I am new to this forum but have a background in geology and a creek that I am also considering damming. The important consideration here is flood stage and sediment load. With much drainage area at all your pond will overflow the dam. If you install only two culverts for drainage the odds are the dam won't last. Two common dam types are first a dirt dam with a clay wall and an overflow built into a hillside. The other type of dam is like a low water crossing. This is made of cement which allows flood stage water to run over it. This can be constructed in an arced wall or with a road on top and sloping sides. This is best for high rates of water flow with large sediment loads, it allows the creek to scour the sediment buildup in the bed and not silt up.
If you want a culvert to control the high water level you could use it in conjunction with an overflow built into the hillside. The culvert will need a plate of steel welded around it like a big washer. This will keep water from channeling along side of it and the overflow need an apron to keep flood water from washing back in under the dam.

Good luck, my creek has washed out a couple of dams in the last 100 years.