Tahoe isn't regulated, you just go shore diving, but you will need to rent your gear in the Bay Area or Reno. On the Nevada side you must use a surface marker. If you want to boat dive you will need your certification card, and nothing more. Nitrox obviously will require a nitrox card. Keep your depth shallower, and if you use a computer that compensates for altitude you will be plenty safe. There isn't much to see deeper in Tahoe anyhow. Rubicon Wall goes down hundreds of feet, but I never saw a need to go below 70ft and much of our dive was in the 50ft range. We scootered pretty far along the wall. There really isn't that much to see in Tahoe. Would probably be more fun if collecting crawfish.