From afar, the rows of knobby grapevines blend into the landscape of pink-blossomed almond trees and fragrant citrus. But get up close and you’ll see something strange: The trunks of the vines are standing in several inches of glistening, precious water.

These grapes, at the Kearney Agricultural Research Center in California’s San Joaquin Valley, are part of a grand experiment that many hope will help solve the state’s deepening water crisis.