Final answer:
Lake Mead is the primary source of water for Las Vegas, providing about 90 percent of its supply. Reservoir levels are decreasing due to drought and high demand, requiring conservation efforts like increased water pricing and lawn removal incentives. Sediment accumulation in the lake is another issue threatening the long-term water supply.
Step-by-step explanation:
Lake Mead plays a crucial role in the water supply and usage for Las Vegas. The lake, which is a reservoir formed by the Hoover Dam, provides approximately 90 percent of the water for the city. This water originates as snowmelt in the Rocky Mountains and travels via the Colorado River to Lake Mead.
Due to ongoing drought and consistently high water demand in the arid climate of Nevada, Lake Mead's water levels have been declining. To combat potential water crises, Las Vegas has enacted water conservation measures such as increasing water prices and providing incentives to remove grass lawns.