As stated above, chances are slim to none that you won't have enough water, that time frame is usually well into run-off. If by some strange stars-not-aligned circumstance you don't run, the Dearborn may be an option. It is the "little Smith" and is fun and beautiful, but short. The issue would be, if the Smith isn't running, then likely no small streams in the area will because the only way there won't be water is if it's still all frozen up high (cold and dry in the mountains).
The others above have already mentioned the Mo, below wolf creek and the other usual suspects. Just remember most creeks and small streams are closed for fishing until the 3rd Saturday in May so be sure to check the regs for each stream before you fish. Those that are not closed are listed in the regs.