An investigation of the hydrogeochemistry and sources of salinity in the Dolores River watershed, southwestern Colorado
In part due to the dissolution of the halite- bearing Pennsylvanian Paradox Formation and sulfates associated with the Cretaceous Mancos Shale Formation, salinity issues in the Upper Colorado River water basin are known and well-studied. The Dolores River, in southwestern Colorado, is particularly well studied at Paradox Valley. Previous studies have usually only analyzed the hydrogeochemistry at one or two locations along the Dolores River. In this study, measurements of major ions and stable sulfur isotopes (δ34Sso4) of water samples from five locations along the Dolores River were used to investigate the water type. Shifts in water type and isotopic composition of sulfur indicate the source of sulfate changes at Big Gypsum Valley. This study adds more detail to the geochemical evolution of salinity sources along the Dolores River which provide insight to determining if increased precipitation, irrigation, or other natural and anthropogenic activities could impact Dolores River salinity.
Faculty Mentor: Gary Gianniny