There are no simple answers to this question since survivability can depend upon many variable factors. The water temperature. Any injuries sustained prior to drowning. Length of submersion time. Check with the office of Emergency Management where you live.
Many municipalities have police or fire departments with their own dive rescue squads.
It may be possible to join one of these. If, however, this is not possible you may start your own dive rescue team or join us. If you decide to start your own team, you will have a long hard road ahead of you. Don't be discouraged, however, because we will help you if you wish. Unfortunately, many people think that after having taken a sport agency rescue diver specialty course, they are qualified to do this type of diving.