Surface-Water and Ground-Water Quality in the 

Yucaipa Area, San Bernardino and Riverside 

Counties, California, 1996–98 

By GREGORY O. MENDEZ, WESLEY R. DANSKIN, and CARMEN A. BURTON 

U.S. GEOLOGICAL SURVEY 

Water-Resources Investigations Report 

Prepared in cooperation with the 

00-4269


SAN BERNARDINO VALLEY MUNICIPAL WATER DISTRICT
 5020-74


Sacramento, California


2001

U.S. DEPARTMENT OF THE INTERIOR 

GALE A. NORTON, Secretary 

U.S. GEOLOGICAL SURVEY 

Charles G. Groat, Director 

The use of firm, trade, and brand names in this report is for identification purposes only and 

does not constitute endorsement by the U.S. Geological Survey. 

For additional information write to: Copies of this report can be purchased from: 

District Chief U.S. Geological Survey 

U.S. Geological Survey Information Services 

Placer Hall, Suite 2012 Box 25286 

6000 J Street Federal Center 

Sacramento, CA 95819-6129 Denver, CO 80225 
CONTENTS 

Abstract.................................................................................................................................................................................. 1

Introduction ........................................................................................................................................................................... 1

Purpose and Scope....................................................................................................................................................... 2

Methods of Investigation ............................................................................................................................................. 3

Previous Investigations ................................................................................................................................................ 7

Acknowledgments ....................................................................................................................................................... 8

Description of Study Area ..................................................................................................................................................... 8

Physiography ............................................................................................................................................................... 8

Population and Climate ............................................................................................................................................... 8

Geology ....................................................................................................................................................................... 9

Hydrology.................................................................................................................................................................... 9

Land Use...................................................................................................................................................................... 11

Water Use..................................................................................................................................................................... 16

Water Quality......................................................................................................................................................................... 16

Surface Water............................................................................................................................................................... 16

Ground Water............................................................................................................................................................... 22

Flowmeter Data ................................................................................................................................................. 26

Depth-Dependent Samples ................................................................................................................................ 28

Isotopic Composition of Water .............................................................................................................................................. 29

Oxygen-18 and Deuterium .......................................................................................................................................... 29

Tritium ......................................................................................................................................................................... 31

Limitations and Future Needs................................................................................................................................................ 31

Summary and Conclusions .................................................................................................................................................... 34

Selected References............................................................................................................................................................... 34

FIGURES 

1–3. Maps showing: 

1. Location of the Yucaipa area in the Santa Ana River drainage basin, southern California............................... 2

2. Physiography of the Yucaipa area, southern California .................................................................................... 3

3. Selected wells and surface-water-quality sites in the Yucaipa area, southern California.................................. 4

4. Graph showing tritium activity in precipitation at Los Angeles, California, 1953–96 ............................................ 6

5–8. Maps showing:

5. Surficial geology of the Yucaipa area, southern California............................................................................... 10

6. Ground-water levels at selected wells in the Yucaipa area, southern California, spring 1997.......................... 12

7. Land use in the Yucaipa area, southern California, 1990.................................................................................. 14

8. Water chemistry in samples from selected wells and surface-water sites in the 

Yucaipa area, southern California ..................................................................................................................... 18

9. Trilinear diagrams showing major-ion composition of surface water and ground water in the Yucaipa area, 

southern California ................................................................................................................................................... 20

10. Map and graphs showing precipitation stations and cumulative precipitation for three February 1998 storms 

in the Santa Ana River drainage basin, southern California..................................................................................... 21

11. Boxplots showing concentration of selected constituents for selected wells and surface-water sites in the 

Yucaipa area, southern California ............................................................................................................................ 23

12. Map showing concentration of dissolved solids, nitrites plus nitrates, and dissolved oxygen for selected 

wells and surface-water sites in the Yucaipa area, southern California.................................................................... 24

13. Diagram showing driller’s log, electric logs, vertical flow rate, well construction, and water-quality sampling 

for well 1S/2W-25R4 in the Yucaipa area, southern California ............................................................................... 27

Contents III

14. Graph showing isotopic concentrations of delta deuterium compared to delta oxygen-18 by site and by storm 

for selected wells and surface-water sites in the Yucaipa area, southern California................................................ 30 

15. Map showing delta deuterium, delta oxygen-18, and tritium activity in selected wells and surface-water 

sites in the Yucaipa area, southern California .......................................................................................................... 32 

TABLES 

1. Location and characteristics of selected surface-water sites and wells in the Yucaipa area, southern California .. 13 

2. Chemical and isotopic analyses of water from selected surface-water sites in the Yucaipa area, southern 

California ................................................................................................................................................................ 36 

3. Chemical and isotopic analyses of water from selected wells in the Yucaipa area, southern California................ 39 

CONVERSION FACTORS, VERTICAL DATUM, ACRONYMS, AND ABBREVIATIONS, AND 

WELL-NUMBERING SYSTEM 

Conversion Factors 

Multiply By To obtain 

cubic foot per second (ft3/s) 0.02832 cubic meter per second 

foot (ft) .3048 meter 

foot per year (ft/yr) .3048 meter per year 

gallon per day per square foot [(gal/d)/ft2

] .3516 liter per day per square meter 

gallon per minute (gal/min) .003785 cubic meter per minute 

inch (in) 25.4 millimeter 

inch per year (in/yr) 2.54 centimeter per year 

mile (mi) 1.609 kilometer 

Temperature is given in degrees Celsius (AC), which can be converted to degrees Fahrenheit (AF) by the 

following equation: 

AF = 9/5(AC) + 32. 

Vertical Datum 

Sea level: In this report, “sea level” refers to the National Geodetic Vertical Datum of 1929 

(NGVD of 1929)—a geodetic datum derived from a general adjustment of the first-order level nets 

of both the United States and Canada, formerly called Sea Level Datum of 1929. 

Acronyms and Abbreviations 

mg/L milligrams per liter

Hg/L micrograms per liter

HS/cm microseimens per centimeter

δD delta deuterium

δ18O delta oxygen-18

per mil parts per thousand, as used with delta (δ) notation

pCi/L picocuries per liter

14C carbon-14

CCYN Carbon Canyon Dam

CONV Converse Fire Station

DEVO Devore Fire Station

GIS geographic information system

3

H tritium

IV Contents 
LKMA Lake Mathews

LSD Land-Surface datum relative to NGVD of 1929

MCL maximum contaminant level

MTS mountains

NO2 nitrite

NO3 nitrate

OAKG Oak Glen

PRDO Prado

SAR5 Santa Ana River 5th Street

SARM Santa Ana River near Mentone

SMCL secondary maximum contaminant level

SNTO San Antonio Dam

VSMOW Vienna Standard Mean Ocean Water

Well-Numbering System 

Wells are identified and numbered according to their location in the rectangular system for the 

subdivision of public lands. The identification consists of the township number, north or south; the 

range number, east or west; and the section number. Each section is further divided into sixteen 40-

acre tracts lettered consecutively (except I and O), beginning with “A” in the northeast corner of the 

section and progressing in a sinusoidal manner to “R” in the southeast corner. Within the 40-acre 

tract, wells are sequentially numbered in the order they are inventoried. The final letter refers to the 

base line and meridian. In California, there are three base lines and meridians; Humboldt (H), Mount 

Diablo (M), and San Bernardino (S). All wells in the study area are referenced to the San Bernardino 

base line and meridian (S). Well numbers consist of 15 characters and follow the format 

002S002W02M001S. In this report well numbers are abbreviated and written 2S/2W-2M1. Wells in 

the same township and range are referred to only by their section designation, 2M1. The following 

diagram shows how the number for well 2S/2W-2M1 is derived. 

Well 

2S/2W-2M1 

D C A 

E G H 

M L K J 

N Q R 

6 5 3 2 1 

7 8 10 11 12 

18 17 16 15 14 13 

19 20 21 22 23 24 

30 29 28 26 25 

31 32 33 34 35 36 

27 

R1W R1E 

T1S 

T1N 

T2N 

R2W 

RANGE 

TOWNSHIP 

R4W R3W 

T2S 

T3S 

R2W 

T2S 

MERIDAN 

BASE 2 

B 

F 

P 

4 

9 LINE 

Well-numbering diagram 

Contents V 
−

Surface-Water and Ground-Water Quality in the Yucaipa 

Area, San Bernardino and Riverside Counties, California, 

1996−98 

By Gregory O. Mendez, Wesley R. Danskin, and Carmen A. Burton 

ABSTRACT 

The quality of surface water and ground 

water in the Yucaipa area was evaluated to determine general chemical characteristics and to identify areas of recent ground-water recharge. Water 

samples, collected from 8 sites on 3 creeks and 

from 25 wells, were analyzed for general chemistry, nutrients, tritium, and stable isotopes of hydrogen and oxygen. At one production well 

(1S/2W-25R4), water samples were collected at 

discrete depths during pumping and a continuous 

profile of the vertical flow rate inside the well casing was recorded. In addition to general-chemistry 

samples, tritium and carbon-14 samples were collected at this well to interpret the age of water at 

different depths. 

Results indicate that most water in the 

Yucaipa area is a calcium-bicarbonate type. The 

general chemical composition of surface water 

resembles that of ground water, although the concentration of most constituents is higher in ground 

water. The chemical composition of most groundwater samples is similar. Elevated concentrations 

of nitrate in some ground-water samples may indicate recharge from agricultural areas. 

In surface water that recharges ground water 

tritium activity ranged from 7 to 18 picocuries per 

liter. The range of tritium activity found in ground 

water indicates different times since recharge and 

possible mixing along ground-water flow paths. 

The oldest ground-water sample had a tritium 

activity less than 0.3 picocuries per liter, indicating 

more than 50 years since recharge. Water samples 

that had tritium activity greater than 0.3 picocuries 

per liter indicate that some of the water was 

recharged since 1952. The youngest ground water 

(greater than 7 picocuries per liter) was found near 

the hills and mountains surrounding the Yucaipa 

area; the oldest ground water (less than 

0.3 picocuries per liter) was found in the Western 

Heights subbasin. 

Testing of the vertical contribution of 

ground water to well 1S/2W-25R4 showed that 

more than one-half of the water flowed into the 

well between depths of about 450 and 600 feet 

below land surface; the rest of the water flowed 

into the well between 600 and about 850 feet 

below land surface. At a discharge rate of 

750 gallons per minute, virtually no water was 

contributed to the well below a depth of about 850 

feet. The water samples collected at this well 

ranged in age from less than 50 to less than 400 

years before present. 

INTRODUCTION 

The Yucaipa area is about 12 mi southeast of the 

city of San Bernardino and about 75 mi east of the city 

of Los Angeles in the upper part of the Santa Ana River 

drainage basin (fig. 1). Since about 1970 and especially 

during the 1990’s, the widespread urbanization of 

southern California has extended inland from the coast 

into the Yucaipa area. Undeveloped land, agricultural 

land, and sparsely populated residential land have been 

converted into housing tracts. The net effect of this 

change in land use has been an increase in the demand 

for water, especially potable water for domestic use. 

Because the local supply of both surface water and 

ground water is limited in this semiarid region, water 

purveyors need an accurate assessment of water 

resources. This report assesses the quality of water in 

Introduction 1 
the Yucaipa area, primarily in the Yucaipa plain (fig. 2). analysis of these data was used to identify areas of 

The report will aid local water purveyors in under- recent ground-water recharge and evapotranspiration, 

standing and evaluating local resources and using them and to determine generalized ground-water flow paths. 

most effectively in combination with water imported The scope of this study was to collect and anafrom northern California and from the adjacent San lyze water samples from streams and wells in the Bernardino area. Yucaipa area. All samples were collected during 

1996–98 as composite (bulk) samples, which then were 

Purpose and Scope split into appropriate subsamples for analysis. Previously collected data, which did not include analysis for 

The purpose of this study, the results of which tritium or stable isotopes, were not included in this 

are presented in this report, was to survey the quality of study. Several water samples were collected from the 

surface water and ground water in the Yucaipa area. surrounding hills and mountains, but the focus of the 

Water samples collected as part of the study were ana- sampling and subsequent analysis was on water quality 

lyzed for general chemistry, nutrients, tritium, and sta- of the Yucaipa plain. A sample collected from Mill 

ble isotopes of hydrogen and oxygen. Preliminary Creek (fig. 3), which originates in the San Bernardino 

Figure 1. Location of the Yucaipa area in the Santa Ana River drainage basin, southern California. 

2 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
Mountains east of Yucaipa, represents ground water 

emanating as springflow from nearby bedrock. This 

water is imported into the Yucaipa Regional Park and 

used to fill recreational lakes, and then recharges the 

ground water. Six depth-dependent water samples were 

collected from a single production well (1S/2W-25R4) 

and were compared to vertical flow rates within the 

well. A geographic information system (GIS) was 

developed to locate wells, to aid in interpretation of 

water-quality data, and to prepare figures for this 

report. 

Methods of Investigation 

Collection of several areally distributed surfacewater samples was required to characterize surfacewater quality and to identify the likely interaction 

between surface water and ground water. Because 

streamflow on the Yucaipa plain is infrequent and of 

short duration, simply finding surface water to sample 

can be difficult in this semiarid region. Fortuitously, the 

winter of 1997–98 was an El Niño year with greater 

than average runoff. Three storms in February 1998 

Figure 2. Physiography of the Yucaipa area, southern California. 

Introduction 3 
Figure 3. Selected wells and surface-water-quality sites in the Yucaipa area, southern California. 

4 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
Figure 3—Continued. 

Introduction 5 
were selected to collect water samples. Streamflow was The strategy for sampling ground water was to 

sampled on Oak Glen and Yucaipa Creeks, which are collect samples throughout the Yucaipa area to identify 

the two primary streams in the area (fig. 3). Base-flow the general quality, the likely source of recharge, and 

samples were collected on upper Oak Glen Creek in the the dominant paths of ground-water flow. Nearly all 

foothills, where flow is present and originates as ground-water samples were obtained as bulk samples 

springflow from bedrock or as snowmelt. Yucaipa from discharge pipes of production wells. At a new proCreek originates in the southern part of the Yucaipa duction well (1S/2W-25R4), it was possible to obtain 

Hills and has no base flow. One water sample was col- depth-dependent samples under pumped conditions 

using a sampling technique described by Izbicki and lected from Mill Creek because part of its flow is others (1999). Coincident with sampling, the flow rate pumped into the Yucaipa area in a pipeline and then is inside the casing of the production well was measured 

discharged at the Yucaipa Regional Park. The imported using a spinner tool. Flow-rate measurements were 

water is used for recreational purposes before it infil- used to determine the relative contributions of ground 

trates into the ground. Water in the pipeline is a mixture water from different strata to the pumped well. 

of streamflow diverted in the upper Mill Creek drainage In this study, naturally occurring stable isotopes basin and streamflow diverted under Highway 38 (fig. of oxygen (oxygen-18) and hydrogen (deuterium) were 

3). Water from Mill Creek was collected as a single used to help determine the source of ground water and 

grab sample; other surface-water samples were col- to trace its movement. Atoms of oxygen-18 and deutelected, depending on the stream conditions, as either an rium have more neutrons and a greater atomic mass 

equal-width integrated sample or a grab sample. (weight) than do the more common isotopes, 

2,250 

Volume-weighted tritium 

Decay-corrected to 1996 

700 

2,000 

600 

1,750 

500 

1,500 

1,250 400 

1,000 300 

750 

200 

500 

100 

250 

0 0 

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 

YEAR 

Figure 4. Tritium activity in precipitation at Los Angeles, California, 1953–96. Tritium was corrected using techniques from Michel (1989). TRITIUM ACTIVITY, IN PICOCURIES PER LITER
 TRITIUM ACTIVITY, IN TRITIUM UNITS (TU)


6 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
oxygen-16 and hydrogen. This difference in weight 

results in differences in the physical and chemical 

behavior of the heavier, less abundant isotopes (International Atomic Energy Agency, 1981). 

Most of the world’s precipitation originates from 

the evaporation of seawater. As a result, the oxygen-18 

and deuterium composition of precipitation throughout 

the world is linearly correlated and often referred to on 

graphs as the meteoric water line (Craig, 1961). 

Oxygen-18 and deuterium abundances typically are 

expressed as ratios in delta notation (δ), as per mil 

(parts per thousand) differences, relative to the standard known as Vienna Standard Mean Ocean Water 

(VSMOW) (Gonfiantini, 1978). By convention, the 

value of VSMOW is 0 per mil. Oxygen-18 and deuterium ratios relative to VSMOW can be measured more 

precisely than absolute abundances. Analytical precision is generally within 0.05 per mil for δ18O (delta 

oxygen-18) and within 1.5 per mil for δD (delta deuterium) (Izbicki, 1996). 

Water that condenses at cooler temperatures 

(typically associated with higher altitudes, cooler 

climatic regimes, or higher latitudes) is lighter (more 

negative) than water that condenses at warmer temperatures (typically associated with lower altitudes, 

warmer climatic regimes, or lower latitudes). In addition, water that has been partly evaporated is enriched 

by fractionation of the heavier isotopes relative to its 

original composition. On graphs of δ18O and δD, partly 

evaporated water samples plot to the right of the meteoric water line along a line known as the evaporative 

trend line. As a result, the δ18O and δD composition of 

a water sample can provide a record of the source and 

evaporative history of the water. 

Tritium and carbon-14 samples were collected to 

help identify the age of water. Tritium (3H) is a naturally occurring radioactive isotope of hydrogen that has 

a half-life of about 12.4 years. In this study, the activity 

of tritium was measured in picocuries per liter (pCi/L); 

1 pCi/L is equivalent to about 2.2 disintegrations of tritium per minute or about one tritium atom in 

3.1 Z 1017 atoms of hydrogen. Prior to 1952, tritium 

activity in precipitation in coastal southern California 

was about 6 pCi/L. As a result of atmospheric testing of 

nuclear weapons from 1952 to 1962, tritium activity 

increased to greater than 2,000 pCi/L (Michel, 1976). 

Tritium concentrations and decay-corrected values in 

precipitation at Los Angeles, California, were calculated using techniques described by Michel (1989), 

(fig. 4). Because tritium can be part of the water molecule, tritium is not affected by reactions other than 

radioactive decay; therefore, tritium is an excellent 

tracer of the movement of water on time scales ranging 

from 10 to about 50 years before present. Ground water 

having tritium activities less than the detection limit of 

0.3 pCi/L is considered to have been recharged before 

1952. Ground water having measurable tritium activity 

is considered to be recharged after 1952. 

Carbon-14 (14C) is a naturally occurring radioactive isotope of carbon that has a half-life of about 5,730 

years. Carbon-14 data are expressed as percent modern 

carbon by comparing 14C activities to the specific activity of National Bureau of Standards oxalic acid (12.88 

disintegrations per minute per gram of carbon in 1950 

equals 100 percent modern carbon). 

Carbon-14 is not part of the water molecule and 14C 

activities can be affected by chemical reactions 

between dissolved constituents and aquifer material. 

Carbon-14 is a tracer of the movement and relative age 

of water on time scales ranging from several hundred to 

more than 20,000 years before present. 

Field parameters such as specific electrical conductance, pH, and dissolved oxygen were measured for 

both surface-water and ground-water samples in the 

field using probes calibrated with appropriate standards. Alkalinity was determined in the field by titration with a dilute sulfuric acid. All field measurements 

were made in accordance with the National Field Manual for the Collection of Water-Quality Data (Wilde 

and Radtke, 1998). The techniques used for the collection and processing of inorganic constituents were 

made in accordance with Horowitz and others (1994). 

Analyses for inorganic constituents were done by the 

U.S. Geological Survey National Water Quality Laboratory using techniques described by Fishman and 

Friedman (1989), Fishman (1993), Patton and Truitt 

(1992), and Struzeski and others (1996). 

Previous Investigations 

Many investigations have been made since the 

early 1900’s in the upper Santa Ana River drainage 

basin and, in particular, in the adjacent San Bernardino 

area (fig. 2). Several previous investigators have 

included parts of the Yucaipa area on the periphery of 

their study, but most have described only generalized 

Introduction 7 
data and concepts for the Yucaipa area. Such generalized information includes description of the regional 

hydrology (Mendenhall, 1905), estimation of groundwater-storage capacity (Eckis, 1934), calculation of 

ground-water outflow from the Yucaipa area (Dutcher 

and Burnham, 1959; Burnham and Dutcher, 1960), 

depiction of ground-water levels and susceptibility of 

liquefaction during a major earthquake (Matti and 

Carson, 1991), and evaluation of regional watermanagement options (California Department of Water 

Resources, 1970, 1979, 1986). 

The more detailed investigations in the Yucaipa 

area have focused on surficial geology and groundwater quantity. Surficial geology of the area has been 

mapped at a scale of 1:48,000 by Morton (1974) and 

more recently at a scale of 1:24,000 by Matti and others 

(1992). A detailed calculation of ground-water outflow 

from the area south of the Crafton Hills was made by 

Dutcher and Fenzel (1972). Sustainable yield of the 

ground-water basin was calculated by Mann (1986) 

and later by Todd (1988), and an explanation of the differences between the two yield calculations was made 

by Mann and Todd (1990). The potential for artificial 

recharge was evaluated by Moreland (1970). Changes 

in ground-water levels were summarized by Fletcher 

(1976) and Fox (1987), and a plan to monitor groundwater levels for much of the Yucaipa area was proposed 

by Fox (1990). A ground-water-flow model was developed for the upper part of the Oak Glen Creek drainage 

by Powers and Hardt (1974). Water-management plans 

were prepared for the Western Heights Water District 

(Egan and Associates, Inc., 1989) and for the Yucaipa 

Valley Water District (Camp, Dresser, and McKee, 

1994). 

Measurements of surface-water discharge in the 

Yucaipa area are scant. A much greater number of 

ground-water-level measurements are available for 

many wells in the area, including historical data that 

span several decades. Measurements of water quality 

for both surface water and ground water are made routinely to ensure that drinking-water standards are met. 

Other measurements of water chemistry, such as isotopic concentrations of hydrogen and oxygen, had not 

been made prior to this study. 

Acknowledgments 

The authors thank the San Bernardino Valley 

Municipal Water District for providing cooperative 

funding for this project. Also, we thank several 

individuals in the Yucaipa area—in particular, Joseph 

B. Zoba, John “Jack” Nelson, Brent J. Anton, and 

Frank E. Jubula with the Yucaipa Valley Water District; 

E. Bernice Long, previously with the Western Heights 

Water District; and Michael L. Huffstutler, previously 

with the City of Redlands—who greatly aided us in 

obtaining and understanding field data. We thank U.S. 

Geological Survey colleagues Jonathan C. Matti for 

providing geologic map data and Kelly R. McPherson 

for creating a geographical information system that 

aided in analysis of data and preparation of map figures. We also thank the several individuals who helped 

review and prepare the report, including Alan Welch 

(review), Jim Bowers (review), Larry G. Schneider 

(illustrations), Jerrald A. Woodcox (editing), and James 

B. Baker (layout and publication). 

DESCRIPTION OF STUDY AREA 

Physiography 

The study area is bordered on the west by the 

Crafton Hills, on the east by the Yucaipa Hills, on the 

north by the San Bernardino Mountains, and on the 

south by the badlands (fig. 2). Between the hills and 

mountains is a gently sloping area of unconsolidated 

deposits, commonly referred to as the Yucaipa plain or 

the Yucaipa ground-water basin. On the northwest side, 

the plain merges into the San Bernardino valley, and on 

the southeast side, the plain opens to the San Gorgonio 

Pass. The Yucaipa plain ranges in altitude from about 

1,800 to 3,600 ft above sea level. The hills and mountains surrounding the plain range in altitude from about 

3,000 ft in the Crafton Hills, to 5,000 ft along the ridge 

of the Yucapia Hills, to more than 8,000 ft in the San 

Bernardino Mountains. 

Population and Climate 

The study area includes parts of San Bernardino 

and Riverside Counties and the major cities of Yucaipa 

and Calimesa (fig. 3). In 1998, the population in the 

Yucaipa study area was about 38,200. Most residents in 

the area live on the plain, but many live in the surrounding foothills. Recent residential development is concentrated on the east side of Crafton Hills, on the 

Yucaipa Hills, and along the lower altitudes of the San 

Bernardino Mountains. 

8 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
Climate in the study area is moderate with long, 

dry summers and short, wet winters. On the plain, summer temperatures range from about 60 to 100 oF and 

winter temperatures range from about 40 to 70 oF. 

Annual precipitation in this semiarid region averages 

about 18 in/yr on the plain, and as much as 40 in/yr in 

the San Bernardino Mountains (Todd, 1988). Precipitation falls almost exclusively as rain on the plain; snow 

is the predominant precipitation above an altitude of 

about 6,000 ft. Snowpack in the San Bernardino Mountains commonly lasts into April and, occasionally, May. 

Geology 

Bedrock, which forms the hills and mountains 

that surround the Yucaipa plain on the north, east, and 

west sides, is composed mostly of crystalline igneous 

and metamorphic rocks of Cenozoic to Mesozoic age 

(fig. 5). These basement rocks consist predominantly of 

granodiorite, although granite, quartz monzonite, 

tonalite, dioritic gneiss, and schist also are present 

(Matti and others, 1992). Basement rocks in the 

Yucaipa Hills are cataclastically deformed and contain 

abundant fractures and intruded quartz veins. Some 

sedimentary rocks, mostly sandstone, mantle part of 

the crystalline bedrock in the vicinity of Mill Creek. 

The badlands to the south consist of poorly to moderately consolidated continental deposits of Pleistocene 

and Pliocene age that have been uplifted and dissected. 

In the badlands, the deposits consist of alternating beds 

or lenses of gray, yellow, or brown gravel, sand, silt, 

and clay. The gravel is predominantly from granitic 

rocks but contains numerous fragments of metamorphic and volcanic rocks. These badland deposits are cut 

by numerous faults and in places are gently to intensely 

folded. 

Between the San Bernardino Mountains and the 

badlands is a down-dropped block of crystalline rocks 

bounded on either side by the San Andreas Fault and 

the San Jacinto Fault (fig. 2). Erosion of the hills and 

mountains that surround the Yucaipa area has filled this 

tectonically created trough, called a graben, with alluvial deposits that are as much as 1,500 ft thick. The 

alluvial deposits are composed of several units ranging 

in age from late Pleistocene (very old alluvium) to 

Holocene age (recent alluvium) (fig. 5). The very old or 

older alluvium unconformably overlies most of the 

basement rocks. These alluvial deposits are both of late 

Pleistocene age and consist of boulders, gravel, sand, 

silt, and clay. Subsequent erosion of these moderately 

to well-consolidated deposits has resulted in deeply 

incised streambeds such as the channels of Oak Glen 

and Yucaipa Creeks. Isolated deposits of slightly consolidated younger alluvium border parts of the stream 

channels and badlands. Unconsolidated recent alluvium is present in stream channels throughout the 

Yucaipa plain and has its greatest width in the Western 

Heights subbasin. 

The geologic structure and landforms in the 

Yucaipa area are mostly a result of regional tectonism. 

To the north, the San Andreas Fault separates two tectonic plates—the North American Plate on the east and 

the Pacific Plate on the west (Harden, 1998, fig. 1–4). 

In addition to creating the sediment-filled graben that 

forms the Yucaipa ground-water basin, the structural 

forces associated with plate tectonics have caused several additional faults, some of which are visible at the 

land surface. One set of visible faults is subparallel to 

the northwest-trending San Andreas and San Jacinto 

Faults and includes the Banning and Oak Glen Faults; 

another set is nearly perpendicular to the first and 

includes the Chicken Hill Fault (fig. 5). Numerous 

additional barriers, which are hypothesized to be faults, 

have been inferred by geophysical and ground-waterlevel data. 

Hydrology 

The Yucaipa area is within the upper part of the 

Santa Ana River drainage basin and encompasses much 

of the San Timoteo Creek drainage (figs. 1 and 2). 

Although surface-water drainage is well defined to the 

north in the San Bernardino Mountains, the drainage 

becomes progressively less defined to the south in the 

more extensively eroded badlands. The Yucaipa area is 

drained by three primary streams: Wilson and Oak 

Glen Creeks, which flow from the San Bernardino 

Mountains, and Yucaipa Creek, which flows from the 

Yucaipa Hills (fig. 3). These streams coalesce and flow 

into San Timoteo Creek, which exits the area to the 

southwest (fig. 2). 

The semiarid conditions in the Yucaipa area limit 

the quantity and frequency of streamflow. Generally, 

streamflow is present in the middle and lower reaches 

of Wilson, Oak Glen, and Yucaipa Creeks only for brief 

periods after rain. Flow in the upper reaches of Oak 

Glen Creek is perennial as a result of ground-water discharge from Ford Canyon in the San Bernardino Mountains (fig. 3). Some of this flow is diverted for public 

supply. Just upstream from the Casa Blanca Barrier 

Description of Study Area 9 
Figure 5. Surficial geology of the Yucaipa area, southern California. 

10 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
(fig. 5), streamflow infiltrates into the unconsolidated 

deposits of the Yucaipa plain. In some places, flow in 

San Timoteo Creek is now perennial as a result of agricultural and urban runoff. 

The unconsolidated deposits of the Yucaipa 

plain—the recent, younger, older, and very old alluvium (fig. 5)—constitute the primary source of ground 

water in the area and together compose the valley-fill 

aquifer. Permeability of these deposits ranges from 50 

to 300 (gal/d)/ft2 (Burnham and Dutcher, 1960, p. 80). 

Recent river-channel deposits, especially near the hills 

and mountains, appear to be unweathered and very permeable, but most are above the water table. Most 

ground water occurs in the older, moderately consolidated alluvium at minimum depths of about 200 ft 

below land surface. Although the base of the valley-fill 

aquifer is unknown, it probably is more than 1,500 ft 

below land surface in most parts of the Yucaipa plain. 

In the western part of the plain, ground water historically was under artesian conditions, which may indicate the presence of fine-grained material of lower 

permeability within the valley-fill aquifer. 

For the most part, the crystalline rocks of the surrounding hills and mountains and underlying the 

valley-fill aquifer are poorly permeable. However, the 

multi-directional tectonic forces in the Yucaipa area 

have created highly fractured, cataclastic rock, which 

in some places is moderately permeable. Some wells, 

including large municipal wells, have been completed 

in the crystalline rocks in order to increase well yield. 

Faults are important not only because of their 

influence on the general topography, but also because 

of their influence on the flow of ground water. Fault 

zones in consolidated rocks commonly consist of fissures that may serve as conduits for ground-water flow. 

Conversely, faults that transect permeable unconsolidated materials may produce barriers to ground-water 

flow. For example, the San Andreas Fault along the 

base of the San Bernardino Mountains is known to be a 

barrier to ground-water flow because its trace in the 

alluvium at the mouth of nearly every canyon is marked 

by springs and dense vegetation. Although the barrier 

effects displayed by faults are not completely understood, the presence of offset beds, gouge material, 

sharp folds, and chemical cementation are suspected to 

contribute to reduced permeability. 

On a basinwide scale, the general movement of 

both surface water and ground water is southward and 

westward from the surrounding hills and mountains. 

On a local scale, however, the movement of ground 

water is more complex. Faults in the area divide the 

ground-water basin into several subbasins (Moreland, 

1970), which previous investigators have characterized 

as being relatively isolated from one another (fig. 6). 

Flow in and between subbasins is complex and is not 

well understood except as can be inferred from contour 

maps of ground-water levels (Moreland, 1970, figs. 

6–8; Todd, 1988, fig. 11). This lack of understanding of 

ground-water movement was a major impetus for this 

water-quality study, in particular for the collection of 

isotopic data. 

Detailed ground-water-level maps for different 

time periods, possibly corroborated by results from a 

ground-water flow model, are needed to better understand the flow between subbasins and to help interpret 

water-quality data. As a starting point, however, 

ground-water-level data from spring 1997 were 

obtained from local water agencies (fig. 6 and table 1). 

On the basis of these data and ground-water-level maps 

from Moreland (1970), ground water in the 

Triple Falls Creek subbasin (fig. 6) appears to flow 

from the east to the west toward the north end of 

Crafton Hills. In the Wilson Creek and Crafton subbasins, ground water flows generally from north to south. 

In the Calimesa subbasin, ground water flows from east 

to west, toward the San Bernardino area. Insufficient 

data were available in the Western Heights subbasin to 

determine the direction of ground-water flow, but in the 

past (1930–70), a pumping depression was present near 

Dunlap Acres (Moreland, 1970). 

Land Use 

Originally, the Yucaipa area was inhabited by 

Native Americans, and the name “Yucaipa” is derived 

from the Serrano Indian word “Ucipe,” which means 

wet and sandy. Until the early 1800’s, the area was 

under Spanish rule as part of the San Bernardino Rancho. By 1860, the land was privately owned by a few 

families. In the early 1900’s, part of the area was subdivided into apple orchards, and the area became synonymous with red apples. 

After 1940, the Yucaipa area became extremely 

popular as a retirement destination. Many mobilehome parks were built, mostly along the upper part of 

the Yucaipa plain near the San Bernardino Mountains. 

Rural-type residential development continued to be 

popular and covered much of the central part of the 

Yucaipa plain. As more of the area was urbanized, cultivation of citrus was moved to the edges of the plain, 

Description of Study Area 11 
Figure 6. Ground-water levels at selected wells in the Yucaipa area, southern California, spring 1997. 

12 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
Table Location and characteristics of selected surface-water sites and wells in the Yucaipa area, southern California.

[YVWD, Yucaipa Valley Water District; WHWD, Western Heights Water District; SMWD, South Mesa Water District; LSD, land-surface datum; ft, foot; na, not appl

Altitude of water 

Other well Altitude table Depth 

Site name or State well number Well owner identifiers Latitude Longitude of LSD (ft above (

(ft) sea level)1 

Description of Study Area 

Upper Oak Glen Creek in Ford Canyon na na 340326 1165605 5,920 na Oak Glen Creek in Ford Canyon na na 340320 1165612 5,560 na Oak Glen Creek near Oak Glen na na 340307 1165621 3,550 na Oak Glen Creek at 2nd street na na 340238 1170232 2,620 na Yucaipa Creek at Mesa Grande Bridge na na 340051 1170026 2,880 na Yucaipa Creek at 5th street na na 340049 1170314 2,390 na Yucaipa Creek below Dunlap Acres na na 340037 1170643 1,880 na Mill Creek at Yucaipa Regional Park na na 340316 1170251 2,630 na 1S/1W-19G1 YVWD YVWD # 31 340415 1170127 3,086 2,883 1S/1W-27L1 YVWD YVWD # 25 340312 1165839 3,875 — 1S/1W-32C1 YVWD YVWD # 13 340253 1170027 3,194 3,177 1S/2W-24C2 YVWD YVWD # 51 340438 1170242 2,695 2,610 1S/2W-25A1 YVWD YVWD # 37 340343 1170212 2,780 2,584 1S/2W-25R4 YVWD YVWD # 53 340255 1170216 2,730 2,458 1S/2W-34N1 City of Redlands — 340202 1170502 2,157 1,790 1S/2W-36G1 YVWD YVWD # 46 340236 1170231 2,623 — 12S/1W-08F1 YVWD YVWD # 27 340054 1170029 2,878 2,819 2S/1W-15F2 YVWD YVWD # 61 340003 1165825 3,515 — 2S/2W-01J1 YVWD YVWD # 50 340124 1170213 2,600 2,284 2S/2W-02M1 YVWD YVWD # 11 340129 1170351 2,401 2,141 2S/2W-03E1 WHWD WHWD # 6 340148 1170454 2,170 1,794 2S/2W-03L1 City of Redlands Chicken Hill 340129 1170442 2,200 2,096 2S/2W-04G3 WHWD WHWD # 2A 340144 1170536 2,100 1,779 2S/2W-04G4 WHWD WHWD # 11 340137 1170535 2,080 — 12S/2W-04J2 WHWD WHWD # 5A 340135 1170516 2,095 1,773 12S/2W-04R1 WHWD WHWD # 9 340120 1170513 2,091 1,753 2S/2W-10B2 City of Redlands Hog Canyon #2 340106 1170450 2,180 2,105 2S/2W-11A1 YVWD YVWD # 24 340105 1170316 2,446 2,146 2S/2W-11D1 YVWD YVWD # 10 340057 1170406 2,327 2,129 2S/2W-14C1 SMWD SMWD # 2 340014 1170343 2,393 2,167 2S/2W-14R3 SMWD SMWD # 4 335924 1170317 2,340 — 12S/2W-24L1 YVWD YVWD # 48 335848 1170243 2,327 — 12S/2W-28C2 Fisherman's Retreat — 335829 1170552 1,943 — 

1 13 Altitude of water levels provided by water districts for spring 1997. 
Figure 7. Land use in the Yucaipa area, southern California, 1990. 

14 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
Figure 7—Continued. 

Description of Study Area 15 
and since about 1990, most of the citrus groves have 

been replaced with planned residential developments. 

As of 1990, land use in the Yucaipa area was a 

combination of residential land covering much of the 

Yucaipa plain, and isolated pieces of agricultural land 

(fig. 7). The central part of the plain continues to be 

filled with small, older homes occupying as much as an 

acre of land. Mobile-home parks continue in their same 

location along the northern part of the plain. Recently 

constructed tract housing, at densities of 1 to 6 homes 

per acre, extends to the edges of the plain and onto the 

surrounding hills. Within the boundaries of the Yucaipa 

Valley Water District, which covers most of the plain, 

rural residential housing (less than or equal to 1 dwelling unit per acre) accounts for 35 percent of the land 

use, low-density residential housing (1 to 4 dwelling 

units per acre) accounts for 21 percent, and planned 

residential development (mixed residential, public 

land, and some commercial use) accounts for 

29 percent (Camp, Dresser, and McKee, 1994). 

The small amount of commercial development in 

the Yucaipa area is located along a few main streets, 

and there is almost no industrial development. Apple 

growing is still popular on the lower slopes of the San 

Bernardino Mountains, particularly along Oak Glen 

Creek, and each fall many visitors attend the apple harvest festival. The Yucaipa Regional Park, with its small 

lakes and grassy areas, is located on the northwest side 

of the Yucaipa plain adjacent to Crafton Hills. The 

small lakes are sustained by water imported from Mill 

Creek. On Wilson Creek, a large artificial-recharge 

basin has been constructed and can be used to recharge 

both local runoff and water imported from Mill Creek. 

Water Use 

Prior to the late 1800’s, the water supply of the 

Yucaipa area was limited to surface flow in the mountain streams and small quantities of springflow along 

the Chicken Hill Fault. In the 1890's and early 1900's, 

a number of flowing wells were completed in the Western Heights subbasin. At that time, several water companies were formed to distribute water for irrigation. 

Agricultural development during the period 1900–30 

required the installation of more wells throughout the 

area. By the 1930’s, this increased pumping had lowered the hydraulic head in the valley-fill aquifer to 

below land surface. This gradual decline in groundwater levels continued until the post-World War II 

development boom began in 1945. A combination of 

increased pumpage and reduced recharge caused by 

below-normal precipitation resulted in an increased 

rate of decline in ground-water levels of 10 to 20 ft/yr. 

This rate continued into the early 1960's and then 

decreased to 5 to 10 ft/yr (Moreland, 1970). Because 

population predictions indicate that local water needs 

will increase sharply over the next decade, it is likely 

that ground-water levels will continue to decline in 

some parts of the Yucaipa area. 

WATER QUALITY 

Water samples were collected from selected surface-water sites and wells in the Yucaipa area during 

1996–98. These sites and wells are shown in figure 3 

and listed in table 1. Results of chemical analyses of 15 

surface-water samples from 8 sites on 3 creeks and of 

32 ground-water samples from 25 wells are given in 

tables 2 and 3, respectively, in the back of this report. 

On the basis of these data, the major-ion composition 

of water was evaluated using Stiff (polygon) and Piper 

(trilinear) diagrams (figs. 8 and 9). A Stiff diagram 

shows the relative abundance of cations and anions 

expressed in milliequivalents per liter and plotted on 

one of four parallel horizontal axes (Stiff, 1951). The 

resulting polygon shows similarities or differences in 

general water chemistry, and the width of the polygon 

is an approximation of the total ionic content. A Piper 

diagram (Piper, 1944) shows the relative contribution 

of major cations and anions, on a charge-equivalent 

basis, to the total ionic content of the water. Percentage 

scales along the sides of the diagram indicate the relative concentrations, in milliequivalents per liter, of each 

major ion. Cations are shown in the left triangle, anions 

are shown in the right triangle, and the central diamond 

integrates the data. 

Surface Water 

Oak Glen, Yucaipa, and Mill Creeks were 

selected for the collection of water-quality samples. 

Four sites were located on Oak Glen Creek, in downstream order: two sites in Ford Canyon, one site near 

the town of Oak Glen, and one site at the Second Street 

crossing, just downstream from the confluence with 

Wilson Creek. Three sites were chosen on Yucaipa 

Creek, in downstream order: at the Mesa Grande 

bridge, at the Fifth Street bridge, and southwest of 

Dunlap Acres downstream from the confluence with 

16 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
Oak Glen Creek (fig. 3). One sample was collected at 

Yucaipa Regional Park where water from Mill Creek is 

imported to the park in a pipeline. The water in the 

pipeline originates as diversions from two locations on 

Mill Creek. The upper diversion is located in the 

incised drainage channel and is used as inflow to a 

powerhouse; the lower diversion is under the Highway 

38 bridge (fig. 3). 

The winter of 1997–98 was much wetter than 

average because of El Niño conditions. This weather 

pattern is caused by warming of the tropical Pacific 

Ocean and can result in extreme weather throughout 

the world and greater than average precipitation in 

southern California. As a result of El Niño conditions, 

February 1998 was the wettest February on record in 

southern California. Late-season storms typically come 

from the Pacific northwest, but also may result from 

warm, moist air drawn into southern California from 

the southwest. This latter effect produces many of the 

larger magnitude and longer duration storms. 

Storms differ in magnitude, duration, intensity, 

and direction—each of which may produce changes in 

water chemistry. In February 1998, three storms were 

sampled. From the many precipitation stations in the 

Santa Ana River drainage basin, nine were chosen to 

show storm patterns (fig. 10). The first storm entered 

the basin from the west and started producing rain at 

Carbon Canyon Dam (CCYN). The rain started falling 

at about 0700 (local time) on February 3, was basinwide in about 6 hours, and lasted about 16 hours. The 

greatest precipitation, 2.3 in., was recorded at Prado 

Dam (PRDO). The least precipitation, about 0.5 in., fell 

at higher altitudes in the mountains to the northeast of 

the study area at Converse Fire Station (CONV). Lower 

altitudes to the north and east of Yucaipa received 

approximately 2.0 in. of rain, as recorded at the Oak 

Glen station (OAKG). 

The second storm was the smallest and entered 

the basin from the west and then moved eastward. Rain 

began falling in the western end of the Santa Ana River 

drainage basin during the morning of February 19 and 

moved into the rest of the basin starting at about 2000. 

The greatest precipitation, 0.8 in., was recorded at 

OAKG; the least was 0.1 in. at CONV. 

The third storm was the largest and started in the 

mountains to the north. This storm is typical of an El 

Niño-influenced storm whereby tropical moisture from 

the southwest is entrained in a slow-moving, lowpressure system moving in from the northwest. The 

precipitation generally fell in two distinct periods( 

except at the Devore Fire Station (DEVO) and San 

Antonio Dam (SNTO) stations, both of which recorded 

nearly constant rainfall (fig. 10). The first rain fell in the 

afternoon of February 22, and the rest fell in the early 

evening of February 23. The precipitation was greatest 

in the mountains to the north: 6.3 in. at DEVO; 5.2 in. 

at SNTO; and 4.5 in. at OAKG. The precipitation was 

least, about 1.9 in., in the southern part of the basin at 

the Santa Ana River at Fifth Street (SAR5) and at Lake 

Mathews (LKMA). 

Storm runoff flows quickly out of the surrounding hills and mountains onto the plain with little time 

for the water to dissolve minerals and salts. As a result, 

water-quality samples from Yucaipa Creek had very 

low concentrations of dissolved solids, cations, and 

anions. At the two upstream sites, the concentration of 

dissolved solids (residue on evaporation) ranged from 

40 to 57 mg/L (milligrams per liter) (table 2, at back of 

report). Calcium and bicarbonate, although low in concentration, were the dominant ions on the basis of milliequivalents (fig. 8). 

The chemistry of Oak Glen Creek and Yucaipa 

Creek was similar in that water samples were dominated by calcium and bicarbonate ions. However, concentrations of sodium, magnesium, and sulfate were 

higher in samples from Oak Glen Creek. (fig. 8, table 

2). Dissolved-solids concentrations also were higher in 

Oak Glen Creek, ranging from 74 to 249 mg/L (table 

2). The higher concentrations of these constituents may 

result simply from the source of the water. Oak Glen 

Creek has its source in the San Bernardino Mountains 

and is perennial in the foothills, whereas the source for 

Yucaipa Creek is in the Yucaipa Hills. Samples collected during base flow in Oak Glen Creek near Oak 

Glen contained higher concentrations of ions than samples collected during stormflows (fig. 8). Calcium 

concentrations ranged from 24 to 45 mg/L in base-flow 

samples, and from 13 to 30 mg/L in stormflow samples. 

Dissolved-solids concentrations ranged from 120 to 

249 mg/L during base flows, and from 74 to 227 mg/L 

during stormflows. Concentrations of other major ions 

also decreased during stormflows (fig. 8, table 2). This 

decrease in concentrations probably results from dilution of base flow with stormflow having a lower ionic 

strength. 

The highest concentration of major ions in 

Yucaipa Creek was found at the downstream site, 

located below the confluence with Oak Glen Creek 

where the surface water exits the study area southwest 

of Dunlap Acres (figs. 8 and 9A). The dissolved-solids 

Water Quality 17 
Figure 8. Water chemistry in samples from selected wells and surface-water sites in the Yucaipa area, southern California. 

18 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
Figure 8—Continued. 

Water Quality 19 
100 

80 

60 

40 

20 

0 

100 

80 

60 

40 

20 

0 

100 

80 

60 

40 

20 

0 

100 

80 

60 

40 

20 

0 

20 

40 

0 

60 

80 

100 

100

80

60

40 

20

0

0 

20 

40 

60 

80 

100 

80 

60 

100 

40 

20 

0

60 

80

100

20

40

0 

100 

80 

60 

40 

20 

0 

CALCIUM 

CALCIUM

PLUS

MAGNESIUM

SULFATE PLUS CHLORIDE 

SODIUM

PLUS

POTASSIUM

MAGNESIUM 

CHLORIDE, FLUORIDE, NO2 + NO3 

SULFATE

CARBONATE PLUS

BICARBONATE 

PERCENTAGE OF TOTAL MILLIEQUIVALENTS PER LITER 

A 

EXPLANATION 

Below� 

Dunlap� 

Acres 

Oak Glen Creek - Base flow Mill Creek - Base flow 

Oak Glen Creek - Stormflow Yucaipa Creek - Stormflow 

Below� 

Dunlap� 

Acres 

100 

80 

60 

40 

20 

0 

100 

80 

60 

40 

20 

0 

100 

80 

60 

40 

20 

0 

100 

80 

60 

40 

20 

0 

20 

40 

0 

60 

80 

100 

100

80

60

40 

20

0

0 

20 

40 

60 

80 

100 

80 

60 

100 

40 

20 

0

60 

80

100

20

40

0 

100 

80 

60 

40 

20 

0 

CALCIUM 

CALCIUM

PLUS

MAGNESIUM

SULFATE PLUS CHLORIDE 

SODIUM

PLUS

POTASSIUM

MAGNESIUM 

CHLORIDE, FLUORIDE, NO2 + NO3 

SULFATE

CARBONATE PLUS

BICARBONATE 

PERCENTAGE OF TOTAL MILLIEQUIVALENTS PER LITER 

B 

15F2 

24L1 

24L1 

14R3 

28C2 

1J1 

15F2 

28C2 

28C2 Abbreviated State well number 

1J1 

EXPLANATION 

Figure 9. Major-ion composition of (A) surface water and (B) ground water in the 

Yucaipa area, southern California. 

20 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
118A00' 117A30' 117A00' 116A30'


34A

15'


Santa 

Ana 

River 

San

Jac into River 

Lake� 

Elsinore 

Big Bear� 

Lake 

Temescal Wash 

SARM 

LKMA 

OAKG 

PRDO 

SNTO 

DEVO 

CONV 

CCYN 

SAR5 

Pacific� 

Ocean 

Santa Ana River� 

drainage basin 

Yucaipa� 

study� 

area 

0 10 20 MILES

0 0 20 KILOMETERS

1 (2.35) 

2 (0.8) 

3

(6.3) 

Precipitation station 

1

33A 

45' 

3.0 

First storm Sample period 

6.0 

2.5 5.0 

2.0 4.0 

1.5 3.0 

1.0 2.0 

0.5 1.0 

0.0 0.0 

Feb 2 Feb 3 Feb 4 Feb 22 Feb 23 Feb 24 

1.0 DATE 

Third storm 

Sample period 

(6.3) 

EXPLANATION 0.8 

Storm plots Station identifier and name 

CUMULATIVE PRECIPITATION, IN INCHES


Second storm Sample period 

0.6	 CCYN: 

CONV: 

DEVO: 

LKMA:

0.4	 OAKG: 

PRDO: 

SAR5: 

0.2 SARM: 

SNTO: 

0.0 

Feb18 Feb19 Feb 20 

DATE 

Carbon Canyon Dam 


Converse Fire Station


Devore Fire Station 


Lake Mathews near Corona


Oak Glen


Prado Dam


Santa Ana River (5th Street)


Santa Ana River near Mentone


San Antonio Dam


Figure 10. Precipitation stations and cumulative precipitation for three February 1998 storms in the Santa Ana River drainage basin, 

southern California (note change in vertical scale on graphs). Arrows on map show direction storm started in basin; numbers indicate storm 

sequence sampled and largest amount of total precipitation, in inches. Precipitation data from U.S. Army Corps of Engineers (Gregory 

Peacock, written commun., 1998). 

Water Quality 21 
concentration was slightly greater than 100 mg/L (table 

2). The Piper (trilinear) diagram for this surface-water 

sample shows that the dominant ions were mostly calcium and bicarbonate (fig. 9A). In comparison with the 

two upstream sites, this site had a much higher concentration of sulfate (22 mg/L compared to <3.2 mg/L) and 

a slightly higher concentration of chloride. The large 

differences in the concentrations of many constituents 

between the two upstream sites on Yucaipa Creek and 

the downstream site may be a result of runoff from Oak 

Glen Creek and the town of Yucaipa, or the differences 

may result from the larger discharge at the time of sampling of the downstream site (190 ft3

/s in comparison to 

2.3 ft3

/s). The sample taken at the downstream site was 

collected during the rising limb of the runoff which 

typically carries more sediment. 

As found in samples collected from Oak Glen 

Creek and Yucaipa Creek, the dominant ions in the 

sample collected from Mill Creek at the inlet to the 

Yucaipa Regional Park (site H) were calcium and bicarbonate (fig. 8). Most constituent concentrations, such 

as sodium, chloride, silica, phosphate, boron, and iron, 

were similar to concentrations in base-flow samples 

collected from Oak Glen Creek at site A and B in Ford 

Canyon (fig. 8 and table 2). These similarities would be 

expected because the source of the water in both creeks 

is the San Bernardino Mountains. Other constituents, 

such as calcium, magnesium, dissolved solids, and sulfate, had concentrations similar to those in stormflow 

(figs. 8 and 9; table 2). Lithium concentration [(5 Hg/L) 

micrograms per liter] was higher in the Mill Creek 

sample. 

In addition to Stiff and Piper diagrams, the 

major-ion composition of water samples was evaluated 

using boxplots. The variability of selected constituents 

as well as differences between surface and ground 

water can be observed from these boxplots (fig. 11). 

Boxplots show the range of values for a selected waterquality constituent. The vertical size of the box is determined by the range of the data, as in a histogram. The 

width of the box is meaningless and is for display purposes only. The median and selected percentiles of the 

data are indicated along with any outliers. 

Phosphate showed the highest variability (ranging from the upper 75 to the lower 25 percentile fig. 11) 

of any constituent sampled, perhaps as a result of the 

higher phosphate concentrations found in storm runoff 

in Yucaipa Creek (table 2). Nitrate (NO3) 

concentrations were low, ranging from 0.18 to 

2.3 mg/L as nitrogen. These low values indicate the 

lack of a significant source of nitrate from runoff under 

these conditions. The higher values of nitrate were 

found in samples collected downstream from the agricultural land adjacent to Oak Glen Creek and Yucaipa 

Creek (figs. 7 and 12). Organic ammonia values ranged 

from less than the detection limit of 0.1 mg/L to 

0.7 mg/L. More studies are needed to evaluate the rates 

at which species are converted to and from nitrate. 

Calcium concentrations ranged from 5.8 to 

45 mg/L. Chloride and fluoride concentrations ranged 

from 1.2 to 7.7 mg/L, and from 0.1 to 0.8 mg/L, respectively. Sulfate concentrations ranged from 1.4 to 

37 mg/L. Sodium concentrations ranged from 2.2 to 

15 mg/L. Iron and manganese concentrations ranged 

from less than the detection limit of 3 Hg/L to 

110 Hg/L, and from less than the detection limit of 

1 Hg/L to 15 Hg/L, respectively. Boron concentrations 

ranged from 7 to 24 Hg/L. Barium concentrations 

ranged from 4.3 to 20 Hg/L. All constituents were well 

below their respective maximum contaminant levels 

(MCL) (U.S. Environmental Protection Agency, 1994). 

Concentrations of dissolved oxygen in samples 

collected during the summer from Mill and Oak Glen 

Creeks were 8.2 and 8.5 mg/L, respectively. Dissolvedoxygen concentrations in winter samples from Oak 

Glen and Yucaipa Creeks ranged from 9.4 to 

10.8 mg/L. Lower dissolved-oxygen concentrations in 

the summer samples may result from less turbulence in 

the river than during winter stormflow, and may result 

from the lower solubility of oxygen in warmer water. 

Also in summer, dissolved oxygen can be depleted by 

biochemical processes, such as respiration by algae 

that consume dissolved, suspended, or precipitated 

organic matter. 

Ground Water 

Ground-water samples were collected from 25 

wells mostly on the Yucaipa plain (fig. 3) and from 1 

well in San Timoteo Canyon. On the basis of these 

samples, most ground water in the Yucaipa area shows 

little areal variability and is of good quality by U.S. 

Environmental Protection Agency (EPA) drinking 

water standards (U.S. Environmental Protection 

Agency, 1994). Dissolved-solids concentrations ranged 

22 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
0

0

Dissolved Residue on 

oxygen pH evaporation 15 10 600 

10 9 400 

Outlier value 

of 712 not 

shown

mg/L as N 

Outlier value 

of 200 not 

shown 

mg/L as P Hg/L as B mg/L as F mg/L as K STANDARD UNITS 

mg/L as Na mg/L 

mg/L as Mg mg/L 

5 8 200 

0 7 0 

SW GW SW GW SW GW 

Sodium Potassium Magnesium Calcium 

120 6 30 100 

80 4 20 

50 

40 2 10 

Outlier value 

of 260 not 

shown 

0 0 0 0 

SW GW SW GW SW GW SW GW 

Chloride Fluoride Sulfate 

40 2.0 100 

20 1.0 50 

0 0 0 

SW GW SW GW SW GW 

Barium Boron Iron Manganese 60 100 

Outlier value 

of 330 not 

shown 

150 

Outlier value 

of 2,300 not 

shown 

70 

40 100 50 

50 

30 

20 50 

10 

0 0 0 0 

SW GW SW GW SW GW SW GW 

Nitrite + Nitrate 

Lower detached 

Upper detached 

Median 

Upper outside 

Lower outside 

Phosphate 20 0.3 EXPLANATION

SW Surface-water samples 

GW Ground-water samples 

0.2 Upper 90 percent mg/L Milligrams per liter 

10 

Upper 75 percent Hg/L Micrograms per liter 

0.1 Lower 25 percent 

Lower 10 percent 

0 0 

SW GW SW GW 

Figure 11. Concentration of selected constituents for selected wells and surface-water sites in the Yucaipa 

area, southern California. 

mg/L as Mn mg/L as Ca 

mg/L as Ba mg/L as Cl 

Hg/L as Fe mg/L as SO4 

Water Quality 23 
Figure 12. Concentration of dissolved solids, nitrites plus nitrates, and dissolved oxygen for selected wells and surface-water sites in the 

Yucaipa area, southern California. 

24 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
Figure 12—Continued. 

Water Quality 25 
from 186 to 563 mg/L (table 3, at back of report; fig. 

12), with an outlier of 712 mg/L at well 

2S/2W-1J1. Sodium concentrations ranged from 14 to 

58 mg/L, with outliers of 120 mg/L and 200 mg/L at 

wells 2S/2W-28C2 and 2S/2W-1J1, respectively. Chloride concentrations ranged from 6.3 to 36 mg/L, with 

an outlier of 65 mg/L at well 2S/2W-28C2. Sulfate concentrations ranged from 13 to 86 mg/L, with an outlier 

of 260 mg/L at well 2S/2W-1J1. Iron concentrations 

ranged from less than the detection limit of 3 mg/L to 

140 mg/L, with an outlier of 2,300 mg/L, also at well 

2S/2W-1J1. This unusually high concentration of iron 

may result from corrosion of the steel well casing. The 

sample from well 2S/2W-1J1 also showed signs of a 

reducing environment and had no dissolved oxygen, a 

condition that causes iron to become soluble. Boron 

concentrations ranged from 20 to 70 Hg/L, with an outlier of 330 Hg/L at well 2S/2W-1J1. 

As in surface water, calcium and bicarbonate 

were the major ions found in ground water on the basis 

of milliequivalence (figs. 8 and 9B). Four wells were 

not dominated by calcium and bicarbonate. Water from 

well 2S/2W-1J1 was high in sodium, sulfate, and 

dissolved-solids concentration and contained almost no 

magnesium. Water from this well also had elevated 

concentrations of fluoride and boron, which may indicate a contribution of mineralized ground water emanating from a nearby fault zone. This explanation 

seems plausible because well 2S/2W-1J1 is located 

near the intersection of the South Mesa and Casablanca 

Barriers (figs. 3 and 8). Wells 2S/2W-14R3 and 

2S/2W-24L1 yielded water having more than 

80 percent sodium and potassium and less than 

20 percent calcium and magnesium (fig. 9B). These 

two wells are located south of the Banning and Cherry 

Valley Faults (figs. 3 and 8). Ground water moving to 

these wells probably has a geochemical signature more 

representative of the unconsolidated nonmarine sediment of the badlands than of the crystalline rocks found 

in the other hills and mountains in the Yucaipa area. 

Well 2S/2W-28C2 is located in San Timoteo Canyon, 

which is eroded into the badlands, and has the same 

water type as well 2S/2W-24L1 (fig. 9B). Well 

2S/2W-28C2 is located near and probably downgradient from fishing ponds. The elevated concentrations of 

sodium, calcium, chloride, and bicarbonate in water 

from this well may result from evaporative processes 

that occur in the ponds before water infiltrates into the 

ground. 

Three wells (1S/2W-34N1, 2S/2W-3E1, and 

2S/2W-4R1) located in the western part of the Yucaipa 

area and one well (1S/1W-19G1) in the northern part of 

the Yucaipa area yielded water with a high concentration of nitrate (fig. 12). Water from three of these wells 

(19G1, 34N1, and 3E1) had nitrate concentrations that 

exceed the MCL of 10 mg/L as N; water from well 

2S/2W-4R1 had a nitrate concentration of 9.6 mg/L, 

just below the MCL. Water from these four wells also 

was higher in dissolved solids, sodium, calcium, chloride, sulfate, and bicarbonate. These wells are located 

downgradient from an area that has been used for agriculture (fig. 7). The high concentrations of these constituents at well 1S/2W-34N1 may result from 

agricultural practices and evaporative processes. The 

lower concentrations of nitrate in wells 2S/2W-3E1 and 

2S/2W-4R1 may result either from a different source of 

nitrate or from dilution with less contaminated water as 

ground water moves through the area. The later seems 

more plausible, suggesting a separate but converging 

ground-water-flow path, possibly coincident with Oak 

Glen Creek. 

Most constituents analyzed in ground-water 

samples were below their respective MCL’s. All sulfate 

concentrations, except for well 2S/2W-1J1, were below 

the Secondary Maximum Contaminant Level (SMCL) 

of 250 mg/L, as defined by the U.S. Environmental 

Protection Agency (1994). Water from one well 

(2S/2W-1J1) exceeded the SMCL for iron, which is 

300 Hg/L. Water from two wells (1S/1W-19G1 and 

2S/2W-28C2) exceeded the SMCL for manganese, 

which is 50 Hg/L. Barium concentration in all water 

samples was far below the MCL of 2,000 Hg/L. 

In general, sodium, calcium, magnesium, chloride, nitrate, sulfate, and dissolved-solids concentrations were higher in ground water than in surface water 

(fig. 11) probably as a result of dissolution of minerals 

in the aquifer matrix. However, concentrations of iron, 

manganese, and phosphate were higher in surface 

water than in ground water. 

Flowmeter Data 

Flowmeter data were collected from well 

1S/2W-25R4 using a commercial, vertical-axis current 

meter, commonly called a spinner tool. This tool 

26 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
Water Quality 27

measures the velocity of water flowing inside the well 

casing by recording the number of revolutions per 

second made by a spinning impeller. Flowmeter data 

are helpful in determining the water-yielding characteristics of aquifer material opposite the screened interval 

and in evaluating mixtures of water collected at different depths within the well. A continuous profile of 

velocity was recorded for the entire depth of the well, 

and static data (stop counts) were collected every 10 ft.

Flowmeter data for well 1S/2W-25R4 demonstrate that water does not enter the well in a uniform 

manner (fig. 13). Rather, the data suggest that there are 

three distinct zones. About one-half of the total discharge from the well entered the casing through the top 

150 ft of perforations—that is, between depths of 450 

and 600 ft below land surface. The rest of the discharge 

entered the well at a nearly uniform rate between 

depths of 600 and 820 ft. Virtually no water entered the 

well between depths of 820 and 950 ft. Because the 

water table was at a depth of about 300 ft below land 

surface, it is likely that some additional contribution of 

water to the well would have occurred if the well were 

perforated above a depth of 450 ft.

Variations in water yield can be caused by many 

factors such as the hydraulic characteristics of adjacent 

aquifer material or any encrustation of the well screen. 

The inferred change in aquifer characteristics at about 

600 ft is not evident from the driller’s or electric logs, 

but the change at 820 ft is supported by a change in signature of the 16-inch normal resistivity log (fig. 13). 

The material below 820 ft appears to have thinner layering and a higher percentage of clay. These observed 

Figure 13. Driller’s log, electric logs, vertical flow rate, well construction, and water-quality sampling for well 

1S/2W-25R4 in the Yucaipa area, southern California.

Driller's

log

Driller's log Water-quality�

sampling depth

Well construction Water level�

DEPTH, IN FEET BELOW LAND SURFACE

Spontaneous

potential

16-inch

normal

resistivity

Vertical

flow rate

Well

construction

Waterquality

sampling

depth

(millivolts) (ohm-meters) (percent)

0

100

200

300

400

500

600

700

800

900

Blank casing

Point sample

Bulk sample

Static

Pumping

Pumping rate -�

750 gallons per�

 minute

Perforated�

casing

Pump intake

Direction of�

flow in well

1,000

-350 -150 0 250 0 100

Silt and sand

Gravel

Clay B

EXPLANATION

B

Tritium

(picocuries

per liter)

3.9�

<0.3�

0.4�

0.8

1.4

2.1
changes in flow rate and possible changes in lithology 

were used to select specific depths at which to sample 

water quality. 

Depth-Dependent Samples 

Depth-dependent and bulk samples for chemical 

and isotopic analyses were collected from production 

wells (table 3). Production wells generally have long 

screened intervals and can be open to more than one 

geologic or hydrogeologic unit. Bulk samples from 

production wells typically are a mixture of ground 

water from different units; nevertheless, only bulk samples were obtained for production wells sampled in this 

study, except for well 1S/2W-25R4, because of the 

expense and difficult logistics of depth-dependent sampling. 

At well 1S/2W-25R4, depth-dependent chemical 

and flowmeter data were collected using special sample-collection techniques while the well was pumped. 

All depth-dependent water samples and one bulk sample were collected while the production well was discharging at a rate of 750 gal/min. To facilitate this 

discrete-depth sampling, the well had been modified 

with a temporary, lower capacity pump. A second bulk 

sample was collected while the well was pumped at a 

rate of 1,450 gal/min using the standard-capacity production pump. Depth-dependent water samples were 

collected using a high-pressure hose equipped with a 

one-way valve that allows water to enter from a specific 

depth (Gossell and others, 1995; Izbicki and others, 

1999). The hose is lowered to the desired depth, the 

valve is opened, and the sample is collected. Then the 

hose is retrieved from the well, and the sample water is 

collected from the hose at land surface. Prior to sample 

collection, the well was pumped for over 12 hours to 

ensure that ground water entering the well through the 

screened interval was representative of the aquifer. 

All samples were collected below the pump 

intake. The sample collected from the deepest part of 

the screened interval is interpreted as representing 

water entering below that depth. Water sampled above 

the lowest sample depth and below the pump intake is 

a mixture of water in the well at the first sample depth 

and water that entered the well between the two sample 

depths. The proportions of water in that mixture can be 

determined from the flowmeter data. 

Results of the depth-dependent sampling show 

that the general water chemistry for the samples from 

well 1S/2W-25R4 are almost identical. Stiff diagrams 

of each sample collected at the different depths are similar to the Stiff diagram of the bulk sample shown in 

figure 8. This small vertical variability in general water 

chemistry can be explained in at least two ways. First, 

the geologic materials adjacent to the perforated intervals may be chemically similar despite their hydraulic 

differences (fig. 13). Second, ground water flowing in 

this recharge area near the mountains may not have had 

sufficient time to convert into chemically different, vertically stratified compositions. 

Some vertical differences, however, were noted. 

The dissolved-oxygen concentrations were highest 

near the water table and lowest at the bottom of the 

well. The concentration of nitrate and nitrite also 

decreased with depth. Dissolved-solids and chloride 

concentrations tended to peak in the middle depths of 

the well. These results suggest that the most active part 

of the ground-water flow system is near the top of the 

well. 

Tritium, a naturally occurring radioactive isotope of hydrogen, was used to determine the age (time 

since recharge) of the ground water. Tritium activity 

above the detection level of 0.3 pCi/L (picocuries per 

liter) was used as an indication of ground water 

recharged since 1952. Some processes that could affect 

tritium values are dispersion, mixing with different 

waters, and degassing during sampling. All depthdependent samples from well 1S/2W-25R4 were analyzed for tritium. The highest tritium value (3.9 pCi/L) 

came from the shallowest sample depth, indicating that 

at least some of this water was recharged since 1952 

(fig. 13). The other samples ranged from less than the 

detection limit of 0.3 pCi/L at 590 ft to 1.4 pCi/L 

(fig. 13 and table 3) at the bottom of the well. 

The presence of an elevated value of tritium at 

the bottom of the well is unlikely, because it implies 

that younger water is present at the top and bottom of 

the well. A more likely explanation is that the bottom 

of the well is inactive and was not purged of water during pumping. This explanation is consistent with the 

flowmeter data showing that virtually no water enters 

the well below a depth of about 820 ft. If this explanation is correct, then all water-chemistry data collected 

for depths at 820 and 900 ft represent largely unpurged 

water originating from shallower perforated intervals. 

28 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
--------------------

Tritium values for the bulk samples were 2.1 pCi/L for 

a pumping rate of 750 gal/min and 3.4 pCi/L for a 

pumping rate of 1,450 gal/min. The higher tritium 

value for the higher pumping rate indicates that more 

water is being withdrawn from the uppermost zone. 

Depth-dependent samples at the lower pumping 

rate (750 gal/min) also were analyzed for 14C (table 3). 

The collected water samples are relatively young given 

the time scale for waters dated using 14C. Expressed as 

percent modern carbon, the 14C value was 86.1 in the 

well where no tritium (< 0.3 pCi/L) was detected (fig. 

13). Assuming radioactive decay, with an initial 14C 

activity of 90 percent modern carbon (Izbicki and others, 1997, p. 16) and neglecting reactions with the aquifer material, this sample has an approximate time of 

recharge of less than 400 years before present. 

A simple three-cell mixing model can be used to 

test the data and interpretations of the depth-dependent 

sampling. If Q1, Q2, and Q3 are the discharge rates for 

the upper, middle, and lower zones, respectively; and 

C1, C2, and C3 are concentrations of a selected constituent for the same zones, then 

QT CT = Q1 C1 + Q2 C2 + Q3 C3, (1) 

where QT and CT are total discharge and concentration 

from the well. Using flowmeter and tritium 

data, 

750 (2.1) = 375 (3.9) + 375 (0) + 0 (1.4), or (2A) 

375%3.9& 2.1 ∼ 750 - , (2B) 

which suggests that the assumed contribution from 

each zone to total discharge is reasonable. Applying the 

same test to other constituents (alkalinity, sulfate, 

nitrate) yielded similar results. Additional depthdependent samples from nearby wells might help verify these results and extend analysis to other parts of the 

Yucaipa area. 

ISOTOPIC COMPOSITION OF WATER 

Oxygen-18 and Deuterium 

Surface-water isotopes at a particular site have a 

wide range of values (fig. 14A) which are highly influenced by the direction from which storms are generated 

and over time will approximate the values of ground 

water. Although all three storms originated in the northwest, the first and second storms entered the basin from 

the west and moved northeastward (fig. 10). The third 

storm entered the basin from the north and produced 

much more precipitation than did the first two storms. 

The third storm had warm moist air drawn into the system from the west. This effect typically occurs later in 

the rainy season and produces many of the larger magnitude, longer duration storms. Because the moist air 

from the storm is generated from a lower latitude and 

warmer climate than is air from the north, the precipitation is isotopically heavier (fig. 14). 

Isotopic values for base flow (table 2) plot 

slightly above the meteoric water line (fig. 14B), and 

mean isotope ratios are −10.3 and −69.0 for δ18O and 

δD, respectively. The mean isotopic ratios for the first 

storm are −12.7 and −91.8 for δ18O and δD, respectively. These values are grouped below the meteoric 

water line near the bottom of the graph and indicate that 

this runoff is isotopically much lighter than is base 

flow. The mean isotope ratios for the second storm are 

−11.7 and −77.3 for δ18O and δD, respectively, and are 

grouped above the meteoric water line and slightly 

below the middle of the graph. The mean isotopic ratios 

for the third storm are −6.51 and −38.2 for δ18O and 

δD, respectively, and are grouped above the meteoric 

water line, near the top of the graph. Runoff from this 

storm is isotopically much heavier than is base flow. 

Over time, the isotopic ratio of water vapor in 

different storms trends to an average value; therefore, 

the isotopic ratio of ground water is determined primarily by local differences in the temperature of condensation of water vapor, prior to its being recharged in 

different places and at different times. The deuterium 

content of precipitation varies seasonally as well as by 

storm and is highly dependent on storm- track trajectories (Friedman and others, 1992). The δ18O and δD 

ratios of water from most wells ranged from −8.11 

Isotopic Composition of Water 29 
A -20 

-30 

-40 

-50 

-60 

-70 

-80 

-90 

-100 

-110 

-14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 

Isotopic composition by site 

28C2 

(San Timoteo 

Canyon) 

in Ford Canyon 

near Oak Glen 

Upper Ford Canyon 

at 2nd Street 

at Mesa Grande 

at 5th Street 

below Dunlap Acres 

Ground-water sites 

Oak Glen Creek 

Yucaipa Creek 

Mill Creek outlet at Regional Park 

Meteoric water line

(Craig, 1961) 

Evaporative 

trend line 

Local ground-water line 

A� 

B� 

C� 

D 

E� 

F� 

G 

H 

DELTA OXYGEN-18 (δ 18O), IN PER MIL 

B -20 

-30 

-40 

-50 

-60 

-70 

-80 

-90 

-100 

-110 

-14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 

Isotopic composition by storm 

28C2 

(San Timoteo 

Canyon) 

Ground-water sites 

Base flow 

Stormflow 

February 3, 1998 

February 19, 1998

February 23, 1998 

Meteoric water line

(Craig, 1961) 

First storm 

Second storm 

Third storm 

Evaporative 

trend line 

Local ground-water line 

DELTA OXYGEN-18 (δ 18O), IN PER MIL 

Figure 14. Isotopic concentrations of delta deuterium (∂D) compared to delta oxygen-18 (∂18O) by site (A) and by 

storm (B) for selected wells and surface-water sites in the Yucaipa area, southern California. DELTA DEUTERIUM (δ D), IN PER MIL DELTA DEUTERIUM (δ D), IN PER MIL 

30 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
to −9.97 per mil and from −53.8 to −65.5 per mil, 

respectively, and the values are tightly grouped above 

the meteoric water line. The average δ18O and δD 

ratios of surface water samples was −10.2 and −68.3 

per mil which approximate ground-water values. The 

isotopic ratio of water from wells plots along a local 

ground-water line about 1 per mil above, and parallel 

to, the meteoric water line. Similar data from 

Woolfenden (1994) and Izbicki and others (1997) corroborate the local ground-water line for the western 

slope of the San Bernardino Mountains. Snow and, in 

turn, snowmelt have been shown to plot above the 

meteoric water line (Magaritz and others, 1989). The 

heaviest (least negative) water sampled, with respect to 

δ18O, is from well 2S/2W-28C2. Because the well is 

near fishing ponds, water moving to the well may have 

been partly evaporated prior to being recharged. An 

evaporative trend line can be drawn from well 

2S/2W-28C2 to a point that intersects the local groundwater line near the mean value (fig. 14). 

Tritium 

Tritium activity in water from wells (table 3 and 

fig. 15) in the Yucaipa area ranged from less than the 

detection limit of 0.3 to 15 pCi/L, and tritium activity 

in water from surface-water sites (table 2) ranged from 

7.3 to 18 pCi/L. Tritium activity in 27 of 31 well samples ranged from 0.7 to 15 pCi/L, indicating that all or 

part of the pumped water was recharged after 1952. 

Many of these wells are located on the Yucaipa plain 

and likely extract ground water from a water-bearing 

zone that is hydraulically connected to areas of recent 

recharge (fig. 15). Tritium activity in water from wells 

near the hills and mountains—in particular north of the 

Oak Glen Fault, or east of the Casa Blanca Fault and 

north of the South Mesa Barrier— ranged from 7.2 to 

11 pCi/L. These values are similar to surface-water 

samples, and probably indicate that most pumped 

water was recharged recently. 

Tritium activity in water from well 2S/2W-28C2 

was 7.8 pCi/L. The proximity of the well to the fishing 

ponds, as well as the general chemistry data and the 

anomalous δ18O and δD data, suggests that the ponds 

may be a source of recharge to the well. The tritium 

activity in water from well 2S/2W-3E1 was 15 pCi/L, 

the highest value found in ground-water samples. Well 

2S/2W-3E1 is located along Oak Glen Creek, which 

may be a source of recharge to the well. 

In water from wells 2S/2W-4G3, 2S/2W-4G4, 

and 2S/2W-4J2, tritium activity was less than the detection limit of 0.3 pCi/L. These wells are located at the 

west end of Yucaipa in the Western Heights subbasin 

and have the oldest water sampled. The depth of two of 

the three wells is greater than 1,000 ft (1,690 and 

1,090 ft), and the wells may be extracting a greater proportion of deeper, older ground water than other, shallower wells. The Western Heights subbasin, in 

particular Dunlap Acres, also historically had a pumping depression, which is caused by ground-water 

extractions exceeding recharge. The pumping depression, the absence of tritium, and the greater distance of 

this area from the greater precipitation found in the San 

Bernardino Mountains suggests that Dunlap Acres 

receives less recharge than other parts of the Yucaipa 

area. 

LIMITATIONS AND FUTURE NEEDS 

The primary limitation of this study is the small 

number of vertically discrete ground-water samples 

that were obtained. No multiple-depth monitoring 

wells were available in the Yucaipa area at the time of 

this study. Since sampling was done for this study, 

some multiple-depth monitoring wells have been 

installed. If these wells were sampled for the same 

chemical constituents, the data likely would aid in 

understanding the vertical and horizontal characteristics of ground-water flow in the Yucaipa area. Depthdependent sampling of production wells is logistically 

challenging, but can yield excellent flow and waterquality data to compare with water-level and waterquality data from multiple-depth monitoring wells. 

The second major limitation of this study is the 

lack of detailed, ground-water-level maps—ideally for 

different time periods and for each significant hydrogeologic unit in the Yucaipa area. Because areal and 

vertical ground-water-level data are sparse, and the 

arrangement of subbasins is complex, this mapping 

may need to be done iteratively with development of a 

ground-water flow model. 

Limitations and Future Needs 31 
Figure 15. Delta deuterium (δD), delta oxygen-18 (δ18O), and tritium activity in selected wells and surface-water sites in the Yucaipa area, 

southern California. 

32 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
Figure 15—Continued. 

Limitations and Future Needs 33 
SUMMARY AND CONCLUSIONS 

Most water sampled in the Yucaipa area is a 

calcium-bicarbonate type. The general chemical composition of surface water resembles that of ground 

water, although the concentrations of most constituents 

are higher in ground water. The ionic strength of most 

ground-water samples was similar. Elevated concentrations of nitrate were found in some ground-water samples from wells and may indicate recharge of water 

from agricultural areas. Water samples from nearby 

wells suggest that the elevated nitrate concentrations 

are diluted by ground water that originates as recharge 

from Oak Glen Creek. 

Ground water was found to have a range of tritium activity, indicating different times since recharge 

and possible mixing along ground-water flow paths. 

The oldest water had tritium values less than 0.3 pCi/L, 

indicating more than 50 years since recharge. Tritium 

values greater than 0.3 pCi/L indicate that at least part 

of the pumped water was recharged since 1952. Ground 

water near the hills and mountains—in particular, 

ground water that is north of the Oak Glen Fault, or east 

of the Casa Blanca Barrier and north of the South Mesa 

Barrier—had tritium values similar to those of surfacewater samples and indicates that it is likely to be the 

most recently recharged ground water. 

Flowmeter data from well 1S/2W-25R4 showed 

that more than one-half of the water flowed into the 

well between depths of 450 and 600 ft below land surface. At a flow rate of 750 gal/min, virtually no water 

was contributed to the well below a depth of about 820 

ft. Water recharged since 1952 was found in the uppermost part of the well. Water flowing into the well from 

depths below 590 ft probably was recharged more than 

50 years and less than about 400 years before present. 

Tritium and flowmeter data from well 1S/2W-25R4 

suggest that the well could extract additional water if 

perforations were present between the water table at a 

depth of about 300 ft below land surface and the top of 

existing perforations at a depth of 450 ft. 

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Burnham, W.L., and Dutcher, L.C., 1960, Geology and 

ground-water hydrology of the Redlands–Beaumont 

area, California, with special reference to ground-water 

outflow: U.S. Geological Survey Open-File Report, 

352 p. 

California Department of Water Resources, 1970, Meeting 

water demands in the Bunker Hill–San Timoteo 

area—Geology, hydrology, and operation–economics 

studies: California Department of Water Resources 

Bulletin 104-5, 75 p. 

———1979, Preliminary evaluation of State Water Project 

ground-water storage program, Bunker Hill–San 

Timoteo–Yucaipa basins: 82 p. 

———1986, San Bernardino–San Gorgonio water resources 

management investigation: Southern District, 83 p. 

Camp, Dresser, and McKee, 1994, Water facilities master 

plan for the Yucaipa Valley Water District: Final water 

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Craig, H., 1961, Isotope variation in meteoric waters: Science, v. 133, p. 1702–1703. 

Dutcher, D.L., and Burnham, W.L., 1959, Geology and 

ground-water hydrology of the Mill Creek area, San 

Bernardino County, California: U.S. Geological Survey 

Open-File Report, 229 p. 

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Ana Valley, southern California, 1927 through 1968: 

U.S. Geological Survey Open-File Report 72-0097, 

30 p. 

Eckis, Rollin, 1934, Geology and ground-water storage 

capacity of valley fill, South Coastal Basin Investigation: California Division of Water Resources Bulletin 

45, 273 p. 

Egan and Associates, Inc., 1989, Plan of water system development: Report to Western Heights Water Company 

[variously paged]. 

Fishman, M.J., 1993, Methods for analysis by the United 

States Geological Survey National Water Quality Laboratory—Determination of inorganic and organic constituents in water and fluvial sediments: U.S. 

Geological Survey Open-File Report 93-125, 217 p. 

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determination of inorganic substances in water and fluval sediments: Techniques of Water-Resources Investigations of the United States Geological Survey, book 5, 

chap. A1, 545 p. 

Fletcher, G.L., 1976, Fluctuation of water levels in wells in 

the Yucaipa area, 1965–75: San Bernardino Valley 

Municipal Water District, Report No. ENG–76–E2, 

17 p. 

Fox, R.C., 1987, A hydrogeologic analysis and projected 

water level decline in Western Heights subbasin: A 

report for Western Heights Water Company, 21 p. 

———1990, Groundwater resources monitoring plan: A 

report for Yucaipa Valley Water District, v. 1, 136 p. 

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Harris, J.M., 1992, Stable isotope composition of 

waters in southeastern California: Journal of Geophysical Research, v. 97, no. D5, p. 5795–5812. 

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p. 534–536. 

34 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
Gossell, M.A., Hanson, R.T., Izbicki, J.A., and Nishikawa, 

Tracy, 1995, Application of impeller-flow meter and 

discrete water-sampling techniques for improved 

ground-water well construction [abs.]: Eos, v. 76, 

no. 46, p. 182. 

Harden, D.R., 1998, California Geology: Upper Saddle 

River: New Jersey, Prentice-Hall, Inc., 479 p. 

Horowitz, A.J., Demas, C.R., Fitzgerald, K.K., Miller, T.L., 

and Rickert, D.A., 1994, U.S. Geological Survey protocol for the collection and processing of surface-water 

samples for the subsequent determination of inorganic 

constituents in filtered water: U.S. Geological Survey 

Open-File Report 94-539, 57 p. 

International Atomic Energy Agency, 1981, Stable isotope 

hydrology: Deuterium and oxygen-18 in the water 

cycle: Technical Reports Series No. 210, 337 p. 

Izbicki, J.A., 1996, Use of 18O and D to define seawater 

intrusion, in Bathala, C.T., ed., North America Water 

and Environment Congress, Anaheim, California, June 

23–28, Proceedings: New York, American Society of 

Civil Engineers, 1 CD-ROM. 

Izbicki, J.A., Christensen, A.H, and Hanson, R.T., 1999, U.S. 

Geological Survey combined well-bore flow and depthdependent water sampler, U.S. Geological Survey Fact 

Sheet 196-99, 2 p. 

Izbicki, J.A., Danskin, W.R, and Mendez, G.O., 1997, 

Chemistry and isotopic composition of ground water 

along a section near the Newmark area, San Bernardino 

County, California, U.S. Geological Survey WaterResources Investigations Report 97-4179, 27 p. 

Magaritz, M., Aravena, R, Pena, H., Suzuki, O., and Grilli, 

A., 1989, Water chemistry and isotopic study of streams 

and springs in northern Chile: Journal of Hydrology, 

v. 108, p. 323–341. 

Mann, J.F., Jr., 1986, Revised safe yield of the Yucaipa subbasins: San Bernardino Valley Muncipal Water District, 

unpub. report, 7 p. 

Mann, J.F., Jr., and Todd, D.K., 1990, Perennial yield, 

Yucaipa groundwater basin: San Bernardino Valley 

Muncipal Water District and Yucaipa Valley Water District, unpub. report, 4 p. 

Matti, J.C., and Carson, S.E., 1991, Liquefaction susceptibility in the San Bernardino Valley and vicinity, southern 

California—A regional evaluation: U.S. Geological 

Survey Bulletin 1898, 53 p. 

Matti, J. C., Morton, D.M., Cox, B.F., Carson, S.E., and 

Yetter, T.J., 1992, Geologic map of the Yucaipa quadrangle, San Bernardino and Riverside Counties, California: U.S. Geological Survey Open-File Report 92-

446, 14 p. and 1 map sheet. 

Mendenhall, W.C., 1905, The hydrology of San Bernardino 

Valley, California: U.S. Geological Survey WaterSupply Paper 142, 124 p. 

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oceans and their implications: Nature, v. 263, p. 

103–106. 

———1989, Tritium deposition in the continental United 

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analysis by means of patterns: Journal of Petroleum 

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1996, Methods of analysis by the United States Geological Survey National Water Quality Laboratory—Determination of dissolved aluminum and boron in water by 

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17 p. 

Todd, D.K., 1988, Perennial yield of the Yucaipa groundwater basin: Report to Yucaipa Valley Water District, 71 p. 

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water standards and health advisories table: U.S. Environmental Protection Agency, Region IX, San Francisco, California, 25 p. 

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Geological Survey Techniques of Water-Resources 

Investigations, book 9, chap. A6, 218 p. 

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California, in Marston, R.A. and Hasfuther, V.R., 

Effects of human-induced changes on hydrologic systems: American Water Resources Association, 

p. 923–932. 

Selected References 35 
Table 2. Chemical and isotopic analyses of water from selected surface-water sites in the Yucaipa area, southern California 

[USGS, U.S. Geological Survey; ft3/s, cubic foot per second; HS/cm, microsiemen per centimeter at 25 °C; mg/L, milligram per liter; °C, degree Celsius; B, 

base flow; Hg/L, micrograms per liter; pCi/L, picocurie per liter; per mil, parts per thousand; <, less than; —, no data] 

USGS station name USGS station number Date Time Discharge 

(ft3/s) 

Specific 

conductance pH, field 

(HS/cm) (standard units) 

Upper Oak Glen Creek in Ford Canyon 340326116560501 4/30/98 1715 0.31B 216 7.8 

Oak Glen Creek in Ford Canyon 340326116560601 7/31/97 0940 .60B 351 8.4 

Oak Glen Creek near Oak Glen 340307116592101 2/3/98 1645 2.2 260 8.3 

1/13/98 0750 .79B 395 8.5 

1/3/97 1040 1.4 361 8.5 

Oak Glen Creek at 2nd St. 340238117023201 2/23/98 1545 6.9 190 8.5 

2/23/98 1330 2.3 384 8.6 

2/3/98 1615 4.3 117 7.9 

Yucaipa Creek at Mesa Grande Bridge 340051117002601 2/23/98 2115 100 74 7.5 

2/19/98 2245 15 63 7.6 

Yucaipa Creek at 5th St. 340049117031401 2/23/98 2200 110 75 7.8 

2/20/98 0010 26 55 7.9 

2/3/98 1530 2.4 78 7.7 

Yucaipa Creek below Dunlap Acres 340037117064301 2/3/98 1430 190 172 8.3 

Mill Creek at Yucaipa Regional Park 340316117025101 7/10/96 1330 1.0B 240 8.1 

Oxygen, Temp- Temp- Calcium, Magnesium, Sodium, 

dissolved erature, erature, dissolved dissolved dissolved 

(mg/L) air (°C) water (°C) (mg/L) (mg/L) (mg/L) 

Upper Oak Glen Creek in Ford Canyon — 15.5 7.5 24 9.4 4.4 

Oak Glen Creek in Ford Canyon 8.5 17.0 12.5 40 15 7.6 

Oak Glen Creek near Oak Glen — 5.5 6.5 30 9.6 8.1 

10.8 6.0 7.5 45 16 15 

— 13.0 12.0 43 14 12 

Oak Glen Creek at 2nd St. — 11.0 11.0 23 7.6 6.7 

9.4 13.0 12.5 — — — 

— 6.0 7.0 13 3.8 3.8 

Yucaipa Creek at Mesa Grande Bridge — 10.0 9.0 8.3 2.1 2.4 

— 9.0 7.0 6.9 1.8 2.2 

Yucaipa Creek at 5th St. — 11.0 7.0 8.9 2.3 3.1 

— 7.0 6.5 5.8 1.5 2.2 

— 10.0 8.5 9.1 2.2 2.8 

Yucaipa Creek below Dunlap Acres 10.6 12.0 11.0 20 4.3 5.2 

Mill Creek at Yucaipa Regional Park 8.2 32.5 15.5 28 5.7 4.7 

36 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
Table 2. Chemical and isotopic analyses of water from selected surface-water sites in the Yucaipa area, southern California—Continued 

Potassium Alkalinity, Sulfate, Chloride, Fluoride, Bromide, 

dissolved field dissolved dissolved dissolved dissolved 

(mg/L) (mg/L as CaCO3) (mg/L) (mg/L) (mg/L) (mg/L) 

USGS station name 

Upper Oak Glen Creek in Ford Canyon 2 98 6.7 1.6 0.7 <0.01 

Oak Glen Creek in Ford Canyon 3 160 17 2.2 .8 <.01 

Oak Glen Creek near Oak Glen 2 99 22 4.3 .8 <.01 

2 150 32 7.7 .5 .02 

2 130 37 6.2 .5 — 

Oak Glen Creek at 2nd St. 2 — 17 3.3 .3 <.01 

— — — — — — 

2 45 7.8 2.5 .2 <.01

Yucaipa Creek at Mesa Grande Bridge .9 27 2.2 1.7 .1 <.01

.9 24 1.9 1.6 .1 <.01

Yucaipa Creek at 5th St. .9 34 2.5 1.7 .1 <.01

.7 22 1.4 1.3 .1 <.01

1 28 3.2 1.4 .2 <.01

Yucaipa Creek below Dunlap Acres 1 43 22 2.5 .3 <.01

Mill Creek at Yucaipa Regional Park 2 84 13 1.2 .8 <.01

Iodide, Silica, Residue at Nitrite, NO2 + NO3, Ammonia, 

dissolved dissolved 180°C dissolved dissolved dissolved 

(mg/L) (mg/L) (mg/L) (mg/L as N) (mg/L as N) (mg/L as N) 

Upper Oak Glen Creek in Ford Canyon <0.001 7.0 120 0.01 0.19 0.05

Oak Glen Creek in Ford Canyon <.001 10 200 <.01 .21 <.01

Oak Glen Creek near Oak Glen .001 11 162 <.01 .92 <.02

.001 21 249 <.01 2.3 .03

.001 17 227 .03 1.5 .08

Oak Glen Creek at 2nd St. .002 8.5 124 <.01 1.5 .07

— — — — — 

.001 4.3 74 <.01 .41 .04

Yucaipa Creek at Mesa Grande Bridge .001 4.4 51 <.01 .67 .06

.001 3.3 41 <.01 .53 <.02

Yucaipa Creek at 5th St. .001 5.2 55 <.01 .97 <.02

.001 3.2 40 <.01 .57 .04

.002 3.2 57 .01 1.6 .09

Yucaipa Creek below Dunlap Acres .002 3.3 108 .03 1.8 .09

Mill Creek at Yucaipa Regional Park <.001 12 137 <.01 .18 .02

Table 2 37 
H H H

H H H

Table 2. Chemical and isotopic analyses of water from selected surface-water sites in the Yucaipa area, southern California—Continued 

Ammonia + Phosphorus, Phosphorus Arsenic, Barium, Boron, Iron, ortho, organic, dissolved dissolved USGS station name dissolved dissolved dissolved dissolved

(mg/L as N) (mg/L as P) (mg/L as P) (Hg/L) (Hg/L) (Hg/L) (Hg/L) 

Upper Oak Glen Creek in Ford Canyon <0.10 <0.01 0.02 <1 5.3 <16 <10 

Oak Glen Creek in Ford Canyon <.20 <.01 <.01 <1 20 7 <3 

Oak Glen Creek near Oak Glen .20 .03 .05 <1 12 22 21 

.13 .04 .03 <1 18 <16 <10 

<.20 .02 .02 <1 19 20 14 

Oak Glen Creek at 2nd St. .30 .04 .05 <1 7.0 22 <10 

— — — — — — — 

.37 .05 .05 <1 7.0 19 100 

Yucaipa Creek at Mesa Grande Bridge .46 .21 .19 <1 7.0 20 34 

.46 .20 .20 <1 6.0 <16 48 

Yucaipa Creek at 5th St. .43 .21 .20 <1 5.7 18 25 

.35 .22 .22 <1 4.3 19 110 

.61 .23 .27 <1 6.0 23 52 

Yucaipa Creek below Dunlap Acres .67 .19 .20 <1 8.0 24 29 

Mill Creek at Yucaipa Regional Park <.20 <.01 .01 <1 10 9 <3 

Lithium, Manganese, Strontium, H-2/H-1 O-18/O-16 Tritium, 

dissolved dissolved dissolved isotope ratio isotope ratio total 

(Hg/L) (Hg/L) (Hg/L) (per mil) (per mil) (pCi/L) 

Upper Oak Glen Creek in Ford Canyon <4 9 80 −63.3 −9.87 14 

Oak Glen Creek in Ford Canyon <4 <1 190 −70.7 −10.48 7.3 

Oak Glen Creek near Oak Glen <4 15 120 −92.4 −12.73 — 

<4 9 180 −63.5 −9.59 — 

<4 3 190 −59.7 −8.85 9.2 

Oak Glen Creek at 2nd St. <4 8 110 −32.8 −5.58 — 

— — — — — — 

<4 5 60 −99.9 −13.61 — 

Yucaipa Creek at Mesa Grande Bridge <4 4 50 −38.9 −6.95 — 

<4 6 50 −77.9 −11.74 — 

Yucaipa Creek at 5th St. <4 <4 50 −42.8 −7.01 — 

<4 8 40 −76.6 −11.60 — 

<4 6 60 −99.0 −13.14 — 

Yucaipa Creek below Dunlap Acres <4 4 100 −75.8 −11.23 — 

Mill Creek at Yucaipa Regional Park 5 1 70 −78.6 −11.30 18 

38 Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 
Table 3. Chemical and isotopic analyses of water from selected wells in the Yucaipa area, southern California 

[State well number, see “Well-Numbering System” in text; USGS, U.S. Geological Survey; gal/min, gallons per minute; ft blw LSD, feet below land-surface datum; H

°C; mg/L, milligram per liter; Hg/L, microgram per liter; pCi/L, picocurie per liter; per mil, parts per thousand; °C, degree Celsius; B, bulk sample; <, less than; —, n

State well number USGS station number Date Time Flow rate (gal/min) Depth to sample (ft blw LSD) Specific conductance (HS/cm) pH, field (standard units) Oxyg

disso

(mg

1S/1W-19G01 340415117012701 7/29/97 1330 180 — 745 7.3 61S/1W-27L01 340312116583901 7/29/97 0930 240 — 568 7.1 41S/1W-32C01 340253117002701 7/29/97 1145 90 — 476 7.2 61S/2W-24C02 340438117024201 7/31/97 1230 — — 650 7.4 61S/2W-25A01 340343117021201 7/17/97 1330 260 — 584 7.6 81S/2W-25R04(B) 340255117021601 2/25/98 1600 750 — 477 7.6 — 

-25R04 340255117021601 2/25/98 1730 750 480 458 7.4 8-25R04 340255117021601 2/25/98 1930 750 590 491 7.4 7-25R04 340255117021601 2/25/98 2100 750 770 510 7.5 7-25R04 340255117021601 2/25/98 2330 750 820 513 7.5 6-25R04 340255117021601 2/26/98 0030 750 900 486 7.4 6-25R04(B) 340255117021601 5/1/98 1000 1450 — 463 7.6 8

1S/2W-34N01 340202117050201 7/10/96 1430 600 — 831 7.6 51S/2W-36G01 340236117023101 7/18/97 0950 1,700 — 466 7.6 62S/1W-08F01 340054117002901 7/16/97 1210 250 — 601 7.2 52S/1W-15F02 340003116582501 7/16/97 1430 140 — 445 7.8 2S/2W-01J011 340124117021301 6/2/98 1945 2.5 — 1,100 7.8 2S/2W-02M01 340129117035101 7/15/97 1200 550 — 569 7.7 8

-02M01 340129117035101 7/10/98 1210 550 — 553 7.7 — 

2S/2W-03E01 340148117045401 7/9/96 1330 1,200 — 734 7.5 62S/2W-03L01 340129117044201 7/11/96 1120 450 — 498 7.7 92S/2W-04G03 340144117053601 7/10/96 1020 1,000 — 477 7.6 42S/2W-04G04 340137117053501 4/30/98 1430 1,550 — 417 7.6 32S/2W-04J02 340135117051601 7/10/96 0900 2,000 — 455 7.7 52S/2W-04R01 340120117051301 7/9/96 1430 300 — 717 7.4 12S/2W-10B02 340106117045001 7/11/96 0930 750 — 510 7.8 72S/2W-11A01 340105117031601 7/15/97 1450 725 — 496 7.8 62S/2W-11D01 340057117040601 7/15/97 1000 700 — 462 7.8 82S/2W-14C01 340014117034301 7/17/97 1000 250 — 522 7.6 82S/2W-14R03 335924117031701 7/17/97 0915 775 — 297 9.3 12S/2W-24L01 335848117024301 7/16/97 0925 2,100 — 346 7.9 52S/2W-28C021 335829117055201 7/28/97 1620 — — 942 7.6 

Table 3 3

See footnote at end of table. 

9 
40 Table 3. Chemical and isotopic analyses of water from selected wells in the Yucaipa area, southern California—Continued 

Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 Calcium, Magnesium, Sodium, Potassium, Alkalinity, Sulfate, Chloride, Fluoride, 

State well number dissolved dissolved dissolved dissolved field dissolved dissolved dissolved 

(mg/L) (mg/L) (mg/L) (mg/L) (mg/L as CaCO3) (mg/L) (mg/L) (mg/L) 

1S/1W-19G01 78 18 42 1 190 86 34 0.8 1S/1W-27L01 67 22 14 2 220 69 9.7 .7 1S/1W-32C01 53 16 16 2 170 39 11 .5 1S/2W-24C02 69 15 42 1 220 57 18 .8 1S/2W-25A01 57 11 45 1 200 31 30 .8 1S/2W-25R04(B) 59 12 25 2 190 28 6.9 .6 

-25R04 55 12 23 2 200 27 6.4 .6 -25R04 61 13 25 2 180 29 7.3 .6 -25R04 63 13 28 2 190 29 7.9 .6 -25R04 63 13 23 2 140 29 8.0 .6 -25R04 61 14 21 2 170 27 7.0 .6 -25R04(B) 61 12 24 2 — 24 6.3 .6 

1S/2W-34N01 95 23 40 2 210 60 32 .5 1S/2W-36G01 53 12 24 2 190 32 7.3 .5 2S/1W-08F01 62 19 33 .6 230 29 28 .6 2S/1W-15F02 34 20 25 5 190 16 18 .4 2S/2W-01J011 34 1.0 200 1 170 260 36 6.0 2S/2W-02M01 68 12 28 2 200 31 19 .7 

-02M01 70 13 25 3 190 29 17 .5 

2S/2W-03E01 98 22 21 2 220 68 17 .5 2S/2W-03L01 63 13 21 2 160 30 17 .5 2S/2W-04G03 58 12 22 2 180 31 12 .6 2S/2W-04G04 50 8.5 27 2 160 27 7.9 .6 2S/2W-04J02 61 12 17 2 170 29 7.8 .5 2S/2W-04R01 94 22 23 2 240 74 15 .5 2S/2W-10B02 55 8.7 41 3 160 — — — 2S/2W-11A01 46 8.0 44 2 160 39 18 .9 2S/2W-11D01 46 6.8 39 2 160 36 16 .6 2S/2W-14C01 51 14 33 1 200 13 26 .9 2S/2W-14R03 5.8 .9 58 .6 100 15 14 .5 2S/2W-24L01 28 3.5 39 2 140 14 11 .5 2S/2W-28C021 59 17 120 1 380 32 65 1.0 See footnote at end of table. 
A

H 

Table 3. Chemical and isotopic analyses of water from selected wells in the Yucaipa area, southern California—Continued 

State well number 

Silica, 

dissolved 

(mg/L) 

Residue at 

180AC 

(mg/L) 

Nitrite, 

dissolved 

(mg/L as N) 

NO2 + NO3, 

dissolved 

(mg/L as N) 

Ammonia, 

dissolved 

(mg/L as N) 

Ammonia + 

organic, 

(mg/L as N 

Phosphorus, 

dissolved 

(mg/L as P) 

Phosphorus 

ortho, 

dissolved 

(mg/L as P) 

Ars

dis

(H

1S/1W-19G01 23 485 0.09 13 0.14 0.2 <0.01 0.02 <1S/1W-27L01 20 358 <.01 2.0 .03 <.2 <.01 <.01 <1S/1W-32C01 21 298 .02 5.3 .02 <.2 <.01 .01 <1S/2W-24C02 25 412 <.01 5.6 <.02 <.2 <.01 .02 <1S/2W-25A01 25 359 <.01 4.7 <.02 <.2 .01 .02 <1S/2W-25R04(B) 28 295 <.01 2.0 .03 <.1 <.01 .02 

-25R04 28 283 <.01 1.9 .03 <.1 <.01 .02 -25R04 28 305 <.01 2.2 .03 <.1 <.01 .02 -25R04 28 317 <.01 1.9 .02 <.1 <.01 .02 -25R04 28 315 <.01 1.4 .03 <.1 <.01 .02 -25R04 28 303 <.01 1.0 .03 <.1 <.01 .02 -25R04(B) 26 290 .01 2.0 .06 <.1 <.01 <.01 

1S/2W-34N01 25 512 <.01 24 .02 <.2 .01 .03 <1S/2W-36G01 26 293 <.01 2.1 <.02 <.2 <.01 .01 <2S/1W-08F01 24 369 <.01 4.2 <.02 <.2 .03 .03 <2S/1W-15F02 17 258 <.01 .06 <.02 <.2 <.01 <.01 <2S/2W-01J011 16 712 .05 5.3 .08 <.1 <.01 .02 <2S/2W-02M01 23 363 <.01 7.9 <.02 <.2 <.01 .01 <

-02M01 25 354 <.01 7.8 .03 <.1 <.01 .02 <

2S/2W-03E01 24 487 <.01 16 .03 <.2 <.01 .02 <2S/2W-03L01 26 314 <.01 6.7 .03 .2 <.01 .02 <2S/2W-04G03 24 287 <.01 1.6 .03 <.2 .03 .02 <2S/2W-04G04 23 260 .01 1.3 .05 <.1 <.01 .02 <2S/2W-04J02 25 281 <.01 2.6 .03 <.2 <.01 .02 <2S/2W-04R01 25 472 .01 9.6 .03 <.2 .02 .03 <2S/2W-10B02 — — <.01 4.9 .02 <.2 <.01 .01 <2S/2W-11A01 24 318 <.01 5.8 <.02 <.2 .02 .02 <2S/2W-11D01 22 294 <.01 3.9 <.02 <.2 .03 .02 <2S/2W-14C01 26 318 <.01 4.2 <.02 <.2 .03 .03 <2S/2W-14R03 15 186 <.01 1.9 <.02 <.2 <.01 .02 2S/2W-24L01 17 213 <.01 2.0 <.02 <.2 <.01 .01 <2S/2W-28C021 22 563 .02 <.05 .44 .3 .01 .13 <

Table 3 See footnote at end of table. 41 
H H H H

42 Table 3. Chemical and isotopic analyses of water from selected wells in the Yucaipa area, southern California—Continued 

Iron, Lithium, Manganese, Strontium, H-2/H-1 O-18/O-16 Tritium, 

State well number dissolved dissolved dissolved dissolved isotope ratio isotope ratio total 

(Hg/L) (Hg/L) (Hg/L) (Hg/L) (per mil) (per mil) (pCi/L) 

1S/1W-19G01 140 5 67 490 −56.5 −8.45 7.3 1S/1W-27L01 <3 4 <1 270 −65.5 −9.69 9.6 1S/1W-32C01 31 <4 6 250 −61.9 −9.24 11 1S/2W-24C02 <3 4 <1 350 −56.1 −8.55 2.8 1S/2W-25A01 9 <4 <1 340 −55.6 −8.19 2.8 1S/2W-25R04(B) <10 <4 <4 250 −60.1 −8.99 2.1 

-25R04 <10 <4 <4 230 −63.2 −9.23 3.9 

-25R04 70 <4 <4 260 −58.1 −8.85 <.3 -25R04 <10 <4 <4 270 −58.8 −8.76 .4 -25R04 34 <4 <4 270 −58.8 −8.68 .8 -25R04 <10 <4 <4 260 −58.4 −8.86 1.4 -25R04(B) 19 <4 <4 251 −61.0 −9.07 3.4 

1S/2W-34N01 12 <4 2 470 — — 2.4 1S/2W-36G01 <3 <4 <1 230 −60.2 −9.02 2.9 2S/1W-08F01 <3 <4 <1 270 −56.6 −8.46 7.7 2S/1W-15F02 39 <4 5 170 −53.8 −8.11 .6 2S/2W-01J011 2,300 <4 23 362 −67.3 −9.97 7.2 2S/2W-02M01 4 <4 <1 290 — — 4.6 

-02M01 17 <4 <4 296 −57.8 −8.59 — 

2S/2W-03E01 8 <4 <1 390 −55.2 −8.41 15 2S/2W-03L01 <3 <4 <1 270 −58.4 −8.65 2.8 2S/2W-04G03 4 <4 <1 260 −57.0 −8.50 <.3 2S/2W-04G04 <10 <4 <4 254 −58.4 −8.63 <.3 2S/2W-04J02 <3 <4 <1 250 −58.0 −8.82 <.3 2S/2W-04R01 22 <4 <1 350 −58.4 −8.64 1.8 2S/2W-10B02 <3 <4 <1 270 −57.8 −8.56 1.9 2S/2W-11A01 <3 <4 <1 260 −58.6 −8.52 2.1 2S/2W-11D01 6 <4 <1 260 −58.7 −8.54 1.2 2S/2W-14C01 <3 <4 <1 230 −55.3 −8.11 .8 2S/2W-14R03 <3 <4 <1 50 −57.5 −8.60 .7 2S/2W-24L01 3 <4 <1 330 −59.9 −8.81 .7 2S/2W-28C021 95 4 410 520 −47.3 −6.35 7.8 

Surface-Water and Ground-Water Quality in the Yucaipa Area, San Bernardino and Riverside Counties, California, 1996–98 

1Not a production well.