I have dug half a dozen or more ponds here locally in central MO over the last ten yrs without any permits, including my own 15 Acre one, but Im sure that changes from state to state. that being said, if and when you do go ahead with the project, whether permitted or otherwise, never mention the swimming and fishing interest, that immediately makes it a recreation pond, consider it strictly a water source for irrigation, cattle, or fire suppression. Ag use will get you by a whole lot of red tape that a recreation pond wont. js
Good Luck!

All the really good ideas I've ever had came to me while I was milking a cow.