Big browns are snag magnets! They will go for cover quickly once hooked. I was playing one once while drifting in a swift current near Helms when it got all tangled up in a down tree. I couldn't turn the boat quick enough and drifted on down stream and my line snapped :o Well, as I was feeling sorry for myself, I looked back and saw a twig of the down tree twitching and jerking so I went back to investiate. My trout was on a 3 foot leash fighting the heck out of the tree! Amazingly, I was able to free and boat the fellow, all 28 inches of it. I would not think that a hooked trout would lay or hide on the bottom, these fish will fight! you may have had one getting down into some roots or grass though. There are some big carp and gar in that river, no telling what you hooked!