University of Nevada Reno HYDROLOGY and WATER

University of Nevada Reno

HYDROLOGY AND WATER BUDGET OF OWENS LAKE, CALIFORNIA

A thesis submitted in partial fulfillment of the requirements for the degree of Masters of Science in Hydrology /Hydrogeology

By Thomas J. Lopes v»' October, 1987 mimes UlRAfcY The thesis of Thomas J. Lopes is approved: NlV s i s

3 3 ( o < ) \

Thesis Advisor

University of Nevada Reno October, 1987 ACKNOWLEGDEMENTS

Funding and data collection for this thesis was provided by the following individuals and organizations. I would like to thank:

William Hutchison, Inyo County Hydrologist

Los Angeles Department of Water and Power

William Cox, Great Basin Air Pollution Control District

Ellen Hardebeck, Great Basin Air Pollution Control District

Patricia Casey Knapp, Environmental Monitoring Services, Inc.

Todd Mihevc, Desert Research Institute Hydrogeologist

Scott Tyler, Desert Research Institute Hydrogeologist

Water Resource Center, Desert Research Institute

Special thanks to my major advisor Dr. Gilbert Cochran and Brad Lyles, Desert Research Institute hydrogeologist. This project would have been much more difficult without Dr. Cochrans’ guidence and Mr. Lyles computer expertise.

Finally, I would like to thank my parents for their continued support of my education. In times of doubt, they always gave me the encouragement needed to carry on with my work. ABSTRACT

Owens Lake, California, is a hydrologically closed basin in southern Owens Valley. Diversion of water out of the basin has resulted in lake dessication and salt crust formation on the exposed lake bed. Salt crusts are most extensive along the southeastern to west lake bed due to small volumes of runoff from the Coso Mountains and diversion of Sierra Nevada runoff. Lesser amounts of salt- crust along the northern lake bed are due to large volumes of runoff from Inyo Mountains and coarse grained, shallow sediments inhibiting capillary action from • §roundwater. Calcite precipitation controls trends in water chemistry, lead ing to sodium and bicarbonate dominated waters. Evaporation of inflow should lead to halite and trona precipitation. Extensive aquifers are at least 450 feet deep. Estimated mean annual flow into Owens Lake basin is approximately 169,000 acre-feet with a range of 185,000 to 154,000 acre-feet. IV

Table of Contents

SIGNTTURE PAGE...... ACKNOWLEDGEMENTS ...... ABSTRACT...... “ TABLE OF CONTENTS ...... U1 LIST OF FIGURES ...... " LIST OF TABLES...... ZZZZZ...... vii LIST OF APPENDICES ...... ' " ...... “ LIST OF PLATES ...... x INTRODUCTION ...... XI CLIMATE AND PRECIPITATION...... 1 MODERN CLIMATE ...... 3 PALEOCLIMATALOGY ...... ZZZZZZ'...... 3 GEOLOGY OF OWENS LAKE BASIN Z Z Z Z Z Z Z Z Z 1 ...... 6 historic.at geology ...... g Coso Formation ...... STRUCTURAL GEOLOGY OF OWENS VALLEY...... jj Subsurface Structure...... Surface Faulting Structure Folds ...... 2g 15 Lake Margin Structure ...... LITHOLOGY...... 17 ...... 27 Sierra Nevada Mountains Inyo Mountains ...... Coso Mountains ...... Valley Fill ...... Salt Crust ...... 23 Upper \ alley Lake Deposits ...... HYDROLOGY AND HYDROCHEMISTRY OF OWENS LAKE BASIN...... Z PREVIOUS STUDIES ...... 25 Mountain Hydrology Mountain Runoff Basin Hydrology ...... Precipitation ...... Owens River ...... Owens Lake ...... 28 Evaporation ...... 28 V

Evapotranspiration ...... Groundwater Recharge ...... 30 Groundwater Discharge ...... 3~ Closed Basin Sedimentology ...... 3^ Alluvial Fans ...... Dry Mudflats ...... 36 Ephemeral Saline Lakes ...... 36 Perennial Saline Lakes ...... 37 Dune Fields, ...... 37 Perennial Stream Floodplain ...... Springs ...... ^ Shoreline Features ...... 3g Playa Surface Morphology ...... y Classification ...... 3g Morphologic Changes ...... HYDROSTRATIGRAPHY ...... 42 Owens River ...... 42 Delta Region ...... 42 Channel Deposits ...... Alluvial Fans...... ^ Volcanics ...... Lake Clays .. ^ Salt Crust ...... 49 Aquifer Continuity and Correlation ...... SURFACE MORPHOLOGY ...... Sandfiats ...... Salt Crusts ...... Mudflats ...... ^ Beach Ridges ...... ^ Dunes and Megaripples ...... Salt Pan ...... ^ Spring Mounds ...... HYDROGEOCHEMISTRY...... 65 6° West Lake Bed Margin Northeast Lake Bed Margin ...... ^ Southest Lake Bed Margin ...... _ Brines ...... SALT NORM...... “2'2 CaCO^Na^CO^ ...... _ MgCOr NaCl ...... NdCl-NaoCOz ...... 78 VI

Chemical Trends Isotopes ...... '8 Salt Inflow ...... 8^

WATER BUDGET ...... 87 gy Hydrologic Boundaries ...... Base Period ...... 88 Inflow Components ...... 89 Precipitation ...... Runoff ...... 89 ...... g2 Owens River ...... ^ Subsurface Flow ...... Groundwater Basin T ...... 106 Lake Precipitation ...... ^ Alluvial Fan Precipitation ...... 1Q6 Mountain Runoff ...... ' ’ Subsurface Flow ...... 110 Springs and Wells ...... Phreatophyte Evapotranspiration ...... 222 Bare Soil Evaporation ...... ^ Owens Lake Spring Inflow ...... Owens Lake Boundary ...... Lake Evaporation ...... SUMMARY AND CONCLUSIONS ...... ’ ...... 113 REFERENCES ... 119 ...... 122 Vll

List of Figures

1. Owens Lake Location Map ...... 2. Profile of Precipitation Stations ...... 3. Principal Fault Zones of Owens Valiev 4. Fault Offsets of Cenozoic-PreCenozoic Contact ...... ,9 5. Gravity Profile Reference Map ...... 6. Gravity Profile A-A’ along Highway 136 ...... 22 7. Gravity Profile B-B’ along Owens Dry Lake #1 8. Gravity Profile C-C’ along Olancha ...... 9. Lake Margin Faults ...... IQ. Lake .Area-Capacity Curves H* Evaporation vs. Specific Gravity ...... 2q 12. Generalized diagram of playa environments ...... 25 13. Deltaic sedimentary environments ...... 2g 14. Trilinear Diagrams of Owens Lake Water Chemistry ...... R~ 15. d lsO vs. Chloride .:...... 16.^ Sodium vs. Chloride ...... *...... 17. Total Carbonate vs. Chloride ...... 18. Potassium vs. Chloride ...... 81 19. Sulfate vs. Chloride ...... 83 20. Owens Lake Isotopes vs. Craigs’ Meteoric Water Line ...... 85 21. Owens Lake Water Budget Flow Diagram ...... !.*!.*.*.*.*.*.*.*".*.*..... on 22. Owens Lake Isohyetal Map ...... ;...... ^ 23. Linear Regression of Precipitation vs. Elevation '...... 93 ! l ? ™ VO°d Creek Discharge at the UPPer G^ e , 1939-40* to* 1979-80..... 2o. Cottonwood Creek Discharge at the Aqueduct, 1939-40 to 1979-80

1983^84tODWO°d CreCk Stream L°SS VS> T°tal Dischar§e; 1935-36 to...... ^ ****************************"***••••••••••••••••••••••••••••••••* Q0 2/. Percent stream loss vs. Total Discharge, Cottonwood Creek ...... 96 28. Ash Creek Discharge at the Aqueduct, 1939-40 to 1979-80 ...... gg 29. Braley Creek Discharge at the Aqueduct, 1939-40 to 1979-80 ...... 100 30. Lubkm Creek Discharge at the Aqueduct, 1939-40 to 1979-80 ...... 101 31. Carrol Creek Discharge at the Aqueduct, 1939-40 to 1979-80 ...... ’* 101 32. Owens River Discharge at Keeler Bridge, 1939-40 to 1979-80 ...... 105 33. Owens Lake Elevations, 1939-40 to 1979-80 ...... *** n 4 34. Owens Lake Volume, 1939-40 to 1979-80 ...... 114 35. Owens Lake Area, 1939-40 to 1979-80 ...... _ ...... llo vm

36. Mean Monthly Owens Lake Elevations ...... 37. Mean Monthly Owens Lake Volume ...... U ° 38. Mean Monthly Owens Lake Surface Area ...... 116

l List of Tables

1. Precipitation Station D ata ...... 2. Hydrologic Regimes of Searles Lake 3. SALT NORM Results ...... 4. Groundwater Basin Budget ......

List of Plates

1. Reference Point Map ...... 2. Owens Lake Structure and Sedimentary Facies Fence Diagram ...... "["’pocket 3. Fence Diagram Reference Map ...... -pocket 4. Owens Lake Water Chemistry Map ..."[[[[[[[[[[[[...... POC*et 5. Owens Lake Playa Environments ...... "[[[[[[[[[[[[[[[[[...... 6. Owens Lake Drainages Map ...... ["[[[[[[[[[[...... P°cket 7. Owens Lake Playa Environments and Drainages ...... ["[[[[."."[[.'[.'[.’[.’[[[[[.'[.pocket INTRODUCTION

Owens "Galley is a hydrologically closed basin almost entirely within Califor nia (see Figure 1). It is located between the Sierra Nevada on the west and Inyo and White Mountains to the east. Total area of Owens Valley is 3.197 square miles (Banks, 1960). The area in California contains 2,409 square miles of moun tain and foothills and 724 square miles of valley and mesa lands. The Owens Valley groundwater basin extends 120 miles from Haiwee Reservoir to the California-Nevada border and is two to 18 miles wide. Owens Lake is located in the most southern end of the valley. Elevation ranges from 3.551.5 feet at Owens Lake to 14,495 feet at Mount Whitney. Highway 395 is the main transportation route through the valley.

Owens Valley receives large volumes of inflow from runoff from the east slope of the Sierra Nevada. In the early 1900’s, the City of Los Angeles began buying land m Owens Valley to acquire water rights and constructing the. Los Angeles Aqueduct (Aqueduct) for water export. The Aqueduct was completed in 1913 and is operated by the Los Angeles Department of Water and Power (LADWP)i

Since the Aqueduct’s construction, two major additions have increased the volume of export and capacity of the Aqueduct. In 1940, Mono Basin was hydro logically connected with Owens Valley by completion of the Mono Craters Tun nel. Surface runoff within Mono Basin has since been diverted through the tun nel to augment diversions in Owens Valley. The second addition was the con struction of the second aqueduct, completed in 1970. The Aqueduct’s capacity was increased to handle increased groundwater pumping in Owens Valley and increased surface diversions form the Owens Valley and Mono Basin. 2

rIGURE 1. Owens Lake Location Map. 3

CLIMATE AND PRECIPITATION

MODERN CLIMATE

Precipitation within Owens Valley is generally greater than other parts of the Basin and Range due to its proximity to the Pacific Ocean. Variation in amount, distribution, and source of precipitation is largely due to orographic effects of the Sierra Nevada. Temporal variation in precipitation reflects the different origin of storm systems that contribute to total annual precipitation. Annual precipitation in the Great Basin consists of three components: the Pacific Ocean component, the Gulf component, and the Continental component (Hough ton, 1969).

The most significant component originates in the Pacific Ocean and most often occurs from October through June (Houghton, 1969). The extent and fre

quency to which these storms move south controls the amount of precipitation in the Sierra Nevada and western Owens Valley (Lee, 1912), Precipitation along the eastern slopes of the Sierra Nevada decreases sharply with elevation. This "rainshadow effect" is shown in Figure 2. Station data were taken from LADWP (1972) and are given in Table 1.

The second most important precipitation component is the convective thun derstorms that originate m the Gulf of Mexico (Houghton, 1969). These storms, termed "Sonoras", occur from mid-July to September and seldom move west of

the Sierra Nevada (Houghton, 1969; Lee, 1912). Lee (1912) describes Sonoras as a series of small storms that move up Owens Valley, favoring neither the Sierra Nevada or Inyo Mountains. station elevation (feet) 5

Table 1. Precipitation Station Data (after LADWP, 1972)

Station Station Mean Annual Elevation Distance from Latitude Longitude Number Name precip. (inches) (feet) crest (miles) 1 Rock Creek 16.32 37° 27' 118" 45' 9,700 2.0 2 Lake Sabrina 16.97 37° 13' 118" 37' 9,100 3.4 3 South Lake 17.84 37° l l ' 118" 34 9,620 5.6 4 Bishop 5.89 37° 2 l' 118" 24' 4,150 20 4 Big Pine Power 0 8.75 Plant No. 3 37" 08' 118" 20' 5,400 16.0 Big Pine Creek

0 ^ co

15.65 o 05 at Glacier Lodge 118" 26' 8,200 7.6 Tinemahra 7 6.60 37" 04' Reservoir 118" 14' 3,850 10.8 Los Angeles 5.74 Aqueduct Intake 36" 58' 118" 13' 3,825 9.6 9 Independence 5.01 36" 48' 118" 12' 3,950 13.2 10 Alabama Gates 3.80 36" 4 l' 118" 05' 3,675 12.0 11 Lone Pine 4.38 36" 36' 118" 04' 3.661 6.0 12 Cottonwood Gates 6.05 36" 25' 118" 02' 3,775 8.0 13 North Haiwee 5.33 36" 14' 117" 58' 3,850 7.0 14 South Haiwee 5.90 36" 08' 117" 57' 3,800 6.2 Haiwee Power 15 5.57 36" 07' House 117" 57' 3,570 4.5 16 Little Lake . 6.54 35" 57' 117" 56' 3,500 4.5 Cottonwood Creek 17 15.69 36" 29' at Golden Trout 118" l l ' 10,600 9.0 Cottonwood Power 18 5.60 36" 27' House 118" 03' 3,790 21.5 19 Onion Valley 24.64 36" 46' 118" 20' 8,850 24.5 20 White Mountain #2 16.62 37" 35' 118" 14' 12,470 19.0 21 White Mountain #1 13.43 37" 3O' 118" l l ' 10,150 29.0 6

Rainfall distribution is scattered due to paths of individual small storms. Approximately two Sonoras occur each year and comprise a larger proportion of annual rainfall along eastern Owens Valley than winter storms (Lee, 1912).

Summer thunderstorms are the third precipitation component. Moisture for these storms is derived from the recycling of snowmelt and moisture from the other two components (Houghton, 1969). These storms form at high elevations in the Sierra Nevada from July to August. Lee (1912) notes that summer thun

derstorms tend to be more frequent and of greater intensity after dry winters.

These storms form a greater proportion of annual precipitation along eastern Owens Valley than winter storms.

PALEOCLIMATOLOGY

The climatic history of the Owens Lake region in the last 3.2 million years (m.y.) has been deduced from the stratigraphy of Searles Lake. Searles Lake is the fourth basin in the series of Pleistocene lakes headed by Russel Lake (Mono

Lake) and terminating in Death Valley. Lake stages at Searles Lake are sensitive to climatic changes because of the storage capacities of the upper three lakes in the series. Inflow to Searles Lake depends on overflow from the other lakes and therefore is first affected by a decrease in flow in the system of lakes. Changes in

climate are recorded in the stratigraphy by sediments and minerals indicative of certain climates and flow regimes.

Smith (1979, 1984) has been the primary investigator of Searles Lake. His reconstruction of the region’s paleoclimate differs from studies of nearby Russel Lake of the Mono basin between 20,000 and 11,000 years ago (Department of Energy, 1987). The discrepancies indicate that more work needs to be done in the southern Great Basin to accurately characterize the region’s paleoclimatology. I

Smith (1984) characterized the climatic history of Searles Lake for the last 3.2 m.y. from a 930 meter core drilled near the center of the lake down to the granitic basement. He identified nine distinct paieohydrologic regimes from the long, continuous core. Each regime lasted 0.12 to 0.76 m.y. and is classified as either •wet", "intermediate", or "dry" (similar to today). According to Smith (1984), short term climatic cycles of up to 100,000 yearn did not affect lake levels significantly enough during wet and dry climatic regimes to produce changes in

lake sedimentology. Sedimentation during intermediate regimes was more sensitive to climatic changes.

Smith et al. (1983) separated the upper 693 meters of lacustrine sediments into 14 informal stratigraphic units. Smith (1984) grouped the units into nine climatic regimes (Table 2). Lacustrine marl and green, brown, and olive, clays dominate the stratigraphic units assigned to wet regimes; salt beds and and inter- layered dark brown muds were assigned to dry climates; and interbedded salts and olive brown to brown muds indicating alternating wet and dry periods were assigned to intermediate regimes.

.Table 2. Hydrologic Regimes of Searles Lake (after Smith. 1984)

Hydrologic regime Age of Base Duration of regime Number uli41»n,r , Character (mv) (my) I Dry- 0.0l±0.002 0.01 II Intermediate 0.13±0.02 0.12 in Intermediate 0.31+0.10 0.18 IV Dry 0.57±0.12 0.26 v Intermediate 1.00±0.06 0.43 VI W et 1.28±0.08 0.28 VII Intermediate 2.04±0.01 0.76 vm Dry 2.56±0.05 0.52 K W et 3.18+0.04 0.62 8

Smith et al. (1983) estimated average apparent sedimentation rates at 9 inches/1000 years for the entire core. Most older sediments have apparent rates of 4 to 12 mches/1000 years and younger, less compact sediments average 21 mches/1000 years. Smith’s estimations are based on paleomagnetically esta blished horizons, carbon-14 dating, and interpolation and extrapolation from the age of bases between the climatic regimes.

Sediments deposited in the last 140,000 years at Searles Lake have been stu died in the greatest detail (Smith, 1979). During the early Wisconsin epoch, greater than 100,000 years ago, Searles Lake filled two or more times to overflowing. Overflows were separated by a recession of the lake. This is evi denced by alluvium, well developed soils, and thin salt layers. During the Middle

Wisconsin period, 24,000 to 33,000 years ago, seven brief lake recessions alter nated with six high lake stages of long duration. During the late Wisconsin

period, 10,000 to 24,000 years ago, a large lake occupied the Searles basin and probably overflowed part of the time. Two partial recessions are suggested by alluvium and gravel lag, but no salt layem are present. In the last 10,000 yearn, at least one small lake occupied the basin.

GEOLOGY OF OWENS LAKE BASIN

HISTORICAL GEOLOGY

The early geologic history of Owens Lake is the best documented period of the basin’s history. No detailed work has been done on the geologic history of late Pleistocene to recent lake sediments. However, Searles Lake has been studied m detail and inferences can be made about Owens Lake from this work and from core logs from Owens Lake. Coso Formation

The Coso Formation is the oldest Tertiary sedimentary deposit and is exposed along Owens Lake shorelines and the Coso Mountains. Intercalated volcanics and vertebrate fossils found in the Coso Fm. heip constrain the age of deposition and events that may have caused deposition of the various rock types. The Coso Fm. consists of at least 500 feet of arkosic and lacustrine deposits (Bacon et. al., 1982). These volcanics consist of dacite, basalt, and rhyolite flows and domes overlying and intruded into the Coso Fm.

Based on K-Ar dating of the volcanics, the Coso Fm. is approximately 2.5 to at least 6.0 m.y. (Miocene-Pliocene; Bacon et al., 1982). Fluvial and lacustrine deposits stratigraphicaliy underlying basalt flows dated at 6 m.y. indicate the basin was occupied by a lake and was the site of sedimentation at least 6 m.y. ago. Arkosic and pyroclastic sediments were deposited during the contemporane ous eruption and intrusion of mafic and silicic magmas. The shift from volcan-

ism “ d M e n t a t io n on the north end of the Coso Mountains (5 to 6 m.y.) to block faulting, volcanism, and sedimentation within the range (2.5 to 4 m.y.) would result in increased sedimentation in the basin.

STRUCTURAL GEOLOGY OF OWENS VALLEY

Owens Valley is the western most basin of the Basin and Range Province. It is located approximately half way in the Winnemucca-Ventura zone, a belt of high seismic activity from near Ventura, California to Winnemucca, Nevada

(Carver, 1969). Owens Lake is bounded on the south, east, and west by escarp- ments 3,500 to 11,500 feet above the basin floor. 10

The structure of the Owens Valley has been described by Carver (1969). Three principal fault zones occur within the valley. All principal zones have been active during the Quaternary, with the central zone the most active and the eastern zone the least active. Locations of the principal fault zones are shown in Figure 3.

Subsurface Structure

Deep structure of the Owens Lake b ^ in has been described by Pakiser et. al. (1964), who conducted a gravity survey of Owens Valley. The approximate amount of offset was confirmed in this stndy from profiles across the basin using Bouger gravity maps made in 1984 by the U.S. Geological Survey (USGS) and a

Taiwan! 2-D model. Locations of the faults displacing the pre-Cenozoic-Cenozoic rock contact in Owens Lake are shown in Figure 4. Gravity profiles of the 1984 survey are shown in Figures 5 through 8.

The north-south trending Sierra Nevada range front fault zone displaces the valley fill sediments more than 2,000 feet in the Owens Lake area with gradually

decreasing offset to the north. Near Olancha, the fault zone curves east in a senes of branches. The zone either dies out here or intersects the central fault zone.

The central fault zone forms the eastern boundary of the Alabama Hills. The east block has been downdropped at least 6,000 feet in the lake basin with increased displacement to the north. Approximately 8,000 feet of offset has occurred near Lone Pine. Gravity profiles of the 1984 survey data reveal the presence of a large fault block that was not detected by Pakiser et. al. (1964). FIGURE 3. Principal Fault Zones of Owens Valley (after Carve

mgal IUE . rvt poie -* ln Hgwy 136. Highway along A-A* profile Gravity 6. FIGURE FIGURE 5. Gravity Profile Reference Map, Reference Profile Gravity 5. FIGURE

Calculated depth to bedrock (feet) 1 3 m g a l ^ ^ IUE . rvt poie C’ ln Olancha. along ’ -C C profile Gravity 8. FIGURE

et rm rgn ml tc marks) tick (mile Origin from Feet ^^^a0 ° ° ^ ^ ^ - ---- obsgrav - LEGEND depth & colcgrav feO

- 9 0 0 -95 9000 0 0 0 -9 8500 0 0 5 -8 8000 0 0 0 -8 7500 0 0 5 -7 - - C' 6000 0 0 -6 5500 0 0 5 -5 5000 0 0 0 -5 4500 0 0 5 -4 4000 0 0 0 -4 3500 0 0 5 -3 3000 0 0 0 -3 2500 0 0 5 -2 -2000 -2000 - - 0 0 -5 10000 7000 7000 6500 1500 1500 1000 1000 o

Calculated depth to bedrock (feet) Calculated depth to bedrock (feet) 1 4 15

Th,s fault block is the most significant subsurface feature. It is located approxi mately in the center of the lake and is about 2,500 to 4,000 feet beneath the lake surface. This fault block could be the southern extension of the Alabama Hills.

Along the west margin of the Inyo Mountains is a large fault offsetting the valley fill by approximately 5,000 to 7.000 feet. This approximately defines the eastern edge of the valley.

Surface Faulting Structure

Surface faulting features along the Sierra Nevada range front are confined to areas adjacent to the foot of the mountain in a one mile wide belt. Most Quater nary scarps occur near or on the alluvium-bedrock contact. Fault planes are not well exposed in stream channels and their orientations have been estimated by Carver (1969) to be about 60-80 degrees for the underlying bedrock fault and nearly vertical through the alluvium.

Few active faults exist along the Inyo Mountain range front to produce large scarps. Isolated scarps in alluvium are short and small with the exception of a large, discontinuous scarp that extends about one mile northeast of Keeler (Plate 1) and trends south, gradually curving west and merges into the fault tone at the base of the Coso Mountains. Most displacement is in the older alluvium and no evidence of recent activity exists.

On the east side of Owens Lake, just west of the lake margin, is a fault trending N30W (Carver, 1989). It extends from near the mouth of Owens River

to Lower Centennial Flat. West of Keeler, a branch of this fault trends south to the base of the Coso Mountains, intersecting a series of northeast trending faults that form the southeast boundary of the lake basin. 16

Obhque and dip-slip scarps of the Coso Mountain front offset alluvia] and lacustrine sediments along the northwest flank of the range. These scarps exist as: 1) long, linear, dip-slip or oblique slip faults trending parallel to the range with the basin side blocks downdropped: and 2) a series of horst and graben structures trending N-S offsetting older alluvium, the Coso Fm., and overlying basalts.

The central fault zone has been the most active from late Quaternary to recent. Oblique and dip-slip movement occurs along a continuous series of N-S trending scarps. The faulting can be divided into two patterns: l) a series of oblique slip faults in a long, narrow area approximately defines the west margin of the lake: and 2) faults occurring in small areas with complexly oriented scarps and grabens. These areas are located at the southern end of the Alabama Hills and intersection of the Central fault zone and Coso Mountain front zone.

ihe spatial relations between basement faults and surface faults indicate that the basement faults extend all the way to the surface (Carver, 1969). This suggests the faults are nearly vertical through 3.000 to 8,000 feet of sediments.

Folds

Young and old lake sediments of the central zone have been deformed into broad domes and basins 1,000’s of feet across (Carver, 1969). Domes usually occur over or adjacent to fault traces north and south of Bartlett Point, east of the lake shore near Cottonwood Creek, and north of the southern shore where the Central zone intersects the lake. Domes and basins are elongate N-S , parallel to the fault zone axis. The largest basin is 7,000 by 3,000 feet and is the lowest point in Owens Lake. 17 Lake Margin Structure

Surrounding Owens Lake bed is a narrow, discontinuous belt (1/2 to 1 mile wide) of distinctly shaped grabens (see Figure 9). These grabens occur singly or m groups of long, narrow, often sinuous blocks parallel to the lake margin. Offset is primarily dip-slip with the basin side downdropped.

Carver (1969) assumed that the marginal grabens are latest Pleistocene to recent features of the lake basin. Many of these structures reportedly developed during the great 1872 quake. All marginal grabens are located below late Pleisto cene high lake level and probably below neoglacio pluvial high lake level since none of the grabens appear to have been reworked by waves or filled with lake sediments. 1 his indicates these grabens formed in the last few thousand years.

The Pattern of marginal grabens does not correspond with the major base ment fault zones or trend parallel to mountain ranges. This indicates that the grabens were produced from differential movement of the alluvium and lake sedi ments. Mechanisms for this movement may include gravity compaction and draining of water from marginal sediment and a decrease in buoyancy of the sedi ments.

LITHOLOGY

Lithology of the mountains surrounding Owens Lake includes igneous, metamorphic, and sedimentary rocks. These source rocks are from the Sierra Nevada, Coso, and Inyo Mountains and are located respectively to the west, south, and east of the lake. Lithology of the Owens Lake basin is the primary control on the chemistry of waters in the basin. Waters originating from the mountains acquire their chemical composition by dissolving some of the rock which the water flows over and through. 18

FIGURE 9. Location of Lake Margin Faults (after Carver, 1969) . 19 Sierra Nevada Mountains

The Sierra Nevada is a calc-alkaline batholith formed during the Cretaceous (Levin, 1878). These intrusives consist mostly of granodiorite, granite, and quartz monzonite (d„ Bray and Dellinger, 1981). The Whitney Granodiorite and Granite of Carrol Creek are the most widely exposed plutons west of Owens Lake.

The batholith intruded Paleozoic and Mesozoic metasedimentary and meta- volcanic rocks which occur as roof pendents and septa. Paleozoic rocks consist

mainly of hue grained hornblende-hornfels facies metamorphics of peletic, sili ceous, and calcareous sediments. Mesozoic rocks consist of metavolcanics of fine grained dacite, andesite, and rhyolite flows and tuffs with little calcareous sedi ments. Metavolcanics crop out along the crest of the Sierra Nevada, in Braley and Ash Creek drainages, and in the western part of the Alabama Hills.

Inyo Mountains

The Inyo Mountains consist of granitoids in the northern part of the range

granitic outcrops m the Owens Lake basin (Merriam, 1963; Hall and Mckevitt, 1962). Late Tertiary olivine basalts cover large areas of the Inyo Mountains six miles south of Cerro Gordo Mine.

The southern Inyo Mountains bordering the lake basin are comprised of Paleozoic to Triassic metavolcanics and sediments (Pakiser et al„ 1964; Merriam, 1963; Hall and Mckevitt, 1962). Paleozoic sedimentary rocks are mostly of

marine origin and consist of limestone, dolomite, shale, conglomerate, and quartzite. Upper Triassic rocks consist of andesite, rhyolite, metatuff, sandstone, limes stone, dolomite, shale and quartzite. Dolomite and limestone are the dominant lithologies exposed east of Owens Lake. 20

Small to intermediate site granitoids, aplites, and a large number of andesite ekes have intruded the sediments and metavolcanics. This has resulted in local contact metamorphism to marble and schist and produced hydrothermal altera- t,on and mineralization of the area. The Cerro Gordo Mine and Darwin Mining

District in Centennial Flat extracted mainly argentiferous galena and zinc car bonate ores (Merriam, 1963; Hall and Mckevitt, 1962). Copper, iron, and zinc sulfides, lead and copper carbonate, arsenical and antimonial lead, and gold were byproducts or gangue minerals.

Coso Mountains

The Coso Mountains, forming the southern boundary of the lake basin, con- s.sts of a granitic core covered by volcanics and lake bed deposits of the Coso

Formation. Composition of the granitic basement ranges from gabbro to granite (Duflield and Bacon, 1981). The granitic core is the most widely exposed rock

type w,thm the hydrographic divide. Volcanics overlying the granitics include olivine and clinopyroxene basalts, dacite, and rhyolite hows and pyroclastics.

Valley Fill

Cenozoic rocks and sediments of Owens Valley and the lake basin consist of lacustrine and alluvial sediments and volcanics. The oldest known Cenozoic rocks are the members of the Coso Fm„ exposed in the southern end of the valley m’ and P^Pberal to, the Coso Mountains.

The Coso Fm. has an exposed thickness of at least 500 feet (Pakiser et al

1964)' The l0TO ~ U“ °f the - s i s t s of lacustrine and fluvial sedi ments and is overlain by alluvial and pyroclastic deposits. The sequence has been intruded by dikes and domes of basaltic, dacitic, and rhyolitic composition. 21

Pre-W iscotisii, lake sediments are exposed around and within the Owens Lake margin (Carver, 1969). These lacustrine sediments are mostly medium to thinly bedded sequences of silt and clay with few beds of medium to line sand. Total thickness of these older lake sediments is unknown.

Information on the subsurface lithology of Owens Lake sediments is limited to a few core logs from the lake center, margins, and upper basin. A well was

drilled by Southern Pacific Railroad at Lone Pine Station (Plate 1), about one mile northeast of Lone Pine (Lee, 1912). The well was drilled to 823 feet and

ed with 8.3 feet of stove pipe. Water was encountered at 52 feet and no strong artesian pressures were found at 823 feet.

The log consists predominantly of "quicksand" with interbedded and mixed gravel, sand, and clay. Presumably, the distinction between quicksand and sand

'S baSCd 01 the degreC °f SOTti“S “ d - e since the log description discriminates between "quicksand packed hard", "quicksand cemented", "sand medium coarse", coarse sand", and "clean sand medium grained". Blue clay layers are described as being tough" in the lower half of the core.

Another deep hole was drilled by the USGS in the south central part of the lake, about four miles north of Dirty Socks (Smith and Pratt, 1957). The hole was cored to 920 feet with 66 percent recovery.

The first three feet consists of irregular sandy trona crusts. The next two feet consists of gaylussite and some clay.

From eight to about 750 feet, the core consists of mostly massive, yellow- gray clay with lesser amounts of greenish-yellow, gray-green, and pale olive clay. Diatoms and ostracods occur throughout this section and are locally abundant to absent. Mollusk shells and a fish scale were also found. 22

he most interesting findings in the monotonous clay section are the frag ments and mottling at various depths as follows:

1. At 300 feet a one inch angular fragment of dark limestone was found.

mottled vellow-gray clay was cored with streaks of dark yel- g e . Mottled olive gray and medium brown clay were also found at 358.6 feet with fine sand. The sand consisted of two thirds quartz and feldspar and one third hematite and limonite.

3- At 407.8 feet a two inch thick core of green gray limestone was recovered It

18 Unka°™ if this is fr°“ - large rock or a limestone bed.

^ 4M 8 ° De b*d “ 30 percent g.ass with ciay, amphiboles and quartz. At 467.6 feet a one quarter inch bed of glass was found.

The remainder of the core, 750 to 920 feet, is mostly sand and silt with mterbedded Cay. Smith and Pratt do not describe the mineralogy of the sand except for those with volcanic giass at 756.2 feet and 767.3 feet. Sand and slit

generally massive and poorly consolidated. Coarser layem of coarse to m e d i u m sand are well sorted in few sections. Most layers are clayey silt and sands and yellow-gray silty Cays. Graded bedding is very pronounced

hroughout this section. Most iayers show a fining upward sequence of medium to coarse sand grading up to fine sand and clay. Few layers show a coarsening upward sequence.

Droste (1961) analyzed the core of Smith and Pratt (1957) for its clay con- The ratios of clay minerals from sediments entering Owens Lake were 2-7-1 montmoriHonite: i,liter chlorite and/or kaolinite. Variations in the proportion of c ays were due to amounts of montmoriHonite and chlorite. Increases in the amount of montmoriHonite were due to volcanic activity in Owens Valley during the Quaternary. 23

, J r° St detal'ed te 'riPti0n °f al°nE kke is by ' T (193!). Several boles were drilled and angered west of the Pittsburgh ate Glass (PPG) evaporation ponds to about 30 feet. PPG placed two to three

are soft to shghtly firm, moderately plastic, massive, generally homogeneous, and

''° ht t0 m° derately stron8 “dor of hydrogen sulfide. Only one of the holes contained a thin sand layer within the clay layer.

Soil tests were conducted on the clay layer to determine its engineering pro perties. Results are as follows:

1. plasticity index 11 to 23 (medium);

2. moisture content 50.9 to 57.8 percent;

3- permeability 0.3 feet per year for undisturbed clay; 0.06 feet per year for remolded clay; and

4. density (dry weight) 65 to 70 lbs. per cubic foot

Descriptions are less detailed for wells at Keeier, Olancha, and Cabin Bar (Plate 1). The Keeler well was drilled in 1902 to a depth of 465 feet (Lee 1906). Seven gravel layers were found, but no mention of their depth is made or type of sediments separating them lee nonfi') + , g 6 ^1906J reP°rts another well was drilled at Olancha to 80 feet through •'granitic wash" and sand. Four we,is on Cabin Bar

R - c h were drilled 186 to 300 feet (Perrine and Birman, 1982). Sediments encountered were interbedded clay, sand, and gravel.

S alt C rust

Precipitation of the salt crust from the dessication of Owens Lake was com-

M 1921

Trona was the first mineral to reach saturation by evaporative concentration of the shrinking lake. Pure trona was deposited over the entire iake bed below

until the lake elevation was 3 560 feet At tv * , , u At thls stage> virtually all bicarbonate a een precipitated with trona. Burkeite and halite coprecipitated from 3,560 to 3,553.4 feet. The residual interstitia. brines in the saline crust contained potash, potassium chloride, and borax.

A recent study of the salt crust at Owens Lake has been done by Saint- Amand and others (1986). This study focused on the reiation between salt crust c emistry, meteoroiogy, and hydrologic influences on wind lofted salts from Owens Lake bed. The authors conclude that dust storms are produced bv the

hydration/dehydration of sodium suifat. and carbonates. Decreasing tempera tures and rainfall in the winter produced hydrated forms of these salts. Increased volumes of salts are accompanied by the hydration. These salts break down into

1 ‘OOSe’ POWdery aEgreEate UPOn “ N a tio n . The loose powder can be blown away by winds in excess of 15 knots.

Upper Valley Lake Deposits

Deposits from Owens Lake extend as far as ten miles north of Lone Pine Paktser et ah, 1964). East of Big Pine, in Waucoba Canyon, are lacustrine depo-

S'tS C°nSidered *° ^ yOU”ger tha“ the C“ ° Formation. The sediments consist of Whtte to hght grey sandstone, shale, conglomerate, limestone, arkosic "grit", and fresh water gastropods. 25

unconsohdated sandstone, shale, and diatomite with fresh water fauna. It is partly covered by basalt flows and is considered Pleistocene (Pakiser et ah, 1064).

East of Independence, along the flanks of the Inyo Mountains, are crudely edded limestone, chert and quartzite. Th«e may also be of lacustrine origin Southeast of Independence, the Owens River cuts 20 feet into horizontally bedded aah gray sdt and fine sands. These beach deposits consist of long narrow bands of well sorted, cross bedded sands and gravels.

HYDROLOGY AND HYDROCHEMISTRY OF OWENS LAKE BASIN

PREVIOUS STUDIES

The hydrology of Owens Valley is unique to the Basin and Range Province because of the large amount of water that drains from the eastern Sierra Nevada untams. This large supply of water was tapped in 1913 when LADWP com pleted its aqueduct, diverting water to the growing population in Southern Cali fornia. Prior to the diversion, all water within the valley flowed towards Owens Lake. The lake dried when its water supply was cut off. Only during wet years when the capacity of the aqueduct is exceeded is Owens lake occupied by an extensive water body.

Currently, an average of 485.000 acre-feet per year of water flows out of Owens Valley through Haiwee Reservoir (Hutchison, 1986a). Total outflow from Owens Valley is the combined sum of Owens River inflow from Pleasant Valley mounts,n runoff, and groundwater pumping. The majority is supplied by surface water inflow to the basin. The most comprehensive hydrologic work in the Owens Lake area was by Lee (1915). 26 T T ? — - - °~ - ~ « ii— “ ' “ I P"1”' “»l « « l~l - (MDOT,

Mountain Hydrology

The Sierra Nevada receives the great majority of precipitation. Major creeks

creeks and percoiates into tractor, in higher eievations. This mountain recharge

Cnter thE Cr6ekS ^ l0Wer ele™tio“ basefiow to the perennial creeks or may d.scharge directly into the groundwater basin.

The Inyo and Coso Mountains receive much less precipitation than the ■erra Nevada. Intermittent creeks how only after storm events. Occasionally, eavy snow may accumulate in the higher elevations. These storms were large enough to stop operations at the Cerro Gordo Mine (Merriam, 1963). Mountain rec arge mto fractures at higher elevations is indicated by the springs north of erro Gordo Peak and east of Joshua Flat in the Coso Mountains. M ountain Runoff

Previous work on quantifying surface runoff from the Sierra Nevada along Owens Lake was done by Lee (1915) for Braiey, Cartago, and Oiancha Creeks

ee est,mated mean annual runoff from these creeks by using the nine year ga*ed ow at Ash Creek. Mean runoff for Ash Creek from 1904 to 1912 was 0.38 cubic <*t per second per square mile with a standard deviation of 0.22. Lee used a nservative value of 0.3 cfs per square mile for the ungaged creeks along the erra Nevada. Total runoff from Braiey, Cartago, and Oiancha creeks was estimated at 4,175 acre feet. LADWP has tv, • , , as gaced the major creeks (Cottonwood, raley, Ash, Lubkin, and Carol Creeks) since 1935. 27 Perrme and Birman (1Ma) attempted * ^ runoff to ^

7 " " PPI" °f Cab“ ^ RanCh at Cart^ - ^ey used the drainage “ °n " ^ <1912) * ^reek. Each drainage Cass is character e d by a particular runoff vaiue per square mile of drainage basin area above the alluvial fans. Perrine anH i Birman used a, valueaiue oiof 0 U.U3 qq nfc cfs per square mile approximately three times the vaiue determined by Lee (1915) from Ash Creek. ’

Runoff from ungaged eastern mountains is usually assumed negligible in companson to that from the Sierra Nevada. LADWP (1976) has made the only

quantify runoff from these sources. LADWP estimated 61,700 acre- Ret of runoff from ungaged ^ for the M ter ^ Qf ^ ^ on]y

5,100 acre-feet (8 percent) was assumed to reach the lake.

Basin Hydrology

Four sources contribute inflow to the Owens Lake basin: precipitation, uens iver, mountain runoff and recharge, and subsurface flow from the upper Owens Vaiiey and Centennial Flat. Most of these components have been quantified for only specific areas within the !ake basin or for specific times. Precipitation

Precipitation on the basin fill sediments has been quantified by Lee (1915) and LADWP (1972). Lees' estimate was only for precipitation on the lake surface ■u 1912. Lee used the mean annual precipitation of 3.15 inches at Keeler and a lahe surface area of 61,000 acres for his estimate of 16,000 acre-feet per year on the lake.

LADWP (1972) constructed an isohyetal map of Owens Valley from their Precipitation stations iocated throughout the valiey. Totai inflow to Owens Lake basin was not quantified from the map by LADWP. 28 Owens River

Mean annual inflow from O w ens R;,,0r n er Prior to the construction of the was 295,558 acre-feet (Ue, 1815) Comparab]e vo|umes ^

veeler Bridge have occurred only during extremely wet years since 1913

^ Saged ° " ” M w at Bridge since 1927. Hutchison (1986b) has studied baseflow to Owens River at Keeler Bridge. O w e n s L a k e

A graph of Owens Lake storage and surface area vs. lake elevation was pro duced by Lee (1916) when the lake was still filled with water. The area and capacity curves for Owens T ke are sho™ m Figure 10 and are referenced to USGS datum.

Evaporation

Evaporation from Owens Lake before and just after construction of the aqueduct was estimated by Lee (19,6). Lee computed the total infiow (except precipitation), outflow, and storage change for the nine year period 1906 to 1914

From this, Lee estimated an average annual evaporation rate of 4.81 feet from

Owens Lake. Net annual evaporation, including precipitation measured at Iveeler, w>as 5.07 feet.

This compares with the 5.58 feet of evaporation per year from Owens River near Independence (Lee, 1915). The decrease in evaporation at Owens Lake is due to the higher salinity and lower vapor pressure of the saline water. Lee (1915) describes the results of several experiments relating evaporation to salinity, meas ured by the specific gravity of the solutions. Results of the experiment are shown

“ FigUre “ • The S”dd“ “ evaporation is from the formation of a crust at a specific gravity of 1.27. The second curve in Figure 11 shows results when the crust is not allowed to form. Elevation (U.S.G.S.) ■ 3,650 •3,668 -3,570 3,662 3,666 j IO CD o O O ______IUE 0 OesLk raCpct Cre (fe AW, 1976) (afterLADWP, Curves Area-Capacity Lake Owens 10. FIGURE ) V cm o 1 o o " — i 40,000 ------__ t " 00 o o o , L

60,000 . - 000‘08 - T o o o o O -

120,000- oue ace-eet) e -fe cre (a Volume ra aces) cre (a Area

140,000 -

160,000 -

180,000-

200,000 -

220,000- CM o o o O ”

280,000 O C to percent rate of evaporation from brine to fresh water F GR 1. ecn Rt f vprto a Seii rvt (fe e, 1915). (afterLee, Gravity Specific va. Evaporation of Rate 11. Percent IGURE 31 Figure 11 indicates a decrease of 11 percent in percent in the evaporation rate for a specific gravity of 1.11 At th* , T , time of Lees estimate (1906-1914), the specific gravity of Owens Lake was 1 17 to 1 ns Not i • Net annual evaporation is 9 percent less than that from fresh water measured at Independence Th' j.independence, this agrees very well with the experimental data.

The only estimate of evaporation from Owens Lake bed sinee the lake dried

™ ^ B“ kS (1960)' «*>■“ *« "Eludes evaporation from the capillan. frmge and flooding of small areas of the basin. The estimation method is not desenbed, but Banks obtained a value 25,000 acre-feet per year.

The water budget for 1968-68 by LADWP (1976) was oniy for the water body of Owens Lake and considered only surface water evaporation. To compute total evaporation for the study period, data from an evaporation pan at Haiwee Reservorr were used without correcting for the higher salinity of Owens Lake.

Monthly evaporation rates for the pan were multiplied by a pan coefficient of 0 8 to obtain evaporation rates used in the estimate. Total corrected evaporation for the water year 1968-69 was 3.98 feet.

Evapotranspiration

Evapotranspiration from vegetated areas surrounding Owens Lake has never been quantified. Groeneveld et al. (1888) has studied plant water requirements of different vegetation in the upper Owens Valley. This study extended to the northwest corner of Owens Lake. Groeneveld (personal communication, 1887) also identified phreatophytes around Owens Lake and their water requirements. He indicates salt grass transpires about 40 inches per year and occurs in standing ,

-a te r near the toe of alluvial fans. Stands of willows and cottonwoods occur along the Owens River delta and CartagceOlancha area, respectively, and require three feet of water per year. 32 Groundwater Recharge

Mountain runoff occurs as streamflow across the alluvial fans and recharges the groundwater as it flows toward the lake. Previous workers in the area have not directly quantified the amount of runoff percolating into the fans adjacent to Owens Lake. Lee (1912) determined that 35 to 50 percent of total runoff from the Srerra Nevada recharges groundwater aquifers in the Independence area. Hutchrson (1086a) calculated recharge as a residual for the entire Owens Valley for the period 1071 to 1086. Fourty six percent of total runoff percolates into alluvial fans from this basin wide average. Water from the Sierra Nevada that

does not recharge the groundwater is diverted into the aqueduct and exported from the valley or spills over the aqueduct and flows toward Owens Lake. Water

from the Inyo and Coso Mountains that does not recharge the groundwater flows into Owens Lake.

Groundwater Discharge

Groundwater discharge occurs by spring flow along the lake margin, evapo transpiration, and pumped and flowing wells. Cottonwood Springs, at the west margin of Owens Lake, is the largest single spring discharging into Owens Lake. LADWP (19/6) reports total discharge for 1968-69 at 1,700 acre-feet.

The Cartago-Olancha area is the largest spring discharge zone. Total discharge is from combined recharge on the Olancha and Cartago Creek fans Perrine and Birman (1982) report that most springs on Cabin Bar Ranch occur along a northwest trending fault scarp. Total discharge of springs on the ranch is about 1.300 acre-feet per year.

No direct measurements have been made on spring discharge along the south and east Owens Lake margin. Lee (1915) assumed that total discharge from these springs equals one half the runoff from Braley, Cartago, and Olancha Creeks, 33

Which he estimated to be 2,095 acrerfeet. Lee did not comment on how much

runoff and percent recharge aiong the Inyo and Coso Mountain fronts would be lequired to sustain this amount.

Many wells are located throughout the Owens Lake basin. Most wells were drilled in the early 1900's into artesian apuifem and remain Sowing today. Very

few records for the wells have been found. The earliest well record (Lee, 1906) is of the well at Keeler. The well penetrated seven gravel layers, all with strong artesian pressure. The first flowing conditions were encountered at 85 feet. The upper 190 feet of the well were cased with six inch pipe. Inside this, a four inch

casing was extended the entire depth of the well. Neither casing was perforated and water was allowed to flow into the bottom of the pipe. Water entering the outer casing at 190 feet had a head 20 feet above ground surface and was high in

dissolved solids. Water at 465 feet was "comparatively free" of dissolved solids w.th a head of 35 feet above ground surface. Total flow from the well was 550

gpm. Both horizons yielded natural gas at one cfs. The test hole drilled in Olan- cha m 1902 (Lee, 1906) did not encounter flowing conditions.

Four wells on Cabin Bar Ranch were drilled into interbedded clays, sands, and gravels to a depth of 186 to 300 feet (Perrine and Birman, 1982). All wells were flowing at time of drilling. The wells were pump tested twice to the installed pump capacity without apparent change in the potentiometric surface (JMLORD, 1984). The pump capacity is not noted. Total well production is about 100 gpm or 150 acre-feet per year.

Perrine (1983) conducted a ground temperature survey of the Cabin Bar Ranch to delineate areas of groundwater flow. Most of the groundwater is less than 10 feet deep east of Highway 395. Results of the survey indicate that groundwater flow's due east, approximately perpendicular to the northwest 34 trending fault scarp. The fau,t appears tQ ^ ^ ^ ^ ^ ^ ^ ^ ^

ern part of the ranch where groundwater rises along the fault and discharges

front springs. In the northwest part of the ranch, the fault either dies out or is not an effective barrier to flow tv,q t u how. The fault scarp west of Highway 385 does not appear to act as a groundwater barrier.

L.UtW'P (1972) constructed an isopotential map from their wells located throughout the valley. Ve,y few wells exist along the eastern half of the valley

and northern Owens Lake. This map should only be considered a very rough estimate of the potentiometric surface.

Closed Basin Sedimentology

Sedimentology of closed basins consists of several different environments. Primary influence on all subenvironments is the nature of inflow to the closed basin. Subenvironments of saline lakes include the following: 1) alluvial fans; 2) sandflat; 3) mndflat; 4) ephemeral saline lake; 5) perennial saline lake; 6) dune field; 7) perennial stream flood plain; 8) ephemeral stream floodplain; 9) springs-

end 10) shoreline features (Hardie, Smoot, and Eugster, 1978). All environments may not exist in each closed basin. A hypothetical closed basin with the subenvironments is shown in Figure 12.

Alluvial Fans

Alluvial fan sedimentation around the perimeter of Owens Lake is the result of drainage basin erosion of the uplifted mountains. The fans’ role in basin hydrostratigraphy is two-fold. Exposed fans are recharge zones for aquifers and buried fans conduct water into the lake sediments.

Fan deposits can be divided into two types: I) debris flow; and 2) streamflow deposits. In general, the fan is wedge shaped with grain size and bed thickness

decreasing downfan and ronndness and bedding structure increasing downfan (Walker, 1984).

Dry M udflats

An exposed, fine grained sediment plain bordering saline lakes is termed the dry mudflat subenvironment (Hardie, Smoot, and Eugster, 1978). Dry mudflats are differentiated from saline mudflats by less salt growth and disruption of sedimentary structures.

Dry mudflats are characterized by dessication polygons and thin salt crusts. Two kinds of crust have been identified: 1) thin, hard alkaline earth carbonates; and 2) pufiy, porous crusts, several centimeters thick, composed of soluble salts (Hardie, Smoot, and Eugster, 1978).

Crusts form through the evaporation of brines drawn up through capillar action. Thin, carbonaceous crust typically forms near the outer edge of the

mudflat where brines are diluted from inflowing water. Soluble salts precipitate where brines have evolved into a more concentrated stage.

Ephemeral Saline Lakes

Ephemeral saline lake subenvironments are characterized by shallow, concen trated brines that completely evaporate eveiy few yearn, forming salt layers. Inflow to these lakes is mostly from periodic runoff from large storms and margi

nal springs which dilute the brines. After each storm, evaporation reduces the lake level and brine concentration increases. This cycle produces two subenviron ments of ephemeral saline lakes: 1) a salt pan of bedded, soluble salts in the lowest part of the closed basin; and 2) a saline mudflat consisting of muddy das- tics and salts peripheral to the salt pan. 37 Perennial Saline Lakes

_ PereDnial SaM"e ‘akeS are iakes which of years without completely drying. Large amounts of perennial streamflow are required to maintain a water body. Inflow transports solutes and elastics in addition to supplying water to the lake. Evaporation of the lake leads to a sequence of brine concentration, salt cy- stallization, and crystal settling (Hardie, Smoot, and Eugster, 1078). Dune Fields

Flat topography, sparse vegetation, dry climate, and fine sediments from sand and mud flats provide the setting needed for wind erosion and deposition in

closed basins. Wind deposits are of relative insignificance in the basin hydrostratigraphy.

Perennial Stream Floodplain

Inflow to perennial lakes is usually by one or more major streams. Deposi tion of sediments from these streams forms deltaic bedforms which are similar to alluvial fans, but deposited subaqueously. Deltaic sedimentary environments are most easily divided into subaerial and subaqueous zones (see Figure 13). Subaerial deposits consist of braided channel and meandering channel deposits -

the stream floodplain of Hardie, Smoot, and Eugster (1978). Subaqueous deposi tion from rivers discharging into lakes is comprised of lacustrine delta fill. S p r i n g s

Springs typically form in areas along faults at fan apices, playa margins, within playas, and at the contact between porous and relatively impermeable sed iments where fans overlie muds (Hardie, Smoot, and Eugster, 1978). Although springs are minor features, they supply perennial flow of water and solutes to the playa and are areas of chemical and biochemical sedimentation. 38

FIGURE 13. Components of a Delta System (after Coleman and Prior, 1982). 39 Shoreline Features

Shoreline features include beach ridges, spits, bars and platforms, and mound buildups. Most form in large, perennial lakes with high energy such as currents and wave action.

Playa Surface Morphology

Much work has been done on playa surfaces by the Air Force in their efforts to find large, flat surfaces that can support heavy aircraft. These studies on

many of the play as in the Mojave desert have identified several crustal types. Playa crust morphology is a direct reflection of the hydrologic conditions influencing the playa. Factors controlling crustal types are; sediment size and

texture, depth to groundwater, rate of capillary discharge, and frequency of sur face flooding (Cook and Warren, 1973).

Classification

Playa surface morphology has been classified based on depth to groundwater and types of groundwater discharge (Cook and Warren, 1973). Each category is not mutually exclusive since the nature of groundwater discharge is variable within each playa. Caution must be used in interpreting playa morphology since different hydrologic processes can produce similar surfaces.

This classification of surface morphology consists of six different categories:

1. Total Surface Water Discharging Play as: these playas are characterized by smooth, hard surfaces of silt and clay and are usually dry. Water tables are rela tively deep. These hard surfaces are fairly impermeable and a downward

hydraulic gradient develops when flooded. These playas have a high frequency of surface floods. 40

Clay fraction of sediments is greater than 50 percent. Average carbonate and soluble salt content is 7 percent and 5 percent, respectively (Langer and Kerr, 1966).

2. Capillary Discharging Surfaces: these surfaces are associated with soft, puffy ground that becomes "crusty" in summer. Thickness of salt crust is directly pro portional to the rate of capillary discharge. Generally, salt crusts are soft, fairly permeable and loosely compacted with a high infiltration capacity. Clay comprises less than 35 percent of the sediments and the average carbonate and soluble saline contents are 2 percent and greater than 5 percent, respectively (Langer and Iverr, 1966). The capillary fringe is generally shallow, except in sum mer when evaporation may lower the water table and dry the upper surface.

3. Direct Groundwater Discharge: these surfaces are characterized by thin salt crust or thick salt pavement (46 cm.) in areas of seasonal or perennial groundwa ter discharge. Surfaces are wet, soft, sticky, and puffy in places.

4. Phreatophyte Discharge: groundwater loss by evapotranspiration occurs in areas with shallow water tables and low salinity. Surfaces are distinguished by ring fissures, slight surface subsidence, and phreatophyte mounds.

5. Spring Discharge: these surfaces occur where the water table or hydraulic head is higher than the playa surface. Cook and Warren (1973) do not discuss the difference between this category and category 3.

6. Combined Surfaces

Several of the above surface types may occur at a playa. Gradations between surface types may suggest changes in clay content, salt content, surface moisture, or depth to groundwater. 41 Morphologic Changes

Crust morphology changes readily in response to seasonal and long term climatic changes, which controls the amount of surface and groundwater discharging onto or from the playa surface. Motts (1970) has reported observa tions at several Mojave playas on seasonal and yearly changes in surface crusts.

Lowered water table and potentiometric surface elevations at Harper, Lucerne, Rogers, Rosemond, and Troy playas have directly resulted in changes in playa crusts (Motts, 1970). In the early 1900s’, Rogers and Rosemond playas had

puff} surfaces when the potentiometric surface was high. In the 1960s’, the potentiometric surface had dropped to where capillary discharge could not affect the surface. Flooding of the dry lakes has changed their surfaces into smooth, hard ground. At Harper dry lake, surfaces changed from being soft, dry and fri able in 1962 to a hard dry surface in 1967.

At Troy playa, in southeast Mojave, heavy pumping of an aquifer along the west side of the playa decreased the water table throughout the valley. Induced gradients from pumping resulted in intrusion of poor quality water from the playa into the fresh water aquifer. Declining water tables resulted in decreased capillary discharge. Depth to water was 10 to 15 feet below the playa surface. Surface crust morphology depended on the sediment type in which the water

table existed. Most of Troy playa is covered with puffy crusts. In clays, capillary fringes were pronounced and produced puffy surfaces from groundwater evapora tion. m e r e the water table existed in sand layers, the surface was hard and dry. Combined effects of lower capillary discharge, compaction by flooding, and dessication converted puffy surfaces into hard surfaces.

Fluctuations in lake level and surface flooding washes and compacts crusts into a hard surface (Motts, 1970). Even playas which have a high rate of 42

capillary discharge may have smooth surfaces if flooding frequency is enough to wash salts from the surface. Effects of surface flooding are exemplified by the changes at South Panamint playa in 1966. Ballarat Road, which crosses the playa, acted as a dam and restricted water to one half of the playa. Flood waters consolidated the puffy surface into smooth, hard ground able to support

trucks. By the winter of 1967-68, the hard ground had converted back to its former moist, puffy condition.

HYDROSTRATIGRAPHY

The hydrostratigraphic model of Owens Lake focuses on the upper 3,000 to 4.000 feet of sediments. It is assumed the fault block in the middle of Owens

Lake restricts circulation of waters from deeper portions to the surface because of the relatively impermeable basement rock. Distribution of sediments in the upper 3.000 to 4,000 feet of valley fill is constructed from the surface morphology, core logs, spring and well chemistry and isotopes, and correlation with Searles Lake paleochmatology. This model overly simplifies the stratigraphy of the valley fill and facies relationships. Plate 2 is a fence diagram of the distribution of sedi ments m Owens Lake basin. The diagram is oriented with a southwesterly view from the Cerro Gordo area. Cross section lines are shown on Plate 3.

Owens River

Delta Region

Surface morphology is the best indicator of the extent of depositional sys tems in the Owens Lake basin. The Owens River delta is the most extensive source of sediments capable of yielding and storing large volumes of water. The Owens River delta prograded at least nine miles south of where the river crosses 43

the hydrographic divide. Two types of delta morphology can be seen in the false color infrared photograph (LADWP, 1977): 1) homopycnal (density of inflowing water equals density of receiving water) delta morphology within the beach ridge located at approximately 3,555 feet elevation; and 2) hypopycnal (density of inflowing water is less than density of receiving water) delta morphology between the hydrographic divide and the beach ridge.

Delta lobes within the beach ridge are about one mile wide with steep, well formed foresets, indicating deposition in fresh water. There are two main lobes within the beach ridge. The delta lobe furthest south bends southwest, parallel the beach ridge. This suggests the delta formed in a lake within the beach ridge and the topographic low was in the western half of the lake. Approxi mately one half of the southern delta lobe is overlain by a more recent lobe. A

dark, wide, elongate area surrounds both lobes and extends approximately two miles south of the beach ridge.

The preserved morphology of the older delta lobe and the sharp contact between it and the overlying lobe indicates the lake margin migrated north rapidly. Otherwise, the interior of the older delta lobe would have been filled with fine sediments by a gradual migration and the contact between the two lobes would be less distinct. This could result from the lake level exceeding the elevation of the beach ridge. A small increase in lake elevation above the beach ridge could significantly increase the lake surface area over a flat surface. This is suggested by the darkened area extending south of the beach ridge. As the lake elevation increased, dilute waters (<1,000 ppm) may have dissolved salts on the playa surface, increasing lake salinity. Sediments discharging into the lake 44

would be dispersed over a wide area as the lake salinity and elevation increased. The rapid increase in lake elevation and increasing salinity is also indicated by the abrupt end of homopycnal delta morphology at the north beach ridge.

The hvpopycnal delta formed by the most recent lake extends from the hydrographic divide to the beach ridge. Sediments are dispersed over an area approximately five miles south by three miles east-west, forming a single, wide delta lobe.

From the morphology of the delta region, it is likely a shallow aquifer extends approximately nine miles into the middle of Owens Lake and is about one mile wide. Aquifer tickness is indeterminable, but the extent of the delta suggests significant (> 10 feet) amounts of sediments were deposited. The aquifer consists of fine to medium, well sorted sands of point bar deposits. The core log at Lone Pine Station (Lee, 1915) indicates point bar deposits in the lower

Owens Valley are no coarser than coarse sands. Within the beach ridge, these deposits are probably covered by silts, clay, and salt of unknown thickness. Between the hydrographic divide and the beach ridge, the aquifer is overlain by fine sands of the hypopycnal delta, observed by Westec (1984).

Aquifer extent and width at greater depth in the delta region would depend on past lake elevation and salinity. The core log at Lone Pine Station indicates extensive lake deposits do not occur for the first 125 feet and make up a small

(<10 percent) proportion of the 832 feet of the log. Presence of fine sands at the hypopycnal delta lobe indicates lake elevations must be considerably higher for lake sediments to be deposited at Lone Pine Station. It is suggested that the delta region, within five miles of the hydrographic divide, consists of a multilayer, confined aquifer of fine to medium sands. It is possible sands make up at least 50 percent of the stratigraphic column for 3,000 to 4,000 feet in this area. Aquifers extending far into Owens Lake like the shallow aquifer would require the near desiccation of Owens Lake for the delta to prograde onto the lake bed or an open basin. Paleoclimatology of the region indicates the frequency of dry hydrologic regimes would make sand deposits greater than five miles from the hydrographic divide uncommon and a small proportion of the stratigraphy in the center of Owens Lake.

Channel Deposits

The hole drilled by the USGS (Smith and Pratt, 1957) was located on or just south of the beach ridge in the south central portion of the lake. It is difficult to determine if the homopycnal delta influenced the sedimentology this far south because the first 40 feet of lake sediments were not recovered. Recovered core to 750 feet consists of mud and silt, indicating delta sediments did not reach that far south in the upper 750 feet.

In the USGS hole from 750 to 920 feet, the core log consists of graded, very fine to coarse sands with layers one to six feet thick. Clay and clayey silt layers two to four feet thick are interbedded with the sands. This sequence is typical of meandering point bar deposits. The thickness of sediments (170+ feet) suggests that the Owens River flowed south to the Olancha area for an extended period. This could be because the topographic low was located in the southern portion of the basin and Owens River flowed into a much smaller lake.

More likely, the Owens River flowed out of the Owens Lake basin through Haiwee Pass to China Lake basin. A plausible explanation is that Owens Lake had overflowed the basin, eroding the escarpment that had closed the basin. The Owens River flowed through the basin and continued to erode the escarpment at a rate greater than offset along the fault. An extensive, thick aquifer of clean, 46

well sorted sand would exist in the center of the basin from the upper valley to Haiwee Reservoir. Eventually, the faulting rate surpassed erosion and closed the basm. The basin became occupied by perennial and ephemeral lakes for the duration of its history. Depth to this aquifer would be greatest in the center of the basm which has been downdropped relative to the mountains and is the site of greatest deposition in the closed basin. It is unlikely these types of aquifers are common in the remaining 2,000 to 3,000 feet of the center of the basin.

Alluvial Fans

Other surface features which indicate the presence of coarse sediments within the 3,600 feet elevation contour are the alluvial fans at Cottonwood Creek, Lake

Minerals, and Centennial Flat. Extensions of these fans can be seen on true color aerial (LADWP, 1986) and false color infrared aerial photographs. Both the Cot

tonwood and Centennial Flat alluvial fans prograded about two miles onto the lake and are about 1.5 miles from the USGS hole. These fans have the largest drainage area m Owens Lake basin. The fan at Lake Minerals extends about one mile onto the lake bed and is smaller than the other two. Lack of alluvial sedi ments in the USGS hole suggests the fans did not prograde much further in the past.

The morphology of the Cottonwood and Lake Minerals alluvial fans is different than the Centennial Flat alluvial fan. The former fans have a coarser texture, appear thicker, and have been modified by waves with well formed beach ridges. Sediments of the Centennial Flat fan appear more dispersed and can be seen only on the infrared photograph. 47

Alluvial fans must have prograded onto the lake bed when it was virtually dry to extend two miles onto the lake bed. Alluvial fans probably prograded

simultaneously with the homopycnal delta lobes to the center of the lake. The convergence of the fans and delta lobes near the USGS hole indicates the topo graphic low during this dry period was in this area.

No evidence of other fans that may have prograded far into Owens Lake can be seen on the infrared and aerial photographs. This could be due to deposition of fine sediments, dunes, and salt precipitation over the alluvium or simply the lack of significant alluvium deposits from other drainages during the recent dry regime. Well logs from Keeler, Olancha, Cartago, and PPG document alluvial fans from lesser drainages prograded at least to the lake margin. Coarse sands and gravels encountered in these wells are most likely from the mid to lower allu

vial fan environments. Lower alluvial fan and sandfiat environments, consisting of medium and coarse sands, may extend much further than the lake margin at various depths.

Extent of the lower alluvial fan and sandfiat environments can be estimated bv comparing Coso alluvial fans to Inyo alluvial fans. Both areas have similar morphology, indicating similar grain size distributions. Inyo alluvial fans in the Keeler area are steeper, truncated by a fault scarp at approximately the same position of the fan as the Coso Mountains, and have a much larger sediment source area. Inyo alluvial fans should prograde at least as far as Coso alluvial fans assuming they are allowed to prograde unhindered by a lake.

The intersection point of the Coso alluvial fans is approximately at the fault scarp. The intersection point of the Inyo alluvial fans is at or below the fault scarp. Therefore, the sandfiat and lower fan environments, which form below the intersection point, should extend approximately the same distance from each 48

fault scarp. Sandflats form a one to two mile wide zone along the Coso Moun

tains. Assuming a distance of two miles, the sandflat environment of the Inyo alluvial fans should extend at least one to two miles into Owens lake.

Owens Lake margin can be characterized by multilayer, confined aquifers separated by lake deposits. Surface morphology and well logs indicate the mar gin consists of wedges of gravel and coarse sand that thin and grade laterally into

medium and coarse sands. These alluvial fan deposits would have a relatively high continuity parallel to the lake margin. Continuity perpendicular to the lake margin would be controlled by the duration of perennial and ephemeral lakes. Deposits may have been reworked by waves at high lake levels, winnowing out fine sediments. This sorting would greatly improve the hydraulic properties of the deposits. Without deep well logs along the lake margin, it is assumed the vertical extent of alluvial fans is continuous to 3,000 to 4,000 feet. The most significant of these aquifers are most likely along the base of Cottonwood Creek alluvial fan, the northeast lake margin, and possibly Centennial Flat alluvial fan.

V olcanics

'Volcanics interbedded with the Coso Fm. may also act as aquifers. The youngest dated volcanics formed approximately 2.5 m.y. ago, about one half the age of the oldest sediments in the basin. This suggests that volcanics are at a great depth within the 3,600 feet elevation contour. Volcanics may be at shallow

depth along the flanks of the upthrown mountain blocks. Gravity profiles of the basin indicate these shallow areas are within three to four miles of the basement rock-valley fill contact. Concentration of surficial volcanics in the Coso and southern Inyo Mountains suggests volcanic aquifers most likely occur in these areas and in Centennial Flat. 49 L ake C lays

Lake clays at the experiment site readily yield water, indicating clay permea bility is significant. This is consistent with work by Langer and Kerr (1066), who found that clays flocculated in saline water have higher permeability than clays flocculated in dilute water. A bailer test was conducted with the piezometers at the Salt Crust Experiment Site (SCE) (Cochran et al„ 1987) to determine hydraulic conductivity of the clays. Recovery time was analyzed by the method of Bouwer and Rice (1076). Hydraulic conductivity of the clays is approximately

10 5 cm/sec. This value falls in the range of hydraulic conductivity for silt, sandy silt, and clayey sands (Fetter, 1980).

Lake clay can be considered aquitards. Water is capable of being stored in and leaking from the clays into aquifers. At greater depth, clays may be less permeable due to compaction from lithostatic pressure.

Salt C rust

Core logs around the lake bed margin and the center of the lake bed do not record any salt layers at depth. The surface salt crust appears to be the only

evaporite deposit in the basin. This surface crust is described in detail in the later sections.

The salt crust was studied in detail at the SCE and is an important com ponent of the hydrostratigraphy because of its insulating ability. Soil moisture and temperature measurements at the SCE indicate the rind is an effective vapor barrier and reduces evaporation from the saturated clays.

A sand pit was dug at the SCE and backfilled with sand to monitor vertical movement of salts in the crust. Cores were periodically taken and the amount of soluble salts measured at 1.5 to 2.5 inch intervals. Results indicate that when 50

the salt crust is dry, evaporation concentrates salts at the capillary fringe. When the salt crust is moist, brines are capable of moving to the surface in the fluid state by capillary action. Evaporation occurs at the surface and solutes precipi tate a puffy crust.

Aquifer Continuity and Correlation

Core logs, water chemistry and isotope composition, and the location of wells provide information on the source of aquifer material, recharge areas, and extent of aquifers in Owens Lake basin. These data are confined to the upper 920 feet of sediments. Deeper aquifers must be inferred by estimating time of aquifer sediment deposition and assuming similar processes occurred during similar hydrologic regimes.

Correlation between two wells to determine aquifer continuity is confounded by the different sedimentation rates of various depositional environments and faulting that has dissected the aquifers. Sedimentation rates are based on Smith et al. (1983) work at Searles Lake. This allows for approximate dating of the aquifer sediments and the hydrologic regime in which they formed. Similar layers can be inferred at greater depth according to the sedimentation rates assumed. The following assumptions are made to reconstruct sediment deposition:

1. Approximately the same deposition rates occurred at Owens Lake as Searles Lake. Sedimentation rates of 15 to 20 inches per 1000 years are assigned to the central portion of the lake which is dominated by clay deposition. Sedi mentation rates of eight to 12 inches are assigned to lake margins where alluvial and lacustrine deposition occur.

2. Wells terminate in the middle of the aquifer and the estimated age is the mean age of deposition. 51

The USGS hole and Sulfate Plant well are located in approximately the same environment in Owens Lake with respect to distances from sediment sources along the lake margin. The biggest difference is their location with respect to the Owens River delta. The Sulfate Plant well is much closer to the delta and may be influenced by delta sedimentation.

Unfortunately, there is no drillers log available for this well and thus the sediment lithology and total depth are unknown. A down-hole video camera was

used m an attempt to determine total depth, locations of perforated zones and casing condition. At a depth of approximately 420 feet the hole significantly departs from vertical. At a depth of 463 feet the top of a broken drill stem was encountered. Because of the drill stem and crooked casing, the camera could not go further than approximately 475 feet. At that depth there was significant upwelling and circulation of fairly coarse sand. Possibly, the hole collapsed dur ing the drilling operation, trapping the drill bit and stem. The well casing was installed in 3 feet segments. No better estimate of well depth can be obtained because of the short segments used in well construction. Inflow conditions at 475 feet indicate a permeable zone (sands and gravel) below this level.

The well is believed to have been drilled sometime before 1930. The casing, however, was found to be in very good condition, showing only limited indica tions of either corrosion or encrustation. Perforations were found at three depths; 1) 225 to 227 feet, 2) 317 to 318 feet, and 3) 370 to 390 feet.

Assuming ranges of deposition rates of 15 to 20 inches per 1000 years, the Sulfate Plant well is tapping sediments deposited 290,000 to 380,000 years ago. The USGS hole consists of clay with few silt layers to about 750 feet. This depth 53

identical chemistry, except for the lack of sulfate. A hydrogen sulfide odor emits

from the Sulfate Plant well water indicating reducing conditions in the aquifer. The Sulfate Plant well video indicates that bubbles, probably composed of C 0 2 and H 2S , stream into the casing at approximately 6 feet depth. Wells and springs sampled along the northeast and east lake bed margin and the Sulfate Plant well may be end members of a trend in increasing reducing conditions toward the Sulfate Plant well. A trend in reducing conditions would expected if the flow path is from the east toward the lake. Dissolved oxygen and Eh meas urements need to be taken to establish the possible trend. The second trend is the loss of Ga (calcium ion) and M g (magnesium ion) from the well north of Keeler to the spring which is approximately 150 to 200 yards out on the lake bed. There is also a trend in increased N a + K (sodium and potassium ions ) and H C O s

(bicarbonate) to approximately the same concentrations as the Sulfate Plant well.

Both the Sulfate Plant well and spring contain virtually no sulfate and smell of hydrogen sulfide. Chemistry of the Keeler well (sample 5; Plate 4), which is on the fans above the spring, and sample 3 (Plate 4), could have evolved into the

Sulfate Plant well and spring chemistry by dissolution of sediments to increase N a + K and H C O s. Reduced Ca concentrations can occur by incongruent dissolu tion of dolomite.

Isotopes in water from the Sulfate Plant well are not very good indicators of the recharge source (Appendix 2). Isotopic composition indicates the water ori

ginates at high elevations from snow melt, possibly from the Sierra Nevada or Inyo Mountains. However, the Keeler well, which is most likely recharged from the Inyo Mountains, has about the same isotopic composition as Sierra Nevada water and the Sulfate Plant well. This makes it difficult to separate recharge source area based on isotopes. 54

Hydraulic head data in the area suggest that the Sulfate Plant well water originates from the Inyo Mountains. The well drilled in 1902 at Keeler (elevation 3,609 feet) had a head of 35 feet above ground surface at a depth of 465 feet. The combined head of the perforated zones at the Sulfate Plant well (elevation 3,559 feet) is at least 11 feet above ground surface. This is the expected gradient for flow towards the lake from the Inyo Mountains.

It is possible the heads at the Sulfate Plant well and lake margin are due to differences in water density and not because of potential energy and fluid pres sure. Specific gravity of the brines at the SCE is approximately 1.11. Water discharging from the Sulfate Well has a specific gravity of 1.0. The observed head could be due to the higher density of water overlying the aquifer. If the well is approximately 480 feet, and assuming a linear decrease in specific gravity, then the pressure exerted on the aquifer by the overlying column of brine should force the water approximately 25 feet above ground surface. This accounts for all the head measured at the Sulfate Plant well, suggesting the lake could be the source of recharge to the aquifer.

If density differences are the driving force at Owens Lake, then groundwater flow' directions v'ould be the reverse of the typical model of discharging playas. High density water overlying the center of the lake forces w'ater down and out to discharge along the lake margins. The lake would act more like a recharging playa, where water infiltrates into the lake sediments and recharges the groundwater. How'ever, if this w'ere the case at Ow'ens Lake, then the chemical composi tion of the Sulfate Plant w'ell would change over time due to the chemical gra dient. Also, the w'ater would be expected to have a heavier isotopic composition due to evaporation of the lake waters before infiltration into the lake sediments. Even in wetter hydrologic regimes, the lake waters would be evaporated and oo

would be expected to be heavier than current recharging waters. Water currently flowing from the Sulfate Plant well is of the same isotopic composition as recharging waters, indicating the source of the water is from the local mountains and not paleo-waters trapped in the sediments and being forced up by the overlying brine.

Chemical, hydraulic, and geologic evidence suggests that the Sulfate Plant well is hydraulically linked with the Inyo Mountains. The well could be ter minated in an extensive aquifer system deposited during hydrologic regime IV when alluvial fans where able to prograde several miles onto the lake bed. Based on uhe assumed marginal sedimentation rates, the old w'ell at Keeler terminates at an aquifer deposited 465,000 to 700,000 m.y. ago.

Dirty Socks well terminates at a depth of 595 feet, hitting an aquifer depo sited 595,000 to 890,000 years ago. These ranges fall within hydrologic regimes V

(intermediate) and IV and approximately coincide with the estimated age of the top o 1 the sands in the USGS hole. Estimated ages are consistent with the idea that major marginal aquifers were formed during dry periods and prograded into the basin unhindered by a lake. Deeper marginal aquifers may have formed coin cident with the sands of the USGS hole.

It is likely that Owens River remained near the center of the basin and did not meander to the margin. Streams flow along the paths of least resistance and erode sediments to obtain the lowest gradient. It is unlikely the river could meander along the margins of the fault bounded basin for any length of time because: l) alluvial fans create topographic highs along the basin margin. As the delta progrades into the basin, so do the alluvial fans. This would prohibit the Owens River from meandering along the lake margins; and 2) small amounts of offset along the basin faults could shift the course of the river significantly. The 56

center of the basin has been downdropped relative to the mountains, so the river would shift to the lowest point in the basin. This would result in the Owens River meandering back and forth in the center of the basin between the Inyo and Sierra Nevada Mountains.

The hydraulic link between the Inyo fans and the Sulfate Plant well may be disconnected by major faults along the basin mapped by Carver (1969) and Pakiser et al. (1964). Gravity profiles indicate faults approximately 1.5 miles northeast of Iveeler and 0.5 miles west of the Sulfate Plant well. The fault northeast of Iveeler probably has relatively little effect on groundwater flow because there are no thick, relatively impermeable sediments to be juxtaposed with alluvial sediments. The fault near the Sulfate Plant well could have a great effect on groundw'ater flow by juxtaposing lake sediments with alluvial fan sedi ments. If the fault plane is nearly vertical through the valley fill, as suggested by Carver (1969), then the hydraulic link between the Inyo Mountains and the Sul fate Plant well may not be disrupted. Depth to bedrock is approximately 5.000 to 7,000 feet at the fault. The fault plane must dip at least 25 to 30 degrees from the vertical through basin sediments to offset any sediments east of the Sul fate Plant well.

Based on the Smith et al. (1983) hydrologic regime classification, the 465 to 750 feet interval is the shallowest depth to major marginal aquifers. The only other dry hydrologic regime occurred approximately 2.56 m.y. ago. Assuming an average sedimentation rate of 10 inches per 1.000 years, these deposits would be at a depth of approximately 2,000 feet. 57

SURFACE MORPHOLOGY

Distribution of playa environments in Owens Lake provides indirect evidence of the hydrologic processes occurring in the basin. Owens Lake surface morphol ogy is the result of the grain size of shallow sediments and hydrology of the basin. Westec (1984) has described the distribution of sediments along the eastern and southern portions of the basin. Observations made during this study have provided more detailed information on crust morphology and mineralogy. With this ground control and the aerial photographs, the grain size distribution and hydrology can be interpreted from the surface morphology. Playa environ ments were mapped from aerial photographs and are shown on Plate 5.

S an d flats

The sandfiat environment of Owens Lake is prevalent along the north to southeast lake margin. The Owens River delta produces essentially the same type of environment as alluvial sheetfiood deposits with respect to crust morphol ogy and grain size distribution. The sandfiat environment along the northeast margin of the lake is approximately 2.5 miies wide from the Owens River delta to the Sulfate Plant well road. Shallow' sediments are described as fine to medium grained sands with finer sands near the delta (Westec, 1984). Sandflats have few' thin clay lenses in this region and are overlain by megaripples up to 6 inches thick w'est of Keeler. Sands are described as being moist, but not saturated.

Overlying the sands are salt crusts up to 1/8 inch thick with thin sheets of sand overlying the crust south of the megaripples.

Lack of a thick salt crust in the northeast quadrant of the lake bed appears to be the result of the coarse grained sediments derived from the delta and Inyo Mountains and surface floods that deposited the sands. Moist sands indicate the 58

water table is fairly shallow, but the capillary fringe is not pronounced because of the large capillaries of the sands. Evaporation creates upward gradients which may further enhance the fringe, wet the sands, and precipitate a thin salt crust at the surface. The thin salt crust could be due to the low volume of salt moved to the surface because of the depressed capillary fringe or wind blown salt that formed a crust on the moist sands. The thin crust is fragile and easily eroded. This brittle crust described by Westec. is similar to the crust observed on the sand pit at the SCE. Well sorted sands do not have fine sediments to form a matrix and increase the cementing strength of the salt.

Lack of well developed drainages along the northeast lake margin indicates no major perennial springs exist in this area (Plate 6). It is possible salts are washed from the sands by sheetfioods that deposited the sands. This is suggested by the salt crust observed in the aerial photographs between the delta and sandflats. This patch of salt crust is not in the flow path of Inyo Mountain runoff and forms undisturbed on the sands. Most likely, it is a combination of the coarse grained sediments depressing the capillary fringe, a brittle crust, and flooding that "washes the salts from the surface to produce a relatively salt free surface in the northeast portion of the Owens Lake bed.

S alt C rust

The sandflat environments described by Westec south of the Sulfate Plant road and along the southeast lake margin are characterized by compound crusts. Thin salt crusts form in channels with saturated sands separated by salt pave ments up to two feet thick, forming elevated "islands". The SCE was located on one of these salt pavements. Compound crusts are not unique to areas underlain by sands as suggested by Westec. Brown and black clay underlies the salt 59

pavement at the SCE and in the ponds near the Sulfate Plant well. The SCE is located in the area designated "Powder Aggregate Underlain by Wet Clay" by Westec. Observations made around the site in the summer of 1986 indicate the eastern contact should be moved approximately 0.5 miles west of the site.

Based on \\ estec observations, observation at the SCE , and aerial photo graphs, the surface crust and morphology of the southeast and south portions of Owens Lake bed are primarily the result of surface flooding. Grain size is evi dently not a factor in compound crust development. Large areas of compound crust are separated by mudflats and sandflats which probably have thin crusts similar to the sandflat environment to the northeast. Mudflats and sandflats have well developed drainages extending out from major springs and wells (Plate 7). For example, large areas of exposed muds occur on the south side of the Sul fate Plant well road where the tailings well and major spring drain.

"V ariations within a small area of the compound crust are due to small chan nels that drain these areas. These channels are not distinct features on the aerial photographs. Larger channels on the compound crust can be detected as darker areas within the large compound crust. These channels meander through the crust, dissolving soluble salts, eroding the crust, and depositing sands. This leaves interchannel areas of undisturbed platforms with one to two feet of relief.

From observations and x-ray diffraction analysis, the crust morphology of the salt pavement is due to the mineral content of the crust. A platy surface of

calcite and halite exists at the SCE . It is hard and dense and forms a rind on the surface approximately one to three inches thick. This rind buckles up and breaks apart upon dessication. Underlying this rind is approximately two to three inches of unconsolidated salt. Gaylussite was found in the southeast corner of the disturbed plot and center of the undisturbed plot at the SCE w'hen the 60

surface rind was removed and exposed the damp underlying salt layer. Underly ing the unconsolidated crust is a thick crust. This subsurface crust is composed of calcite and aragonite. Crust thickness increases from 12 inches at the east to 18 inches at the center and 24 inches at the west end of the SCE. The subsurface crust is extremely hard and requires a pick to break through. Soluble salts make up five to seven percent by weight of the underlying salt pavement at the site. During the persistent rains in May, 1987, the surficial calcite-halite rind was com pletely dissolved, leaving only the underlying calcite crust.

Crust morphology and mineralogy changes gradual^ from a platy to puffy texture approximately 0.5 miles west of the SCE. Change in texture can be seen on the aerial photographs, where the darker, smoother areas of the crust are platy pavements and the lighter, rough textured surface is the salt pan. Lake Minerals has developed their operations on the margins of the salt pan.

This puffy textured surface consist of a hard rind approximately 1/4 to one inch thick of calcite and halite. Underlying this protective cover is a light, unconsolidated layer of trona. At one location, one mile northwest of the SCE. a hard, dense crust similar to the underlying crust at the site was found under the light salt. This dense crust consisted of gaylussite and calcite.

During the dessication of Owens Lake in the 1920s’, only sodium sulfates

and carbonates were reportedly precipitated from the brines (Black, 1956). The presence of calcite and gaylussite (Ca,Na carbonate), which was also identified by Smith and Pratt (1957), indicates the crust covering the lake bed around the salt pan is a secondary replacement of the original salt crust. Chemistry of the inter stitial brines at the SCE indicates groundwater is not the source of calcium. The salt pavement may have precipitated from flood waters since the lake dried. Pre cipitation on the lake and runoff from the mountains washed the original soluble 61

crust to the salt pan. Calcium from the volcanics in the Coso Mountains and southern Inyo Mountains precipitated from the flood waters as they flowed across the lake bed, evaporated, and became saturated with calcite. Reactions between calcite and the concentrated brines may have formed gaylussite.

M udflats

The mudflat environment of Owens Lake occurs adjacent to beach deposits and areas of spring discharge. The largest areas of exposed lake bottom muds occur along springs and drainages leading to the salt pan (Plates 7). Mudflats are smooth textured, dark green close to the spring discharge areas and large channels, and dark brown further away from the drainages and springs. This is likely due to formation of salt crusts over the mud, masking their green color.

It appears lake bottom sediments are exposed 0.1 to 0.2 miles south of High way 190 near Dirty Socks and one mile east of the dune field on the west flank of the Coso Mountains. These patches are approximately 0.5 to one mile long and 0.2 to 0.5 miles wide. They are easily distinguished from fan deposits by the dark brown tone, lack of vegetation, and high drainage density with trellis mor phology. The muds east of the dune field are at an elevation of 3,760 feet. The patch near Dirty Socks is in a topographic low at 3,620 feet elevation.

Mudflat distribution in the Olancha-Cartago area demonstrates the influence of runoff on surface morphology. Mudflats are dark green adjacent to the spring mounds two miles east of Cartago and at the evaporation ponds at Cartago. Drainage density is very high along the spring mounds and around the ponds (Plate 7). The principal drainage at the south end of Owens Lake bed is formed by runoff around the most southern evaporation pond. Dark green muds are exposed in the northern ponds and along the drainages eroding through them. 62

Ihe southern two ponds have a light to dark brown salt crust in them indicating the south and west berms are still intact and prevent flooding of the ponds. The same process has occurred in the evaporation ponds near the Sulfate Plant well. Berms that have been eroded allow water to wash out salts from the ponds.

Ponds that have not been flooded contained a hard salt crust similar to the underlying crust at the SCE.

A fairly well-defined contact between the mudflat and salt crust at the Per- manente springs may be due to a change in the degree of surface wetness. The salt crust forms a narrow strip between beach ridge deposits and mudflats further out on the lake bed. It appears the salt crust has formed on the coarser sediment on the north side of the beach ridge. The water table is relatively deep because of the coarse sediments. Unsaturated conditions at the surface allow salt to pre cipitate without being redissolved. Further out on the lake, clays are saturated at the surface because of capillarity. Spring discharge and runoff dissolves the salts from the mudflat.

The mudflat is dark brown and drainage density is low east of the spring mounds, indicating spring discharge is significantly less than the west side. This dark brown surface occurs north along the drainage adjacent to the spring mounds. The dark brown mudflat and salt crust to the east form a linear, northwest trending, well defined contact. This contact coincides with the drainages from the east side of the spring mound line. Similar contacts between salt crusts and mudflats along the southeast lake also are bordered by drainages on the mudflat. 63

Beach Ridges

Beach deposits occur at approximately 3,600 feet elevation and are almost continuous around the perimeter of Owens Lake bed. Those shown on Plate 5 are beach ridges that extend below 3,600 feet. In some areas, ridges are covered by prograding alluvial fans with some patches of beach deposits exposed. Beach deposits are characterized by linear ridges parallel to the lake margins and a high vegetation density along the ridges.

The most extensive beach deposits occur at the north lake bed margin. Weathered shorelines occur at a maximum elevation of 3,665 feet and consist of alternating dark and light brown bands that strike almost east-west. Ridges strike into and abruptly end at the south Dolomite Loop alluvial fan. Vegetation is concentrated on the light brown, coarse textured ridges.

Beach ridges along the western half of Owens Lake are sharper and better defined than those along the eastern half of the lake bed. This is likely due to the sediment sources for the alluvial fans that have been reworked by waves. Sediments from the Sierra Nevada are coarse and would require high wave energy to disperse the sediments. The Inyo and Coso Mountains consist of finer sedi ments and would form less resistant beach ridges.

Channel morphology changes at the contact between alluvial fans and allu vial sediments reworked by waves along the Sierra Nevada Mountains. At this contact, channels become much wider and deeper. Braided channels merge into one single large channel. Maximum elevation of this contact is about 3,680 feet west of Ash Creek and PPG. Beach ridges formed in these areas trend parallel to the fan lobe. 64

Dunes and Megaripples

Sand dunes outside the 3,600 feet elevation contour are located two miles east of Olancha and one to two miles north of Keeler. The dunes east of Olancha are approximately one half mile wide and almost two miles long, with the long axis oriented approximately N20E. Bedforms are poorly developed on both the Keeler and Olancha dunes. Dune fields north of Keeler are about 0.2 by 0.5 miles in area with the long axis oriented about N40W.

Two large dune fields have formed on the lake sediments east of Cartago (two square miles) and west of Keeler (2.6 square miles). Bedforms are moderately to well defined on both fields. Dunes at the south field strike approx imately N45W and those near Keeler approximately N35E. Westec (1984) describes megaripples as bedforms up to six inches high and dunes in the south ern field up to 20 feet.

S alt P a n

Owens Lake salt pan is the largest playa environment in the basin. Most of the salt pan was covered by water in 1986 when the aerial photographs were taken. The margins of the salt pan are at an elevation of approximately 3,555 feet and have been mined by Lake Minerals along the south to northeast margins.

The exposed salt pan is distinguished from other playa environments by its’ coarse textured surface and lighter color. These characteristics are due to the soluble and hydrous minerals which accumulate in the sink. 65

Spring Mounds

The largest cluster of spring mounds occurs along a line at the south end of the lake bed (Plate 5). Smaller spring mounds (not shown) occur south of the Sulfate Plant road and north of Keeler. Chemistry of the spring mound discharge at the south end of the lake is very similar to that of springs and wells at Cartago, indicating the extent of Sierra Nevada recharge.

Spring mounds occur where the potentiometric surface is higher than land elevation. Water seeps out along weaknesses and margins of confining layers and discharges at the surface. The dilute water washes salts from the surface and allows vegetation to take root. Wind blown sand and silt accumulates and forms a mound around the vegetation and spring.

HYDRO GEO CHEMISTRY

Water chemistry is the primary control on salt crust mineralogy in Owens Lake basin. The initial chemical character of water flowing into the basin is con trolled by mineral dissolution of the surrounding mountains. Evolution of water chemistry along flow paths follows distinct trends that are determined by the ini tial solute concentrations. Minerals become saturated by evaporative concentra tion and precipitate from solution. The residual waters become relatively enriched in the excess solutes and depleted in the deficient solutes comprising the salt. Silicate dissolution is the primary control on chemical evolution paths in Owens Lake basin. Large volumes of water draining from the Sierra Nevada slowly dissolve the batholith and evolve into the N a -H G O z waters that dominate the basin chemistry. Springs and wells were sampled on and around the lake basin. Chemical analysis from these samples are given in Appendix 1. Locations of these samples are shown in Plate 4. 66

Water chemistry in Owens Lake basin can be separated into five groups with each indicating source areas and stages in brine evolutions. These groups are: l)

HGOz-Na+K-Ca of the western lake margin; 2) HCOz-Na +K-Mg of the northeast lake margin; 3) HGOz-Cl-Na+K-Mg of the southeast lake margin; 4) HGOs-Cl-

Na+K of playa brines; and 5) mixing of the first three groups with the brines. Stiff diagrams of spring and well chemistry are shown on Plate 4. Figure 14 shows the ionic ratios of the spring and well water chemistry. Clustering of sam ples in the Na and HCOs fields demonstrates the dominance of these ions in water chemistry throughout the basin.

West Lake Bed Margin

Water quality along the Sierra Nevada is excellent and ranges from 100 to 600 ppm total dissolved solids (TDS). Water quality decreases to the north and east. This trend reflects the distance from recharge areas. Spring and well TDS at Cartago (samples 14-16 in Appendix 1) and Cottonwood Springs (sample 24) is 100 to 200 ppm. Both areas are in close proximity to recharge on the alluvial fans, so infiltrating water has little time to react with sediments. TDS at sample

13 and north of PPG (samples 27, 29-31) is 300 to 600 ppm. These samples are further from their recharge areas of Cartago, western Alabama Hills, and upper Owens Valley. Groundwater at these springs and wells has had more time to dis solve aquifer sediments.

Chemistry of the Sierra Nevada waters is dominated by HC03-Na+K-Ca. This reflects the incongruent dissolution of silicates of the batholith. Weathering of plagioclase and potassium feldspar releases Ca, Na, K , and HCOz into solution and produces a clay precipitate. \o

FIGURE 14. Trilinear Diagrams Showing Ionic Ratios of Owens Lake Water Chemistry. 68

The increase in Na+K without corresponding increase in Ca for the more concen trated waters could be due to precipitation of calcite in the alluvial fans. Low

concentrations of K may be due to low proportions of potassium feldspar in the calc-alkaline batholith and the high adsorptivity of potassium onto clays.

Equilibrium between solutes and minerals wras determined with WATEQ. This program uses a chemical analysis to calculate solute activities and satura tion indices of the minerals that may precipitate from solution. Calcite is the first mineral to reach saturation along flow paths and controls further trends in

chemical evolution. Dilute waters at Cartago, Cottonwood Springs, and PPG are undersaturated with respect to calcite, indicating waters at the earliest stages of evolution. Other samples along the western basin are saturated with calcite.

VvATEQ results indicate further dissolution of calcium bearing sediments results

in calcite precipitation in the aquifers. The disproportionate Ca and HCOs con

centrations leads to increasing Na+K and HCOz concentrations in the direction of probable flow paths. These trends are seen between samples unsaturated and saturated -with calcite.

Cottonwood Springs chemistry demonstrates the major changes in chemistry that can occur within a short distance. This is a meadow with dense grass and other vegetation. Springs discharge and flow approximately 100 to 200 yards across the vegetated area and through a flume at the east side of the meadow. Sample 24, from the spring orifice, has virtually the same chemistry and TDS (168 ppm) as the Cartago area. Sample 25, from the flume approximately 100 yards from the spring orifice, has 4.5 times the total dissolved solids and different ionic ratios. Evaporation increases the concentration of Na+K, Cl, K, and S04 within the spring discharge area. Adsorption may remove some K and S04.

Increased HCOs is likely due to combined effects of evaporative concentration and plant respiration increasing C02 of the water and disequilibrium with the atmo sphere. The disproportionate increase in HCO& to Ca may be due to calcite pre cipitation. At saturation, the calcite activity product must remain constant.

Since Ca concentrations are less than HCOs in the waters, the proportion of HGO& must increase to maintain equilibrium with calcite. This is evidenced by change in undersaturation to saturation with calcite from sample 24 to 25.

Mixing of Sierra Nevada waters and lake brines is prevalent from Lake Minerals (sample 17) to Ash Creek (sample 23). Sierra Nevada w’ater chemistry is not completely masked by the concentrated brines. Braley Creek contains the highest proportion of metavolcanics in its drainage area and discharges west of Lake Minerals. Dissolution of metavolcanics in the Braley Creek drainage is evi dent by the high Ga and Mg concentrations at Lake Minerals and south of Per- manente (sample 18). These w'aters are just saturated to oversaturated with cal cite. High concentrations of Ca and Mg do not occur in mixing areas at and north of Permanente (samples 19-21), so it is unlikely brines are the source of alkali earths. Other waters’ identity along the Sierra Nevada is masked by the brines due to non-unique ionic assemblages in the initial waters.

Increased concentrations north of Lake Minerals to Permanente reflects the decreased influence of Braley Creek recharge to prevent brine migration into springs. Higher proportions of brine seep into marginal faults due to decreased fresh water heads further from the recharge source. The sudden decrease in con centration at Permanente and decreasing concentration northwrard reflects the influence of Ash Creek recharge to dilute brine mixing in the marginal faults.

Except for the lack of Ca and Mg, ionic proportions are very similar to water south of Permanente. Ionic proportions remain essentially constant because dilute recharge produces insignificant changes in chemistry. Northeast Lake Bed Margin

Well water chemistry of the northeast quadrant of Owens Lake is similar to the Braley Creek area and reflects the dolomite source rock of the Inyo Moun tains. TDS ranges from approximately 600 to 1,100 ppm with chemistry dom

inated by Na+K, Mg, and HCOz. Unlike the Braley Creek area, Mg concentra

tions are significantly higher than Ca. This is due to incongruent dissolution of dolomite and possibly metavolcanics. As dolomite dissolves, waters reach satura

tion with calcite and become relatively enriched with Mg. All waters in this area are oversaturated with calcite. The major differences between waters in this area is the amount of alkali earths in well water. Samples 1 and 5, taken higher on the alluvial fans, have higher concentrations of Mg and Ca. Low alkali earth con centrations at Swansea could be due to magnesium calcite precipitation along groundwater flow paths or within the well casing. This was a grab sample from standing water in the well and may not accurately represent the groundwater quality.

Sample 8, water chemistry of the spring south of the Sulfate Plant road, is the same as that of water at Keeler, but at an advanced stage in evaporative con centration. The sample was taken from an area of dense vegetation near the spring orifice. Evaporation and plant respiration may rapidly change water chemistry, similar to Cottonwood Springs. Alkali earths are precipitated in the spring discharge area, leaving Na +K as the only cations in solution. Alkali earth precipitation (indicated by calcite saturation) and C02 degassing decreases HC03 concentrations relative to other anions. Evaporative concentration enriches the water in N a+K , S 0 4, and Cl to approximately double the concentrations at the Keeler well. 71

Mixing of lake brines and Inyo Mountain recharge is evident from spring and well chemistry along the lake bed margin. TDS and chemistry are similar to the mixing zone near Permanente. This indicates that recharge along the Inyo Mountains maintains enough fresh water head to prevent significant amounts of brines from mixing in the marginal faults and aquifers. Changes in water chem istry along groundwater flow paths are best exemplified by the Keeler well (sam ple 5) and samples 3 and 4, located at increasing distances from the Keeler well. Sample 3 is slightly oversaturated with calcite and magnesite and still has the

high Mg concentration of its source water. Sample 4 was taken from a spring

about 200 yards from 3 on the lake bed. This sample has much less Mg and a higher saturation indices, indicating precipitation of magnesium calcite or mag nesite along flow paths. This trend is towards chemistries virtually identical to the samples 6 and 7.

Loss of S 04 along flow paths is probably due to reducing conditions of lake sediments, but could also be due to adsorption. Oxygen is depleted because organic rich clays, which reduce oxygen by the reaction:

CH20 + 0 2=G 02+H20 are in much greater abundance than the oxygen supply. Other oxidizing agents

(■NO&, Mn02, Fe20 3) are likely in low concentrations and are consumed by the organics. Sulfate is the next abundant oxidizing agent available. Reduction of

S04 to H2S is catalyzed by bacteria within the aquifers. End products of this process are H2S, C02, and methane. Both H2S and methane were found at the old well at Keeler (Lee, 1906). Hydrogen sulfide -was detected by its strong odor at samples 4 and 7. Lack of SOA in the mixing waters along the Inyo Mountains is the main difference between mixing waters near Permanente. 72

Southeast Lake Bed Margin

Water chemistry and TDS along the Coso Mountains (Plate 4) indicates mixing of Coso Mountain recharge and brines occurs in this area. The Coso Mountains have approximately the same lithology as the Sierra Nevada, which has recharge waters with TDS of 100 to 600 ppm. It is reasonable to assume that Coso Mountain recharge has similar (<1,000 ppm) TDS. Total dissolved solids of springs along the Coso Mountains are approximately 5,000 to 7,000 ppm, approximately twice the concentration of mixing waters along the Inyo and Sierra Nevada Mountains. No dilute waters of similar quality to the Inyo Moun tains were found. This suggests the amount of recharge along the Coso Moun tains is insufficient to reduce salt water intrusion along the lake bed margin.

Chemistry of source waters is not completely masked by brines. High con

centrations of Mg and Ca reflects the volcanics in the Coso Mountains. High con

centration of N a+ K , Cl, and HCOz at samples 9 and 10 indicates brine chemistry is the dominant influence on spring and well water chemistry. These samples are in approximate equilibrium with calcite. Samples taken further out on the lake

(11, 12) are oversaturated with calcite and deficient in Ca, indicating calcite pre cipitation along these springs.

B rines

Brines were sampled from 6 and 18 feet deep piezometers at the SCE. These

waters are dominated by Na-Cl-HCOs-SOi with Cl and HCOs the dominant anions.

Calcium and Mg are virtually absent. TDS of the shallow and deep piezometers were 124,600 and 141,900 ppm, respectively, when sampled in July, 1986. TDS was 159,800 and 201,900 ppm when sampled in July, 1987. 73

Increased concentration of all solutes in 1987 is likely due to re-solution of surface salts by the persistent rains in April and May, 1987. Both shallow and

deep piezometers show a 10 to 27 percent decrease in the proportion of HOOz to

Cl with the larger decrease in the deeper piezometer. This indicates solution of

predominantly Cl salts at the surface. Sulfate increased approximately 9 percent m the shallow piezometer and remained constant in the deep piezometer relative

to chloride. The IC/Na ratio increased 33 percent in the deep piezometer and

remained constant in the shallow piezometer. Changes in the SOi/Cl and K/Na ratios may be due to solution of sylvite (KC1) and differential movement of ions under density gradients. Saturation of brines with respect to calcite prohibits

re-solution of the calcite crust, keeping Ca and Mg concentrations at 1 to 3 ppm.

Composition of brines is typical for evaporated waters derived from granitic terrains. Saturation of calcite in waters with originally high proportions of

HCOz/Mg+Ca leads to the Na-Cl-HCOz brines by evaporative concentration. Sul fate concentrations are likely derived from sulfide oxidation in the Darwin Mining District and Cerro Gordo Mine because of the large amounts of sulfides occurring in these areas.

SA L T N O R M

Further classification of waters in Owens Lake basin wTas done with the pro gram SALT NORM (Bodine and Jones, 1986). This program determines the equilibrium ideal assemblage of salts that wrould precipitate if the water were taken to dryness in one step at 25’ C and one bar. This simulated evaporation does not consider brine evolution along flow paths or brine-solid interactions. Also, some of the minerals used to precipitate certain solutes are not naturally occurring. This is done to remove solutes which would normally react with solids and not undergo evaporative concentration. Therefore, normative salt assem blages calculated with SALT NORM should be considered ideal and may not represent salts which actually precipitate. These assemblages give an indication

of salts which could form by evaporative concentration. Simple salts calculated by SALT NORM are recast from the normative salts. This is a list of anhydrous simple salts comprising the normative salts and only considers major solutes. Simple salts are used for classification and comparison of waters and do not represent an equilibrium salt assemblage. Sodium chloride is represented as AfloC'/o to maintain a consistency of a -2 charge for anions. Based on SALT

NORM results, there are three groups of water in Owens Lake basin: l) CaCO3-

Na2C03 waters of the west lake margin; 2) MgCOg-NaCl waters of the northeast

lake bed margin; and 3) NaCl-Na2G03 waters of the mixed zones, Coso Mountains, and brines. Results of SALT NORM calculations are given in Table 3.

CaC03-Na2C03

Sample 16 was chosen to represent initial Sierra Nevada waters which have not mixed with lake brines or undergone significant evaporation. The high mole percent of Ca+Mg carbonates supports the earlier conclusion that this is water at an early point in chemical evolution. It is unlikely Ca and Mg will precipitate as dolomite because of the slow kinetics of dolomite formation. Magnesium calcite probabh precipitates in the aquifers and surface where springs become saturated with calcite. Pirssonite is a mineral that typically forms by reaction of minerals with saturated brines and would not be expected to form directly by evaporation. Thenardite and halite are minerals which could possibly precipitate, but only after considerable evaporative concentration because of their high solubilities.

Potassium minerals are rare because of their high solubilities and loss of K by adsorption onto clays (Drever, 1982). Table 3. SALT NORU Results

Sample 16

Normative salt assemblage Simple salts percent %(wt) mole w eight P ir s s o n it e Na2Ca (C03)2.2H20 53.79204 67.09879 D olom ite CaMg (C03) 2 14.12948 13.42399 Na2C12 3.70835 4.09414 K2S04 T h e n a rd ite Na2S04 7.79605 5.70510 2.94492 4.84704 Aphthitalite K3Na (S04) 2 3.22789 5.52797 Na2S04 5.72338 7.67848 C a lc it e CaC03 8.22139 4.23955 Na2C03 32.71758 32.75382 MgC03 H a lit e NaCl 12.19403 3.67168 8.59388 6.84401 CaC03 N it e r KN 0 3 0.63912 0.33292 46.31190 43.78251

Total 100.00000 100.00001 T o ta l 100 . ooooo' 100.00001

Sample 5

Normative salt assem blage Simple salts percent

% (mol) %(vt) mole w eight D olom ite CaMg (C03) 2 14.58003 21.45782 Na2C12 18.17314 20.04066 H a lit e NaCl 40.90056 19.07738 K2S04 4.06407 6.68137 M agnesite MgC03 27.01835 18.18101 Na2S04 11.17030 14.96883 B u rk e ite Na6C03(S04)2 5.52277 17.19293 Na2C03 16.66956 16.66883 Trona NaHC03 .Na2C03. 2H20 8.82369 15.91721 MgC03 36.96640 29.40552 Aphthitalite K3Na (S04) 2 3.04887 8.08832 CaC03 12.95654 12.23481 N it e r KN03 0.10574 0.08532 T o ta l 100.00000 100.00000 T o t a l 100.00000 99.99999

Sample 7

Normative salt assem blage Sim ple salts percent

% (mol) %(vt) mole w eight

Trona NaHC03 .Na2C03. 2H20 57.21059 83.21436 Na2C12 17.98775 19.35435 H a lit e NaCl 38.75959 14.57718 K2C12 1.66781 2.28915 S y lv it e KC1 3.59377 1.72412 K2S04 0.07007 0.11240 D olom ite CaMg (C03) 2 0.25990 0.30842 Na2S04 0.02336 0.03054 Aphthitalite K3Na (S04) 2 0.05033 0.10766 Na2C03 79.65176 77.71343 M agnesite MgC03 0.12583 0.06827 MgC03 0.35802 0.27787 CaC03 0.24123 0.22226 T o t a l 100.00000 100.00001 T o ta l 100.00001 1 0 0 .ooooo 76

Table 3. SALT NORM Results (Continued)

Piezometer (6 feet)

Simple salts percent

% (mol) %(vt) mole weight Trona NaHC03.Na2C03. 2H20 23.80635 48.74639 Na2C12 44.07091 44.74031 NaCl 72.26443 38.26015 K2S04 2.85467 4.32041 B u rkeite Na6C03(S04)2 2.33655 8.25661 Na2S04 6.65140 8.20543 Aphtliitalite K3Na (S04) 2 1.56030 4.69850 Na2C03 46.41277 42.72514 N ite r KN03 0.02510 0.02299 MaC03 0.00137 0.00100 P lr s s o n it e Na2Ca(C03)2 .2E20 0.00615 0.0134S CaC03 0.00887 0.00771 Dolom ite CaMg (C03) 2 0.00112 0.00188 T o ta l 100.00001 100.00001 T o ta l 100.00000 100.00000

Sample 10

Normative salt assemblage Simple salts percent

%(mol) %(wr) mole weight

Trona NaHC03 . Na2C03. 2H20 22.45531 50.25320 Na2C12 45.24993 47.55391 H a lit e NaCl 69.93082 40.46558 K2C12 1.70085 2.28012 Dolom ite CaMg (C03) 2 1.72573 3.15086 K2S04 1.16091 1.81882 Maanesite MgC03 2.66156 2.22189 Na2S04 0.38697 0.49418 tohthitalite K3Na (S04) 2 0.59804 1.96823 Na2C03 43.59027 41.53909 S y lv it e KC1 2.62855 1.94025 MoC03 5.67774 4.30411 CaC03 2.23333 2.00978 T o ta l 100.00000 100.00001 T o ta l 100.00000 100.00001

Sample 20

Normative salt assemblage Simple salts percent

%(^) mole weight

Trona NaHC03 .Na2C03. 2H20 41.99681 70.08287 Na2C12 28.29535 29.75092 H a lit e NaCl 54.61665 23.56639 K2S04 3.06470 4.80392 ADhthitalite K3Na (S04) 2 1.97186 4.83921 Na2S04 1.02936 1.31521 Dolom ite CaMg (C03) 2 0.84225 1.14670 Na2C03 65.27599 62.23544 M acnesite MgC03 0.56866 0.35399 McC03 1.46191 1.10878 B u rkeite Na6CC3 (S04) 2 0.00376 0.01083 CaC03 0.87270 0.78573

T o ta l 100.00000 100.00000 T o ta l 100.00000 100.00000 77

Salts expected to precipitate along the Sierra Nevada would be magnesium cal cite in the lower alluvial fans adjacent to the lake bed. Groundwater does not reach saturation with alkaline earth carbonates until it has reached this point as indicated by WATEQ. Magnesium will not likely precipitate as dolomite due to the slow kinetics of dolomite precipitation. Magnesium should be taken out of solution during precipitation of calcite to form magnesium calcite. Bicarbonate

epm is greater than the sum of Ca and Mg epm concentrations. Calcite precipita tion should lead to increased bicarbonate concentrations along evaporation paths

because HCOs is in greater concentration than calcium. Chemical evolution of waters along the Sierra Nevada should follow trends of increasing N a - H C 0 3- S 0 <-

Cl concentrations and lead to trona-thenardite(mirabilite)-halite salt assemblages on the lake bed.

MgCOs-NaCl

Sample 5 was chosen to represent initial waters along the Inyo Mountains.

The high mole percent of MgC03 and relatively low percent CaC03 is likely due to mcongruent dissolution of dolomite in the Inyo Mountains. High sulfate concen trations relative to the western lake margin is likely due to oxidation of sulfides from the Cerro Gordo Mine.

As with the west lake margin, dolomite will probably not form because of its

slow kinetics. Total epm of Ca and Mg is less than HCOs, so all alkali earths will

precipitate as carbonates. High concentrations of Mg may actually lead to mag nesite precipitation as indicated by SALT NORM. Trona, burkeite, and halite precipitated from the initial dessication of Owens Lake in the 1920s (Black, 19o6). This suggests SALT NORM may accurately predict salts which form at high concentration from the northeast lake bed margin. 78

NaCl -Na2COz

N a C l and N a ^ ° s are the dominant simple salts in waters from samples 7, 10, 20, and brines. The dominance of these constituents in marginal springs and wells is due to the large influence on water chemistry from mixing small amounts of brines with dilute inflow. Assuming lake brines with 100,000 ppm TDS. it

would take approximately 5 percent by volume of lake brines to obtain marginal springs with 5,000 ppm TDS.

Trona and halite constitute greater than 90 mole percent of normative salts computed by SALT NORM. Total sulfate salts of the normative salts comprise less than 4 percent for all samples.

Chemical Trends

Evaporative concentration, precipitation, and other processes control trends m water chemistry at Owens Lake. These processes can be inferred by plotting various ions versus a conservative ion to see trends along evaporation paths. Chloride salts are the most soluble in Owens Lake basin and do not precipitate until final stages of brine evolution. This makes Cl the best tracer to use in determining on solute concentrations. One to one slopes of the following figures are placed through the mean value of the data.

Figure 15 is a plot of Cl vs. dl80 . Both of these constituents are considered ideal tracers and should follow a linear trend with increasing concentrations by evaporation. At low concentrations of Cl, dlsO remains invariant with increasing

Cl concentration. This indicates possible dissolution of chloride salts by recharg ing waters and mixing of lake brines with dilute recharge. Highly concentrated brines have d1&0 values of approximately -2 per mil. LEGEND • data point — 1:1 slope

1 I------0 1 Log(CI) (epm)

FIGURE 15. dlfl0 vs. Chloride 80

If these brines mix with dilute water with d180 equal to -16 per mil, the

resultant mixture would contain di80 of approximately -15 per mil and log(C7) of

approximately 1.7. This assumes brines with Cl of 1000 epm and dilute waters

with 2 epm Cl, approximately the value of sample 5 and a 1:20 mixing ratio of brines to dilute water. Thus, mixing and chloride salt dissolution could account

for the small variability of d'*0 with Cl for discharge from springs and wells.

Once waters emerge at the surface and evaporate, the concentration of d180

and Cl increase. The slope is greater than 1:1 because of disequilibrium evapora

tion, where the rate of d180 concentration is greater than evaporative concentra tion of ionic components.

Figures 16 and 17 are plots of chloride vs. sodium and total carbonate, respectively. Both graphs show similar trends, indicating a connection between sodium and total carbonate concentrations. Initial waters in chemical evolution have a high proportion of Na and HCOs+COs to chloride. This is likely due to silicate dissolution releasing Na and HCOs into solution and controlling water chemistry because igneous rocks are the dominant rock type in the basin. Since the rock types in the basin do not contain significant amounts of Cl, the primary source of Cl in these waters is precipitation.

Intermediate waters of both graphs show a roughly 1:1 correspondence between plotted constituents. This indicates evaporative concentration of solutes without precipitation of sodium or carbonate salts. Total carbonate shows greater deviation from a 1:1 slope at higher concentrations of Cl for intermediate wmters. Log(HC03 + C03) (epm) Log(Na) (epm) -1 0- 1- 2 3-i - 3 - 4 5-i - / — 11 slope 1:1 - — • d ata point point ata d • / • data point point data • LEGEND *1:1 LEGEND IUE 7 Ttl carbonate Total 17. FIGURE / -1 / slope / IUE . oim s Chloride. vs. Sodium 1 6. FIGURE' S / • / • / . • / . A o(I (p ) (epm Log(CI) o(I (p ) (epm Log(CI) / / * • • / • • • • # vs / / Chloride / / 8 1 82

The decreasing proportion of total carbonate to Cl is likely due to loss of total carbon with increasing pH by the reaction:

2HC0S=C03+H20+C 02

W ith increasing pH, carbonate equilibria is shifted toward increased concentra tions of carbonate ion. Carbon dioxide is formed to maintain a mass balance while the alkalinity remains constant.

At high concentrations, total carbonate shows greater deviation from a 1:1 slope. Only one sample, the shallow piezometer, shows a significant decrease in sodium. This could be due to brines reacting with the calcite crust at the SCE to form gaylussite. This is difficult to verify based on one sample. Further loss of total carbon by degassing C02 could account for the continued decrease in total carbonate.

Chloride vs. potassium concentrations (Figure 18) show similar trends to chloride vs. sodium. Initial waters have relatively high concentrations of potas sium, indicating potassium feldspar dissolution. Intermediate and concentrated v aters shov a roughly 1.1 increase with Cl due to evaporative concentration. This trend is not expected because potassium readily undergoes ion-exchange with clays and should be removed from solution as chloride concentrations increase. Continual increase in potassium concentrations could be due to the high propor tion of illite in lake clays (Langer and Kerr, 1966). Illite has a low cation exchange capacity and may not adsorb enough potassium to significantly decrease concentrations relative to chloride. 3 -i LEGEND 2 - • data point — 1:1 slope / 1 - / £ Cl CD 0 -

CD O -1

/ -2

- 3 i 0 1 2 3 4 Log(Cl) (epm)

FIGURE 18. Potassium vs. Chloride. ^ co

**& 3 - 84

Chloride vs. sulfate concentrations, shown in Figure 19, shows a trend of decreasing sulfate relative to chloride in the intermediate waters. These samples are from the northeast portion of the lake bed and margin. Sulfide oxidation

yields high SO, concentrations in initial waters. As waters flow through the

organic rich sediments, SO, is reduced to H2S by oxidation of the organics. Elec

tron balance is maintained by formation of HCOs by the reaction:

S0,+2CH20=H2S+2HC03

Adsorption has also been suggested by Jones et al. (1977) as a mechanism of sul fate loss in the dilute stages of brine evolution.

Isotop es

Isotopic composition of waters from selected wells and springs around Owens Lake bed reflects their recharge source waters and processes to discharge. Isotopic composition is measured relative to standard mean ocean water (SMOW). Dur ing evaporative concentration, heavy isotopes will fractionate into the residual solution because of their lower vapor pressure. A negative value for deuterium and oxygen-18 indicates their concentrations are less than that of ocean water. The more negative the number, the less evaporation has occurred. Isotopic com positions of selected springs and wells are given in Appendix 2.

Figure 20, a the plot of deuterium vs. oxygen-18, shows the springs and wells sampled for isotopes. Deviation from the meteoric wrater line is due to eva porative concentration of spring and lake brines. 85

2 - LEGEND

data point 1 - - 1:1 slope

E 0- Q_

^ -I' o Nc/>--’ o - 2 ■

-3-

-4-

I T------r -1 1 2 Log(CI) (epm)

FIGURE 19. Sulfate vs. Chloride.

FIGURE 20. Owens Lake Isotope Samples vs. Craigs’ (1961) Meteoric Water Line. 86

Two distinct clusters occur along the meteoric water line. The lighter clus

ter, centered at approximately -15.5 o/oo d™0 and -122 o/oo dD, is from all wells sampled except for Cartago Flowing well and are from samples located in the northern half of the basin. Only one spring, sample 3 near Keeler, is included in this cluster and is the lightest of all samples. The second cluster, centered at

approximately -14.2 o/oo d'*0 and -110 o/oo dD, contains the rest of the springs and sample 16 (a well at Cartago) and are from samples located in the southern half of the basin. The isotopic composition of sample 10 plots intermediate

between the two clusters. This could be due to different precipitation patterns of

the Coso Mountains. The dD value of -122 occurs in the center of the lighter group and is significantly lighter than the second cluster. Therefore, sample 10 is most like the first cluster.

The correlation between isotope composition and type of sample reflects the amount of evaporative concentration that has occurred and possibly two sources of groundwater. Well samples and sample 4 may be representative of the moun tain block recharge or groundwater from the upper Owens Valley. However, it is unlikely aquifers from the upper valley extend to the basin margins near Keeler and PPG. This would be required for these wells to be tapping waters with the same isotopic composition as the upper Owens Valley. Wells tap the formation waters at greater depth and out of the influence of evaporation.

Spring isotope composition may be due to evaporative concentration before the water recharges into the fans. It could also be due to evaporative concentra tion along the flow path between recharge and discharge areas through the vadose zone, or evaporation at the spring outlet. Depth of evaporation effects extends at least 18 feet, as indicated by the piezometer samples. Therefore, it is likely evaporation at the spring outlet is the more important factor. 87

Piezometers were sampled at six and 18 feet for isotopes. The heavy water of these samples is typical of brines in closed basins which have undergone con siderable evaporation. High evaporation rates at the surface have produced the heavier water at six feet. Heavy, but lighter isotopic composition at 18 feet indi cates possible mixing of surface brines with deeper water of lighter composition. Rainfall on the lake may force the dense brines down to mix with deeper brines. The trend of heavier waters at the surface is consistent with the vertical upward flow indicated by the piezometer wrnter levels.

Salt Inflow

Surface inflow and groundwater evaporation transport salts to the surface of Owens Lake. Total salt inflow from surface and groundwater was estimated from the chemical analysis of springs, wells, and brines and estimated volumes of inflow from each source. Surface inflow from the marginal springs, wells, and Owens River transports approximately 17,000 tons per year of salt to the surface of Owens Lake. This estimate is based on 10,800 acre-feet per year of spring and well discharge with a weighted mean TDS of 800 ppm and 10,700 acre-feet of

Owens River discharge with a TDS of 300 ppm. Groundwater evaporation from the exposed lake bed transports approximately 270,000 tons of salt per year to the surface. This value assumes approximately 2,000 acre-feet per year of bare soil evaporation and all groundwater has a total dissolved solids of 100.000 ppm.

WATER BUDGET

The Owens Lake basin water budget is a quantification of the total average annual volume of water entering and exiting the basin and the volumes of water that occur along -certain flow paths within the basin. The budget allows 88

estimating the relative importance of the components of inflow to the basin and their possible influence in salt production. Three boundaries were established to quantify the amount of water flowing into certain parts of Owens Lake basin: 1) the hydrographic divide; 2) the groundwater basin boundary; and 3) the Owens Lake bed boundary.

Hydrologic Boundaries

The hydrographic divide of Owens Lake basin is defined as the topographic divide that separates surface runoff that flows directly into Owens Lake from sur face water that flows into the Owens River and adjacent basins. The western divide is the Inyc^Tulare County line along the crest of the Sierra Nevada Moun

tains. The northeast to southeast boundaries occur along the crest of the Inyo

and Coso Mountains and includes Centennial Flat. The southern and northern boundaries have been placed to separate surface flow into Haiwee Reservoir and

Owens River from surface inflow to Owens Lake. The hydrographic divide encloses an area of approximately 630 square miles. It is assumed that the gioundwater divides coincide with the hydrographic divides.

The groundwater basin boundary is defined as the basement rock-valley fill contact, excluding Centennial Flat. This boundary separates rocks capable of storing and conducting large volumes of wTater from the relatively impermeable mountain blocks. This boundary encloses a surface area of approximately 270 square miles. Total volume of water into the basin is measured across this boun dary- . \ ( W tv'A V % 0> WSAi Via Hw , 89

The Owens Lake bed boundary is defined as the 3,600 feet elevation contour, approximately the contact between alluvial fan and lake sediments. This boun dary is established to quantify total flow into Owens Lake and encloses a surface area of approximately 114 square miles.

Base Period

A base period was established for the water budget to compare volumes from various sources of gaged flow. This base period was selected to be water year 1940 to water year 1980 because lake elevations have the shortest period of record. This 41 year base period is considered satisfactory to estimate mean flows into Owens Lake basin. Mean values for the base period are used to account for the total volume into the lake for the entire period.

Figure 21 is a schematic flow diagram of the components of the water budget starting with the four sources of inflow to the basin and ending with lake evaporation. These components are discussed in their order of sequence on the flow chart.

Inflow' Components

Precipitation

Precipitation is the largest component of inflow to the groundwater basin. Total precipitation within the groundwater boundary was estimated by planimetering areas between isohyets of the LADWP map and the map constructed by this author. This isohyetal map, shown in Figure 22, was constructed by multi ple regression of precipitation as a function of elevation and distance from the Sierra Nevada crest. Data used in the regression are given in Table 1. PRECIPITATION rcMTCMM... . TUPPEn OWENS VALLEY MOUNTAIN BLOCK CENTENNIAL FLAT SUBSURFACE FLOW RECHARGE MOUNTAIN RUNOFF OWENS RIVER

xerophyte aqueduct lake bed Ian subsurface ovopotrans diversion precipi channel aqueduct -plralion tation runoff recharge runoff flow recharge diversion runoff

Owens Lake Groundwaler over r i } aqueduct lake marginal bare soil shreatophylf springs evapotrans- springs and wells evaporation plralion

total inflow across direct Inflow lake boundary fo Owens Lake T f------Inflow to Owens Lake evaporation

total Owens Lake Inflow

evaporation

FIGURE 21. Schematic Flow Diagram of Owens Lake Water Budget, oCO 91

4 miles

6. 000- precipitation (inches) Owens Lake bed boundary

hydrographic divide highway

groundwater basin boundary

FIGURE 22. Owens Lake Isohyetal Map. 92

Figure 23 shows the relation between precipitation and elevation without considering the rainshadow effect created by the Sierra Nevada Mountains. It is assumed that precipitation within the lowest value isohyet is equal to the value of that isohyet. Precipitation is assumed to change linearly between isohyets as indicated by Figure 23. The mean value of two isohyets was multiplied by the area to obtain the total volume of precipitation between the isohyets.

A maximum value of 78,200 acre-feet was obtained from the author’s isohyetal map, which estimates greater precipitation on the lake bed and Sierra Nevada alluvial fans than the LADWP map. A minimum value of 72,600 acre-feet was obtained from the LADWP map; a difference of 6 percent between the two maps. The groundwater basin area was planimetered from both maps to make sure pre cipitation values could be compared. From the LADWP’s map, an area of 273 square miles was obtained and 262 square miles from the authors’ map. This is a difference of four percent and is considered acceptable to make comparisons. A mean value of 75,400 acre-feet is used in the water budget.

R u n o f f

Runoff from the surrounding mountains is the second largest component of inflow to the groundwater basin. The majority of mountain runoff is from the perennial streams draining the eastern Sierra Nevada Mountains. LADWP has gaged five major creeks along the Sierra Nevada at the aqueduct and at the gioundwater basin boundary for Cottonwood Creek. All drainages are class D based on Lee’s (1912) classification of drainages for the Independence area. mean precipitation at station (inches) IUE 3 Peiiain s Eeain o Es ad et ie o Oes Valley. Owens of Sides West and East for Elevation vs. Precipitation 23. FIGURE 10 - 0 2 15 2 0 - 5 5 00 00 00 00 12000 10000 8000 6000 4000 v at aly ersin line regression valley east et aly ersin line regression valley west at aly data valley east et aly data valley west lvto o peiiain tto (feet) station precipitation of elevation LEGEND

at aly rcptto = 32 + 0015*(elevafion) 1 0 .0 0 + 2 .3 2 - = precipitation valley east west valley precipitation = — 1.56 + 0.001 9*(elevation) 0.001 + 1.56 — = precipitation valley west

r2= 2 0.95 r2= o.99 94

Cottonwood Creek is the most significant creek flowing into Owens Lake basin. It drains an area of 44 square miles, 55 percent of which is above 10.000 feet elevation. This is the most crest exposure of any drainage in the Owens Lake area. Differences between the gages at the upper fan and aqueduct are mostly due to infiltration into the alluvium. Vegetation along the creek is sparse and can be assumed negligible in comparison to the large volume of streamfiow. Mean annual flow at the upper gaging station for the base period is 15,113 acre- feet (Figure 24). Mean annual flow at the aqueduct is 8,569 acre-feet (Figure 25).

Percent stream loss varies inversely with total streamfiow. Mean percent stream loss was calculated by determining percent loss for each year and mean value of the annual percent loss, equal to 55 percent. Figure 26 shows gaged losses vs. total streamfiow for the period of record. Years with high discharge (>

35,000 acre-feet) show a trend of decreasing total recharge. Figure 27 is a graph of percent stream loss vs. total stream discharge shows a gradual decrease in per cent stream loss with increasing discharge. This is likely a function of the infiltration capacity of the streambed sediments and the distribution of flow over the year. Largest monthly streamfiow occurs from May to July. During these

months, streamfiow exceeds infiltration and a large percentage reaches the aqueduct, h ears with high annual flow show a rapid decrease in streamfiow after

these months. This narrows the range in infiltration that can occur and limits

the maximum recharge to approximately 10,000 acre-feet at 23,000 acre-feet total discharge. Minimum recharge occurs when total flow is less than the infiltration capacitj'' of the streambed sediments. This amount of recharge occurs over a stream length of approximately 1.6 miles. IUE 5 Ctowo Cek icag a te Aqueduct, the at Discharge Creek Cottonwood 25. FIGURE

Frequency ^ Frequency E 4 Ctowo Cek at Creek Cottonwood 24. RE 994 t 1979-80. to 1939-40 ipit f icag Itra (acre—feet/year) Interval Discharge of Midpoint pe Gage, Upper 994 t 1979-80. to 1939-40

9 5 IUE 7 Pret tem Loss Stream Percent 27. FIGURE IUE 26. FIGURE Volume of Recharge (acre-feei/year) 10000 12000 2000 - 0 0 0 4 - 0 0 0 8 - 0 0 0 6 100 - -, - - -, 0 / Discharge. 1935 — 1935 36 Discharge. Creek Cottonwood vs. Loss Stream Volume icag. 953 t 1983-84. to 1935-36 Discharge. / :/ ‘ v /. ' *• / / • ' • • •• . . total stream discharge above fan (acre —feet/year) (acre fan above discharge stream total 10000 10000 oa sra icag aoe a (acre—feet/year) fan above discharge stream total 1 0000 0000 ✓ * ✓ ' I I 0 0 0 0 2 0 0 0 0 2 I l o 1983-84. to s Ctowo Creek Cottonwood vs. squared = 0. 000 0 ,0 1 5 < X < 0 0 1 , 3 ; 5 .8 0 = d e r a u q s R 7 , oss = 394 — ) e g r a h c s i d ( n l * 6 3 — 4 9 3 = s s lo 0 0 0 0 3 0 0 0 0 3 I I 0 0 0 0 4 0 0 0 0 4 cluae recharge calculated - — • data point point data • \

| ------ersin curve regression - - daa point ata d •

LEGEND LEGEND 0 0 0 0 5 0 0 0 0 5 | 1 9 6 97

The runoff coefficient is defined as the total volume of water drained from a basin divided by the basin area. Using the mean gaged runoff of 15,113 acre-feet, the runoff coefficient for Cottonwood Creek drainage is 0.54 feet. This is approx imately one half the value Lee (1912) obtained for class D drainages in the Independence area.

Ash Creek, with a drainage area of 15 square miles, is the second largest gaged creek draining the Sierra Nevada. LAD A VP gages this, and all other creeks, only at the aqueduct. Lee’s (1915) ten year mean measured flow at the Ash creek fan apex is approximately 4,200 acre-feet. Precipitation records for Lee’s ten year period are not given, but mean flow at the upper gage of Cottonwood Creek for this period is 25,752 acre-feet. This is approximately 60 percent greater than the mean flow for the base period of this study. Decreasing Lee’s mean Ash Creek flow by 60 percent gives a mean annual flow of 2,500 acre-feet. Mean annual flow at the aqueduct for the base period is 2,775 acre-feet (Figure 28). This indi cates that comparisons between Cottonwood Creek drainage and other drainages in Owens Lake basin cannot be done on a linear basis.

Decreasing Lee’s ten year mean of 4,200 acre-feet by 10 to 20 percent gives a possible range of 3,400 to 3,800 acre-feet for the base period. This represents stream losses of 18 to 27 percent over a distance of 0.6 miles. This is reasonable considering the distance and percent loss at Cottonwood Creek.

The amount of crest exposure and topography of Ash Creek is very similar to the rest of the Sierra Nevada drainages in the Owens Lake area. Total runoff from all other drainages into the groundwater basin could best be estimated by computing the runoff coefficient for AlsIi Creek. Using the above range of values, the mean annual runoff coefficient for Ash Creek is 0.38 feet with a range of 0.35 to 0.4 feet. Frequency IUE 8 Ah re Dshre t h Audc, 994 t 1979-80. to 1939-40 Aqueduct, the at Discharge Creek Ash 28. FIGURE ipit f ihre nevl (acre-feet/year) Interval Dicharge of Midpoint 99

Total flow from the other drainages can be estimated by using the range of runoff coefficients of Ash Creek. Applying this to Braley Creek, with a drainage area of 5.7 square miles, total flow is about 1,300 to 1,500 acre-feet with a mean

of 1,400 acre-feet. Mean annual flow at the aqueduct for the base period is 965 acre-feet (Figure 29). This represents a stream loss of 26 to 36 percent with a mean of 32 percent. This occurs over a distance of 0.6 miles, approximately the same as Ash Creek. Differences in percent recharge are probably due to the total volume of water discharging into the stream with the same length rather than hydraulic properties of the sediments. Braley Creek is much smaller than Ash Creek so stream flow is less across the fan. This increases the recharge potential as seen at Cottonwood Creek.

Total flow from Lubkin Creek, with a drainage area of 6.8 square miles, is approximately 1,500 to 1,700 acre-feet with a mean of 1,600 acre-feet. Carrol Creek, with a drainage area of 5.5 square miles, has a total flow of approximately 1,200 to 1,400 acre-feet with a mean of 1,300 acre-feet. Lubkin and Carrol Creeks have mean annual flow at the aqueduct of 377 and 213 acre-feet, respec tively (Figures 30, 31). This represents a mean loss of 76 to 84 percent for Lub kin and Carrol Creeks, respectively. Total flow from Lubkin Creek is split between two forks on the alluvial fan that merge approximately 3.5 to four miles from the fan apex. The merged creek flows another 1.5 miles before reaching the aqueduct. Carrol Creek flows about 3.8 miles across the alluvial fan before reach ing the aqueduct. F req uency IUE 9 Bae Cek icag a te qeut 994 t 1979-80. to 1939-40 Aqueduct, the at Discharge Creek Braley 29. FIGURE 5 7 5 19 14 18 22 26 20 34 3586 3245 2904 2563 2222 1881 1540 1199 858 17 ipit f icag Itra (acre Interval—feet/year) Discharge of Midpoint

m m m 100 101

Midpoint of Discharge Interval (acre—feet/year) FIGURE 30. Lubkin Creek Discharge at the Aqueduct, 1939-40 to 1979 — 80.

Midpoint of Discharge Interval (acre—feet/year) FIGURE 31. Carrol Creek Discharge at the Aqueduct, 1939-40 to 1979-80. 102

The rest of the Sierra Nevada drainages are not gaged. The remaining drainages with similar topography and crest exposure as Ash Creek are south of Braley Creek and have a total area of 33.8 square miles. Total annual flow from this area is 7,600 to 8,700 acre-feet with a mean of 8,200 acre-feet. Creeks from these southern drainages are not diverted into the Aqueduct.

Areas between drainages consist mostly of colluvium covered granitics. These areas are triangular shaped with the largest area at lower elevations. These characteristics do not allow for snow to accumulate and runoff is low as indicated by the lack of channels at their base. Based on elevations and mor phology, it is assumed that the range in runoff coefficients is 0.3 to 0.35 feet.

Total area of the colluvium along the Sierra Nevada is 18.5 square miles. Total runoff is approximately 3,600 to 4,100 acre-feet with a mean of 3,800 acre-feet.

Runoff from the Coso and Inyo Mountains is ungaged. The majority of the Inyo Mountains is similar in topography and elevation to Ash Creek. The main difference is the amount of precipitation, vegetation, and snow accumulation, which occurs mostly on the east side of the Inyo Mountains. Based on topogra phy, elevation, vegetation, and precipitation, it is assumed that the runoff coefficient from the Inyo Mountains for the base period is 0.25 to 0.35 feet with a mean of 0.3 feet. The area of the Inyo Mountains that drains directly into Owens Lake (excluding runoff into Centennial Flat) is 96 square miles. Total flow into the groundwater basin is approximately 15,400 to 21,500 acre-feet with a mean of 18,400 acre-feet.

The Coso Mountains have relatively gentle slopes, lower elevations, and a rougher surface texture than the Sierra Nevada and most of the Inyo Mountains. This is due to the deeply weathered granitic core and overlying volcanics. These features produce less runoff than would be expected for the Inyo Mountains. 103

Based on topography, elevation, and surface texture, it is assumed that the mean runoff from the Coso mountains for the base period is 0.25 feet per unit area with a range of 0.2 to 0.3 feet. Twenty four square miles of the Coso Moun tains drains directly into the groundwater basin. Total mean runoff is approxi mately 3,800 acre-feet with a minimum and maximum of 3,100 and 4,600 acre- feet, respectively.

The remaining drainage area of the Coso and Inyo Mountains drains into Centennial Flat. The Inyo Mountains are similar to the Coso Mountains in this part of the range. Total drainage area for each range into Centennial Flat is 35 square miles for the Coso Mountains and 24 square miles for the Inyo Mountains. Using runoff coefficients equal to the Coso Mountains for all drainage areas, total mean runoff into Centennial Flat is approximately 9,400 acre-feet with a range of 7,500 to 11,300 acre-feet.

The alluvial fan that has formed from runoff out of Centennial Flat into the groundwater basin is the largest fan along the east side of the basin and is com parable in size to fans along the Sierra Nevada. Assuming precipitation in Cen tennial Flat equals evapotranspiration, then all mountain runoff is either recharge or runoff out of Centennial Flat. Based on channel recharge along the Sierra Nevada Mountains, it is assumed 20 to 30 percent of runoff is recharge. Approxi mately 1,500 to 3,400 with a mean of 2,300 acre-feet occurs as subsurface flow from Centennial Flat into the groundwater basin. Approximately 6,000 to 7,900 acre-feet with a mean of 7,100 acre-feet occurs as runoff into the groundwater basin. Owens River

The Owens River is the third source of surface inflow to Owens Lake basin and is gaged at Keeler Bridge. This mean annual flow of approximately 10,700 acre-feet (Figure 32) is contributed to the basin for the base period assuming baseflow between the bridge and the groundwater basin boundary is negligible in comparison to the volume of flow at Keeler Bridge.

Subsurface Flow

Subsurface inflow to the groundwater basin is mostly from the upper Owens Valley. Mountain block recharge and Centennial Flat subsurface flow are less significant subsurface sources in comparison to the upper valley. The USGS is currently modeling the groundwater system of the upper Owens Valley. Prelim inary results indicate 10,900 to 18,100 acre-feet is flowing south of Lone Pine

(Danskin, Personal Communication). Until a more accurate range is determined, a mean of 14,500 acre-feet is used.

Approximately zero to 4,000 acre-feet of recharge occurs through fractures in the Sierra Nevada mountain block. This range was obtained by planimetering precipitation on the mountains and summing the amount of stream recharge. Approximately 102,000 acre-feet of precipitation, with a range of 89,000 to 115,000 acre-feet, falls on the Sierra Nevada. Stream recharge accounts for 16 percent of this precipitation. It is assumed a maximum of 20 percent of the total precipitation is recharge. This recharge occurs along approximately 30 miles of mountain front and equals approximately 65 acre-feet per mile of mountain front.

Based on measured and estimated inflow, total mean annual inflow for the base period to the Owens Lake basin is 169,200 acre-feet. Using ranges for the estimated values, maximum and minimum annual inflow are 184,700 and 153.900 acre-feet, respectively. Frequency 10 16 16 1 12 14 FIGURE 32. Owens River Discharge at Keeler Bridge, 1939-40 to 1979 — 1979 80. to 1939-40 Bridge, Keeler at Discharge River Owens 32. FIGURE 8 0 - 4 8 — 8

—

b< P b <° 'b ipit f icag Itra (acre-feet) Interval Discharge of Midpoint 5' & ’ 1 n 294 nf included nof 219745 and nul lw f 20017 of flow Annual ^ ^ ^ n histogram. in ein 4492 Median e n 10749 Mean

105 106

Groundwater Basin

Inflow to the groundwater basin can take several paths out of the basin. These paths are shown in the schematic flow diagram (Figure 21). Outflow from the basin along each path will be estimated with the best available data.

Lake Precipitation -1 The most significant inflow to the Owens Lake boundary is precipitation directly on the lake bed and lake itself. Total precipitation on the lake bed is 24,400 to 28,300 acre-feet, obtained from this authors’ and LAJDWP isohyetal maps, respectively. A mean of 26,300 acre-feet is used in the water budget. The mean annual lake elevation for the base period is 17,700 acres, approximately 25 percent of the area within the Owens Lake boundary. Based on the mean lake area, it is assumed 25 percent of the total precipitation falls directly on the lake. This equals an inflow to the lake of approximately 6,600 acre-feet with a range of

6,100 to 7,100 acre-feet. Runoff from the lake bed adjacent to the lake likely contributes some inflow. Due to lack of data, it is assumed a range of five to 15 percent of the remaining precipitation reaches the lake. Direct inflow to the lake from precipitation is approximately 7,300 to 10,300 acre-feet with a mean of 8,600 acre-feet.

Alluvial Fan Precipitation

Evapotranspiration from zerophytes on the northern portion of Owens Lake was measured by LADWP. Those plots in the Owens Lake area were located on the aerial photographs. Plots most similar in appearance to the alluvial fan vege tation from Cartago north are dominated by shadscale scrub with approximately 107

10 percent vegetation cover. Measurements at these plots are mostly 0.25 feet evapotranspiration per year with a range of 0.23 to 0.3 feet. Vegetation at the southern alluvial fans is denser and different in appearance.

Total fan area along the Sierra Nevada Mountains is 46 square miles. Total precipitation, obtained from planimetering the isohyetal maps, is 18,800 to 23,700 acre-feet with a mean of 21,200 acre-feet. Fan area from Cartago south is approximately 11 square miles. Based on vegetation on fans north of Owens Lake, it is assumed vegetation in this area has a maximum evapotranspiration rate of 0.4 feet. The weighted mean evapotranspiration rate for the entire fan area is approximately 0.3 feet. Based on the observed and weighted mean evapo

transpiration rates, it is assumed a range of 0.25 to 0.3 feet evapotranspiration occurs on the alluvial fans. Total evapotranspiration from zerophytes is 7,400 to 8,800 acre-feet with a mean of 8,100 acre-feet.

The remaining 11,400 to 14,900 acre-feet of precipitation that is not con sumed by evapotranspiration must either runoff or infiltrate into the alluvial fans. Interchannel morphology indicates a significant amount of precipitation infiltrates into the soils. This is reasonable for coarse sediments with large capil laries and low specific retention. Based on interchannel morphology, it is

assumed 20 to 25 percent of the remaining precipitation infiltrates into the allu vial fans. Recharge from precipitation is 2,300 to 3,700 acre-feet with a mean of

3,000 acre-feet. This represents approximately 14 percent of the total precipita tion on the Sierra Nevada alluvial fans.

Runoff from the fans can be computed as the difference between total precip itation, evapotranspiration and infiltration. Total runoff is approximately 9,100 to 11,100 acre-feet with a mean of 10,100 acre-feet. Since less precipitation and 108 only 30 percent (14 square miles) of the fan area is below the aqueduct, runoff from fans below the aqueduct can be assumed negligible. Virtually all runoff occurs above the aqueduct and is assumed to be exported out of the basin.

Both this author’s and LADWP’s isohyetal maps estimate approximately 16,000 acre-feet precipitation on the Inyo and Coso Mountain alluvial fans. This excludes the western flank of the Coso Mountains which drain into the agricul tural area south of Olancha. Total fan area is approximately 67 square miles. Inyo and Coso alluvial fans contain finer sediments than the Sierra Nevada and less precipitation. These factors are much less favorable to recharge from precipi tation. Based on the fine sediments and precipitation patterns, it is assumed evapotranspiration and surface runoff into Owens Lake are the only paths possible for precipitation.

Evapotranspiration studies indicate these alluvial fans have about 10 percent vegetation cover and are dominated by shadscale scrub. Evapotranspiration is 0.23 to 0.26 feet per year for plots with shadscale. Using this range, total evapo transpiration is about 9,900 to 11,100 acre-feet with a mean of 10,500 acre-feet.

Subtracting evapotranspiration from total precipitation, total runoff into Owens Lake is about 4,900 to 6,100 acre-feet with a mean of 5,500 acre-feet.

Precipitation on the area south of Olancha is about 10,000 to 13,400 acre- feet. This area is cultivated, with much more vegetation than the alluvial fans. It is assumed that virtually all precipitation is consumed by evapotranspiration and the amount of runoff is negligible. 109

Mountain Runoff

Runoff from the surrounding mountains travels along three possible paths in the basin: 1) infiltration into channels on the alluvial fans; 2) runoff into the

Owens Lake boundary; and 3) export out of the valley via the aqueduct. Phreatophyte vegetation along the stream channels is not dense, except for Lub- kin Creek. Evapotranspiration by phreatophytes in the stream beds is assumed negligible in comparison to total stream runoff, except for Lubkin Creek.

Recharge to the groundwater basin from mountain runoff occurs mainly along the Sierra Nevada Mountains. Most infiltration can be computed as the sum of the differences between estimated runoff and gaged flow at the aqueduct These differences sum up to a mean of 10,000 acr^feet with a range of 9,500 to 10,500 acre-feet for the gaged creeks.

Recharge from the ungaged areas must be estimated by comparing fans and stream lengths. Most runoff from the ungaged areas flow into Cartago and Olan- cha Creeks with stream lengths of 1.4 and 2.2 miles, respectively. This is com parable to Cottonwood Creek and two to three times the stream length of Ash and Braley Creeks. Channel morphology is much better developed than Cotton wood Creek indicating a finer sediment matrix. Based on channel morphology and length, it is assumed 35 to 45 percent of total streamfiow infiltrates into the channels. Recharge for ungaged areas south of Cartago Creek is about 2,700 to 3,900 acre-feet with a mean of 3,300 acre-feet. The remaining runoff flows is not diverted into the Aqueduct and flows into Owens Lake.

Runoff from colluvium is mostly between Cartago and Cottonwood Creek, with distances to the aqueduct about the same Ash and Braley Creeks. Based on distance to the aqueduct, it is assumed 25 to 35 percent infiltrates before reaching the aqueduct. Approximately 900 to 1,400 acre-feet with a mean of 1,100 acre- 110

feet recharges into the alluvial fans. Total mean sum of all recharge along the Sierra Nevada is 17,400 acre-feet with a range of 15,400 to 19,500 acre-feet, including recharge from precipitation.

Diversion of mountain runoff out of the basin via the aqueduct is the difference between total runoff, infiltration, and flow7 over the aqueduct. Flow at Cottonwood Creek over the aqueduct is the only significant overflow for gaged creeks during the base period, with a mean of 1,200 acre-feet. Total export, including runoff from precipitation, is about 23,600 to 25,600 acre-feet with a mean of 24,600 acre-feet.

Recharge from runoff along the Coso and Inyo Mountains occurs mostly along channels two to three miles long. Approximately 3,700 to 7,800 acre-feet with a mean of about 5,500 acre-feet enters the groundwater system assuming 20 to 30 percent of total runoff is recharge. These ranges are based on channel losses along the Sierra Nevada. Approximately 14,800 to 18,300 acre-feet with a mean of 16,700 acre-feet is surface flow across the lake boundary.

Subsurface Flow

Total subsurface inflow7 to Owens Lake groundw'ater basin is approximately 41,700 acre-feet wdth a range of 31,500 to 52,800 acre-feet. This includes inflow7 from the upper Owens Valley, Centennial Flat and recharge within Owens Lake

basin. Groundwater discharge occurs as marginal spring and well flow7, phreatophyte evapotranspiration, bare soil evaporation, and spring discharge directly into Owens Lake.

Springs and Wells

Most wells and spring discharge areas w7ere visited during the study and their flow7 rates measured with flumes or estimated by inspection. Sites that w7ere visited were located on the aerial photographs. Total spring and well discharge I l l

was estimated by comparing the number of measurements to the size of the area. Total spring and well discharge along and within the lake bed was estimated at 10,800 acre-feet. Given an error of 25 percent, maximum and minimum discharge is about 8,100 to 13,100 acre-feet, respectively. This is assumed to be representa tive of spring and well discharge for the base period due to lack of data on these springs and wells.

Phreatophyte Evapotranspiration

Phreatophytes along and within the lake margin were mapped using a JPL satellite image (LADWP, 1985) and infrared photograph (LADWP, 1977). Based on personal communication with Groeneveld (1987), all plants along the lake margin were assumed to be salt grass with an evapotranspiration rate of 40 inches per year. Phreatophytes at the Owens River delta and Cartago/Olancha area were assumed to be willow and cottonwood, each with an evapotranspiration rate of three feet per year. Cultivated areas south of Olancha were assumed to have an evapotranspiration rate of five feet per year. Total annual phreatophyte evapotranspiration is approximately 16,500 acre-feet. Given an error of 10 per cent due to planimetering error, evapotranspiration accounts for 14,900 to 18,100 acre-feet of loss from the groundwater. This includes phreatophyte evapotran spiration measured by Groeneveld (1986) in Lubkin Creek drainage.

Bare Soil Evaporation

Bare soil evaporation from the exposed lake bed, measured at the SCE, is approximately 0.45 inches per year. Total evaporation was computed as the sum of the mean monthly exposed lake area times the evaporation rate measured at the site. Mean monthly lake area is the total area within Ovsens Lake boundary less the mean monthly lake area less the area covered by dunes and megaripples. 112

Total bare soil evaporation is approximately 2,000 acre-feet. A range of 25 per cent is used for a minimum and maximum bare soil evaporation of 1,500 to 2,500 acre-feet, respectively.

Owens Lake Spring Inflow

Spring discharge directly into Owens Lake is calculated as the difference between total groundwater inflow and the estimated outflow from the other paths. This residual yields a range of 7,000 to 19,100 acre-feet with a mean of 12,400 acre-feet.

Owens Lake Boundary

From these estimates, there are approximately 84,000 to 112,000 acre-feet with a mean of 97,600 acre-feet flowing across the Owens Lake boundary. This

consists of surface water flowing across the exposed lake bed, direct precipitation, and subsurface flow. Total surface water flowing across the lake boundary is about 50,600 to 62,100 acre-feet with a mean of 56,900 acre-feet. Direct flow into Owens Lake is approximately 14,300 to 29,400 acre-feet with a mean of 21,000 acre-feet.

Actual flow into Owens Lake is measured by the lake elevations. Evapora tion of surface water across the lake bed is the only diversion possible before flowing in to Owens Lake. Assuming 25 to 35 percent of all surface water eva porates before entering Owens Lake, then approximately 32,900 to 46,600 acre- feet with a mean of 39,800 acre-feet of surface water actually flows into Owens

Lake. Total annual inflow to Owens Lake (surface plus direct inflow) is approxi mately 47,200 to 76,000 acre-feet with a mean of 60,800 acre-feet. 113

Lake Evaporation

Lake elevations were not consistently measured throughout the base period, particularly in the 1970s. The missing record was estimated by assuming a linear change between the recorded dates bounding the missing dates. There are only a few periods in which more than three months of data are missing. Lake eleva tions, volumes, and surface area for the period of study are shown in Figures BB SS. From Figure 34, it can be seen that lake storage remains roughly constant for the study period. This supports the assumption that storage changes equal zero.

Using the bathymetric graph for Owens Lake, the mean annual lake eleva tion, storage volume, and area were estimated for the base period (Figures 36-38). Mean annual lake elevation for each month during the base period was estimated

from the records by using the lake elevation measured in the middle of each month. Mean annual lake elevation is approximately 3,552.60 feet. Mean annual lake area for the entire year is 17,700 acres with mean annual volume in storage of 9,500 acre-feet.

Evaporation rates from Owens Lake have not been measured since its’ near dessication. Evaporation from the lake may vary considerably with dilution from inflowing water and evaporative concentration. A range in evaporation rates can be obtained by using a minimum rate of 45 inches per year obtained by Vor- ster(l985) at Mono Lake. This is also the value Lee (1915) estimates for the predicted limiting value of the lake specific gravity of 1.29. A maximum of 60 inches per year obtained by Lee (1915) when Owens Lake w7as still occupied by an extensive lake is used. For a mean open water area of 17,700 acre-feet, this gives a range in total annual evaporation from Owens Lake of 66,300 to 88,400 acre- feet with a mean of 77,400 acre-feet. IUE -. en nul wn Lk Vlm from Volume Lake Owens Annual Mean 3-4.FIGURE IUE 3 Oes ae lvtos rm 13 t 1980. to 1939 from Elevations Lake Owens 33. FIGURE lake volume (x1000 acre-feel) 994 t 1979-80. to 1939-40 1 14 115

FIGURE 35. Mean Annual Owens Lake Surface Area from 1939-40 to 1979-80.

FIGURE 36. Mean Monthly Owens Lake Elevation for 1939-40 to 1979-80. IUE 38. FIGURE Surface Area (acres) m Volume In Storage (acre—feet) UE 7 Wa Mnhy wn Lk Soae Volume Storaqe Lake Owens Monthly Wean 37. GURE 1 2000 H 2000 0 0 0 8 0 JAN

en oty wn Lake Owens Montly Mean 994 t 1979-80. to 1939-40 rm 13-0 o 1979-80. to 1939-40 from E MR P MY U JL U SP C NV DEC NOV OCT SEP AUG JUL JUN MAY APR MAR FEB \ \ ufc Ae from Area Surface

117

Estimated ranges of inflow to Owens Lake are approximately 16 to 29 per cent less than the estimated lake evaporation. Differences are likely due to errors in estimated ungaged flow from the Inyo and Coso Mountains and evaporation from the lake surface area. The bathymetric curves represent a best fit to sound ings made at the lake in the early 1900s. Small changes in lake elevation results in large changes in lake surface area. Significant error could result when estimat ing lake surface area at low elevations. A range in median lake elevation can be derived by using the same evaporation rates and estimated volumes of inflow to Owens Lake. Estimated lake surface area is approximately 11,700 to 14,500 acres with a mean of 13,100 acres. According to the bathymetric graph, this corresponds to a lake elevation of 3552.10 to 3552.3 feet.

Table 4 is a summary of the water budget for the entire groundwater basin. Values listed are sums of all sources in the basin comprising each component. For example, subsurface flow is a sum of upper Owens Valley groundwater flow into the basin, groundwater flow from Centennial Flat, and mountain block recharge. Evapotranspiration is a sum of zerophyte and phreatophyte evapotranspiration and the rainfall residual south of Olancha. 118

Table 4

Groundwater Basin Budget

Inflow (acre-feet)

component maximum minimum mean precipitation 78,200 72,600 75,400 runoff 70,300 58,200 64,300 subsurface flow 25,500 12,400 18,800 Owens River - - 10,700 total (rounded) 185,000 154,000 169,000

Outflow (acre-feet)

component maximum minimum mean evapotranspiration 51,400 42,400 47,000 aqueduct diversions 25,600 23,600 24,600 lake bed evaporation 38,700 34,800 36,800 lake evaporation 88,400 66,300 77,400 total (rounded) 203,000 167,000 186,000 119

SUMMARY AND CONCLUSIONS

The following items have been determined in this study:

1. Owens Lake basin consists of aquifers derived from sedimentation from the Owens River delta and the surrounding alluvial fans.

2. The north central part of the basin consists of well sorted, fine to medium grained sands that extend approximately five miles into Owens Lake and may constitute 50 percent of the stratigraphy for 3,000 to 4,000 feet. An aquifer 170+ feet thick is located in the center of the basin at approximately 750 feet from the surface and may be continuous to Haiwee Reservoir.

3. Marginal aquifers derived from the alluvial fans are most extensive at approxi mately 450 to 600 feet and extend up to two miles into Owens Lake. Cotton wood Creek alluvial fan and the fan south of Keeler are likely to have the best aquifer properties for development.

4. Difference in permeability between alluvial sediments and lake clays controls the location of springs. Tectonic faults appear to have insignificant influence on groundwater flow.

5. Distribution of salt crusts in Owens Lake is controlled by the amount of runoff from adjacent mountains and grain size of shallow sediments.

6. Salt crusts along the northwest to south lake bed are due to the Aqueduct diverting Sierra Nevada runoff and preventing salt crust dissolution.

7. Salt crusts occur along the southeast lake because of small volumes of runoff from the Coso Mountains. Water flows along drainages on the lake bed, dissolv ing and eroding crusts. Interchannel areas are undisturbed, with salt crusts up to two feet thick. 120

8. Lack of salt crust along the northeast lake bed is due to large volumes of runoff from the Inyo Mountains dissolving and eroding surface crusts. Shallow, coarse sediments may reduce capillarity from the groundwater and reduce the salt flux.

9. Salt crust morphology is dependent on crust mineralogy. Hard, platy crusts consist of cal cite and halite. Puffy crusts consist of trona with a hard rind of calcite and halite.

10. Chemistry of springs and wells reflects the source water and degree of mixing with lake brines. Dissolution of igneous rocks from the Sierra Nevada has pro

duced waters dominated by Na-Ca-HCOz along the western Owens Lake basin.

11. Springs along the Inj^o Mountains are dominated by Na-Mg-HCO3, reflecting the dolomitic basement rocks.

12. Springs along the Coso Mountains are dominated by Na-Mg-HCOz-Cl, result ing from the mixing of lake brines and wrnters derived from the volcanic terrain.

13. Lake brines are dominated by Na-HGOz-Cl.

14. Results of the program SALT NORM suggest calcite should precipitate along the lake margins near Cartago and Keeler. Further evaporation of inflowing water and lake brines should produce salt crusts of halite and trona. Sulfate

salts make up a small percentage of the normative salt assemblage calculated by SALT NORM.

15. Trends in water chemistry along flow paths is controlled by initial solute con

centrations and calcite precipitation. Bicarbonate is in greater concentrations

than Ca + Mg. Calcite precipitation leads to residual solutions concentrated in Na-HCOz. 121

16. Decreased N a concentrations in concentrated brines may be due to reactions between brines and surface crusts composed of calcite, forming gaylussite.

17. Evaporation of brines from the bare surface precipitates approximately 270,000 tons of salt at the surface of Owens Lake. Springs, wells, and Owens River transport approximately 17,000 tons of salt into Owens Lake basin.

18. Mean annual flow into Owens Lake basin for the base period 1939-40 to

1979-80 was approximately 169,200 acre-feet. Approximately 24,600 acre-feet is added to the aqueduct from runoff within Owens Lake basin.

19. Mean annual flow across Owens Lake boundary is about 97,600 acre-feet. This consists of approximately 56,900 acre-feet of surface water, 26,300 acre-feet of precipitation, and 14,400 acre-feet of subsurface flow'. Estimated flow reaching Owens Lake is approximately 60,800 acre-feet.

20. Differences between total inflow' and outflow are due to uncertainties in the

Inyo and Coso Mountain hydrology and errors in estimating lake surface area with small changes in lake elevation. REFERENCES

Bacon, Charles R., Giovanetti, Dennis M., Duffield, Wendell A., Dalrymple, G. Brent, and Drake, Robert E., 1982, “Age of the Coso Formation, Inyo County Califor nia,” USGS Bull. 1527, pp. 1-18. Banks, Harvey O., I960, Reconnaissance Investigation of Water Resources of Mono and Owens Basins Mono and Inyo Counties. A report by the Los Angeles Department of Water and Power, Los Angeles Black, Leroy G., 1956, Report on Owens Lake Sampling (1948-1955). A report prepared for the Los Angeles Department of Water and Power, Los Angeles Blackwelder, Eliot, 1931, “Pleistocene glaciation of the Sierra Nevada and Basin and Ranges,” Geol. Soc. America Bull., vol. 42, no.4, pp. 865-922. Bodine, M.W. and Jones, Blair F., 1986, “THE SALT NORM: A Quantitative Chemical-Mineralogical Characterization of Natural Waters,” Water Resources In vestigation Report 86-4086, USGS. Bouwer, H. and Rice, R.C., 1976, “A Slug Test for Determining Hydraulic Conductivity of Unconfined Aquifers with Completely or Partially Penetrating Wells,” Water Resources Research, vol. 12, pp. 423-28. Carver, Gary Alen, 1969, “Quaternary tectonism and surface faulting in the Owens Lake Basin,” M.S. Thesis 882, University of Nevada, Reno. Cochran, G.F., Lopes T.J., Mihevc T., and Tyler S., 1987, Study of Salt Crust Formation Mechanisms on Owens (Dry) Lake, .California (Draft), Water Resources Ce-nter, Desert Research Inst., Reno. Coleman, J.M. and Prior, D.B., 1982, “Deltaic Environments,” in Sandstone Deposition Environments, pp. 139-178, American Association of Petroleum Geologist Memoir 31. Cook, R.V. and Warren, A., 1973, Geomorphology of Deserts, B.T. Batsford Ltd., Lon don. Craig, H.,1961 , “Isotopic variations in meteoric waters,” Science, vol. 133, pp. 1702- 1703. Danskin, Wes, 1987, “Personal Communication,” USGS, San Diego . Department, of Energy, 1987, Site Characterization Plan: Yucca Mountain Site, Nevada Research and Development Area, Nevada, pp. 5-63-5-68, Office of Civilian Radioac tive Waste Management, Washington D.C.. Drever, James I., 1982, The Geochemistry of Natural Waters, Prentice-Hall, Englewood Cliffs. Droste, J.B., 1961, “Clay minerals in sediments of Owens, China, Searles, Panamint, Bristol, Cadiz, and Danby Lake Basins, California,” Bull. Geol Soc Am 72 dd 1713-1721. duBray, Edward A. and Dellinger, David A., 1981, “Geologic Map of the Golden Trout Wilderness, Southern Sierra Nevada, California,” USGS Aliscellaneous Field Studies Map MF-12S1-A. Duffield, Wend el A. and Bacon, Charles R., 1981, “Geologic Map of the Coso Volcanic Field and Adjacent Areas, Inyo County, California,” USGS Miscellaneous Investiga tion Series Map 1-1200. Eugster, H.P. and Hardie, L.A., 1978, “Saline Lakes,” Lakes: Chemistry, geology, and physics, pp. 237-293, Springer-Verlag, New York. Fetter, C.W., 1980, Applied Hydrogeology, Charles E. Merril Co., Columbus. Groeneveld, David P., Warren, Daniel C., Hubbard, Paula J., and Yamashita, Irene S., 1986, TRANSPIRATION PROCESSES OF SHALLOW GROUNDWATER SHRUBS AND GRASSES IN THE OWENS VALLEY, CALIFORNIA; PHASE I: STEADY STATE CONDITIONS. A report prepared for the Los Angeles Depart ment of Water and Power and Inyo County, Bishop Groeneveld, David P., 1987, “Personal Communication,” Inyo County Water Depart ment, Bishop. Hall, W'ayne E. and Mckevitt, E.M. Jr., 1962, “Geology and Ore Deposits of the Darwin Quadrangle Inyo County, California,” USGS Professional Paper 868, pp. 3-4. Hardie, L.A., Smoot, J.P., and Eugster, H.P., 1978, “Saline lakes and their deposits: a sedimentologic approach,” Modern and ancient lake sediments. Special Publication 2 International Association of Sedimentologist, pp. 7-41, Blackwell Scientific Publica tions. Hardie, L.A. and Eugster, H.P., 1970, “The Evolution of Closed-Basin Brines,” Minera- logical Society of America, vol. Special Publication 3, pp. 273-290. Houghton, John G., 1969, Characteristics of Rainfall in the Great Basin, p. 205, Desert Research Institute, University of Nevada Systems Reno, Nevada. Hutchison, William R., 1986a, “Updated Water Budgets, Owens Valley,” Inyo County Water Department, Bishop, vol. Report 86-2. Hutchison, V'illiam R., 1986b, Estimation of Baseflow: Owens River at Iveeler Bridge,” Inyo County Water Department, Bishop, vol. Report 86-4. JMLORD, 1984, Position Paper Water Supply Potential Cabin Bar Ranch (Cartage, Olancha, and Walker Creek). A report prepared for Cabin Bar Ranch by JMLORD., Fresno Jones, B.F., Eugster, H.P., and Rettig, S.L., 1977, “Hydrochemistry of the Lake Magadi basin, Kenya,” Geochem. Cosmochim. Acta, vol. 41, pp. 52-72. 124

LAD\VP, 1972, Water Resources Management Plan Owens Valley Ground Water Basin. A report by the Los Angeles Department of Water and Power, Los Angeles LADWP, 1976, Report on Owens Lake Water Balance Water Year 1968-69. A report by the Los Angeles Department of Water and Power, Los Angeles LADWP, 1977, False Color Infrared Photograph. Provided by the Los Angeles Depart ment of Water and Power, Los Angeles. LADWP, 1981, Report on Owens Lake Solar Salt Pond Preliminary Site Exploration. A report by the Los Angeles Department of Water and Power, Los Angeles LADWP, 1985, JPL Satellite Image of Owen Lake Basin. Provided by the Los Angeles Department of Water and Power, Los Angeles. LADWP, 1986, True color aerial photographs of Owens Lake Basin. Provided by the Los Angeles Department of Water and Power, Los Angeles. Langer, A.M. and Kerr, P.F., 1966, “Mojave Desert Playa Crusts; physical properties and mineral content,” Journal of Sedimentary Petrology, vol. 36, pp. 377-96. Lee, Charles H., 1912, “An Intensive Study of a Part of Owens Valley, California,” USGS Water Supply Paper 294- Lee, Charles H., 1915, Report on Hydrology of Owens Lake Basin and the Natural Soda Industry as effected by the Los Angeles Aqueduct Diversion. A report prepared for the Los Angeles Department of Water and Power, Los Angeles Lee, Willis T., 1906, “Geology and Resources of the Owens Valley, California,” USGS Water Supply Paper no. 181, p. 13. Le^ in, Harold L., 19i8, The Earth Through Time, p. 381, W.B. Saunders Company. Merriam, C.W., 1963, “Geology of the Cerro Gordo Mining District Inyo County, Cali fornia,” USGS Professional Paper f08. Motts, Ward Sundt, 1970, Geology and Hydrology of selected playas in the western United States, University of Massachusetts, Amherst. Nilsen, T.H., 1982, Alluvial Fan Deposits,” in Sandstone Depositional Environments, pp. 49-86, American Association of Petroleum Geologist Memoir 31. Pakiser, L.C., Kane, M.F., and Jackson, W.H., 1964, “Structural Geology and Volcanics of Owens Valley Region, California- A Geophysical Study,” USGS Professional Pa per 488, pp. 1-66. Perrine, Jeffrey R, 1983, Ground Temperature Survey and Additional Geohydrologic In vestigations, Cabin Bar Ranch Area, Geothermal Survey Inc., South Pasadena Prepared for Mr. Richard S. Stevens, c/o Wrather Properties Development, Long Beach, Perrine, Jeffrey R. and Birman, J.H., 1982, Preliminary Geohydrologic Investigations of Cabin Bar Ranch Area, Inyo County, California, Geothermal Survey Inc., South Pasadena . A report prepared for Cabin Bar Ranch by Geothermal Survey Inc. 125

Saint-Amand, Pierre, Mathews, Larry A., Gaines, Camille, and Reinking, Roger 1986 Dust Storms From Owens and Mono Valleys, California, Naval Weapons Center^ China Lake . Smith, G.I. and Pratt, W.P., 1957, “Core logs from Owens, China, Searles, and Panam- int basins, California,” USGS Bull. 10f5-A, pp. 1-62. Smith, G.I., Barczak, V.J., Moulton, G.F., and Liddicoat, J.C., 1983, “Core IvM-3, a Surface-to-Bedrock Record of Late Cenozoic Sedimentation in Searles Valley, Cali fornia,” USGS Professional Paper 1256. Smith, G.I., 1979, “Subsurface Stratigraphy and Geochemistry of Late Quaternary Eva- porites, Searles Lake, California,” USGS Professional Paper 10/8, p. 130. Smith, G.I., 1984, “Paleohydrologic Regimes in the Southwestern Great Basin, 0-3.2 m.y. Ago, Compared with Other Long Records of "Global" Climate,” Quaternary Research, vol. 22, pp. 1-17. Vorster, Peter, 1985, “A Water Balance Forecast Model for Mono Lake, California,” Monograph Forest Service/ USD A Region 5 10. Walker, Roger G., 1984, Facies Models, pp. 53-70,105-118, Geologic Association of Cana da. Westec, Services Inc., 1984, RESULTS OF TEST PLOT STUDIES AT OWENS DRY LAKE, INYO COUNTY, CALIFORNIA. A report prepared for the State Lands Commision, Long Beach by Westec Services, Inc., San Diego Appendix 1. Spring and Well Chemistry (Analysis given in ppm)

S a m p le S a m p le S a m p le pH h c o 3 c o 3 C l s o 4 n o 3 Na N u m b e r L o c atio n T y p e K Ca Mg Si TDS logca/(IAP/K)

T16S R37E 10d,b w ell 7.78 614.00 i . ND 9 1.50 0.60 0.04 100.00 2 0.10 45.60 65.60 83.00 1030.24 0.66 • 2 TICS R37E 24c,d w ell 9.00 304.00 4 2.40 8 4.00 1.70 0.2 6 166.00 20.00 6.20 13.20 11.00 637.66 0.60 3 TIBS R38E 31c,b sp rin g 7.49 1420.00 ND 30 0 .0 0 < 1 .0 0 < 0 .0 6 6 1 4 .0 0 6 7.70 17.60 7 4.20 7 7.00 2460.4 0.18 4 T ie s R 3 8 E 3 0d,d sp rin g 8.45 1810.0 4 2.80 467.00 3 .7 0 < 0 .0 6 3 9.70 3 .6 0 31.00 6.02 6 3.00 343.64 -0.64 6 TI7S R38E 4b,c w ell 7.06 698.00 ND 9 6.10 108.00 0.43 164.00 2 3 .4 0 37.80 66.40 61.00 1141.13 0.71 0 T17S R38E 9d,a w ell 8.44 1610.00 2 7.80 192.00 8 7.10 6 .3 0 70 6 .0 0 46.00 3.27 2.26 8 1.00 2664.62 0.38 7 T17S R38E 18c,d w ell 8.28 1740.00 6 6.60 26 4 .0 0 1.70 < 0 .0 5 8 3 6 .0 0 2 6.30 1.80 1.62 81.00 3008.00 0.04 8 T17S R38E 22a, c sp rin g 9.16 410.00 2 6 .6 0 2 1 0 .0 0 34 6 .0 0 < 0 .0 6 468.00 32.20 2.71 2.18 27.00 1636.89 0.36 0 T18S R38E 17b,b sp rin g 6.86 1660.00 ND 1180.00 638.00 < 0 .0 6 1340.00 3 3.80 69.90 106.00 122.00 4947.70 0 .0 0 10 T18S R37E 34a,a w ell 6.76 3070.00 ND 1630.00 7 2.80 < 0 .0 5 1080.00 108.00 43.20 66.60 124.00 7004.60 0.03 11 T18S R37E 34c,c sp rin g 9.68 1820.00 1290.00 2320.00 988.00 < 0 .0 5 3570 .0 0 188.00 3.10 0.20 127.00 10306.30 0.86 12 T19S R37E 4b,c sp rin g 0.39 1610.00 676.00 609.00 406.00 < 0 .0 5 1690.00 64.40 2.32 0.26 7 6.00 4930.97 0.70 13 T1«S R37E 6a,c sp rin g 8.66 137.00 6 .7 0 17.60 3 4 .2 0 < 0 .0 6 6 9.80 8.87 12.00 1.93 60.00 326.80 0.24 14 T18S R36E 36d,c w ell 7.45 92.60 ND 1.70 13.20 0 .0 0 17.20 1.76 18.00 2.14 3 0.00 177.40 0.71 16 T18S R36E 36d,c sp rin g 7.87 84.60 ND 2 .4 0 14.80 1.06 16.90 1.62 18.10 1.47 24.00 164.86 -0.33 18 T18S R36E 36d,b w ell 6.94 48.80 ND 1.20 3 .8 0 0.11 9.00 1.14 8.62 0.97 2 6.00 99.64 -1.77 17 T18S R37E 10b,c sp rin g 6.89 1070.00 ND 27 6 .0 0 20 4 .0 0 < 0 .0 6 6 2 6 .0 0 2 0.30 63.30 36.20 6 6.00 2249.8 -0.01 18 T18S R37E I8d,b sp rin g 7.80 1490.00 ND 494.00 26 2 .0 0 0.06 880.00 2 5.70 5 4.10 41.30 70.00 3307.16 0.81 19 T18S R37E 18a,a sp rin g 8.60 1230.00 40.80 29 2 .0 0 9 7.00 < 0 .0 5 895.00 16.20 • 7.40 6.09 3 3.00 2418.39 0.70 20 TI8S R37E 18a,a sp rin g 9.80 1000.00 66.40 27 6 .0 0 6 4.10 < 0 .0 6 62 8 .0 0 3 4.60 6.06 6.13 46.00 2116.28 0.42 21 T18S R37E 7d,c w ell 8.26 016.00 ND 24 8 .0 0 8 8.60 < 0 .0 6 6 2 6 .0 0 ' 23.80 12.60 7.62 46.00 1867.32 0.66 22 T18S R37E 6d,a sp rin g 10.20 1840.00 682.00 1080.00 84 8 .0 0 < 0 .0 6 2 0 8 0 .0 0 226.00 2.46 0.34 06.00 6764.79 0.87 23 T18S R37E 6d,b sp rin g 8.26 624.00 ND 81.60 26.40 < 0 .0 6 20 1 .0 0 64.50 14.60 6.32 36.00 953.22 0.61 24 T17S R37E 30c,b sp rin g 6.00 76.10 ND 11.20 18.80 2.61 12.10 2 .3 0 20.30 4.04 22.00 168.46 -1 .3 7 26 T17S R37E 30c,b sp rin g 8.64 201.00 8 .8 0 196.00 03.20 0.63 2 0 6 .0 0 12.00 36.00 7.20 21.00 780.73 0.60 Appendix 1. Spring and Well Chemistry (Continued)

S a m p le S a m p le S a m p le pH h c o 3 c o 3 Cl NO 3 Na N u m b e r L o c atio n T y p e s o i K Ca Mg Si TDS logc„,(IAF/K)

26 T17S R36E lc,a w ell 8.26 148.00 4.60 3 4.90 13.20 0.64 7 2.30 6.68 8.86 0.96 3 2.00 322.12 -0 .3 0 27 TICS R36E 23c,c sp rin g 7.36 146.00 ND 6 .2 0 6 9.10 0.12 3 9.70 3 .6 0 31.00 6.02 6 3.00 .343.64 -0.64 28 TIBS R36E 13c,b w ell 7.79 1410.00 ND 181.00 0 .2 0 0.26 199.00 27.40 46.30 189.00 98.00 2160.16 0.90 29 T ie s R 3 6 E 15c,* w ell 7.61 2.67 ND 2 2.10 3 8.30 6 .0 0 7 2.00 3.44 3 8.70 8.03 42.00 496.67 0.06 30 TICS R3CE 9a,d w ell 8.13 188.00 ND 2 6.10 48.00 0.12 68.20 4.71 2 4.10 4.80 3 9.00 402.03 0.32 31 T 1 6 S R3eE 10b,d w ell 8.24 303.00 ND 66.20 10.80 0.02 119.00 17.10 11.20 e.33 61.00 694.66 0.29 piezometer 6 ft. SCE T17S R38E 30*,c 9.67 40900.00 ND 321 0 0 .0 0 9380.00 19.6 40200.00 (1986) 2020.00 3 .2 0.3 62.00 124607.00 1.27

piezometer 18 ft. SCE T17S R38E 30a,c 9.66 46000.00 ND 368 0 0 .0 0 12100.00 9.3 (1986) 48700.00 2 3 20.00 3.4 1.1 6 9.00 141985.00 1.33

piezometer 6 ft. SCE. T17S R38E 30a,c > 1 0 47600.00 ND 42100.00 13000.00 < 0 .0 4 642 0 0 .0 0 2 9 40.00 (1987) 2.46 1.43 6 4.00 169899.00 1.26

piezometer 18 ft. SCE TI7S R38E 30a,c > 1 0 63100.00 ND 66700.00 20 3 0 0 .0 0 < 0 .0 4 67300.00 4520.00 (1987) 1.64 0.98 82.00 202004.00 1.16

ND — Not Done

lO 128

Appendix 2. Spring and Well Isotope Data

Sample # Sample Location Sample Type d180 dD

4 T16S R38E 36d,d spring -15.9 -125 5 T17S R38E 4b,c well -15.7 -119 7 T17S R38E 18c,d well -15.7 -123 9 T18S R38E 17b,b spring -14.2 -117 10 T18S R37E 34a,a well -14.7 -122 11 T18S R37E 34c,c spring -9.8 -90 13 T19S R37E 5a,c spring -14.0 -108 16 T18S R36E 36d,b well -14.2 -107 20 T18S R37E 18a,a spring -14.2 -109 25 T17S R37E 30c,b spring -14.3 -113 26 T17S R36E lc,a well -15.5 -119 30 T16S R36E 9a,d well -15.4 -118 31 T16S R36E 10b,d well -15.9 -121 SCE T17S R38E 30a,c piezometer 6 ft. -0.9 -54 SCE T17S R38E 30a,c piezometer 18 ft. -2.3 -60