What's the River Usk like in this hot spell?

I am sure it has not escaped anyone’s notice that we have not had any rain for some weeks now and this has had obvious impacts on the flow on the river Usk. Looking at the height of the river today it is about 2 inches below normal summer flow levels. (Please bear in mind just how much water is abstracted from the river at Brecon for use in the Brecon & Monmouth Canal – a hefty 30 million gallons a day, or at least a third of the river’s flow.)
The low flows effect the temperature of the water and how much oxygen is available in the water for the fish and the temperatures remain high in the middle and lower reaches of the Usk. All returned fish take longer to recover in warm water that contains less oxygen so fishermen should be very careful when returning trout.
The Wye and Usk Foundation are so concerned about the water temperatures that they have suspended fishing tickets on their passport beats until water temperatures fall. At Gliffaes we have fast moving (thus better oxygenated) water on both our top and middle beats and I think are still safe to fish. In these conditions and at this time of the year when the days are so bright and warm the only times to fish are very early in the dawn and late in the evening. So, an early dinner and then a sharp dash down to the river is required and it is still light till around 9.30pm.
Looking at the last couple of entries on the fishing book it appears that most fishermen are having success on a nymph as most of them are on holiday and have no real desire to get up at dawn to fish the early morning rise. As I type this post it is increasingly grey outside and rain threatens so I can only hope that conditions on the river will improve soon.
Pictured above is a large blockage on the Top Beat that two of us cleared last week by taking advantage of the low flows in the river.