I also use chemicals to kill bugs. It kills the "bad" bugs but it also gets some of the "good" ones. It's for the greater good. I've probably created a huge algae bloom with all of the nitrogen I've introduced into the water table.
When I have extra lawn chemicals leftover, I'll go out front of the house and dump them down the storm sewer. I thought of that one day when I was dumping some used motor oil down it.