Cannabis cultivation is emerging as an issue in the American West's interminable conflicts over control of water. On May 20, the US Bureau of Reclamation (BuRec), which supplies irrigation districts across the western states, issued a policy memo saying its water may not be used for marijuana. BuRec staff would document "all activities and communications" regarding "known or potential uses" of its waters for cannabis cultivation—and "will report such use to the Department of Justice." Washington state's Roza Irrigation District, which supplies BuRec water to some 72,000 acres in Yakima and Benton counties, in early April issued a "precautionary message" warning cannabis growers that they could get cut off. But the practical effects of the policy are unclear. If the Justice Department were to target irrigation districts for supplying water when it's not targeting the folks actually growing the cannabis, it would have a lot of angry corn and apple farmers on its hands.