Shit man...you're not dredging so the fucking Navy can navigate your canal. Investigate the cost of a crane barge with a clam bucket. At least know the cost and the options before you give up on your home. Good luck to you.
i have 2 x 25kW impeller pumps sitting here that can move 100 gal/min (IIRC) you could "quietly" suck water from the main canal towards the dock and "flush" some depth... only used a couple of times for testing. $2500 new each, FS for 2k for both