Acid Swamp

This spell transforms an area of a normal body of water into a pool of thick bubbling acid, blackish and opaque, that smells of sulfur. Creatures and objects splashed by the acid take 1d6 points of acid damage. If a creature is fully submerged at the start of it's turn (or an object at the start of your turn), it takes 10d6 acid damage; If it is partially submerged, it takes 5d6 acid damage. The toxic fumes forces any creature within 15 feet of the acid pool to make a successful Constitution saving throw, or take 2d4 poison damage and become poisoned until the start of it's next turn.

If this spell is cast on a body of running water such as a river, the spell lasts only 1 minute before the acid is washed downstream and diffused.