Effects of recharge from drainage wells on quality of water in the Floridan Aquifer in the Orlando area, central Florida

Approximately 400 drainage wells in the Orlando area inject, by gravity, large quantities of stormwater runoff that may or may not be suitable for most purposes without treatment into the same freshwater zones of the Floridan aquifer tapped for public supply. The wells are used mostly to control lake levels and dispose of urban storm runoff. Recharge from drainage wells compensates for heavy withdrawals from the Floridan aquifer and helps maintain aquifer pressures that retard upward saltwater encroachment. Sixty-five supply wells and 21 drainage wells within a 16-mile radius of Orlando were sampled from September 1977 to June 1979. Most constituent concentrations were slightly higher in water from drainage wells than in water from supply wells. The most notable differences were in bacteria colony count and total nitrogen concentrations. With the exception of bacteria, water from drainage wells would generally meet the maximum contaminant levels established by the National Interim Primary and Proposed Secondary Drinking Water Regulations. (USGS)