What is the biggest carp you have caught? in inches or pounds. The MN state record is 55 pounds and 5 ounces, I wouldn't be surprised if you had 30lb carp in there. Also in the spring you should try fishing for northerns, northers spawn in shallow weedy bays, I have seen northers run up shallow rocky creeks from rivers. You probably have large pike spawn in your pond. If you had one small northern you have larger ones just waiting to be caught.
You pond is a pond, the definition I heard somewhere, and go by myself is - a lake has a stream or river flowing into it, a pond does not. As you did not mention a river inflow, I deduce that you have a pond.

One last thing, when is CarpFest '04 and is it open to the public? I would love a chance to tie into your monster carp.