This Is How Much Water California Needs to Recover From Its Drought

California needs about 11 trillion gallons of water to recover from its three-year drought, according to a new NASA analysis, providing the first-ever calculation of this kind.

The figure, equivalent to about 1.5 times the maximum volume of the biggest U.S. reservoir, was determined by using NASA climate satellites to measure the water storage in the region’s river basins, which is one index for measuring drought severity, the agency said in a statement released Tuesday. The data reveals that since 2011, the Sacramento and San Joaquin river basins decreased by 4 trillion gallons of water each year — more water than the state’s 38 million residents use annually.

Scientists said that while recent storms in California have helped the state replenish its water supply, a full recovery will take much longer. “It takes years to get into a drought of this severity,” said Jay Famiglietti of NASA’s Jet Propulsion Laboratory, “and it will likely take many more big storms, and years, to crawl out of it.”