We made the most of the good weather today undertaking essential surveys that we had hoped to complete last year but couldn’t due to the weather. Gillian and Helen headed to the Upper Doon surveying for Pearl Mussels while Gordon and I headed to Auchendrane to assess the weir for porosity…. or alternatively Fish Passibility. I don’t have details or photos from Gillians’ survey so that will have wait for another blog post at a later date but I do have photos from Auchendrane. Gillian and Helen came to assist once they completed their survey.
The crest of the weir is indicated by the white line in this Google Earth image.
Measuring the height and depth at the crest of the weir
There are concerns that this weir slows fish passage upstream, especially at low or compensation levels and particularly the larger salmon. The aim of this SNIFFER barrier assessment was to determine a score that puts things into some sort of context, that is repeatable, comparable and based on hard evidence rather than speculation or opinion. We measured the height of the weir, the flow velocities, depths and gradients. These will be used to determine whether fish can pass and at what flows, all based on well researched parameters.
This is a long weir at over 77m
It is a long weir and steep in places. The force of the current and algae on the face made it tricky to take measurements whilst remaining safe but as you can see in the photo above, our risk assessment required lifejackets and throw lines at all times. We haven’t completed the analysis yet and in any case, can’t report results on this page but rest assured we are looking forwards to at last knowing the true impact of this weir on migration. Hopefully if there is a problem, we will be able to use our results to justify improvements.
Helen crossing well upstream of the weir to take measurements.
There were a few trout rising and we saw quite a few salmon parr in the lade. In the warm afternoon sunshine, mayflies were hatching but not in great numbers yet. Perhaps Spring really has arrived at last.
