Introduction 1 Purpose and scope Location and features of the study area Related studies Acknowledgments The natural hydrologic system Stratigraphy Aquifer characteristics Water levels ' Recharge and discharge Water quality 27 The simulated hydrologic system 31 Model description 31 The steady-state model The transient-state model Model simulations Base conditions Groundwater development plans Satellite well field Metropolitan well field Pumpage for park and golf course irrigation Bedrock storage of municipal water 61 Conclusions References cited 68 Supplemental information Historical pumpage estimates Future pumpage estimates 70 Modeling errors and limitations 70 10. Water-level hydrograph for the Arapahoe aquifer near the Colorado State Capitol 11. Map showing measured water-level changes in the aquifers between and 1978 12. Graph showing estimated pumpage from bedrock wells, 1958-78 13. Map showing dissolved-solids and dissolved-sulfate concentrations in the bedrock aquifers 14. Map showing size and distribution of grid blocks used in the transient-state model 15. Diagram showing mean-square-error configuration during steady-state calibration 16. Graph showing historical and projected pumpage for the bedrock aquifers 17-24. Maps showing incremental water-level declines for a satellite well field in the: 17. Dawson aquifer, using STDY pumpage estimate 18. Denver aquifer, using STDY pumpage estimate 19. Arapahoe aquifer, using STDY pumpage estimate 20. Laramie-Fox Hills aquifer, using STDY pumpage estimate 21. Dawson aquifer, using FULL pumpage estimate 22. Denver aquifer, using FULL pumpage estimate 23. Arapahoe aquifer, using FULL pumpage estimate 24. Laramie-Fox Hills aquifer, using FULL pumpage estimate 51 25. Water-level hydrographs for the Laramie-Fox Hills aquifer at Parker 26-31. Maps showing incremental water-level declines for a metropolitan well field in the: 26. Denver aquifer, using STDY pumpage estimate 27. Arapahoe aquifer, using STDY pumpage estimate 28. Laramie-Fox Hills aquifer,-using STDY pumpage estimate 29. Denver aquifer, using FULL pumpage estimate 30. Arapahoe aquifer, using FULL pumpage estimate 31. Laramie-Fox Hills aquifer, using FULL pumpage estimate 32. Map showing incremental water-level decline in the Arapahoe aquifer due to park and golf course pumpage, using HALF pumpage estimate 33-34. Maps showing incremental water-level change in the Arapahoe aquifer at site 1: 33. After 4 years of injection, using STDY pumpage estimate 62 34. After 1 year of pumping, using STDY pumpage estimate 63 35-36. Maps showing incremental water-level change in the Arapahoe aquifer at site 2: 35. After 4 years of injection, using STDY pumpage estimate 64 36. After 1 year of pumping, using STDY pumpage estimate 65 37. Graphs showing hypothetical effects of modeling conditions on simulation accuracy 72 TABLES Page TABLE 1. Porosity and specific-yield statistics for water-yielding materials 15 2. Estimated total and recoverable ground water in storage in the Denver basin 18 3. Typical bedrock water quality ...

Model-calculated drawdown in layer 5 produced by pumping mine near tract C-a at 5 cubic feet per second.. 33. Model-calculated decrease in dissolved-solids concentrations in layer 2 produced by pumping mine near tract C-a at 5 cubic feet per second. ........ 3l+. Model-calculated change in di ssol ved-sol ids concentrations in layer 5 produced by pumping mine near tract C-a at 5 cubic feet per second. ........ 35-37. Graphs showing: 35. Change in model-calculated groundwater discharge and dissolved-solids concentrations in Yellow Creek valley produced by pumping mine near tract C-a at 5 cubic feet per second .

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Introduction Purpose and scope Location and features of the study area Related studies Acknowledgments The natural hydrologic system Stratigraphy Aquifer characteristics Water levels ' Recharge and discharge Water quality The simulated hydrologic system Model description The steady-state model The transient-state model Model simulations Base conditions Ground-water development plans Satellite well field Metropolitan well field Pumpage for park and golf course irrigation Bedrock storage of municipal water Conclusions References cited Supplemental information Historical pumpage estimates Future pumpage estimates Modeling errors and limitations ILLUSTRATIONS [Plates are in pocket] PLATE 1. Map showing measured 1978 potentiometric surfaces of bedrock aquifers in the Denver basin, Colorado. 2. Map showing model-calculated 1978 potentiometric surfaces of bedrock aquifers in the Denver basin, Colorado. 3-5. Maps showing model-calculated 2050 potentiometric surfaces of bedrock aquifers in the Denver basin, Colorado: 3. Model simulation STDY-BASE. 4. Model simulation HALF-BASE. 5. Model simulation FULL-BASE.

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Introduction Purpose and scope Acknowledgments Location of the area General discussion of the groundwater model Nodal network for the groundwater model Hydrology of Indian Wells Valley Aquifer characteristics and groundwater flow Aquifer parameters Steady-state groundwater recharge and discharge Non-steady-state groundwater recharge and discharge The groundwater model Assumptions required for modeling Verification of the model Steady-state water levels Non-steady-state water levels Predictions by the model Additional data requirements Selected references ILLUSTRATIONS MATHEMATICAL GROUNDWATER MODEL OF INDIAN WELLS VALLEY, CALIFORNIA

In 1987, the U.S. Geological Survey began an investigation to obtain detailed geologic and hydrologic data pertaining to the bedrock aquifers in the Denver basin and to evaluate techniques for estimating aquifer characteristics by use of core analyses, aquifer tests, and geophysical logs. This report contains data collected during this investigation at a test site at Castle Pines, Colorado. Data consist of lithologic descriptions of about 2,400 feet of drill core and laboratory determinations of mineralogy, grain size, bulk and grain density, porosity, specific yield, and specific retention for selected core samples. Water-level data, atmospheric-pressure measurements, aquifer-compression measurements, and borehole geophysical logs also are included.

GROUND WATER ATLAS OF THE UNITED STATES CONVERSION FACTORS Hydrologic Investigations Atlas 730-C FOREWORDThe Ground Water Atlas of the United States presents a comprehensive summary of the Nation's ground-water resources, and is a basic reference for the location, geography, geology, and hydrologic characteristics of the major aquifers in the Nation. The information was collected by the U.S. Geological Survey and other agencies during the course of many years of study. Results of the U.S. Geological Survey's Regional Aquifer-System Analysis Program, a systematic study of the Nation's major aquifers, were used as a major, but not exclusive, source of information for compilation of the Atlas.The Atlas, which is designed in a graphical format that is supported by descriptive discussions, includes 13 chapters, each representing regional areas that collectively cover the 50 States and Puerto Rico. Each chapter of the Atlas presents and describes hydrogeologic and hydrologic conditions for the major aquifers in each regional area. The scale of the Atlas does not allow portrayal of minor features of the geology or hydrology of each aquifer presented, nor does it include discussion of minor aquifers. Those readers that seek detailed, local information for the aquifers will find extensive lists of references at the end of eac h chapter.An introductory chapter presents an overview of ground-water conditions Nationwide and discusses the effects of human activities on water resources, including saltwater encroachment and land subsidence.