"At a place called Lorca, in the eastern part [of Spain], runs a river called the Salty Brook. Be careful not to let it touch your lips or allow your horse to drink there, for this river is deadly," warns the 12th-century author of The Pilgrimís Guide to Santiago de Compostela. "On its bank, while we were going to Santiago, we met two men of Navarre sitting sharpening their knives; they are in the habit of skinning the mounts of pilgrims who drink that water and die. When questioned by us, these liars said that it was safe to drink.