Scientific Investigations Report 2005-5102

Characterization of Surface-Water Quality in the S-Line Canal and Potential Geochemical Reactions from Storage of Surface Water in the Basalt Aquifer near Fallon, Nevada

By Alan H. Welch, Douglas K. Maurer, Michael S. Lico, and John K. McCormack

Report availability: Portable Document Format (PDF).

CONTENTS

Abstract

Introduction

Purpose and Scope

Acknowledgments

Methods Used

Water Sampling Methods

Geochemical and Mineralogic Analytical Methods

Physical Setting

Hydrogeologic Setting

• Recent Geologic History
• Description of Aquifers

Chemistry and Mineralogy of the Basalt Aquifer

Characterization of Surface Water in the S-Line Canal

Geochemical Modeling of Recharge

Modeling Approach

Model Scenarios and Limitations

Model Results

Summary and Conclusions

References Cited

Appendixes

FIGURES

1. Map showing geographic features of Carson Desert hydrographic area and Carson River basin
2. Map showing geographic features of Lahontan Valley and location of irrigated land, phreatophytes, and discharging playas
3. Map showing lateral extent of basalt aquifer and location of wells drilled into basalt aquifer
4. Oblique view of basalt aquifer, looking toward northeast
5. Photograph showing scoriaceous cinders near the top of Rattlesnake Hill
6. Photograph showing vesicular basalt flows on the southern flank of Rattlesnake Hill
7. Photograph showing fractured, vesicular basalt from well DB-1 recovered from a depth of 441-442 ft below land surface
8. Optical microscope micrograph of Type 1 basalt from well DB-1 at 545 ft with crossed polarizers and uncrossed polarizers
9. Optical microscope micrograph of Type 2 basalt from well DB-1 at 441 ft with crossed polarizers and uncrossed polarizers
10. Scanning electron microscope micrograph of vug-filling material from well DB-1 at a depth of 625 ft showing phillipsite
11. Scanning electron microscope micrograph of vug-filling material from well B-7 at a depth of 72 ft showing dolomite rhomboids above phillipsite rhomboids and phillipsite prisms on surface of adularia
12. Graph showing arsenic and dissolved organic carbon concentrations in S-Line Canal and mean daily flow in the Carson River below Lahontan Reservoir
13. Graphs showing results of geochemical simulation of injection well model of recharge into the basalt aquifer
14. Graphs showing results of geochemical simulation of basin-infiltration model of recharge into the basalt aquifer

TABLES

1. Bulk chemical composition of the basalt aquifer encountered at test hole DB-1
2. Concentration of elements released from basalt rock samples following:
   1. Cation exchange using ammonium chloride
   2. Anion exchange using potassium nitrate
   3. Extraction of carbonate minerals by sodium acetate and acetic acid
   4. Extraction of iron and manganese oxides by hydroxylamine hydrochloride and acetic acid
3. Mean bulk density and porosity of basalt samples
4. Surface complexation constants for carbonate adsorption on ferrihydrite
5. Initial conditions and reactions used for geochemical modeling of injection and infiltration of surface water and its subsequent recovery

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