I have been watching magnet fishing and people love to toss stuff over bridges without a second thought on the environmental impact. Hiding evidence I can almost understand but not lawnmowers, car batteries, etc.
It seems deeper fines should be made to discourage this terrible behavior.
Lack of proper disposal facilities and/or fees for using said facilities. Easier to dump something in a lake or in the bushes than driving 40 minutes across town to a special facility and paying $30+ to dispose of it properly.