Not necessarily. I checked with F&G when I recently caught a fox. They gave me specific areas I could release it legally and told me how far I needed to take it to make sure it didn't return. Actually, I had two friends who were happy to come shoot it if and when I did trap this animal. Unfortunately they were both out of town this week, and I don't have a gun (or the killer instinct to dispatch the critter.)It is illegal to release a predator anywhere other than the exact place that it was trapped.
I agree with the previous comment that drowning is NOT a humane way to kill.