Think positive, in most cases you should be able to free the victim. What happens then? The victim and equipment will float downstream and need to be retrieved somehow and that means downstream safety. On a serious foot entrapment, there is a very strong likelihood that the victim is seriously injured. Chances are also high they will not be able to swim effectively - they are certainly going to need some help. Downstream safety is essential. Ropes that cross a river can be quite dangerous for unsuspecting boaters entering the rapid. We certainly don't want to clothesline anyone. Anytime you work with ropes, set safety upstream as well and make certain rescuers have a safety knife that is easy to access on their person.