The mine is at least another 10 miles farther than the watershed, maybe more. It really has nothing to do with Lake Tahoe so you can stop worrying about that.

If you call ahead of time they are usually happy to give you a tour as long as someone is around. Were you aware of the shareholders meeting on June 22/23rd? I believe the registration is on the "contact us" page of their web site. Perhaps your visit could be timed for this event?

I used to live in Lake Tahoe and know quite a bit about the surrounding areas, CA and NV so if you need some recommendations please let me know and would be more than happy to to share my knowledge.