A big mistake made by fly fishing beginners on rivers is not fishing coloured water. After a spell of heavy rain, a rain-fed river will colour up (normally brown) as silt is washed through by the extra water. In these conditions, it’s easy to be put off – how an earth will any fish see my fly and feed in those conditions you may be thinking? Well, stop right there! Coloured water can produce some of the best days fishing on rain-fed rivers, particularly if the river has been low and clear and a good few days of rain has fallen to stir things up.
The best time to fish is normally when the river is just starting to fall and lose its colour but still has a good bit of colour to it, you may often hear these conditions referred to as “fining down”. In these conditions fish that have been holed up in the low clear conditions come out to feed with confidence. The colour in the water disguises both you and your casting and the fish often feed with confidence. Although you may get fish to take a dry in coloured water, upstream nymphs or wet flies often produce the best results.
If you fish chalk streams you may never face these conditions as the underground aquifers that supply the water act as giant buffers, delaying and filtering the water to an even temperature, flow and colour.