Two things stands out when interviewing crappie fishermen about river fishing. Water fluctuations causes daily, and hourly, changes in the fishing conditions. Current is the primary reason but rains can quickly change it too. Changes are usually faster in a river than a lake.
The second and most critical fact is that crappie don’t like current. They’ll stay in a river with light flow but moderate flow puts them behind large objects that break the current. In mild to fast current the crappie will move to eddies. The eddies will have still or reverse-moving water where the crappie can rest, hold and feed. A common place to find an eddie is on the downstream side of a sandbar or island. -TH