LOS ANGELES — The punishing drought that has swept much of the West is confronting authorities with the worst water shortage the region has faced in more than a century, with near-empty reservoirs, parched fields, starving livestock, clouds of smog, and outbreaks of wildfires.
With no sign of significant rain, 17 rural communities in California that provide water to 40,000 people are in danger of running out of water within 60 to 120 days.
California authorities announced Friday that they had no water left in the State Water Project, the main municipal water distribution system, to supplement the dwindling supplies of local agencies that serve 25 million people. It is the first time the project has turned off its spigot in its 54-year history.
“We are on track for having the worst drought in 500 years,” said B. Lynn Ingram, a professor of earth and planetary sciences at the University of California Berkeley.
State officials said that in the worst scenario, they would truck drinking water into parched communities and drill additional wells to draw on ground water.
The deteriorating situation is likely to mean imposition of mandatory water conservation measures for homeowners and businesses, who have already been asked to voluntarily reduce their water use by 20 percent.
The drought, technically in its third year, is forcing big shifts in behavior. Farmers in rural Nevada said they had even given up on planting, while ranchers in Northern California and New Mexico said they were being forced to sell off cattle as fields that should be 4 feet high in grass are blankets of brown and stunted stalks.
“I have experienced a really long career in this area, and my worry meter has never been this high,” said Tim Quinn, executive director of the Association of California Water Agencies, a statewide coalition. “We are talking historical drought conditions, no supplies of water in many parts of the state.