Video

It used to divert water through Scotton Mill (built in late 18th century). More background and rationale for removal here: www.wildtrout.org/assets/reports/Scotton-Weir-Removal-Press-Release-July-2022.docx

@@WildTroutTrust Thank you.

Overall, the impact on either increasing or decreasing flood risk will be hard to detect in this situation. The same amount of water will flow down the river at the site where the weir used to be (compared to the amount that would flow over the top of the weir when it was in place). Also, when the weir was in place, it wasn't set up to create flood storage by deliberately pushing water out onto the floodplain; so that wouldn't have been providing any downstream flood protection. What can now happen is a natural re-emergence of more varied habitat as riverbed material can now be redistributed by spate flows. This was artificially prevented when the weir would, previously, intercept those spawning gravels and cobble materials.

What ecosystem has been destroyed? Especially when viewed in the context of the weir (combined with all others built) damaging the river “only” 200 years ago… Compared to the un-impounded river that had developed over the preceding ~12K years since the retreat of the last ice age.

What ecosystem has been destroyed?! Well I can’t put that better about ignorance than that. You clearly don’t understand action without consequence! The species that live within that niche have a reproductive series a lot less than ours. So 200 years as you put it for the weir (although most have a much earlier date and I doubt that you can be conclusive about this one) is a seriously long time for aquatic organisms that rely and live in these environments. I could go on and on but really. Think about what you are affecting or effecting before making such bold statements. Just to add it has an impact on predators such as birds ie kingfishers etc. So tell me that a trap wasn’t the best solution.

If you think that I’m taking the micheal, you only need to look at why the Severn barrage wasn’t built.. due to stopping the tidal flow over sites which would expect it and also Sutton harbour in Plymouth, although that one was allowed. So yes ecosystems do exist where you you may not see them.

Thanks for your passionate contribution. One way to put it better would be to explain which particular valuable ecosystem, specifically, has been damaged? I also wonder how likely the ecological consequences of building the weir for industrial purposes were assessed at the time? The science of ecology has progressed quite significantly since the time of construction. If you have an interest in the ecological consequences of weirs, there's an article on our site here which will give at least an introduction to the kinds of things that are taken into account when deciding to remove engineered channel modifications: www.wildtrout.org/wttblog/why-presume-remove-weirs-river-dove-case-study

Well this is the point I first brought up about that every action has a consequence. Yes I agree that how many centuries ago a major ecological impact was had by the construction of the weir. What I’m trying several times to put to you is that the current (or as in this case past) ecosystem which has existed for a very prolonged period of time (upstream of the weir for 800m as you said) has now been removed. Surely this is just as devastating an impact as construction of the weir all the centuries ago. I get your enthusiasm for righting wrongs and agree in some respects. However we should also consider the environment which is currently established and I personally feel that is what has been ignored. Hence why I was offering a less extreme solution. I feel that getting me to explain what ecosystem is superfluous as that’s exactly what should have been done by yourselves. I’m not an expert nor is anyone else on a section of river bed in a given area unless I’ve studied it, I do however know that such a major change is going to have a major impact, as was when the weir was constructed, as you have said yourselves.

It was dammed to serve a long defunct mill. The proliferation of “run of river” dams during industrialisation is a not very well known yet significantly negative impact on rivers and streams. Not only do they fragment breeding populations of a wide range of species by cutting off access, they also disrupt the process of riverbed material transport. This degrades habitat and reduces species diversity as well as increasing the risks of local extinction of certain populations (risking a loss of genetic diversity and the associated resilience/adaptability of native species). The purpose of the video is to highlight projects such as this one. It is part of highlighting these - well established but little known - ecological impacts of weirs. Thank you for the opportunity to continue this exploration of the issues outside of the confines of a video lasting just a few minutes.

Agreed - that’s what the question mark is for in the thumbnail picture. It’s just that many people would automatically assume that it was a kind of vandalism.

It was flowing over the top of the lowest points of the crest of the weir (with a large, long still pool of water with little turbulence or energy upstream of the weir).

Hi there, I understand it was supplied to the project by the current owner of the site.

I did put the photo on the Knaresborough history Facebook site, so that will be where they got it from. That photo was taken in 1919, approximately

What difference are you expecting in a dry summer? Do you think all the water would be held up behind the weir like a lake (if it was still there?). If that was true - which it wouldn’t be - what would happen to the riverbed downstream of the weir? Weirs don’t change the amount of water flowing down a river and having a layer of anaerobic silt built up behind them doesn’t do any favours when the weather is hot and dry.

@@WildTroutTrust short section of river dried up vs very long section dried up

The weir wouldn't significantly change the length of dried up river channel (it might even increase the length of completely dried up channel downstream if you had such extreme conditions that no flow could get over the weir crest). Instead a weir might create a localised increase in the width of wetted channel on the upstream side - but this would also be at the expense of slowing the flow and causing stagnation (which would raise the water temperature). The combination of stagnant flow, increased water temperature and the nutrient-enriched sediment trapped on the upstream side of the weir would strip oxygen out of the water causing fish kills. In contrast, when hot dry weather causes low flows in natural riverbeds without weirs, the flow retreats to the narrowest sections of deepest channel cross section (sometimes known as the thalweg). This keeps a supply of constantly flowing water with higher oxygen levels and a lower risk of fish or invertebrate kills. The benefits of that situation can be increased by making sure there is enough shade from riverside vegetation and that the riverbed habitat is as complex as possible. In higher flows, there is also much better dispersal of nutrient-enriched sediment - instead of it collecting in a large "hot-spot" on the upstream side of the weir.

The same amount of water goes over top of a weir as runs down the river without that same weir. What will now happen during large downpours is the downstream movement and replenishment of clean spawning gravel that would previously have been trapped behind the weir.

You do realise that the river was there millions of years before the weir was built?

High 5

If you reduced excess silt inputs (where they exist, this is a good idea); why would you need to dredge? For a set gradient and flow a river will create a particular cross sectional width and sinuousity by redistributing bed material. The result would be the exact habitat features all river species evolved to thrive in since the last ice age.

I don’t really agree with your analysis. There is demonstrably (look on the map) good, sinuous river channel habitat upstream of the weir. A major point of the removal was to specifically benefit species other than fish (did you see the part of the video where previously impounded, uniform habitat is now being used by a much wider range of terrestrial species as well as aquatic ones that previously had no use for the artificial, uniform habitat created by the weir?)…Signal crayfish simply walk round or even climb up weirs - so leaving it in place would be completely ineffective as a means of slowing their spread. Never is it claimed that Duffield is the sole destination for Salmon - merely that they HAD previously been journeying up beyond there for over ten thousand years until that barrier was built very recently when viewed on that mind boggling timescale (something many people find remarkable). To suggest that there’s more than enough spawning habitat (with a uniformly low risk of pollution) isn’t correct; so there is a clear and highly significant benefit of creating a wider, connected patchwork of potential spawning sites - especially for locally-adapted breeding sub-populations. Providing opportunities for that site selection specialisation can help maintain genetic diversity that may, otherwise, be diluted away when forced to spawn in other parts of the catchment. Think of it as diversifying your risk in an investment portfolio - both in habitat types and genetic variation terms. Other points come to mind, but I wonder what the motivation/agenda might be for the, not factually correct, polemic? Paul.

@@WildTroutTrust Hello Paul, We have met and I am sorry that we might appear to be in conflict over this issue. We do agree on some points - maintaining genetic diversity and diversifying risk for example. You have stated that "the goal of the Salmon is to reach the productive spawning grounds of the Ecclesbourne", suggesting more than strongly that this is their sole destination. Your stated timescale ignores the range of events which have reduced or even halted the migration of Salmon throughout the River Trent catchment and specifically the River Ecclesbourne. As you say, many people will find the stated timescale remarkable but it is very much a "red herring" in this fishy discussion. I am aware of the less desirable abilities of Signal Crayfish but something was helping to protect the River Ecclesbourne White Clawed Crayfish population. My suggestion was to take active steps to protect the river from further invasion now that has to some extent have been facilitated. With regard to the River Ecclesbourne and your instruction to "look at the map" where I am sitting writing this comment is just over one mile from the river. If I stepped out of the door and walked to the edge of the village I would be able to see the course of the river in the valley bottom. I travel most of the length of the river several times each week. Your - "sinuous river channel" might begin to account for actual river length, which on the map is only a little over eight miles. I fish several stretches of the river and walked another section of it for the first time earlier this week. I have some insights into the hydrology of the area and have even visited the soughs I mention in my previous comment. Wirksworth has streets named after wells, which dried up as the water table was lowered. You question my motivation and agenda but I have stated facts as I know them, from research and practical experience. I stand by what I have written as an accurate, honest account. Now I have to ask you - why the does the Wild Trout Trust wish to deny the presence of spawning Salmon in the higher reaches of the Derbyshire Derwent and its tributaries? I had met this before our exchange here. Stating the "goal" (your word) of returning Salmon is the Ecclesbourne gives weight to your video but is not wholly true. To suggest that anglers and others are not being truthful regarding their observations and experiences is actually quite offensive.

Thanks for the comment. I'll give a little more site specific context which would have cluttered the simple messaging of the video. Two separate landowners with different requirements for their farm business. The zoom from the drone footage focusses in on a small plot with tubes which were visible. Actually, there has been much more extensive planting without tubes and guards, closer to the channel at the very downstream end of the project site, currently almost impossible to capture but, given 2 or 3 growing seasons, will start to become more apparent. The upper field is still maintained as traditional wet meadow, so some low density conservation-style grazing using native breeds, providing a mosaic of habitat surrounding the beck. This landowner is not averse to natural regen occurring, mostly on the true right bank.

Thank you for the kind feedback and and many thanks for your membership support - it is hugely appreciated. Paul

Thank you - really glad you liked it.

Very kind of you to say and you’re very welcome.

Thank you!

Sure I read in Anglers mail today about a guy fishing for barbel with fly tackle & squirmy worm & sure it was this guy who caught a salmon on this same river!

Thanks for checking it out Max

You’re very welcome and thanks for taking time out of your day to leave your feedback.

Many thanks for your generous feedback