I've only fished Herrington once that I can remember. There were three of us and we were in our mid 20s so this was a LONG time ago. We really didn't know what we were doing and where we were fishing. I do remember catching a few bass early then switching to panfish stuff once it got sunny and hot, then having to jump in when it got really really hot. We were back in some area where there was a pretty soft flat and the water had decent visibility but wasn't crystal clear. All of a sudden we see three or four really long shadows moving together in fairly shallow water. Doing what young\stupid and not young\stupid fishermen do, we cast whatever we had at them and of course got zero attention. They were gone as fast as they came but we got a really good look at them moving around before they swam off. I figured they were carp but if they were they were HUGE carp. These looked like 3-5 ft shadows in the water. Of course the shadows probably do get bigger the longer you've had time to think about them. ha!! But they were much larger than your standard lake fish regardless of what the size was. I really hadn't thought of it for years until I read this thread. I don't think it was monsters and it probably doesn't have much to do with what the OP saw, but it was a cool memory regardless.