Does the creek run continuously? Or is it seasonally dry?
The reason I ask is, if it runs continuous you could just stack rocks or rip-rap through the cut up to the desired level of water. The water would rise and fall along with the creek flow, but back up into the pond area at least part of the time.
When I was a kid (with too much time on our hands in the summer), we would play in the creek and take boulders in a riffle area and stack them up. It would back up a nice pool of deeper water.
Where you only want a limited amount of water in the pond area, anything to restrict flow of the creek water might do what you need.
That is if the creek flows pretty much year round instead of seasonal.
