Oil Shale, Water Resources, and Valuable

of the Piceance Basin, Colorado: 

the Challenge and Choices of Development

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MAJOR CRUDE-AND SHALE-OIL REGIONS OF THE WORLD

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1310
COVER: Estimated shale-oil resources and crude-oil reserves in selected regions of the world. 

Economic extraction of the shale-oil resources is currently or potentially feasible, but the part 

of the shale oil that is actually recoverable can only be estimated. The crude-oil reserves represent the volume of crude oil that could be economically extracted or produced at the present. Estimates of resources and reserves need to be adjusted continually to account for new 

discoveries, additional field data, changes in processing methods, and depletion during 

development.
OIL SHALE, WATER RESOURCES,

AND VALUABLE MINERALS

OF THE PICEANCE BASIN, COLORADO:

THE CHALLENGE AND CHOICES 

OF DEVELOPMENT

Compiled by O. JAMES TAYLOR

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1310

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1987
DEPARTMENT OF THE INTERIOR

DONALD P. MODEL, Secretary

U.S. GEOLOGICAL SURVEY

Dallas L. Peck, Director

Library of Congress Cataloging in Publication Data

Oil shale, water resources, and valuable minerals of the Piceance basin, Colorado.

(Geological Survey professional paper ; 1310)

Bibliography: p.

Supt. of Docs, no.rl 19.16:1310

1. Oil-shales Colorado Piceance Creek Watershed. 2. Water-supply Colorado Piceance Creek 

Watershed. 3. Mines and mineral resources Colorado Piceance Creek Watershed. 

I. Taylor, O. James. II. Series. 

TN859.U52P536 1987 553.2'82 83-600336

For sale by the

Books and Open-File Reports Section

U.S. Geological Survey

Federal Center

Box 25425 

Denver, CO 80225

0 5 ID 15 KILOMETERS
FOREWORD

The Piceance basin of northwestern Colorado contains vast resources large quantities of oil shale, valuable minerals, and water. The development of these resources 

could benefit our Nation by satisfying the future requirements of industry, agriculture, 

and municipalities.

The origin, abundance, and development of these resources are being studied by 

government, industry, and universities. Investigations indicate that the shale oil, 

minerals, and water occur together in complex relations that are only partly understood, and more intensive studies are needed if these resources are to be properly 

developed. Large-scale development of oil shale will require tremendous quantities 

of water. Unexplored ground-water reservoirs may be able to provide part of the 

required supplies. Because development may also affect the streams, ground water, 

and atmosphere, well-planned controls are needed. Proper resource development also 

will require close cooperation between industry and various levels of government.

This paper was prepared by a variety of specialists within the U.S. Geological 

Survey. The technical information is presented in a clear, graphic manner to enable 

the report to be understood by a wide spectrum of readers and to provide them with 

a broad understanding of the challenge and choices of development of the shale oil, 

minerals, and water resources of the Piceance basin.

Dallas I. Peck, Director 

U.S. Geological Survey

CONTENTS

DEFINITIONS AND SYNOPSIS Rage

GLOSSARY

A variety of technical terms describe the minerals, geology, and hydrology of the XV 

Piceance basin and the proposed resource development.

INTRODUCTION 

By O. James Taylor

The Piceance basin lies in northwestern Colorado and contains large quantities of 1 

oil shale, associated minerals, and other minerals. The occurrence of major minerals 

and the development, benefits of development, and impacts of development of oil 

shale are described in this report.

GEOLOGY, MINERALS, AND MINERAL DEVELOPMENT

GENERAL GEOLOGY OF THE PICEANCE BASIN 

By Marjorie E. MacLachlan

The Piceance basin is a structural basin, a depositional basin, and several drainage 7 

basins. The oil shale, associated minerals, and thousands of feet of sedimentary rock 

were deposited during Tertiary time, at the end of the period of deformation that 

shaped the structural basin.

ORIGIN OF THE OIL SHALE AND ASSOCIATED MINERALS 

By John R. Dyni

Oil shale, nahcolite, and dawsonite originated in ancient lakes. 17

STOREHOUSE OF ENERGY MINERALS IN THE PICEANCE BASIN 

By John R. Donnell

The Piceance basin contains natural gas, crude oil, and coal, as well as shale oil, 21 

nahcolite, and dawsonite.

VII
VIII CONTENTS

DEVELOPMENT OF THE OIL SHALE AND ASSOCIATED Page

MINERALS

By G. A. Miller

Mineral development will disrupt natural conditions in the basin because of the 29

required mining, retorting, water development, mineral transportation, and

reclamation.

RELATIONS AMONG THE GEOLOGIC, HYDROLOGIC, AND 

GEOCHEMICAL CHARACTERISTICS OF THE BASIN

SYSTEMATIC JOINTS WITHIN OIL SHALES AND ASSOCIATED 

ROCKS OF THE GREEN RIVER FORMATION 

By Earl R. Verbeek and Marilyn A. Grout

Joints and fractures of the Green River Formation form systematic patterns. The joints 45 

and fractures affect the occurrence of ground water and mine stability.

UNCONSOLIDATED DEPOSITS OF THE PICEANCE BASIN 

By Frank A. Welder

The unconsolidated deposits that overlie the bedrock contain water and are part of 57 

the hydrologic systems in the stream valleys.

HYDROLOGIC SYSTEM OF THE PICEANCE BASIN 

By O. James Taylor

Surface water and ground water flow in complex systems. An understanding of the 63 

flow systems is obtained by preparing models that simulate the systems under various 

conditions. Water supplies in the Piceance basin belong to the public, but are regulated 

by the State of Colorado.

SUSPENDED SEDIMENT IN PICEANCE CREEK 

By Vernon W. Norman

Studies of suspended sediment in Piceance Creek indicate a high erosion potential 77 

in the drainage basin under natural conditions. Increased erosion and transport of 

sediment may result from mining and waste-disposal activities.

WATER QUALITY IN THE PICEANCE BASIN 

By Robert L. Tobin

The quality of surface water and ground water is highly variable and probably will 81 

change as a result of mine drainage and mine abandonment.
CONTENTS IX

APPRAISAL OF WATER QUALITY IN PICEANCE CREEK USING Page

BENTHIC INVERTEBRATES 

By Kenneth J. Covay

A study of aquatic insects can be used to assess natural and man-induced changes

in the water quality in streams. 87

PLANNING FOR MINERAL DEVELOPMENT: 

ALTERNATE WATER SUPPLIES AND EFFECTS OF RETORTS

PALEOZOIC AND MESOZOIC FORMATIONS AND THEIR 

POTENTIAL AS GROUND-WATER RESERVOIRS 

By Marjorie E. MacLachlan and Frank E. Welder

Paleozoic and Mesozoic formations indicate a varied geologic history. These forma- 95

tions may include ground-water reservoirs that could supply water for oil-shale

development.

CHEMICAL EFFECTS AND CONTROL OF LEACHATES FROM 

OIL-SHALE SPOIL PILES 

By Kenneth G. Stollenwerk

Spoil piles of retorted shale need to be designed, located, and maintained carefully 107 

to avoid contamination of aquifers and streams.

CHEMICAL EFFECTS AND CONTROL OF WASTES FROM 

IN SITU RETORTS 

By Jerry A. Leenheer

Underground retorts may produce a variety of wastes within the ground-water 111 

reservoirs.

EFFECTS OF EMISSIONS FROM OIL-SHALE RETORTS TO 

THE ATMOSPHERE 

By John T. Turk

Industrial emissions to the atmosphere may affect precipitation and lakes. 117

LEVELS OF MINERAL DEVELOPMENT

BENEFITS, REQUIREMENTS, AND EFFECTS OF DIFFERENT LEVELS 

OF OIL-SHALE DEVELOPMENT 

By O. James Taylor

Benefits, requirements, and effects of mineral development depend on the level, dura- 125 

tion, and type of development.
CONTENTS

ADDITIONAL INFORMATION

RECOMMENDED READING page

The minerals, geology, hydrology, and resource development are described in greater 139 

detail in other publications.

EPILOGUE

EPILOGUE 143 

By O. James Taylor

ILLUSTRATIONS

1. Location and extent of the Piceance basin ......................................................... 2

2. Structural basins and uplifts ..................................................................... 7

3. Major drainage basins .......................................................................... 8

4. General geologic map of northwestern Colorado ................................................... 9

5. Principal formations of Tertiary age exposed near Anvil Points, in the southeast part of the Piceance basin 11

6. Diagrammatic east-west cross section, northwestern Colorado ....................................... 13

7. Landsat image of Piceance basin and surrounding areas ............................................ 14

8. Maximum extent of ancient Lakes Uinta and Gosiute during Eocene time ............................. 17

9. Polished slab of siltstone (light tan) and medium- to high-grade oil shale (brown to dark brown) from the

Mahogany zone ............................................................................. 17

10. Drill core of interbedded coarse crystalline white nahcolite with dark-colored oil-shale layers ........... 18

11. Nahcolite and halite deposited in the deep parts of Lake Uinta during dry climatic periods ............. 18

12. Deposition of nahcolite, dawsonite, halite, and oil shale in Lake Uinta ............................... 19

13. Drill core showing coarse crystalline scattered aggregates of nahcolite in high-grade oil shale ............ 20

14. Drill core of alternating thin beds of nahcolite and halite in which drilling fluid has dissolved part of the halite

beds ........................................................................................ 20

15. Location of large concentrations of energy minerals in the stratigraphic column ....................... 22

16. Rich and lean oil-shale zones in part of the Green River Formation in the Piceance basin ............... 23

17. Three samples of oil shale of different grade ...................................................... 24

18. Sample of nahcolite from Piceance basin .......................................................... 25

19. Total shale-oil resources and overburden thickness above the Mahogany zone ......................... 26

20. Mineral ownership in the Piceance basin .......................................................... 27

21. Modern and historic sites related to oil-shale development .......................................... 30

22. Spoil pile of retorted shale from the experimental retort of the U.S. Bureau of Mines, 1925-29 .......... 31

23. Oil-shale plants at Federal lease tracts C-a and C-b ................................................ 32

24. Surface mining using a migrating open pit ........................................................ 34

25. Underground mining using room-and-pillar method ................................................ 35

26. Samples of crushed but unretorted oil shale and retorted oil shale from field tests, Rulison site, 1928 .... 36

27. Water requirements for shale-oil production ....................................................... 38

28. Retorted shale production ....................................................................... 39

29. Revegetation of retorted shale at test plots ........................................................ 40

30. A well-developed set of joints, with an average spacing of about one foot, within moderate-grade oil shales

of the Piceance basin ......................................................................... 47

31. A set of F2 joints in moderately rich oil shales near the mouth of Piceance Creek ...................... 48

32. Schematic block diagram of joint sets in the Green River Formation ................................. 51
CONTENTS XI

33. Relation between spacing of F2 joints and bed thickness for fine-grained sandstones and siltstones of the Green

River Formation near Rio Blanco .............................................................. 53

34. Closely spaced joints in an upper lean zone, about six feet thick, and widely spaced in joints in a lower rich

zone of the Mahogany ledge near the junction of Piceance Creek and the White River ............... 54

35. Locations of cross sections where the valley-fill alluvium was explored by drilling ..................... 58

36. Alluvial deposits along stream valleys ............................................................ 59

37. Lake and alluvial deposits along stream valleys .................................................... 60

38. Lake formation in Piceance basin ................................................................ 61

39. Aerial view showing the displacement of Piceance Creek toward a county road by an alluvial fan at the mouth

of a tributary valley .......................................................................... 62

40. The Upper Colorado River Basin ................................................................ 64

41. Normal annual precipitation in Piceance basin, 1931-60 ............................................ 65

42. Major drainage basins of Piceance basin .......................................................... 66

43. Mean monthly discharge near the mouths of major streams ......................................... 67

44. Hydrologic flow components simulated in watershed model ......................................... 68

45. Map of drainage basin subdivided into hydrologic response units for watershed modeling .............. 69

46. Diagrammatic east-west sections of hydrologic system .............................................. 70

47. Diagrammatic north-south section of hydrologic system ............................................ 71

48. Natural flow system along Piceance and Yellow Creek valleys ....................................... 73

49. Gains and losses along selected reaches of Piceance Creek, March 26, 1981 ........................... 74

50. Framework for ground-water model of Piceance basin .............................................. 75

51. Hillside erosion near Rio Blanco after rainstorm, July 18, 1976 ...................................... 77

52. Turbid water in Piceance Creek near Rio Blanco, July 17, 1977 ...................................... 78

53. Coarse sediment deposited on highway near Piceance Creek during intense rainstorm, July 19, 1977 ..... 78

54. Typical yearly distribution of sediment load in streams in the Piceance basin ......................... 79

55. Deeply cut channel in streambed of Corral Gulch, resulting from well discharge, April 3, 1978 .......... 80

56. Dominant chemical constituents in the two major bedrock aquifers .................................. 82

57. Alkali flats, marked by white salts on the land surface in Piceance Creek valley, with White River valley in

the background .............................................................................. 83

58. Flow and water-quality variations in Piceance Creek, March 26, 1981 ................................ 84

59. Benthic invertebrates as part of the animal kingdom ............................................... 88

60. Changes in dissolved-oxygen concentration in streams and related changes in groups of benthic invertebrates 88

61. Benthic invertebrates that live in the bottom of streams ............................................ 89

62. Samples of benthic invertebrates collected at six locations in the Piceance Creek basin ................. 90

63. Proportions of benthic organisms along Piceance Creek ............................................. 91

64. Distribution of Paleozoic rocks under the Piceance structural basin .................................. 98

65. Water draining from the Leadville Limestone, flowing into Rifle Creek and over Rifle Falls ............. 100

66. The Leadville Limestone of Mississippian age, which may be an aquifer .............................. 101

67. Weber Sandstone of Permian age ................................................................ 102

68. Distribution of Mesozoic rocks under the Piceance structural basin .................................. 103

69. The Morrison Formation and Entrada Sandstone of Jurassic age, which may be aquifers ................ 103

70. The Dakota Sandstone, Mancos Shale, and Mesaverde Group of Cretaceous age, which may be aquifers . 104

71. Diagrammatic east-west cross section, northwestern Colorado, showing distribution of rocks for systems of

Paleozoic and Mesozoic Eras .................................................................. 105

72. Concentrations of dissolved solids, molybdenum, fluoride, and boron in leachate from three different types

of oil shale .................................................................................. 108

73. Possible movement of toxic substances leaching from oil-shale spoil piles ............................. 109

74. Mine drainage, water reinjection, and wastewater disposal during in situ retort construction ............ 112

75. Active modified in situ retort .................................................................... 113

76. In situ retort after abandonment ................................................................. 114

77. Comparison of projected emissions from oil-shale retorting to measured emissions from coal-fired powerplants

in northwest Colorado ........................................................................ 117

78. Predominant wind directions in northwestern Colorado ............................................. 118

79. Titration curves that indicate the effects of adding acid to pure water and to water samples from lower Marvine

Lake and upper Island Lake ................................................................... 119
XII CONTENTS

	Page

80. Upper Island Lake (very susceptible to acidification), located in the eastern part of the Flat Tops Wilderness

Area ....................................................................................... 120

81. Sensitivity of lakes to acidification as a function of altitude ......................................... 121

82. Simulation models to quantify the range in lake acidity as a function of emissions ..................... 121

83. Effects of different levels of oil development from shale on National oil supplies ....................... 126

84. Estimated maximum available water supplies for oil-shale development in Piceance basin ............... 128

85. Natural hydrologic system before oil-shale development ............................................ 130

86. Effects of small oil-shale development on hydrologic system ......................................... 130

87. Effects of moderate oil-shale development on hydrologic system ..................................... 131

88. Effects of intense oil-shale development on hydrologic system ....................................... 131

89. Effects of presumed levels of oil development from shale on regional water supplies ................... 132

90. Estimated effects of presumed levels and types of oil development from shale on water resources ........ 134

TABLES

1. Geologic time scale ............................................................................. 10

2. Stratigraphic column of Tertiary rocks between the Colorado and White Rivers ....................... 12

3. Characteristics of joint sets in the Green River Formation ........................................... 52

4. Correlation chart showing Paleozoic and Mesozoic Formations ...................................... 96

5. Potential surface-water supplies for oil-shale development in Piceance basin ........................... 128
DEFINITIONS AND SYNOPSIS

GLOSSARY

Aboveground retort. A large container in which crushed 

oil shale is heated in order to decompose the kerogen into oil and light hydrocarbon gases.

Acidity. The ability of a solution to neutralize strong 

bases.

Alkalinity. The ability of a solution to neutralize strong 

acids.

Alluvial deposit. Unconsolidated sedimentary material 

such as clay, sand, and gravel that is eroded from 

bedrock, transported, and laid down by flowing water. 

Also known as alluvium.

Appropriation. The diversion and use of a specified quantity of water for a specified beneficial use.

Aquatic environment. The sum of all the external physical, 

chemical, and biological conditions and influences that 

affect the life and development of an organism in a body 

of water. The environment surrounding an aquatic 

organism is rarely constant. The quality of an individual's 

life in an aquatic world is directly dependent on the quality of its environment.

Aquifer. A geologic formation, group of formations, or 

part of a formation that transmits water readily and can 

supply wells or springs. Also may be regarded as an 

underground reservoir.

Atmospheric-transport and deposition model. A mathematical description of the characteristics of the regional 

atmosphere, climate, and land forms that control the 

migration of airborne particles and gases from a source 

to a site of deposition or dispersion.

Benthic invertebrate. An animal without a backbone that 

lives in or on the bottom of an aquatic environment. Included are organisms such as insects, worms, snails, 

clams, and leeches.

Biochemical degradation. The alteration or breakdown of 

a compound directly or indirectly by microorganisms such 

as bacteria or algae.

Calcining. Conversion of minerals into a calcium and 

magnesium oxide by burning and roasting.

Clastic rock. A rock that originates as broken fragments 

of preexisting rocks that are mechanically transported and 

reconsolidated. Examples include sandstone and shale.

Continental. Formed on land masses or within freshwater 

lakes.

Crude oil. Naturally occurring petroleum, as it comes from 

an oil well.

Dawsonite. NaAl(OH)2CO3 : A rare carbonate mineral 

containing sodium and aluminum that was first discovered in a dike near McGill University, Montreal, Canada. 

Dawsonite is a possible source of aluminum oxide and 

other chemicals used in industry. In recent years the 

mineral has been found in small amounts in sedimentary 

rocks in Australia, Russia, Tanzania, and Alaska. The 

world's largest occurrence is in the Colorado oil-shale 

deposits where it locally comprises about 10 percent by 

weight of the oil shale.

Depositional basin. A basin that originates because of, or 

includes, the accumulation of sediments in a low region 

of the crust of the Earth.

Diffusion. A process of natural scattering in which constituents migrate because of differences in concentration 

or temperature.

Dip. The inclination of a geologic bed, joint, fracture, or 

any planar geologic feature; measured as an angle below 

the horizontal.

Dispersion. A process of natural scattering in which constituents or contaminants migrate because of the characteristics of the flow system.

Dissolved oxygen. Oxygen that is dissolved in water. The 

oxygen comes from the atmosphere or is produced 

by aquatic plants during photosynthesis. Respiration 

by aquatic plants, animals, and bacteria consumes 

dissolved oxygen. A low concentration of dissolved oxygen in streams or lakes may indicate degraded water 

quality.

Drainage basin. A land area that collects precipitation 

water and drains it to a stream system, lake, or reservoir.

Evapotranspiration. Loss of water by evaporation from 

wet surfaces and by transpiration through plants.

Fan deposit. A cone-shaped sedimentary deposit that 

results when streams deposit sediment as they flow from 

highlands onto lowlands. Also called an alluvial fan.

Fault. A natural break in rock strata that may or may not 

result in displacement.

Filtration. The separation of suspended solids from water 

by passage through a natural or artificial porous barrier.

Flood plain. The strip of relatively flat land along a stream 

channel that is underlain by sediment deposited by the 

stream. The flood plain is covered by water during floods.

Food chain. A series of organisms in which the larger feed 

on the smaller.

XV
XVI GLOSSARY

Fracture. A break in a rock due to mechanical failure under 

stress. A general term that includes faults, joints, and 

cracks.

Gain-and-loss study. A series of stream-discharge measurements that are used to account for all changes in 

streamflow and to calculate the exchange of water between the stream and connected aquifer.

Geophysical log. A record of various characteristics of 

rock formations that is obtained by lowering a probe 

down a well or test hole, making measurements, and 

recording them using surface instruments. The measured 

characteristics include the physical, electrical, acoustical, 

or chemical properties of the formations. The interpretation of these characteristics is helpful in exploring 

for minerals and in determining rock properties.

Ground-water model. The mathematical description of a 

ground-water system used to simulate and study the 

behavior of the system, under existing, hypothetical, or 

proposed conditions.

Ground-water reservoir. An aquifer system that can be 

utilized to store and withdraw water. Access to a groundwater reservoir is normally through wells.

Halite. Nad: the mineral name for common table salt; occurs comingled with nahcolite in beds as thick as 70 feet 

in the Colorado oil-shale deposits.

Hydrocarbon trap. A stratigraphic or structural barrier to 

the upward migration of oil and gas that permits accumulation in a reservoir.

Igneous intrusive rock. A rock that originates in the molten 

or partially molten state, invades other rocks, and then 

solidifies.

In situ retort. An oil-shale retort that is constructed using 

a cavity mined within the ore, underground, in order to 

reduce mining costs.

Infiltration. The general process by which water flows into 

porous material. For example, precipitation water passing through the land surface and into the zone below, or 

water passing into a pile of waste material.

Ion. An electrically charged atom or group of atoms that 

results from the loss or gain of electrons. Most dissolved 

minerals in water occur as ions.

Ion-exchange reactions. Chemical reactions in which ions 

in solution are exchanged with chemical elements in other 

materials. For example, calcium ions in solution commonly replace sodium in clay, releasing the sodium into 

solution.

Joint. A fracture without significant displacement in a 

rock. Parallel joints are called joint sets.

Kerogen. A solid, insoluble organic material found in 

sedimentary rocks, that can be converted to petroleum 

products by destructive distillation. Diesel fuel can be 

made easily from these petroleum products; gasoline can 

be made also, but requires more upgrading.

Landsat image. An image of the Earth's surface obtained 

by sensors on a satellite. The data obtained by the sensors are stored on magnetic tape, either on the satellite 

or at a ground station. Eventually the data are processed 

and often used to prepare an image on film for inspection and analysis. The area on the ground that is shown 

in an image is a scene.

Leachate. Soluble chemical constituents removed by percolating water from a mass of material, such as a spoil 

pile of retorted shale.

Lean oil shale. For this report, oil shale that contains 15 

gallons of oil or less per ton of rock.

Leasing. A method by which one who desires to explore 

or develop minerals owned by another can contract with 

and pay the owner for these privileges. The owner is called 

the lessor; the one who leases for exploration or development is called the lessee.

Lineament. A linear feature on the surface of the Earth that 

may be an expression of fractures and faults in the rocks 

below.

Locatable mineral. A mineral deposit that can be possessed by one who marks the boundaries of his mining claim 

on the ground and publicly proclaims his claim in the proper manner.

Marine. Formed in an ocean environment; for example, 

limestone.

Marl. A poorly consolidated rock that consists of a mixture of clay and calcium carbonate and is formed in the 

bottoms of lakes, ponds, and marshes.

Marlstone. A consolidated rock that consists of a mixture 

of shale and calcium carbonate.

Mine roof. The ceiling or back in an underground mine.

Mining claim. A portion of the public mineral lands which 

a miner, for mining purposes, takes and holds in accordance with mining laws.

Model. The mathematical description of a process 

or system that is used to simulate, study, and predict 

the behavior of the system under a variety of conditions.

Model calibration. In hydrology, a process in which the 

simulated results from a model are compared with 

measurements onsite. The model is adjusted until the 

model results and field measurements are similar or equal. 

A calibrated model is likely to be more accurate in 

forecasting than an uncalibrated model.

Modified in situ retort. A special type of in situ retort in 

which 20 to 40 percent of the oil shale is mined. The remaining ore is blasted into fragments. Air and gas are injected into the retort and the fragmented shale is ignited 

at the top of the retort using an external fuel source. As 

burning proceeds downward, the heat retorts the underlying oil-shale fragments, and shale oil and gases flow 

downward to a collection site.
GLOSSARY XVII

Nahcolite. NaHCO3; a naturally occurring sodium bicarbonate mineral having the same chemical composition as 

household baking soda. Nahcolite is a potential source 

of several chemicals used in industry including the 

removal of sulfur from exhaust gases. The name of the 

mineral is derived from the chemical formula, Na-HCO-lite.

Natural discharge. Loss of water from a ground-water 

reservoir, as to a spring or stream.

Natural recharge. Addition of water to a ground-water 

reservoir, as by infiltration from precipitation, a lake, or 

a stream.

Node. In ground-water modeling, an imaginary volume 

of a ground-water flow system within which the 

hydrologic characteristics are assumed to be uniform. By 

coupling the hydrologic characteristics of the array of 

nodes of a flow system with the proper flow equations, 

a ground-water model is constructed.

Normal annual precipitation. The average annual 

precipitation recorded from 1931 to 1960.

Oil shale. A sedimentary rock that contains kerogen and 

yields hydrocarbon material when heated.

Orogeny. The process by which structures within mountain areas are formed, including uplift, thrusting, faulting, and folding.

Overburden. The consolidated or unconsolidated rock 

material that overlies a mineral deposit.

pH. A chemical symbol used to specify the hydrogen ion 

concentration in a solution. It is defined as the negative 

base 10 logarithm of the hydrogen ion concentration in 

moles per liter. A pH of 7.0 indicates a neutral solution, 

below 7.0 is acidic, and above 7.0 is alkaline.

Permeability. A property of consolidated or unconsolidated material that describes the ease with which a 

fluid may move through openings in the material under 

standard conditions. Material of high permeability may 

transmit large quantities of a fluid in a short time; material 

of low permeability may transmit large quantities of a 

fluid in a long time and (or) over a large area.

Porosity. The volume of the void space of a rock, expressed as a fraction or percentage of the volume of the whole 

rock.

Primary permeability. Rock permeability that is due to interconnected openings that were formed during deposition, such as the pores in a sandstone aquifer.

Radiometric dating. The calculation of the age of a rock, 

mineral, or water sample by chemical analysis to determine the extent of decomposition of included radioactive 

elements.

Remote sensing. A technique for detecting the nature or 

condition of the Earth's surface without touching it.

Reserve. The part of an identified resource that can be extracted and produced economically.

Resource. A concentration of naturally occurring solid, liquid, or gaseous material in or on the Earth's crust in such 

form and amount that economic extraction of a commodity from the concentration is currently or potentially 

feasible.

Retort. A vessel used to heat crushed oil shale and extract 

the organic material. This material is converted to useful 

petroleum products.

Rich oil shale. For this report, oil shale that contains 15 

gallons of oil or more per ton of rock.

Room-and-pillar mine. An underground mine in which 

large rooms are excavated by access through a shaft or 

adit. The mine roof is supported by unmined rock called 

pillars. These pillars may be removed later during withdrawal from the mine.

Rubblize. To break rock into rough fragments using 

explosives, in preparation for in situ retorting of oil 

shale.

Scrubbing equipment. Apparatus used to cleanse gases and 

vapors of impurities before they are released from a processing plant.

Secondary permeability. Rock permeability due to interconnected openings formed after deposition, such as fractures or solution channels.

Sedimentary rock. A rock formed by the consolidation of 

accumulated loose sediments. The sediment originates as 

mechanically broken fragments during erosion, chemical 

precipitates from solution, or organic remains or secretions of plants and animals.

Shale oil. Oil that is extracted from oil shale and normally 

requires reaction with hydrogen for conventional uses 

associated with crude oil.

Solute-transport model. The mathematical description of 

a hydrologic system, including dissolved constituents in 

the ground and surface water. Used to simulate and study 

the relations between the flow system and the dissolved 

constituents under various conditions.

Spoil pile. The dump where mine-waste materials are 

disposed of or piled.

Strike. The directional trend of a horizontal line in the 

plane of an inclined geologic bed, joint, fault, or structural plane. Used in conjunction with the term, dip, to 

describe a spatial orientation.

Structural basin. A downwarped or faulted zone in the 

Earth's crust resulting from large-scale movement and in 

which sediments have accumulated.

Sublimation. The change in state of a solid to a gas or vice 

versa, without becoming a liquid.

Subsidence. The settling of the Earth's surface because of 

solution action, compaction, mining, withdrawal of 

water, crustal warping, or other cause.

Surface mining. Mining in surface excavations, such as an 

open pit or strip mine.
XVIII GLOSSARY

Surface runoff. That part of the precipitation which travels 

over the soil surface to the nearest stream channel.

Tectonic. A geologic term referring to the structural and 

deformational characteristics of a large region.

Titration. A chemical method for determining the amount 

of a constituent in a solution by adding a reagent of 

known concentration to the solution and observing the 

added volume required to convert the constituent to some 

other form.

Trap. A barrier that impedes the upward migration of oil 

and (or) gas and allows either to accumulate. A stratigraphic trap may result where a rock unit of low permeability forms a barrier; a structural trap may result from 

a barrier of low permeability that is created by folding, 

faulting, or other deformation.

Turbidity current. A sediment-laden water current that 

flows by gravity down the slope and along the bottom 

of a lake or sea. Such currents can transport large volumes 

of sediment from the shore to the deepest parts of a lake 

in a short time, measured in hours or a few days. Possibly

as much as one-half of the Colorado oil-shale deposits in 

the deeper part of the Piceance basin were deposited by 

such flows.

Unconformity. A large gap in the geologic record that is 

indicated by missing rock units in the stratigraphic 

succession. The missing units either never were 

deposited or were deposited and subsequently removed 

by erosion.

Undergound mining. Mining in underground excavations, 

such as room-and-pillar mining.

Valley-fill alluvial aquifer. A saturated alluvial deposit of 

sand and gravel that underlies and normally is 

hydraulically connected to an overlying stream.

Water right. An order issued by a specific State court, 

validating an appropriation of water, and establishing a 

priority for that water use.

Watershed model. A mathematical description of a watershed, used to simulate and study the behavior of the 

watershed, under existing, hypothetical, or proposed 

conditions.


INTRODUCTION

By O. JAMES TAYLOR

THIS REPORT DESCRIBES THE OIL SHALE, 

ASSOCIATED MINERALS, WATER RESOURCES, 

AND OTHER MINERALS OF THE PICEANCE 

BASIN AND THE POSSIBLE IMPACTS OF 

OIL-SHALE DEVELOPMENT

The Piceance (pee'ahnce) basin, Colorado, contains enormous resources of shale oil, as illustrated on the cover of 

this paper. Several regions in the world have resources of 

shale oil (shown in brown) that are much larger than the 

known reserves of crude oil (shown in tan). The Piceance 

basin, which contains 1,200 billion barrels of shale oil, is 

the largest single shale-oil resource known. It has the potential to supplement the energy and petrochemical supply of 

our Nation for centuries.

The purposes of the report are:

1. To inform planners and managers of the occurrence, 

abundance, and variety of materials that occur in the Piceance basin;

2. To describe the geology and hydrology of the basin as 

they relate to mineral occurrence and development (in 

this report development refers to mineral extraction, processing, and transportation); and

3. To assess the requirements, benefits, and impacts of different levels of mineral development.

This report provides information for planners, managers, 

legislators, and others who have some technical knowledge 

of the subjects discussed; however, the social and economic 

aspects of oil-shale development are beyond its scope and 

are not included.

This report is designed to give the reader a general understanding of the natural processes that formed the Piceance 

basin as well as its rocks, minerals, and water resources. 

By studying these processes, the reader will be able to 

understand the present configuration of the basin. Mineral 

development is discussed to provide the reader with an 

awareness of the uncertainties, requirements, benefits, and 

effects of various types of development.

The Piceance basin, as described in this report, lies between the White and the Colorado Rivers in northwestern 

Colorado. The basin extends about 55 miles in the northsouth direction and about 35 miles in the east-west direction. The total area of the basin is about 1,600 square miles.

Land-surface altitudes range from about 5,600 feet along the 

north rim of the basin to about 9,400 feet in the south. The 

topography is varied and includes flood plains, rolling hills, 

steep cliffs, and deeply incised canyons.

The first part of this report focuses on the depositional 

and structural activity that formed the basin and its 

minerals. In addition to oil shale, the basin contains billions 

of tons of the important associated minerals nahcolite and 

dawsonite, as well as natural gas, crude oil, and coal.

Development of the oil shale will require extensive mining, mine drainage, and construction of retorts. In addition, 

large water supplies are needed for various aspects of oilshale development and associated activities. Ore transportation, waste disposal, and land reclamation complete the 

development phase. The expected components of oil-shale 

development are discussed to indicate the changes in the 

basin that may result from development.

The report further describes the principal features of the 

hydrologic system in Piceance basin. This basin is drained 

by Piceance, Yellow, Parachute, and Roan Creeks. Eventually these creeks may furnish water supplies for mineral 

development. Ground water is contained in valley-fill 

alluvial aquifers and in the fractures and pores of the oilshale and overlying rocks. The oil shale and overlying rocks 

are bedrock aquifers that will need to be drained locally 

before and during oil-shale development. Water pumped 

from the mines probably also will supply water for this 

development. The streams and aquifers may be considered 

a single hydrologic system because they are hydraulically 

connected.

The general water quality in the basin also is examined. 

Studies of suspended sediment in Piceance Creek indicate 

a high erosion potential. The quality of water in aquifers 

is highly variable and needs to be considered in relation to 

mine drainage. Studies of aquatic insects in the creeks provide a method to assess the effects of suspended and dissolved constituents in stream water under natural and 

development conditions.

The geologic framework of the basin is considered. The 

maximum thickness of sedimentary rock that underlies the 

oil shale and associated minerals is about 25,000 feet. Several 

qf the underlying formations may be aquifers that could furnish water for oil-shale development. However, these formations have not been tested for their water-supply 

potential.

1
OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

108°30' 1Q8°00

15 MILES

I \ 

10 15 KILOMETERS

Location and extent of the Piceance basin (fig. 1).
INTRODUCTION

Several effects of oil-shale development may require 

careful monitoring and management. The large volumes of 

retorted shale resulting from oil-shale development may be 

leached of toxic materials or eroded. The in situ retorts may 

release a variety of wastes within the bedrock aquifers. Emissions from retorts to the atmosphere may degrade precipitation and lake water.

In the final chapter, three distinct levels of oil-shale 

development are compared. The relative benefits, water requirements, sources of water supply, and effects of development are estimated.

References are omitted from the text, and are listed at the 

end of each section.

REFERENCES

Donnell, J. R., 1976, Global oil-shale resources and costs, in Meyer, R. F., 

ed., The future supply of nature-made petroleum and gas, technical 

reports: New York, Pergamon Press, p. 843-856.

U.S. Department of Energy, 1978, International petroleum annual 1978: 

Energy Data Report DOE/EIA 0042(78), 35 p.

The discussions of the Piceance basin begin with descriptions of the general geology, Tertiary geologic history, the 

structural basin, and the geologic processes that have shaped 

the basin into its present form. An awareness of the geologic 

framework of the basin is fundamental to an understanding of its minerals and water resources.

GEOLOGY, MINERALS, AND MINERAL DEVELOPMENT

GENERAL GEOLOGY OF THE PICEANCE BASIN

By MARJORIE E. MACLACHLAN

THE PICEANCE BASIN INCLUDES A 

STRUCTURAL AND DEPOSITIONAL BASIN 

AND SEVERAL DRAINAGE BASINS

The Piceance basin is an area in northwestern Colorado 

named for Piceance Creek, a major tributary of the White 

River. (See map, fig. 3.) The basin is a structural, depositional, and drainage feature, and its boundaries differ, 

depending on which aspect is under consideration.

The structural basin is a geologically downwarped region 

surrounded by uplifted regions, as shown below, including 

the Axial Basin arch, the Grand Hogback, the White River 

uplift, the Gunnison uplift, the Uncompahgre uplift, the 

Douglas Creek arch, and the Yampa plateau. Basins and 

uplifts are common in the Rocky Mountain region.

PICEANCE

STRUCTURAL

BASIN

100 MILES

100 KILOMETERS

Structural basins and uplifts (fig. 2).

The downwarped region is a depositional basin, filled with 

eroded sediments that have been consolidated to form 

sedimentary rock. Some investigators use the term Piceance 

Creek basin to describe the part of the structural and depositional basin that lies between the Colorado River on the 

south, the White River on the north, the Douglas Creek arch 

on the west, and the Grand Hogback on the east.

Stream systems drain water from precipitation into stream 

channels in the downwarped region between the Colorado 

and the White Rivers. Four major drainage basins have 

developed: Piceance and Yellow Creeks drain to the north, 

and Roan and Parachute Creeks drain to the south. Drainage 

basins are named after the principal creek within them, as 

shown below.

In this report, for convenience and simplicity, the Piceance 

basin refers to the part of the structural, depositional, and 

four major drainage basins that lie between the Colorado 

and the White Rivers. This is the region of great mineral 

concentration in which preliminary mineral development has 

begun, and it is the principal region that will be affected by 

future development.

STUDIES OF EXPOSED FORMATIONS,

WELL DRILLERS' RECORDS, AND

ROCK SAMPLES ARE USED TO DETERMINE

THE ORIGIN AND AGE OF ROCKS

AND TO SEARCH FOR INCLUDED MINERALS

Geologists collect information on bedrock in the Piceance basin by examining rocks where they are exposed, 

by studying the descriptions of subsurface rocks recorded 

by well drillers, and by examining and analyzing rock 

samples. This information allows them to identify the 

geologic processes that formed the rock and to estimate the 

geologic age during which the rock was deposited. The same 

information is used to group the rocks into formations that 

were deposited under similar conditions. By reconstructing the geologic history of the region, favorable sites can 

be selected to explore for minerals and ground-water 

reservoirs.

Rocks discussed in this report were deposited in the Piceance basin as much as hundreds of millions of years ago.
OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

10B°30' 10B°00

PARACHLj TTtREEK 

DRAINAGE BASIN

15 MILES

10 1b KILOMETERS

Major drainage basins (fig. 3).
GENERAL GEOLOGY 9

For purposes of discussion, the rocks have been subdivided 

into three age groups shown on the geologic map:

1. Precambrian,

2. Paleozoic and Mesozoic, and

3. Tertiary.

The Precambrian rocks are the oldest age group and are 

discussed only briefly. The Paleozoic and Mesozoic rocks 

contain minerals and water and can be studied directly 

where they are exposed on the margins of the basin. The 

characteristics and distribution of Paleozoic and Mesozoic 

rocks at depth below the surface in the basin have been interpreted from studies of the exposed rocks and well drillers' 

records. The rocks of the Paleozoic and Mesozoic Eras are 

discussed in greater detail in the chapter "Paleozoic and 

Mesozoic formations and their potential as ground-water 

reservoirs." Tertiary rocks are the youngest age group and 

are exposed over much of the basin. Oil shale, nahcolite, 

dawsonite, and ground water occur in sedimentary rocks 

of Tertiary age. Tertiary volcanic rocks are found at scattered localities to the south and east.

The geologic time scale indicates the time during which 

the various geologic formations were deposited. All rocks 

older than 570 million years are Precambrian, by definition. 

Precambrian rocks from 950 million to 1.8 billion years old 

are found in the Piceance basin. The Paleozoic Era lasted 

330 million years, and the Mesozoic Era lasted about 177 

million years. The Tertiary Period of the Cenozoic Era 

followed, lasted 61 million years, and ended 2 million years 

ago. The Piceance structural basin formed, mostly during 

the Tertiary Period, from Late Cretaceous into Eocene time. 

The Quaternary Period of the Cenozoic Era is of relatively 

short duration, spanning the last 2 million years. The other 

periods and epochs are of very different durations, as indicated in the geologic time scale.

The Tertiary rocks are discussed first because they contain the oil shale, major mineral deposits, and important 

ground-water resources. Representative formations of Tertiary age are shown in the stratigraphic column. Paleocene 

and Eocene sedimentary rocks are exposed in a large area 

between the Colorado and the White Rivers. Isolated exposures of Paleocene and Eocene rocks also are found south 

of the Colorado River. The Oligocene is represented only 

by igneous intrusive rocks in the West Elk Mountains at the 

southeast end of the structural basin. Volcanic rocks erupted 

on Grand Mesa, due east of Grand Junction, during the 

Miocene Epoch about 9 million years ago. No Pliocene rocks 

have been identified.

Tertiary sedimentary rocks are divided into four principal 

formations. The oldest are the Fort Union and Wasatch Formations of Paleocene age, which contain natural gas. The 

Fort Union Formation is exposed in a narrow band on the 

northeast side of the basin, extending from near the town 

of Meeker northward to near the Axial Basin arch. The

lower part of the Wasatch Formation is exposed in the 

southern part of the basin, and the upper part, of Eocene 

age, underlies the entire basin. Two younger Eocene units, 

the Green River and the Uinta Formations, occupy successively smaller areas in the basin. The Green River Formation contains the oil shale, nahcolite, dawsonite, ground 

water, natural gas, and crude oil. These four formations 

comprise a section of Tertiary rock that is probably more

109° 108°

0 25

i I

50 MILES

0 25 50 KILOMETERS 

EXPLANATION

3S18

; TJJ

TERTIARY 

VOLCANIC

ROCKS

TERTIARY 

SEDIMENTARY 

ROCKS

M*

ft

i mi im "in

MESOZOIC 

ROCKS

PALEOZOIC 

ROCKS

PRECAMBRIAN 

ROCKS

General geologic map of northwestern Colorado (fig. 4).
10 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO. 

TABLE 1 . Geologic time scale

GEOLOGIC TIME SCALE

Cenozoic 

Era

Mesozoic 

Era

Paleozoic 

Era

Quaternary 

Period

Tertiary 

Period

Holocene Epoch

Pleistocene Epoch

Pliocene Epoch

Miocene Epoch

Oligocene Epoch

Eocene Epoch

Paleocene Epoch

Cretaceous Period

Jurassic Period

Triassic Period

Permian Period

Pennsylvanian Period

Mississippian Period

Devonian Period

Silurian Period

Ordovician Period

Cambrian Period

Precambrian

ESTIMATED 

AGE, IN 

MILLIONS 

OF YEARS

Present 

 0.01 

 2 

*J

 24 

 30

«J«J 

oo

1 oO 

O/^c

 240 

£- *J\J

oovy

ifr\ obU

 410 

-TOO

 500- 

*J / \J

DURATION, 

IN 

MILLIONS 

OF YEARS

3

19

14

17

8

75

67

35

50

40

30

50

25

65

70

than 11,000 feet thick. Sedimentary rocks younger than late 

Eocene have not been identified with certainty in the Piceance basin.

THE STRUCTURAL BASIN WAS FORMED 

DURING THE LARAMIDE OROGENY

Studies of the tectonic features of the region also provide 

information on the geologic history that relates to the occurrence of minerals and water. The Piceance structural 

basin was formed during the Laramide orogeny, a mountainbuilding process of thrusting, faulting, and folding. The 

orogeny lasted at least 10 million years from Late Cretaceous 

to Eocene time. The structural basin resulted from subsidence that accompanied the mountain building in adjacent 

regions. The structural basin also was a basin of deposition; 

erosion of some of the surrounding highlands furnished the 

sediments that comprise the rocks of late Cretaceous and 

Tertiary age. During and after deposition, these rocks were 

altered by continued subsidence, uplifting, folding, faulting, 

and jointing. In some formations the structural deformation 

increased rock permeability and formed aquifers.

The regions surrounding the structural basin were uplifted 

at different times. The Douglas Creek arch is recognized as 

the oldest boundary structure because the Mesaverde Group 

of Late Cretaceous age and the Wasatch Formation of Eocene 

age thin toward and over the arch. This thinning indicates 

that the arch was present when the formations were being 

deposited. The Uinta and Uncompahgre areas were uplifted 

in Late Cretaceous age somewhat later than the Douglas 

Creek arch. The Axial Basin arch rose during early and middle Eocene time and formed a barrier between two ancient 

lakes while the Green River Formation and the large 

associated mineral resources were deposited. One lake was 

south of the arch in the Piceance basin, and the other was 

north of the arch. If the Axial Basin arch had not existed 

to separate the two ancient lakes, a single lake would have 

formed and the present distribution and grade of oil shale, 

nahcolite, and dawsonite undoubtedly would be different. 

The White River uplift is the youngest boundary structure.

The tremendous effect of the Laramide orogeny on the 

geologic formations in northwestern Colorado is evident in 

the structural relief in Precambrian rocks. The top of the 

subsurface Precambrian rocks near the Axial Basin arch is 

18,000 feet below sea level; in contrast, the top of the
1>J

s

so 

5n

Principal formations of Tertiary age exposed near Anvil Points, in the southeast part of the Piceance basin (fig. 5).
12 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO. 

TABLE 2. Stratigraphic column of Tertiary rocks between the Colorado and White Rivers1

ERATHEM

(part) Cenozoic 

SYSTEM

^ 

ro

C

0)

SERIES

Pliocene

Miocene

Oligocene

Eocene

Paleocene

UNIT GENERAL LITHOLOGY 

(MAXIMUM THICKNESS IN FEET)

Basalt on Grand Mesa, 9.7±0.5 million years old (200-500)

Granodiorite and related rocks of West Elk Mountains, 

29 to 34 million years old

Uinta Format

Parachu 

§ Mer

(0 _______ 

E ^

£ Gar 

\ Gu

5 ^ Men

5 iN 

c £ -

S <->.Q 

>- we

U « 5 

?5 L^

 ^ o

Wasatch Form

(n 

n

Fc 

F

mm iiTTrrmT! i m H i ITTTT

\ nil n n 1 1 n in

Gray and yellow-brown, marlstone, siltstone, 

on2 sandstone, and tuff. Intertongues with 

Green River Formation 

(1,000+)

te Creek 

nber

^- -j- Only four major members shown. Gray

/ sandstone, green to gray siltstone, 

Jen / claystone, mudstone, shale, marlch ~7 stone, oolitic algal limestone, 

iber / and dark brown oil shale. Complexly 

1 u> intertongued sequence of stream, 

c ^ swamp, nearshore, lake, mudflat, 

o -° and evaporite origin. 

- | (3,500)

^1* i ^ <

Wasatch: Varicolored clay and clay shale, 

ation3 lenticular sandstone, and conglomerate. 

Intertongues with Green River Formation

(5,000+)

orth and Fort Union: Gray, brown sandstone, lenticuortheast) \ ar t0 crossbedded, massive; brown, gray 

)rt Union shale, claystone, siltstone, mudstone, 

ormation carbonaceous shale, coaly shale, and coal 

(1,400+)

rrTTITTnTTTTrnT'ilMMMIIIIMIIIIMlinnilllMINIMIIIIIIIIItlMllllMIIIMIIIHMIIIIMIIII

1 Sources of information: Donnell, 1962; Hail, 1974; Pipiringos and Johnson, 1976; 

Pipiringos and Rosenlund, 1977; Roehler. 1974; Tweto. 1975; Tweto, 1976; Tweto, Moench, 

and Reed, 1978.

2 Cashion and Donnell (1974) extended the name Umta Formation into the basin. The 

term Uinta replaced the use of the term Evacuation Creek Member of the Green River Formation, 

which was abandoned by them.

3 Previous workers called a sandstone and conglomerate between the Wasatch and the 

Mesaverde, the Paleocene Ohio Creek Formation. This formation often was mapped with the 

Wasatch or Fort Union Formation. Johnson and May (1 980) have reassigned the Ohio Creek 

as a member of the Upper Cretaceous Hunter Canyon Formation of the Mesaverde Group

exposed Precambrian rocks on the adjacent uplifts is several 

thousand feet above sea level. In the White River uplift, the 

top of the Precambrian rocks is 28,000 feet higher than the 

top of those in the deepest part of the Piceance structural 

basin. In the Uinta uplift the difference in altitude is 26,500

feet; in the Uncompahgre uplift the difference in altitude is 

27,000 feet. Because of the structural relief, formations that 

are exposed or at shallow depths in uplifted regions may 

lie at depths of tens of thousands of feet in the Piceance 

basin.
GENERAL GEOLOGY 13

MAJOR PHYSICAL AND STRUCTURAL

FEATURES OF THE BASIN

CAN BE STUDIED ON LANDSAT IMAGES

Satellite remote sensing, in the form of Landsat imagery, 

provides a broad summary view of numerous, detailed 

features of Earth's surface. The Landsat image is obtained 

by recording the variations in reflected solar energy and 

enhancing the contrast in these variations to form a falsecolor image. On the Landsat image of the Piceance basin, 

most of the red-orange zones represent irrigated cropland, 

the brown zones indicate native trees and bushes, and the 

blue-gray zones are land areas that have little or no 

vegetation.

The streams and tributaries are prominent on the Landsat image because the irrigated land along their flood plains 

and the relief of the land surface along streams provide a 

strong contrast. The great relief of the incised valleys of 

Roan and Parachute Creek basins is striking in comparison 

to the slight relief in the Yellow and Piceance Creek basins.

Structural features are identified by their relief, effects on 

surface drainage, and color. The Piceance Creek Dome is 

identified easily by the radial pattern of its tributaries. A 

major lineament extends from the area drained by Parachute 

Creek into the White River uplift, as indicated by the dark 

color. Parachute Creek and tributaries of Piceance Creek 

and Dry Fork form an alinement that may be a structural 

feature. Several faults also are recognized by their relief and 

their effects on surface drainage.

REFERENCES

Bass, N. W., and Northrup, S. A., 1963, Geology of Glenwood Springs 

quadrangle and vicinity, northwestern Colorado: U.S. Geological Survey 

Bulletin 1142-J, 74 p.

Bradley, W. H., 1931, Origin and microfossils of the oil shale of the Green 

River Formation of Colorado and Utah: U.S. Geological Survey Professional Paper 168, 58 p.

Bryant, Bruce, 1979, Geology of the Aspen 15-minute quadrangle, Pitkin 

and Gunnison Counties, Colorado: U.S. Geological Survey Professional 

Paper 1073, 46 p.

Cashion, W. B., compiler, 1973, Geologic and structure map of the Grand 

Junction quadrangle, Colorado and Utah: U.S. Geological Survey 

Miscellaneous Investigations Map 1-736.

Cashion, W. B., and Donnell, J. R., 1974, Revision of nomenclature of 

the upper part of the Green River Formation, Piceance Creek Basin, Colorado, and eastern Uinta Basin, Utah: U.S. Geological Survey Bulletin 

1394-G, 9 p.

Donnell, J. R., 1962, Tertiary geology and oil-shale resources of the Piceance Creek basin between the Colorado and White Rivers, northwestern 

Colorado: U.S. Geological Survey Bulletin 1082-L, p. 835-891.

Gaskill, D. L., and Godwin, L. H., 1966, Geologic map of the Marble 

quadrangle, Gunnison and Pitkin Counties, Colorado: U.S. Geological 

Survey Geologic Quadrangle Map GQ-512.

Grose, L. T., 1972, Tectonics in Geologic Atlas of the Rocky Mountain 

region: Denver, A. B. Hirschfeld Press, p. 35-44.

Hail, W. J., Jr., 1974, Geologic map of the Rough Gulch quadrangle, Rio 

Blanco and Moffat Counties, Colorado: U.S. Geological Survey Geologic 

Quadrangle Map GQ-1195.

Hansen, W. R., 1965, Geology of the Flaming Gorge area, Utah-ColoradoWyoming: U.S. Geological Survey Professional Paper 490, 196 p.

Hansen, W. R., and Carrara, P. E., 1980, Geologic map of the Tanks Peak 

quadrangle, Moffat County, Colorado: U.S. Geological Survey Geologic 

Quadrangle Map GQ-1534.

EAST

EAST RIM OF 

UINTA BASIN

I <

WEST

DOUGLAS CREEK ARCH

(The oldest boundary

structure)

CATHEDRAL 

BLUFFS

PICEANCE STRUCTURAL BASIN WHITE RIVER UPLIFT

(The youngest boundary

structure)

The structural basin was 

formed as a result of uplift 

and downwarp, begining during late Mesozoic 

time

Erosion of the surrounding 

highlands resulted in sediment that was deposited 

and consolidated in the 

basin during late Mesozoic 

and Tertiary time

A large lake formed in the 

basin during early Tertiary 

time. Rich deposits of oil 

shale and other minerals 

formed in the lake

Diagrammatic east-west cross section, northwestern Colorado (fig. 6).
14 OIL SHALE, WATERI KtbUUKCtb, VALUABLE, MllNt,KAL», PICEANCE FH. EAIN^I BASIN, COLO

"'*" " "' M-/*»~3

^e^^m^^^- ^^^^M$fi& fee .^^SSg^SF^-^''- ^ 

rte *&£??** £. ,-:< 1 (?<^Wfmr£//'-/* mK^^m^^ :tf);/%-'&X''-- t& 7>V; ^'/s/f'-S'f;^- M-W^^^ :

r>-.ri-:^'' ^ \.-<^,- .-Be-.. i-^s5ilfJ

S'TM, »^aFVT/T1>* '^Btb^' f,?f l!-K IVinW-- jfF-r-* ~

I

*?'-Pf ^.»"«^tes)^^

li -. . ' .^5?r.. 4 mv&rmm, ' '^e^m

10

20

20 MILES

30 KILOMETERS

Landsat image of Piceance basin and surrounding areas (fig. 7).
GENERAL GEOLOGY 15

Johnson, R. C., and May, Fred, 1980, A study of the Cretaceous-Tertiary 

unconformity in the Piceance Creek basin, Colorado The underlying 

Ohio Creek Formation (Upper Cretaceous) redefined as a member of the 

Hunter Canyon or Mesaverde Formation: U.S. Geological Survey Bulletin 

1482-B, 27 p.

King, P. B., and Beikman, H. M., compilers, 1974, Geologic map of the

United States: U.S. Geological Survey, scale 1:2,500,000. 

Murray, F. N., 1966, Stratigraphy and structural geology of the Grand

Hogback Monocline, Colorado: Boulder, University of Colorado, Ph. D.

thesis, 219 p. 

Pipiringos, G. N., and Johnson, R. C., 1976, Preliminary geologic map

and correlation diagram, White River City quadrangle, Colorado: U.S.

Geological Survey Miscellaneous Field Studies Map MF-736. 

Pipiringos, G. N., and Rosenlund, G. C., 1977, Geologic map of the White

Rock quadrangle, Colorado: U.S. Geological Survey Miscellaneous Field

Studies Map MF-837.

Roehler, H. W., 1974, Depositional environments of rocks in the Piceance

Creek Basin, Colorado: Rocky Mountain Association of Geologists,

Guidebook No. 25, Guidebook to the energy resources of the Piceance

Creek Basin, Colorado, p. 57-64. 

Rowley, P. D., and Hansen, W. R., 1979, Geologic map of the Plug Hat

Rock quadrangle, Moffat County, Colorado: U.S. Geological Survey

Geologic Quadrangle Map GQ-1514. 

Tweto, Ogden, compiler, 1976, Geologic map of the Craig 1°X2°

quadrangle, northwestern Colorado: U.S. Geological Survey

Miscellaneous Investigations Map 1-972. 

Tweto, Ogden, Moench, R. H., and Reed, J. C., Jr., 1978, Geologic map

of the Leadville 1°X2° quadrangle, northeastern Colorado: U.S.

Geological Survey Miscellaneous Investigations Map 1-999.

The minerals nahcolite, dawsonite, and halite occur with 

the oil shale because they formed together in ancient lakes. 

A description of the depositional conditions follows.

THE ORIGIN OF OIL SHALE AND ASSOCIATED MINERALS

By JOHN R. DYNI

OIL SHALE, NAHCOLITE, AND DAWSONITE 

WERE FORMED IN ANCIENT LAKES

About 48 million years ago, during the Eocene Epoch, 

several large lakes covered thousands of square miles in parts 

of Wyoming, Utah, and Colorado. Two of these lakes have 

been named Lake Uinta and Lake Gosiute. Lake Uinta occupied two large structural basins in northeastern Utah and 

northwestern Colorado. At its maximum size, Lake Uinta 

covered about 22,000 square miles, about the size of Lake 

Michigan, and extended about 190 miles from east to west, 

and as much as 110 miles from north to south. Lake Gosiute 

occupied a structural basin in southwestern Wyoming and 

covered about 15,500 square miles.

43°112°

100 MILES 

I I _J

0 50 100 KILOMETERS

Maximum extent of ancient Lakes Uinta and Gosiute during 

Eocene time (fig. 8).

Vast quantities of oil shale accumulated as organic-rich 

marls in the deeper parts of the lakes. These marls, which 

are hundreds of feet thick, accumulated in the eastern part 

of Lake Uinta (Piceance basin in Colorado)

Polished slab of siltstone (light tan) and medium- to high-grade 

oil shale (brown to dark brown) from the Mahogany zone (fig. 9).

Other potentially valuable minerals are abundant in 

the oil-shale deposits. Nahcolite, a sodium bicarbonate 

mineral; dawsonite, a sodium aluminum carbonate mineral; 

and halite, sodium chloride (common table salt) are 

interspersed through the lower part of the oil-shale 

deposits.

Nahcolite is a potential source of soda ash, which is used 

in the manufacture of glass and many industrial chemical products. A promising new use for nahcolite is in 

removing sulfur dioxide, an environmentally harmful 

chemical, from industrial stack gases such as those produced by coal-fired electric-generating plants. Dawsonite 

is a source of aluminum that can be coproduced with the 

shale oil. In the Piceance basin, the resources of nahcolite 

are estimated to be 32 billion tons and dawsonite resources 

are estimated to be 19 billion tons, or 6.5 billion tons of 

alumina.

17
18 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Drill core of interbedded coarse crystalline white nahcolite with 

dark-colored oil-shale layers (fig. 10).

KEROGEN PROBABLY RESULTED FROM 

THE DECOMPOSITION OF ALGAE AND 

BACTERIA IN ANCIENT LAKES

Kerogen, the organic matter in oil shale, is a fine-grained 

substance composed of carbon, hydrogen, nitrogen, and 

oxygen; its complete chemical structure is unknown. When 

heated to 900 °F, the kerogen decomposes and yields a synthetic crude oil that can be refined to obtain gasoline, fuel 

oils, and lubricants.

Kerogen gives few physical clues of its origin, but most 

likely it represents the decomposition products of microscopic algae and bacteria that once thrived in the nutrientrich waters of Lake Uinta. Because the deeper waters and 

sediments of the lake were devoid of oxygen, the environment was not habitable for lake-bottom scavengers and burrowing aquatic animals. Thus, the algae and bacterial 

detritus were not consumed by higher forms of life, but were 

buried with the sediments and eventually solidified to form 

oil shale.

STREAMS CARRIED SEDIMENT AND SALTS 

INTO LAKE UINTA

The lake sediments and various soluble salts were derived 

from sedimentary rocks exposed in the drainage basin of 

Lake Uinta, which encompassed a large area in western Colorado and parts of Utah, Arizona, and New Mexico. The 

sediments and salts were carried by streams to the lake. The 

coarser sandy materials were deposited in deltas where the 

streams emptied into Lake Uinta and in fringing shallowwater mudflats and sandy bars. The finer-sized silts and 

clays were swept to the deeper parts of the lake by bottom 

and surface currents.

THE ANCIENT LAKES RESPONDED

TO CLIMATIC AND GEOLOGIC CHANGES

During its existence, the depth and extent of Lake Uinta 

changed greatly in depth and size in response to moist and 

dry r\"matic cycles. Some researchers believe Lake Uinta was 

a shallow lake that frequently became dry, whereas others 

believe the lake was a deep and permanent body of water. 

During dry periods, the lake area decreased and soluble salts 

of sodium carbonate and chloride were concentrated in the 

deepest part of the lake, chiefly in the northern part of the 

Piceance basin. The lake water became incorporated in the 

organic marls that were accumulating in the deeper parts 

of the lake. Much nahcolite precipitated within the soft marls 

as scattered clumps of crystals, which commonly are several 

inches across. With further evaporation, the lake water 

became supersaturated with sodium bicarbonate and eventually with sodium chloride and beds of nahcolite and 

halite precipitated.

108°30' 108°00'

i i

0 5 10 15 KILOMETERS

Nahcolite and halite deposited in the deep parts of Lake Uinta 

during dry climatic periods (fig. 11).
WEST EAST

UINTA MOUNTAINS

Dissolved sodium bicarbonate 

chloride, and sulfate salts

DARK-BROWN OIL SHALE-Composed of 

carbonate minerals, feldspars, quartz, 

and minor amounts of sulfide minerals (t>). 

Scattered aggregates of nahcolite (*) are 

found in the oil-shale strata that were 

deposited in deeper parts of Lake Uinta 

in the Piceance basin

EXPLANATION

(a) BEDDED NAHCOLITE-Grades laterally 

into beds of (b) MIXED HALITE AND NAHCOLITE These chemical rocks were precipitated from lake brine in the deep 

part of the basin during arid periods

SILTSTONE, MUDSTONE, AND FINEGRAINED SANDSTONE-Deposited in a 

shallow-water marginal-lake environment

FISSILE ORGANIC SHALE-lncludes lowgrade oil shale deposited in Lake Uinta

SILTSTONE, SANDSTONE, AND MUDSTONEDeposited in flood plains and stream 

channels

Deposition of nahcolite, dawsonite, halite, and oil shale in Lake Uinta (fig. 12).
20 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Drill core showing coarse crystalline scattered aggregates of 

nahcolite in high-grade oil shale (fig. 13).

Drill core of alternating thin beds of nahcolite and halite in which 

drilling fluid has dissolved part of the halite beds (fig. 14).

Sulfate was probably abundant in the lake waters, was 

reduced by bacteria to sulfide, and precipitated as pyrite in 

the sediments. Other chemical reactions within the sediments 

led to the solution of the original clay minerals and the 

precipitation, in their place, of dawsonite and quartz. These 

minerals, along with dolomite and feldspars, comprise most 

of the fine-grained minerals in the oil shale.

During dry periods when Lake Uinta had no outlet, 

brine rich in dissolved sodium, bicarbonate, chloride, and 

sulfate accumulated in the deepest part of the lake in Piceance basin. The figure shows the lake during a freshening 

period following a dry period during which a bed of 

nahcolite and halite had precipitated. A bottom turbidity 

current swept organic-rich marly sediments down the slope 

of the basin. An older high-water shoreline terrace is in the 

background above the mudflats fringing the lake. Such terraces were destroyed by erosion. A large stream may have 

connected the two large lakes and drained water from Lake 

Gosiute in southwestern Wyoming into the northern part 

of Lake Uinta in Colorado and Utah. Numerous streams also 

flowed into the lake along its southern shores.

The duration of Lake Uinta has been estimated at 13 

million or more years, based on radiometric dating of 

minerals in volcanic ash beds that were deposited with the 

lake sediments. The unusual longevity of Lake Uinta was 

made possible by continuous downwarping of the structural 

basins occupied by the lake. When downwarping ceased, 

the basins filled rapidly with sediment, and Lake Uinta disappeared about 40 million years ago.

REFERENCES

Bradley, W. H., 1931, Origin and microfossils of the oil shale of the Green 

River Formation of Colorado and Utah: U.S. Geological Survey Professional Paper 168, 58 p.

Dyni, J. R., 1981, Geology of the nahcolite deposits and associated oil shales 

of the Green River Formation in the Piceance Creek basin, Colorado: 

Boulder, University of Colorado, unpublished Ph. D. thesis, 144 p. 

.1982, Colorado nahcolite deposits: Geology and outlook for development: American Institute of Mining Engineers Transactions, v. 270, 

p. 1853-1859.

Lundell, L. L., and Surdam, R. C., 1975, Playa-lake deposition: Green River 

Formation, Piceance Creek Basin, Colorado: Geology, v. 3, p. 493-497.

Ryder, R. T., Fouch, T. D., and Elison, J. W., 1976, Early Tertiary sedimentation in the western Uinta Basin, Utah: Geological Society of America 

Bulletin, v. 87, p. 496-512.

Piceance basin not only contains huge resources of oil shale 

and evaporite minerals, but also a variety of other minerals. 

Their occurrence is described in the following chapter.
STOREHOUSE OF ENERGY MINERALS IN THE PICEANCE BASIN

By JOHN R. DONNELL

PICEANCE BASIN CONTAINS A WEALTH 

OF MINERAL RESOURCES, INCLUDING 

NATURAL GAS, CRUDE OIL, COAL, 

SHALE OIL, NAHCOLITE, AND DAWSONITE

The uppermost 10,000 feet of sedimentary rocks in the 

Piceance basin is a repository for one of the largest energy 

reserves in the world. Natural gas is produced in considerable quantities from several zones at depths ranging 

from about 2,000 to 10,000 feet. Additional trillions of cubic 

feet of gas are trapped in sandstone of low permeability between depths of 6,000 and 10,000 feet in the Mesaverde 

Group of Cretaceous age. The gas originated in sandstone 

strata interbedded with coal and organic-rich shale. Commercial production is dependent on development of production techniques that will release the gas from the clay-filled 

pores of the sandstone.

Small quantities of crude oil that originated from carbonaceous material are obtained from shallow depths in the 

lower part of the Green River Formation. The favorable 

geologic conditions for oil production a thick sequence of 

sedimentary rocks, source rocks, reservoir rocks, structural 

traps, and stratigraphic traps all exist in the Piceance basin. 

Essentially all formations that comprise the more than 25,000 

feet of sedimentary rocks underlying the basin yield crude 

oil elsewhere in the Rocky Mountain area.

Bituminous coal of low sulfur and ash content originated 

from the compaction and hardening of plant remains; the 

coal is mined where the Mesaverde Group is exposed, 

especially south of the Colorado River. These coal beds also 

underlie, generally at a depth of less than 8,000 feet, the entire part of the Piceance basin that contains oil shale in the 

Green River Formation. The estimated in-place coal resource 

is 60 billion tons, a tremendous energy resource.

By far the greatest concentrated hydrocarbon resource in 

the world is that of the oil shales contained in the Green 

River Formation of Colorado, Utah, and Wyoming. The Piceance basin alone contains shales that attain a maximum 

thickness of 2,000 feet and have an average content of 

kerogen that will convert to more than one-third of a barrel of shale oil per ton of rock. The total in-place resource 

is about 1,200 billion barrels of shale oil. Associated with 

the oil shale are billions of tons of the evaporite minerals,

nahcolite and dawsonite, which have a considerable 

byproduct value for a future oil-shale industry.

OIL SHALE OCCURS IN RICH 

AND LEAN ZONES

Throughout an area of about 600 square miles in the 

northern part of the basin, the oil shale is contained in seven 

rich oil shale zones separated by six lean oil-shale zones. Rich 

zones are numbered with R- prefixes and lean zones are 

numbered with L- prefixes. Near the northwestern, eastern, 

and southern margins of the basin the organic content of 

the beds decreases in all the rich zones except the Mahogany 

zone and the upper part of the R-6 zone. The intervening 

lean oil-shale zones, representing major decreases in the size 

of Lake Uinta, grade laterally into sandstone or siltstone containing no kerogen. Therefore, at the edge of the basin only 

the Mahogany zone and the upper part of the R-6 zone are 

easily recognized.

In an area of about 100 square miles near the depositional 

center of the basin, thick beds of nahcolite and halite, 

deposited during minor decreases in the size of Lake Uinta, 

are interspersed with the rich oil-shale beds. Also in this area 

the lean oil-shale beds are enriched in organic matter, thus 

providing little contrast between the rich and lean zones.

At the northern end of the basin, the 500-foot section immediately overlying the Mahogany zone consists predominantly of sandstone. In the southern part of the basin this 

sandstone intertongues with and is replaced by oil shale that 

contains 10 to 15 gallons of shale oil per ton of rock.

Within the Garden Gulch Member of the Green River Formation, a zone of low electrical resistivity on geophysical 

logs is referred to as the orange zone. Although the orange 

zone in the center of the basin marks the base of oil shale 

of current economic interest, an additional 150 to 200 feet 

of lean oil shale lies immediately below the orange zone. 

Midway between the southern margin and the depositional 

center of the basin, the oil-shale sequences occur above the 

Mahogany zone and below the orange zone, in addition to 

the seven rich and six lean oil-shale zones. In this area the 

continuous sequence of oil shale is more than 2,000 feet 

thick.

21
22 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Top of Mahogany ledge

FEET

Green River 

Formation

Wasatch 

Formation

Fort Union 

Formation

Mesaverde 

Group

Mane os 

Shale

 1000

JT^ J"P> Jf^ ^n

-2000

-3000

4000

 5000

>fT ^r> "TP 't^

B sand

(Probably equivalent to the 

Emery Sandstone Member)

 6000

 7000

8000

-9000

 10,000

PICEANCE BASIN

EXPLANATION

RICH OIL-SHALE ZONE 

BEDDED HALITE

7///////////J BEDDED NAHCOLITE

MINOR OIL-PRODUCING ZONE

Location of large concentrations of energy minerals in the stratigraphic column (fig. 15).
STOREHOUSE OF ENERGY MINERALS 23

THICKNESS, 

IN FEET

200

400 

600 

800 

1000

1200 

1400 * 

MAHOGANY 

LEDGE 

OR ZONE

"B" GROOVE

R-6 ZONE 

~~ L-5 ZONE <

R-5 ZONE -

L-4 ZONE

R-4 ZONE '

L-3 ZONE

R-3 ZONE *.

L-2 ZONE

R-2 ZONE <

L-1 ZONE

R-1 ZONE <

ORANGE ZONE

(Zone of low electrical

resistivity that

includes the orange

marker)

The uppermost and most widespread rich oil-shale zone 

in the Piceance and Uinta basins. The top of the saline 

aquifer is in the lower one-third of the Mahogany zone

Represents a major decrease in size of Lake Uinta just prior 

to the deposition of the Mahogany zone

Nahcolite and halite have been leached from this zone 

in most of the Piceance basin

Brecciated oil shales in this zone represent intervals where 

nahcolite and (or) halite beds have been leached. Bedded 

nahcolite and halite are preserved in small areas

One of the richest oil-shale zones in the Piceance basin. 

Also contains the greatest resource of nahcolite of any 

zone. The uppermost significant content of dawsonite 

is found in this zone

Richest oil-shale zone in the center of the Piceance 

basin Contains moderate amount of nahcolite and 

a large amount of dawsonite

Zone containing the greatest amount of dawsonite

Contains three of the most widespread, thick, disseminated nahcolite zones in the basin

Lowest zone containing significant amounts of nahcolite and 

dawsonite

"Blue Marker", top of the Garden Gulch Member. Base of 

saline deposition

Rich oil shale in dominantly clay matrix

Clay-shale zone containing no oil shale

Rich and lean oil-shale zones in part of the Green River Formation in the Piceance basin (fig. 16).
24 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Three samples of oil shale of different grade: Lean sample at center, medium-grade sample on left, high-grade

sample on right (fig. 17).

MINING AND EXTRACTION METHODS 

MAY DEPEND ON THE OIL-SHALE 

RESOURCE AND OVERBURDEN

The methods used to develop oil shale probably will depend on the grade and thickness of the oil shale and on the 

thickness of the overburden. One might assume that oil 

shales are thickest and richest at the depositional center and 

that the thickness of overburden above the Mahogany zone 

is approximately the same near the margins and the center 

of the basin. However, although the shales are thicker and 

richer at the center of the basin, the overburden is also 

generally thicker there because the shale dips toward the 

center at a steeper angle than the topography.

The relation of overburden to the thickness and richness 

of oil shale determines the most economic extraction 

method. Conventional underground mining and surface 

retorting are planned for the relatively thin but rich oil shale 

underlying the privately owned land in the southern part 

of the basin. Mine entry is possible from the well exposed

outcrop of the Mahogany zone along the deeply dissected 

canyons of Roan and Parachute Creeks.

Farther to the north, where the oil shale is thicker and 

richer, the overburden in much of the area is more than a 

thousand feet thick. Oil-shale zones several hundred feet 

thick may be developed using underground mining or a 

modified in situ retort extraction method.

A U-shaped area of 100 square miles containing a resource 

of more than 100 billion barrels of oil may be amenable to 

surface mining. The east limb of the U is along Piceance 

Creek in Tps. 1 and 2 S., R. 97 W. The west limb parallels 

the west margin of the basin in T. 1N., R. 99 W., and Tps. 

1 and 2 S., R. 99 W. The two limbs are connected at T. 2 

S., R. 98 W. In most of this area the shale-oil resource is 

more than 1 million barrels per acre in shale that averages 

25 or more gallons per ton. The waste-to-ore ratio is less 

than 1:1 in much of the area.

The development of oil shale is discussed in greater detail 

in the chapter "Development of the oil shale and associated 

minerals."
STOREHOUSE OF ENERGY MINERALS 25

Sample of nahcolite from Piceance basin. Finely laminated bands (arrows) are included oil shale (fig. 18).

THE OWNERSHIP OF OIL-SHALE MINERAL 

RIGHTS HAS CHANGED OVER THE YEARS

Oil shale, coal, tar sands, crude oil and gas, and various 

sodium minerals on Federal lands are leasable under provisions of the Mineral Leasing Act. Before 1920, oil shale was 

a locatable mineral and claims could be staked. From 1900 

to 1920, hundreds of thousands of acres of oil-shale land 

was staked by prospectors swarming the hills of northwest 

Colorado, northeast Utah, and southwest Wyoming. Many 

of these claims were patented between 1900 and 1960, and 

were sold to industry by the original claimants or their heirs.

Since the early 1960's, the Federal government has not 

patented any oil-shale claims because title to many mining 

claims is under litigation. Prior to 1916, homesteaders along 

the valleys of Piceance Creek and its major tributaries acquired both mineral and surface interests. Private lands purchased by industry during recent years form a band about 

one-fourth to one-half mile wide and 1 to 20 miles long, 

winding along the stream valleys in an area predominantly 

of public domain.

REFERENCES

Austin, A. C., 1971 (1972), Structure contours and overburden on the top 

of the Mahogany zone, Green River Formation, in the northern part of 

the Piceance Creek basin, Rio Blanco County, Colorado: U.S. Geological 

Survey Miscellaneous Field Studies Map MF-309.

Bradley, W. H., 1931, Origin and microfossils of the oil-shale of the Green 

River Formation of Colorado and Utah: U.S. Geological Survey Professional Paper 168, 58 p.

Cashion, W. B., and Donnell, J. R., 1972, Chart showing correlation of 

selected key units in the organic-rich sequence of Green River Formation, Piceance Creek basin, Colorado, and Uinta basin, Utah: U.S. 

Geological Survey Oil and Gas Investigations Chart OC-65.

Donnell, J. R., 1961, Tertiary geology and oil-shale resources of the 

Piceance Creek basin between the Colorado and White Rivers, 

northwestern Colorado: U.S. Geological Survey Bulletin 1082-L, 

p. 835-891.

Hornbaker, A. L., Holt, R. D., and Murray, D. K., 1976, 1975 Summary 

of coal resources in Colorado: Colorado Geological Survey Special 

Publication No. 9, 17 p.

Hite, R. J., and Dyni, J. R., 1967, Potential resources of dawsonite and 

nahcolite in the Piceance Creek basin, northwest Colorado, in Fourth 

Oil Shale Symposium: Colorado School of Mines Quarterly, v. 62, no. 

3, p. 25-38.
26 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

R 1 00 W 1 08°30' .__R£IW R Eg W. P "5 W_108_W _," _?4W.. R93W

OVERBURDEN THICKNESS 

IN FEET

500 THOUSANDS OF 

BARRELS OF 

SHALE OIL PER - 

ACRE OF LANDFor oil shale 

averaging 25 

gallons per ton

f

or more

15 MILES

10 15 KILOMETERS

Total shale-oil resources and overburden thickness above Mahogany zone (fig. 19)
R100W 10B°30'

STOREHOUSE OF ENERGY MINERALS

R98W R97W R96W R95W 10BW R94W

27

R93W

EXPLANATION

PUBLIC LAND 

PATENTED/FEE LAND

15 MILES

I

\ 

15 KILOMETERS

Mineral ownership in the Piceance basin (fig. 20).
28 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Mullens, M. C., 1976, Structure contours and overburden on the top of 

the Mahogany zone, Green River Formation in the southern part of the 

Piceance Creek basin, Rio Blanco and Garfield Counties, Colorado: U.S. 

Geological Survey Miscellaneous Field Studies Map MF-746.

Rocky Mountain Association of Geologists, 1974, Guidebook to the energy 

resources of the Piceance Creek basin, Colorado, 25th Annual Field Conference: Denver, Colo., 302 p.

Oil-shale and associated mineral development require an 

understanding of geology, hydrology, mining, mineral extraction, mineral transportation, and land reclamation. A 

brief description of these subjects follows.
DEVELOPMENT OF THE OIL SHALE AND ASSOCIATED MINERALS

By G. A. MILLER

OIL-SHALE DEVELOPMENT IN 

PICEANCE BASIN BEGAN ABOUT 1900

Before 1900, local Ute Indians recognized the unusual 

nature of oil shale, and they termed it "the rock that burns." 

Eventually the occurrence of oil shale in the Piceance basin 

was noted by settlers from the East. Oil shale reportedly was 

burned as a frost deterrent in fruit orchards at Palisade, 

Colo. (about 11 miles northeast of Grand Junction), as early 

as 1905. Mining claims were filed on oil-shale outcrops 

beginning about 1910. The U.S. Bureau of Mines and the 

U.S. Geological Survey began scientific studies of the 

deposits during the period 1912-14, and National recognition of the size and potential of the deposit in the southern 

part of the basin led to the establishment of the Naval Oil 

Shale Reserves in Colorado and Utah in 1916.

From 1915 to 1920, thousands of acres in the outcrop 

areas, mostly along Parachute and Roan Creeks, were claimed under the 1872 mining law. Claiming stopped with 

passage of the 1920 Minerals Leasing Act, which provided 

for leasing of oil shale. At that time, the rich, thick oil-shale, 

nahcolite, and dawsonite deposits in the middle part of the 

basin were unknown.

Many small experimental retort operations were tried near 

De Beque, Colo., from 1918 to 1922, but probably fewer 

than a thousand barrels of shale oil were produced. Promotional schemes apparently were common in the area, 

some purporting to recover gold, silver, and other valuable 

materials along with the shale oil.

Work by the U.S. Bureau of Mines on oil shale included 

laboratory studies from 1919 to 1924 and mining and retorting at the Rulison site near Rifle, Colo., from 1925 to 1929. 

Approximately 1,500 barrels of shale oil were produced. 

This early development ended when large petroleum fields 

were discovered in Texas and California, and Federally 

owned oil-shale lands were withdrawn from leasing in 1930.

Public Law 78-290, the Synthetic Fuels Act (1944), 

authorized the U.S. Bureau of Mines to conduct research 

and development for synthetic fuels, including oil shale. The 

Bureau began construction that same year at the Anvil 

Points site, a few miles east of the old Rulison site". This 

research, which focused on mining and retorting methods, 

continued until 1956.

During the 1950's, 1960's, and 1970's several research programs experimented on a small scale with shale-oil and

mineral-extraction methods, including in situ retorts and 

aboveground retorts. A proposal during the late 1960's to 

use heat from an underground atomic explosion to recover 

shale oil was not tried by onsite experiments, however. In 

1968, a leasing attempt by the U.S. Department of the Interior resulted in rejection of all bids for three tracts in the 

Piceance basin. Onsite research for in situ recovery methods 

began on private land in the Logan Wash area of southern 

Piceance basin in 1972.

In 1974, after the preparation of an environmental impact statement, the Department of the Interior leased oilshale tracts C-a and C-b. The bid prices were surprisingly 

high, primarily because of expensive world oil prices (the 

C-a bid price was about $210 million and the C-b bid price 

was about $118 million). The prototype program had four 

goals:

1. To provide a new source of energy to the Nation,

2. To insure the environmental integrity of the affected 

areas,

3. To permit an equitable return to all parties, and

4. To develop management expertise.

Development on Federal tracts C-a and C-b began in 1978, 

after collection of predevelopment data and preparation of 

a development plan, and continues to date.

Also in 1974, a consortium of several companies began 

testing aboveground retorting techniques at the Anvil Points 

facility of the U.S. Bureau of Mines. In 1980-81, development of two oil-shale facilities began on private land in 

Parachute Creek valley, and preliminary plans were announced for similar developments in Roan Creek valley.

VARIOUS MINING METHODS ARE PROPOSED

The operators at most sites in the Piceance basin propose 

to mine oil shale at a larger scale than ever before attempted. 

The project life of mines may be decades or centuries, the 

saleable products are worth trillions of dollars, and the 

volume of waste generated may be as much as millions of 

cubic yards per day.

In the northern part of the basin the associated minerals 

nahcolite and dawsonite may be mined in conjunction with 

the oil shale if a developer can acquire a multimineral lease. 

This type of lease has not been offered previously.

29
30 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

10B°30' 10BW

15 MILES

0 5 10 15 KILOMETERS

Modern and historic sites related to oil-shale development (fig. 21).
DEVELOPMENT, OIL SHALE AND ASSOCIATED MINERALS 31

Spoil pile of retorted shale from the experimental retort of the U.S. Bureau of Mines, 1925-29 (fig. 22).

Mining of the oil shale in a single operation is desirable 

because:

1. Resource recovery probably will be greater with a 

single mining operation;

2. Secondary recovery or a second mining operation in 

such a large, thick deposit is inefficient and expensive; 

and

3. Mine drainage, required at most sites, probably would 

have to be repeated during a second mining operation.

Mining methods generally are classified as either surface 

mining or underground mining. In surface mining the entire mine is "open to the sky." Proposed surface mines in 

the Piceance basin typically are migrating open pits, in which 

mined and processed material is used to backfill the abandoned pits. Because oil-shale deposits typically are covered 

by barren rock, the thickness of the overburden rock in comparison to the thickness and grade of the underlying oil shale 

is an important consideration in planning such mines. The 

thickness of the overburden and oil shale vary considerably 

because of topography and geologic structure. (See map, 

fig. 19.)

Conditions are considered favorable for surface mining 

in a large area in the west-central part of the basin where 

the ore is thick and the overburden is thin. Several 

preliminary feasibility studies on surface mining have recommended the area near tract C-a as a logical place to begin 

a surface mine. The top of the rich oil shale lies at or within 

500 feet of the land surface, and the mineable thickness of 

oil shale locally exceeds 1,000 feet.

The general sequence for surface mining would be:

1. Mine drainage, if required.

2. Removal of overburden and stockpiling soil or alluvial 

material for later use in reclamation.

3. Widening and deepening the open pit to the bottom 

of the ore, and starting shale-oil production.

4. Extension of the pit (migration) into unmined areas. 

5. Backfilling the pit with overburden and waste (when

a sufficient area is open).

During overburden removal, the waste material is placed 

away from the mining area. Oil-shale retorting can begin 

during pit excavation. The waste material, including retorted 

shale, continues to be placed away from the mining area
32 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

:

. Tract C-a 

Oil-shale plants at Federal lease tracts C-a and C-b (fig. 23 above and facing page).

during pit excavation, but is backfilled in the mined-out pit 

during pit migration. During the entire operation, topsoil, 

poorly developed soil, or alluvium suitable for land reclamation can be separated and stored for future use. Where conditions are favorable, surface-mining techniques allow 

recovery of most of the oil shale, except under the sloping 

pit walls.

The underground mining method commonly considered 

for oil shale is the room-and-pillar mine, in which tunnels 

are dug into the oil shale, either from surface outcrops on 

canyon walls or from shafts, and large rooms are excavated 

using a single- or multiple-level advance as the ore is mined. 

The rooms are separated by pillars of unmined oil shale that 

support the mine roof. Subsidence of the land surface may 

occur during and after underground mining. Subsidence 

results mostly from the mining and drainage that reduce support of the overlying material. Subsidence can be minimized 

by injecting water into abandoned mines and by backfilling mined-out zones with waste rock and processed shale.

However, such injection and backfilling increases development costs. Tradeoffs of allowable subsidence against 

resource recovery are probable because the likelihood and 

magnitude of subsidence increases as resource recovery increases. In those regions where subsidence would be 

undesirable or damaging, mining may need to be restricted.

In sections of oil shale that are only 60-80 feet thick, 

room-and-pillar mining methods can recover as much as 60 

to 70 percent of the resource, and more if the pillars are partly mined during the final stages. In the thicker layers of oil 

shale that occur beneath most of the Piceance basin, roomand-pillar mines can recover only 10-30 percent of the 

resource.

Other underground mining and extraction methods, such 

as block caving and longwall mining methods, would 

recover a higher percentage of the resource, but are presently 

too costly. New underground methods may be designed to 

more economically recover a high percentage of the 

resource.
DEVELOPMENT, OIL SHALE AND ASSOCIATED MINERALS 33

Tract C-b

OIL SHALE CAN BE PROCESSED IN 

ABOVEGROUND AND IN SITU RETORTS

Proposals for oil-shale processing include a variety of 

retorts operated aboveground, and several types of underground in situ retorts and modified in situ retorts. All 

methods of retorting heat the shale to a minimum temperature of about 900 °F, at which most retorting occurs.

The different types of aboveground retorts have several 

features and functions in common:

1. All require that the oil shale to be retorted is crushed 

to a size ranging from less than Vi inch to as much as 

6 to 10 inches.

2. All have mechanisms to move the ore continuously 

through the retort.

3. All incorporate features to control the temperature and 

rate of movement through the retort.

4. All provide for separation of shale oil, water, and gas 

products.

5. All are sensitive to the richness of the feedstock; they 

cannot process shale efficiently below a minimum grade.

The heat in aboveground retorts is supplied either directly, by burning some of the oil shale in the retort, or indirectly, by mixing preheated gases or solids with the oil shale 

to achieve retorting. The direct methods burn the carbon 

in retorted shale after the hydrocarbons have been driven 

off by heat. The indirect, or externally heated, methods use 

a supply of gas or liquid fuels either brought to the site or 

diverted from the retort products. Some indirect methods 

obtain process heat by burning residual carbon in retortedshale fragments in a separate furnace.

In situ and modified in situ processing techniques are 

batch methods designed to minimize the mining, transporting, crushing, and other operations associated with aboveground retorting. Several methods that heat the shale in 

place have been proposed and attempted. In situ burning 

of shale and residual carbon, injection of hot steam or hot 

gases, and heating by electricity or microwaves have been 

tested in laboratory studies and onsite. Steam is generated 

at land surface and injected into wells open to the oil shale, 

or injected into a modified in situ retort. Hot gases may be 

either produced at a surface facility or produced by the burning of residual carbon and some oil shale in a directly
34 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Initially the ore is mined 

in a large open pit

Oil shale

<?;' :' : so".. 1

Overburden

Oil shale

Soil-'. 

Overburden

Backfilled 

waste material

Oil shale Oil shale

Surface mining using a migrating open pit (fig. 24).
DEVELOPMENT, OIL SHALE AND ASSOCIATED MINERALS 35

ACCESS TO MINE THROUGH VERTICAL SHAFT

ACCESS TO MINE THROUGH ADIT

Underground mining using room-and-pillar method (fig. 25).
36 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Samples of crushed but unretorted oil shale (left) and retorted oil shale (right) from field tests, Rulison site, 1928 (fig. 26).

heated, modified in situ retort. Proposed electrical-heating 

methods include resistance and induction (microwave) 

heating.

Significant differences distinguish the commercial products and by-products of one retorting method from another. 

The differences are related to the temperature during retorting, and whether direct or indirect methods are used. Direct 

retorting methods tend to operate at much higher temperatures than the minimum required for retorting. The burning is accomplished by injecting air into the retort, and the 

resulting high temperatures tend to cause calcining (conversion to calcium and magnesium oxides) of the carbonate 

minerals, calcite and dolomite, in the oil shale.

The fuel products resulting from retorting are shale oil 

and a hydrocarbon (synthetic natural) gas. The hydrocarbon gas is greatly diluted with nitrogen from the inlet air 

and with dioxide from combustion of carbon and from the 

calcining of the carbonate minerals. The retorted shale 

typically contains a large percentage of calcium and 

magnesium oxides. Heating at temperatures greater than 

2,000°F for a long period causes some of these solid-state 

oxides to react with other minerals to produce silicate 

minerals that resemble those in igneous rocks.

Indirect retorting methods typically operate at the 

minimum temperature necessary to achieve efficient retorting. The methods also produce shale oil and hydrocarbon 

gas that is not diluted by nitrogen and carbon dioxide 

because air is not injected and the retorting temperature is 

below the temperature required for calcining.

WATER DEMANDS FOR OIL-SHALE 

DEVELOPMENT MAY BE GREAT

An oil-shale mine and processing plant will require water 

supplies for various uses. The supplies will be derived from 

some combination of ground water drained from mines, 

deep ground-water reservoirs, surface-water diversions, surface reservoirs, and imported water. The water will be consumed during operations for:

1. Dust control;

2. Drilling;

3. Steam generation for various industrial processes, including retorting and product upgrading;

4. Exhaustion of moisture-laden mine-ventilation air to 

the atmosphere;
DEVELOPMENT, OIL SHALE AND ASSOCIATED MINERALS 37

5. Power generation;

6. Cooling;

7. Moistening and cooling retorted shale;

8. Reclaiming and revegetating retorted shale and disturbed lands; and

9. Removal of impurities from evolved gases.

The amount of water required is not well defined, but 

most estimates range from 1 to 4 barrels of water per barrel 

of shale oil produced. The wide range is related partly to 

the different requirements for different oil-shale mining and 

retorting processes and partly to the uncertainties in projecting water uses based on small-scale industrial experience. 

Industrial water requirements for various levels of shale-oil 

production and volumetric ratios of water to oil can be 

determined. The average rate at which the United States imported crude oil in 1980, 5.16 million barrels per day, is 

shown in the graph for comparison.

Estimates of the increase in municipal water use are based 

on projections of population growth that will accompany 

large-scale development of oil shale. A 50,000-barrel-perday mine and plant may employ about 3,000 people. The 

total population may be three to five times larger than the 

work force. Therefore, a 50,000-barrel-per-day plant may 

support a population of 9,000 to 15,000 people. Assuming 

the water requirement is 100 gallons per person per day, the 

graph relates municipal water requirements to different levels 

of shale-oil production and population per plant. The 

municipal water requirements are less than the industrial 

water requirements for shale-oil production, as indicated by 

the different vertical scales on the graph of water 

requirements.

Additional discussions of water supplies for oil-shale 

development are found in the chapters "Hydrologic system 

of the Piceance basin" and "Benefits, requirements, and effects of different levels of oil-shale development."

MINERAL TRANSPORTATION WILL DEPEND 

ON THE VOLUMES AND TYPES OF PRODUCTS

A commercial oil-shale industry in Piceance basin will 

produce large volumes of shale oil and potentially large 

volumes of by-products such as sodium and aluminum 

minerals, ammonia, sulfur, hydrocarbon gas, liquified 

petroleum gas, and coke. Other potential products are 

nitrogen and carbon dioxide, which are the main waste gases 

from some high-temperature retorts. A significant activity 

therefore will be the transportation of mineral products to 

markets or to existing conveyances, which are typically hundreds of miles from the mines and plants. During the early 

stages of a developing industry, the volumes of products 

are small and probably will be shipped by truck and 

railroads.

However, the volume of most products will need to be 

reduced because transportation is so expensive. Most shale 

oil probably will be processed to be equivalent in composition to the crude oil supplied to oil refineries. Pipelines are 

probably the most practical method of moving shale oil, 

hydrocarbon gas, liquified petroleum gas, and ammonia. 

Proposed pipeline routes for moving shale oil from the basin, 

initially connecting with existing pipe lines, are based on 

rates of production from individual sites ranging from 10,000 

to 100,000 barrels per day. Proposed common-carrier routes 

extend southwest to Lisbon Valley, Utah, northwest to 

Rangely, Colo., and northeast to the area between Casper 

and Guernsey, Wyo. Because the existing common-carrier 

pipelines at these sites have a limited capacity, transportation of additional large volumes will not be possible. 

Separate pipelines, perhaps along some of the same corridors, would be necessary for transport of large amounts 

of ammonia, hydrocarbon gas, and liquified petroleum gas.

Sulfur, coke, and sodium and aluminum minerals probably will be shipped by railroad. A major railroad line connecting Denver and Salt Lake City runs along the south edge 

of the basin. Preliminary studies indicate that it may be feasible to extend a line northward from Rifle, Colo., down the 

valley of Piceance Creek, and to the central part of the basin.

RECLAMATION WILL BE REQUIRED FOR 

ABANDONED MINES, SPOIL PILES OF 

RETORTED SHALE, AND IN SITU RETORTS

A major concern of governments, private interests, and 

the general public is the effect of large scale oil-shale development on the land and water resources in the area. Such 

development, involving perhaps a dozen or more mines, 

could eventually affect the land surface, underlying rocks, 

and water of the entire basin.

ABANDONED MINES

Abandoned mines need to be left in a stable condition in 

order to reduce the subsidence of the land surface and to 

avoid the disruption of surface-water and ground-water flow 

systems. Long-term continuous subsidence is likely above 

large mines, especially where the overburden is thin or weak.

Large-scale subsidence also would restrict uses of the land 

surface and possibly would cause damage to streams, canals, 

reservoirs, and pipelines. In many underground mines 

throughout the world, subsidence has been successfully controlled by backfilling the old mine workings with waste 

material, which provides partial support for the pillars and 

the mine roof. At an abandoned oil-shale mine, perhaps 

60-80 percent of the mined-out materials (waste rock and 

retorted shale) could be backfilled in the mine. The benefits 

of backfilling are:
OJ 

00

WATER REQUIREMENTS, IN THOUSANDS OF ACRE-FEET PER YEAR

§.

00 

XI

WATER REQUIREMENTS, IN THOUSANDS OF ACRE-FEET PER YEAR

M Ol

8 8

WATER REQUIREMENTS, IN CUBIC FEET PER SECOND WATER REQUIREMENTS, IN CUBIC FEET PER SECOND
DEVELOPMENT, OIL SHALE AND ASSOCIATED MINERALS 39

SHALE OIL PRODUCTION, IN BILLIONS OF BARRELS PER YEAR 

1 2

2 34567 

SHALE OIL PRODUCTION, IN MILLIONS OF BARRELS PER DAY

Retorted shale production (fig. 28).

1. Subsidence of the land surface would be reduced.

2. Additional oil-shale and other mineral resources could 

be recovered by mining the support pillars in 

underground mines.

3. The volume of retorted shale for disposal on the land 

surface would be decreased.

The disadvantages of backfilling are:

1. Mineral-development costs would be increased, unless 

the increased costs could be offset by increased 

productivity.

2. The retorted shale that was used as backfill could 

adversely affect the quality of ground water because 

it contains readily soluble materials. The problem 

could be minimized by reducing the teachability of the 

retorted shale.

Injection of water into abandoned mines may also reduce 

subsidence by providing support for the overlying materials. 

However, a water supply of suitable quality may not be 

available.

SPOIL PILES OF RETORTED SHALE

Large volumes of retorted-shale waste material will be 

produced by aboveground retorting. The volume produced 

depends on four main factors:

1. The total shale-oil production,

2. The average yield of the ore processed,

3. The density of the retorted shale, and

4. The particle size of the retorted shale.

The production of retorted shale for various rates of production and ore yields can be estimated, presuming that the 

retorting process consumes 15 percent of the original weight 

of the untreated shale, and the retorted shale is compacted 

to weigh about 90 pounds per cubic foot. Large volumes 

and weights of retorted shale will accumulate rapidly from 

high production rates and from development of lean ore.

Proper disposal of retorted-shale waste requires that the 

material be stable for many years. Retorted shale is saline 

and alkaline, contains few plant nutrients, and is more credible than the original rock. The slow but inevitable processes
40 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Revegetation of retorted shale at test plots. A, Instrumented plot operated by Union Oil Co near Parachute Creek. 8, Test plots operated 

by Colorado State University between Yellow Creek and Ryan Gulch. Twelve inches of topsoil was added to plot on left; none was 

added to plot on right (fig. 29 above and facing page).

of weathering, erosion, leaching, and transport in streams 

eventually will allow the waste materials to migrate 

downstream in the Colorado River basin. The present concern is to ensure that the rate of waste removal by these processes is acceptable.

Nearby canyons and mesas have been proposed as sites 

for disposal of retorted shale from underground or surface 

mines. Sites near the heads of canyons appear to be acceptable because surface runoff from small upstream areas is 

limited and the erosion potential is low. Plans and limited 

onsite tests for the reclamation of spoil piles include removing and stockpiling soil or alluvial materials from the dump 

site, compacting retorted shale as it is placed on the pile, 

contouring the surface to minimize erosion, and covering 

the pile with soil and soillike material.

Uncertainties in the details of the optimal procedures for 

the reclamation of spoil piles of retorted shale include the 

amount of compaction required, the structural stability of 

the retorted-shale pile, the thickness and character of the

cover materials, the potential for migration of soluble salts 

from the retorted shale upward into the plant-root zone, the 

maximum slope that is stable and can be revegetated, the 

degree to which rainfall and snowmelt will infiltrate and 

leach soluble materials from the retorted shale, the optimum 

vegetation types to achieve a permanent cover, and the need 

to irrigate the newly planted surface. Many short-term field 

tests of the physical and chemical stability of small areas 

of reclaimed retorted shale have met with various degrees 

of success. In general, the test results show a need for:

1. Compaction of the retorted shale to decrease its 

permeability,

2. Emplacement of 3 to 18 inches or more of soil or 

alluvial material cover,

3. Emplacement of coarse material between the retorted 

shale and the soil or alluvial material cover to decrease 

upward migration of soluble salts and discourage root 

growth, and

4. Maximum slopes of 4:1 to 5:1 for the surface of the pile.
DEVELOPMENT, OIL SHALE AND ASSOCIATED MINERALS 41

None of the onsite tests has been of adequate areal extent 

or duration to provide design details for the large pile that 

would result from commercial development.

Regardless of the methods used, a reclaimed spoil pile 

needs to have the following characteristics:

1. Plant growth must be present to decrease erosion, provide forage for livestock and wildlife, and preserve the 

natural landscape.

2. The erosion rate should be low enough that the rate 

of soil transport away from the pile is equal to or less 

than the rate of weathering and conversion of the 

underlying retorted shale to plant-supporting soil. Erosion rates measured locally in the Piceance basin have 

been as high as 0.1 inch per year.

3. The ability must exist to either convert the harmful 

constituents in retorted shale to harmless material, or 

to cause downward migration of the harmful constituents into the pile and immobilize them below the root 

zone.

Additional discussion of spoil piles is found in the chapter 

"Chemical effects and control of leachates from oil-shale 

spoil piles."

At surface mines, a variety of materials removed from 

the mine is available for reclamation by backfilling, including soil, alluvium, weathered rock, overburden rock, 

lean oil shale, and retorted shale. In backfilled zones, some 

subsidence and adverse effects on water quality may occur; 

the subsidence probably is less than in underground mined 

areas because the reclamation of open-pit mines can be more 

easily controlled. Many options are available for placement 

and control of the waste materials in a mined-out area. For 

example, the characteristics of the hydrologic system that 

develops in and on a backfilled pit can be controlled partly 

by design. These characteristics include surface runoff, 

ground-water recharge, ground water in storage, waterquality effects, erosion, and plant-growth potential for 

specific plant communities.

Retorted shale can be compacted in a bottom layer of low 

permeability that is covered by a more permeable layer of 

waste rock and overburden that is in turn overlain by a layer 

of sandy and silty soil, alluvial material, and topsoil. The 

surface can be sculpted into gentle slopes and revegetated 

to minimize erosion. Assuming that the present climatic conditions continue, this design would tend to minimize surface runoff, increase soil moisture, increase ground-water
42 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

recharge, and minimize erosion. An alternative placement 

of backfilled material could increase surface runoff and 

decrease ground-water recharge. Other designs are also 

possible.

IN SITU RETORTS

In situ and modified in situ retorting methods cause special 

disposal problems because the retorted shale remains 

underground, and typically the retort is much more permeable than the surrounding rock. The mass of retorted shale 

that is abandoned in modified in situ retorts, such as that 

produced at an experimental site in Logan Wash, Colo., and 

at Federal lease tract C-a, presumably is permeable and contains readily leachable minerals. Laboratory tests and limited 

onsite tests indicate that the initial leachate from such retorts 

is alkaline and contains several tens of thousands of 

milligrams of dissolved salts per liter of water. This leachate 

is not a desirable addition to the local ground-water system, 

and several studies have been conducted on how to minimize 

its impact. Potential methods to control or minimize the 

leachate include:

1. Deliberate leaching of the retort prior to abandonment, 

collecting the leachate at the surface, and evaporating 

the leachate to produce a smaller, more manageable 

volume;

2. Grouting the retort by filling the open spaces between 

shale blocks with a cement slurry that is prepared using 

retorted shale;

3. Placing a grout curtain around the retort to isolate toxic substances from the ground water;

4. Creating a hydraulic bypass to minimize the groundwater flow through the retorted shale; and

5. Controlling retort conditions such as temperature in 

order to reduce the amount of material produced that 

could be deleterious to ground water.

Although all of the above methods would decrease the 

leachate problem, none has been evaluated using onsite tests.

Additional characteristics of in situ retorts are described in 

the chapter "Chemical effects and control of wastes from 

in situ retorts."

Little is known of the nature of shale that is retorted in 

situ under low temperatures, by steam, hot gas, or electromagnetic energy. However, the removal of the shale oil 

from the rock would tend to increase its permeability and 

would expose fresh surfaces of rock to leaching by ground 

water.

REFERENCES

Ashland Oil, Inc., and Occidental Oil Shale, Inc., 1977, C-b shale oil project, modification to detailed development plan, 89 p.

Ashland Oil, Inc., and Shell Oil Co., 1976, C-b shale project, detailed 

development plan and related materials, 2 v,

Colder Associates, 1977, Water management in oil shale mining: U.S. 

Bureau of Mines Open-File Report 278, 2 v.; prepared under U.S. Bureau 

of Mines contract T0265019.

Gulf Oil Corp., and Standard Oil Co. (Indiana), 1976, Detailed development plan, tract C-a, 3 v.

____1977, Revised detailed development plan, tract C-a, 3 v.

Hendrickson, T. A., compiler, 1975, Synthetic fuels data handbook: 

Denver, Cameron Engineers, Inc., 297 p. and appendix.

Miller, G. A., 1981, Water availability and requirements for western oil 

shale development, in Environmental and economic considerations in 

energy utilization: Ann Arbor, Mich., Proceedings of the Seventh National Conference on Energy and the Environment, p. 44-49.

Russell, P. L., 1979, History of western oil shale: East Brunswick, N.J., 

The Center for Professional Advancement, 152 p.

U.S. Bureau of Land Management, 1975, Final environmental impact statement, proposed development of oil shale resources by Colony Development Operation in Colorado, 2 v.

U.S. Bureau of Reclamation, Upper Colorado Region, 1974, Alternative 

sources of water for prototype oil shale development, Colorado and Utah, 

115 p.

U.S. Department of the Interior, 1973, Final environmental statement for 

the prototype oil shale leasing program, 6 v.

Mine stability and the occurrence of ground water are 

partly controlled by the joint patterns of the Green River 

Formation. These joint patterns and their significance are 

discussed in the following chapter.
RELATIONS AMONG THE GEOLOGIC, HYDROLOGIC, AND 

GEOCHEMICAL CHARACTERISTICS OF THE BASIN

SYSTEMATIC JOINTS WITHIN OIL SHALES AND ASSOCIATED ROCKS

OF THE GREEN RIVER FORMATION

By EARL R. VERBEEK and MARILYN A. GROUT

Nearly all rocks exposed at Earth's surface contain 

numerous joints naturally occurring fractures that break 

a once-solid rock mass into a series of smooth-sided blocks. 

Sizes of such joint-bounded blocks span a broad range; 

blocks from one-half to several feet on a side are typical of 

many areas, including the Piceance basin. A small outcrop 

of rock thus may contain hundreds of joints, and a mine may 

contain millions yet joints in the Piceance basin received 

only scant attention until 1979-81 when the joint sets described here were identified. Extended studies of these joints 

are described in reports listed in the references at the end 

of this chapter. The importance of joints to the oil-shale industry stems from two facts:

1. Joints are the primary conduits through which ground 

water flows beneath the basin.

2. Joints impair the stability of any manmade cut in rock, 

whether at the surface or underground.

HYDROLOGIC ASPECTS OF JOINTS

Processing of oil shale will create increased demands for 

water in the Piceance basin. Costly importation of water from 

outlying areas could be minimized if nearby sources of 

ground water were identified and tapped. Successful development of the basin's ground-water resources hinges on an adequate understanding of water flow through the various 

regional ground-water reservoirs which are discussed in the 

chapter 'Paleozoic and Mesozoic formations and their potential as ground-water reservoirs." On a more local scale, 

drainage of underground mines and in situ retorts and the 

disposal of waste water from both sources pose their own 

special concerns. Drainage of a mine area, for example, might 

reduce the yield of nearby water wells. Disposal of the water 

by injection could have adverse effects on water quality in 

nearby streams and in wells drilled for drinking water. Here, 

too, an understanding of ground-water flow through fractured rocks is necessary to optimize locations of new wells 

and to predict their effects on existing wells and streams.

The flow of ground water beneath the Piceance basin is 

most conveniently envisioned as taking place through three 

types of openings in rock:

1. Primary voids, which are small pores and hairline 

cracks between individual mineral grains;

2. Secondary voids created by the dissolution of watersoluble minerals by ground water; and

3. Joints, whose opposing walls commonly are separated 

slightly and permit the passage of water.

Primary voids in oil shale transmit water only at exceedingly slow rates, both because the openings are so minute 

and because many of them are clogged with kerogen, the 

solid hydrocarbon that liberates shale oil upon heating. Intact oil shale thus is one of the least permeable rocks in 

northwestern Colorado. Secondary permeability has resulted 

wherever ground water has removed the water-soluble 

minerals nahcolite and halite, leaving behind a highly porous 

oil-shale rubble. Such rubble transmits water freely but is 

of restricted occurrence within the Green River Formation 

because most of the formation lacks significant quantities 

of water-soluble minerals. Joints, in contrast, occur 

throughout the Green River Formation, where they increase 

permeability and storage and influence flow paths of ground 

water. Of the three general types of water-transmitting openings in the oil shales, joints are the principal conduits for 

ground-water flow at shallow to intermediate depths. Accordingly, local joint networks can be expected to affect the 

yield of water wells, the way in which mine drainage affects 

wells and streams, and the suitability of other wells for injecting waste water into aquifers. Water movement within 

the fractures and pores of the aquifers associated with oil 

shale also is discussed in the chapter "Hydrologic system of 

the Piceance basin."

ENGINEERING ASPECTS OF JOINTS

The success of mining oil shale by any method will depend to some extent on an adequate understanding of the 

joint network at the site. Where shale oil is to be recovered 

from an in situ retort, for example, preexisting fractures will:

1. Affect the ease of properly rubblizing the rock in the 

retort and affect the size and shape of the resultant 

blocks;

2. Affect hydraulic connection between the retort and 

recovery wells for hydrocarbons liberated from the 

burning shale; and

3. Control the transport, by ground water, of leachates 

from the retorted shale.

45
46 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Joints in underground mines provide numerous entries for 

water and hazardous gases into the mine workings. Highcapacity pumps and added ventilation equipment may be 

necessary where workings intersect zones of closely spaced 

joints. Rock stability may be a problem in these same areas; 

for example, pillars may have only a fraction of their design 

strength if they contain large, inclined joints. However, the 

cost of excavating rock in some underground mines may be 

decreased if the mine is designed to take maximum advantage of the natural fracture network.

Joints at the land surface are of lesser consequence; their 

chief effect is to reduce the stability of manmade cuts in rock, 

locally to the point of collapse. Small rockfalls of several or 

more joint-bounded blocks are common along roadcuts, 

especially during the cooler months when alternate freezing 

and thawing of water within joints wedge the rock apart. 

Collapse of larger volumes of rock is possible wherever the 

rock is weakened by closely spaced joints, particularly where 

many joints are parallel to or dip toward the free face of an 

excavation. Local modifications of the design of open-pit 

mines may be advisable where fracture patterns could jeopardize safety.

PRELIMINARY STUDIES OF JOINTS INDICATE 

SYSTEMATIC PATTERNS THAT ARE 

SIGNIFICANT TO HYDROLOGY AND MINING

Joints of diverse orientation within the same exposure are 

usual and commonly impart to the rock a somewhat chaotic 

or randomly broken appearance. Closer inspection of the 

exposures, however, generally reveals that the orientations 

of the joints, although diverse, are also highly systematic 

that is, that the rock is fractured in a definite pattern that 

can be recognized and traced from one exposure to another. 

Joints commonly occur in sets groups of parallel or nearly 

parallel fractures of similar appearance and presumably common origin. Work is now in progress to determine the relative 

sequence of joint-set development at more than 350 localities, 

to correlate joint sets from one locality to another, and thus 

ultimately to determine the fracture history of the Piceance 

basin in considerable detail. This discussion gives some 

preliminary results from the ongoing study of exposures of 

the Green River Formation in the northern part of the Piceance basin.

Eight sets of joints have been recognized within rocks of 

the Green River Formation in the Piceance basin. Joints of 

each set have characteristic orientations, sizes, spacings, ages, 

surface markings, and mineral coatings, and they can be 

distinguished from joints of other sets by these features. Two 

to four sets of joints, unequally developed, are present in 

most exposures of the Green River Formation. No exposure 

contains all eight sets.

The term joint is restricted by some to those fractures that 

simply have opened slightly. Other fractures along which

slip has occurred, and the opposing walls of the fracture have 

ground against each other, are more properly termed faults. 

However, faults along which the amount of slip is negligibly 

small, less than one inch, commonly are grouped with joints 

for descriptive purposes. We will follow that convention in 

this paper.

Joint sets are here referred to by the letter F (for fracture), 

followed by a subscript that indicates the relative age of the 

set; F1 is the oldest set. Thus, joints of the third period of 

systematic fractures to have formed within the oil shales of 

the Green River Formation are referred to simply as F3 

joints. If two or more sets formed during the same period, 

they will be denoted F3A, F3B, etc. Noteworthy features of 

each joint set are mentioned briefly below and are entered 

in condensed form in table 3. Readers not interested in the 

descriptions of specific sets may wish to skip to the summary section on page 49.

JOINT SETS F1A AND F1B

Joints inclined to the sedimentary layers at angles of about 

50 to 70° were the first systematic fractures to form in parts 

of the Green River Formation. In most places, the F1A and 

F1B joints trend northwest to north, but north north-easterly 

trends have been noted locally. Some of the joints (F1A) dip 

to the northeast or east, whereas others (F1B) dip to the 

southwest or west. The two sets are of the same age; at many 

outcrops it can be shown that F1A and F1B joints developed 

almost simultaneously in the same layer.

The distribution of F1A and FIB joints within oil shales of 

the Green River Formation is patchy. Locally, however, they 

dominate the joint pattern of the oil shales to the virtual exclusion of other sets. A third set, vertical FIC joints, have 

been found in a few places but are so uncommon that they 

will not be discussed here.

The F1A and F1B joints are small-scale normal faults that 

record breakage of the oil shales under the weight of overlying, younger sediments. Beds of oil shale commonly are offset a few tenths of an inch along F1A and F1B joints, whose 

surfaces locally bear minute scratches that formed as the two 

walls of each joint slipped against each other. The slight slip 

of one joint wall relative to the opposing wall opened a series 

of voids along some of the F1A and F1B joints that, as a 

result, are locally important conduits for ground-water flow. 

Entry of water into mine workings and decreased rock 

strength are likely where F1A and F1B joints are closely 

spaced.

JOINT SET F2

West- to northwest trending vertical F2 joints, the dominant fractures of the Green River Formation, are present in 

nearly all outcrops. The F2 joints are the best developed of 

all sets in most exposures and typically are most abundant
SYSTEMATIC JOINTS OF THE GREEN RIVER FORMATION 47

A well-developed set of joints, with an average spacing of about one foot, within moderate-grade oil shales

of the Piceance basin (fig. 30).
48 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

A set of F2 joints in moderately rich oil shales near the mouth of Piceance Creek (fig. 31).

in marlstones and in the lean oil shales. Joint spacings the 

distance between adjacent joints may average 3 inches or 

less in these lean beds, but spacings increase with greater 

richness of the oil shales. Spacings from 1.5 to 5 feet are 

common within many beds of moderate richness; spacings 

of 10 feet or more are typical of the richest beds.

Many F2 joints in surface exposures are open that is, 

the opposing walls of each joint are separated about 1/16 

to 1/8 inch. Evidence for past ground-water movement 

through these open fractures is abundant: the oil shales commonly are bleached (oxidized) to a tan color adjacent to F2 

joints (fig. 30), the joint walls themselves locally are deeply 

pitted and corroded (even in unweathered, manmade exposures), and the walls of some F2 joints are plated with 

calcite precipitated from the circulating ground water. Joints

of other sets are much less open and show only minimal effects of ground-water flow through them. By analogy, 

present-day ground-water flow through bedrock may take 

place mostly along F2 joints at depth. Zones of closely 

spaced F2 joints thus are promising areas for high-yield 

water wells, but the same zones may present problems of 

rapid ground-water flow into underground-mine workings. 

Typical F2 joints have large surface areas, cut several or 

more beds in the vertical direction, and extend laterally for 

tens of feet. The F2 joints are planes of weakness along 

which slabs of rock readily separate. Road cuts with free 

faces parallel to F2 joints may be marginally stable; some 

have already collapsed. The stability of underground excavations may likewise be weakened by large and closely 

spaced F2 joints.
SYSTEMATIC JOINTS OF THE GREEN RIVER FORMATION 49

JOINT SETS F3A AND F3B

The F3A and F3B joints appear to be restricted to the 

southern part of the Piceance basin; they have not yet been 

found in rocks exposed in the drainage areas of Piceance 

and Yellow Creeks. Little is known of these joints because 

they have been studied within only a small area of the Roan 

Plateau. Their characteristics as outlined here thus may not 

be typical of these joints in other areas.

The F3A and F3B joints are large fractures; surface areas 

of more than 100 square feet are common. Like the F1A and 

F1B joints, they appear to have developed virtually simultaneously as two sets of fractures inclined to the sedimentary layers. Lateral variations in the spacing of F3A and F3B 

joints are slight within the small area studied, but differences 

in spacing from bed to bed are pronounced and abrupt. The 

F3A and F3B joints are best developed in rich oil shales but 

are absent, or sparse, in lean oil shales, marlstones, and 

sandstones. Studies of joints in surface exposures thus are 

of uncertain value in predicting the spacing, or even the existence, of F3A and F3B joints in different rocks at depth.

The large, inclined surfaces of F3A and F3B joints may 

seriously weaken pillars, roofs, and some walls in 

underground mines. The collapse of excavated faces in 

mines, along roads, and in open cuts is possible wherever 

the F3 trend is nearly parallel to the cut face, and particularly where the joint set dipping toward the face is well 

developed or undercut.

JOINT SET F4

Joints of this set are among the most common in the Piceance basin. The F4 joints generally are small, and few cut 

more than one bed. They are second only to F2 joints in 

abundance and are developed throughout an equally large 

area. Like F2 joints, F4 joints generally are abundant in lean 

oil shales and become progressively more widely spaced in 

richer beds. The trend of the F4 joint set gradually changes 

orientation from nearly due north at Rio Blanco to northeast 

at the mouth of Piceance Creek; the F4 joints thus are nearly perpendicular to F2 joints in most places. The F4 joints 

probably facilitate movement of ground water through 

bedrock by providing permeable cross-linkages between adjacent F2 joints, presumably the main conduits for groundwater flow.

JOINT SET F5

The F5 joints are nearly parallel to F2 joints and hence are 

readily confused with them. However, F5 joints do not extend from one bed into another, are younger than F4 joints, 

and show little evidence of past ground-water flow (the surfaces of F5 joints are fresh and are not lined with calcite). 

The F5 joints are much less abundant and open than F2 

joints.

PATTERNS OF THE EIGHT JOINT SETS 

CAN BE SUMMARIZED

Eight sets of joints have been recognized to date within 

rocks of the Green River Formation in the Piceance basin. 

Only two of the eight sets occur throughout the formation, 

thus dominating the joint pattern in most parts of the basin. 

The joints of five other sets are only locally common, and 

the joints of one set are small and insignificant.

The two dominant sets trend generally west-northwest 

to northwest (F2 ) and north-northeast to northeast (F4 ), 

forming a nearly perpendicular network of joints on a 

regional scale. Shapes of joint-bounded blocks are determined by the relative abundance of members of each set, 

and range from northwest-trending vertical slabs (as 

shown in the photographs) where F4 joints are sparse, to 

vertical prisms where F4 joints are abundant. This simple 

fracture pattern locally is modified by joints of other sets, 

but only rarely are more than four sets present in the same 

outcrop.

The F2 and F4 joints probably dominate the fracture pattern of the buried oil shales of the basin interior as 

thoroughly as they do the exposed rocks along the basin rim. 

It is likely that the flow of ground water beneath the Piceance basin is influenced strongly by the distributions, sizes, 

spacings, openings, and interconnections of F2 and F4 

joints. Ground water within any particular bed thus will 

flow more readily in some directions than others that is, 

horizontal permeabilities are strongly direction dependent 

in fracture-controlled aquifers. The direction of greatest 

horizontal permeability within a bed will not necessarily be 

parallel to the joints of either set.
THE ORIENTATIONS AND SIZES OF THE JOINTS PORTRAYED ARE TYPICAL OF NATURAL 

EXPOSURES. MOST OUTCROPS CONTAIN ONLY TWO TO FOUR OF THE EIGHT KNOWN SETS. 

Joints of sets F1A and F1B are shown only in the upper bed of the upper block for clarity; in 

natural exposures they generally are associated with other sets. 

Joints of sets f1A, F1B , F2 , ^JA/ and F3B are "bed transgressive" in that they typically extend through 

several or more beds, especially where all beds are of similar rock type. Spacings of these joints 

in such areas may be highly variable, as shown. Where beds of different rock types of oil shales 

of markedly different richness occur together, however, joints of all sets tend to be bed confined 

and terminate against the upper and lower surfaces of individual beds. Resultant spacings of joints

are then proportional to bed thickness, with thicker beds containing more widely spaced joints. 

Joints of sets F4 and F5 tend to be bed confined regardless of contrast in rock type. The spacings 

of F4 and F5 joints increase with increasing bed thickness, as shown in the block diagram. 

Relative ages of the joint sets can be determined from this diagram, keeping in mind that younger 

joints terminate against older. In this respect joints differ markedly from most faults. Faults are 

fractures along which substantial slip generally has occurred, and faults thus tend to offset all 

preexisting fractures. Joints, however, are fractures along which slip has been negligible or nil. 

The small amount of movement along most joints is not sufficient to propagate the joints from 

one block of rock into another, across a preexisting joint. Instead, younger joints will terminate 

against older. If joints of an early set are filled by calcite or some other mineral, however, the 

joints are recemented and younger joints may cut across them. An X intersection two joints cross- 

ing each other is not diagnostic of age relationships. 
EXPLANATION

* Sedimentary bed 0 10 FEET

0123 METERS

Schematic block diagram of joint sets in the Green River Formation (fig. 32).

Cn
TABLE 3. Characteristics of Joint Sets in the Green River Formation

Orientation

Set Strke

Dip

Size of joints: L- length;

H = height (the distance along the

dip of the joint plane);

LxH = A- surface area Spacing 1 Termination

Engineering and hydrologic 

significance Remarks

ts)

F1A Generally NW to NNE. L: 5 to 20 ft; locally as much as

60ft. 

H: 1 to 6 ft typically, up to 15 ft

locally. 

A: Variable; 5 to 50 ft2, but up

to 200 ft2 or more locally.

Variable; 4 in. in some beds; 

3 to TO ft in others. 

Locally abundant in rich oil 

shales.

50°-70°NE.

Tops and bottoms of F ; joints 

commonly terminate against 

bedding planes. FW and F ?e 

are contemporaneous sets; some FjA terminate against Fjg, and some F ?B against

F 1B Similar to F 1A but with 

45°-50°SW dips.

Possible adverse effects on slope 

stabilities in surface 

excavations and on mine-roof 

stabilities in underground passages.

F^A and F Jg joints are locally 

important conduits for groundwater flow.

Offsets of bedding by V4 in. or 

less along F 1A and F ?g are 

common. F JA and F Jg joints 

are minor shear fractures analogous to small normal 

faults.

I :but

 tre

near

(as"

jb -5;to;-50 .ft; /.soOTe; Much: longeiy 

 H; '2 lo TO/.tejsbme.migich'/N^her. 

A:: .Variable;: coMTtmonfy 10 to 

30 .ft2 in thin-bedded rocks, 

but 1:QO.to 300 ft2 ormor? fh 

massive O!:l$.:Ha.le's:»

Vertical,

.Extremely yarfebfe,.: with abry pt 

lateral, changes. 1 jri-same 

wassive oii: shales; Spacings 

are commonly 6 to 20 ft in 

>ich"0if shales^ In. wejl-beclded 

 units,' $* Sp#emg.'.is. proportional 

to Sickness -of 'bed.

Termfhate; agairat F^- arid: f: f 

joints whe.r£'..th: ese are 

developed;; F^jof riti cut 

numerous bedding.::plaries

'.wbfcre rocfc type-is-'.relatively 

uniform; these ar6: (he largest 

'$2 joints.; Where, djjfefe.nt:roctc. 

types :arf;intf rbedded; 'Fg .{pints 

:afe: .Smaller and. terminate

stabtlMe'S: In '.surface' 

:excavati6i1s: .arid: on roof 

stabiJities Ifi uftdiergrburtd mine 

oassagpsj

Probably one.of the. .major sets. 

througrt .which;:gr<9un<f water

Open Fj.-joints *tre.~ocm>m(m'-at '

the surface and at.depth. 

One of the major joint sets:.of

.the.vPlce'ance basinl 

Fjj^jcrints are,,extens|.pn 'ff.ictu.res. ! 

and'.y^efpped after compaction 

«f: "the- jprlgiftaf "sediments?

N70°-80°EJ

55°-65°NW

L: Poorly known; 10 to 30 ft is 

common minimum; could be 

much more.

H: 6 to 20 ft.

A: Large; commonly hundreds of 

square feet.

V3B

N70°-80°EJ

Variable, and probably dependent 

in part on rock type. Spacings 

are 2 to 10 ft where well developed.

Terminate laterally against F2 

joints. F3A and F3B are 

contemporaneous sets; some F3A terminate against F3B, and 

some F3B against F3A.

55°-65°SE

Large, inclined, and commonly 

open fractures roof and wall stabilities in underground mines 

may be impaired, and strength 

of pillars may be significantly 

reduced.

F3A and F3B joints may reduce 

stability of some road cuts and 

benches in surface excavations.

Not commonly seen, but locally

abundant. 

May be present at depth even if

absent in surface exposures. 

Mechanics of development not

well known; probably shearfractures.

I

Generally NE to NNE, 

but curving to N-S 

trends locally (as near 

Rio Blanco)

L: Dependent on F2 spacing.

Lengths of 2 to 10 ft arecommon. 

H: Dependent on bed thickness;

commonly 0.5 to 1.5 ft.,

locally up to 10 ft. 

A: Small to moderate; commonly

2 to 30 ft2 .

Variable; 1 to 5 ft, locally much 

more, dependent on bed 

thickness and rock type. 

Thin beds and lean oil shales contain the most abundant 

F4 joints.

Terminate against all previously 

formed joint sets, and against 

prominent bedding planes.

Vertical.

Possible adverse effects on slope 

stabilities in surface 

excavations and on roof 

stabilities in underground mine 

passages.

Probably facilitates ground-water 

flow in the basin by providing 

permeable linkages between 

adjacent F2 fractures.

Where beds are thin and F2 

joints are widely spaced, F4 joints are long, ribbon-like 

fractures. Their lengths decrease as F2 spacings decrease.

One of the major joint sets of 

the Piceance basin.

F4 joints are extension fractures.

Generally WNW to NW, 

but curving to E-W 

trends locally (as near 

Rio Blanco).

Vertical.

L: Dependent on F4 spacing;

commonly 1 to 5 ft. 

H: Dependent on bed thickness;

commonly 0.5 to 1.5 ft. 

A: Small; commonly 1 to 10 ft .

Variable; 0.5 to 3 ft where well Terminate againt all other 

developed. Thin beds and lean systematic joint sets and oil shales contain the most abundant joints. Where F2 joints are closely spaced, F5 

joints tend to be rare or absent.

Little, if any.

against prominent bedding 

planes.

Parallel to F2 joints, and 

distinguished from them by 

their smaller size, their 

tendency to terminate against 

all prominent bedding planes, 

and their late age relative to 

joints of all other sets.

F5 joints are late extension 

fractures.

Values given indicate commonly observed ranges rather than observed extremes. Some F4 joints, for example, have L-0.8 to 1.2 in., H-0.08 to 0.15 in., A-0.06 to 0.20 in. 2 , and are spaced 0.2 to 0.8 in. apart.

2Features described here are mostly those used as diagnostic evidence of relative age. Some joints ceased growing before the advancing fracture encountered a joint of another set or a bedding plane. Other joints propagated across previously 

formed recemented fractures rather than terminating against them. Where two joints cross in an X, it is commonly difficult to determine which is the younger fracture. Many members of each joint set must be inspected to ensure reliable determinations of relative age of sets.

Regional distribution of this set is poorly known. Orientations in some areas not yet examined may differ significantly from those quoted here.
SYSTEMATIC JOINTS OF THE GREEN RIVER FORMATION 53

JOINT SPACING DEPENDS UPON BED 

THICKNESS, ROCK TYPE, AND 

DEPTH BELOW LAND SURFACE

Bed thickness, rock type, and depth below the surface 

significantly affect the spacing of joints within rocks of the 

Green River Formation.

BED THICKNESS

For any given rock type, the spacing of joints in different 

beds of the same outcrop generally can be shown to be proportional to bed thickness thicker beds contain more widely spaced joints. Measurements of average joint spacing 

within selected beds of different thickness commonly are 

portrayed on a graph, from which spacings of joints in all 

other beds of the same rock type can be predicted. Several 

such graphs, one for each rock type, can then be used to 

predict spacings of joints in unexposed rocks in advance of 

mining, if bed thickness and rock type are first determined 

from a drill core, which is a routine exercise. Complications 

that restrict the effectiveness of this simple procedure include 

changes in the relation between spacing and thickness that 

occur from set to set, from one locality to another, and with 

depth. Additional spacing measurements, for each joint set 

and at multiple localities, will remove or compensate for 

most such difficulties.

ROCK TYPE

Some effects of rock type on joint spacing already have 

been mentioned. For example, both F2 and F4 joints become 

progressively more widely spaced with increasing richness 

of oil shale. The dependence of joint spacing on rock type 

can be measured directly, and most accurately, only where 

different rock types occur together in beds of equal or similar 

thickness. In most places, however, the effect of variations 

in joint spacing due to differences in bed thickness must be 

calculated before spacings among different rock types can 

be compared.

DEPTH BELOW LAND SURFACE

Once the dependence of joint spacing on bed thickness 

and rock type is known, it should be possible to define the 

relationship between joint spacing and depth below the surface. Little is yet known, however, about the effect of depth 

on joint spacing in the Piceance basin, except that rocks at 

increasing depths generally contain fewer and more tightly 

closed joints. Measurements within one oil-shale mine revealed a 250-percent increase in joint spacing within a vertical interval of 500 feet, but the rate at which joint spacings 

increase with depth is likely to vary from one part of the 

basin to another.

Based on the above criteria, the fewest joints should be 

found in the most thickly bedded and richest oil shales at 

depth for example, in the Mahogany zone. Even at the surface, where these same rocks are exposed as the Mahogany 

ledge, it is apparent that the massive and rich oil shales 

generally contain far fewer joints than any other rock unit. 

The paucity of joints in these rocks is reflected in their 

tendency to retard vertical mixing of ground water circulating above and below them, and it has led to the conventional recognition of an upper and lower series of 

bedrock aquifers separated by the less permeable Mahogany 

zone, all of which are discussed in the chapter "Hydrologic 

system of the Piceance basin." As with any other generality, however, exceptions to this simple subdivision are expected and found. In some parts of the basin, as along 

segments of Cathedral Bluffs on the western side of the basin, 

joints within the Mahogany zone are both large and abundant. Here the Mahogany zone may transmit water readily, and a distinct series of upper and lower bedrock aquifers 

probably does not exist.

o.oi

0.0050.01 0.050.1 05 1 

BED THICKNESS, IN FEET

10

Relation between spacing of F2 joints and bed thickness for 

fine-grained sandstones and siltstones of the Green River Formation near Rio Blanco (fig. 33).
Cn

f^fe ^^^a&sfc? - -Jib

Closely spaced joints in an upper lean zone about six feet thick, and widely spaced joints in a lower rich zone of the Mahogany ledge near the junction of Piceance

Creek and the White River (fig. 34).
SYSTEMATIC JOINTS OF THE GREEN RIVER FORMATION 55

REFERENCES

Grout, M. A., and Verbeek, E. R., 1983, Field studies of jointsinsufficiencies and solutions, with examples from the Piceance Creek 

basin, Colorado, in Gary, J. H., ed., Proceedings, 16th Oil Shale Symposium: Colorado School of Mines Press, Golden, Colorado, p. 68-80.

Kelley, V. C, and Clinton, N. J., 1960, Fracture systems and tectonic 

elements of the Colorado Plateau: University of New Mexico Publications in Geology, no. 6, 104 p.

Smith, R. S., 1980, A regional study of joints in the northern Piceance basin, 

northwest Colorado: Golden, Colorado School of Mines M.S. thesis, 

126 p.

Smith, R. S., and Whitney, J. W., 1979, Map of joint sets and airphoto 

lineaments of the Piceance Creek basin, northwestern Colorado: U.S. 

Geological Survey Miscellaneous Field Studies Map MF-1128, scale 

1:100,000.

Verbeek, E. R., and Grout, M. A., 1983, Fracture history of the northern 

Piceance Creek basin, northwestern Colorado, in Gary, J. H. (ed.), Proceedings, 16th Oil Shale Symposium: Colorado School of Mines Press, 

Golden, Colorado, p. 26-44.

Verbeek, E. R., and Grout, M. A., 1984, Fracture Studies in Cretaceous 

and Paleocene strata in and around the Piceance basin, Colorado 

Preliminary results and their bearing on a fracture-controlled natural 

gas reservoir at the MWX site: U.S. Geological Survey Open-File Report 

84-156, 30 p.

Verbeek, E. R., and Grout, M. A., 1984, Prediction of subsurface fracture 

patterns from surface studies of joints An example from the Piceance 

Creek basin, Colorado, in Spencer, C. W., and Keighin, C. W., (eds.), 

Geologic studies in support of the U.S. Department of Energy's Multiwell 

Experiment, Garfield County, Colorado: U.S. Geological Survey OpenFile Report 84-757, p. 76-86.

Grout, M. A., and Verbeek, E. R., 1985, Fracture history of the Plateau 

Creek and adjacent Colorado River valleys, southern Piceance basin 

Implications for predicting joint patterns at depth: U.S. Geological Survey 

Open-File Report 85-744, 17 p.

Unconsolidated sedimentary deposits overlie the bedrock 

framework of the Piceance basin. Some of these deposits 

are associated with the stream system. A discussion of 

alluvial and fan deposits of unconsolidated material follows.

UNCONSOLI DATED DEPOSITS OF THE PICEANCE BASIN

By FRANK A. WELDER

A variety of alluvial deposits has been emplaced in the 

Piceance basin during the last 10,000 years. Most of these 

deposits lie in stream valleys between the stream channel 

and the bedrock. The alluvial deposits affect the characteristics of the stream and the interchange of water between 

the stream and the bedrock aquifers. Permeable and 

saturated alluvial deposits are valley-fill alluvial aquifers 

from which a water supply can be obtained. An understanding of the alluvial deposits is needed in order to assess their 

effects on the hydrologic system in the basin under natural 

conditions and under conditions of mineral development, 

including mine drainage.

ALLUVIAL AND FAN DEPOSITS 

FILL THE STREAM VALLEYS

The valleys of the Colorado and the White Rivers and 

their tributaries are partly filled with alluvial deposits and 

fan deposits. These sediments were deposited by water in 

the Holocene Epoch of the Quaternary Period (see table 1). 

East of Meeker, the alluvium in the White River valley is 

more than 100 feet thick and supplies ground water through 

wells to the city. Exploratory drill holes also have penetrated 

varied thicknesses of saturated alluvium in the valleys of 

Roan, Parachute, Piceance, and Yellow Creeks.

Test holes in alluvium of Roan Creek about 5 miles 

upstream from De Deque (section A-A ') penetrated about 

80 feet of saturated permeable sand and gravel. On 

Parachute Creek about 3 miles upstream from Parachute 

(section B-B'), test holes penetrated about 70 feet of 

saturated permeable sand and gravel.

In the alluvium of Piceance Creek, test holes drilled 

upstream from the confluence of Willow Creek (section 

C-C') penetrated about 70 feet of saturated permeable sand 

and gravel. However, about 8 miles further downstream at 

the junction of Piceance Creek and Ryan Gulch (section 

D-D'), test holes drilled in Piceance Creek valley penetrated 

dark gray to blue, dense organic clay as much as 70 feet 

thick, extending across most of the valley. At the junction 

between the two stream valleys, a spring flows at a rate of 

about 150 gallons per minute. The water emerges from the

valley floor at the contact with the bedrock that forms the 

valley wall.

Westward in Yellow Creek valley (section E-E'), test holes 

penetrated 35 to 45 feet of saturated sand and gravel. About 

5 miles downstream from this location and immediately 

upstream from the junction with Barcus Gulch (section 

F-F'), test holes drilled in Yellow Creek valley penetrated 

as much as 80 feet of dark gray to blue, dense organic clay.

Alluvium is composed of materials that have been transported by turbulent water currents and deposited when the 

current velocity decreased. Alluvial deposits are typical in 

most river valleys. They are found at some sites in the 

valleys of Roan, Parachute, Piceance, and Yellow Creeks. 

In contrast, the thick, dark-colored, organic clay found at 

the two sites along Piceance and Yellow Creeks is commonly 

deposited in a lake environment. The extreme difference between stream and lake environments in Piceance and Yellow 

Creek valleys poses two major questions:

1. How were the clay beds formed in a river valley?

2. What is the effect of the clay beds on ground-water 

movement in the valley-fill material?

NATURAL DAMS PROBABLY FORMED LAKES 

ALONG PICEANCE AND YELLOW CREEKS

During early Holocene time, the flood plains of Piceance 

and Yellow Creeks probably were at least 60 feet lower than 

at present. A change in weather pattern may have concentrated and intensified rainfall in the catchment areas of some 

large tributaries. The resulting increased streamflow carried 

large quantities of sand and gravel down to the flood plain 

of the main stream valley, where the sediment was deposited 

as a large fan at the mouth of each tributary. Progressively 

the fan extended across the main stream valley, and ultimately the fan deposits became a dam, impounding 

streamflow and creating a lake, which may have extended 

more than a mile upstream. The coarse sediment sand and 

gravel was deposited where the main stream entered the 

lake. The fine sediment silt and clay was carried into the 

lake where it slowly accumulated to form a large clay plug 

that thins upstream from the dam.

57
58 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

R1GOW _ 1GB°30' _____P98W

 ~-«L> ^

V ^-f

\ ^ _ ^r ,oK /

: V. ^__ . ...

_ GARJF1ELDCO ~ 

MESA CO

L*"~?2

15 MILES

J

0 5 10 15 KILOMETERS 

Locations of cross sections where the valley-fill alluvium was explored by drilling (fig. 35).
I: ' _! ' H'-iL'- S' -'.i?7 ±!L'-'-'-'»!£: - ^.-^oly

5100

5000

B

FEET 

5500 -i

5400 - 5300

5200

FEET FEET 

5300 6400-1

Section A-/A' shows about BO feet of saturated permeable sand 

and gravel along Roan Creek, 5 miles upstream from DeBeque

"O '." m^/p ,*t o £ p ! ® 'Q ° <~*~io~' &T~t0 ,**»^. '*» /.. '/" "* .* " " '"^ *~o'""-"* '"i"7 .' f\

Bedrock

Section B-B' shows about 70 feet of saturated permeable sand and 

gravel along Parachute Creek, 3 miles upstream from Parachute

5200 6300-

-5100 6200

5000 6100

-5400

-5300

-5200

6100

Section C-C" shows about 70 feet of saturated 

permeable sand and gravel along Piceance Creek near Willow Creek

EXPLANATION

POTENTIOMETRIC SURFACE

CONTACT BETWEEN ALLUVIUM 

AND BEDROCK

SAND AND GRAVEL

CLAY, SAND, AND GRAVELSAND AND CLAY

TEST HOLE

500

_l_

1000 FEET

VERTICAL EXAGGERATION X 5.3

Alluvial deposits along stream valleys: Cross sections indicate permeable sand and gravel (fig. 36).

Ol
60

D

OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

F

FEET

6200-1

6100-

6000

5900

D'

FEET

r 6200

Bedrock

FEET 

5900 -i

6100 5800

-6000 5700-

5900 5600

F'

FEET 

r 5900

-5800

Alluvium

Bedrock

- 5700

5600

Section D-D' shows about 70 feet of clay within sand and gravel 

along Piceance Creek at Ryan Gulch

FEET 

6100

6000

5900-

5800

E'

FEET 

1-6100

-6000

Bedrock

Section F-F' shows about 80 feet 

of clay within sand and gravel along 

Yellow Creek near Barcus Gulch

EXPLANATION

 POTENTIOMETRIC SURFACE

-5900

CONTACT BETWEEN ALLUVIUM 

AND BEDROCK

SAND AND GRAVEL

CLAY, SAND, AND GRAVEL

SAND AND CLAY

TEST HOLE

5800

500 1000 FEET

Section E-E' shows about 40 feet of saturated sand and 

gravel along lower Yellow Creek

VERTICAL EXAGGERATION X 5 3

Lake and alluvial deposits along stream valleys: Sections D-D' and F-F' indicate tight clay lake deposits associated with permeable 

sand and gravel alluvial deposits. Clay was not detected in section E-E' (fig. 37).

GROUND WATER AND SURFACE WATER 

ARE INTERRELATED

The stream-deposited sand and gravel and lake-deposited 

clay have different permeabilities that affect water movement through the valley-fill alluvial aquifer and also affect 

streamflow. Water in the aquifer moves in the downstream 

direction. Where the aquifer consists of permeable sand and 

gravel, the water movement is relatively rapid, and the water 

table may be 10 feet or more below the land surface. In these 

valley reaches, the water in the alluvium does not discharge

to the streams, which thus go dry during periods of low 

precipitation. Where the water moving down the valley encounters the relatively impermeable clay of a former lake, 

the rate of water movement in the aquifer is reduced, and 

most of the water moves upward toward the land surface 

between the clay plug and the bedrock. The water forced 

upward discharges as springs, which maintain streamflow 

throughout the year. The type of material in the alluvial 

deposits determines whether the water moves downstream 

as ground water in the alluvium or as surface water in the 

stream channel.
UNCONSOLIDATED DEPOSITS 61

D

Lake formation in Piceance basin. A, Initially a stream and tributary flowed over valleyfill alluvium. B, Increased flow in the tributary 

transported large quantities of sediment into the main stream valley. This sediment was deposited as an alluvial fan at the mouth 

of the tributary. C, As the alluvial fan enlarged, it displaced the stream in the main valley. D, Eventually the fan dammed the stream, 

caused the formation of a lake, and allowed fine sediment to accumulate in the lake (fig. 38).

The bedrock aquifers of the Uinta and Green River Formations discharge in the valleys of Piceance and Yellow 

Creeks. Some investigators believe that most of the springs 

in the Piceance basin are supplied directly by water discharging from the bedrock aquifers through fractures. If this is 

so, drainage of the bedrock in the process of mining oil shale 

would dry up the springs and rapidly decrease streamflow. 

However, based on geologic studies of the extensive clay 

deposits in some reaches of the valleys of Piceance and 

Yellow Creeks, the connection between the bedrock aquifers 

and the valley-fill alluvial aquifers is limited. Therefore, in 

some regions of the basin, the drainage of mines in the 

bedrock will affect the streamflow and water in the alluvium 

less rapidly, because the clay will retard the movement of 

the water. The hydrology of the bedrock aquifers is discussed in greater detail in the following chapter "Hydrologic 

system of Piceance basin."

REFERENCES

Bass, N. W., and Northrop, S. A., 1963, Geology of Glenwood Springs 

quadrangle and vicinity, northwestern Colorado: U.S. Geological Survey 

Bulletin 1142-J, 74 p.

Coffin, D. L, Welder, F. A., Glanzman, R. K., and Dutton, X. W., 1968, 

Geohydrologic data from Piceance Creek basin between the White and 

Colorado Rivers, northwestern Colorado: U.S. Geological Survey Circular 12, 38 p.

Lohman, S. W., 1965, Geology and artesian water supply. Grand Junction 

area, Colorado: U.S. Geological Survey Professional Paper 451, 149 p.

The streams and ground water in the Piceance basin are 

part of the Colorado River basin in which water shortages 

are common. Mineral development will disrupt the local flow 

systems and consume part of the available water supplies. 

A description of the characteristics of the flow system and 

Colorado water law follows.
SJ

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Aerial view showing the displacement of Piceance Creek toward a county road by an alluvial fan at the mouth of a tributary valley (fig. 39).
HYDROLOGIC SYSTEM OF PICEANCE BASIN

By O. JAMES TAYLOR

Oil-shale development cannot proceed in many parts of 

the Piceance basin without mine drainage. It also will require water supplies for various industrial activities, which 

are discussed in the chapter "Development of the oil shale 

and associated minerals." Furthermore, the changes in the 

flow systems in the Piceance basin will affect water supplies 

in other parts of the Colorado River basin. Therefore, an 

understanding of the hydrologic system in the Piceance basin 

is important.

THE PICEANCE BASIN IS PART 

OF THE COLORADO RIVER BASIN

The Colorado River basin is divided into an upper and 

a lower basin in order to allocate water supplies, as specified 

in the Colorado River Compact of 1922. The Piceance basin 

lies near the center of the Upper Colorado River Basin, a 

drainage basin of about 113,500 square miles, which includes 

parts of Arizona, Colorado, New Mexico, Utah, and 

Wyoming.

This upper basin has an arid to semiarid climate with a 

normal annual precipitation of only about 16 inches. Precipitation, in the form of rainfall and snow, is the source 

of the water that replenishes streamflow and recharges the 

ground-water reservoirs. Evapotranspiration consumes a 

large part of the precipitation before it can contribute to 

surface- and ground-water supplies. Therefore, the relatively 

small average precipitation results in small water supplies, 

especially in relation to the large water demands in the Colorado River basin, and therefore water shortages are 

common.

The large and diverse water demands in the upper basin 

will probably continue to increase. During 1982, the most 

water was used for irrigation; other uses included export 

to other basins, powerplant cooling, mineral development, 

municipal supply, other industrial use, support of fish and 

wildlife, and recreation. Increased demands are expected for 

all of these uses, as well as for development of oil shale, 

tar sand, and coal. Available water will not be sufficient 

for major oil-shale development during years of average 

precipitation unless supplies are increased, storage facilities 

are constructed, and use of water for other purposes is 

decreased or eliminated.

PRECIPITATION REPLENISHES THE STREAMS

Normal annual precipitation in the Piceance basin ranges 

from about 12 to 20 inches. In general, the larger volumes 

fall at higher altitudes, where more than one-half of the 

precipitation accumulates as snow. The snowpack normally persists through the winter until the spring thaw. At lower 

altitudes, the precipitation is approximately one-half rainfall and one-half snowfall, and the snowpack usually melts 

during the winter. The air temperature at the lower altitudes 

is warmer than that at the higher altitudes.

Most precipitation is lost to evapotranspiration; an 

estimated 98 percent of the snowmelt and precipitation is 

evapotranspired. The remaining water runs off rapidly and 

replenishes streamflow or recharges the aquifers. The natural 

recharge replenishes the ground water that moves slowly 

toward sites of natural discharge along the streams. During 

periods of intense rainfall or snowmelt, most of the 

streamflow is derived from surface runoff. During dry 

periods, most of the streamflow is derived from ground 

water discharging into the streams.

The Piceance basin includes four major drainage basins. 

Piceance and Yellow Creeks drain the northern part of the 

Piceance basin and discharge into the White River. Roan 

and Parachute Creeks drain the southern part of the Piceance 

basin and discharge into the Colorado River.

Hydrologists measure streamflow periodically or continuously at selected monitoring sites. Measurements taken 

over a period of many years are used to calculate statistics 

that describe the low-flow, mean-flow, and flood-flow 

characteristics at each site. The mean annual discharge at 

the mouth of each creek is tabulated below; the total indicates the volume of annual flow.

Mean annual discharge in acre-feet 

Piceance Creek .......................................... 17,320

Yellow Creek ........................................... 1,240

Roan Creek ............................................. 32,140

Parachute Creek ......................................... 21,810

Total ................................................ 72,510

The different mean annual discharges for the four drainage 

basins are due to the different amounts of mean annual 

precipitation, snowpack thickness, type and amount of 

vegetation cover, and drainage area for each basin.

63
64 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

110°

&-..

/I The Upper Colorado River Basin

C encompasses an area of about

* 113,500 square miles

107°

Major deposits of oil 41° 

shale, tar sand, and 

coal are found in this f 

region

W~ .TA

The Piceance basin 

encompasses an area 

of about 1600 square 

miles

~n r

50 100 KILOMETERS

Changes in the water resources of the Upper Colorado River Basin 

also may affect the lower basin States of Arizona, California, 

Nevada, New Mexico, and Utah; Mexico; and regions that export 

water from the upper basin

The Upper Colorado River Basin (fig. 40).
HYDROLOGIC SYSTEM 65

RIOOW 10B°3D' P96W R57';V 196W R95W 1DB°00

RIO BLANCOiCO 

At lower altitudes about

\, one-half of the precipitation 

is rainfall and one-half is 

nowfall

\

LINE OF EQUAL NORMAL 

ANNUAL PRECIPITATION, 

IN INCHES

Normal annual precipitation 

ranges from 12 to 20 inches 

Larger volumes of precipitation commonly fall 

higher altitudes

t higher altitudes more thanN/ 

ne-half of the precipitation__ i

snowfall. The snow GARHELD CO 

ommonly accumulates in a ^. i

RIO BLANCO CO

nowpack that persists 

Trough the winter until 

the spring thaw

Anvil Points 

Rulison

I 

15 KILOMETERS

15 MILES

I

Normal annual precipitation in Piceance basin 1931-60 (fig. 41).
66 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

P100W R93W

RIO BLANCOiCO

'Surface water in 

the northern 

part of Piceance 

basin drains into 

\J__ the White River, j 

i a tributary of the 

Green River that

/ drains into the / 

Colorado River Meeker

- DRAINAGE BASIN

PICEANCE CREEK 

DRAINAGE BASIN

L / ' /! 

RIO BLANCO CO

PARACHUTE CREEK 

DRAINAGE BASIN

ROAN CREEK 

DRAINAGE BASIN

Surface water if?

15 MILES

15 KILOMETERS

Major drainage basins of the Piceance basin (fig. 42).
DISCHARGE, IN CUBIC FEET PER SECOND

M > d> 000

DISCHARGE, IN CUBIC FEET PER SECOND 

ooo

n wD3 

oQ. t/in3- cu

OQ

-fc>U>

OCT

NOV

DEC

JAN

FEB

MAR

APR

MAY

JUNE

JULY

AUG

SEPT

OCT

NOV

DECJAN

FEB

MAR

APR

MAY

JUNE

JULY

AUG

SEPT

1

1

1

1

a 

o

||

*3 1

T3 33

0

m

n

33m

7v55n

m

a

8

n 

%en

32 S 

o S

m >

O

mn
68 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

The tabulated values of mean annual discharge of the 

creeks do not indicate the large annual and seasonal variations in flow. Peak stream discharges usually occur during 

the spring following snowmelt and during the summer 

following intense rainfall. Low-flow conditions are common 

during late fall and winter, when streamflow is mostly supplied by discharge from the ground-water reservoirs to the 

stream valleys. Irrigation practices along the flood plains also 

affect the magnitude of streamflow.

Stream water moves faster at high-flow than at low-flow 

conditions. During peak flows, water probably moves from 

the headwaters to the mouth of Piceance Creek in about a 

day; during low flows, however, the travel time can be several 

days. Ground water moves much more slowly than surface 

water.

A WATERSHED MODEL IS USED TO STUDY 

THE SURFACE-WATER SYSTEM

Water-resource systems are so complex that an accurate 

understanding of their behavior requires numerous field 

measurements that can be used in the solution of many complex equations. The required calculations are so tedious that 

models are often prepared. The surface-water system in parts 

of the Piceance basin has been studied using a watershed 

model. This model simulates the principal components of 

the surface-water system including precipitation, snowmelt, 

sublimation, evapotranspiration, overland flow, infiltration, 

and natural recharge. In order to use the watershed model, 

the hydrologist subdivides a map of a watershed into 

hydrologic-response units areas that are considered 

homogeneous with respect to the land slope, the compass

direction that the slope faces, the type of vegetation, the type 

of soil, and the distribution of the snowpack.

The model is operated by coupling data describing the 

physical and hydrologic characteristics of each hydrologicresponse unit with the appropriate physical and hydrologic 

flow equations which are solved using a computer. The 

watershed model also calculates the cumulative hydrologic 

effects of each hydrologic-response unit, in order to predict 

the total streamflow from the watershed.

The watershed model needs to be calibrated to insure 

reasonable accuracy. Model calibration is effected by adjusting the data describing the physical and hydrologic 

parameters and possibly the flow equations until simulated 

streamflow approximates actual streamflow. A model is said 

to be calibrated if it accurately simulates the observed streamflow. However, the model may fail to simulate streamflow 

under extreme conditions that were not used in model calibration, and then the calibration process must be repeated.

CALIBRATED WATERSHED MODELS 

HAVE BEEN USED TO STUDY 

THE SURFACE-WATER SYSTEM 

OF THE PICEANCE BASIN

Watershed models prepared for the northern part of the 

Piceance basin have improved the understanding of the 

surface-water system of the basin. Simulation of the natural 

flow system indicates that natural recharge to bedrock 

aquifers is greatest in areas of high land-surface altitude, 

presumably because the thick snowpack and the slow 

melting process allow infiltration.

Hydrologic flow components simulated in watershed model (fig. 44).
HYDROLOGIC SYSTEM 69

Map of drainage basin subdivided into hydrologic response units 

for watershed modeling (fig. 45).

Simulation of the surface-water system for various levels 

of hypothetical oil-shale development indicates that the 

development of a large oil-shale industry may increase surface runoff. Spoil piles emplaced in areas of natural recharge 

may reduce or eliminate recharge. A reduction in natural 

recharge may correspondingly increase surface runoff.

Watershed models cannot answer all questions or solve 

all problems related to surface-water hydrology. They are 

simplified representations of complex systems. They can help 

us to understand which factors have the most effect on the 

system and possibly to predict the hydrologic effects of 

various courses of action, land-use decisions, and levels of 

development.

THE GEOLOGIC FORMATIONS 

ASSOCIATED WITH OIL SHALE INCLUDE 

GROUND-WATER RESERVOIRS

Geologic formations are an important part of the hydrologic system of Piceance basin because all or parts of some 

of them are aquifers. The aquifers transmit and store water 

and form a major part of the overall flow system. The

aquifers associated with the oil shale in the basin are several 

permeable zones within the Green River Formation and the 

Uinta Formation. The zones are permeable because they have 

fractures and interconnected pores. Geologic beds that are 

less permeable than the aquifer zones tend to retard groundwater movement, but do not stop it. Fractures are discussed 

in detail in the chapter "Systematic joints within oil shales 

and associated rocks of the Green River Formation."

The Garden Gulch Member of the Green River Formation is comprised of marlstone and sandstone that are not 

permeable. This member and stratigraphically equivalent 

beds in the southern part of the basin form a lower boundary for the overlying aquifers that are associated with the 

oil shale.

The aquifer zones within the lower Parachute Creek 

Member of the Green River Formation overlie the Garden 

Gulch Member. These aquifers were formed when the brittle oil shale was fractured and part of the soluble minerals 

were dissolved by circulating ground water. Locally, these 

aquifers are called the lower aquifers. In the northern part 

of the Piceance basin, an unfractured zone called the HR 

(high resistivity) zone lies just above the Garden Gulch 

Member. This zone was named for its high electrical 

resistance, as determined using geophysical logs. The HR 

zone is not permeable and, therefore, forms a boundary 

beneath the lower aquifers that stratigraphically overlie the 

Garden Gulch Member. Above the HR zone in the northern 

part of the basin is the leached zone. The solution of the 

minerals nahcolite, dawsonite, and halite formed many channels and resulted in a permeable zone within the upper part 

of the lower aquifers. The lower aquifers average about 900 

feet in thickness.

A confining layer known as the Mahogany zone of the 

Parachute Creek Member of the Green River Formation lies 

above the lower aquifer. This zone consists of rich oil shale 

with few fractures. The Mahogany zone confines the aquifers 

below it because its low permeability retards but does not 

stop water movement. The average thickness of the 

Mahogany zone is about 160 feet.

Stratigraphically above the Mahogany zone is a series of 

bedrock aquifers within the upper part of the Parachute 

Creek Member of the Green River Formation and the Uinta 

Formation. These aquifers consist of permeable sandstone 

and fractured siltstone of the Uinta Formation and fractured 

marlstone and solution cavities in the Green River Formation. Locally these aquifers are known as the upper aquifers. 

Their average thickness is about 700 feet.

The geology of the formations of Tertiary age that include 

these aquifers is discussed in the chapter "General geology 

of the Piceance basin."

Permeability of the upper and lower aquifers resulted from 

the structural deformation of geologic formations and the 

solution of minerals. Originally the formations consisted of 

fine, cemented particles of sedimentary rock. The sandstones
70 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

rf\ f?~-

^

r

/* % <*~>o "7>

^^

WEST

Recharged water moves through 

the upper and lower bedrock 

aquifers and discharges to the 

stream valleys

&* ^

->

^ 

'-VSV

vo,,

EAST

Valley-fill 

alluvium

Creek Member of Green

Lower part of Parachute Creek Member 

of Green River Formation

Garden Gulch Member of Green River Formation 

and older rocks

Not to scale

A. PICEANCE AND YELLOW CREEK DRAINAGE BASINS

WEST EAST

Recharged water moves through 

the upper and lower bedrock 

aquifers and discharges to 

springs above the Mahogany 

zone and possibly below the 

Mahogany zone

'" ^-^t?o^3 

^ GreetV

>tVcn

Lower aquifers

Lower part of Parachute Creek Member 

of Green River Formation

Garden Gulch Member of Green River Formation 

and older rocks

Not to scale

B. ROAN AND PARACHUTE CREEK DRAINAGE BASINS

Diagrammatic east-west sections of hydrologic system (fig. 46).
HYDROLOGIC SYSTEM 71

and siltstones were permeable because of their interconnected pores; the shales were not sufficiently permeable to 

be aquifers. However, fracturing of parts of the formations 

formed pathways that permitted water from snowmelt and 

rainfall to recharge the formation, and to dissolve and 

remove some of the minerals. These fractures and solution 

channels increased the permeability sufficiently so that many 

parts of the formations are now aquifers. Locally, the flow 

system is controlled by the fractures and solution channels; 

regionally, it is controlled by the precipitation pattern and 

the stream system.

PRECIPITATION RECHARGES THE AQUIFERS 

THAT STORE WATER AND TRANSMIT WATER 

TO STREAMS OR SPRINGS

A ground-water system is a dynamic system that stores 

and transmits water. The system is maintained by precipitation that infiltrates the ground and recharges the aquifers. 

Several ground-water models constructed for the Piceance 

basin indicate that natural recharge is about 36,000 acre-feet

per year. The ground water moves slowly toward regions 

of natural discharge, where it emerges from the aquifers.

The flow path taken by the ground water depends on the 

energy level throughout the flow system. This energy level 

is related to the altitude and pressure of the water at each 

point in the flow system. As the ground water moves, energy 

is consumed because of frictional losses as the fluid is forced 

through the fractures and pores in the rocks. Therefore, the 

ground-water movement is from higher to lower energy 

levels, which may be in any direction and not necessarily 

downward.

In the Piceance basin, the principal natural recharge is 

snowmelt that infiltrates the bedrock aquifers in the higher 

parts of the basin. The recharge moves slowly laterally and 

downward through the upper aquifers. The water in the upper aquifers follows the pathways created by the fracture 

system and the interconnected pores. In general, the water 

moves about twice as easily horizontally as vertically 

because the fracture-to-fracture connection is greater 

horizontally than vertically. Also the horizontal orientation 

of grains in the porous sandstone and siltstone promotes 

horizontal movement.

r ".^v^

C £&-^ j* r i i j *- » -

NORTH SOUTH

Natural recharge

Discharge 

to springs

Gveerx

BWet l6V^e'

,rr>toel

X_0\N eT

aQU'

_-^~i"">j * \ji« r^fccr^ 

Oppe^«erS ..-^c^-*^-- ^"blP-^Sfon^

 ^ra"Pa«cbUte ^o^ eT P^ Gree^ ^ ^ 

ahogarwj°?eot - itfers rfU 

Garden Gulch Member of Green River Formation 

and older rocks

Not to scale

Diagrammatic north-south section of hydrologic system (fig. 47).
72 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Part of the water moving downward through the upper 

aquifers eventually reaches the Mahogany zone. This zone 

is less permeable than the overlying and underlying aquifers 

because it generally lacks fractures. Although vertical water 

movement may be negligible through a small area of the 

Mahogany zone, it may transmit substantial quantities of 

water over its large areal extent.

Water passing through the Mahogany zone eventually 

enters the lower aquifers where it moves through fractures 

and the solution openings. Studies of the lower aquifers indicate that their horizontal permeability is as much as 15 

times greater than their vertical permeability because of the 

patterns of fractures and solution openings. Therefore, water 

can move more easily horizontally than vertically.

The water in the upper and lower aquifers moves horizontally through the basin to the discharge areas. In the Piceance 

and Yellow Creeks drainage basin, the water eventually 

moves upward through the aquifer system where it 

discharges into the valley-fill alluvial aquifer or emerges as 

springs in the stream valleys. In these valleys the water 

discharging from the bedrock mixes with water in the valleyfill alluvium and with water in the stream channel that 

originated as surface runoff. Measurements of streamflow 

along Piceance Creek indicate that:

1. Ground water discharging into the stream causes 

stream gains along many reaches, and

2. Surface water recharging the ground-water reservoirs 

causes stream losses along other reaches.

The stream gains exceed stream losses, with a net gain 

of about 15 cubic feet per second for the Piceance Creek on 

March 26, 1981. The indicated gains and losses will be 

understood more clearly when the measurements have been 

repeated at different times of the year, and the persistence 

of the gains and losses is determined.

In the Roan and Parachute Creek drainage basins, water 

moves horizontally through the aquifers to springs that 

discharge hundreds of feet above the streams in the deep 

canyons. Some of the discharged water evaporates, some 

is used by plants, and the rest flows down the steep bedrock 

slopes to the streams below.

Ground water moves very slowly in comparison to surface water. The maximum transit time for water movement 

from the recharge areas through the aquifer system to areas 

of discharge is probably many hundreds of years.

The total volume of ground water stored in the Piceance 

basin is not known, because the average porosity of fractures, pores, and solution cavities is not completely understood. The total volume of the upper and lower aquifers is 

approximately 480 cubic miles, and estimates of the stored 

ground water can be expressed in terms of estimated average 

porosities that range from 0.5 to 5 percent. The following 

table shows the volume of ground water stored in the Piceance basin corresponding to estimated average porosity 

of fractures, pores, and solution cavities.

Estimated average

porosity of

fractures, pores,

and solution

cavities

(percent)

Volume of 

ground water

stored in

Piceance basin

(millions of

acre-feet)

0.5

1

2

3

4

5

8

16

33

49

65

81

GROUND-WATER MODELS ARE USED 

TO STUDY THE FLOW SYSTEM OF THE 

AQUIFERS AND THE CONFINING LAYER

The subsurface flow system of Piceance basin has been 

studied using ground-water models because of the complexity of the flow system. These models are capable of 

simulating the integrated effects of recharge, movement, and 

discharge of water, as well as changes in stored water. Several 

models have been developed for parts of the Piceance basin. 

One current model, developed by the U.S. Geological Survey, 

simulates the aquifers, confining layer, major streams, and 

springs in the entire basin.

To use the ground-water model, the hydrologist subdivides 

maps of the flow system into layers and nodes. Data describing the aquifer characteristics within each node can be 

specified to account for different characteristics in various 

parts of the basin. The characteristics of permeability and 

storage due to the directional fractures and solution cavities 

are described for the aquifer nodes as accurately as possible. Certain other nodes in the model are used to simulate 

streams and springs, and these nodes are distinguished from 

nodes that represent aquifers. The model is operated by 

coupling the data describing the physical and hydrologic 

characteristics of each node with the appropriate physical 

and hydrologic flow equations. Computers are used to solve 

the flow equations.

After model calibration is complete, the model will be 

useful for assessing management alternatives. For example, 

the effects of pumping can be simulated at various nodes 

for various time periods, and the resulting impact on streams, 

springs, and stored ground water can be predicted using the 

model. The current model for the Piceance basin is not completely calibrated because onsite data are insufficient to assign 

accurate permeability and storage values to all model nodes. 

Additional permeability and storage values are being compiled by aquifer testing, a field technique in which water is 

pumped from or injected into the aquifer. The response of 

the aquifer is used to derive the needed values. Eventually, 

the model will be used to make quantitative predictions concerning the hydrologic effects of future mine drainage.
E VA PO TRA NSPIRA TION

Precipitation, either snowmelt 

or rainfall, supplies the flow 

system

Water moves in the downstream direction as streamf low, in the alluvial aquifer as underflow, and 

in bedrock aquifers as regional 

flow

Water migrates to 

the stream valley as surface runoff, 

minor flow in the 

unsaturated zone, 

and movement 

through bedrock 

aquifers n

C/5

H1

Not to scale Bedrock aquifers may not discharge into the 

alluvium as shown in reaches of the valley 

where the alluvium is mostly clay

Natural flow system along Piceance and Yellow Creek valleys (fig. 48).
74 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

THE DOCTRINE OF PRIOR APPROPRIATION 

IS USED TO ALLOCATE SURFACE WATER, 

SPRING WATER, GROUND WATER, AND 

RESERVOIR WATER IN COLORADO

SURFACE WATER

The Constitution of the State of Colorado provides, in 

Article XVI, "The water of every natural stream, not 

heretofore appropriated, within the State of Colorado, is 

hereby declared to be the property of the public." In Colorado, an appropriation may be initiated by diverting the 

water and consummated by applying the water to a 

beneficial use. However, an appropriation by itself is not 

a water right. A valid water right requires that the appropriation be adjudicated in the water court of that water 

division. There are seven water divisions in Colorado which 

correspond approximately to the major drainage basins in 

the State.

Because water is in short supply in Colorado, a method 

for determining the priority of water rights was established. 

This method is the Doctrine of Prior Appropriation. Under 

the Doctrine, early water rights have priority for diversion

and use of water, compared to water rights established at 

a later date. The State Engineer is responsible for administering the water rights in Colorado. The holder of a senior 

water right has the prerogative to satisfy the full amount 

of his decreed water right before any junior water rights are 

allowed to divert and use the water.

A water right does not guarantee, however, that the water 

is available for diversion. In times of average precipitation 

and streamflow, only the holders of senior water rights may 

have the opportunity to divert all or part of their appropriation. Conversely, the holders of junior water rights may have 

the opportunity to divert their appropriation only rarely, 

when precipitation and streamflow are extremely high.

SPRINGS

Water discharging from a spring normally can be allocated 

in a manner similar to that for surface water. After diverting the spring water and applying the water to a beneficial 

use, the appropriation can be adjudicated to obtain a water 

right. In the Piceance basin the water rights for surface water 

and springs are held by various government agencies, irrigation companies, mineral companies, and ranchers.

GAINS

Measurements

Uncertain

-2

-3

LOSSES

-4

50 45 40 35 30 25 20 15

DISTANCE FROM MOUTH, IN MILES

10

Cams and losses along selected reaches of Piceance Creek, March 26, 1981 (fig. 49).
A stream node simulates 

the stream in the top layer. 

Valley-fill alluvium is not modeled

Layer

The upper aquifers are represented 

by two layers of nodes in which one layer has horizontal permeability that 

varies according to direction, and both layers have slightly decreased 

vertical permeability

A confining layer, the Mahogany 

zone, is represented by a layer of 

nodes of minimal permeability

The lower aquifers are represented 

by two layers of nodes that have 

greatly decreased vertical permeability

The model solves the hydraulic 

flow equation in each node 

block and combines the 

solutions

The model simulates the flow 

of naturally recharged water 

through the aquifer system and to streams

A calibrated model can be 

used to predict the effects 

of pumped wells on streamflow 

and water stored in the 

aquifers

n 

%CO

Framework for ground-water model of Piceance basin (fig. 50).
76 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

GROUND WATER

Colorado distinguishes between tributary and nontributary ground water in the administration of its groundwater resources. The Doctrine of Prior Appropriation applies to ground water that is hydraulically connected to 

streams. Water that naturally discharges from aquifers to 

streams is called tributary ground water because it contributes to streamflow as a tributary stream does to a larger 

stream. Wells completed in tributary aquifers probably 

derive pumped water from several sources:

1. Water in the aquifer that would otherwise discharge 

to the stream; this reduces streamf low.

2. Water from streams that is induced into the aquifer 

as a consequence of pumping; this also reduces 

streamf low.

3. Ground water in storage.

The sources of water described in items 1 and 2 affect appropriated water in the streams and therefore are regulated 

using the Doctrine of Prior Appropriation.

Ground water that does not discharge naturally into 

streams is called nontributary ground water. It is administered separately from tributary ground water. Nontributary ground water is administered by the State Engineer 

on the basis of the date of appropriation and the volume 

of water in storage in the aquifers. Those holding senior 

water rights (based on earlier dates of appropriation in that 

system) can pump water from wells in preference to those 

holding junior water rights (based on later dates of appropriation). However, in the absence of competing water 

rights, a landowner is allowed to pump, in any year, a maximum of 1 percent of the volume of ground water stored 

below his land. Therefore, the ground-water supply should 

last 100 years.

SURFACE RESERVOIRS

The Doctrine of Prior Appropriation also applies to surface reservoirs. Whether the reservoir is onstream or offstream, it may be filled only when the water right of the 

reservoir is in priority. As a general rule, reservoirs are 

allowed one filling annually.

WATER FOR OIL-SHALE DEVELOPMENT 

WILL BE REGULATED BY THE 

STATE OF COLORADO

Water supplies will be required for the development of 

oil shale and associated minerals. At least part of these supplies will be obtained from streams and springs, provided

that an adequate water right is obtained by appropriation 

and adjudication. Alternatively, a water supply from a 

stream or spring might be obtained by:

1. Purchasing a water right;

2. Purchasing water from the owner of a water right; or

3. Purchasing water from another source that can be used 

to augment the flow of the stream or spring, thereby 

replacing the water taken illegally.

Water supplies also may be obtained using the water drained from the mines. However, in many areas, part of the water 

drained from the mines eventually will be depleted from the 

streams as a consequence of mine drainage. This depletion 

cannot interfere with the water rights of others; it must be 

allocated by means of a water right, purchased water, or 

augmentation plan.

Deep ground-water reservoirs that lie stratigraphically 

below the oil-shale aquifers also may furnish water for oilshale development. If these reservoirs are judged by the State 

Engineer of Colorado to contain nontributary ground water, 

the water will be allocated by the appropriate system of water 

rights, or by the rule that allows the pumpage of 1 percent 

of water stored in the ground-water reservoir in any year.

Surface-water reservoirs may be constructed in the Piceance basin to store water supplies and to insure that an 

adequate supply is available when needed. The filling of 

these reservoirs must be within the priority system.

REFERENCES

Redosovich, G. E., and Hamburg, D. H., compilers and eds., 1971, Colorado water laws, compacts, treaties, and selected cases; report prepared 

for Colorado State Engineer, Division of Water Resources, Colorado 

Department of Natural Resources: Denver, Colo., 205 p.

State Engineer of Colorado, 1978, Water rights inventory map for the oil 

shale development area of northwestern Colorado: Denver, Colo., 4 

maps; scale 1:53,300.

Trescott, P. C., and Larson, S. P., 1976, Documentation of finite-difference 

model for simulation of three-dimensional ground-water flow: U.S. 

Geological Survey Open-File Report 76-591, 21 p.

U.S. Geological Survey, 1979, Water resources data for Colorado, Vol. 

2. Colorado River Basin above Dolores River: U.S. Geological Survey 

Water-Data Report CO-79-2, 397 p.

____1980, Water resources data for Colorado, Vol. 3. Dolores River 

Basin, Green River Basin, and San Juan River Basin: U.S. Geological 

Survey Water-Data Report CO-79-3, 438 p.

Weeks, J. B., Leavesley, G. H., Welder, F. A., and Saulnier, G. J., Jr., 

1974, Simulated effects of oil-shale development on the hydrology of 

Piceance basin, Colorado: U.S. Geological Survey Professional Paper 

908, 84 p.

The water quality of a stream is determined by the 

suspended and dissolved constituents. The suspended sediment in Piceance Creek and possible erosional hazards 

related to mineral development in the basin are described 

in the following chapter.
SUSPENDED SEDIMENT IN PICEANCE CREEK

By VERNON W. NORMAN

Sediment is probably the most visible water-quality 

characteristic of streams in the Piceance basin. The more 

sediment suspended in the water, the more turbid or muddy 

the stream appears. In addition, the characteristics of the 

landscape, such as steep hillsides, valley floors, alluvial fans, 

and gullies are the result of sediment erosion, transport, and 

deposition.

Hillside erosion near Rio Blanco after rainstorm, July 18, 1976 

(fig. 51).

Erosion and the transport of suspended sediment by 

streams are natural processes that, in some circumstances, 

may have undesirable consequences:

1. The aquatic environment may deteriorate, which could 

damage or destroy life in the stream.

2. Water treatment may be required before the stream 

water can be used for some purposes.

3. Surface reservoirs may lose their storage capacity 

because of sediment deposition.

4. Toxic metals and organic substances that are relatively 

insoluble in water may be adsorbed on the surface of 

sediments and transported with the sediment.

5. The appearance of the stream is impaired.

SEDIMENT TRANSPORT IS THE RESULT 

OF NATURAL PROCESSES

Under natural conditions, sediment in the streams is 

derived from erosion of soils on the hillsides or from the 

bed or banks of the stream channels. Soils on the hillslopes are usually thin, and in many places have coarse particles on the surface. The coarse particles slow the erosion 

caused by rainfall. Hillslope soils erode readily only on steep 

slopes, during intense rainfall, or where the land has been 

disturbed. The sediment particles are carried to the streams 

by overland flow resulting from snowmelt during the spring 

or from rainstorms during the summer.

The banks of the main streams, such as Piceance and 

Black Sulphur Creeks, are generally composed of sand, silt, 

and clay particles that are less than about one-tenth of an 

inch in diameter. These materials erode easily when stream 

discharge increases due to snowmelt runoff or summer 

storms. Bank erosion is probably most prominent during 

the spring snowmelt when increases in stream discharge persist for many days. The bank material absorbs a large 

amount of water, becomes soft and easily removable, and 

sloughs into the stream in large clumps.

The streambed of Piceance Creek is composed of silt, 

sand, gravel, and occasional cobbles, with pockets of fine 

material where the velocity of the stream generally is slow. 

Coarse streambed materials normally move only during 

high flows in spring or during flooding from summer 

storms.

77
78 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

SEDIMENT TRANSPORT IN STREAMS 

DEPENDS ON THE AMOUNT AND 

DURATION OF STREAMFLOW

Streams in the Piceance basin are either perennial (flow 

all year), intermittent (flow for 1 or 2 months during the 

spring), or ephemeral (flow only in response to rapid snowmelt or thunderstorms). The majority are ephemeral, and 

sediment carried by them commonly does not reach the major or perennial streams except as a result of large or intense 

storms. Ephemeral streams may carry sediment only short 

distances during each flood and also may deposit fans of 

material at their mouths on entering a larger valley or 

stream. Intermittent streams may carry the sediment much 

farther downstream because their flow is sustained for 

several weeks. Perennial streams carry the sediment much 

farther and can transport most of the fine particles out of 

the basin in a few days. The coarse sand and larger particles move more slowly and require years, decades, or 

longer to move through the streams and out of the basin.

Daily sediment records have been collected since 1974 at 

24 sites in the Piceance basin. The annual total sediment 

loads at these sites range from 0 to more than 290,000 tons. 

Zero values are recorded for years in which an ephemeral 

stream did not flow. The greatest load was measured at the 

mouth of Yellow Creek during an extreme flood; more than 

99 percent of the 290,000 tons passed the site within 7 hours 

on September 7, 1978. During the period of record, perennial streams have transported from 100 to 60,000 tons per 

year.

If the drainage area above a gaged site is known, the sediment yield in tons per square mile can be determined and 

used to compare the volumes of sediment from different 

areas. In basins drained by perennial streams, sediment 

yields generally range from 20 to 80 tons per square mile; 

average yields from most basins are about 30 tons per square 

mile. In basins drained by ephemeral streams, measured 

volumes range from 0 to 170 tons per square mile during 

a short period of record. These volumes are about 10 times 

smaller than the sediment yields predicted for the same areas 

before the yields were measured. The difference probably 

is due to the large volume of sediment that was eroded but 

will not reach the streams except during an extreme flood. 

Consequently, if sediment yields are measured for a longer 

period that includes some extreme floods, measured yields 

may be closer to predicted yields.

Turbid water in Piceance Creek near Rio Blanco, July 17, 1977

(fig. 52).

Coarse sediment deposited on highway near Piceance Creek during intense rainstorm, July 19, 1977 (fig. 53).

THE SEDIMENT AND CHANNEL 

CHARACTERISTICS OF THE 

PICEANCE BASIN ARE UNUSUAL

Some characteristics of sediment in the Piceance basin are 

unusual. For example:

1. Much of the sediment of sand size and larger is flat, 

plate shaped, and of low density. Streams can carry 

this material farther than they carry more spherical 

grains.
SUSPENDED SEDIMENT 79

SPRING RUNOFF

EPHEMERAL STREAM

INTERMITTENT STREAM

JAN FEE MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC

Typical yearly distribution of sediment load in streams in the Piceance basin (fig. 54).

2. Gullies caused by erosion of the valley floors are 

discontinuous and deep and do not extend the full 

length of the valley.

3. Streambeds eroded by clear water from mine-drainage 

wells and settling ponds have vertical banks because 

the horizontal plate-like particles form a rigid structure that erodes more easily from the sides than from 

the top.

SEDIMENT TRANSPORT RELATED TO 

MINING AND WASTE DISPOSAL 

NEEDS TO BE CONTROLLED

Mining development and waste-disposal activities may increase erosion and result in increased sediment transport. 

For example, surface mining and underground mining create 

temporary piles of stored waste material that may or may
80 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Deeply cut channel in streambed of Corral Gulch, resulting from 

well discharge, April 3, 1978 (fig. 55).

not be backfilled after mining activities are complete. The 

waste material stored on the land surface or backfilled into 

open-pit mines is more easily eroded than the undisturbed 

soil mantle.

A spoil pile of retorted oil shale may be finely pulverized 

material, which also will be easily eroded. This material is 

different from the natural sediment that reaches streams in 

size, shape, composition, and ability to adsorb metals and 

organic substances.

Reclamation procedures to insure that sediment-transport 

problems do not develop include:

1. Placement of waste material in spoil piles that have 

flat shapes to reduce erosion.

2. Construction of settling ponds to intercept surface 

runoff passing over easily eroded materials.

3. Compaction of backfilled waste material and spoil 

piles in order to decrease the erosion.

4. Replacement and revegetation of soil over backfilled 

waste material or spoil piles.

A dense vegetation cover greatly reduces erosion.

The chemical effects of spoil piles are discussed in the 

chapter "Chemical effects and control of leachates from oilshale spoil piles."

REFERENCES

Frickel, D. G., 1978, Hydrologic and geomorphic data from the Piceance 

basin, Colorado, 1972-77: U.S. Geological Survey Open-File Report 

78-825, 169 p.

Frickel, D. G., Shown, L. M., and Patton, P. C, 1975, An evaluation of 

hillslope and channel erosion related to oil-shale development in the Piceance basin, northwestern Colorado: Colorado Water Resources Circular 

30, 37 p.

The dissolved constituents in ground water and streams 

result from various chemical processes related to the hydrologic flow system. Relations between the dissolved constituents and the flow system are described in the following 

chapter.
WATER QUALITY IN THE PICEANCE BASIN

By ROBERT L. TOBIN

PERCOLATING GROUND WATER DISSOLVES 

MINERALS FROM THE UINTA FORMATION, 

GREEN RIVER FORMATION, AND 

VALLEY-FILL ALLUVIUM

Snowmelt and rain recharge the bedrock aquifers and 

replenish the ground water that migrates through the Uinta 

and Green River Formations. As the water percolates 

through these formations, minerals are dissolved and ionexchange reactions occur.

In the northern part of the basin, the ground waters and 

their dissolved minerals discharge to springs, streams, and 

valley-fill alluvial aquifers in various reaches of the Piceance 

and Yellow Creek valleys. The exact location and extent of 

hydrologic connections between aquifers and streams are 

not well known. In the southern part of the basin, the Uinta and Green River aquifers discharge to springs, some of 

which contribute to streamflow in the Roan and Parachute 

Creek valleys. Throughout the basin, water in the valleyfill alluvial aquifers also dissolves minerals from the 

alluvium, undergoes ion-exchange reactions, and in some 

places discharges to surface water.

DISSOLVED MINERALS DIFFER IN THE TWO 

MAJOR BEDROCK AQUIFERS OF THE 

UINTA AND GREEN RIVER FORMATIONS

The water chemistry of the upper bedrock aquifers is dominated by dissolved calcium, magnesium, and bicarbonate 

along the rim of the basin; and by sodium, magnesium, 

bicarbonate, and sulfate in the central part of the basin. These 

constituents are characteristic of water in the upper aquifers, 

principally the Uinta Formation. Sodium and bicarbonate 

are the dominant dissolved constituents in the water from 

the upper Parachute Creek Member of the Green River Formation, at the base of the upper aquifers. The total concentration of dissolved constituents in the upper aquifers generally is lower than 1,000 milligrams per liter. Characteristic 

trace elements include strontium in concentrations of several 

milligrams per liter in the Uinta Formation, and fluoride in 

concentrations of greater than 1 milligram per liter in water 

samples from the lower part of the upper aquifers.

The principal dissolved constituents in water from the 

lower bedrock aquifers are sodium and bicarbonate. The

total concentration of dissolved constituents may range from 

slightly less than 1,000 milligrams per liter along the rim of 

the basin to perhaps 10 or 20 times higher near the northcentral part of the basin. These high concentrations result 

from contact of water with the ancient evaporite deposits 

of nahcohte, dawsonite, and halite associated with the Green 

River Formation. The trace element fluoride also has been 

detected in unusually high concentrations, ranging from 10 

to 30 milligrams per liter in the lower aquifers. The trace 

elements barium, boron, and lithium are abundant in the 

lower aquifers where chloride concentrations also are greater 

than several hundred milligrams per liter.

Methane and hydrogen sulfide gases have been detected 

in many wells that penetrate the aquifers of the Green River 

Formation. These gases probably are generated in the upper and lower aquifers from the alteration of organic matter in an oxygen-depleted environment.

WATER QUALITY IN PICEANCE AND 

YELLOW CREEKS IS AFFECTED BY WATER 

DISCHARGED FROM AQUIFERS

Within the Piceance and Yellow Creek drainage basins, the 

quality of the surface water and ground water are related, 

except during periods of extensive runoff due to storms and 

snowmelt, when streams are freshened. During other 

periods, approximately 80 percent of the annual flow of Piceance and Yellow Creeks originates as discharge from 

alluvial and bedrock aquifers. During steady-flow conditions 

on March 26,1981, analysis of the major dissolved constituents at numerous sites in Piceance Creek generally indicated 

increases in the downstream direction. The concentrations 

of dissolved solids, bicarbonate, sulfate, and sodium increased due to the discharge of water from the bedrock aquifers 

to the stream valley and tributaries.

The Piceance Creek has been divided into reaches; the flow 

regime in each is generalized by comparing the calculated 

gains and losses of flow (fig. 58) with changes in stream 

quality. The total load of dissolved constituents in Piceance 

Creek increased from about 1.5 tons per day near the headwaters of the stream to about 122 tons per day near the 

mouth. The increase in volume of dissolved constituents in 

the downstream direction indicates that Piceance Creek is 

transporting large quantities of dissolved minerals into the 

White River valley.

81
Lower aquifers Upper aquifers Lower aquifers Upper aquifers

O O3

O

3

Q) o' cr

a.CU

.a

c

oo

S)

L A J

85LD

i

85
WATER QUALITY 83

In the Alkali Flats area, several miles downstream from 

Dry Fork, the bicarbonate concentration in Piceance Creek 

increases by several hundred milligrams per liter. This 

change in surface-water quality is caused by the discharge 

of ground water upward through an extensive fracture zone. 

Salts precipitated on the land surface by evaporation of the 

shallow ground water are visible for many miles during the 

low-flow season. A similar area of precipitated salts is found 

near the mouth of Yellow Creek. During periods of higher 

flows, the accumulated salts on the flood plains are flushed 

into Piceance and Yellow Creeks.

The water-quality patterns in Piceance Creek are easily 

observed during intermediate and low-flow conditions in the 

winter and nonirrigation periods. Substantial changes in 

dissolved-solids composition and concentrations are observed during the periods of intense surface runoff and during the irrigation season. Dissolved-solids concentrations 

generally are much lower during intense runoff because they 

are diluted by precipitation; concentrations are considerably

higher during the irrigation season because of the addition 

of minerals dissolved by water applied to fields.

The effects of mine drainage on water quality at tracts 

C-a and C-b (fig. 23) were analyzed using a solute-transport 

model. The analysis did not consider the disposal of water 

drained from mines only the hydrologic and chemical effects of the pumping on the aquifers and streams. The model 

predicted that mines at tract C-a could be drained by pumping only the lower bedrock aquifers; the water in the upper 

bedrock aquifers would drain downward in response to 

pumping the lower aquifer. The quality of the ground water 

in the lower aquifers near tract C-a would improve with 

pumping because the less mineralized water in the upper 

aquifers would dilute the more mineralized water in the 

lower aquifers. Pumping also reduces the period of contact 

between the water and soluble minerals and results in less 

solution compared to natural conditions. Distant from tract 

C-a the model predicted total dissolved constituents that are 

related to changes in the flow system caused by pumping.

Alkali flats, marked by white salts on the land surface in Piceance Creek valley, with White River valley in the background (fig. 57).
OO

1400

Reach in which stream and valley-fill alluvium exchange water

1200

1000

800

2 600

400

200

Reach in which water in bedrock aquifer passes through fractures and resulting 

springs discharge into creek. Tributaries that discharge into creek also receive discharge from springs

Reach in which stream and valleyfill alluvium exchange water Reach in which water in bedrock aquifers passes 

through fractures and resulting springs 

discharge into 

creek

40

3530

2520

15

10

m ?o

8

2

I

TJ

n

m >

I

40 30 20 

DISTANCE FROM MOUTH OF STREAM, IN MILES

10

Flow and water-quality variations in Piceance Creek, March 26, 1981 (fig. 58).
WATER QUALITY 85

At tract C-b, the model predicted that:

1. Both bedrock aquifers would need to be pumped to 

drain the mines, and

2. The changes in water quality in the bedrock aquifers 

would be similar to the changes at tract C-a.

A reduction in streamflow and an increase in dissolved 

solids in most reaches of the streams also were predicted by 

the model. After mining activity is completed, the pumps 

will be shut off and the hydrologic system will recover. The 

model also was used to predict the effects of solution by 

water flooding the abandoned mines. The model indicated 

that solution of soluble minerals in the abandoned in situ 

retorts will increase the dissolved-solids concentrations in 

ground water near the mines, especially in aquifers of high 

permeability.

REFERENCES

Robson, S. G., and Saulnier, G. J., Jr., 1980, Hydrogeochemistry and 

simulated solute transport, Piceance basin, northwestern Colorado: U.S. 

Geological Survey Professional Paper 1196, 65 p.

Weeks, J. B., Leavesley, G. H., Welder, F. A., and Saulnier, G. J., Jr., 

1974, Simulated effects of oil-shale development on the hydrology of 

Piceance basin, Colorado: U.S. Geological Survey Professional Paper 

908, 84 p.

Welder, F. A., and Saulnier, G. J., Jr., 1978, Geohydrologic data from 

twenty-four test holes drilled in the Piceance basin, Rio Blanco County, 

Colorado, 1975-76: U.S. Geological Survey Open File Report 78-734, 

132 p.

A study of organisms in streams provides a rapid method 

of appraising the health of a stream and its ability to sustain higher forms of plant and animal life. A description 

follows of some of the organisms in Piceance Creek.

APPRAISAL OF WATER QUALITY IN PICEANCE CREEK 

USING BENTHIC INVERTEBRATES

By KENNETH J. COVAY

The water quality of a stream depends on the dissolved 

and suspended constituents in the water. Periodic sampling 

and analyses of these constituents is one way to assess the 

stream quality. Another method is to relate the response of 

living organisms in the aquatic environment to natural and 

man-induced changes in water quality. For example, benthic invertebrates (animals lacking a backbone, such as insects) respond to contamination. In particular, short-term 

exposures to contamination, which might not be detected 

by chemical sampling, may be discovered in samples of benthic invertebrates because the effects of changes in water 

quality on organisms persist for several weeks or months.

BENTHIC INVERTEBRATES

ARE IMPORTANT FORMS OF LIFE

IN THE AQUATIC ENVIRONMENT

The aquatic environment is host to a variety of organisms 

ranging from the lowest forms of microorganisms, such as 

bacteria and algae, to the higher forms of plants and animals, 

including insects and fish. The bottom of a stream is a 

habitat for all these types of life, of which benthic invertebrates are one of the most important. Bottom-dwelling 

organisms primarily consist of the immature forms of insects, but also include noninsects such as snails, clams, scuds 

water mites, worms, and leeches.

Benthic invertebrates are a significant link in the aquatic 

food chain they occupy a place in the transfer of food between the primary source, plants, and the end of the food 

chain, man or similar animals. Benthic invertebrates are the 

primary source of food for fish and other aquatic vertebrates. Water-quality degradation or loss of benthic habitat 

will interrupt feeding patterns and cause an instability in 

all aquatic populations and communities.

BENTHIC INVERTEBRATES CAN BE USEFUL 

IN ASSESSING WATER-QUALITY CONDITIONS

Among the methods used to assess the water-quality conditions in streams is the analysis of bottom-dwelling animals.

Benthic invertebrates are good indicators of water quality 

because they are:

1. Sensitive to changes in their environment.

2. Somewhat immobile, and thus do not easily move 

away from areas of contamination.

3. Relatively long lived and able to reflect temporary contamination that is difficult to detect by chemical 

sampling.

Different benthic invertebrates are associated with different water-quality conditions. Immature forms of caddisflies, stoneflies, and mayflies usually are found in 

uncontaminated water because they require substantial concentrations of dissolved oxygen. Worms, leeches, and some 

immature two-winged flies can survive in water containing 

very little dissolved oxygen, and large numbers of these 

organisms commonly are found in contaminated streams. 

Groups of benthic invertebrates indicate water quality 

because different types of benthic invertebrates are associated with different water conditions. For example, 

changes of benthic-invertebrate groups compared to relative changes in concentration of dissolved oxygen are illustrated below.

Dissolved oxygen, however, is not the only factor that 

influences the establishment of benthic-invertebrate communities. The community is a result of the interactions between numerous physical and chemical factors. For example, 

stream-bottom characteristics, stream velocity, water 

temperature, dissolved substances, and the incidence of 

droughts and floods are all factors that regulate the occurrence and distribution of benthic invertebrates.

In a stream that is not contaminated, benthic communities 

usually consist of many different types of benthic invertebrates with no single type particularly dominant. A 

contaminated stream might contain only a few types with 

many individuals of each type. The benthic invertebrates 

living in the contaminated water are those that can tolerate 

such conditions. In general, members of the two-winged fly 

order have greater tolerances to extremes in water-quality 

conditions than do members of other groups. As previously 

mentioned, the presence of only a few organisms such as 

worms and leeches also indicates contaminated water.

87
88 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

BENTHIC INVERTEBRATES 

MOLLUSC: ARTHROPODA:

1. Insects (flies)

2. Crustaceans (scuds)

3. Arachnids (mites)

ANNELIDA:

1. Worms

2. Leaches

ANIMAL KINGDOM

Benthic invertebrates as part of the animal kingdom (fig. 59).

Normally flowing uncontammated streams have large concentrations of dissolved oxygenThe concentration of dissolved oxygen in streams is 

decreased by contamination and the composition of 

the benthic communities is changed

The concentration of dissolved oxygen in streams eventually increases

UPSTREAM

More

Less ,

DISSOLVED 

OXYGEN 

CURVE

BOTTOM 

ANIMALS

Clean 

water

Origin ofContamination

Transition Contaminated water Transition Clean

water

DOWNSTREAM

1 . Caddisfly 5. Two-winged fly (maggot)

2. Stonefly 6. Worms

3. Two-winged fly (bloodworm) 7. Mayfly

4. Snail

Changes in dissolved-oxygen concentration in streams and related changes in groups of benthic invertebrates (fig. 60).
APPRAISAL OF WATER QUALITY USING BENTHIC INVERTEBRATES 89

INSECTS

Water beetle Larva of true fly

r

Mayfly

Stonefly

Dragonfly

Caddisflies

NONINSECTS

Scud Earthworms

Snail Leeches

Benthic invertebrates that live in the bottom of streams (fig. 61).
90 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

108W

15 MILES

0 5 10 15 KILOMETERS

EXPLANATION 

SITE LOCATION

1. Piceance Creek downstream 

from Rio Blanco

2. Willow Creek near Rio 

Blanco

3. Piceance Creek upstream 

from Hunter Creek, near 

Rio Blanco

4. Black Sulpur Creek near 

Rio Blanco

5. Piceance Creek downstream 

from Ryan Gulch, near 

Rio Blanco

6. Piceance Creek at White 

River

Samples of benthic invertebrates collected at six locations in the 

Piceance Creek basin (fig. 62).

TYPES OF BENTHIC INVERTEBRATES 

IN THE PICEANCE BASIN

Samples of benthic invertebrates were collected at six locations along Piceance Creek. Approximately 26 samples were 

collected at each location mostly during the summer and 

fall. The composition of these samples is illustrated using 

circular graphs. Each graph indicates the proportion of major insect and combined noninsect groups and permits comparison between sites. Insect groups identified in the Piceance 

basin are the two-winged flies, mayflies, stoneflies, caddisflies, beetles, true bugs, and dragonflies. Noninsect groups 

identified are aquatic worms, scuds, snails, water mites, and 

leeches. The site number for each circular graph is keyed 

to the site number on the map.

The circular graphs show a gradual increase in twowinged flies in Piceance Creek in the downstream direction 

from site 1 (downstream from Rio Blanco) to site 6 (at White 

River). This increase probably can be attributed to chemical 

changes in the water and physical changes in the bed 

materials. For example, during the summer months when 

land is irrigated, the concentration of dissolved solids increases downstream because the irrigation water dissolves 

minerals from the soil and alluvium as it returns to the 

stream. The concentration of dissolved solids can be three 

times greater at site 6 than at site 1 because of the irrigation 

water return flow and the natural discharge of bedrock and 

alluvial aquifers to the stream.

Downstream increases in sodium, bicarbonate, and sulfate 

are major contributors to the increases in dissolved solids. 

Concentrations of ammonia, boron, and, at times, fluoride, 

also increase at site 6. The streambed at site 6 is composed 

of finer sized materials than at site 1, contributing to increasing stream turbidity and suspended-sediment concentrations 

downstream.

The composition of benthic invertebrates at sites along 

Piceance Creek normally does not vary greatly from season 

to season. However, during intense periods of runoff, the 

communities may be changed or destroyed by the scour 

resulting from increases in stream discharge and deposition 

of sediment. Also, the communities may become dormant 

during sustained periods of cold weather.

DISCHARGE OF OIL-SHALE WASTES 

INTO STREAMS OF PICEANCE BASIN 

MAY CHANGE THE COMPOSITION OF THE 

BENTHIC-INVERTEBRATE COMMUNITY

It has been shown that the composition of benthic communities is affected by changes in water quality. However, 

the effects of oil-shale development on benthic-invertebrate 

communities have not been fully determined.

Oil-shale development is likely to cause increased concentrations of suspended sediment, organic compounds, dissolved solids, and various inorganic compounds such as 

ammonia, boron, and fluoride. These constituents are discussed in the chapters "Suspended sediment in Piceance 

Creek," "Water quality in the Piceance Basin," "Chemical effects and control of leachates from oil-shale spoil piles," and 

"Chemical effects and control of wastes from in situ retorts."

Changes in the physical and chemical characteristics of 

stream water due to oil-shale development will likely result 

in changes in the composition of the benthic-invertebrate 

community. This is based on the fact that the increase of 

dissolved-solids concentration and suspended sediment 

downstream coincides with an increase in tolerant organisms 

of the two-winged fly order and a decrease in less-tolerant 

organisms.
APPRAISAL OF WATER QUALITY USING BENTHIC INVERTEBRATES 91

SITE 1

SITE 2

Beetles

Mayflies

True bugs

Dragonflies

SITE 4

SITE 5

Stoneflies

SITE 3

Caddisflies

Site numbers refer to sampling points 

along Piceance Creek, as shown on 

figure 62

SITE 6

Proportions of benthic organisms along Piceance Creek (fig. 63).
92 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Water needed for oil-shale development may be taken 

from local streams and pumped from mines during drainage 

activities. Additional water supplies may be developed from

regional aquifers that occur stratigraphically beneath the oil 

shale and associated minerals, as indicated by the following discussion.
PLANNING FOR MINERAL DEVELOPMENT: 

ALTERNATE WATER SUPPLIES AND EFFECTS OF RETORTS

PALEOZOIC AND MESOZOIC FORMATIONS AND THEIR POTENTIAL

AS GROUND-WATER RESERVOIRS

By MARJORIE E. MACLACHLAN and FRANK E. WELDER

DEEP GROUND-WATER RESERVOIRS 

MAY BE USED TO FURNISH WATER 

SUPPLIES OR TO STORE WASTEWATER

Development of oil shale and associated minerals, accompanied by related population and industrial growth, will increase water demands in northwestern Colorado. Cost 

estimates are as much as one billion dollars for providing 

a water supply from streams and surface reservoirs. 

Preliminary hydrologic studies of the Green River and Uinta 

Formations in the Piceance basin indicate that millions of 

acre-feet of ground water may be present in these underground reservoirs. However, deep ground-water reservoirs 

that may lie stratigraphically beneath the Green River Formation in Paleozoic and Mesozoic formations have not been 

explored or tested for storage, yield, and water quality.

A thorough understanding of all potential aquifers, deep 

and shallow, will allow the most economical development 

of new supplies. Exploratory drilling may locate large 

ground-water reservoirs and reduce the need for the construction of costly dams, canals, pipelines, and pumping stations that are required for surface-water supplies. Deep 

ground-water reservoirs may not only constitute a valuable 

alternative or supplemental water supply, but also can serve 

as possible storage sites for injected wastewater.

GEOLOGIC EVIDENCE INDICATES THAT 

DEEP FORMATIONS IN PICEANCE BASIN 

MAY BE AQUIFERS

Exploratory drilling for oil and gas along the margins of 

structural basins of northwestern Colorado has provided 

limited information on the subsurface characteristics of the 

geologic formations. Additional studies have been made of 

formations exposed at the surface. The information indicates 

that aquifers of Paleozoic and Mesozoic age may lie adjacent to the Piceance basin, at depth within the Piceance

basin, and in northwestern Colorado in general. The range 

in depth of these aquifers resulted from erosion and from 

the structural deformation described in the chapter "General 

geology of the Piceance basin."

A discussion of the sedimentary sequence of Paleozoic and 

Mesozoic formations follows. It includes descriptions of the 

water-supply potential of several formations based on 

geologic and hydrologic information.

PALEOZOIC AND MESOZOIC FORMATIONS 

ARE SHOWN ON THREE 

STRATIGRAPHIC COLUMNS

Different types of Paleozoic and Mesozoic rocks are found 

in different places around the margins of the Piceance basin. 

Three stratigraphic columns show their sequence, age, name, 

rock type, and thickness along the Grand Hogback, on the 

east side of the Piceance basin; near the Yampa River, north 

of the Piceance basin; and near Grand Junction, on the 

southwest side of the Piceance basin.

Unconformities that are shown in the stratigraphic columns indicate that certain formations and parts of formations are missing. Attempts to drill exploratory holes to 

certain formations need to take into account nearby stratigraphic columns, to be certain that the formation interval 

is present beneath the drilling site. Unconformities also 

separate the oldest unit shown in each of the three columns 

from underlying Precambrian rocks. The youngest unit 

shown in each column is unconformably overlain by Tertiary rocks that are discussed in the chapter "General geology 

of the Piceance basin." About 25,600 feet of Paleozoic and 

Mesozoic rock is represented in the composite section along 

the Grand Hogback, about 11,600 feet of Paleozoic and 

Mesozoic rock is found near the Yampa River, and about 

10,400 feet of Mesozoic rock (the Paleozoic is absent) is present near Grand Junction.

95
96 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO. 

TABLE 4. Correlation chart showing Paleozoic and Mesozoic formations

STRATIGRAPHIC COLUMN ALONG GRAND HOGBACK STRATIGRAPHIC COLUMN NEAR YAMPA RIVER

UNIT 

SOUTH-NORTH

GENERAL LITHOLOGY 

(THICKNESS IN FEET)

GENERAL LITHOLOGY 

(THICKNESS IN FEET)

Upper

Williams Fork 

Formation

Brown/white sandstone 

coal

gray/black shale;

(4.500)

lies Formation Brown/white sandstone; gray shale, coal

(1.000 to 1.500)

Mancos Shale Gray shale; gray sandstone Mancos Shale

(5.OOO to 6.OOO)

Dakota Sandstone Gray/tan sandstone (125 to 225)

Burro Canyon Formation2 Yellow sandstone; green claystone

Mornson Formati

Upper

(225)

Variegated shale and mudstone; gray sandstone; local gray limestone (500)

Dakota Sandstone 

Cedar Mountain Formation2

Mornson Formation

Middle

Gray/green, glaucomtic sandstone; gray

oolitic limestone (100)

Redwater Member

Curtis Member

Gray/orange, crossbedded sandstone

(75 to 1 00) Entrada Sandstone

Upper

Glen Canyon Sandstone4

Red/mottled sandstone, siltstone, shale; 

gray/brown conglomeratic sandstone

(225 to 560+)

Red-brown, brown-buff shale/siltstone; 

gray dolomite/limestone

(100 to 480+)

ii i in mm imi i in mum mi mi inn

Chmle Formation

State Bridge FormatK

Upper

Mmturn Formation

Belden Formatu

Gray/orange, crossbedded sandstone Glen Canyon Sandstone4

(0 to 75)

Chmle Formation

Moenkopi Formation

nnnnDnnnnnnnQniiniiiii i

Park City Formation

Gray shale; brown/gray calcareous sandstone; coal; bentonite

(5,700)

Gray/ yellow sandstone (about 100)

Gray shale; mudstone, limestone; gray/tan 

conglomerate, sandstone .j.ijP..1 °.?SP^

Variegated mudstone, shale, claystone, 

local conglomerate, sandstone, limestone

_______(up to 650)

Green, glaucomtic shale, siltstone,

oolitic limestone 70 to 300)

Gray, crossbedded, glaucomtic sandstone

("P to 25)

Gray/buff, crossbedded sandstone

(up to 150)

Pink, gray, buff crossbedded sandstone, 

conglomerate, gray chert grit at base

(625+)

Red/gray sandstone, siltstone, claystone, 

shale (2go+)

Red/brown/dark red siltstone/shale;

. m

locally gypsiferous (up to 560) iifflimiinniinunDinDMinnniiiiiinnnDniiini

Gray/yellow shale/siltstone/sandstone;

dolomite, limestone (110 to 150)

Weber-Gray sandstone (2Q ,o 250+)

Maroon Maroon arkosic sandstone, shale, 

siltstone, conglomerate (1,600 to 7,000)

Eagle Valley-Gray siltstone, shale, sandstone, carbonate rocks, gypsum lenses 

Minturn Gray-red sandstone, grit, conglomerate, shale, carbonate rocks 

_________(Eagle Valley + Minturn to 1,900)

Weber Sandstone

Morgan Formation

Gray limestone/shale (550 to 700+)

Gray, white, buff, crossbedded sandstone

(900+)

Red sandstone; gray/lavender limestone; 

gray, red, lavender shale and siltstone. 

Chert lenses

(500+)

Molas Formation Red-brown shale/siltstone; gray chert

(20 to 40)

Round Valley Limestone Gray limestone, gray shale (up to 400)

Doughnut Shale Gray shale; red shale (100)

Humbug Formation Gray/red sandstone; gray limestone;

red black shale _______|up to 230)

Madison Limestone 6

Gray limestone, dolomitic limestone, and 

shale; white quartzite (1 20 to 260+)

Manitou Dolomite

Dotsero Formation

Upper Peerless Formation

Gray/white limestone and dolomitic

limestone___________________(60)

Gray/white sandstone, siltstone, or shale

Brown dolomite; gray shale; limestone 

pebble conglomerate | 8Q to 1 50)

Gray dolomite; limestone/dolomite conglomerate; gray shale_______________(100)

Gray/tan, locally dolomitic limestone

(1 30 to 660)

Gray shale; orange/brown sandstone and 

dolomite (67) Lodore Formation Pink/gray crossbedded sandstone (260+)
PALEOZOIC AND MESOZOIC FORMATIONS AS GROUND-WATER RESERVOIRS

TABLE 4. Continued

97

STRATIGRAPHIC COLUMN NEAR GRAND JUNCTION

UNIT

Hunter Canyon' 

Formation

Mount Garfield 

Formation Buff/gray sandstone; gray shale; coal

(about 1,4BO)

Sego Sandstone Buff/gray sandstone; gray shale

Castlegate/ 

Sandstone\

Mancos Shale Dark-gray shale; gray sandstone

Dakota Sandstone

Burro Canyon Formation2

Morrison Formation

Summerville Formation

Brown/gray sandstone; carbonaceous shale; 

coal (100 to 200;

White/gray/buff sandstone M2H

variegated mudstone and siltstone; 

gray/red/buff sandstone, limestone: 

limestone conglomerate (6OO|

Alternating gray/green/red siltstone/

Entrada Sandstone White/buff/pink crossbedded sandstone

(100 to 300]

ted/buff/gray sandstone; lavender shale/

Wingate 

Sandstone

Buff/red-brown, orange, crossbedded 

^andstone (300 to 400;

Chinle Formation

GENERAL LITHOLOGY 

(THICKNESS IN FEET)

Buff/gray sandstone; gray shale

(375 to 1,400)

(up to 300)

Castlegate: Buff/gray sand- 

 ^ stone; gray shale (0 to 1 30)

(4.000]

sandstone; gray shale (40 to 60]

siltstone (0 to 200]

Red/brown siltstone; lenses of red sandstone/ 

shale; limestone pebble conglomerate

(80 to 120;

Upper

Upper

Upper

Upper

Upper

Upper

Middle/ 

Lower

Silur

Upper

Middle

Upper

Middle/ 

Lower

[Wavy lines indicate unconformities; dashed lines indicate uncertain 

age ranges; and vertical lines show gaps in record]

SOURCES OF INFORMATION: 

ALONG GRAND HOGBACK

Bass and Northrop. 1963; Bryant, 1979; Gaskill and Godwin, 1966; Imlay. 

19BD; Johnson. May. Hansley. Pitman, and Fouch. I960; MacLachlan. 

1972; Murray. 1966: Poole and Stewart. 1964; Ross and Tweto. 1980; 

Tweto. 1976; Tweto. Moench. and Reed. 197B.

NEAR YAMPA RIVER

Imlay. 198D; Hansen. 1965; Hansen and Carrara. 19BO; MacLachlan. 1972; 

Pipiringos and Imlay. 1978: Poole and Stewart. 1964; Rowley and Hansen. 

1979; Rowley. Dyni. Hansen. and Pipiringos. 1979.

NEAR GRAND JUNCTION

Cashion. 1 973: Imlay. 19BO; Johnson and May. 19BD; Lohman. 1965; MacLachlan. 1972; Poole and Stewart. 1964.

1 The Ohio Creek member was recently assigned to the Hunter Canyon Formation as its upper member (Johnson and May. 1980). This member formerly 

was considered a formation of Tertiary age. The Hunter Canyon Formation can 

be distinguished from the Mount Garfield Formation by the character of the 

sandstones. Those of Hunter Canyon Formation are more numerous, coarse, 

gray, and more massive than those in the Mount Garfield Formation.

2The name Cedar Mountain Formation is used north of the Colorado River 

the name Burro Canyon Formation is used south of the Colorado River.

3The boundary between the Upper and Lower Cretaceous Series is 

uncertain.

4The Glen Canyon Sandstone may be equivalent to all or part of the Glen 

Canyon Group (Poole and Stewart. 1964; MacLachlan. 1972.)

5The geographic boundary between use of Madison Limestone and Leadville Limestone is uncertain.
98 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

108o WYOMING 107o 10B°

"T "COLORADO 

V

CAMBRIAN 

From Lochman-Balk, 1972

108o WYOMING 107o

T"COLORADO

ORDOVICIAN 

From Foster, 1972

THE AREAL EXTENT OF PALEOZOIC AND 

MESOZOIC FORMATIONS IS SHOWN 

ON A SERIES OF MAPS

The distribution of Paleozoic and Mesozoic rocks under 

the Piceance structural basin is shown for each system. The 

shaded areas represent the present extent of the rocks of each 

period within the basin; extensive parts have been eroded 

away. Rocks of seven of the periods (Cambrian, Ordovician,

1D9° 41° n r

1D8o WYOMING 107o

"T"COLORADO"

1D9° 41° n r

DEVONIAN 

From Baars, 1 972

108o WYOMING Irj7o

"T "COLORADO"

MISSISSIPPIAN 

From Craig, 1972

and Devonian through Triassic) probably underlie more 

than one-half of the basin area. Silurian formations are absent. Jurassic and Cretaceous rocks probably underlie the 

entire basin area.

CAMBRIAN

The oldest Paleozoic formations are of Late Cambrian age 

and are found in the northern part of the basin. Rock types 

include sandstone, dolomite, and shale, all deposited in a
PALEOZOIC AND MESOZOIC FORMATIONS AS GROUND-WATER RESERVOIRS

108o WYOMING 107o

99

108o WYOMING 107o

"T" 106°

PENNSYLVANIAN 

From Mallory, 1972

0 60 MILES

I ' I

0 60 KILOMETERS

EXPLANATION

AREA WHERE ROCKS OF 

SYSTEM ARE PRESENT

PICEANCE STRUCTURAL 

BASIN

ZERO THICKNESS LINEDashed where approximately located

DIRECTION OF THICKENING

marine environment. The Dotsero Formation is of more 

limited areal extent than the overlying formations because 

it is confined to the White River uplift area. Cambrian rocks 

thicken generally southwestward across the basin to a maximum of about 700 feet near the Utah border.

ORDOVICIAN

The Ordovician rocks are marine deposits that thicken 

southward toward the Colorado River. The Manitou Dolomite thickens southward to more than 200 feet near Aspen. 

The Harding Sandstone and Fremont Limestone thin toward 

the east; they probably are missing from a significant part 

of the basin.

DEVONIAN

Marine sedimentation recommenced in Late Devonian 

time after an intervening erosional period of about 85 million 

years where the Chaffee Formation overlies the Fremont

109° 41° n 

106°

r

PERMIAN 

From McKee and others, 1967

Distribution of Paleozoic rocks under the

Piceance structural basin (fig. 64

above and facing page).

Limestone, and of about 140 million years where the Chaffee Formation rests on the Lower Ordovician Manitou 

Dolomite. The lower part of the Chaffee Formation is a basal 

quartzite overlying dolomite, shale, and quartzite. The upper part of the Chaffee Formation is limestone and dolomite; 

it is locally sandy and conglomeritic. The formation attains 

a maximum thickness of about 300 feet.

The formations of Cambrian, Ordovician, and Devonian 

age may include aquifers within the sedimentary sequence 

of limestone, dolomite, sandstone, and shale. However, the 

potential for obtaining water supplies from these formations 

has not been investigated.

MISSISSIPPIAN

Lower Mississippian marine carbonate rocks of the Leadville or equivalent Madison Limestone account for most of 

the Mississippian age rocks in the basin. Upper Mississippian shale, limestone, and sandstone of the Humbug 

Formation and Doughnut Shale underlie only the northwesternmost part of the basin. The Mississippian thickens 

westward to about 600 feet near the Utah border.
100 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Water draining from the Leadville Limestone, flowing into Rifle Creek and over Rifle Falls (fig. 65).
PALEOZOIC AND MESOZOIC FORMATIONS AS GROUND-WATER RESERVOIRS 101

Water movement and chemical solution have increased 

the porosity and permeability of the Leadville or Madison 

Limestones more than that of other formations. Exposures 

of the formations contain caves, fractures, mineral-lined 

cavities, and springs. A 9,360-foot deep oil well near 

Rangely, Colo., reportedly yielded saltwater under pressure 

from the Madison Limestone. If the formation is recharged 

by precipitation in the White River uplift, it may store and 

transmit large quantities of water below the oil-shale deposits 

of the Piceance basin. In the White River uplift, the Leadville Limestone is partly drained by Rifle Creek; during lowflow conditions, most of the flow of the creek is water from 

the Leadville. The water in Rifle Creek flows over Rifle Falls 

in a spectacular display.

PENNSYLVANIAN

The Pennsylvanian was a time of change from a shallow 

water, marine deposition in earlier Paleozoic to deposition 

in small basins. Thick sequences of marine limestone and 

shale in the lower part of the Pennsylvanian were succeeded by evaporitic and coarse-grained clastic rocks in the upper part. The Uncompahgre uplift, south of Grand Junction, 

was a source area for the clastic rocks. One small basin just 

east of the Piceance structural basin contains more than 

10,000 feet of Pennsylvanian rock.

Sandstone formations of Pennsylvanian age and those of 

the overlying Permian sequence may constitute an aquifer 

system. A program of drilling, aquifer testing, and sampling 

is needed to appraise the potential of these sandstone 

formations.

PERMIAN

Rocks of the Permian Period underlie most of the northern two-thirds of the basin. The total thickness of the Permian rocks probably does not exceed 500 feet. Permian 

formations were deposited in shallow seas (Park City Formation) and on adjacent lowlands (Weber Sandstone, upper part, and Maroon Formation, upper part).

The Weber Sandstone is fractured, porous, and probably 

permeable. Exploratory oil tests using holes drilled near 

Meeker, Colo., yielded warm, salty water from the Weber 

Sandstone. Other sandstone formations of Permian age may 

be aquifers.

TRIASSIC

Triassic rocks were deposited in three different environments. The Moenkopi Formation at the base is a nearshore marine deposit, the overlying Chinle Formation is a 

continental deposit, and the Glen Canyon Group (partly

^S\ fdr

The Leadville Limestone of Mississippian age, which may be an 

aquifer (fig. 66).

Jurassic) includes two units deposited by wind and separated 

by stream deposits. Triassic rocks are as thick as 1,500 feet 

at the northern edge of the basin. The Uncompahgre uplift, 

south of Grand Junction, was a source area for much of the 

Triassic sediment.

The Chinle and Glen Canyon form a thick sequence that 

is mostly sandstone. These formations are aquifers in Utah 

and other regions, but have not been tested for their aquifer 

potential in the Piceance basin.

JURASSIC

Jurassic rocks underlie the entire basin. The marine units 

in the lower part of the Jurassic thicken westward to possibly more than 300 feet. In the upper part of the Jurassic, 

the Morrison Formation of continental origin is more than 

600 feet thick at its western limit in the structural basin.
102 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Weber Sandstone of Permian age (fig. 67).

Oil production from the Entrada Sandstone in northwestern Colorado indicates that these rocks are permeable 

in northwestern Colorado. At Rangely, water produced 

from the Entrada was injected into the Weber Sandstone for 

secondary recovery of crude oil.

The Morrison Formation of Jurassic age yields oil and gas 

in many oil fields of northwestern Colorado; the formation 

is typically fractured and is known to be an aquifer in other 

regions.

CRETACEOUS

Cretaceous rocks underlie the entire basin. The Burro Canyon Formation and Dakota Sandstone at the base are 

relatively thin in comparison to the Upper Cretaceous rocks

109° WYOMING

TRIASSIC 

From MacLachlan, 1972

108o WYOMING 1D7o_______106° 

"T'COLORADO 1 r

JURASSIC 

From McKee and others, 1956

that are more than 10,000 feet thick. Cretaceous rocks are 

mostly clastic rocks of marine (Mancos Shale) and continental to marine (Burro Canyon Formation and Mesaverde 

Group) origin. The Dakota may have been deposited in 

coastal swamp and beach areas.
PALEOZOIC AND MESOZOIC FORMATIONS AS GROUND-WATER RESERVOIRS 103

WYOMING irno

CRETACEOUS

From McGookey and others, 1972

60 MILES

) 60 KILOMETERS

EXPLANATION

AREA WHERE ROCKS OF 

SYSTEM ARE PRESENT

PICEANCE STRUCTURAL 

BASIN

ZERO THICKNESS LINEDashed where approximately located

DIRECTION OF THICKENING

Distribution of Mesozoic rocks under 

the Piceance structural basin (fig. 68 above and facing page).

Several formations of Cretaceous age are aquifers. Wells 

yielding water and gas have been completed in the Dakota 

Sandstone over a large region. Near Douglas Creek, to the 

west of the Piceance basin, upper sandstone members of the 

Mancos Shale yield water to wells. Water also is reported 

in the Mancos Shale in nearby regions. The sandstones of 

the Mesaverde Group in a coal mine near Meeker are fractured and water bearing. The mine must be pumped continuously to prevent flooding. In general, many sandstones of 

the Mesaverde Group are locally porous and water bearing. In the Piceance basin, these sandstones may be sufficiently porous and permeable for wastewater injection.

Morrison Formation

Entrada Sandstone

The Morrison Formation (A) and Entrada Sandstone (6) of Jurassic 

age, which may be aquifers (fig. 69).

TEST HOLES ARE NEEDED TO EXPLORE 

FOR DEEP AQUIFERS

Many formations of Paleozoic and Mesozoic age are fractured, porous, permeable, and capable of yielding appreciable amounts of ground water for oil-shale development. 

A test hole could be drilled in the Piceance basin through 

all formations that may be aquifers. A good place for such 

an exploratory hole is near the White River uplift on the 

east side of the Piceance basin, where only a few thousand 

feet of drilling would penetrate the entire sedimentary sequence and reach rocks of Precambrian age. A comparable 

test hole near the center of the Piceance basin might be 

25,000 feet deep and would be prohibitively expensive.
104 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

___ .*r

Mesaverde Group

The Dakota Sandstone, Mancos Shale, and Mesaverde Croup of Cretaceous age, which may

be aquifers (fig. 70).
WEST

EAST RIM OF 

UINTA BASIN

PALEOZOIC AND MESOZOIC FORMATIONS AS GROUND-WATER RESERVOIRS

PICEANCE BASIN

105

EAST

WHITE RIVER UPLIFT

Diagrammatic east-west cross section, northwestern Colorado, showing distribution of rocks for systems of Paleozoic and Mesozoic

Era (fig. 71).

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Bass, N. W., and Northrup, S. A., 1963, Geology of Glenwood Springs

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Cashion, W. B., compiler, 1973, Geologic and structure map of the Grand

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Hansen, W. R., and Carrara, P. E., 1980, Geologic map of the Tanks Peak 

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Johnson, R. C., and May, Fred, 1980, A study of the Cretaceous-Tertiary 

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1482-B, 27 p.

Johnson, R. C., May, Fred, Hansley, P. L., Pitman, J. K., and Fouch, T. D., 

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section of the Upper Cretaceous Mesaverde Group in Hunter Canyon, 

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Chart OC-91.

King, P. B., and Beikman, H. M., compilers, 1974, Geologic map of the 

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the Rocky Mountain region, Rocky Mountain Association of Geologists: 

Denver, A. B. Hirschfeld Press, p. 60-75.

Lohman, S. W., 1965, Geology and artesian water supply. Grand Junction area, Colorado: U.S. Geological Survey Professional Paper 451, 

149 p.

McGookey, D. P., Haun, J. D., Hale, L. A., Goodell, H. G., McCubbin, 

D. G., Weimer, R. J., and Wulf, G. R., 1972, Cretaceous System, in 

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McKee, E. D., and others, 1967, Paleotectonic investigations of the Permian System: U.S. Geological Survey Miscellaneous Geologic Investigations Map 1-450.
106 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

____1956, Paleotectonic maps of the Jurassic System: U.S. Geological 

Survey Miscellaneous Geologic Investigations Map 1-175.

MacLachlan, M. E., 1972, Triassic System, in Geologic atlas of the Rocky 

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A. B. Hirschfeld Press, p. 166-176.

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p. 111-128.

Murray, F. N., 1966, Stratigraphy and structural geology of the Grand 

Hogback Monocline, Colorado: Boulder, University of Colorado, Ph. D. 

thesis, 219 p.

Pipiringos, G. N., and Imlay, R. W., 1978, Lithology and subdivisions of the Jurassic Stump Formation in southwestern Idaho and 

adjoining areas: U.S. Geological Survey Professional Paper 1035-C, 

256 p.

Pipiringos, G. N., and Rosenlund, G. C., 1977, Geologic map of the White 

Rock quadrangle, Colorado: U.S. Geological Survey Miscellaneous Field 

Studies Map MF-837.

Poole, F. G., and Stewart, J. H., 1964, Chinle Formation and Glen Canyon 

Sandstone in northeastern Utah and northwestern Colorado: U.S. 

Geological Survey Professional Paper 501-D, p. 30-39.

Ross, R. J., Jr., and Tweto, Ogden, 1980, Lower Paleozoic sediments and 

tectonics in Colorado: Rocky Mountain Association of Geologists 1980 

Symposium, Colorado Geology, p. 47-56.

Rowley, P. D., and Hansen, W. R., 1979, Geologic map of the Plug Hat 

Rock quadrangle, Moffat County, Colorado: U.S. Geological Survey 

Geologic Quadrangle Map GQ-1514.

Rowley, P. D., Dyni, J. R., Hansen, W. R., and Pipiringos, G. N., 1979, 

Geologic map of the Indian Water quadrangle, Moffat County, Colorado: 

U.S. Geological Survey Geologic Quadrangle Map GQ-1516.

Tweto, Ogden, 1975, Laramide (Late Cretaceous-early Tertiary) orogeny 

in the southern Rocky Mountains: Geological Society of America Memoir 

144, p. 1-44.

Tweto, Ogden, compiler, 1976, Geologic map of the Craig 1°X2° quadrangle, northwestern Colorado: U.S. Geological Survey Miscellaneous 

Investigations Map 1-972.

Tweto, Ogden, Moench, R. H., and Reed, J. C., Jr., 1978, Geologic map 

of the Leadville 1°X2° quadrangle, northeastern Colorado: U.S. Geological Survey Miscellaneous Investigations Map 1-999.

Spoil piles of retorted shale are the subject of special 

studies, as described in the following chapter.
CHEMICAL EFFECTS AND CONTROL OF LEACHATES 

FROM OIL-SHALE SPOIL PILES

By KENNETH G. STOLLENWERK

TOXIC SUBSTANCES MAY BE LEACHED 

FROM SPOIL PILES OF RETORTED OIL SHALE

Spoil piles resulting from aboveground disposal of 

retorted oil shale and associated wastes could cause contamination of ground water and surface water in the Piceance basin. Studies have shown that large quantities of 

substances that are potentially toxic to plants and animals, 

including humans, may be released to the water that comes 

in contact with retorted oil shale. One such study shows the 

results of leaching oil shale that was retorted using two different aboveground processes. Leachate from a sample of 

recently mined unretorted oil shale was also included in the 

study for comparison, because significant quantities of 

crushed unretorted oil shale also may be stored in piles on 

the land surface.

Dissolved solids, molybdenum, fluoride, and boron are 

the major inorganic contaminants in leachate from oil shale. 

High concentrations of dissolved solids interfere with the 

normal biologic functions of plants and animals. Small 

quantities of molybdenum, fluoride, and boron are essential for plants and animals; however, larger quantities can 

be toxic. Leachate from oil shale that has been retorted using various processes, as well as leachate from unretorted 

oil shale, would have to be substantially diluted in order 

to meet the recommended criteria of the U.S. Environmental Protection Agency for potable water and for irrigation 

water. The limits for the National Pollutant Discharge 

Elimination System (NPDES) specify the maximum allowable daily discharge for a contaminant from any single 

source. Any leachate or treated leachate that is discharged 

to streams will have to meet NPDES standards. Several factors affect the type and quantity of constituents leached from 

retorted oil shale the chemical and mineralogical composition of the unretorted shale and of the retorted shale waste, 

the particle-size distribution of the fresh and retorted oil 

shale, the type of retorting process used, and the conditions 

under which leaching occurs. In addition, several other 

waste products, such as industrial wastewater and other 

solid-waste material, may be disposed with the retorted oil 

shale, and these other products may modify the composition of the leachate.

The aboveground disposal of retorted oil shale and 

associated wastes is described in the chapter "Development 

of the oil shale and associated minerals."

LEACHATE FROM SPOIL PILES MAY FLOW 

INTO AQUIFERS AND STREAMS

The impact of leachate from spoil piles on the quality of 

ground and surface water in the Piceance basin ultimately will 

depend upon the quantity of leachate produced and location 

of spoil piles. Natural recharge to the bedrock aquifers results 

from snowmelt at the higher altitudes in the basin. Placement 

of spoil piles in a recharge area also could permit recharge 

on the spoil piles themselves. The resulting leachate draining 

from the spoil piles may migrate into natural flow systems 

in the soil, alluvium, and bedrock, where some of the potentially toxic elements may be removed. As the leachate migrates, it will be subject to chemical and physical reactions 

such as dispersion, diffusion, filtration, ion-exchange reactions, absorption, chemical precipitation, and biochemical 

degradation, which may change its quality. Eventually the 

leachate could become part of the regional flow system and 

might discharge to springs and streams. Placement of spoil 

piles in areas of natural discharge is undesirable also because 

water discharging from springs could saturate the sides and 

bottom of spoil piles, causing leaching and instability.

The quality of surface and ground water can be impacted 

by surface runoff over or through spoil piles. To minimize 

or prevent this, diversion channels can be constructed to 

direct surface runoff around the spoil piles. The diversion 

system will have to be maintained to prevent reestablishment 

of natural drainage patterns.

Sources of contaminants other than leachates also could 

lead to a deterioration in the quality of ground and surface 

water. Wastewater from the retorting process could leak 

through the sides and bottoms of holding ponds before it is 

treated. Dams will be constructed downstream from the spoil 

piles in order to collect surface runoff from the piles, and 

other ponds may be constructed to store water pumped during mine drainage. Infiltration of water from these retention 

ponds could be a source of contamination.

107
108 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

EXPLANATION

UNRETORTED OIL SHALE

RETORTED OIL SHALE USING 

PARAHO PROCESS

RETORTED OIL SHALE USING 

TOSCO II PROCESS

IRRIGATION WATER

MUNICIPAL WATER 

SUPPLY

Water quality criteria 

recommended by 

U.S. Environmental 

Protection Agency

60,000

50,000 -

40,000 -

30,000

Q 20,000

10,000

Note: NPDES standards require a

 maximum daily -discharge lim *i

of less than 1 ton per day of

dissolved solids and no more

_

_

'

than J.U milligrams per liter of

fluoride, or 3.5 milligrams per liter of

boron in wastewater from any

single source discharging to

a stream

?

T ^

j

c

o

(5

O

o

DISSOLVED SOLIDS MOLYBDENUM

c

0

c

o 

o

z

FLUORIDE

"^~r1 

BORON

Oi)

30 z

O 

<r

O

CO

LU

25 |

O

D tr

_l LU 

LL. ( 

20 =>£

Z D_

CQ ^

^ o: O o

15 ^^

ol

z o z10 <

LU

0

z

o

5 u

0

Concentrations of dissolved solids, molybdenum, fluoride, and boron in leachate from three different types of oil shale

(fig. 72).

CONTROL TECHNOLOGY CAN REDUCE 

CONTAMINATION FROM SPOIL PILES

Several procedures can minimize the adverse effects of the 

contaminants from spoil piles:

1. Locate spoil piles in small watersheds that have little 

precipitation, in order to minimize the quantity of 

leachate generated.

2. Select a site that is distant from springs so that discharge from springs will not saturate the bottom and 

sides of the spoil piles.

3. Grade the spoil-pile surfaces to minimize ponding and 

infiltration.

4. Establish a vegetative cover on the surface of the spoil 

piles to transpire some of the water that infiltrates the 

surface.

5. Induce controlled leaching of the spoil piles in order 

to decrease the concentration of dissolved solids in any 

future leachate. The induced leachate would have to 

be stored, treated, and disposed properly.

6. Install liners beneath wastewater-holding ponds in 

order to induce or prevent infiltration.
EXPLANATION

UNPOLLUTED WATER

WATER CONTAINING POTENTIALLY 

TOXIC SUBSTANCES

DIRECTION OF GROUND-WATER 

FLOW

Impounded runoff and 

discharge from oilshale processing plant

/

EVAPOTRANSPIRATION

PRECIPITATION

EVAPOTRANSPIRATION

Bedrock Saturated zone

8P 

o n

Possible movement of toxic substances leaching from oil-shale spoil piles (fig. 73).
110 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Mitigation measures may prevent significant quantities of 

leachate from moving into the ground- and surface-water 

systems during the lifetime of a retorting operation. However, leachate may continue to infiltrate the land surface for 

hundreds of years before contaminants are reduced to levels 

harmless to plants and animals.

REFERENCES

Bates, E. R., and Thoem, T. L., 1979, Pollution control guidance for oil 

shale development: .U.S. Environmental Protection Agency, Revised draft 

report, p. 370.

Stollenwerk, K. G., and Runnells, D. D., 1981, Composition of leachate 

from surface-retorted and unretorted oil shale:. Environmental Science 

and Technology, American Chemical Society, v. 15, no. 11, p. 

1340-1346.

U.S. Environmental Protection Agency, 1976, Quality criteria for water: 

U.S. Environmental Protection Agency, Washington, D.C., 256 p.

In situ retorts also may affect water quality, as the following discussion indicates.
CHEMICAL EFFECTS AND CONTROL OF WASTES 

FROM IN SITU RETORTS

By JERRY A. LEENHEER

WATER FROM IN SITU RETORTS 

MAY AFFECT WATER QUALITY

Although more retorted shale is commonly stored on the 

land surface from aboveground than from in situ processes, 

the treatment and disposal of solid, liquid, and gaseous 

wastes can be controlled better using aboveground processes. Wastes produced by in situ processes cannot be controlled as easily because they remain underground where 

they are mostly inaccessible. The processing of oil shale 

using in situ retorts is discussed in the chapter "Development of the oil shale and associated minerals."

WASTES PRODUCED BY MODIFIED IN SITU 

RETORTS ARE NOT COMPLETELY KNOWN

Modified in situ retorts are planned on tract C-b in the 

Piceance basin in part because of concerns with resource 

recovery, costs of mining, and disposal of retorted shale. 

With the modified in situ process, about 20 to 40 percent 

of the oil-shale ore is processed and disposed at the land surface; the remainder is left underground for in situ extraction of shale oil. Little is known about the quantities and 

properties of, and ultimately, the wastes produced by in situ 

retorting of oil shale. Therefore, considerable research is being performed to determine how wastes are produced during the construction, during the burning, and after the 

abandonment of in situ retorts, and to document the effects 

of wastes on water quality.

Potential sources of wastewater include:

1. Retort water generated during oil-shale retorting,

2. Water produced during mine drainage,

3. Leachate from unretorted and from processed oil shale,

4. Wastewater from air emission-control systems,

5. Cooling water,

6. Water flushed from boilers,

7. Sanitary wastewater.

The amounts of water from each source change during retort 

construction, oil-shale processing, and after retorts are 

abandoned.

The two most important wastewater sources are minedrainage water, which constitutes the largest volume of 

wastewater, and retort water, which may contain the largest 

amounts of dissolved solids and potential contaminants. 

Most of the mine-drainage water ultimately may be used as 

the water supply for aboveground retorts, shale-oil upgrading 

facilities, and moistening of retorted shale. Initially, minedrainage water will be disposed of by injection underground, 

application to the land surface, or discharge into surface 

streams. Retort water is a by-product of the combustion of 

hydrocarbons, the dehydration of oil-shale minerals by in 

situ processes, and the flow of ground water into retorts. 

Most retort water is produced as an emulsion in shale oil 

and must be physically separated from the oil. A smaller 

amount of water condenses from retort vapors. Only 5 to 

20 percent of the liquid product of an aboveground retort 

is retort water, but approximately equivalent volumes of 

retort water and shale oil are produced from in situ retorts.

Retort waters have high concentrations of ammonia that 

can be recovered during water treatment and used to manufacture fertilizers. Retort waters also have high concentrations 

of sulfur and organic compounds, which can be detrimental 

to the environment. Although smaller volumes of aboveground retort waters are produced compared to in situ retort 

waters, the dissolved-solids concentration is higher in aboveground retort waters. Therefore the total volume of dissolved solids released by both types of retorting is about equal.

SOURCES AND TYPES OF WASTEWATER 

DEPEND ON THE STAGE OF 

MODIFIED IN SITU RETORTING

The sources and volumes of wastewater from the modified 

in situ retorts change as construction and retorting proceed. 

During construction of the retort, most of the wastewater 

is mine drainage. Mine water may become more oxidizing 

during ponding, and treatment may be required prior to injection or disposal to streams. Leaching of contaminants by 

rainfall and snowmelt percolating through the unretorted 

shale in storage piles also may contribute a minor amount 

of wastewater.

Ill
to

/""""Yj ^~ ^y~^ Injected water needs

( ' '"S ^1 J ^-5 to be chemically

Mined oil shale will *J@ ^ __ £f£ Mine , wgter gTun^watef" processed in above- cL ^PRECIPITATION J3 nnPlant become more oxidizing grouna water Q 

ground retorts -- - \\\\ ^ during ponding ^ p Injection ^

ac ivi IBS may treatment Waste shale £ reduce streamflow "edimeiu ^.-tor >-«^S3- -v olant water XSSTJwTx -- ^ T" /,

Q Discharge ___ ^^^u &// /^^ \ .x^^ T" Min0

r| to stream T^TSLLL - // 4$^ t^^p^^-^" drainaae

^~^~3^>v.. ^j.,,, .. , L ,-J 1 ~-^^ J I I pump

^-^ Valley-fill Leachate from

alluvium shale pile - % - Oil shale 

In situ retort

under construction

. Jponnr '

1 __ Saturated zone - -

\

^j £_ i

a __ n ] ' ^~- ^^ 

j^^U | Pond ^^

V-^_^ <^^

Dewatered zone W?:

F

, 

'*'

Mine ^ tef table "^ >f 

Shaft ^

: Injected water

stored in bedrock

f aquifer

// ~*

$ s

J^__vvell___

~ - .

^

- ^~

; // ^ x

' Part of the injected water also

. * may migrate into streams or into

\v ' "" " '" " ;/ f reiuri iune irorn wniun u wdb

 muni _»- drained

Oil shale

w

5

5

1 3ya 

%m 

COQc

§CO

is

1s

2

t

P d

n

1

hit

Not to scale About 20 to 40 percent of the oil shale £

must be mined in order to provide working &2

space to construct a retort Z

nOrr

Mine drainaee. water reiniertion. and wastewater disnosal during in situ retort construction (fis. 74). P
CHEMICAL EFFECTS AND CONTROL OF WASTES FROM IN SITU RETORTS 113

( Demisting 

tank

Shale oil to treatment «= ^ 

Process retort water to disposal -<: -1

Shale oil and process 

retort water emulsion

/-! o <'boC> 0 ^<=> <3O6., "~~"r QfcteXge <P0sl Qc&&?i&<>&2

'a 'C| i»»g-^* o » o » « V ' ><"

*Mine drainage needs to 

be continued during the 

retorting in order to prevent ground water from 

entering retort

Active modified in situ retort (fig. 75).
114 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

EXPLANATION

i GROUND-WATER MOVEMENT

Land surface

Bulkhead sealx

In situ retort after abandonment (fig. 76).
CHEMICAL EFFECTS AND CONTROL OF WASTES FROM IN SITU RETORTS 115

Retort water is produced during operation of the in situ 

retort. Retort water recovered with the shale oil and gas 

probably will need extensive treatment before disposal or 

reuse, but some retort water, gases, and shale oil may 

migrate through small fractures. The effect of these 

unrecovered liquid and gaseous wastes on the ground-water 

quality has not been determined.

When the burned modified in situ retorts are abandoned 

and mine-drainage operations cease, the retort will flood 

with ground water as it cools. As the regional ground-water 

flow is reestablished, the retorted shale will be leached by 

ground water. The physical stability of the saturated shale 

and the fate of solutes leached from the shale are two concerns about abandonment of modified in situ retorts.

CONTROL TECHNOLOGY CAN DECREASE 

CONTAMINATION FROM IN SITU RETORTS

Technology will be important to control leachate from 

in situ retorts. Hundreds of in situ retorts could contaminate 

ground and surface water basin wide for hundreds of years. 

Several techniques have been proposed to minimize the 

adverse effects of any contaminants from in situ retorts:

1. Maintain operating pressures in the active in situ retorts in the unsaturated zone at less than surrounding

air pressures, using controlled mine ventilation. The 

lower pressure should help to contain gaseous and liquid wastes within the retort.

2. Inject grout into the retort zone before retort abandonment in order to prevent the infiltration of and 

leaching by ground water.

3. Treat wastewater before discharging it into streams.

4. Store piles of mined, unretorted oil shale in areas 

where problems of erosion and leaching are less likely to develop.

REFERENCES

Jackson, L. P., Poulson, R. E., Spedding, T. ]., Phillips, T. E., and Jensen, 

H. B., 1975, Characteristics and possible roles of various waters significant to in situ oil shale processing:. Proceedings of the Environmental 

Oil Shale Symposium, Quarterly of the Colorado School of Mines, v. 

70, no. 4, p. 105-134.

Stuber, H. A., and Leenheer, J. A., 1978, Fractionation of organic 

solutes in oil shale retort waters for sorption studies on spent shale:. 

Division of Fuel Chemistry, American Chemical Society, v. 23, no. 2, 

p. 165-174.

Gaseous and particulate emissions from oil-shale retorts 

to the atmosphere may change the quality of precipitation 

and lake water, as the following section indicates.

EFFECTS OF EMISSIONS FROM OIL-SHALE RETORTS

TO THE ATMOSPHERE

By JOHN T. TURK

Aboveground retorts produce emissions that discharge to 

the atmosphere and may alter the chemical characteristics 

of precipitation. In the Northeast, acid rain has resulted 

partlly from similar emissions from coal-burning powerplants. The altered precipitation may affect the water quality in lakes, impair the aquatic environment, and increase 

the general corrosiveness of water suppies in the drainage 

basin.

OIL-SHALE RETORTING EMITS 

CONTAMINANTS TO THE ATMOSPHERE

The retorting of oil shale releases gases and particles from 

the retorted material to the atmosphere. The components 

released include water and the products of oxidation or 

reduction reactions at high temperatures, such as:

1. Low molecular weight organic compounds;

2. Volatile elements, such as mercury and arsenic;

3. Ammonia; and

4. Oxides of nitrogen and sulfur.

The amounts of many components that may be released 

are difficult to predict; however, permissible emission concentrations for sulfur dioxide and the nitrogen oxides have 

been established by the U.S. Environmental Protection 

Agency for one commercial operation. If the emissions currently allowed for an oil-shale retort that produces 47,000 

barrels of shale oil per day are extrapolated for greater production, oil-shale retorting could become a major source of 

acidic gases such as sulfur dioxide and nitrogen oxides. The 

projected emission concentrations for oil-shale retorting are 

compared with those concentrations produced by modern 

800-megawatt coal-burning powerplants of the type operated at Craig, Colo.

THE REGIONAL QUALITY OF 

PRECIPITATION CAN BE MONITORED

Emissions to the atmosphere from oil-shale retorts may 

produce changes in the chemistry of snow and rain downwind from the sources of the emissions. To document the 

geographical extent as well as the magnitude of chemical

alteration, the quality of precipitation upwind and downwind from the potential sources of emissions can be 

monitored. The monitoring is needed for three main reasons:

1. To detect changes,

2. To verify the effectiveness of controls, and

3. To allow early intervention if a hazardous situation 

develops.

160

140

120

100

80

60

40

20

0 0.2 0.4 0.6 0.8 1 

SHALE-OIL PRODUCTION, IN MILLIONS OF BARRELS PER DAY

Comparison of projected emissions from oil-shale retorting to 

measured emissions from coal-fired powerplants in northwest 

Colorado (fig. 77).

117
118 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

To separate the effects of oil-shale development from 

those of other sources of emissions (for example, coalburning powerplants), many monitoring stations will be 

needed. The predominant wind directions near the site of 

oil-shale development and near existing coal-burning 

powerplants in the region are known. Monitoring stations 

should be located not only on the margins of the region of 

concern, but also between sources that may interact to affect precipitation quality. Areas that may be affected, such 

as the Flat Tops and Mount Zirkel Wilderness Areas, also 

should be monitored.

CHEMICAL CHANGES IN PRECIPITATION 

MAY ACIDIFY SOME LAKES

Atmospheric emissions are carried by winds and deposited 

by precipitation and dry fallout on a variety of downwind 

watersheds. Acidity is produced by the reaction of sulfur 

dioxide, nitrogen oxides, and water in the atmosphere. The 

greatest effect of acidic deposition is likely to be in watersheds where the bedrock and soil are relatively unreactive 

and, thus, unable to neutralize the acidity. The ability of 

a hydrologic system to neutralize acidity depends on its

MAP 

AREA ,DENVER1

COLORADO

Wind rose lines radiate toward 

direction from which wind 

blows. Line length is 

proportional to wind strength

109° 108°

MOUNT ZIRKEL 

WILDERNESS

Typical winter 

wind rose at 

Craig, Cole

[Typical winter 

| wind rose at 

I tract C-a

25 75 MILES

 I 

75 KILOMETERS

Predominant wind directions in northwestern Colorado (fig. 78).
EFFECTS OF EMMISSIONS FROM OIL-SHALE RETORTS 119

alkalinity and can be determined from a plot of pH versus 

the amount of a standard acid added to a given volume of 

water.

For example, the abilities of two lakes in the Flat Tops 

Wilderness Area (Island and Marvine Lakes) to neutralize 

added acid are different. Although water from lower Marvine Lake maintains a pH greater than 5.5 for a relatively 

large addition of acid, the pH of water from the upper Island 

Lake decreases rapidly with only small additions of acid. 

The shape of the titration curve for upper Island Lake approximates the titration of pure water containing no 

alkalinity.

A network to monitor changes in lake chemistry and in 

biology caused by acidification of the lake needs to include 

primarily lakes with low alkalinity (for example, upper 

Island Lake). This lake and similar lakes with low alkalinity will be affected long before the more alkaline lakes of 

an area. At pH values lower than about 5.5, fish will be 

harmed to some extent. At pH values lower than about 4.5, 

most fish are unable to survive. Titration curves such as 

these are good relative measures of the overall chemical and 

biological sensitivity of lake systems to acidification.

LAKES SENSITIVE TO ACIDIFICATION 

MAY HAVE COMMON CHARACTERISTICS

Lakes that are most likely to be affected by acidification 

(that is, the least alkaline lakes) have some common 

characteristics. For example, the relation between alkalinity and altitude for 15 lakes of the Flat Tops Wilderness Area 

shows that the most sensitive lakes are located at the highest 

altitudes. Altitude determines many basin characteristics in 

the vicinity of potential oil-shale development. Bedrock 

type, amount of tree cover, snowpack accumulation, precipitation volume, and timing of snowmelt are examples.

Many of these watershed characteristics are related to 

altitude in such a way as to maximize contaminant loading 

to the lakes that are least capable of neutralizing acidity 

the high-altitude lakes. The least reactive bedrock types, the 

greatest rate of runoff per unit area of watershed, and the 

greatest deposition of precipitation and contaminants are 

associated with the highest altitudes. Thus, the high-altitude 

lakes are even more susceptible to the effects of acidification than their low alkalinity values would indicate.

^ Theoretical dilution curve, pure water

 Top layer of upper Island Lake

A Top layer of lower Marvine Lake

345 

ACID ADDED TO SAMPLE, IN MILLILITERS

Titration curves that indicate the effects of adding acid to pure water and to water samples from 

lower Marvine Lake and upper Island Lake (fig. 79).
to

O

n

m

1

Z

8

Upper Island Lake (very susceptible to acidification) is located in the eastern part of the Flat Tops Wilderness Area (fig. 80).
EFFECTS OF EMMISSIONS FROM OIL-SHALE RETORTS 121

80

70

60

CO

<

cc 

U

d 50

40

y 30

U

CO

>-

I 20

_i

<

^

_i

<

10

0

9300 9700 10,100 10.500 10,900 

ALTITUDE, IN FEET ABOVE SEA LEVEL

11,300

Sensitivity of lakes to acidification is a function of altitude (fig. 81).

SIMULATION MODELS CAN BE USED 

TO STUDY THE EFFECTS OF EMISSIONS 

ON THE ATMOSPHERE, PRECIPITATION, 

AND LAKES

Results of studies of lakes in the Rat Tops Wilderness Area 

indicate that many lakes have little ability to neutralize 

added acidity. Even small additions of acid to these lakes 

will decrease their pH. The effects of incremental increases 

of emissions on these very sensitive lakes can be predicted 

using models that simulate acid deposition on the lake watersheds. The complex terrain of sensitive areas, such as the 

Flat Tops and Mount Zirkel Wilderness Areas, necessitates 

the development of atmospheric-transport and deposition

models. Such models calculate the dispersion of emissions 

and the reactions that produce acidic components as functions of the location and sources of emissions.

The models also would calculate the average deposition 

rates of the acidic products on sensitive watersheds. 

Combined with data already available on the alkalinity of 

lakes in the watersheds, the effect on pH and fish can be 

approximated.

Even in the absence of emissions, natural processes result 

in a range of pH in sensitive lakes. As acid is added, 

however, the pH in all sensitive lakes will decrease. A basis 

for establishing standards for concentrations of constituents 

in emissions can be developed by calculating the concentrations that would cause the pH in some specified percentage of the lakes to decrease to values harmful to fish. These 

standards could reduce the cost of scrubbing equipment for 

retorts by requiring no more control than that necessary to 

prevent harm to most sensitive lakes.

EMISSIONS OF SULFUR DIOXIDE AND NITROGEN OXIDES

Simulation models to quantify the range in lake acidity as a function of emissions (fig. 82).
122 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

CONTROL TECHNOLOGY WILL REDUCE 2

THE EFFECTS OF EMISSIONS FROM RETORTS

Several procedures have been proposed to reduce the effects of emissions from retorts on hydrologic systems:

1. Scrubbing equipment can be installed on aboveground 

retorts to reduce the emissions to an acceptable level.

Affected lakes can be treated chemically to reduce the 

acidity of the lake water.

Affected watersheds can be treated chemically to 

reduce the acidity of water supplies over a large region.

The relative benefits, requirements, and effects of different 

levels of oil-shale development are analyzed in the final 

chapter.
LEVELS OF MINERAL DEVELOPMENT

BENEFITS, REQUIREMENTS, AND EFFECTS OF DIFFERENT LEVELS

OF OIL-SHALE DEVELOPMENT

By O. JAMES TAYLOR

The development of oil-shale reserves will have several 

consequences. Production of shale oil can reduce or 

eliminate the dependence'of our Nation on imported sources 

of crude oil. However, development will require new water 

supplies and will affect allocation of regional water 

resources.

Consequences of developing the minerals nahcolite and 

dawsonite associated with the oil shale are not considered 

in detail in this chapter, but they can be estimated. Certainly 

multimineral leasing and development will allow more 

efficient production of the associated minerals during mining activities principally devoted to oil-shale development. 

The required expanded development would result in increased volumes of waste for disposal in spoil piles. This 

additional waste also would contain leachable substances. 

Industrial water requirements would increase because of the 

expanded mining and development activity. However, the 

resulting increase in mineral production would be substantial and the economic efficiency could be high compared to 

the development of the associated minerals separate from 

the oil shale.

THREE LEVELS OF DEVELOPMENT FROM 

OIL SHALE ARE CONSIDERED

Oil production from shale will have effects on National 

crude-oil supplies and on water resources in the Piceance 

basin, and will have other impacts on the region. The effects are assessed for three levels of development: Level A 

presumes a small production, 200,000 barrels per day; level 

B presumes a moderate production, 2 million barrels per 

day; and level C presumes an intense development, 6 million 

barrels per day.

Oil developmment from shale could reduce the need for 

other sources of domestic and imported crude oil. In 1980, 

average domestic crude-oil production was 8.6 million barrels per day; an additional 5.16 million barrels per day was 

imported. As the chart shows, with intense development, 

shale oil could replace most of the domestic crude oil or all 

of the imported crude oil, assuming 1980 usage. Small or 

moderate levels of development would have proportionately 

smaller effects.

THE LEVEL OF PRODUCTION FROM OIL 

SHALE WILL AFFECT NATIONAL SOURCES 

OF OIL, THE FLOW OF DOLLARS OVERSEAS, 

AND DURATION OF OIL-SHALE RESERVES

Possible changes in the amount of oil from different sources 

consumed in the United States were considered assuming that:

1. The National consumption rate will be constant, and

2. Shale oil will replace imported crude-oil supplies before 

production of domestic crude-oil is reduced.

The level-A development plan has little effect on crudeoil imports; the level-B development plan reduces required 

imports but does not affect domestic production of crude 

oil; the level-C development plan eliminates the need for 

imported crude oil and decreases the required production 

of domestic crude oil.

During 1980, about $64 billion was spent on imported 

crude oil. The progressive increase in oil production from 

shale would allow corresponding decreases in expenditures 

for imported oil. The impact of oil-shale production on the 

flow of dollars overseas was estimated by deducting the 1980 

price, $33.97 per barrel, for each barrel of shale oil that 

would be produced. Intense development would eliminate 

all requirements for imported crude oil. Greater production 

of oil from shale could reduce the use of domestic crude oil, 

or the surplus could be exported.

NOT ALL OF THE SHALE-OIL RESOURCE 

CAN BE RECOVERED, BUT THE RESERVES 

ARE LARGE ENOUGH TO SUPPLY OUR 

NATION WITH OIL FOR MANY YEARS

Although the resource of shale oil in the Piceance basin 

totals 1.2 trillion barrels, only part of it can be recovered. 

The total amount that can be recovered depends on the accessibility of the oil shale for development, the method of 

mining used, and the retorting technique used. Improvements in mining and retorting technology probably will increase recovery, but effects of future improvements are 

difficult to predict.

125
to

OIL-SHALE

DEVELOPMENT

LEVELS

PRESUMED RATE 

OF PRODUCTION

FROM 

OIL SHALE

SHALE-OIL PRODUCTION

COMPARED TO

DOMESTIC CRUDE OIL FOR

1980 (8,600,000 BARRELS

PER DAY)

SHALE-OIL PRODUCTION

COMPARED TO

IMPORTED CRUDE OIL FOR

1980 (5,160,000 BARRELS

PER DAY)

POSSIBLE CHANGES IN 

NATIONAL SOURCES

OF OIL

ASSUMING 1980 

USAGE RATES

FLOW OF 

DOLLARS 

OVERSEAS, 

ASSUMING AVERAGE CRUDE

OIL PRICE

FOR 1980($33.97

PER BARREL)

DURATION

OF OIL 

RESERVES IN 

SHALE, ASSUMING TOTAL 

RECOVERY OF 

500 BILLION 

BARRELS

LEVEL A

SMALL

DEVELOPMENT

200,000

BARRELS PER

DAY

61.5 BILLION

DOLLARS PER

YEAR

6,850 YEARS

36% 62%

LEVEL B

MODERATE

DEVELOPMENT

2 MILLION

BARRELS PER

DAY

Domestic

crude

oil

Imported

crude

Shale oil 

oil

23%

39 BILLION

DOLLARS PER

YEAR

685 YEARS

15% 62%

LEVEL C

INTENSE

DEVELOPMENT

6 MILLION

BARRELS PER

DAY

Domestic

Shale Imported 

oil crude

ZERO 230 YEARS

44% 0% 56%

Effects of different levels of oil development from shale on National oil supplies (fig. 83).
BENEFITS, REQUIREMENTS, AND EFFECTS OF DIFFERENT LEVELS OF DEVELOPMENT 127

The accessibility of the oil shale is limited by several factors. A developer must acquire the proper lease or mining 

claim, or must purchase the minerals in order to have the 

legal right to development. Mining and safety laws also affect accessibility because some requirements and standards 

tend to decrease recovery. Additional limitations are imposed by the topography, streams, roads, and towns. 

Because of these limitations on the accessibility of oil-shale 

reserves, only an estimated two-thirds of the shale-oil, about 

800 billion barrels, will be available for mining.

The fraction of the oil-shale resource which can be 

recovered also depends on the mining method. Various mining methods are described in the chapter "Development of 

oil shale and associated minerals." The room-and-pillar mining method is relatively expensive and normally recovers 

an average of about 45 percent of the ore in the mined zone. 

Underground mining in conjunction with in situ retorts is 

less expensive than room-and-pillar mining and commonly 

recovers about 60 percent of the ore. Within the retort, the 

recovery from in situ retorts will be less than 60 percent if 

the retorts are not adjacent to each other, and if intervening oil shale is not retorted. Open-pit methods are the least 

expensive and probably can recover about 80 percent of the 

ore. If we assume that 15 percent of the ore in the basin is 

mined by room-and-pillar methods, 25 percent by in situ 

retorting, and 60 percent by open-pit methods, then about 

70 percent of the accessible ore, or about 560 billion barrels 

of shale oil would be recovered.

Finally, the recovery process depends on the efficiency 

of retorting. Aboveground retorts have demonstrated 

recoveries of about 95 percent of the shale oil in the 

feedstock. In situ retorts have lower recoveries, but 

technological improvements may result in recoveries as 

much as 75 percent in the future. A presumed recovery of 

nearly 90 percent from retorting processes indicates that 

about 500 billion barrels can be produced from the 1.2 

trillion barrels of resource (less than 42 percent of the total). 

Nevertheless the oil-shale reserves are great compared to the 

total historical production of about 120 billion barrels of 

crude oil by the United States through 1979. The oil-shale 

reserves are more than four times larger than our total 

domestically produced crude oil from 1859 through 1979. 

However, the estimated reserves of shale oil are an approximation based on numerous assumptions.

Considering the three levels of shale-oil development, the 

duration of the 500 billion barrels of reserves was calculated. 

The duration ranges from hundreds to thousands of years.

The reserves would last more than two centuries, even at 

the intense development level of 6 million barrels per day. 

Obviously, the shale oil in the Piceance basin could supply 

our Nation far into the future.

SURFACE-WATER SUPPLIES CAN PROVIDE 

WATER FOR OIL-SHALE DEVELOPMENT

The water required for oil-shale development will be derived primarily from surface- and ground-water resources. 

Use of these water supplies can affect much of the Colorado 

River basin and should be assessed in a basinwide framework. The availability of surface water in the Upper Colorado River basin was analyzed in 1979 by the Colorado Department of Natural Resources for the U.S. Water Resources 

Council. This analysis compared water requirements for oilshale development and coal gasification with various water 

resources.

The analysis projected other consumptive uses of surface 

water in the upper basin based on limited information, but 

local detailed investigations will be needed. Federal environmental regulatory laws and programs and possible interstate compact constraints on surface water were not 

considered. The analysis assumed that:

1. Surface water not presently under contract will be purchased from existing reservoirs of the U.S. Bureau of 

Reclamation and (or) new reservoir, pipeline, and pumping facilities will be constructed.

2. Future average annual natural flow of the Colorado 

River at Lees Ferry will be 13.8 million acre-feet, 

equivalent to the estimated natural flow for 1930-74.

3. Average annual depletions by surface-water uses other 

than oil-shale development and coal gasification will 

increase about 42 percent by the year 2000.

4. The Upper Colorado River Basin States will provide 

to Mexico 50 percent of the surface flow required by 

the Mexican Water Treaty; the other 50 percent of the 

required surface flow will originate in the Lower Colorado River Basin.

This analysis indicated that surface water might be obtained for oil-shale development in the White River and the Colorado River basins in Colorado. The supplies can be obtained 

by direct diversion from streams, water transfer from irrigation to oil-shale uses, a decrease in exports of water for 

municipal use, and an improvement in irrigation efficiency 

to decrease use.
128 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

TABLE 5. Potential surface-water supplies for oil-shale development in Piceance basin

DIVERSIONS FROM LOCAL STREAMS

White River in Colorado 

Colorado River in ColoradoACRE-FEET PER YEAR

172,000

68,000

TOTALTRANSFER FROM IRRIGATED AGRICULTURE

White River basin in Colorado- -

Roan and Parachute Creek basins 

in Colorado-- --- ------

TOTAL -

REDUCED EXPORT FOR MUNICIPAL USE 

Colorado River in Colorado ------

IMPROVED IRRIGATION EFFICIENCY

Colorado River Basin in 

Colorado 

240,000

37,000

10.000

47.000

53,000 to 

160,000

100,000

Deliberate weather modification in order to increase 

precipitation could result in increased surface runoff, according to the upper-basin analysis; because the techniques 

are uncertain, possible supplies resulting from this source 

were not included. The possible effects on amount and 

distribution of surface runoff from inadvertent weather 

modification by emission to the atmosphere were not 

studied.

GROUND WATER AND IMPORTED SUPPLIES 

ALSO CAN PROVIDE WATER FOR 

OIL-SHALE DEVELOPMENT

Other sources of water for oil shale include water that 

can be pumped from storage in the Green River and the 

Uinta Formations during mine drainage, deep ground-water 

supplies from storage in aquifers of Paleozoic and Mesozoic 

age in the Piceance basin or other basins in western Colorado, and imported ground and surface water.

Available water supplies from mine-drainage activities 

were estimated as follows: Natural recharge from precipitation to aquifers of the Green River and Uinta Formations 

probably averages about 36,000 acre-feet per year. The recharged water moves through aquifers to confining layers 

to zones of natural discharge where it contributes to streamflow. Exceptions are in some areas where water is evapotranspired from aquifers, but the volume of this consumption is not known.

Mine drainage will remove water from storage in aquifers 

at mine sites, and also may intercept ground water that normally would discharge to streams. Therefore, some water 

from mine drainage should be discharged back into the 

streams to replace the depleted streamflow. If the water 

resulting from mine drainage is not acceptable in quality to 

permit discharge into streams, either another source of better quality water can replace the depleted streamflow in an 

augmentation plan, or the owners of affected water rights 

can be compensated. Water law in Colorado relating to 

stream depletion is discussed in the chapter "Hydrologic 

system of the Piceance basin."

300,000

200,000

240,000

1 70,000

160,000

DIVERSION FROM 

LOCAL STREAMS

DEEP GROUND

WATER AND

IMPORTED WATE

100,000

100000 \

47,000

TRANSFER FROM

IRRIGATED 

AGRICULTURE

REDUCED EXPORT

FOR MUNICIPAL

USE IMPROVED 

IRRIGATION 

EFFICIENCY

GROUND WATER 

FROM STORAGE 

IN GREEN RIVER

AND UINTA 

FORMATIONS

Estimated maximum available water supplies for oil-shale development in Piceance basin (fig. 84).
BENEFITS, REQUIREMENTS, AND EFFECTS OF DIFFERENT LEVELS OF DEVELOPMENT 129

As much as 36,000 acre-feet of water per year from mine 

drainage may have to be returned to the streams to replace 

lost contributions of ground-water discharge to streams during oil-shale development. If Piceance and Yellow Creeks 

became losing streams because bedrock aquifers beneath 

their valleys are drained, more than 36,000 acre-feet per year 

may have to be returned to streams, to replace both the 

depleted ground-water component and the loss of direct surface runoff as water moves from the stream into the bedrock 

aquifers and mines.

The volume of water that can be drained from the fractures, pores, and solution cavities in aquifers of the Green 

River and Uinta Formations throughout the Piceance basin 

is not known. However, if we presume that a basinwide 

average of between 2 and 3 percent of the volume of the 

bedrock contains water that can be drained by pumps for 

oil-shale development, the aquifers of the Green River and 

Uinta Formations contain about 40 million acre-feet of water 

in storage.

The approximate rate at which ground water can be 

pumped from storage was calculated by dividing the 

estimated total volume of ground water by the duration of 

each level of development. The resulting steady pumping 

rates are:

Level A (200,000 barrels per day): 6,000 acre-feet per year

Level B (2 million barrels per day): 60,000 acre-feet per

year

Level C (6 million barrels per day): 170,000 acre-feet per

year

Although natural recharge replenishes and maintains the 

ground-water system, it need not be considered in those 

calculations that relate to water that can be pumped from 

storage in bedrock aquifers because of the accompanying 

natural discharge.

Additional water supplies might be obtained from other 

sources, including deep ground-water reservoirs in the Piceance basin, other geologic basins in western Colorado, and 

surface water imported from other regions. However, the 

total amount of additional water available from these other 

sources is not known.

THE LEVEL OF SHALE-OIL PRODUCTION MAY 

DETERMINE THE SOURCE OF WATER SUPPLY

A mix of water supplies was designed for the estimated 

minimum and maximum total water required for each level 

of development. Different methods of operation are likely 

to use water supplies from a combination of different sources. 

The principal sources, in a presumed order of priority, are:

1. Ground water pumped from storage in aquifers of the 

Green River and Uinta Formations.

2. Diversion from local streams.

3. Transfer from irrigated agriculture.

4. Decreased export for municipal use.

5. Improved irrigation efficiency.

6. Deep ground water and imported water.

The sources of water for oil-shale development probably 

will depend on the level of development. The small development, level A, will require only four standard-size processing plants, each producing 50,000 barrels of oil per day. The 

ranges of industrial and ancillary water requirements have 

been totaled to obtain a range of total water requirements 

of 13,000 to 45,000 acre-feet per year (see table). Presumably, this relatively small requirement would come partly 

from ground water pumped from storage for mine drainage 

at a calculated rate of 6,000 acre-feet per year, and the remainder from diversion of surface water from the White and 

the Colorado Rivers. These two sources of water can meet 

the minimum and maximum requirements for level-A 

development for 6,850 years, the expected duration of smalllevel development.

The moderate development, level B, requires an estimated 

total of 130,000 to 450,000 acre-feet of water per year. Forty 

oil-shale processing plants would be required about one 

every 40 square miles in the basin. The minimum requirement for water could be met by increased withdrawal of 

ground water from storage (60,000 acre-feet per year) and 

by surface-water diversions (70,000 acre-feet per year). 

However, the maximum requirement for level B is greater 

than the combined supplies available from ground water in 

storage and surface-water diversions. Therefore, a transfer 

from irrigated agriculture and a large decrease in export for 

municipal use would also be necessary. However, major 

changes, such as irrigation structures, deep wells, and pipelines for water development would be avoided. The water 

supplies for level B would need to be sustained for 685 years.

The intense development, level C, requires an estimated 

total of 400,000 to 1,300,000 acre-feet of water per year. 

One hundred and twenty oil-shale processing plants would 

be required, about 1 every 13 square miles in the Piceance 

basin. Minimum water requirements can be obtained by 

withdrawal of ground water from storage and by surfacewater diversions. Maximum water requirements can only 

be met by using the maximum available supplies from all 

sources, including 583,000 acre-feet per year from deep 

ground water and imported water. Supplies derived from 

improved irrigation efficiency, deep ground water, and imported water will require structural changes and capital investment. Level-C development will require dependable 

water supplies for 230 years.

The analysis of water requirements and sources indicates 

that a small level of development will not pose problems 

for water supply. Medium and intense levels of development 

will require supplies from several sources, especially if water 

requirements are near or at the maximum of the estimated 

range.
130 OIL SHALE. WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

NORTH SOUTH

Surface runoff Original water 

contributes level 

to streamflow

Ground water discharges to 

streams and contributes 

to streamflow

Ground water 

discharges 

through springs 

and probablv 

contributes to 

streamflow at 

the bottom of 

the deep canyon

Not to scale

Natural hydrologic system before oil-shale development (fig. 85).

NORTH

Pumping reduces 

ground-water 

discharge to 

stream

E

C */*: .,x Vv** > *y~ " 

C^;L>-' ^J^^^U,

/, ' /;. ' . '/////// '/'/'// /''"/',-.

//;-M^/t/'''-

////./, '// ;"',,.,

rechargeri "^F>s,.

Pumping reduces ground water in storage local

Pumping reduces 

discharge from 

springs

Confining layers

Not to scale

Effects of small oil-shale development on hydrologic system (fig. 86).
BENEFITS, REQUIREMENTS, AND EFFECTS OF DIFFERENT LEVELS OF DEVELOPMENT 131

 < X>>.--,*< V. f^ -J

r ^- -£ "-' -"-- -^

 ^^ rii*" - \ ' ,\-

/, * ///' ,,/////"

'' ' M ;/' /,- .''''. ''

NORTH

Pumping reduces ground-water 

discharge to stream and 

may induce surface water 

to flow into aquifers 

reversing the direction 

of natural flow

Pumping reduces ground water in storage

SOUTH

Pumping eliminates

most discharge

from springs \ g

Confining layers

Not to scale

Effects of moderate oil-shale development on hydrologic system (fig. 87).

r

NORTH

Pumping eliminates ground 

water discharge to stream 

and probably induces 

surface water to flow into 

aquifers, reversing the 

direction of natural flows

/ i

; ''/'

Pumping reduces ground '

water in storage over

extensive areas Orjgjna| water |eve|>

SOUTH

Pumping eliminates 

discharge from 

springs

Not to scale

Effects of intense oil-shale development on hydrologic system (fig. 88).
OIL-SHALE 

DEVELOPMENT 

LEVELS

LEVEL A 

SMALL 

DEVELOPMENT

LEVEL B 

MODERATE 

DEVELOPMENT

LEVEL C 

INTENSE 

DEVELOPMENT

PRESUMED 

RATE OF 

PRODUCTION 

FROM OIL 

SHALE PER DAY

200,000 

BARRELS

2 MILLION 

BARRELS

6 MILLION 

BARRELS

1

REQUIRED 

NUMBER OF 

PLANTS, 

PRESUMING 

EACH PLANT 

PROCESSES 

50,000 

BARRELS 

PER DAY

4

40

120

RANGE OF 

ESTIMATED 

INDUSTRIAL 

WATER 

REQUIREMENTS 

PER YEAR

9400-38,000 

ACRE-FEET

94,000- 

380,000 

ACRE-FEET

280,000- 

1,100,000 

ACRE-FEET

RANGE OF 

ESTIMATED ANCILLARY 

WATER 

REQUIREMENTS 

PER YEAR

4000-6700 

ACRE-FEET

40,000- 

67,000 

ACRE-FEET

1 20,000- 

200,000 

ACRE-FEET

RANGE OF 

ESTIMATED 

TOTAL WATER 

REQUIREMENTS 

PER YEAR

13,000- 

45,000' 

ACRE-FEET

1 30,000- 

450,000 

ACRE-FEET

400,000 

1,300,000 

ACRE-FEET

POSSIBLE SOURCES OF 

WATER SUPPLY FOR 

MINIMUM TOTAL WATER 

REQUIREMENTS 

PER YEAR

(SW = surface water; 

GW = ground water)

o o 

58 58

en r» cj to

13,000 acre -feet

en

08o"

I

5

60,000

I

130,000 acre-feet

5

en

240.000

I

5

o

160,000

I

400,000 acre-feet

POSSIBLE SOURCES OF 

WATER SUPPLY FOR 

MAXIMUM TOTAL WATER 

REQUIREMENTS 

PER YEAR

(SW=surface water; 

GW=ground water)

8

A CO

I o o §

45,000 acre-feet

5

XX

240,000

transferAgriculture

47,000

Municipal 

use

108,000 5

55,000

450,000 acre-feet

en

240,000

V

en

transfer

Agriculture

|

Municip

1 60,000

Irrigation efficiency

1 00,000

B

1 70,000

T

Deep GW andimport

8qCO 00in

1 ,300,000 acre-feet

REQUIRED LIFE 

OF DEPENDABLE 

WATER SUPPLIES, 

ASSUMING 

RECOVERY OF 

500 BILLION 

BARRELS 

OF SHALE OIL

6,850 YEARS

685 YEARS

230 YEARS

32 OIL SHALE, WATERRESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Effects of presumed levels of oil development from shale on regional water supplies (fig. 89).
BENEFITS, REQUIREMENTS, AND EFFECTS OF DIFFERENT LEVELS OF DEVELOPMENT 133

DIFFERENT COMBINATIONS OF 

OIL-SHALE MINING AND RETORTING 

METHODS ARE ASSUMED

The type of oil-shale development in the future cannot 

be predicted. Some developers prefer open-pit or underground mining with aboveground retorts; others prefer 

in situ processes. In order to estimate the impact of development on water resources, different combinations were 

presumed for each of the three levels of development.

First, 75 percent of the production was presumed to result 

from open-pit and underground mining using aboveground 

retorts, and 25 percent from in situ processes. Second, the 

proportions were reversed: 25 percent from mining using 

aboveground retorts, and 75 percent from in situ processes. 

Mining rates were calculated assuming that the average 

grade was about 0.3 barrel per ton of all mined material, 

including overburden. Furthermore, the calculations for in 

situ retorts presume that during construction about 25 percent of the rock within the retorts must be mined and 

retorted aboveground in order to prepare the in situ retorts. 

The calculations indicate that substantially less mining is required for predominantly in situ development because most 

of the extraction proceeds within oil shale that remains in 

place.

THE AMOUNTS OF RETORTED SHALE 

THAT ARE DISPOSED OF ABOVEGROUND 

DEPEND ON THE LEVEL AND TYPE 

OF OIL PRODUCTION

Mined material must be disposed of after aboveground 

retorting. Presumably the retorted shale will be backfilled into open pits, underground mine workings, or abandoned in situ retorts. However, the volume of the mined 

material commonly expands about 30 percent during 

crushing and retorting. Therefore, about 30 percent of the 

processed materials cannot be replaced in mined zones and 

must be discarded in spoil piles. The volume of retorted 

shale to be disposed of at the surface is much smaller for 

in situ processes because less material is removed from the 

mine.

Retorted shale may not be backfilled into underground 

mine workings or into abandoned in situ retorts because of 

the expense. In this case, the amounts of retorted shale 

disposed of in spoil piles aboveground will be greater than 

indicated in the table.

IMPACTS ON WATER RESOURCES 

DEPEND ON THE LEVELS AND TYPES 

OF SHALE-OIL PRODUCTION

GROUND WATER

The estimated impacts of shale-oil production on groundwater resources in the Green River and Uinta Formations can 

be summarized as follows:

1. The decrease of ground water in storage is not dependent on the types of development, because open pits, 

underground mines, and in situ retorts all need to be 

drained.

2. The decrease of ground water in storage depends on 

the level of development, as previously discussed.

3. The sources of ground-water contamination are leachate from shale piles (retorted or unretorted shale), 

leachates from abandoned in situ retorts, and leakage 

from surface ponds.

4. The contamination hazard depends on the abundance 

of leachable contaminants and the location of shale 

piles and abandoned in situ retorts.

5. For high levels of development the hazard of abandoned in situ retorts may not occur for many years. 

The widespread effects of active mine-drainage pumps 

at numerous sites throughout the basin will prevent an 

abandoned retort from flooding, even though it is no 

longer pumped. The retorts will remain dry.

DISCHARGE OF SPRINGS

The discharge of springs depends on the level, but not the 

type, of development. A decrease of ground water in storage 

decreases spring discharge and eventually will cause some 

springs to cease flowing, especially where development is 

intense.

STREAM DEPLETION

The depletion of streams that results from oil-shale development depends on:

1. The level of development and accompanying minedrainage activities.

2. The locations of mines in relation to the streams and 

springs. Mine-drainage activities that are located near 

streams and springs will deplete streams more rapidly 

than distantly located drainage sites.
134 OIL SHALE, WATER RESOURCES. VALUABLE MINERALS, PICEANCE BASIN, COLO.

OIL-SHALE 

DEVELOPMENT 

LEVELS

LEVEL A 

SMALL 

DEVELOPMENT

LEVEL B 

MODERATE 

DEVELOPMENT

LEVEL C 

INTENSE 

DEVELOPMENT

PRESUMED RATE OF 

DEVELOPMENT 

FROM OIL SHALE

200,000 

BARRELS 

PER DAY

2 MILLION 

BARRELS 

PER DAY

6 MILLION 

BARRELS 

PER DAY

PRESUMED TYPES OF 

DEVELOPMENT

OPEN-PIT AND UNDERGROUND MINING; 75 PERABOVEGROUND CENT 

RETORTING

IN SITU 25 PERCENT

OPEN-PIT AND UNDERGROUND MINING; 25 PERABOVEGROUND CENT 

RETORTING

IN SITU 75 PERCENT

OPEN-PIT AND UNDERGROUND MINING; 75 PERABOVEGROUND CENT 

RETORTING

IN SITU 25 PERCENT

OPEN-PIT AND UNDERGROUND MINING; 25 PERABOVEGROUND CENT 

RETORTING

IN SITU 75 PERCENT

OPEN-PIT AND UNDERGROUND MINING; 75 PERABOVEGROUND CENT 

RETORTING

IN SITU 25 PERCENT

OPEN-PIT AND UNDERGROUND MINING; 25 PERABOVEGROUND CENT 

RETORTING

IN SITU 75 PERCENT

AVERAGE REQUIRED 

RATE OF MINING 

IN TONS PER DAY

540,000

300.000

5,400,000

3,000,000

1 6,000,000

8,800,000

AVERAGE DISPOSAL OF 

RETORTED SHALE ABOVEGROUND IN CUBIC 

YARDS PER DAY

1 50,000

80,000

1 ,500,000

800,000

4,500,000

2,400,000

Estimated effects of presumed levels and types of oil development from shale on water resources (fig. 90 above and facing page).

3. The natural discharge from aquifers that replenishes 

the streams and springs. Pumping may cause stream 

depletion to capture all natural discharge. If extensive 

aquifer drainage occurs beneath Piceance and Yellow 

Creeks under intense development, direct surface 

runoff may recharge the aquifers and cause stream 

depletion greater than the rate of natural discharge.

PRINCIPAL SOURCE OF STREAM CONTAMINATION

Potential contamination of streams depends on the level 

and type of development. Erosion of shale piles could lead 

to contamination of streams. Contaminants leached from 

in situ retorts, shale piles, and surface ponds eventually may 

migrate to streams.

CONTAMINATION OF NEARBY LAKES

The acidification of nearby lakes that results from emissions from retorts to the atmosphere depends on the level

but not on the type of development. The relations among 

development level, atmospheric emissions, and lake 

geochemistry are poorly understood. Those lakes that are 

supplied by contaminated streams also may become contaminated. The higher levels of development may produce 

lake contamination unless control technology is improved.

WATER-RESOURCE SYSTEMS WILL RECOVER 

SLOWLY AFTER OIL-SHALE DEVELOPMENT

The recovery of surface- and ground-water systems is difficult to predict. The general weather and climate patterns 

in the region probably will not change during development, 

but the land surface and aquifer systems will undergo large 

alterations. The contamination potential related to erosion 

and leaching will change, but not predictably. However, a 

recovery to conditions similar to those originally present in 

the basin will require more time than the development 

period probably centuries.
BENEFITS, REQUIREMENTS, AND EFFECTS OF DIFFERENT LEVELS OF DEVELOPMENT 135

ESTIMATED EFFECTS OF PRESUMED DEVELOPMENT

REDUCTION OF 

GROUND WATER IN 

STORAGE PER YEAR

6000 

ACRE-FEET

60,000 

ACRE-FEET

1 70,000 

ACRE-FEET

PRINCIPAL SOURCE 

OF GROUND-WATER 

CONTAMINATION

MINOR 

LEACH ATE 

FROM SHALE 

PILES

MINOR LEACHATE 

FROM 

ABANDONED IN 

SITU RETORTS

LEACHATE 

FROM SHALE 

PILES

LEACHATE 

FROM 

ABANDONED IN 

SITU RETORTS

WIDESPREAD 

LEACHATE 

FROM SHALE 

PILES

WIDESPREAD 

LEACHATE 

FROM 

ABANDONED IN 

SITU RETORTS

DISCHARGE OF 

SPRINGS

LOCAL 

REDUCTION 

AND 

CESSATION

REDUCTION 

AND 

CESSATION IN 

SOME AREAS

WIDESPREAD 

REDUCTION 

AND 

CESSATION

STREAM DEPLETION 

PER YEAR

LOCAL AND 

MINOR

AS MUCH AS 

36,000 

AC RE- FEET 

PER YEAR

POSSIBLY MORE 

THAN 36,000 

ACRE-FEET 

PER YEAR

PRINCIPAL SOURCE 

OF STREAM 

CONTAMINATION

MINOR EROSION 

AND LEACHATE 

FROM SHALE PILES

MINOR DISCHARGE 

OF ANY 

CONTAMINATED 

GROUND WATER 

TO STREAMS

EROSION 

AND LEACHATE 

FROM SHALE PILES

DISCHARGE 

OF ANY 

CONTAMINATED 

GROUND WATER 

STREAMS

WIDESPREAD 

EROSION AND 

LEACHATE FROM 

SHALE PILES

WIDESPREAD DISCHARGE OF ANY 

CONTAMINATED 

GROUND WATER 

TO STREAMS

CONTAMINATION 

OF NEARBY LAKES

NOT LIKELY

POSSIBLE 

UNLESS 

CONTROL 

TECHNOLOGY 

IN IMPROVED

LIKELY UNLESS 

CONTROL 

TECHNOLOGY 

IS IMPROVED

THE LEVEL OF DEVELOPMENT IS UNCERTAIN

Oil-shale development is difficult to predict. National 

energy supplies probably will continue to be obtained from 

some combination of sources, including oil shale. The uncertainties in oil-shale development are related to:

1. The cost of developing shale oil in comparison to crude 

oil and other energy sources;

2. The possibility that additional energy sources will be 

discovered and induce a shift in use from one resource 

to another;

3. The partly unexplored water supplies that are 

necessary for development; and

4. The National demands for energy that are related to 

conservation, efficiency, price, lifestyle, and numerous 

unknown factors.

If oil-shale development is required for National energy 

supplies, adequate preparation time is crucial the resource 

cannot be developed properly without it.

COOPERATION IS THE KEY 

TO PROPER DEVELOPMENT

Oil-shale and other mineral development is proceeding in 

the Piceance basin, and this development probably will continue. The challenge is to develop the minerals properly. The 

uncertain requirements and impacts of the industry complicate proper development. Nevertheless, plans can guide 

the development of the minerals in spite of these uncertainties. Those plans require cooperation at several levels.

Knowledge, judgment, and insight will be acquired by 

some of the technical people who specialize in the diverse 

technologies. These characteristics need to be shared cooperatively among all, so that the resulting knowledge can be 

propagated throughout the industry.

Cooperative endeavors among the operating levels of industry and government will be needed. The mutual use of 

facilities is desirable. For example, mining, retorting, 

disposal, and transportation facilities might be shared. Water 

supplies, reservoirs, or treatment plants could be operated 

in conjunction with each other.
136 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

Finally, a cooperative commitment among the management levels of industry and government will insure that the 

minerals can be developed within the complex array of mineral, mining, water, and reclamation laws and regulations.

These are the challenges and the choices in the Piceance 

basin.

REFERENCES

Colorado Department of Natural Resources, 1979, The availability of water 

for oil shale and coal gasification development in the Upper Colorado

River Basin, Draft of Upper Colorado River Basin 13(a) assessment; 

Report to the U.S. Water Resources Council: Denver Office of the Executive Director, Summary report, 157 p.

Dolton, G. L., and others, 1981, Estimates of undiscovered recoverable 

conventional resources of oil and gas in the United States: U.S. Geological 

Survey Circular 860, 87 p.

U.S. Department of Energy, 1980, International petroleum annual 1978: 

Energy Data Report DOE/EIA-0042(78), 35 p.

For those readers who wish to pursue the study of oil 

shale, associated minerals, and their development, a list of 

publications is provided in the following section.
ADDITIONAL INFORMATION

RECOMMENDED READING

GEOLOGY AND MINERALS

Beard, T. N., Tail, D. B., and Smith, J. W., 1974, Nahcolite and dawsonite 

resources in the Green River Formation, Piceance Creek basin, Colorado: 

Rocky Mountain Association of Geologists, Guidebook No. 25, 

Guidebook to the energy resources of the Piceance Creek basin, Colorado, p. 101-109.

Bradley, W. H., 1930, The varves and climate of the Green River epoch: 

U.S. Geological Survey Professional Paper 158-E, p. 87-110.

_____1931, Origin and microfossils of the oil shale of the Green River 

Formation of Colorado and Utah: U.S. Geological Survey Professional 

Paper 168, 58 p.

Cashion, W. B., 1967, Geology and fuel resources of the Green River Formation, southeastern Uinta Basin, Utah and Colorado: U.S. Geological 

Survey Professional Paper 548, 48 p.

Donnell, J. R., 1961, Tertiary geology and oil-shale resources of the Piceance Creek basin between the Colorado and White Rivers, northwestern 

Colorado: U.S. Geological Survey Bulletin 1082-L, p. 835-891.

____1976, Global oil-shale resources and costs, in Meyer, R. F., ed., The 

future supply of nature-made petroleum and gas, technical reports: New 

York, Pergamon Press.

Dyni, J. R., 1974, Stratigraphy and nahcolite resources of the saline facies 

of the Green River Formation in northwest Colorado: Rocky Mountain 

Association of Geologists, Guidebook No. 25, Guidebook to the energy 

resources of the Piceance Creek basin, Colorado, p. 111-122.

Lillesand, T. M., and Kiefer, R. W., 1979, Remote sensing and image interpretation: New York, John Wiley & Sons, 612 p.

Lundell, L. L., and Surdam, R. C., 1975, Playa-lake deposition; Green River 

Formation, Piceance Creek basin, Colorado: Geology, v. 3, no. 9, p 

493-497.

MiLton, C., 1977, Mineralogy of the Green River Formation: The Mineralogical Record, September-October 1977, p. 368-379.

Roehler, H. W., 1974, Depositional environments of rocks in the Piceance 

Creek basin, Colorado: Rocky Mountain Association of Geologists, 

Guidebook No. 25, Guidebook to the energy resources of the Piceance 

Creek basin, Colorado, p. 57-64.

Ryder, R. T., Fouch, T. D., and Ellis, J. H., 1976, Early Tertiary sedimentation in the western Uinta basin, Utah: GeologicaL Society of America 

Bulletin, v. 87, p. 496-512.

Schaeffer, Bobb, and Martgus, Marlyn, 1965, Fossil lakes from the Eocene: 

Natural History, v. 74, p. 10-21.

Siegal, B. S., and Gillespie, A. R., eds., 1980, Remote sensing in geology: 

New York, John Wiley & Sons, 702 p.

HYDROLOGY, WATER SUPPLIES, AND WATER LAW

Colorado Department of Natural Resources, 1979, The availability of water 

for oil shale and coal gasification development in the Upper Colorado 

River basin, Draft of Upper Colorado River Basin 13(a) assessment; 

Report to the U.S. Water Resources Council: Denver, Office of the Executive Director, Summary report, 157 p.

Hynes, H. B. N., 1970, The ecology of running waters: Toronto, University of Toronto Press, 555 p.

Radosevich, G. E., and Hamburg, D. H., compilers and eds., 1971, Colorado water laws, compacts, treaties and selected cases: Report prepared 

for Colorado State Engineer, Division of Water Resources, Department 

of Natural Resources, 205 p.

Robson, S. G., and Saulnier, G. J., Jr., 1980, Hydrogeochemistry and 

simulated solute transport, Piceance basin, northwestern Colorado: U.S. 

Geological Survey Professional Paper 1196, 65 p.

Taylor, O. J., 1982, Three-dimensional model for simulating the hydrologic 

system in Piceance basin, Colorado: U.S. Geological Survey Open-File 

Report 82-637, 40 p.

Taylor, O. J., compiler, 1983, Hydrologic information needs for oil-shale 

development, northwestern Colorado: U.S. Geological Survey WaterResources Investigations Report 82-4076, 92 p.

U.S. Department of the Interior, 1974, Water for energy in the Upper Colorado River Basin: U.S. Department of the Interior, Water for Energy 

Management Team, 71 p.

Weeks, J. B., Leavesley, G. H., Welder, F. A., and Saulnier, G. J., Jr., 

1974, Simulated effects of oil-shale development on the hydrology of 

Piceance basin, Colorado: U.S. Geological Survey Professional Paper 

908, 84 p.

DEVELOPMENT OF OIL SHALE 

AND ASSOCIATED MINERALS

Dyni, J. R., 1982, Colorado nahcolite deposits: Geology and outlook for

development: American Institute of Mining Engineers Transactions, v.

270, p. 1853-1859. 

Exxon Corp., 1979, World energy outlook: New York, Exxon Corp.

Background Series, Public Affairs Department, 32 p. 

Hendrickson, T. A., compiler, 1975, Synthetic fuels data handbook:

Denver, Cameron Engineers, Inc., 297 p. and appendix. 

Lewis, A. E., 1979, Oil from shale The potential, the problems, and a

plan for development: Energy, Great Britain, Pergamon Press, v. 5,

p. 373-387. 

Meyer, Randall, 1981, Energy resource development in the western states

(presented at Colorado School of Mines, Golden, April 2,1981): Houston

Tex., Exxon Co., Public Affairs Department, 18 p. 

Nowacki, Perry, ed., 1981, Oil shale technical data handbook: Park Ridge,

N.J., Noyes Data Corp., 309 p.

Occidental Petroleum Corp., 1980, Shale oil: Grand Junction, Colo., 28 p. 

Rickert, D. A., Ulman, W. J., and Hampton, E. R., eds., 1979, Synthetic

fuels development, earth-science considerations: U.S. Geological Survey

Special Report, 45 p. 

Russell, P. L., 1979, History of western oil shale: East Brunswick, NJ:,

The Center for Professional Advancement, 152 p. 

U.S. Congress, Office of Technology Assessment, 1980, An assessment of

oil shale technologies: Washington, D.C., U.S. Government Printing

Office, 517 p.

139
140 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.

IMPACTS OF OIL-SHALE DEVELOPMENT

Bates, E. R., and Thoem, T. L., eds., 1980, Environmental perspective on 

the emerging oil shale industry: Cincinnati, U.S. Environmental Protection Agency, Office of Research and Development, Oil Shale Research 

Group, EPA-600/2-80-205a, 32 p.

Colorado Energy Research Institute and Colorado School of Mines, 1981, 

Oil shale 1982, a technology and policy primer: Golden, Colorado 

Energy, 93 p.

Likens, G. E., Wright, R. E., Galloway, J. N., and Butter, T. J., 1979, Acid 

rain: Scientific American, v. 241, no. 4, p. 43-51.

Shih, C. C, Cotter, J. E., Prien, C. H., andNevens, T. D., 1979, Technological overview reports for eight shale oil recovery processes, prepared 

in cooperation with Denver Research Institute: Cincinnati, U.S. Environmental Protection Agency, Office of Research and Development, 

Partial fulfillment of EPA Contract 68-02-1881, EPA-600/7-79-075,107 p;

available from National Technical Information Service, Springfield, Va, 

as report PB-295 665/4ST, 115 p.

Slawson, G. C., Jr., and Yen, T. F., eds., 1979, Compendium reports on 

oil shale technology, prepared by General Electric Co. TEMPO: Las 

Vegas, U.S. Environmental Protection Agency, Office of Research and 

Development, partial fulfillment of EPA Contract 68-03-2449, 

EPA-600/7-79-039, 202 p; available from National Technical Information Service, Springfield, Va., as report TB-279/6BE.

U.S. Environmental Protection Agency, 1977, Oil shale and the environment: Washington, U.S. Environmental Protection Agency, Office of 

Research and Development, EPA-600/9-77-033, 29 p.

U.S. Environmental Protection Agency, Oil Shale Research Group, 1981, 

Perspective on the emerging oil shale industry: Cincinnati, U.S. Environmental Protection Agency, EPA 625/9-81-005, 18 p.

Western Colorado Congress, 1981, Oil shale, a citizen's perspective: Montrose, Colo, 16 p.

142 OIL SHALE, WATER RESOURCES, VALUABLE MINERALS, PICEANCE BASIN, COLO.
EPILOGUE

By O. JAMES TAYLOR

The mineral resources of the Piceance basin are an abundant and varied National treasure. Studies of the basin have 

provided information on the interwoven geologic and 

hydrologic processes that caused the minerals to accumulate. 

An awareness of these processes is helpful in understanding 

the occurrence and association of these minerals and in 

predicting where they may be found.

The desirable level of mineral development including the 

fundamental question of whether or not the minerals should 

be developed is complex. Development will result in a 

variety of National benefits accompanied by regional disadvantages. The relative benefits and disadvantages also will 

depend on the duration of development, itself a function 

of the level of development.

Plans to develop the minerals can be improved by considering the conditions of mineral deposition, burial, and 

structural deformation. For example, mining and retorting 

can be designed to improve recovery, maintain safety, and 

reduce many undesirable effects of development in the

basin if the available information is used. Waste materials 

that result from mineral development will change the land 

surface of the basin, its water resources, and atmospheric 

conditions. The disadvantages of the changes can be reduced 

by actions that consider the interactions between the waste 

materials and the hydrologic systems.

Water resources for oil-shale development are paramount. 

The ground water that occurs with the minerals is a mixed 

blessing; it must be drained before mining but it will provide part of the supplies needed for development. The availability of additional supplies from streams, regional 

ground-water reservoirs, and other sources from which 

water might be imported, is uncertain.

Proper development will require additional information 

to ensure that the benefits outweigh the disadvantages. This 

information can be provided by Earth scientists those 

remarkable men and women in government, industry, and 

universities whose imaginative and comprehensive investigations have provided the material discussed in this volume.

143