Where’s the Wear’s weir?

There was minor excitement in Durham – and some consternation amongst the rowing fraternity – when river levels dropped rapidly overnight last week.  The river had been very low for some time but was 20 cm lower on Wednesday morning (28 June) due, we learned, to a failure in a sluice gate on the weir just below Prebends Bridge.   It does not look very dramatic in the picture above (a temporary – but not wholly effective – repair had been effected a couple of days earlier) but, as the hydrograph below shows, it was enough to alter the levels to a point where rowing becomes difficult.  The following two days were wet and miserable and the rain caused levels to increase again (note the steep rise on the evening of 29 June as floodwater washed down from Weardale) before gradually tailing off over the next few days.  My photograph was taken in the afternoon of 2 July when levels were back to normal.

“Normal” is, however, a tricky word to apply to any river, so diverse are the alterations to which they are subject.  For me, the ponded section of the Wear upstream of the weir is all I have known and the view of the cathedral looming over the Fulling Mill and its weir is the quintessential impression of Durham, immortalised in J.M.W. Turner’s paintings.  Without that weir there would be no rowing on the river – an important “ecosystem service” within the city (see “Bring on the dambusters …”) – yet that dip in the hydrograph on Tuesday morning offers us a rare glimpse into what the river would have looked like in summers in the far past.  Rowers would be not be very happy were this to pesist but perhaps canoeists would prefer faster-flowing water?  Maximising the ecosystem services that a river provides often involves a trade-off between competing needs.

River levels in the River Wear at New Elvet (NZ 272    ) from 27 June to 2 July.  The orange line indicates the point at which flooding may occur.   From: https://flood-warning-information.service.gov.uk/station/8288425

I saw the opposite situation on the River Tees at Egglestone, just downstream from Barnard Castle.   Turner visited this location as part of the same trip that took him to Durham in 1797 and he sketched the view of Egglestone Abbey which he later worked up into a painting and engraving.   In his pictures you can see an old paper mill, what appears to be a weir across the Tees and open ground on the steep land in front of the abbey itself.   The view today is quite different: the mill is still there, albeit in a dilapidated condition and there is thick woodland on the river banks which completely obscures the view of the abbey.   There is also no sign of the weir but the mill race that diverts river water through the mill can still be seen, though water only flows through when the river is high.

I did wonder if this meant that the weir had been completely washed away since the mill had fallen derelict but another possibility is that the weir is artistic license on Turner’s part.  He made his sketch in 1797 but there is no obvious weir in the drawing that has survived.  The painting on which the engraving is based dates from about twenty years later, and it is possible that the weir was added to the composition, based on memories of other localities that he visited on that trip (including Durham).   The presence of a weir also cannot be confirmed from a painting by Thomas Girtin from about the same time but it is possible that he, too, worked up his watercolours some time after his sketching trips and relied on hazy memories.  And, as we know that Girton and Turner were acquainted, Turner may have fed off Girton’s interpretation of the scene, compounding the intital error.

Egglestone Abbey near Barnard Castle.  Engraved by T. Higham after J.M.W. Turner. 1822.   Image released under Creative Commons CC-BY-NC-ND (3.0 Unported)

The other possibility is that we are not looking at the same river as Turner or Girtin.   The river we look at today is downstream of major reservoirs at Cow Green and on two tributaries, the Greta and Balder, none of which were present when they visited.   Cow Green, in particular, was designed with regulation of the water supply in mind, in order to ensure that there was enough for the industries in Teesside.  One consequence is that there is more water in the Tees during the summer now than when Turner and Girtin visited.   Maybe a weir would have been necessary at that time to keep the water level high enough to feed the mill race during the summer?

So here, as in the Wear, “normal” is a difficult word to apply.   First impressions are that the river is now in a more natural state than two hundred years ago because an impediment to natural flow has been removed.  When we look more closely, however, we see that the river we see today is, in fact, a different type of “abnormal” to that which Turner and Girton sketched.   But we also need to remember that Turner and Girton’s interpretations are not entirely trustworthy guides to the past either.  There is much to be said for walking backwards into the future but occasionally this may mean that we trip ourselves up …

The view across the River Tees towards Abbey Mill and Egglestone Abbey from approximately the same place as Turner’s view.  The mill is just visible amongst the trees in the middle of the picture.

Reference

David Hill (1996).  Turner and the North.   Yale University Press, New Haven and London.

 

So what?

so_what_exactly

And so to Trento, and the Use of Algae for Monitoring Rivers symposium.   I approached with mild trepidation (see comments in “The human ecosystem of environmental management …”).   The last time I attended, Diatom Jihad was just getting started, and hordes of fundamentalists were swarming over the plains of scientific reason, eliminating any apostates who dared suggest alternative methods of evaluating the condition of freshwaters.   To be honest, I was probably part of that horde, certainly in the early days, though I think that the True Believers always doubted my ultimate loyalty to the Holy Books produced by Lange-Bertalot, Krammer, Witkowski and their acolytes.

I have, indeed, had my own vision on the Road to Damascus (forgive me for mixing my religious metaphors).   It was, in reality, the culmination of several conversations and much thinking but it can be encapsulated by a comment made by a biologist from Wessex Water, one of the utility companies who operate sewage works in the UK. I had been part of a team working on the River Wylye in Wiltshire and we were discussing our results.   She looked up and said (I am paraphrasing now): “I’m not disagreeing with what you are telling us [i.e. that the river had higher concentrations of nutrients than was ideal for the ecology]. But we need to justify the price rises that would result from improved effluent treatment, and the public don’t know what diatoms are”.   She had put her finger on a very major issue: that many of us involved in applied ecology are so focused on the fine details of the ecosystems that we study, that we lose sight of the bigger picture.

I tried to emphasise this in my talk and the cartoon above follows Billy Wilder’s maxim: “If you’re going to tell people the truth, be funny or they’ll kill you”.   And, to be fair, I was not the only person who made this point.   Jan Stevenson from the University of Michigan gave us a good overview of the current situation in the USA and also emphasised the need to relate the changes in diatom assemblages to ecosystem services and, if possible, to determine thresholds in responses that help to develop consensus amongst stakeholders. So perhaps the winds of change really are now blowing on both sides of the Atlantic?

Towards the end of my talk, I used the phrase “healthy streams are slippery streams”, used by Emma Rosi-Marshall of the Cary Institute for Ecosystem Health in New York.   She is using this phrase as part of a campaign to raise awareness of the role that benthic algae play in ecosystem health. Phil Harding, the co-author of my talk, saw this written on one of my slides and commented that one of the sampling locations that his team visit regularly in the English Midlands is called “Slippery Stones” – a beautiful site on the edge of the Peak District. Is it too fanciful to suggest that this place actually has a name that reflects the quality of the freshwater ecosystem?

Slippery-Stones

“Slippery Stones”, the actual place name of a site on the upper River Derwent in Derbyshire, UK.

Dipping a toe into the River Jordan

I came across an intriguing short paper recently which got me thinking again about a topic that I wrote about a year ago. I was intrigued, at the time, by how ecosystem services dovetailed with the ideas of ecosystem health that preoccupy my working day and suggested, provocatively, that there may be some instances where stakeholders might not thank ecologists for the high quality ecosystems that we want to achieve (see “More about ecosystem services” and “Ecosystem services … again”).    There is a class of ecosystem services called “cultural services”, which includes uses such as education, amenity and, intriguingly, spirituality.   I have been searching, subsequently, for good examples of rivers and lakes providing “spiritual” ecosystem services and here, at last, is one hiding right under my nose.

The paper describes use of the Jordan River for baptism, and the problems caused by the ongoing regional conflicts along with environmental degradation.   The river is the de facto border between Israel and Jordan and has been heavily militarised since 1967, with access to the river limited to just three locations, one each in Israel, the Occupied Territories (West Bank) and Jordan. Problems are compounded by the extensive use of the Jordan and tributaries as a source of water for this semi-arid region, and by discharges of semi-treated sewage into the river from Israel.   This has reduced the flow to a muddy trickle, about one tenth of its natural quantity. This, combined with the pollution, hardly makes the river a desirable place in which to be totally immersed.   Whether the river was ever crystal clear is open to debate: in 2 Kings chapter 5 we read of Naaman, a general from the eighth century BC, objecting to being told to bathe in the Jordan to cure himself of leprosy.

Jordan_at_Bethany

The River Jordan at Bethany, Jordan (the church of John the Baptist on the left hand side) with, on the right, the baptism site at Qasr al Yehud in the Occupied Territories (West Bank), seen from the Al Maghtas baptism site in Jordan (photos: Heather Kelly)

Reading this article reminded me of one of the stranger instances in my professional life when a local clergyman asked for my advice on a location for an outdoor baptism in the Durham area.   I suggested a couple of locations where the river was accessible from the bank and not too deep, whilst being deep enough for a kneeling person to be dunked.   I also suggested, from my knowledge of the river, a careful search of the river bed in advance in case there was broken glass, and recommended that the initiate kept his or her mouth closed to ensure that they did not swallow too many bacteria.   I was not being consulted on the theology of baptism, else I might have queried whether a purely symbolic act needed all this fuss and bother. And, indeed, we might ask what a baptism candidate gains from being dunked in the Jordan that would not have been achieved using a font full of chlorinated water.   Such issues are for another blogger on another day.

Varanasi_puja

Performing puja in the River Ganges from the ghats at Varanasi, October 1984.

Indeed making catty comments about other people’s attitudes to sacraments whilst writing about the Israel-Jordan border has a deep irony of its own.   Would that people historically had shown a little more tolerance to other people’s spirituality, the world would be a far more peaceful place.   My intention, when I started writing this piece, was to highlight how rivers can play a role in people’s spiritual life. We don’t need to understand or accept the beliefs of those people, just to recognise that some places – rivers, sometimes – can hold great spiritual significance and that we, as guardians of those rivers, need to respect this.

I was also reminded of my own visit to the holy city of Varanasi in India, thirty years ago, when I watched Hindus using a different (but equally polluted) river as part of their observances.   It was difficult for me, as a westerner, to understand the significance of the river to Hindus yet all around me there were people who clearly saw this river as integral to their worship. The problem, as with so much in this modern world, lies in not understanding what others regard as important.   Some questions, it seems, cannot be answered by scientific rationalism alone.

Reference

de Châtel, F. (2014). Baptism in the Jordan River: immersing in a contested transboundary watercourse.   WIREs Water 1: 219-227.

Ecosystem services … again

Sorry to bang the same drum repeatedly, but I want to return to the theme I explored on 17 November, when I suggested that not all situations where man interacts with water will necessary benefit from “good ecological status”.   Last time, I used the example of angling, suggesting that, as fish yields were a consequence of productivity, there would be situations where anglers, an important stakeholder community, would prefer enriched ecosystem to the pristine ecosystems that us Fundamentalist Ecologists yearn for.

I also mentioned in my post on 9 November that other recreational users of water, rowers, for example, might not appreciate the removal of weirs, even if some conservationists regarded this as desirable.  Having written these words, I started to wonder if there were any situations where conservationists themselves might not regard good status to be a desirable outcome?

I think we can take as a general rule-of-thumb that protecting natural habitats and restoring degraded habitats to their “pristine” state is a general goal for conservation.   But maybe there are exceptions that go against this general dogma?   Perhaps, too, conservationists sometimes overstate the link between high quality habitat and naturalness?  One example that springs to mind is the recent spread of the otter.  For a long time, we regarded the spread of the otter as a sign of the gradually increasing health of our freshwaters.  Yet it is now so widely distributed, often in rivers that are not pristine, that we need to re-examine this assumption.   Evidence for the ink between otters and toxic pollutants that biomagnify along the food chain is quite good.  However, some other types of pollution, such as a moderate amount of enrichment by organic and inorganic nutrients might not be problematic and, indeed, by boosting overall productivity, might raise the carrying capacity of the habitat.  I have never seen this idea explored in detail but it would be worth a look.

Another example of an organism that might actually thrive from enrichment is an unprepossessing but rather rare aquatic plant called Najas marina which is found in only six locations in the UK.   One of these is Upton Great Broad, a habitat that is far from pristine.   Yet it appears that Najas marina is a relatively recent arrival to this lake, only being recorded after the onset of enrichment.   This, of course, creates a conundrum as restoring Upton Great Broad back to more “natural” conditions might bring other conservation benefits, but what would happen to the population of Najas marina if we did this?

I recall a situation that arose in the early 1990s when Northumbrian Water were required, by EU law, to build a sewage works at the mouth of the Tees, rather than discharge raw sewage as they had been doing.  The problem was that the sewage provided an excellent food supply for worms on the tidal mudflats which, in turn, sustained an internationally-important wading bird sanctuary.   This location was, indeed, protected by a different piece of EU legislation, the Birds Directive.   Work on the wading birds of the Tees Estuary was led by Professor Peter Evans of Durham University whilst I was still working there.  I have, however, not seen any of this published in a peer-reviewed journal, which is a shame as it would provide a thought-provoking case study of the trade-offs that many involved in applied ecology have to face.   Here, as in the other examples I’ve mentioned, it might well be the case that an ecosystem at less than good status is actually of greater conservation value than one that has been restored back to good status.

At this point I had better duck my head below the parapet and wait to see what kind of responses this generates.

ecosystem_services_v_WFD_#2

A diagram illustrating the relationship between conservation and ecological status.  The EU’s Water Framework Directive expresses the quality of an ecosystem in terms of five classes, from “high” to “bad”, with good status being the theoretical target that all water bodies should achieve.

References

Ayres, K.R., Sayer, C.D., Skeate, E.R. & Perrow, M.R. (2008). Palaeolimnology as a tool to inform shallow lake management: an example from Upton Great Broad, Norfolk, UK.  Biodiversity and Conservation 17: 2153-2168

Mason, C.F. & MacDonald, S.M. (1990).  Impact of organochlorine pesticide residues and PCBs on otters (Lutra lutra) in eastern England.  Science of the Total Environment 138: 147-160.

Bring on the Dambusters …

Mild annoyance lies behind this post.  I’m writing as I travel home from a two day conference, organised by the Chartered Institute of Ecology and Environmental Management with the title ‘Ecosystem Services 3: Rivers – A Framework For Action’.  The meeting had several interesting papers but, at times, lacked a hard critical edge, exemplified by the following example:

Two of the early speakers commented on the problems of physical modification of rivers, noting that in-stream structures such as weirs often present serious obstacles to the migration of salmon and other migratory fish.   In theory, you should be able to construct fish passes around these weirs so that the fish are not obstructed.  In practice, however, many fish passes are not particularly successful.   ‘Why not’ suggested one questioner after the talk (representing Natural England, I think), ‘just remove the weirs altogether and restore natural flow regimes.’   This suggestion was greeted with applause and even a few ironic cheers from parts of the audience.

About six months ago, however, I joined the local rowing club in Durham. ‘Recreation’ is a ‘service’ that society gets from our rivers, just as much as nature and wildlife, the primary focus of interest for this audience of conservationists.   Rowing here depends upon the weirs across the River Wear (you can see one of them in the classic view of Durham Cathedral which I posted on 29 July. (This view, itself, could be classified as an ‘aesthetic’ ecosystem service).  There are about 500 members of the rowing club and, at a guess, between 500 and 1000 students in University and College crews.  That’s a huge constituency whose interests are in conflict with the ambitions of many conservationists.

rowing_on_the_Wear

Rowing on the River Wear, July 2013. 

I had come to the conference to see how this type of conflict of interest would be resolved, and was a little surprised to see how little it featured.  Only three of the 18 speakers addressed the issue of trade-offs between different ecosystem services and only half made any reference to public participation or stakeholder engagement at all.  I heard a good example of constructive engagement with anglers on the River Itchen during a workshop session but this was a situation that could be sold as a ‘win-win’, with both anglers and conservation benefitting.  For the most part it was conservationists talking to conservationists without anyone to challenge their assumptions.   I left feeling with a feeling that life out there in the real world may not always be this cosy.