More water means more food and more opportunity for a trout to use the whole river, from bank to bank, for feeding in the drift and for ambushing bigger food forms.
. . . So, fish the edges when big flows are recent. Fish the edges too when water clarity is at its worst, because slow seams near the bank often have the best chance to clear up, as sediment falls out of the current.
. . . However, given high water with decent clarity, I do not fish the edges any more than normal. And during the last few months here, I’ve caught more trout in the main flow than in the bank water.