U.S. Department of the Interior
U.S. Geological Survey

Water Quality and Environmental Isotopic Analyses of Ground-Water Samples Collected from the Wasatch and Fort Union Formations in Areas of Coalbed Methane Development—Implications to Recharge and Ground-Water Flow, Eastern Powder River Basin, Wyoming

Water-Resources Investigations Report 02-4045
Cheyenne, Wyoming, 2002

Prepared in cooperation with the
WYOMING STATE ENGINEER'S OFFICE and the BUREAU OF LAND MANAGEMENT

By Timothy T. Bartos and Kathy Muller Ogle

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CONTENTS:

• Abstract
• Introduction
  • Purpose and scope
  • Numbering system for wells and springs
  • Methods of investigation
• Description of study area
  • Climate
  • Geographic and geologic setting
  • Hydrogeologic setting
  • Resource extraction
  • Acknowledgments
• Water-level measurements
• Ground-water quality
  • Quality assurance and quality control
  • Major-ion chemistry
    • Classification of ionic composition and comparisons between aquifers
    • Areal distribution
    • Vertical distribution within aquifers
    • Vertical distribution between aquifers
    • Geochemical processes
  • Environmental isotopes
    • Tritium
    • Stable isotopes of oxygen and hydrogen
• Hydrogeologic implications of observed major-ion chemistry and environmental isotopes
• Comparison of water quality to regulatory standards
  • Public supply and domestic use
  • Agricultural use
• Summary
• Selected references
• Appendix—Water-quality analyses

Figures

1. Map showing location of the study area in the Powder River Basin, Wyoming
2. Diagram showing systems for numbering springs and wells
3. Generalized stratigraphic column of the Wasatch and Fort Union Formations in the central Powder River Basin, Wyoming
4. Map showing generalized geology, clinker in the study area, lines of geologic cross sections, and ground-water sampling locations in the eastern Powder River Basin, Wyoming, 1999
5. Diagram showing correlation of coal beds in the Powder River coal field, eastern Powder River Basin, Wyoming
6. (left page, right page) Geologic cross sections, eastern Powder River Basin, Wyoming
7. Chart showing relation of Cenozoic stratigraphic units to hydrogeologic units, eastern Powder River Basin, Wyoming
8. Map showing generalized geology, potentiometric contours for Wyodak-Anderson coalbed aquifer, and ground-water sampling locations in the study area, eastern Powder River Basin, Wyoming, 1999
9. Map showing coal-lease areas, coalbed methane permitted or production wells, and ground-water sampling sites in the study area, eastern Powder River Basin, Wyoming, 1999

10-12. Graphs showing:

10. Physical characteristics of ground water, eastern Powder River Basin, Wyoming, 1999
11. General mineral characteristics of ground water, eastern Powder River Basin, Wyoming, 1999
12. (left page, right page) Concentrations of major ions in ground water, eastern Powder River Basin, Wyoming, 1999

13. Trilinear diagram showing water types for ground-water samples collected from springs, Wasatch aquifer, and coalbed aquifers, eastern Powder River Basin, 1999
14. Stiff diagrams for ground-water samples collected from coalbed methane production wells, monitoring wells, and springs, and generalized geology in the study area, eastern Powder River Basin, Wyoming, 1999

15-19. Graphs showing:

15. Calcium and sulfate concentrations in relation to well depth, Wasatch aquifer, eastern Powder River Basin, Wyoming, 1999
16. Potassium concentrations in relation to well depth, coalbed aquifers, eastern Powder River Basin, Wyoming, 1999
17. (left page, right page) Calcium, magnesium, sodium, bicarbonate, and sulfate concentrations in relation to the clustered wells W5, W4, W3, and C12 in the eastern Powder River Basin, Wyoming, 1999
18. (left page, right page) Calcium, magnesium, sodium, bicarbonate, and sulfate concentrations in relation to the clustered wells W8 and C17 in the eastern Powder River Basin, Wyoming, 1999
19. (left page, right page) Calcium, magnesium, sodium, bicarbonate, and sulfate concentrations in relation to the clustered wells W7 and C16 in the eastern Powder River Basin, Wyoming, 1999

20. Diagram of conceptual model of major-ion composition in relation to hydrogeologic units, eastern Powder River Basin, Wyoming

21-23. Graphs showing:

21. Relation between d¹⁸O (oxygen-18/oxygen-16 isotopic ratio) and d²H (deuterium/hydrogen isotopic ratio) for ground-water samples collected from springs discharging from clinker, the Wasatch aquifer, and coalbed aquifers, eastern Powder River Basin, Wyoming, 1999
22. (left page, right page) d²H (deuterium/hydrogen isotopic ratio), d¹⁸O (oxygen-18/oxygen-16 isotopic ratio), and major-ion chemistry in relation to the clustered wells W5, W4, W3, and C12 in the eastern Powder River Basin, Wyoming, 1999
23. (left page, right page) d²H (deuterium/hydrogen isotopic ratio), d¹⁸O (oxygen-18/oxygen-16 isotopic ratio), and major-ion chemistry in relation to the clustered wells W7 and C16 and clustered wells W8 and C17 in the eastern Powder River Basin, Wyoming, 1999

24-25. Maps showing:

24. d²H (deuterium/hydrogen isotopic ratio) values for coalbed aquifers in the study area, eastern Powder River Basin, Wyoming, 1999
25. d²H (deuterium/hydrogen isotopic ratio) values for springs discharging from clinker and for wells completed in the Wasatch aquifer in the study area, eastern Powder River Basin, Wyoming 1999

26. Diagram showing suitability of water for use in irrigation based on analyses of water from springs, Wasatch aquifer, and coalbed aquifers, eastern Powder River Basin, Wyoming, 1999

Tables

1. Identification numbers, well-completion information, water levels, geologic units, and assigned hydrogeologic units for wells sampled in the study area
2. Differences in water-level elevations and hydraulic potential for vertical ground-water flow in monitoring-well clusters
3. Source or cause, and significance of dissolved-mineral constituents and physical properties of water
4. Calculated relative-percent differences between normal environmental and replicate ground-water samples
5. Summary of water-quality data for ground-water samples collected from wells completed in the Wasatch aquifer
6. Summary of water-quality data for ground-water samples collected from wells completed in coalbed aquifers
7. Results of rank-sum tests between Wasatch aquifer and coalbed aquifers
8. Kendall's tau correlation coefficients and resulting probabilities (p-values) between dissolved solids or major ions and well depth, Wasatch aquifer
9. Kendall's tau correlation coefficients and resulting probabilities (p-values) between dissolved solids or major ions and well depth, coalbed aquifers
10. Tritium concentrations in ground-water samples collected from springs and wells
11. d²H (deuterium/hydrogen isotopic ratio) and d¹⁸O (oxgen-18/oxygen-16 isotopic ratio) values for ground-water samples collected from springs discharging from clinker and wells completed in the Wasatch aquifer and coalbed aquifers
12. Comparison of ground-water-quality samples collected from wells with selected U.S. Environmental Protection Agency maximum and secondary maximum contaminant levels for public drinking-water supplies
13. Comparison of ground-water-quality samples collected from wells with selected State of Wyoming standards for domestic use
14. Hardness classification of ground-water-quality samples collected from wells
15. Comparison of ground-water-quality samples collected from wells with selected State of Wyoming standards for agricultural (irrigation) and livestock use

CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATIONS

Temperature can be converted to degrees Fahrenheit (°F) or degrees Celsius (°C) as follows:

°F = 9/5 (°C) + 32
°C = 5/9 (°F - 32)

Sea level: In this report "sea level" refers to the National Geodetic Vertical Datum of 1929--a geodetic datum derived from a general adjustment of the first-order level nets of the United States and Canada, formerly called Sea Level Datum of 1929.

Abbreviated water-quality units used in this report:

Abbreviations used in this report: