What’s this about staying at the lake after diving:

You should get a hotel or campsite somewhere around the lake at Lake level. You will need to stay at lake level for some time after the dives. Diving at altitude and at lake Tahoe creates a challenge regarding decompression and flying after diving. Leaving the lake after diving the lake requires you to drive up and out of the Tahoe basin. This means you are flying after diving. Your instructor will elaborate more on the subject and your Advanced diver manual contains more information regarding the subject.

Most dive computers today calculate time to fly information at altitude. Check your computer’s user guide.