Yes it is a shame what and how much trash, people throw out. In four hours, we usually fill two dumpsters, and have more bags/items beside the dumpsters.
Our lake has an interstate over it, and a highway that forms the damn. We find everything from trash, tires, lots of fishing line, to bongs.
Last time, I filled my then boat up four times with 55 gallon trash bags of trash. I left myself enough room too drive. That was a 17' boat. I drove around and picked up the full bags that the crews walking the bank, left on the shoreline. That way they didn't have to carry them all the way back.