Version History for DS 548 Jeannette H. Oden, Timothy D. Oden, and Zoltan Szabo Groundwater Quality of the Gulf Coast Aquifer System, Houston, Texas, 2007–08 ----------------------------------------------------- Version 1.0: Posted On-line December 17, 2010 ----------------------------------------------------- Version 1.1: Posted On-line July 7, 2011 Page 14, Second column, first complete paragraph, seventh sentence. Replaced thallium with thorium.