Florida is the fifth-rainiest state in the U.S., receiving an annual average of about 150 billion gallons of rain per day. In the 1,400-square-mile area that feeds groundwater to Silver Springs, average rainfall supplies about 3.4 billion gallons per day. On average, only about 15 percent of this rain finds its way into the Floridan Aquifer.
In just the first two weeks of June, the Silver springshed received an estimated 200 billion gallons of rain. This rain resulted in a jump in groundwater levels throughout Alachua, Lake, Marion, Putnam and Sumter, the four counties that feed flow to Silver Springs and local water supply wells. The welcome rain soaked the parched earth, revitalizing pastures, lawns, crops, forests and wetlands. And this rain breathed additional life into our region’s most mighty spring, gasping from declining flows over the past 50 years.
Despite this natural bounty from the sky, north Florida continues its reliance on groundwater for irrigation of urban lawns and agricultural crops. Average flows at Silver Springs have progressively declined by more than 36 percent, from a pre-1970 average of about 520 million gallons per day to an average of 330 million gallons per day during the most recent decade. An estimated 120 million gallons per day of the flow reduction at Silver Springs is due to the net consumption of groundwater extracted through wells.
Studies conducted throughout Florida’s springs region indicate that any reduction in flow is harmful to a spring’s environmental health. Reduced flows result in lower aquatic plant production, decreased fish and wildlife populations, and less ability for a spring to clean itself of noxious algae and pollutants.
While zero flow reduction would be preferable for maintaining healthy springs, some groundwater is needed for agricultural and urban development. Due to an inter-dependence on groundwater resources, natural environments, especially springs, suffer as the human economy grows. If an acceptable balance between these competing aquifer uses is not achieved, then the combined health of humans and the environment is diminished as well.
Florida’s legislators anticipated this conflict with passage of the Water Resources Act of 1972. This law required the state’s five water management districts to adopt minimum flows for springs that would protect them from harm caused by competition for finite water supplies.
This year, the St. Johns River Water Management District finally adopted a minimum flow rule for Silver Springs. The rule is intended to preserve 94 percent of the natural flow at Silver Springs. But this goal is difficult for the public to assess since the district gauges compliance with a complex and imprecise groundwater flow model. This assessment would be improved by comparing the measured flows at Silver Springs to the minimum flow rule.
The actual data tell us that flows have been below the target minimum for 15 of the past 16 years. Analysis by the Florida Springs Institute finds that groundwater pumping in and around the Silver springshed needs to be reduced by more than 90 million gallons per day to comply with the district’s minimum flow target. Despite this deficit in actual flows at Silver Springs, the St. Johns district continues to issue new groundwater pumping permits.
Substantial spring flow reductions have also been recorded elsewhere in north Florida, with a 20 percent decline at Rainbow, more than 50 percent decline at Crystal River, and up to 40 percent or more throughout the more than 200 springs in the Santa Fe and Suwannee River drainages. The same type of model used by the St. Johns district is being used to establish “minimum flow” rules at these other springs. Unfortunately, all of these new rules authorize increased groundwater pumpin, and additional harm to the region’s springs.
The old proverb, “when it rains, it pours,” has more than one meaning. On one hand, it sums up recent weather in north Florida. Mother Nature has been more than generous showering her liquid bounty over the land.
But on the other hand, this phrase reminds us that misfortunes often follow each other in rapid succession. Almost without exception, our defenseless springs are being sacrificed on the altar of economic development. Minimum flow rules developed by the water management districts provide the appearance of protection without acknowledging the fact that our springs are already well beyond the point of significant harm.
Please raise your voice and speak for the springs by turning off your irrigation system. Install a rain barrel if you must water your plants and talk to your neighbors about using less groundwater. Hopefully, everyone will turn off their sprinklers to save our springs.
— Robert Knight is director of the Howard T. Odum Florida Springs Institute in High Springs.