Richard L. Marella 1998 Nearly 800 million gallons per day of treated wastewater was discharged in the Southern Florida National Water-Quality Assessment (NAWQA) study unit in 1990, most to the Atlantic Ocean (44 percent) and to deep, saline aquifers (25 percent). About 9 percent was discharged to fresh surface waters and about 22 percent to shallow ground water, of which septic tanks accounted for 9 percent. Runoff from agricultural and urban lands, though not directly measured, is a large source of wastewater in southern Florida. application/pdf 10.3133/fs03298 en Geological Survey (U.S.) Water-Quality Assessment of Southern Florida - Wastewater Discharges and Runoff reports