Rob McMillan traveled to the Colorado River to track where the water is going. His journey begins at Lake Mead, Nevada.
Lake Mead is the largest reservoir in the United States and a critical source of water for Nevada, Arizona and California. But right now, it's at only about 25 percent of total capacity.
Even though the lake level has gone up a little bit in recent weeks, it's still very near its historic low set earlier this summer.
"You're talking about the water supply for 27 million Americans," said John Entsminger, general manager of the Southern Nevada Water Authority.
The Southern Nevada Water Authority gets 90 percent of its water from Lake Mead.
"Thankfully for Las Vegas, we're upstream of Hoover Dam, so we have engineering solutions that people downstream of us don't have, but it's impossible to look at Lake Mead and not be very concerned," Entsminger said.
It's all part of the Colorado River, which starts east of the Rocky Mountains. From there, it flows southwest into Lake Powell, through the Grand Canyon, and into Lake Mead. Then it's past Hoover Dam, where the river becomes the dividing line between California and Arizona, providing a critical supply of water for both states. So who gets what?
Well, seven states take water from the Colorado River, and the largest allotment on the river goes to California.
"The most important asset that Metropolitan has is its water right from the Colorado River; it's priceless. You couldn't buy one today with all the money in the world," said Bill Hasencamp from Metropolitan Water District of Southern California.
Hasencamp is the Colorado River resources manager for Metropolitan Water District. While MWD gets a sizable portion of water from the state water project, in drought conditions, we get most of our water from the Colorado River.
The Imperial County farmers
But the amount of water MWD gets from the Colorado River pales in comparison to what the Imperial Irrigation District gets in Imperial County - home to nearly half a million acres of farmland stretching from the Salton Sea all the way to the Mexican border.
"They're the largest water user in the entire basin," Hasencamp said.
Compared with the rest of Southern California, there aren't too many people who live in Imperial County, only 180,000. That's actually smaller than the city of Glendale. But this county does use a lot of water. The state of California's yearly allotment from the Colorado River is 4.4 million acre feet, and about two-thirds of that stays in Imperial County, with 97% of it used for farming.
Alex Cardenas, vice president of Imperial Irrigation District, says farmers have been working the Imperial Valley for more than a century, and they have some of the most senior water rights on the entire river. Now, given the severe drought, many wonder whether this multi-billion-dollar farming industry is sustainable.
"We're being told right now foraged crops is not a beneficial use of water. That is absolutely disturbing to hear. Cattle and dairy, and how critical those commodities are to our market," Cardenas said.
Cardenas makes the argument that while the population in L.A., Las Vegas and Phoenix has exploded over the past 75 years, Imperial County's farming acreage has stayed pretty much the same.
"We have been operating within those boundaries, so if you look at where this water is going, where's the demand, you really have to look at urban thirst," he said.
But customers in Southern California and Southern Nevada have cut back per-capita water use tremendously.
"We've added 750,000 people to our population since 2002, and in that same time period, we've reduced our use of Colorado River water by 26 percent," said Entsminger.
For example, all non-functional turf, like the grass along the main road through the Southern Highlands community in Las Vegas, will have to be ripped out by year 2026.
Residents like Dave Quick think some of the cuts have gone too far.
"Now they've regulated the size of a pool that can be put in to your house? How can they do that, this is America, this is not Russia," he said.
But as the water level at Lake Mead continues to drop, the urgency of finding some kind of solution is quite clear.
"It's going to continue to go down unless we get massive snowstorms, which we've only seen four times since the turn of the century, or unless we stop releasing water from the dam," Entsminger said.
It's a doomsday scenario, which would have dire consequences for tens of millions of people.