Been reading on here for years! Thanks to all who contribute!

I am looking into purchasing a 30 acre piece of ground in Missouri. A good portion of this land is in the flood plain. A very small creek runs on one side of the land and small small drainage ditch/wet water creek runs parallel to this creek and feeds to creek. We have two options, dam the very small creek (3-4 feet wide, 1"-3" deep), or build up the bank outside of the creek and use the drainage ditch to feed the pond. Either way we will be creating a pond in an area that floods from the back up of a much larger creek down stream. This larger creek downstream feeds the Mississippi River.

My question is can you build a pond in a floodplain?
Can you dig a pond in floodplain?

Who should I contact to make sure? DNR? Core? If you have any knowledge on this or would like to see pictures let me know.

The purchase of this land is contingent on being able to build a pond.

Thanks in advance.