Each freshwater spring in Florida has its own springshed, an area of land near the spring that supplies water to that spring from surface water, groundwater and/or the Floridan Aquifer.
The Ichetucknee Springshed includes areas as far away as Baker County, Lake City and Alligator Lake, headwaters of the ancient Ichetucknee Trace (see Science). Water flows from these areas into Ichetucknee Springs from surface runoff in creeks and through swallets and sinkholes into the underground aquifer. Dye trace studies have shown that there are direct underground water routes between area sinkholes and the Ichetucknee Head Spring.
As water in the springshed makes its way to the springs, it picks up and carries pollutants that include nitrogen and phosphorous from fertilizers used on farms, ranches and lawns; waste from farm and domestic animals; human waste from septic tanks; pollutants from the air that have been deposited on the ground; and biosolids that are spread in rural areas after being treated by municipal sewage systems. All these pollutants eventually reach the springs, encouraging the growth of algae and damaging water quality.
For an excellent tutorial about problems existing in the springshed that affect the Ichetucknee, watch the video tour of the Ichetucknee Trace.
Water withdrawals within the springshed are also a concern because they can cause the level of the Floridan Aquifer to drop, leading to reduced spring flows. Average water withdrawals within the Ichetucknee Springshed have increased 132% since the 1960s, a time period that saw increasing population growth in Florida. Agriculture represents the highest estimated groundwater withdrawal (63%) followed by public/domestic supply (30%), industrial/commercial/recreational uses (6%). A tiny portion of pumped groundwater returns to the aquifer as recharge.
Scientific studies have revealed that groundwater pumping from as far away as Jacksonville/Duval County is siphoning water away from Ichetucknee Springs. The groundwater divide between Northeast Florida and North Florida has been moving slowly and steadily westward. Where groundwater used to flow west it now flows east, shrinking the size of the Ichetucknee Springshed.