Corrie Burn weir & Mackalea Burn

Working in partnership with RAFTS and SEPA, via the Water Environment Fund, the process for improving fish passage up the Corrie Burn has started. Following a tendering process Arup, an environment and engineering consultantancy company, were awarded the contract to investigate options for improving fish passage at the Corrie Burn weir near Dufftown. The weir itself, whilst impassable, is not a major structure but the A941 Cabrach road, which lies immediately above, is. There is a supporting wall of sorts between the burn and the road, upstream of the weir, and the major concern is the stability of the wall, and road, if any actions are proposed for the weir.

Personally I think the weir should be removed but I also don’t want the potential liabilities; which will be massive if the road collapses!

However, in order to kick start the ecological and engineering assessments a site meeting was held today with Arup, Diageo (landowners), Moray Council Roads engineers, RAFTS, Spey Fishery Board and myself in attendance.

Site visit at the Corrie Burn. The supporting wall can be seen on the right bank

Site visit at the Corrie Burn. The supporting wall can be seen on the right bank

The Corrie Burn Weir

The Corrie Burn Weir

The supporting wall appears to be built on bedrock but on informal or non-existant foundations. It is possible that the course of the burn has moved towards the wall since the weir was constructed and there is an argument that removal of the weir and realignment of the burn could remove the threat of erosion from the wall, however we will leave that too the experts.

Whilst we had the very helpful roads department engineer on site Duncan Ferguson and myself, along with Brian Davidson from RAFTS, took him the short distance upstrem to look at the Mackalea Burn culvert. Although as the pipes were over 1.5m in diameter we were told it was technically a bridge. The bridge pipes aren’t too much of a problem, they are relatively short and flat, but at the upstream end there is a set of concrete steps.

Duncan and Brian Davidson discuss the Mackalea Burn steps with Moray council roads engineer Alasdair Donnelly.

Duncan and Brian Davidson discuss the Mackalea Burn steps with Moray council roads engineer Alasdair Donnelly.

No one could figure out why the steps were built but there could hardly be a worst design of fish stopper.

Duncan and Alasdair discuss the Mackalea Burn steps

Duncan and Alasdair discuss the Mackalea Burn steps

The steps were less that 1m high so hopefully it will be possible to develop a low cost modification to facilitate fish passage.

There are 8 comments for this article
  1. Bryan Herbert at 5:03 am

    By opening up that additional 10,000m2 if fully utilized by spawning fish what sort of smolt production do you think it could sustain and is it more suitable to seatrout, salmon or a mix of both. If this work does proceed do you have a base line figure of smolt production from before modification so 4-5 years after modification and around 2 years of returning fish to spawn you can go back and see how successful the work was.

    Bryan

    • Brian Shaw Author at 10:50 am

      Hi Bryan,

      It is a relatively small burn so more suited to sea trout, although salmon fry were present in good numbers below the weir last time we looked. At the average smolt production of 5/100m2 there would be an output of 500, although the Corrie Burn is highly productive so I’d expect more. If it was opened up I’d expect it to be teeming (mainly trout) within a few years. We will continue to monitor the burn.
      Cheers
      Brian

  2. Stuart Brabbs at 9:25 pm

    How much habitat will be opened up, Brian?
    Just a thought but if the wall is at risk of being undermined by the burn, is there no chance that in the near future, the Roads department will have to take steps to prevent a collapse anyway and therefore an opportunity will be available for them taking responsibility for fish passage at the culvert/bridge. Seems to me as elsewhere across Scotland, the road engineers of the past have left a legacy of work for the engineers of today and tomorrow! It is only right that they should shoulder the cost of improvements.

    • Brian Shaw Author at 9:59 pm

      About 10,000m2 Stuart, good quality habitat. The Corrie Burn weir was built originally to supply water to a sawmill but the other culvert on the Mackalea Burn was designed by a road engineer! Hopefully we will be able to make some progress with that one.
      Cheers
      Brian

  3. Bryan Herbert at 5:04 pm

    Hi Brian

    The steps above the culvert are simple you just need a good solid tree a chain saw a hilty drill and some fixing bolts. First cut a section of tree that would reduce the width about a third to half width or what you think suitable then use the chain saw to cut out a recess so that it fits over the step then drill and bolt securely down you could repeat this on the rest of the steps or use another section of tree and cut out steps on it and bolt it at right angles to the first tree section. Although I can’t see below the culvert but would it not be possible to put in wooden structures be it substantial tree trunks with area’s cut into them to provide fish passage this backs up the water levelthrough the culvert and up the steps by around twelve to eighteen inches. Combined increased flow down one side of steps and increased level below the steps would ease fish passage. Just my thoughts using natural materials as much as possible and I am sure you would appreciated more options from other readers as the more options put forward the better the chance of getting a very cost effective and simple solution to the problem.

    • Brian Shaw Author at 9:52 pm

      Like your thinking Bryan. We discussed a few options today but the roads engineer has to go and see if he can find the drawings etc first. He did buy into what we were saying although he was quite defensive about any potential damage to the structure. It would be good to do something utilising wood.Thanks for the input
      Brian

      • Brian Shaw Author at 1:04 pm

        Hi Bryan,

        Good news, Moray Council roads department have given us permission to modify the culvert and steps. We are planning cutting a notch in the upper concrete step, fiting a timber side wall and timber fillets to create a chute that fish can swim up. Timbers with a notch will be bolted to the downstream end of the culvert to create depth over the bridge apron. If you are home you are more than welcome to come and give us a hand?

        Cheers

        Brian

        • Bryan Herbert at 1:36 pm

          Brian

          That is good that you have the go ahead to do the work. I am not home until the 24th then only for 3 days before I go away on holiday however I will try to catch up with you and you can show me the finished result.

          Bryan

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