1999 Chevy Blazer Strange Coolant leak

My '99 blazer began to run a little warmer than normal two days ago. I was mindful not to let it overheat, but it ran about 30-40 degrees warmer than usual. For two days I flushed the coolantsystem(with water once each day). After a short drive, the blazer belched steam and leak a large majority of its water. Upon first inspection it appeared to be leaking from the bottom of the radiator, on the driver's side. Is there a plug of some sort, on the nearly unaccessible, on the underside of the radiator? I had decided to flush the dex-cool completely and start fresh with an all make mix, other than the dex-cool. Besides a pressure test(and moving the vehicle), is there a way to locate this large leak? Also, the resevoir remains full throughout the leaking and adding more water, might I have a clog? Or does the system notwork like that?