Have you ever used a river or stream to dispose of a dead body?

I've been thinking about that for the ex-wife, but I heard that murder and dismemberment are frowned upon. 

No.  The currents tend to dislodge them from the bottom and they get discovered on the banks. 
Deep lakes and reservoirs are the way to go

Not a human body, no.

Not yet

No that would be a waste of a perfectly good body. It's better to bury a body in a peat moss bog because peat moss bogs have preserving properties which means that after 20 years you can dig the body up and call it Mummy.  Also it's not good to throw a body in a river or creek because it can contaminate the water with a parasite and if someone drinks the water they could catch Beaver fever. Cheers!