The post yesterday talked about how weirs can be used to manage silt. There is of course a more direct way of getting rid of silt - dredging.
Here you can see recent dredging of one of the river bus quays. The barge has the ball-diamond-ball of a vessel restricted in its ability to manoever. And at night it has the red-green-red lights - even when anchored (hmm - well at least you notice it).