So are you suggesting genocide will fix the problem?
What's needed is a cultural change to fix stuff like this (honestly, it would fix a lot of other things, too). Enforcement is one option to exact that change by making the consequences of bad behavior front-and-center. Even if said enforcement doesn't create the cultural change right now, it becomes the old "fake it til you make it" philosophy. If you force people to behave themselves with self-serving motivations, eventually it'll stick, and who cares their motivations for picking up trash if they pick up their trash?
If it were up to me:
1. Stop ALL tourism promotion IMMEDIATELY, and defund those organizations specifically responsible for promoting tourism in the Lake Tahoe Basin
2. Enact a 1-year moratorium on ALL public events in the Lake Tahoe basin. No 4th of July fireworks, music festivals, running races, bike rides around the lake, maker's fairs, auto shows, even farmer's markets.
3. Enact a 1-year moratorium restricting access to ALL power boats for non-residents of the Lake Tahoe Basin
4. Enact a 1-year moratorium on all short-term rentals in the Lake Tahoe Basin
5. Enact a 1-year moratorium on all commercial rafting and tubing operations on the Upper Truckee River
That should clean things up a bit.