Even the biggest reservoir in the US wouldn't provide enough water to replace what's been lost in California's drought. In fact, you'd need 1.5 times that much water, or 11 trillion gallons, to do so, according to NASA satellite findings. Another way to put it in perspective: It's 130,000 Rose Bowls' worth of water, USA Today notes. It's also more water than California uses every year, even with 38 million residents. This is the first time the amount of water needed to end a drought has ever been calculated, NASA reports. The study involved two satellites tracking the planet's gravitational field; small changes in the field are associated with changes in the water supply, Mashable reports.
Each year since 2011, the Sacramento and San Joaquin river basins have lost about 4 trillion gallons. What's more, the snowpack in the Sierra Nevada mountains is just half of what earlier estimates suggested, and it's "one of the three lowest on record and the worst since 1977, when California's population was half what it is now," a researcher says. That means less snow melt and more absorption of sunlight into the ground, helping warm the planet and leading to drier conditions that make it more difficult to get snow water to reservoirs, he adds. "It takes years to get into a drought of this severity, and it will likely take many more big storms, and years, to crawl out of it," says the water study's leader.