Mammoth Spring State Park, Arkansas
WHAT
IS A FIRST
MAGNITUDE
SPRING?
Springs are often classified by the volume of
the water they discharge. The largest springs
are called "first-magnitude", defined as
springs that discharge water at a rate
of at least 740 gallons or 100 cubic
feet (2.8 m
3
) of water per
second.
Mammoth Spring is part of a large underground river system.
It's called a first magnitude karst spring and it starts with rain
falling in southern Missouri. It is the largest spring
in Arkansas and the third-largest spring in the
Ozark region behind Big Spring and Greer
Spring. Mammoth Spring is the seventh-
largest natural spring in the world.
The rain falls in Missouri and
seeps into the water table. Then
the water flows through a system
of passages and cavities. These
cavities make an underground
river that comes back to the
surface at the town of Mammoth
Spring, Arkansas.
The emerging water forms a 10-acre spring pool that drains over
a high stone dam. The spring generates about 10 million
gallons of water per hour and the temperature is
a constant 58 °F.
You can't see the water at the
Mammoth Spring because the mouth
of the river is more than 70 feet
below the surface of the large
spring pool.
You can see part of the
underground river that feeds
Mammoth Spring nine miles
northwest of Mammoth Spring
at a collapsed cave in Grand Gulf
State Park in Missouri. The remains
By Renee Durham • Official Kids Mag
44 • Of f icialKidsMag.com • FEBRUARY 2020
