cowensx2

So your first option is to dam off the creek, and your backup plan is to dig a channel off the creek and create an excavated pond area to the side?

I think you would be safe in doing the backup plan by yourself, as you must have some expertise in earth moving, otherwise you wouldn't have the equipment you describe.

If you plan on the first option, you need to get professional engineering advice on the design of the dam, and most importantly the size and placement of principle and emergency spillways. Contact your local NRCS office and see if their engineers will come out. They are typically free.

If your creek is fed by 9,000 acres (14 square miles) of drainage, you need to plan to handle a tremendous flow of water during storm events. You indicate the creek floods, but receeds quickly. The latter point is not as critical as what the maximum flow is during storm events. This peak flow is what will blow out your dam.

Think in terms of passing all the water you see flowing through the creek during a storm, though a tube placed in your dam. I've got a 6 ft diameter drop structure and 4 ft diameter outflow tube in one of our ponds that only drains a couple square miles. I would guess that you will need a much larger capacity system in your pond.

I would be very surprised if you won't need to get permits to construct a dam across this creek. Plus make sure you consider the potential for damaging downstream structures if the dam should fail.

There are several contractors who know what they are doing, and often post on this site. Perhaps they will comment also. Hiring someone like that will be well worth the investment.

The other thing to consider is that this stream likely has a resident population of fish, and those will end up in your pond.

Bill