When most Americans think of U.S. dairy, they picture cows roaming on the verdant pastures of Wisconsin. But in reality, they should replace that image with the tawny fields of California, the largest dairy producing state.

California produces more milk and cheese than anywhere else, including Wisconsin, the second biggest producer. California is in the middle of a megadrought, and dairy cows need loads of water. Some of that water is for the animals to drink and wash, but most of the water consumed by dairy is connected to what cows eat, in the form of feed and forage.

Much of the region is situated in arid or semi-arid lands, and with the effects of climate change it’s becoming drier and more susceptible to deep drought. The U.S. Southwest’s 22-year megadrought has been determined the driest in 1,200 years, and is contributing to the water crisis in the Colorado River Basin. With California the biggest agricultural producer in the arid West, it’s essential to understand what’s grown and fed to dairy cattle there, and the water required to grow that feed.