I am an archaeologist that works for the Bureau of Land Management and have been an avid geocacher for the past year (300+ caches as of my 1st anniversay date tomorrow). When I saw the first memo come through about geocaching, I was very worried, as I had JUST PLACED my first geocache on BLM lands! I went to the field office manager (my boss) and told him what I had done, and if there were any concerns regarding this. He told me that geocaching was such a small impact and because it actually INVITES people to explore public lands, he was all for it. He more or less said that we have much bigger things to worry about, like illegal off-roading and impacts from cattle (overgrazing), meth labs, etc.
As an archaeologist, I would see where geocaching on prehistoric or some historic sites could be an adverse impact. I was looking for a micro in Spokane about 4 months ago and saw that it was hidden in an old historic rock wall at a little park. Well, it must have been hidden very well because folks had begun to tear the loose rock wall down to find it. I notified the hider that it was likely missing and that newbies appeared to think it was ok to tear down historic objects in the search, and suggested he archive or move it. It was missing, and he did archive it.
So far I haven't seen ANY IMPACTS to historic or archaeological sites in or on public lands. And, I just found out last week that the US Fish and Wildlife Service does NOT allow geocaching on Wildlife reserves (or was it preserves?). They will take em away...
And one more note about the National Park Service- THEY are the ones who call up our office and TELL us that we have geocaches on our lands and that we should investigate them and remove them if necessary. My boss took this as the NPS trying to force THEIR policy on other agencies (and he wasn't all that appreciative of it). Thank goodness for rational BLMers like our field manager who recognizes that public lands are for everyone's use, so long as we use common sense!
YA