The deepening water shortage row between the US and Mexico

Will GrantMexico, Central America and Cuba CorrespondentBBCWater levels in Lake Toronto, a reservoir in the north of Mexico, are said to be critically lowAfter the thirtieth consecutive month without rain, the townsfolk of San Francisco de Conchos in the northern Mexican state of Chihuahua gather to plead for divine intervention.On the shores of Lake Toronto, the reservoir behind the state's most important dam –…