In June 2015, a falcon chick landed in the Susquehanna River while learning to fly and was rescued by a kayaker. It later struck a vehicle and died. But these endangered birds will continue to roost below the bridge. Check out (http://lancasteronline.com/news/local/volunteers-pluck-errant-flying-falcon-from-susquehanna-at-columbia/article_33df76fc-1433-11e5-96f4-430ccf7b72c6.html) in the local paper.
You are looking for a small container. It's been muggled enough times that I'm making it smaller so that no one is tempted to place anything in it. You do not need to go very near the water, and the poison ivy is not a problem when reaching for the cache. Please replace with cover.
Congratulations to albsjudge for the first to find.