In Sin City, one thing that will soon become unforgivable is useless grass. A new Nevada law will outlaw about 31% of the grass in the Las Vegas area in an effort to conserve water amid a drought that’s drying up the region’s primary water source: the Colorado River. Other cities and states around the U.S. have enacted temporary bans on lawns that must be watered, but legislation signed Friday by Gov. Steve Sisolak makes Nevada the first in the nation to enact a permanent ban on certain categories of grass.