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.
Around here you can leave it on the curb and someone will take it for metal. At worst you can find a guy on FB marketplace, Thrifty Nickel or some such that will pick up stuff for free.