ITHACA, N.Y. — At the base of the gorge walls at Ithaca Falls, which were mostly clear of debris after the site was cleaned in 2015, are several feet of dirt, leaves, rocks, and brass butt ends of shotgun shells. All of it this debris, which spills onto the nearby trail leading to the city's namesake waterfall, is contaminated with toxic levels of lead again — an issue that has been plaguing the city for years.