US_Aquifers_USDOI

This layer contains the major underground aquifers found in Texas. This polygon file was designed for medium to small scale thematic mapping and analysis.

            

              

                

                  

                    
                      The spatial data were obtained from the Texas Water Development Board (TWDB) and are current as of 2007. Attributes were modified to include only aquifer name, code, rock name and type, and area information. The coordinate system of this data is WGS 1984.
                    
                  
                  

                    
                    
                  
                  

                    
                      The areal extent of the aquifers, as shown in this map layer, represents
                    
                  
                  

                    
                      the area in which a named aquifer is the shallowest of the principal
                    
                  
                  

                    
                      aquifers. These aquifer areas are not necessarily the only areas in which
                    
                  
                  

                    
                      ground water can be withdrawn, for two reasons: 1) The aquifers shown may
                    
                  
                  

                    
                      have a larger areal extent than is represented here. The boundaries in
                    
                  
                  

                    
                      this map layer generally represent an interpretation of the surface
                    
                  
                  

                    
                      location (outcrop), or near-surface location (shallow subcrop) of the
                    
                  
                  

                    
                      uppermost principal aquifer for the area. An aquifer may extend beyond
                    
                  
                  

                    
                      the area shown, but be overlain by one or more other aquifers, and (or)
                    
                  
                  

                    
                      low-permeability material. 2) There may be areas of water-bearing
                    
                  
                  

                    
                      surficial material not shown in this map layer. Major alluvial aquifers
                    
                  
                  

                    
                      that occur along main watercourses are not shown. Significant
                    
                  
                  

                    
                      unconsolidated sand and gravel aquifers, that are not indicated in this
                    
                  
                  

                    
                      map layer but are important sources of water, may occur locally in
                    
                  
                  

                    
                      glaciated regions. The user of this map layer is advised that to get
                    
                  
                  

                    
                      complete information regarding areas that serve as sources of water, more
                    
                  
                  

                    
                      information about surficial aquifers needs to be obtained, particularly in
                    
                  
                  

                    
                      glaciated areas.
                    
                  
                  

                  

                    
                      This map layer was constructed by combining data created for or from the
                    
                  
                  

                    
                      regional GWA chapters. Minor aquifers that are important local sources of
                    
                  
                  

                    
                      water were mapped in some regions, so the regional maps in the GWA may
                    
                  
                  

                    
                      show more detail than this map layer. The data were reviewed, adjusted,
                    
                  
                  

                    
                      and published based on new information provided by national, State, and
                    
                  
                  

                    
                      local scientists. The juxtaposition of regionally mapped aquifers has led
                    
                  
                  

                    
                      to some instances where an aquifer outcrop or shallow subcrop is bounded
                    
                  
                  

                    
                      by a State line. This is a result of the regional mapping and national
                    
                  
                  

                    
                      categorization methods used and is not meant to imply a hydrogeologic
                    
                  
                  

                    
                      change coincident with a State boundary.
                    
                  
                  

                    
                  
                  

                
              
            
          

Center for Geospatial Technology, Texas Tech University
US Department of the Interior

There are no access and use limitations for this item.