Shinyguy: OK, so two people have told me this cache is on NPS land and shouldn't be there (actually, I think they're right), and one has threatened to turn me over to the authorities for endangering wildlife by placing a cache in this pristine wilderness area (I don't agree so much with that one). That'll teach me to try and help the sport by adopting a cache.
Row the Potomac is now gone for good. Hope to still see everyone out on the river, but don't bother to bring your GPS.