Hydrogeochemical Inventory and Analysis of Thermal Springs in the Black Canyon-Hoover Dam Area, Nevada and Arizona

Abstract

An estimated 70 liters/sec. of spring flow discharges from both side of the Colorado River in Black Canyon, Nevada and Arizona. Observed springs issue primarily from the highly faulted and fractured volcanic rocks which are exposed throughout the canyon from Hoover Dam to 7.5 kilometers downstream. Chemical analyses of the spring waters, including stable isotope and tritium results, indicate a variety of possible origins and mixing scenarios. Observed surface temperatures range from 32 C to 62 C. Dissolved solid values range from 500 mg/l to 3600 mg/l. Tritium concentrations range from 10 T.U. to 116 T. U. While thermodynamic calculations indicated oversaturation of these waters with respect to several silicate and carbonate minerals, the general absence of secondary mineral deposits close to springs orifices suggests a potentially young system.