Since the pond was only about a year and a half old, I'd stop at your counties NRCS office and see if they can come out and look at the property to determine watershed and design properly sized primary and secondary (emergency) overflows. It won't cost anything. That way you shouldn't have this problem again.
Here's the info on the office:
USDA-Natural Resources Conservation Service
338 South 36th, Quincy, IL 62301
Matt LeMaire District Conservationist
Phone: 217.224.9307 ext. 3