Keep Tahoe blue by eating great tasting food. Works for me. Introduced around the beginning of the 20th century, there are hundreds of millions of crawfish in Lake Tahoe. Considered an invasive species, they pollute the crystalline water which, ironically, is the reason why they are world class crawfish. They have a cleaner taste than creole mudbugs, and are wonderful by themselves or in a gumbo.
Easy to catch, just go down to a local pier with a small trap and some bait and wait a few hours. After emptying the trap a few times over a day or two you should have enough to make a meal.
Some of the details:
As for bait, almost anything will work. Hot dogs, chicken, bacon, salmon heads. Crawfish are not picky. Some folks like to protect the bait so that the crawfish do not run off with it (yes, they can escape), and to make sure it gets spread around. A couple of ideas are to use a can of tuna with some holes pierced in it, and to protect food in an old sock.
Where to place the trap. A convenient place is suggested as you want to be able to empty it several times over a 24 hr period. five to fifteen feet works great during the summer months when the crawfish come up from deeper water. Just off a pier or in an spot easily accessible by kayak works well.
Keeping them alive. As you start collecting the crawfish, you do not want the ones you catch first to die before you have collected enough for a meal. In a confusing turn, a bucket of water will not work. The crawfish will use up the air in the water and suffocate. A wet towel or newspaper placed on top of them in a cold environment is an option, or using a bait bucket left in the lake so that the water can change out.
Cooking them. 
Heavily salt the water and boil them for ten to fifteen minutes. That’s basic. For more of an experience, add crawfish boil mix, potatoes, corn, and beans to the water at appropriate intervals so that everything is done at the same time. Drain with a colander and dump onto a table covered by newspaper.
Interactive eating always screams party and this is no different. Add a beach, beer and no shoes and this is about as good as it gets.