Background: Arsenic (As) concentration in groundwater varies across space and time Ingesting concentration above 10 ug/L can lead to kidney disease, skin cancer, or death (Smith et. al, 2002) As levels in the Panhandle and Gulf Coastal Plain areas are markedly higher than average statewide levels Landscape modification due to agriculture, energy extraction, and weathering influence spatial distribution of As Existing studies do not address regional analyses of As concentrations over space and time in Texas