Geochemical and hydrologic data for San Marcos Springs recharge characterization near San Marcos, Texas, November 2008--December 2010

During 2008–10, the U.S. Geological Survey, in cooperation with the San Antonio Water System, collected geochemical and hydrologic data in Bexar, Comal, and Hays Counties, Texas, to define and characterize the sources of recharge to San Marcos Springs. Precipitation samples were collected for stable isotope analysis at 1 site and water-quality samples were collected at 7 springs, 21 wells, and 9 stream sites in the study area between November 2008 and December 2010. Continuous water-quality monitors were installed in three springs, two wells, and at one stream site. Three continuous stream-gaging stations were installed to measure gage height and a stagedischarge rating was developed at two of the three sites. Depth to water below land surface was continuously measured in two wells.