The weir behind Minnishant on the Culroy Burn isn’t a complete barrier to migration but I’ve no doubt that it stopped some fish from progressing upstream and it was on our list for some improvements in the next year or two. At well over 1m high and 10m long and built with tightly laid river boulders, it was fairly stable apart from a small hole that was opening up in the middle (which we felt may offer fish a resting pool) and at the toe of the weir where it was cutting back and would eventually have made migration difficult or even impossible. Surrounded by large trees and a large cliff face at the upper end on the right bank, I thought it would require some serious engineering to ease this obstacle but I was wrong.
The massive spates that came in November that damaged our green bank engineering efforts upstream have also wreaked havoc on the lower burn. The weir is no longer an obstacle as the high flows removed the massive trees on the right bank ripping them out and allowing the bank to disappear downstream. The weir is now buried under tonnes of cobbles and boulders that have deposited on the inside of the bend and a new channel has been cut around the weir. The heavily sedimented pool upstream of the weir has scoured and cleaned and is now a series of run/riffles and pol habitat but it’s clean for the first time in years.
Further upstream trees have fallen and blocked the burn, reverting the flow causing further erosion to some areas. Last April, Muir and I cleared a log jam that allowed tonnes of fine sediments backed up behind it to move. The Board then cleared some fallen timber during the summer. This area is unrecognisable today and is clean and diverse habitat offering fish cover instead of a bare featureless stretch. It is still essential to address the source of the silt upstream and we will discuss this further with the board shortly. Stopping the sediment input should return this to a diverse and productive habitat.
The force of nature is unstoppable and despite our efforts to stabilise erosion on one particular area of this burn, the huge spates overwinter have sorted some problems and created others. Downstream of the A77, the Board installed fencing about 10 years ago and this too has largely been damaged. The landowner is prepared to fence his boundaries but doesn’t intend to fence the water margins again without assistance. We will now consider what course of action we recommend to the DSFB for the immediate future.