July 29, 2022

Master Naturalist Spotlight Series

Recharging the Floridan Aquifer: General Information

In the past twenty-five years, Florida’s population has increased by over forty five percent. Today, approximately 90% of Florida’s twenty-two million residents depend on Florida’s aquifer system for their drinking water.

Different types of aquifers exist below Florida’s surface. The largest of these is the Floridan aquifer and it consists of large underground zones of permeable rock (limestone), that was created over millions of years by the accumulated skeletal remains of fish, shellfish, and coral. In Duval County, the public utility, JEA pumps water directly from the Floridan aquifer to supply to its business and residential customers.

Aquifer Recharge

Florida’s exploding population draws approximately seven billion gallons of water each day, with most of this supplied by Florida’s various aquifers. Because of this enormous demand for water, it is critical for Florida’s health that the aquifers be refilled, or recharged. The recharging of Florida’s aquifers occurs primarily through rainfall. Most rainfall, however, is evaporated and will not return to the aquifer. To compound the challenge of aquifer recharge, the geology of Florida is such that many areas of Florida are not well-suited to recharge the aquifer because they sit atop rather impermeable layers of clay through which water cannot easily pass back into the aquifer.

Figure 2: Lake Brooklyn, photo by Stephanie Hezel

A primary aquifer recharge area in north Florida is found in Keystone Heights, in Clay County, where the geology under the sandy lake beds is primarily permeable limestone through which water can pass more easily to the aquifer system.

Over the past decade, the water level of recharge areas in Keystone Heights, such as Lake Brooklyn, has fallen drastically. Beginning in the summer of 2022, the St. Johns River Water Management District’s plan to restore water to Lake Brooklyn is set to commence when construction is started on a pipeline that will divert water from Black Creek in Middleburg to Alligator Creek, where it will then flow into Lake Brooklyn.

When completed, it is hoped that Lake Brooklyn will supply an added 4.5 million gallons per day to the aquifer.

It is imperative that natural aquifer recharge zones be preserved so they can continue to serve their vital function of refilling the aquifer.