All of us living in and visiting Florida have an “Aquifer Footprint.” Our Aquifer Footprint is measured by the amount of groundwater we use from the Floridan Aquifer and our contribution to the nitrate-nitrogen pollutant load to the aquifer. One’s Aquifer Footprint is an estimate of the personal detrimental impact we each place on Florida’s groundwater environment, especially the ecology of the State’s springs, rivers, lakes, and estuaries supported by that groundwater. Each person’s Aquifer Footprint can be a source of personal pride or an area for improvement.
If you live where the Floridan Aquifer is vulnerable to contamination due to a lack of impervious clayey soils, and you apply fertilizer to your lawn, garden, or pasture, you have an elevated nitrogen Aquifer Footprint. If your home’s wastewater is disposed of in a septic system and your lot is less than five acres, you also have an elevated nitrogen footprint. If you water your yard and landscaping plants with groundwater or consume unusually large volumes of water in your house, then you also have an elevated water use footprint.
The Howard T. Odum Florida Springs Institute has completed the first phase of the “Blue Water Audit”, an assessment of the Aquifer Footprint of the 4.2 million Floridians living in the Springs Region of North and Central Florida. Publicly-available geographic information system (GIS) databases were analyzed by overlaying information on land use, aquifer vulnerability, property ownership, method of wastewater disposal, human population, and other factors to estimate the effects of humans and their domesticated animals on the quantity and quality of the water in the underlying aquifer. If you live within an urban boundary, your estimated impact on the Floridan Aquifer is reported as an average with all your urban neighbors. If you own property covering five or more acres outside of an urban boundary, your Aquifer Footprint is reported individually for your property. The Blue Water Audit provides the first comprehensive estimate of individual human impacts to the Floridan Aquifer and the springs and other surface water bodies it supports.
For example, the Blue Water Audit estimates that about 22,000 tons of nitrate-nitrogen reach the Floridan Aquifer each year in Florida’s 15 million-acre Springs Region. An estimated one billion gallons per day of groundwater is pumped cumulatively by residents, municipalities, farmers, and industries in north-central Florida. The average per capita nitrogen load and groundwater use in this Springs Region is 10.6 pounds per year and 230 gallons per day, respectively. For Alachua County residents the per capita averages are 9.5 pounds per year of nitrogen loading and 142 gallons per day of groundwater use. By contrast, the Aquifer Footprint for an individual living in Suwannee County (i.e., highly vulnerable aquifer, intensive agriculture, and low human population compared to livestock population) is 84.5 pounds per year of nitrogen loading and 1,455 gallons of groundwater per day. A few counties have lower estimated Aquifer Footprints. For example, Leon County has a per capita nitrogen footprint of 5.1 pounds per year and a groundwater use footprint of 75.8 gallons per day per person. These lower numbers reflect a large urban population within a region of low agricultural productivity.
We all have an Aquifer Footprint. If you refrain from using fertilizer or irrigating your lawn, you are doing your part in protecting the aquifer and springs. There is little more that you can change in your life to directly save the springs. But if you are wasteful with fertilizer and water you can make personal choices that will significantly reduce your Aquifer Footprint.
Make no mistake, the Aquifer Footprint of a farmer irrigating and fertilizing 200 acres of vegetables or a dairyman keeping 2,000 milk cows, is more than one hundred times more impactful to the aquifer than a person living in an apartment or retirement village. A lush golf course or fancy corporate park with irrigation and landscaping may have an Aquifer Footprint equivalent to thousands of individuals. It is imperative for environmentally-damaging businesses and local governments to reduce their Aquifer Footprints. In pursuit of improved human health and environmental protection, the public interest should take precedence over personal gain or extravagant lifestyles.
The net result of the choices we are currently making in Florida’s Springs Region is an average groundwater nitrate-nitrogen concentration 2,900 percent higher than natural background concentrations and an overall decline in average spring flows of about 32 percent. One goal of the Blue Water Audit is to continue making these estimates over time to determine how much the state’s roughly $100 million annual springs protection expenditures are, or are not, improving conditions in the Floridan Aquifer and springs. So far, despite record funding, our springs and drinking water supply are becoming more depleted and polluted every year. Reducing your personal Aquifer Footprint is essential. But without government action, the springs and aquifer cannot be saved. Please keep that fact in mind when you cast your votes this year.
Dr. Bob Knight is Director of the Howard T. Odum Florida Springs Institute.