n large aquatic elemental water 

Perception +18; darkvision

Languages Aquan

Skills Athletics +20, Stealth +19

Str +5 Dex +5 Con +5 Int -1 Wis +3 Cha +0

Water-Bound When not touching water, the living waterfall is slowed 1 and can't use reactions.

AC  28; Fort +18, Ref +21, Will +15

HP 155; Immunities bleed, poison, paralyzed, sleep; Resistances fire 10

Vortex (aura, water) 30 feet. Water in the area that is in the same body of water as the living waterfall is difficult terrain for Swimming creatures that don't have the water trait.

Speed 30 feet, swim 80 feet

Melee [>] wave +21 (reach 15 feet), Damage 2d12+11 bludgeoning plus Push or Pull 10 feet

Drench [>] (abjuration, primal, water) The elemental puts out all fires in a 10-foot emanation. It extinguishes all non-magical fires automatically and attempts to counteract magical fires (+20 counteract modifier).

Bestiary, page 153. Expanded in LOIL.