Please pull up the 100-year flood map for your creek. I would build the pond embankments just outside of that range. (In many states, the rules for building in the floodplain are MUCH more stringent.)

In Kansas, the rules for pumping water from a creek into a pond are much less restrictive than pumping groundwater. It is also usually much cheaper and easier to pump from a creek. Does your creek have water available during July and August? If so, try to review the regulations in Texas yourself or ask the NRCS agent about supplemental water usage from the creek.

(In my experience, a NRCS agent needs to be an expert in about 100 different topics. If you get one that is an expert in 40, then you have a good agent. However, it is impossible for them to be an expert in every single topic under their purview. So you kind of need to gauge if the agent seems to be an expert on the questions you are asking.)

Good luck on your new pond project!