AN INVENTORY AND ASSESSMENT OF SPRINGS IN BIG BEND RANCH STATE PARK, TEXAS

The scarcity of water in arid desert environments, such as Big Bend Ranch State Park (BBRSP), Texas, make it a valuable resource for wildlife and visitors alike. This study is designed to organize and combine multiple datasets containing spring locations in BBRSP, in order to build a georeferenced GIS database of the known springs. The springs have been characterized based on general water quality, emergence type, rock or sediment in the area, wetted area, vegetation, anthropogenic impact, and evidence of use by wildlife and domesticated livestock. These parameters will be included in the attribute table of a shapefile built using ArcMap (ESRI) as part of the GIS database. It is our intention that this information can be used by park officials, visitors, and researchers both academically and recreationally.

Additionally, a subset of the springs has been analyzed for major cation and anion concentrations to ascertain rock/water interaction. This allows the modeling of the compositional evolution of the water from precipitation to spring emergence. The generally low total dissolved solids (TDS; 230 to 660 mg/L) of the springs suggest shallow, minor, perched aquifers isolated by aquitards in the volcanic stratigraphy from deeper circulation and the underlying Cretaceous and older carbonates. These aquifers and related flow paths are largely in mafic to silicic igneous rock related to the Trans-Pecos Magmatic Province, which was active 48-17 Ma. Flow paths are associated primarily with the permeable members of the Rawls, Fresno, and Closed canyon formations. Additional flow is associated with the numerous fault planes that occur in the park, related to Basin and Range and Rio Grande Rift extension.