6%) and weasels (18%; 11%), but a lower percentage of hedgehogs (9%; 38%) and feral cats (5%; 10%). The reasons for this are unknown.

How effective are traps? We have long suspected that many predators visiting trap sites do not get caught. In order to look more closely at this, we set up a project for a student, Quill Yates. He investigated predator visits and catches over a 2-month period last autumn. Trail cameras were set up at three sites where three trap types were placed alongside each other. Almost 20,000 images were analysed. The main finding was that only 8.3% of predator visits resulted in successful catches. The percentage caught / visit for feral cats, rats and hedgehogs were 2%, 22% and 22% respectively. Too few mustelids (ferrets, stoats and weasels) were caught to allow for any analyses to be done. A detailed report is being written, which will contain recommendations as to how the number of trap-catches might be improved.

Trapping review. A year ago, ECan agreed to fund a review of our trapping strategy, including the possibility of doubling our trap numbers by installing a double line alongside the river. A contractor has been approached to undertake the review.

Human disturbance. We continue to make sure the public are well informed – via media articles, presentations and talks, displays, and our website and Facebook page. In the 2020-21 year, there were 39 different promotion activities undertaken. Earlier this month, all 4WD access ways were mapped, and as in previous years, these will be blocked during the breeding season (September to the end of January).

Finances. The Group is always closely following its accounts and budget situation – and generally, our finances are in good shape. We are now mostly self-funded for our day-to-day existence, with monies coming from donations, our trap making and selling, and sponsorship via Karikaas Natural Dairy Products Ltd cheese sales. Funds for larger special projects usually come from ECan.

Reports. For over a year, ECan has been drafting a long-term management plan for the Ashley-Rakahuri River. This will recommend how we carry on into the future. It is hoped to be able to read this report in the near future. The annual report for 2020-21 will be completed within the next month. This, and a number of internal reports (referenced in the annual report), are written by Grant Davey and myself.

Group structure and meetings. In addition to the normal committee hierarchy of chair, secretary and treasurer, it was agreed in June to create three management teams – operations, communication and administration. It was felt that such a structure will lead to less work required by any one individual. The teams will be confirmed at the 2021 AGM on October 7, together with the member(s) to lead each of them. Our 8-person Management Committee continues to meet regularly.

Finally, this will be the last Update that I write as Chairman. After 18 years in this position, it is time to hand over to someone else.

As usual, many thanks to all our volunteers for the time taken to support our cause.

Nick Ledgard
Chair, ARRG

June 1 2021

May flooding

ashleyriver floods, Trapping, weeds

Ashley Rakahuri River flood 30 May 2021

Left: 4.00pm 29 May. Water flow 4 cumecs.

Right: 4.00pm 30 May. Water flow 966 cumecs.

Photos: Nick Ledgard

June 01

Photos – Grant Davey

Looking upstream from approximately the downstream end of what used to be the Railway island – only a few small islands poking out of the water, bare of weeds. The layout of the river here might be quite different when flows drop. And the effects of gravel extraction look likely to be wiped out – this had diverted at least 2/3 of the flow to the south of the island.

Looking downstream to the “Golf Links” island – this seems to have lost quite a bit of area – it is an island which we have wanted gone, it has mature weed and trees. Unfortunately the river is definitely not going to be going around it.

Looking upstream to the railway bridge. The awful heavily vegetated island here has lost a lot of area.

Looking over the railway bridge to the Cones Road bridge. Again lots of vegetated island area gone.

The small stopbank and trees along the edge of the area north of the Railway island. This shows how effective those willows which grow up from trunks laid along the edge of the berm are – breached in only one place, but the trees remain.

Just downstream from here, past where they had stopped doing this, the river did break through quite a high natural bank. I have/had a trap in the willows just past that bare gravel. I didn’t think this was a spot in danger. Two other traps just upstream from this photo, which I also didn’t think were at risk, had been washed a few metres and filled with sand. Further downstream I rescued a few traps, before the flood, which would definitely have gone.

We are not going to have to clear weeds this year, with the possible exception of a few willows. There doesn’t look to be a massive amount of driftweed around either. The higher islands and the berm, as expected, have attracted a lot of sand – so weeds will probably grow rapidly again. But from what you can see of the lower islands, they seem very gravelly which will be good for nesting and worse for weeds.

Once the river is back to 10 or 15 cumecs I’ll drone photograph between Cones Rd and SH1 to properly see what has happened.

– Grant Davey