I worked on a couple of creeks where we had fish traps/racks that were permanently installed. We walked the streams weekly, the whole anadromous zone. The racks stopped bedload movement. Every year we had to dredge about 100 cubic yards of gravel from above the rack. But the word thing is that the configuration of the creek stayed the same. Riffles were in the same place, pools were in the same place. How the gravel moved through system but left the bed intact always amazed me.