Florida’s Aquifer: The Treasure Below

Florida’s Aquifer: The Treasure Below


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 we 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.

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