Can't speak for tahoe, but here in Utah, I read that total residential water use accounts for about 2% of the total water use of the state, and individual households it's something like 0.02% ... so really it's like comparing an ounce of piss to the ocean.

Alfalfa farms (of which the governor is an alfalfa farmer) are the worse culprits as it's a water heavy plant, and we're also a top exporter of alfalfa to Asia, so essentially Asia's buying our water from us via alfalfa.. there's plenty of other corporate/industrial culprits, but farms are a huge one here..