Reanalysis of the Medina/Diversion Lake System Water-Budget, with Estimated Recharge to Edwards Aquifer, San Antonio Area, Texas

Hydrologic water-budgets were calculated for the Medina and Diversion Lake system near San Antonio, Texas for periods between March 1955 and June 2002. The hydrologic-budgets were calculated from daily hydrologic data that included precipitation, evaporation, streamflow, and change in reservoir storage. The residual of the hydrologic budgets represent ground-water outflow from the Medina and Diversion Lake system to the Edwards aquifer. The ground-water outflow, sample size, standard deviation, and average Medina Lake stage, were computed from 127 water-budget periods ranging from 8 to 78 days from daily hydrologic data collected during March 1955-September 1964, October 1995-September 1996, and February 2001-June 2002.