UNLV Retrospective Theses & Dissertations 1-1-1989 Hydrogeology and ground-water quality in the Sanders area, western Puerco River basin, Arizona Earle Campbell Dixon University of Nevada, Las Vegas Follow this and additional works at: https://digitalscholarship.unlv.edu/rtds Repository Citation Dixon, Earle Campbell, "Hydrogeology and ground-water quality in the Sanders area, western Puerco River basin, Arizona" (1989). UNLV Retrospective Theses & Dissertations. 70. http://dx.doi.org/10.25669/cvc5-vjp4 This Thesis is protected by copyright and/or related rights. It has been brought to you by Digital Scholarship@UNLV with permission from the rights-holder(s). You are free to use this Thesis in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. 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University of Nevada, Las Vegas, 1990 UMI 300 N. Zeeb Rd. Ann Arbor, MI 48106 HYDROGEOLOGY AND GROUND-WATER QUALITY IN THE SANDERS AREA, WESTERN PUERCO RIVER BASIN, ARIZONA by Earle Campbell Dixon A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Geoscience Department of Geoscience University of Nevada, Las Vegas May, 1990 The thesis of Earle Campbell Dixon for the degree of Master of Science in Geosciences is approved. Chairperson, John W. Hess, Ph.D. Examining Committee Meplber, Steve A. Mizell, Ph.D. Exampiing Committee Menfber . Duebendorfer, Ph.D. Gra^dW^e Faculty f^pnisent^tive, Gary B. Palmer, Fh.D CJ Graduate Dean, Ronald W. Smith, Ph.D. University of Nevada, Las Vegas May 1990 ABSTRACT Ground-water in the western Puerco River basin near Sanders, Arizona, was evaluated to identify areas of poor water quality and possible radionuclide con­ tamination from natural and/or anthropogenic sources. In addition to docu­ mented radioactive occurrences in the regional Chinle Formation, the headwaters of the Puerco River have been host to uranium mine waste discharge and spoils from a tailings pond failure in 1979. Samples from 42 wells and springs were collected during 1987-88 for inorganic ion and radionuclide analysis. Waters, originating from the Alluvial, Bidahochi, and Chinle aquifers, contained variable amounts of dissolved solids and radioactivity. Dissolved solids content ranged from 105 to 1390 mg//, and combined gross alpha and beta activities ranged from 1 to 590 pCi//. In the Alluvial and the Chinle aquifers, major ion concentrations generally increased toward the river along the ground-water flow paths from NE to SW. Ground-waters samples were generally saturated with respect to calcite and quartz, but undersaturated with anhydrite, gypsum, and Si02. Trilinear diagrams defined mixed ion, Ca+Mg-HCO^-, and Na+K-HCCXf water-types. Data analysis and published literature suggested that cation-ion exchange of Na+ for Ca2+ and dissolution are important processes in water chemistry changes in the Alluvial and Chinle aquifers. Spearman rank correlation of selected chemical parameters to ion concentra­ tions and distance from sample location to the Puerco River, produced positive values, but few were large enough to suggest possible association. Significant correlation was observed for U and 226 Ra when paired with gross alpha and beta, TDS, HCO 3", and SO2-. Tritium analysis of 20 samples in the southeast part of the study area suggests that most ground water was more than 20 to 50 years old. Large spatial variations of 8 D and 8 180 in water samples suggest the ground-water system is complex and not easily explained with the small number of samples collected. However, regional radioactive occurrences and overall low correlation values suggested most elevated radioactivity in ground water was produced by natural sources and not by recharge water from the Puerco River. Table of Contents ABSTRACT ......................................................................... iii LIST OF FIGURES ............................................................................................. vi LIST OF TABLES................................................................................................ viii LIST OF ABBREVIATIONS ............................................................................. ix ACKNOWLEDGMENTS ...................................................................................... x INTRODUCTION ................................................................................................... 1 Purpose ........................................................................................................... 1 Objectives ....................................................................................................... 1 Historical Background .................................................................................. 2 Previous Works .............................................................................................. 7 METHODOLOGY................................................................................................... 10 Objective One ................................................................................................ 10 Objective Tw o ................................................................................................ 11 Objective Three .............................................................................................. 12 Ground-water Sampling .............................................................................. 12 Laboratory Analysis ..................................................................................... 16 Isotopic Analysis ........................................................................................... 16 Literature Review and Database ............................................................... 16 ENVIRONMENTAL SETTING ......................................................................... 18 Physiography ................................................................................................. 18 Climate ........................................................................................................... 20 Vegetation and Soils .................................................................................... 22 Puerco River Basin ........................................................................................ 24 Geology ........................................................................................................... 30 Stratigraphy ......................................................................................... 30 Structure ............................................................................................... 32 Geologic History .................................................................................. 32 Uranium Occurrence ........................................................................... 36 iv Hydrogeology ................................................................................................. 40 Occurrence of Ground Water .......................................................... 41 Hydrostratigraphy .............................................................................. 42 Ground-water Quality ....................................................................... 42 RESULTS AND DISCUSSION............................................................................. 48 Potentiometric Surface .................................................................................... 48 Ground-water Geochemistry