tractorboy,
I'd like to re-enforce Bill Duggan's caution above...regardless of Government agencies, look very carefully before daming up a creek. That small trickle of water can one day turn into a raging torrent that can easily destroy most dams.
Find out what the worst case scenario is for that creek in terms of rate of flow, height, and length of time at the maximum flows. Design your dam accordingly but with plenty of margins above worst case. The weather trends are for more and more unusual weather in the future.
Bill is right on...look very carefully before daming that creek.
