if it ain't broke, don't fix it......... yep, an old saying but hey, it works

Agree with velo. That's a leak in the block where it wasn't plugged correctly when rebuilt some time.

Is the hole in the engine block?  Can you snap a pic of it and post up?  There are plugged oil passage holes near the area you describe... but oil would shoot out of them rather than water. 

post a picture, please.

Thanks for the responses.

The hole is neither in the water pump or the timing chain cover. It sits in the space between the two. It is obviously machined and was obviously filled prior to my monkeying around (because I didn't have this leak before)

I think I may try high heat epoxy to fill it. 

The timing cover should not have a hole at the top.  Any hole in the water pump should be a weep hole.  The weep hole should not leak unless the water pump bearing seal has failed.

Generally the weep hole is on the bottom of the pump but I have seen pictures where some pumps locate the hole at the top... perhaps for better visibility when problems arise.

I had the same problem after replacing the head. I realized mine was a threaded hole, so I found a shallow bolt and copper washer and plugged it ...

Ok...this is an odd question. 

I did the timing chain and water pump. Been fighting leaks from the chain cover (but that's a different story). Anyway, I did it all again, and when the stuff was apart, I noticed a  hole between the top of the timing chain cover and the bottom of the water pump. Its just a hole! Like...where coolant can just leak out. Start the car up...and sure enough...it does!

Am I missing something? Did this used to have a plug in it? What can I plug it back up with?

Any help is appreciated.