Protecting our water resources
Turning on a faucet to get a drink of water, to take a shower or to wash clothes is something many people in Florida do without thinking. Since the time when indoor plumbing became commonplace, individuals, industries and utilities supplying water to the public have drilled holes into the underground water source, called an aquifer, to pump freshwater to the earth’s surface for a variety of uses. About 90 percent of us in north and east-central Florida get our water supply from an aquifer.
What is an aquifer?
Aquifers can be thought of as vast under-ground, sponge-like rocks that hold water and allow water to move through the holes within the rock. Aquifers are layers within limestone and sand shell rock under the earth’s crust. Fresh and salt water fill the various sized holes in the rock.
In some areas, an aquifer is kept in place by a thick layer of clay and then by more sandy soil up to the land’s surface. Where an aquifer is held tightly underground, or confined, the water is under pressure. The pressure allows water to rise through a well in the aquifer above the land without pumping, such as in an artesian well. The largest aquifer in the south-eastern United States is the Floridan.
How does water reach an aquifer?
Aquifers are filled, or recharged, by rainfall. On average, Florida receives 50 inches of rain each year. However, not all the rain reaches the aquifer. About 37" evaporates or runs off the land into surface waters before it has a chance to soak into the ground. This leaves 13 inches annually to recharge the aquifer.
Scientists say the water in the Floridan aquifer is 50 to 26,000 years old. The age of the water varies because of the time it takes water to seep through different types of soil. Sandy soils are most suited to allowing water to seep into the ground, while soils such as clay are more difficult to penetrate. Water’s downward movement is measured in inches per year and horizontally in feet per year.
Why does water quality vary?
In some areas, water in the Floridan aquifer is not suitable to drink without treatment because it contains various minerals or salts.
Saltwater, which is heavier than freshwater, can seep into drinking water wells, known as saltwater intrusion, making the water too salty to drink. Though saltwater is present every-where in the aquifer deep below the fresh-water, saltwater intrusion occurs when wells are drilled too deep or when too much fresh-water is pumped from the aquifer, allowing saltwater to replace freshwater.
Besides drinking, what are some other uses for water from aquifers?
Besides supplying drinking water, recreational opportunities are found for the water that escapes from aquifers in Florida. Where the aquifer’s waters escape their deep holding place, known as springs, millions of Florida residents and tourists alike don scuba gear, snorkeling gear, or look through glass bottom boats when they visit attractions such as Silver Springs in Marion County. Springs from the aquifer system also are found in the Atlantic Ocean, lakes and rivers.
What threatens the aquifer system?
The aquifer system is threatened daily because less and less area is available to allow rainfall to refill the aquifer system. This is due to paving of parking lots, roads, shopping centers, housing developments, and other buildings covering lands that have soils best suited for allowing water to seep into the aquifer. Various pollutants that run off of developed areas and seep into the ground also threaten aquifer water quality.
Will there be water from aquifers for the future?
Though there appears to be a vast supply of water today in the aquifer system, we must maintain a balance with nature to ensure plentiful supplies for the future. On one side, man draws water out of aquifers for drinking and for agricultural and industrial uses. The rain that fills aquifers is also needed in lakes, rivers, estuaries, and wetlands to meet nature’s needs.
To help maintain a balance among its many duties, the St. John’s River Water Management District (SJRWMD) works daily to review applications for large uses of water. The SJRWMD also works to educate the public on ways to conserve water, and to protect, restore, and enhance water bodies for the wildlife and people who use them.
What are some other water resources?
One of the ways to make sure that high-quality drinking water is available in an aquifer when needed, is for people to lessen their dependence on groundwater. Alternative water resources include using reclaimed water, by removing salt from brackish (slightly salty) surface water, and through the desalination of salt water.
What are some facts about aquifers?
- The largest aquifer in the southeastern United States is the Floridan. The Floridan aquifer is found beneath all of Florida, and portions of Alabama, Georgia, and South Carolina. It extends into the Gulf of Mexico, the Atlantic Ocean and the Caribbean Sea.
- The Floridan aquifer averages 1,000 feet in thickness, and freshwater can extend to a depth of 2,000 feet below the land surface.
- In some areas of central Florida, the Floridan aquifer can be found at land surface. The aquifer is found closer to the surface in the west coastal and north-central Florida areas.
- The top of the Floridan aquifer resembles an arc, closer to the earth’s surface in central Florida and deeper in the northern and southeast portions of the state.
- In general, the water that comes from deeper aquifers is considered better than the water that comes from shallow aquifers because deeper aquifers are less susceptible to contamination.