Question
is it possible to construct a pond in a wetland? I want to construct a drainage system that empties into the pond with some sort of overflow drainage control

Answer
I am sure it is possible. There is a lot to consider. The location of the pond has to be lower than the wetland, then comes the problem of overflow it would have to be pumped or on the low side of the pond. I would really have to see it to see what you are up against.

             Sorry I can't be of much help, sounds like a good idea to get rid of some wetland an make use of it in a pond. What about digging in the weland itself?

           Keep Ponding
             Leigh