The Tohono O'odham Indian Reservation is a sprawling, sparsely populated stretch of desert and mountains along the Arizona-Mexico border. Immigrant and drug smugglers have long gravitated to the nation because of its remote location, prompting the Border Patrol to step up patrols and enforcement. Migrants often get lost or abandoned in the desert and die. The tribe's leaders won't allow humanitarian workers to come on to the reservation to leave water, largely because they are afraid leaving water will also aid drug traffickers. But at least one member of the reservation, Mike Wilson, has been ignoring criticism and leaving water for years.