I'm guessing from your description of "Fishing between a lot of trees in the middle of some water" that you made it out to Cooter's Pond Saturday? I see what you are describing way too often on all the rivers and larger creeks around here. Many of which are not "legal" based on the Alabama Fishing Regulations. I've posted about people leaving bank hooks/set hooks and trot lines before and it has become a sore topic for me. Here are some quotes from the Alabama Fishing Regulation:
"Alabama requires the ends of trot lines within twenty-five feet of the bank shall be made up of at least six feet of untreated cotton. Untreated cotton line must also be used where the line is attached to the bank or anchors. Also all other anchors within twenty-five feet of the bank must be attached to the untreated cotton line. Any line left unattended for 48 hours may be removed by Division personnel and destroyed [220-2-.44 (8)]."
"All trot lines, or any other fishing gear that is left unattended, is not to be left for more than seven days."
If you are serious about it and want to make a difference, here is what I would suggest. Carry a Sharpie permanent marker and some type of ribbon with you. The first time you see a jug/float or a trot line or limb hook, either write the date on it or tie a specific colored ribbon you have on it. If it's still there after 7 days or the trot line is illegal based on the description above, call "GameWatch" at 1-800-272-Game or text "Gamewatch" and a full description/location to 847411.
It only takes a minute and if enough concerned anglers will make an effort, we can make a huge difference and clean up our rivers and streams here in "Alabama the Beautiful"! I can't say what I would do in the case of the jug you saw bobbing around all day, but if you felt it was "unattended" for more than 24hrs based on your visual evaluation and no one else was around... Well, you get my drift!
Sorry for the rant!