Have a look at this photograph from last Friday 6th October 2011 (rather blurred, my apologies).
On Friday the leaves in this very productive feedlane were a nuisance but not an insurmountable problem. What would happen is that the artificial fly kept getting concealed from the fish during the drift. Then the leaves would interfere with the tippet. Finally, on picking off to recast, sometimes a leaf would be caught on the fly, which required instant intervention to avoid twisting up the tippet into a corkscrew in miniature.
The remedy was to simply keep trying but ensuring that the fly was a long way from the target fish before attempting to pick off. Picking off too close with a leaf being moved unnaturally would scare the fish. Not perfect but to fish where the fish are needed the fly to be in amongst this floating debris and to be stealthy required this careful and slower process of letting the fly drift a long way down from the fish to avoid the risk of disturbing them.
But just observe with me for a moment. Look how long that tell tale line of drifting leaves is! In summer the influence of the feedlane is not so obvious. It is easy to see it to a foot or so below the last of those trailing stalks. Now, with all these leaves, it is clear that the feedlane extends way, way down stream. Next summer, the intelligence gained from this reconnaissance will lead me to make sure I start my approach from "way, way down stream" where the feedlane opportunities really begin and not to just start fishing up there by the trailing stalks!