The wizard casting a lower water spell causes water or similar fluid in the area of effect to sink away. The
water can be lowered up to 2 feet for every experience level of the wizard, to a
minimum depth of 1 inch. The water is lowered within a square area whose sides
are 10 feet long per caster level. Thus, a 12th-level wizard affects a volume
of 24 feet x 120 feet x 120 feet, a 13th-level caster a volume of 26 feet x 130
feet x 130 feet, and so on. In extremely large and deep bodies of water, such
as deep ocean, the spell creates a whirlpool that sweeps ships and similar
craft downward, putting them at risk and rendering them unable to leave by normal
movement for the duration of the spell. When cast on water elementals and other
water-based creatures, this spell acts as a slow spell: The creature moves at half speed and makes half the number of attacks
each round. It has no effect on other creatures.

The material component of this spell is a small vial of dust.

Its reverse, raise water, causes water or similar fluids to return to their highest natural level:
spring flood, high tide, etc. This can make fords impassable, float grounded ships,
and may even sweep away bridges, at the DM’s option. It negates lower water and vice versa.

The material component of the raise water spell is a small vial of water.