Control water Control water , also known as lower water and its reverse , raise water , was a transmutation / alteration spell that allowed the caster to gain some control over a body of water . Effects . The older versions of this spell reduced or increased the water level of a cistern , stream , river , pond , lake , or other body of water . The area of effect was a square at least 70 ft ( 21 . 3 m ) on a side , or even bigger for more experienced spellcasters . One version allowed the caster to double one dimension and halve the other . The oldest versions of this spell took 10 minutes to cast and lasted 5 minutes per level of the caster . The next version lasted twice as long and took only a few seconds to cast . If the caster chose " lower water " , the surface dropped at least 14 ft ( 4 . 3 m ) or more , but was limited to a minimum depth of 1 in ( 2 . 5 cm ) . If the target body of water was very large and deep compared to the area of this spell , a whirlpool was created that could trap vessels for the duration of the spell and possibly swamp or sink them . If cast upon a water elemental or a similar water - based creature , it acted as a " slow " spell on that creature . If the caster chose " raise water " , the surface rose to either the highest naturally occurring level ( high tide or a typical yearly maximum flood stage ) or uplifted a volume of water similar in size and shape to the " lower water " version . Vessels lifted in this manner slid down one side of the watery hump as gravity dictated . The post - Second Sundering version could effect a cube of up to 100 ft ( 30 m ) on a side and would last for up to 10 minutes as long as the caster maintained concentration on the spell . The caster could chose between " flood " , " part water " , " redirect flow " , and " whirlpool " effects . " Flood " would raise still water about 20 ft ( 6 . 1 m ) . If placed in a large body of water , it would create a 20 ft ( 6 . 1 m ) wave that traveled from one side of the area to the other before crashing , and repeat this every couple of seconds unless another effect was chosen or until the spell ended . These waves would carry smaller vessels away or batter larger vessels as if they were in a stormy sea . " Part water " would make a trough of air from one end of the area of effect to the other , piling up the water to form walls on either side . The passage remained for the duration of the spell or another effect was chosen , whichever came first . " Redirect flow " would make already flowing water alter course to a path chosen by the caster . The path could be over obstacles , up walls , across ceilings , through openings , " etc . " If the water moved outside the area of effect , then normal water movement immediately resumed at that point . " Whirlpool " only functioned if the volume of water was at least 50 ft ( 15 . 2 m ) square and 25 ft ( 7 . 6 m ) deep . The spell would form a vortex 25 ft ( 7 . 6 m ) deep , 5 ft ( 1 . 5 m ) across the base and up to 50 ft ( 15 . 2 m ) across the top . Anything floating or swimming in the water within 25 ft ( 7 . 6 m ) of the edge of the vortex was drawn toward it . Creatures could swim away if they were strong enough , but once caught in the vortex they were pummeled repeatedly until they managed to escape or the spell ended . Components . All versions needed vocal and somatic components . The oldest versions needed a vial of water for " raise water " or a vial of dust for " lower water " . Later versions reduced the material component to just a drop of water or a pinch of dust . The post - Second Sundering version needed both water and dust to cast .