Low flow at Stair Dam on the Ayr

We fitted two timber baulks to Stair Dam today in order to help salmon over during periods of low flow. Last year there was such a shortage of water that the fish built up in the stretch downstream while upper beats complained of no fish. With the hydro fully operational since last year, it was now more important than ever that we took steps to help fish over. SEPA and the Hydro operators were supportive so with the river low at the moment, we took the opportunity to get this work done before we have any rain.

Of course salmon can make it over this dam in higher flows without too much difficult but with springs becoming typically drier during April and May and most summer’s not much better, it was time for action.

To help with the work, the gate to the lade was opened fully diverting some of the flow off the dam. We manhandled the timber into position and set about laying out to achieve the best results possible on a rough weir face. The timber baulks were 200mm x 200m x 4.5m untreated Larch and they are anchored onto the face of the weir using a dedicated waterside resin that secures the galvanised studs to the face of the dam. Once set, the nuts were tightened down and the excess threaded studs cut off.

Setting out and fixing the baulks to the face of the weir. The flow has been reduced by opening the lade to make work easier

The first baulk partly completed, we moved onto the second

Back to fix the extension to the 1st timbers now that the resin had set

Work finished and levels coming back up after the lade was closed down to a minimum

These timbers are set at an angle across the face of the dam and will concentrate the flows behind the baulks. This will ensure that there’s adequate depth for salmon to make to inver the weir even when we are facing prolonged dry spells. That’s the aim anyway so we will monitor and see how they fare.

Looking from downstream, the angle of these baulks is more obvious. The depth was estimated to be around 5″ – 8″ behind the timbers for three quarters the length of the weir. That should help salmon get over. These baulks also  concentrated flow which will act as an attraction to running fish.

Our thanks to Ricky Shearer for his assistance and cutting timber today.