The difference is that animals drinking water is part of the natural cycle, showers are not. There's essentially no difference between the water usage of cattle on unirrigated native prairie and the water usage of the bison that preceded them.
Of course, cattle in California isn't raised on unirrigated native prairie, like they are in Texas or Montana.
Lots of cattle are raised on grasslands in California, but not in the San Joaquin Valley, because that would be a waste of prime land. You can find grazing lands in Marin, Sonoma, San Benito, and other hilly counties.
Of course, cattle in California isn't raised on unirrigated native prairie, like they are in Texas or Montana.