From The Grand Junction Daily Sentinel:
Remember trout have dealt with high water for millennia. They probably don’t like high flows, preferring to minimize energy spent and maximize calories gained, but they still need to eat. The flows wash more feed into the stream, which can make terrestrial insect patterns more effective for fly anglers. The faster water and the debris carried along also tend to dislodge aquatic insects, and on the Gunnison that means tossing a large nymph, especially something resembling a large stonefly nymph, during high water.
More Gunnison River Basin coverage here.