Ground water from deep wells
(500 to 1,000 feet deep) is warmed
by the internal heat of the earth
and may be suitable for use in
channel catfish hatcheries without
temperature modification. Water
from shallow wells (less than 300
feet) and some surface waters are
too cool to use directly. Cool
ground waters can be impounded
in a small reservoir pond where
solar heating will raise the temperature
to some extent.