Rusto,
How much rain did you get? It looks to me like improving your overflow protection should probably be on your project list for this year. (You will almost certainly get a bigger rain event at some time in the future!)
Concrete is a great material to form exactly the structure you want. Especially if you have concrete experience.
However, I know there are a lot of good rock quarries in your area. Knowing you, I think you could pick a rock type you like (or your wife likes) and build an attractive rip rap style emergency spillway.
I bet you could get 12" or 18" rip rap pretty cheap in your area.
I called around for some quotes last week, and was trying to get good descriptions over the phone. The lady told me to just go down there and see which of the products looks best for my application. I bet if you checked in at the quarry, they would let you look at the rock before you buy.
Even with delivery, rock should also be cheaper than concrete. (Except for small loads.)
You might be able to ask snrub for some help. I think he has had rock delivered to his place.
Good luck,
Rod
