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The water that flows from your faucets comes from an aquifer.
In fact, more than 90% of us in north and east-central Florida get our
water supply from an aquifer.
Aquifers are layers of rock,
gravel, shell, and sand — separately or in combinations — that hold water.
Florida’s main aquifer, the Floridan, begins in South Carolina and lies under
parts of Georgia, Alabama, and all of Florida.
As you travel south in Florida,
the Floridan
aquifer changes.
It gets saltier and is no longer used as a source of drinking water.
However, other water-bearing aquifers lie over the top of the Floridan. These aquifers
become the main source of drinking water
for many Floridians and most of south Florida.
Florida’s aquifer systems were developed as the land mass of Florida was created by
geologic forces.
According to the tectonic theory of continental drift,
the North American and African continents collided more than 300 million years
ago.
At that time,
a piece of the African continent became attached to North America
beneath what was then the Atlantic Ocean.
As millions of years passed, billions of sea creatures died and were deposited on the sea floor.
Some of these creatures eventually hardened
and created the bulk of Florida’s
limestone — now the rocks that comprise the Floridan aquifer.
Approximately 30 million years ago,
another geological force began to
create a cap on the Floridan aquifer.
The earth beneath the Appalachian Mountains to the north of Florida began to push the mountains upward.
The building of mountains caused
a great deal of erosion.
The sand, clay, and silts were transported south and deposited over the limestone of the Floridan
aquifer.
This cap now acts as a confining unit.
It can prevent water from flowing up to the surface, or it may
prevent contaminants from reaching down to the Floridan aquifer. Cycles of glaciers
growing and shrinking as the earth cooled and warmed caused the sea level to fluctuate
as much as 400 feet.
At the low sea levels, sediments stopped being deposited on the surface.
On the current land surface, Florida's old shorelines can be seen, shaped like stair steps.
Some of Florida's many layers are made up of
course sand. Some are very fine sand, clay, and silt.
In some areas, these particles have solidified over time into hard rock.
Most of these layers allow water
to move freely through them. In some underground areas, the water
moving through the aquifer has
eroded the rock layers to form caves and caverns. Theses caves and caverns
became free-flowing water highways we call spring systems.
These various layers of the geological sandwich we call Florida make up our aquifer system.
Most of Florida gets an average
of 54 inches of rain each year.
In some areas of Florida,
the geology allows that rain to seep down into
the aquifer. This process of replenishing the water in our aquifers is
called aquifer recharge.
In other areas,
very little of the rain that falls
seeps into the aquifer.
Most of it drains off
the earth’s surface into lakes,
rivers, the gulf of Mexico,
and the Atlantic Ocean.
Because Florida is a peninsula, a land mass surrounded by water on three sides, the Floridan aquifer
faces a unique situation. The aquifer is threatened by saltwater intrusion along all
of its coastline and from underneath.
Ancient sea water heavier than the freshwater we depend on
lies at the bottom of the aquifers. When we withdraw too much freshwater from a well, we start
to pull up the heavier salt water.
This is called vertical saltwater intrusion.
If we draw too much water from our wells near the coasts, salt water from the ocean can be pulled
in.
This is called
horizontal saltwater intrusion.
Most of our coastal communities must now pipe their water from wells far inland,
because salt water is intruding into our aquifers
along the coasts.
The main things we can all do
to help protect our precious aquifers
is to practice conservation
and make sure we use water wisely.
As you can see,
Florida’s aquifer systems are the foundation of our quality of life
and the healthy economy under which prosper.
This fragile resource must be managed with care,
to ensure the continuing health of all that we have come to enjoy and love
about this special place called Florida.