California Farmers Used Enough Groundwater During Drought To Fill Lake Mead.
Amy Quinton / Capital Public Radio California farmers in the Central Valley pumped enough water out of the ground to fill Lake Mead, which can store the entire average flow of the Colorado River for two years.
It’s enough to drown the state of Pennsylvania in a foot of water.
The study also found the rate of groundwater withdrawal per year in the most recent drought was double that of the drought of 2007 to 2009, even though there was less land to irrigate.
“That sort of doubling of the extraction rate was attributable more or less in equal amounts to the fact that the recent drought was warmer and the evaporative amount was higher and the shift to row crops to tree crops,” says Dennis Lettenmaier with UCLA, the study’s lead author.
“Pumping groundwater during a drought is not an unreasonable strategy when there’s not enough surface water," says Lettenmaier.
"This is the big issue and there’s no real plan for putting that back in.” Laws to manage groundwater are being implemented in California.
Counties, irrigation districts, farmers and other entities must form agencies by the end of June that will be tasked with managing groundwater sustainably.
But limits on groundwater pumping won’t likely happen until after 2020.
Lettenmaier says the study shows that between droughts there was some groundwater replenishment.