Virus Fate and Transport During Recharge 

Using Recycled Water at a Research Field 

Site in the Montebello Forebay, Los 

Angeles County, California, 1997–2000

By Robert Anders, William A. Yanko, Roy A. Schroeder, and James L. Jackson

In cooperation with the

Water Replenishment District of Southern California and the

County Sanitation Districts of Los Angeles County

Scientific Investigations Report 2004-5161

U.S. Department of the Interior

U.S. Geological Survey
U.S. Geological Survey, Reston, Virginia: 2004

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225-0286

U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS

World Wide Web: http://www.usgs.gov/

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Anders, R., Yanko, W.A., Schroeder, R.A., and Jackson, J.L., 2004, Virus fate and transport during recharge using recycled water at a research field site in the Montebello Forebay, Los Angeles County, California, 1997-–2000: U.S. Geological Survey Scientific Investigations Report 2004–5161, 65 p.
iii

Contents

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

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

Artificial Recharge Using Wastewater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Prior Recharge Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Description of Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Research Field Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Site Characterization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Microbiological Changes During Recharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Methods and Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Field Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Bromide Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Bacteriophage Assays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Model Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Virus Fate and Transport During Recharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Water Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Results from Tracer Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

First Tracer Experiment, August 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Second Tracer Experiment, August–September 1998 . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Third Tracer Experiment, August 2000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Inactivation Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Attenuation Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Collision Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

References Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Appendixes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
iv

Figures

Figure 1. Map showing location of the research field site in the Montebello Forebay, 

Los Angeles County, California. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Figure 2. Schematic cross section showing research field site with the

PVC monitoring wells (PR8–PR11; PR14 and PR15, located 45.7 m 

north of the test basin, in the upgradient direction of ground-water

flow, not shown), steel well points (WP1–WP8), and stainlesssteel implants (GP1–GP5). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Figure 3. Graph showing grain-size distribution for core material from selected 

depths beneath the research field site, Los Angeles County, California. . . . . . . . . . 7

Figure 4. Graph showing bacteriophage PRD1 concentrations in water samples 

collected from the test basin and WP1 and bromide concentrations

in water samples collected from WP1 during the first tracer experiment, 

August 1997, from a research field site located in 

Los Angeles County, California. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 5. Graph showing bromide concentrations during the second tracer 

experiment, August–September, 1998, from a research field site 

located in Los Angeles County, California.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 6. Graph showing bacteriophage MS2 concentrations during the second 

tracer experiment, August–September 1998, from a research field 

site located in Los Angeles County, California. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 7. Graph showing bacteriophage PRD1 concentrations during the 

second tracer experiment, August–September 1998, from a 

research field site located in Los Angeles County, California. . . . . . . . . . . . . . . . . . . 17

Figure 8. Graph showing bromide concentrations during the third tracer experiment, 

August 2000, from a research field site located in Los Angeles County,

California. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 9. Graph showing bacteriophage MS2 concentrations during the third 

tracer experiment, August 2000, from a research field site located

in Los Angeles County, California. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figure 10. Graph showing bacteriophage PRD1 concentrations during the third

tracer experiment, August 2000, from a research field site located

in Los Angeles County, California. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Figure 11. Graph showing normalized log-concentrations of MS2 and PRD1 in the

test basin as a function of time for the second tracer 

experiment, August–September 1998. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 12. Graph showing normalized log-concentrations of MS2 and PRD1 in the

test basin as a function of time for the third tracer experiment,

August 2000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure 13. Graphs showing bacteriophage to bromide ratio plots for the test 

basin and selected depths beneath the test basin

at 3, 6, 9, and 21 hours after the addition ofbacteriophage and 

bromide during the second tracer experiment,

August–September 1998, from a research field site located in

Los Angeles County, California. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Figure 14. Graphs showing attenuation rates, defined as the logarithmic 

reduction in the bacteriophage to bromide ratio, for MS2

and PRD1 during the second tracer experiment, 

August–September 1998, from a research field site 

located in Los Angeles County, California.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Figure 15. Graphs showing attenuation rates, defined as the logarithmic reduction

in the bacteriophage to bromide ratio, for MS2 and PRD1 during 

he third tracer experiment, August 2000, from a research field site

located in Los Angeles County, California.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
vi

Tables

Table 1. Distribution of selected bacteria in core samples collected during 

construction of the research field site, Los Angeles County, California . . . . . . . . . . 8

Table 2. Distribution of selected bacteria in water samples collected during the 

second recharge experiment: immediately before recharge, 

2 days after recharge began, and more than 1 month after recharge

was discontinued . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Table 3. Parameter values used to calculate collision efficiencies for MS2 and 

PRD1 during the second and third tracer experiments in 

Los Angeles County, California. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Appendixes

Appendix A. Water-quality data for selected wells at the research field site in 

Montebello Forebay, Los Angeles County, California, 1997–2000 . . . . . . . . . . . . . . . 32

Appendix B. Measured bacteriophage concentrations for water samples collected

during the 1997 tracer experiment from a research field site located 

in Los Angeles County, California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Appendix C. Measured bromide concentrations for water samples collected during

the 1998 tracer experiment from a research field site located in

Los Angeles County, California. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Appendix D. Measured bacteriophage concentrations for water samples collected 

during the 1998 tracer experiment from a research field site located 

in Los Angeles County, California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Appendix E. Measured bromide concentrations for water samples collected during

the 2000 tracer experiment from a research field site located in 

Los Angeles County, California. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Appendix F. Measured bacteriophage concentrations for water samples collected 

during the 2000 tracer experiment from a research field site located

in Los Angeles County, California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
vii

CONVERSION FACTORS, VERTICAL DATUM, AND 

ABBREVIATIONS

CONVERSION FACTORS 

Temperature in degrees Celsius (oC) may be converted to degrees Fahrenheit (oF) as follows:

oF=1.8 oC+32.

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 

25oC).

Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) or 

micrograms per liter (μg/L). 

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. 

ABBREVIATIONS

Constituents or properties

α collision efficiency, defined in equation 2

αL longitudinal dispersivity

As Happel sphere-in-cell model correction factor, defined in equation 4 

Br0 initial bromide concentration

Br(t) time-dependent bromide concentration

C0 initial bacteriophage concentration

C(t) time-dependent bacteriophage concentration

Multiply By To obtain

Length

millimeter (mm) 0.03937 inch

meter (m) 3.281 foot 

kilometer (km) 0.6214 mile 

Area

hectare (ha) 2.471 acre

square meter (m2) 10.76 square foot 

square centimeter (cm2) 0.1550 square inch 

Volume

cubic centimeter (cm3) 0.06102 cubic inch 

cubic meter (m3) 0.0008107 acre-foot 

Flow rate

cubic meter per year (m3/yr) 0.000811 acre-foot per year 

meter per day (m/d) 3.281 foot per day

liter per second (L/s) 15.85 gallon per minute 

Mass

kilogram (kg) 2.205 pound avoirdupois

Pressure

kilopascal (kPa) 0.1450 pound per square inch 
viii

CaCl2 calcium chloride

dp average grain diameter of the porous particle

dv diameter of virus 

D hydrodynamic dispersion coefficient

De effective diffusion coefficient

ε equal to (1-θ)

1/3

η single collector efficiency, defined in equation 3

GP stainless steel implants 

kB Boltzman’s constant

λ inactivation rate coefficient of bacteriophage 

lz distance between injection and sampling locations

μ viscosity of the liquid

MgCl magnesium chloride

PR PVC monitoring wells

PVC polyvinyl chloride

q specific discharge

θ porosity of the porous medium

r

2 coefficient of determination

t time

t0 beginning times

tf ending times

TSA trypticase soy agar

TSB trypticase soy broth

T solute temperature

U average interstitial velocity

WP steel well points

Other abbreviations 

oC degrees Celsius

cfu colony-forming units

cfu/gm colony-forming units per gram

cfu/mL colony-forming units per millilter

gm gram

> greater than

< less than

L liter

m meter
ix

μL microliter

μg/L micrograms per liter 

μS/cm microsiemens per centimeter at 25 oC

mg/L milligrams per liter

mL milliliter

mM millimole

MPN most probable number

MPN/mL most probable number per milliliter

PFU plaque-forming units

PFU/mL plaque-forming units per milliliter

pH log hydrogen concentration

RB relative breakthrough, defined in equation 1

Organizations 

ATCC American Type Culture Collection

CSDLAC County Sanitation Districts of Los Angeles County

NWQL U.S. Geological Survey National Water Quality Laboratory

USGS U. S. Geological Survey 
x

WELL-NUMBERING SYSTEM

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

system for the subdivision of public lands. Identification consists of the township 

number, north or south; the range number, east or west; and the section number. Each 

section is 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 002S011W018L001S. In this report, well numbers are abbreviated 

and written 2S/11W-18L1. Wells in the same township and range are referred to only by 

their section designation, -18L1. The following diagram shows how the number for 

well 2S/11W-18L1 is derived.

2S/11W-18L1

D C B A

E F G H

M L K J

N P Q R

6 5 4 3 2 1

7 8 9 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

R11W R10W

T3S

T2S

T1S

R12W

RANGE

TOWNSHIP

R14W R13W

T4S

T5S

Approximately

6 miles

Approximately

1 mile

Approximately

1/4 mile

R11W

Well-numbering diagram

SECTION 18

T2S
Virus Fate and Transport During Recharge Using Recycled 

Water at a Research Field Site in the Montebello Forebay, 

Los Angeles County, California, 1997–2000

By Robert Anders, William A. Yanko, Roy A. Schroeder, and James L. Jackson

Abstract

Total and fecal coliform bacteria distributions in 

subsurface water samples collected at a research field site in 

Los Angeles County were found to increase from 

nondetectable levels immediately before artificial recharge 

using tertiary-treated municipal wastewater (recycled water). 

The rapid increase indicates that bacteria can move through the 

soil with the percolating recycled water over intervals of a few 

days and vertical and horizontal distances of about 3 meters. 

This conclusion formed the basis for three field-scale 

experiments using bacterial viruses (bacteriophage) MS2 and 

PRD1 as surrogates for human enteric viruses and bromide as 

a conservative tracer to determine the fate and transport of 

viruses in recycled water during subsurface transport under 

actual recharge conditions. The research field site consists of a 

test basin constructed adjacent to a large recharge facility 

(spreading grounds) located in the Montebello Forebay of Los 

Angeles County, California. The soil beneath the test basin is 

predominantly medium to coarse, moderately sorted, grayishbrown sand. 

The three tracer experiments were conducted during 

August 1997, August–September 1998, and August 2000. For 

each experiment, prepared solutions of bacteriophage and 

bromide were sprayed on the surface of the water in the test 

basin and injected, using peristaltic pumps, directly into the 

feed pipe delivering the recycled water to the test basin. 

Extensive data were obtained for water samples collected from 

the test basin itself and from depths of 0.3, 0.6, 1.0, 1.5, 3.0, and 

7.6 meters below the bottom of the test basin. 

The rate of bacteriophage inactivation in the recycled 

water, independent of any processes occurring in the 

subsurface, was determined from measurements on water 

samples from the test basin. Regression analysis of the ratios of 

bacteriophage to bromide was used to determine the 

attenuation rates for MS2 and PRD1, defined as the logarithmic 

reduction in the ratio during each experiment. Although the 

inactivation rates increased during the third tracer experiment, 

they were nearly two orders of magnitude less than the 

attenuation rates. Therefore, adsorption, not inactivation, is the 

predominant removal mechanism for viruses during artificial 

recharge.

Using the colloid-filtration model, the collision efficiency 

was determined for both bacteriophage during the second and 

third field-scale tracer experiments. The collision efficiency 

confirms that more favorable attachment conditions existed for 

PRD1, especially during the third tracer experiment. The 

different collision efficiencies between the second and third 

tracer experiments possibly were due to changing hydraulic 

conditions at the research field site during each experiment. 

The field data suggest that an optimal management scenario 

might exist to maximize the amount of recycled water that can 

be applied to the spreading grounds while still maintaining 

favorable attachment conditions for virus removal and thereby 

ensuring protection of the ground-water supply.

Introduction

Artificial Recharge Using Wastewater

The use of treated municipal wastewater effluent 

(recycled water) for artificial recharge of ground water is 

increasing, especially in the southwestern United States. In Los 

Angles County, for example, approximately 60 km3 of recycled 

water is delivered annually to the Montebello Forebay in the 

northern part of the Central Ground-Water Basin. The recycled 

water, along with imported water and local runoff, is applied to 

two large spreading grounds and a portion of an unlined 

downstream river channel that have a total area of recharge of 

almost 3.5 km2. The recharged water moves down and laterally 

from the area of the spreading grounds southwest in the 

direction of regional ground-water flow (Reichard and others, 

2003). Aquifer material beneath the spreading grounds consists 

of alluvial deposits of nearly all sands and gravels, with some 

relatively fine-grained materials of possibly limited extent 

(Bookman-Edmonston Engineering Inc., 1994). 
2 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

During the practice of artificial recharge using recycled 

water, the soil is considered the final step in a multi-barrier 

treatment system to protect public health (National Research 

Council, 1994). In California, the Department of Health 

Services governs the recharge of ground water with recycled 

water. Currently, draft regulations state that the applied 

recycled water used for a surface-spreading project shall be 

retained underground for a minimum of 6 months prior to 

extraction for use as a drinking water supply, and shall not be 

extracted within 500 feet (152 m) of the point of recharge 

(Hultquist and others, 1991; Asano and Cotruvo, 2004). These 

provisions are intended to protect ground-water resources by 

ensuring that adequate soil retention time requirements are met 

for pathogen removal. 

Background

The major processes controlling the ability of viruses to 

travel long distances through the subsurface are their 

adsorption characteristics and their degree of inactivation 

(Gerba and Keswick, 1981). Inactivation of liquid-phase as 

well as sorbed or attached viruses is due to degradation of the 

viral capsid, and the most important factor controlling the 

degree of virus inactivation in the subsurface is temperature 

(Yates, 1987). The degree of virus attachment during 

subsurface transport is affected by several factors including 

viral surface properties, ground-water chemistry, and 

sediment-surface electrical charge (Gerba, 1984). Several 

investigators have described the physical and chemical factors 

that influence the adsorption process of viruses to a surface by 

the colloid-filtration model (Kinoshita and others, 1993; 

Penrod and others, 1996; Redman and others, 1997). The 

colloid-filtration model is commonly used to describe the 

removal of colloidal particles (such as viruses) during packbed filtration in water-treatment applications. The colloidfiltration model assumes that particle attachment is governed 

by their collision efficiency, which represents the ratio of the 

rate of collisions resulting in attachments to the total number 

of attachments (Yao and others, 1971; Rajagopalan and Tien, 

1976). Several laboratory- or field-scale experiments have 

been conducted to investigate the magnitude of adsorption and 

inactivation of viruses under saturated conditions (Bales and 

others, 1997; Jin and others, 1997; Pieper and others, 1997; 

Deborde and others, 1999; Ryan and others, 1999; Schijven 

and others, 1999). The magnitude of adsorption of viruses also 

was investigated by fitting experimental breakthrough curves 

to different one-dimensional advection-dispersion models (Jin 

and others, 1997; Bales and others, 1997). Finally, analytical 

solutions also were developed for virus transport in one- and 

three-dimensional, saturated, homogeneous porous media, 

accounting for virus sorption and inactivation (Sim and 

Chrysikopoulos, 1996, 1998). 

Although these approaches can provide partial 

understanding of virus transport in the subsurface, they have 

some important limitations (Yates, 1995). These limitations 

are due, in large part, to the high degree of uncertainty 

associated with site-specific information on the virus 

inactivation rate and adsorption to soil. This is because many 

of the factors controlling virus transport and inactivation are 

interrelated. Furthermore, during artificial recharge the 

subsurface beneath the spreading grounds can exhibit 

significant changes in water flux and hydraulic conductivities 

over time due to the presence of entrapped air, sealing of the 

soil surface, and the effect of biofilms sealing the pores within 

the wetted zones (Faybishenko, 1999)—conditions difficult to 

replicate in controlled laboratory experiments or to simulate in 

mathematical models. Therefore, field-scale experiments 

using surrogates for human viruses also are needed to more 

accurately determine the influence of distance and time on 

virus attenuation during subsurface transport under actual 

recharge conditions. Conducting such experiments may 

provide regulatory agencies with the information necessary to 

determine allowable limits on amounts of recycled water that 

can be used for replenishment purposes (artificial recharge) 

while ensuring that necessary retention times for pathogen 

removal are being met. 

Prior Recharge Experiments

Three previous recharge experiments were conducted at 

the research field site to better understand the microbiological 

and chemical processes that contribute to the changes in the 

quality of the recycled water during artificial recharge 

occurring over intervals of several days and vertical and 

horizontal distances of about 10 m. The first experiment was 

conducted in August 1993; the second from April–June 1994; 

and the third in July 1995. Although the primary focus of 

analyses during the recharge experiments was on a broad suite 

of inorganic, isotopic, and organic constituents, some analyses 

also were done for microorganisms. These recharge 

experiments showed: (1) reduction of nitrogen was slightly 

greater than one-third, although actual removal rates can vary 

under different environmental and operational conditions; (2) 

reduction of organic carbon was about one-third regardless of 

pre-existing conditions at the research field site; and (3) the 

total and fecal coliform bacteria distributions in subsurface 

water samples from beneath the research field site increased 

from nondetectable levels immediately before recharge with 

recycled water. Complete results of the inorganic, isotopic, 

organic, and microbiological analyses from the three recharge 

experiments are presented in other reports (Anders, 1997; 

Anders and Schroeder, 1997; Barber and others, 1997; 

Schroeder and others, 1997; Leenheer and others, 2001; 

Schroeder and others, 2003; Anders and Schroeder, 2003). 
Description of Study Area 3

Purpose and Scope

Evidence that bacteria can move through the soil along 

with the percolating recycled water during artificial recharge 

occurring over intervals of a few days and vertical and 

horizontal distances of about 3 m formed the basis for three 

tracer experiments. The tracer experiments were conducted to 

determine the fate and transport of viruses released into the 

environment during artificial recharge using recycled water. 

The purpose of this report is to present the results of these 

experiments.

The three field-scale tracer experiments were conducted 

during August 1997, August–September 1998, and August 

2000. The specific goal of the first experiment was to establish 

the feasibility of conducting field-scale tracer experiments 

under actual artificial recharge conditions using recycled water 

seeded (augmented) with high concentrations of bacteriophage 

and bromide as tracers. On the basis of the results of the first 

tracer experiment, a second tracer experiment was designed to 

measure more precisely the fate and transport of surrogates for 

human viruses under actual recharge conditions. The third 

tracer experiment was done during the summer of 2000 to 

confirm the results obtained from the second tracer experiment. 

Acknowledgments

Funds for this investigation were provided by the County 

Sanitation Districts of Los Angeles County (CSDLAC) and the 

Water Replenishment District of Southern California as part of 

the Soil Aquifer Treatment for Sustainable Water Reuse 

research program. The authors are grateful to the CSDLAC and 

U.S. Geological Survey (USGS) personnel for their assistance 

in conducting the experiments. 

Description of Study Area

Research Field Site 

The three tracer experiments were conducted at a research 

field site located at the north end of the San Gabriel River 

Coastal Basin Spreading Grounds in the Montebello Forebay, 

Los Angeles County (fig. 1). Tertiary-treated effluent from the 

San Jose Creek Water Reclamation Plant, which has undergone 

chlorination-dechlorination and either mono- (anthracite only) 

or dual-media (anthracite and sand) filtration, is delivered 

through a 2.4-m-diameter culvert to the spreading grounds. 

A portion of the flow can be diverted on demand to the research 

site through a 15.2-cm pipeline using a 1,100-m3/d pump 

installed in the culvert. During construction of the research 

field site, overlying fine-grained soil was excavated from the 

desilting basin to expose a well-sorted sand and gravel unit 

about 3 m below the local land surface. The excavated silty soil 

was used to construct a berm around the test basin to isolate it 

from the desilting basin in the adjacent large spreading 

grounds. Construction exposed an effective percolation area of 

about 500 m2 at a maximum operating water depth of about 

2.4 m.

Instrumentation at the research field site includes two 

5-cm-diameter PVC monitoring wells in the center of the test 

basin, two 5-cm-diameter PVC monitoring wells in the 

surrounding berm, and two 5-cm-diameter PVC monitoring 

wells outside the perimeter of the test basin (fig. 2). The 

monitoring wells within the test basin were installed at 15.2 m 

(PR8) and 7.6 m (PR9) below the floor of the test basin. The 

monitoring wells at the top of the 3-m berm separating the test 

basin from the desilting basin were installed at 18.3 m (PR10) 

and 10.7 m (PR11) below land surface. Two monitoring wells 

were installed 45.7 m to the north, upgradient from the test 

basin on the basis of the direction of regional ground-water 

flow, at 18.3 m (PR14) and 10.6 m (PR15) below land surface. 

All the monitoring wells at the research field site are screened 

upwards from the bottom for an interval of 1.5 m. 

In addition to the six monitoring wells, numerous steel 

well points were installed as needed (fig. 2). The well points 

consist of a conical drive shoe at the bottom (0.15 m), 0.6-m 

screens, and galvanized-steel pipe extending from the depth of 

installation to a height sufficient to provide access during 

recharge experiments. Two well points located within the 

center of the test basin were installed at depths of about 2.1 and 

3.6 m (WP1 and WP2, respectively); three well points located 

15.2 m south of the test basin, in the downgradient direction of 

regional ground-water flow, were installed at depths of about 

2.1, 3.6, and 5.7 m below land surface (WP8, WP7, and WP6, 

respectively); and three more well points located 45.7 m south 

of the test basin, in the downgradient direction of regional 

ground-water flow, were installed at depths of about 2.1, 3.5, 

and 6.3 m below land surface (WP3, WP4, and WP5, 

respectively). The six PVC monitoring wells and eight steel 

well points were hydraulically developed by air-surging. 

Other instruments installed at the research field site to 

collect water samples during the tracer experiments consist of 

15.2-cm stainless steel implants (GP1–GP5)(Geoprobe 

Systems, Salina, Kansas). These instruments were installed at 

about 0.3-m intervals to a depth of 1.5 m below the floor of the 

test basin (GP1 through GP5, respectively; fig. 2).

Schroeder and others (2003) provide additional details of 

the instrumentation at the research field site.
4 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

Los Angeles

CALIFORNIA

San

Francisco

San Diego

Los Angeles

County

Study

area

23 24 19 21 20 23

28 27 26 29 28 27

33 34 35 36 31 32 34 35

4 3 4 2

9 7

8 11 10 9 10

16 15 14 18 16 15

22 21 23 24 19 20 21 22 23

28 27 26

25

30 29 28 27 26

22

26

3

11

14

21 22

25 30

33

2 1 6 5

12

17

13

T1S

T2S

R12W R11W

Gabriel

San

Hondo

Rio

River

60

60

Norwalk

Rosemead

Blvd

Whittier Blvd

Washington Blvd

118 08' 118 06' 118 04' 118 02' 118

34

04'

34

02'

33

58'

34

0 2 MILES

0 2 KILOMETERS

Consolidated rocks

Unconsolidated deposits

EXPLANATION

Spreading ground

Whittier Narrows

Flood Control Basin

Narrows

Whittier

Montebello

Forebay

Rio Hondo

Coastal Basin

Spreading

Grounds

San Gabriel River

Coastal Basin

Spreading

Grounds

Puente Hills

Repetto Hills

605

5

10

Merced Hills

USGS Research

Field Site

San Jose Creek

Water

Reclamation

Plant

Figure 1. Location of the research field site in the Montebello Forebay, Los Angeles County, California.
Description of Study Area 5

DISTANCE FROM CENTER OF TEST BASIN, IN METERS

–20 40 60 0 20

DEPTH BELOW BOTTOM OF TEST BASIN, IN METERS

–3

0

3

6

9

12

15

18

WP3

WP4

WP5

WP1

WP2

WP8

WP7

WP6

Sampling ports

and location

Catwalk

Berm Berm

GP1-5

PR9

PR8

Test basin Desilting basin

Slope

PR10

PR11

Figure 2. Research field site with the PVC monitoring wells (PR8–PR11; PR14 and PR15, located 45.7 m north of the test basin, in the upgradient direction of 

ground-water flow, not shown), steel well points (WP1–WP8), and stainless-steel implants (GP1–GP5). Catwalk provides access to instrumentation during 

experiments; depth given in meters below the floor of the test basin. Direction of regional ground-water flow beneath the test basin is from left to right 

(Reichard and others, 2003).
6 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

Site Characterization

Core material was collected during the construction of the 

test basin at the research field site by driving a flame-sterilized, 

split-spoon core barrel through the bottom of the hole 

produced by hollow-stem augering. The core material was 

recovered at approximately 0.3-m intervals to a depth of about 

10.6 m below the floor of the test basin. A lithology log 

compiled from visual inspection indicates that soil beneath the 

test basin is fine to coarse, moderately sorted, grayish-brown 

sand. Measured grain-size distributions beneath the test basin 

confirmed predominantly medium (0.25 mm–0.50 mm) to 

coarse (0.50 m –1.00 mm) sand (fig. 3). Both the descriptive 

lithology and the measured grain-size distribution show the 

existence of a thin clay lens beginning about 9.4 m beneath the 

test basin. The lens may thin southward, or be of variable 

thickness, even over short distances at the research field site. 

Below the clay lens is a lower sand unit, which extends below 

the total depth of drilling (15.2 m) at the research site. 

Vertical hydraulic conductivities of core sections 

collected after the second recharge experiment ranged from 

0.25 to 26.7 m/d (Anders, 1997). The low value, found nearest 

the floor of the test basin, reflects accumulation of a thin layer 

of fine-grained, organic-rich sediment on the site floor. 

Although thin, and probably of variable thickness, this material 

exerts a strong influence on the rate at which percolation 

occurs during artificial recharge experiments. Higher values of 

hydraulic conductivity in the percolation zone beneath the test 

basin are likely to more closely approximate conditions in 

shallow parts of the subsurface beneath the research field site. 

Horizontal hydraulic conductivity of the subsurface beneath 

the research field site, determined from slug tests and analyzed 

using the computer program AQTESOLV with the BouwerRice straight-line solution for an unconfined aquifer (Geraghty 

and Miller, Inc., Reston, Virginia), yielded values between 

25.9 m/d and 38.1 m/d. 

Microbiological Changes During Recharge

Portions of the core material collected during the 

construction of the test basin at the research field site were 

placed in sterile polyethylene “Whirl-Pak” bags and stored at 

4οC until analyzed in the laboratory. The core samples were 

analyzed for fecal coliform bacteria by the membrane filter 

procedure and for nitrifying (ammonia- and nitrite-oxidizing), 

nitrate-reducing and denitrifying bacteria by the most probable 

number (MPN) method as described by Britton and Gresson 

(1987). 

Table 1 shows the distribution of selected bacteria in the 

core samples collected from beneath the test basin during 

construction. No fecal coliform bacteria were detected in the 

soil column. The ammonia-oxidizing bacteria were more 

abundant at shallower than at greater depths, and nitriteoxidizing bacteria were detected in about one-half the core 

samples. The nitrate-reducing and denitrifying bacteria were 

abundant throughout the soil column and their densities varied 

by as much as five orders of magnitude. 

Water samples collected during the second recharge 

experiment, which was conducted from April–June 1994, were 

analyzed for total and fecal coliform bacteria and for nitrifying, 

nitrate-reducing and denitrifying bacteria. The water samples 

were placed in sterile 250-mL bottles and sodium thiosulfate 

(Na2S2O3) was added to remove subsequent influence from 

chlorine during storage. The membrane filter procedure, as 

described by the American Public Health Association (1985), 

was used for the enumeration of total and fecal coliform 

bacteria. The nitrate-reducing and denitrifying bacteria were 

enumerated using a modified MPN method with six five-tube 

decimal (10X) dilutions (Britton and Gresson, 1987). The 

procedure to enumerate the nitrifying bacteria was further 

modified to include three five-tube 10X dilutions. 

Table 2 shows the distribution of selected bacteria in 

water samples collected as part of the second recharge 

experiment (April to June 1994): immediately before recharge, 

2 days after the second recharge experiment began, and more 

than 1 month after recharge was discontinued. The densities of 

total coliform bacteria increased by two orders of magnitude 

during the first 48 hours after the recharge experiment began, 

from none detected to greater than 300 colony-forming units 

per 100 mL (cfu/100 mL). After recharge was discontinued, 

the densities of total coliform bacteria returned to 

nondetectable levels. The data in table 2 also shows the 

buildup of fecal coliform soon after recharge began, and then 

a return to nondetectable levels after recharge was 

discontinued. This rapid increase in both total and fecal 

coliform bacteria from nondetectable levels in the soil column 

and water samples prior to artificial recharge using recycled 

water indicates direct physical transport with the percolating 

recycled water, rather than simple regrowth of preexisting 

bacteria. 

Nitrifying (ammonia- and nitrite-oxidizing) bacteria were 

detected in most water samples before, during, and after 

recharge. Densities increased at depths greater than 3 m, but 

increased only slightly at shallower depths, soon after 

recharge. Nitrate-reducing and denitrifying bacteria were 

found to be abundant in the recycled water itself, increased 

about an order of magnitude as the recycled water accumulated 

in the test basin itself, and then decreased by one-to-two orders 

of magnitude in the percolating water collected from beneath 

the test basin. The decrease could be the result of removal by 

soil or of die-off. Because nitrate-reducing and denitrifying 

bacteria appear to be abundant naturally in the soil as well as 

in the recycled water, evidence for their transport during 

recharge is inconclusive. 
Description of Study Area 7

10 1 0.1 0.01 0.001

PERCENT FINER THAN INDICATED SIZE

0

20

40

60

80

100

9.3-9.6

GRAIN SIZE, IN MILLIMETERS

Depth below bottom

of test basin,

in meters

0.3-0.7

0.8-1.2

1.2-1.5

1.5-1.7

1.7-1.9

1.9-2.1

2.1-2.4

2.6-2.9

3.0-3.5

3.5-3.9

4.0-4.3

9.6-9.7

9.8-9.9

10.0-10.2

10.4-10.6

8.5 (fill)

Figure 3. Grain-size distribution for core material from selected depths beneath the research field site, Los Angeles County, California.
8 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

Table 1. Distribution of selected bacteria in core samples collected during construction of the research field site, Los Angeles County, California

[Depth, in meters beneath the bottom of the test basin; m, meter; cfu/gm, colony-forming units per gram; MPN/gm, most probable number per gram; <, less than 

indicated value]

Depth

(m) Fecal coliform

(cfu/gm wet soil)

Ammonia-oxidizing

(MPN/gm wet soil)

Nitrite-oxidizing

(MPN/gm wet soil)

Nitratereducing/denitrifying

(MPN/gm wet soil) From To

0.84 1.19 0 930 230 93,000

1.22 1.47 0 2,300 2,300 210,000

1.47 1.78 0 230 <30 4,300

1.78 1.88 0 390 230 93,000

1.88 2.13 0 230 <30 9,300

2.13 2.44 0 230 <30 240,000

2.59 2.95 0 430 150 23,000

3.05 3.51 0 230 430 240,000

3.51 3.94 0 230 230 1,100,000

3.96 4.32 0 230 40 240,000

9.30 9.58 0 230 90 460,000

9.58 9.75 0 <30 <30 90

9.75 9.80 0 <30 <30 9,300

9.80 9.83 0 <30 <30 15,000

9.83 9.98 0 <30 <30 43,000

10.06 10.21 0 <30 <30 460,000

10.46 10.59 0 <30 <30 460,000
Description of Study Area 9

Table 2. Distribution of selected bacteria in water samples collected during the second recharge experiment: immediately before recharge, 2 days after 

recharge began, and more than 1 month after recharge was discontinued

[Depth, in meters beneath the bottom of test basin; m, meter; cfu, colony-forming units; MPN, most probable number; mL, milliliter; total coliform data given left 

of slash, fecal coliform data given right of slash; >, greater than indicated value; —, no data]

Depth

(m)

Total coliform/Fecal coliform Ammonia-oxidizing Nitrite-oxidizing Nitrate-reducing/denitrifying

Apr. 4 Apr. 6 Jun. 1 Apr. 4 Apr. 6 Jun. 1 Apr. 4 Apr.6 Jun. 1 Apr. 4 Apr. 6 Jun. 1

(cfu/100mL) (MPN/mL)

1.2 0/0 10/2 0/0 330 490 0 700 80 790 1,700 1,400 790

1.5 0/0 18/2 0/0 490 790 40 80 330 170 790 2,700 790

1.8 0/0 11/2 0/0 790 330 20 230 230 230 1,400 49,000 230

2.1 0/0 8/2 0/0 1,300 2,400 80 1,700 230 230 1,100 1,100 330

2.4 0/0 28/1 0/0 1,300 1,300 50 490 230 230 460 1,700 70

2.7 0/0 >300/18 0/0 0 490 0 20 140 50 130 33,000 700

3.0 0/0 19/6 0/0 0 490 0 20 80 80 4,900 2,400 340

7.6 0/0 9/0 0/0 0 0 230 0 20 230 4,900 700 1,700

Pond —/— >300/16 —/— — 24,000 — — 490 — — 24,000 —

Effluent —/— >300/— —/— — 2,400 — — 1,300 — — 23,000 —
10 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

Methods and Materials

Field Preparation

Before each tracer experiment was initiated, the soil 

surface of the test basin was disked to break up any hardpan 

that might have remained from previous spreading operations 

at the research field site. Throughout each experiment, 

measurements of temperature, pH, specific conductance, 

dissolved oxygen, dissolved organic carbon, and redox 

sensitive species such as nitrogen, iron, and manganese were 

obtained in order to determine the water quality in the test basin 

itself and in the subsurface beneath the research field site. 

All monitoring wells and steel well points were purged 

prior to the collection of water samples by removing three 

casing volumes using a submersible SP-300R sampling pump 

system (Fultz Pumps, Inc., Lewistown, Pennsylvania) until 

specific conductance, pH, and temperature measurements had 

stabilized. PFE-Teflon tubing (0.6-cm) was inserted into the 

casing and attached to peristaltic tubing to allow for continuous 

sampling throughout each experiment using peristaltic pumps. 

Water samples from GP1 through GP5 were collected through 

PFE-Teflon tubing (0.6-cm) attached to the ends of the 

stainless-steel implants using peristaltic pumps. 

Field measurements of pH and specific conductance were 

made using an Orion 250A meter with an Orion model 9106 pH 

combination electrode calibrated daily using pH 4, 7, and 10 

standards and a temperature-compensated conductivity meter 

(Orion model 124) calibrated daily against standard reference 

solutions. Water temperatures were measured using a handheld alcohol-filled thermometer. 

Water samples for analysis of common inorganic 

constituents and nutrients were pressure-filtered in the field 

through inline 0.45-mm polyether sulfone cartridge filters from 

Gelman Scientific. Aliquots for inorganic chemical analysis 

were dispensed into clear polyethylene bottles for storage after 

the bottle was rinsed three times. Bottles used for analysis of 

cations were acidified to approximately pH 2 by addition of 

nitric acid. Aliquots for nutrient analysis were distributed into 

125-mL, pre-rinsed, opaque, polyethylene bottles and placed 

on ice to minimize microbial alteration. Inorganic chemical and 

nutrient analyses were done by the USGS National WaterQuality Laboratory in Arvada, Colorado, using methods 

described generally by Fishman (1993), Timme (1994), and 

Struzeski and others (1996). 

Bromide Analysis 

Bromide, in the form of potassium bromide (Ameribrom 

Inc., New York, NY, photo grade), was chosen as the 

conservative tracer to track the recharge front using bromide 

electrodes, and to estimate dilution of the recycled water by soil 

moisture and (or) ground water during recharge. Bromide 

concentrations were measured in the field at several locations 

throughout the tracer experiments using Orion 250A meters 

with Orion model 9635 IonPlus bromide electrodes calibrated 

daily using prepared 1.0 mM, 0.1 mM, and 0.01 mM bromide 

standards. All water samples for bromide analysis were 

collected into 125-mL polyethylene bottles and bromide 

concentrations were measured at the USGS National WaterQuality Laboratory in Arvada, Colorado (first tracer 

experiment), or the USGS Geochemistry Laboratory in San 

Diego, California (second and third tracer experiments), using 

ion chromatography. 

Bacteriophage Assays 

 The Salmonella typhimurium phage, PRD1, was used 

during the first tracer experiment. The male-specific RNA 

coliphage, MS2, along with PRD1, was used during the second 

and third tracer experiments. These bacteriophage were chosen 

because similar bacteriophage are present in treated municipal 

wastewater and in recycled water used for recharge (Yanko and 

others, 1999). Furthermore, bacteriophage have been used 

extensively in virus transport studies and are considered to be 

good model viruses because they are less absorbed than most 

pathogenic viruses and are relatively persistent during transport 

through the subsurface (Bales and others, 1997; Jin and others, 

1997; Ryan and others, 1999; Schijven and others, 1999). 

Water samples for bacteriophage analysis during the first and 

second tracer experiment were collected into sterile 100-mL 

bottles and stored at 4οC until analysis was conducted at the 

CSDLAC microbiology laboratory. During the third tracer 

experiment, water samples for bacteriophage analysis were 

collected into different-sized (125 mL and 10 L) sterile bottles. 

The large volume samples collected from WP7, PR9, and PR11 

were refrigerated and analyzed within a couple of days. Thirty 

percent sterile beef extract was added to each sample size of 

200 mL or less and the samples were frozen until analyzed at 

the CSDLAC microbiology laboratory. The protein in the beef 

extract protects the virus during the freezing process. This was 

confirmed in a previous investigation (James L. Jackson, 

County Sanitation Districts of Los Angeles County, 

unpub. data, 2000).
Methods and Materials 11

Bacteriophage concentrations were measured using either 

the double-agar-layer assay procedure or a MPN procedure. 

Samples estimated to have bacteriophage concentrations less 

than 1 plaque-forming unit per milliliter (PFU/mL) were 

analyzed using a MPN procedure (Kott, 1966) or a modified 

MPN procedure (Yanko and others, 1999). 

Trypticase soy broth (TSB) (Difco), TSB (Difco) soft 

agar (containing 0.05 percent 1N CaCl2) and trypticase soy 

agar (TSA) (Difco) bottom agar were used for analyzing PRD1 

bacteriophage using Salmonella typhimurium LT2 (ATCC 

#15277) as the host bacteria for all three tracer experiments. 

MS2 bacteriophage were analyzed for the second and third 

tracer experiments using TSB (Difco), TSB (Difco) soft agar 

(containing 0.05 percent 1N CaCl2), TSA (Difco) bottom agar, 

E. coli F-

 amp (ATCC #700981) as the host bacteria, and the 

same concentration of antibiotics as described by 

Debartolomeis and Cabelli (1991). 

The double-agar-layer assay method was performed by 

preparing a mixture of 1 mL of host bacteria, 4 mL of molten 

soft agar (45οC), and 1 mL of sample. The mixture was gently 

vortexed and poured onto the appropriate plating medium. 

Plates were incubated at 37οC for 24 hours. The concentrations 

were determined by counting the number of plaques on each 

plate. Plates were made in duplicate and the concentration was 

averaged from the plaques counted on each plate. The doubleagar-layer assay, used duplicate for this study had a detection 

limit of 0.5 PFU/mL.

The MPN method was set up in a 5-tube, 3-dilution assay. 

The method consisted of inoculating 10, 1, and 0.1 mL of 

sample into appropriate broth (containing 1.25 percent 4M 

MgCl2) and adding 0.1 mL of appropriate host bacteria to each 

tube. The tubes were incubated at 37οC for 24 hours. Double 

strength (2X) media was used for the 10-mL inocula. 

For the large-volume modified MPN procedure, 11X 

medium was substituted with 5.5X broth sterilized in the 

autoclave instead of the medium that was filter sterilized, as 

described in draft EPA Method 1601 (May 1999). The inocula 

included 1 L, 100 mL, and 10 mL set in a 5-bottle/tube, 

3-dilution assay with 5.5X broth used for the 1 L and 100 mL 

inocula, and double-strength broth used for the 10-mL inocula 

with 1.25 percent 4M MgCl2 added to each water sample. Host 

bacteria was added in the amount of 10 mL to each 1 L bottle, 

1 mL to each 100-mL bottle, and 0.1 mL to each 10-mL tube. 

Tubes/bottles were incubated at 37οC for 48 hours. After 

incubation, a 100 μL aliquot from each tube/bottle was spotted 

onto a plate (or plates) of freshly prepared lawns of appropriate 

host to confirm the presence of phage, as described by Kott 

(1966). Up to 5 tubes were spotted on a single plate. Lawns 

were prepared by the addition of 0.5 mL of log-phage host to 

3-mL soft agar and poured onto the respective plating media. 

Plates were incubated at 37οC overnight and observed for 

plaque formation. An MPN was computed from the resulting 

positive/negative bottles. The modified MPN method used for 

this study had a detection limit of 0.02 MPN PFU/mL. 

Model Development

Assuming kinetically controlled irreversible attachment 

to the porous media grains, collision efficiencies were 

calculated based on the relative breakthrough of each 

bacteriophage during the second and third tracer experiments 

(Harvey and Garabedian, 1991). The relative breakthrough, 

RB, the ratio of the time-integrated mass of each bacteriophage 

(MS2 and PRD1) relative to that of a conservative tracer 

(bromide), is defined as:

(1)

where 

The RB can be determined from experimental data by 

integrating the area under the corresponding normalized 

breakthrough curves using the trapezoid rule.

From the relative breakthroughs, the collision efficiency, 

α, can be calculated for MS2 and PRD1 during the tracer 

experiments from the colloid-filtration model and assuming 

that the bacteriophage and bromide enter the system as a pulse 

input (Harvey and Garabedian, 1991) by the following:

(2)

where 

the longitudinal dispersivity is

C0 and Br0 are the initial bacteriophage and bromide 

concentrations, respectively,

C(t) and Br(t) are the corresponding concentrations at a 

sampling point at some time t after the 

tracer experiment began, and 

t0 and tf are the beginning times and ending times of 

each breakthrough curve, respectively.

dp is the average grain diameter of the porous medium, 

θ is the porosity of the porous medium,

η is the overall single collector efficiency for favorable 

deposition,

lz is the distance from the injection point to the sampling 

point, and 

RB

Br0

C0

-------- C t( )

Br t( ) ------------ t0

tf

∫ = dt

α

dp 1 2 αL lz ( ) ⁄ lnRB 2 { } [ ] – – 1

6 1( )ηα – θ L

= -------------------------------------------------------------------------

αL D De = ( ) – ⁄ U
12 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

where 

Owing to the small size of each bacteriophage and in the 

absence of double layer interaction energy, the overall single 

collector efficiency, η, can be calculated with only the 

convective diffusion contribution as (Pieper and others, 1997):

 (3)

where 

(4)

where ε = (1 − θ) 1/3.

The parameter values of U and D were determined by 

fitting the experimental bromide breakthrough curves using the 

computer program CXTFIT, which estimates solute-transport 

parameters using a nonlinear least-squares parameter 

optimization method (Toride and others, 1995). 

Virus Fate and Transport During 

Recharge 

Recharge experiments with recycled water conducted at a 

small research field site constructed adjacent to the large 

recharge facility in the Montebello Forebay of Los Angeles 

County, California, indicated that bacteria can move through 

the soil with the percolating recycled water (Anders, 1997; 

Anders and Schroeder, 2003). These conclusions formed the 

basis for three field-scale tracer experiments using bacterial 

viruses (bacteriophage) PRD1 and MS2 as surrogates for 

human viruses and bromide as a conservative tracer. 

Water Quality

Water-quality data for selected wells at the research field 

site collected during the three tracer experiments is contained 

in Appendix A. The water temperature in the test basin during 

the three tracer experiments ranged from 27.4οC to 29.0οC. 

Specific conductance and pH measurements taken from the test 

basin during the three experiments ranged from 934 μS/cm to 

slightly less than 1,100 μS/cm and from about 6.9 to 7.2 pH 

units, respectively. Background water temperature, specific 

conductance, and pH, as measured from water samples 

collected from beneath the test basin prior to any delivery of 

bacteriophage and bromide, ranged from about 21.1οC to 

21.6οC, from 632 μS/cm to 841 μS/cm, and from 7.3 to 7.6 pH 

units, respectively. These values indicate chemical conditions 

at the research field site changed very little throughout each 

experiment and are similar to those observed during previous 

recharge experiments at the research field site (Anders, 1997; 

Anders and Schroeder, 1997; Schroeder, 2003). 

Results from Tracer Experiments

First Tracer Experiment, August 1997

The first tracer experiment was carried out over a 2-day 

period in August 1997. Prior to starting the experiment, the test 

basin was filled to a depth of about 0.6 m with recycled water. 

Delivery of recycled water to the test basin was halted briefly, 

and the surface of the water in the test basin was sprayed over 

a 30-min period with concentrated solutions of bacteriophage 

and bromide containing 4.8 × 1012 PFU of PRD1 and 18 kg of 

bromide. Delivery of recycled water (without addition of 

bacteriophage and bromide) to the test basin was resumed after 

about 3.5 hours. More than 100 water samples were collected 

from 1.5 m below the floor of the test basin (WP1) and 3.0 m 

below the floor of the test basin (WP2) [depths averaged over 

the screened interval] and from the test basin itself (PR12) for 

bacteriophage assays over the 2-day sampling period. 

Bacteriophage PRD1 concentrations in water samples 

collected during the first tracer experiment are contained in 

Appendix B. Samples of ponded water collected from the 

perimeter and the center of the test basin indicated that bromide 

and bacteriophage were reasonably well mixed in the test basin. 

Initial concentrations for PRD1 and bromide averaged 4.8 ±

0.35 × 104 PFU/mL and 77.8 ± 6.0 mg/L, respectively. The 

observed breakthrough curves for both PRD1 and bromide at 

WP1 indicate that PRD1 reached a maximum concentration of 

140 PFU/mL shortly after the start of the experiment and that 

the bacteriophage peak coincided with the bromide peak 

(fig. 4). No bacteriophage were detected at WP2.

D is the hydrodynamic dispersion coefficient,

De is the effective molecular-diffusion coefficient, and

U is the average interstitial velocity. 

kB is the Boltzman constant,

T is the solute temperature in Kelvin

μ is the fluid viscosity, 

dv is the virus diameter,

q=Uθ is the specific discharge or approach velocity, and 

As is Happel's sphere-in-cell model correction factor 

defined as:

η 0.9As

1

3

-- kBT

2

3

--

μdpdvq = -----------------

As

1 ε

5 –

1 1.5 – ε 1.5ε

5

ε

6

+ –

= -------------------------------------------------
Virus Fate and Transport During Recharge 13 BROMIDE CONCENTRATION, IN MILLI

GRAMS PER LITER

0

0

20

10

40

20

60

30

80

40

100

120

PHA

GE CONCENTRATION,

IN PLAQUE-FORMIN

G UNITS PER MILLILITER

105

104

103

102

101

100

PRD1 (WP1)

Br (WP1)

PRD1 (PR12)

TIME SINCE TRACER EXPERIMENT BEGAN, IN HOURS

Figure 4. Bacteriophage PRD1 concentrations in water samples collected from the test basin (PR12; open circles) and WP1 (solid circles) and bromide 

concentrations in water samples collected from WP1 (solid squares) during the first tracer experiment, August 1997, from a research field site located in Los 

Angeles County, California.
14 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

Second Tracer Experiment, August–September 1998

During the second field-scale tracer experiment, 

bacteriophage MS2 was added along with bacteriophage 

PRD1 and bromide. With a depth of about 1.2 m, the volume 

of recycled water in the test basin was maintained at 

approximately 473 m3 by addition of the recycled water at a 

delivery rate of about 1,063 m3/d. The initial seeding of the test 

basin was accomplished in the same manner as the first tracer 

experiment. The surface of the water in the test basin was 

sprayed with solutions containing 8.5 x 1011 PFU of PRD1, 8.5 

× 1013 PFU of MS2, and 49 kg of bromide. After the initial 

seeding of the test basin was completed, 4.7 × 1012 PFU of 

PRD1, 6.0 × 1013 PFU of MS2, and 11 kg of bromide were 

injected, using peristaltic pumps, directly into the feed pipe 

delivering the recycled water to the test basin. The injection 

process lasted several hours. After the metered injection was 

completed, delivery of recycled water to the test basin was 

halted. Delivery of recycled water was resumed without 

addition of bacteriophage and bromide after about 23 hours. 

During the 9-day experiment, water samples were collected 

from the same points as during the first experiment, and from 

WP7, GP1 through GP3, and PR8 through PR11. 

Bromide concentrations in water samples collected 

during the second tracer experiment are contained in 

Appendix C. Bacteriophage MS2 and PRD1 concentrations 

during the second tracer experiment are contained in Appendix 

D. During the period when no recycled water was being 

delivered to the test basin, 24 grab samples were collected 

from 4 locations around the perimeter and near the center of the 

test basin to ascertain the degree of mixing (spatial 

heterogeneity) of the bacteriophage and bromide in the ponded 

water. The average concentrations in the 24 samples were 

determined to be 2.4 ± 1.1 × 104 PFU/mL for PRD1, 2.4 ± 1.4 

× 105 PFU/mL for MS2, and 107.0 ± 28.0 mg /L for bromide. 

Bromide arrived at WP1 after about 4 hours and at WP2 after 

about 8 hours (fig. 5). The bromide breakthrough curves for 

WP7, PR9, and PR11 show that bromide arrived at the greater 

depths after about 2 days, with the bromide arriving at WP7 

and PR11 beneath the berm of the test basin slightly before 

arriving at PR9 directly beneath the center of the test basin. 

The bromide breakthrough curves also indicated a 70 percent 

reduction [dilution by antecedent soil moisture and (or) 

regional ground water] in the maximum bromide concentration 

arriving at PR9. 

The bacteriophage MS2 arrived at WP1 at about the same 

time as did bromide, and reached a maximum concentration 

slightly greater than 6 ×104 PFU/mL (fig.6). The arrival time 

for MS2 at WP2 was about 8 hours, and the maximum 

concentration was reduced to about 4 × 104 PFU/mL. The 

movement of bacteriophage PRD1 was coincident with that of 

MS2, arriving at WP1 slightly before 4 hours and at WP2 after 

about 8 hours (fig.7). However, the maximum concentration of 

PRD1 of almost 3 × 102 PFU/mL at WP2 was slightly greater 

than the maximum concentration achieved at WP1 and 

suggests no additional removal occurred after 1.5 m of 

subsurface transport. PRD1 was also detected at greater 

depths, although the results were presence/absence only. No 

bacteriophage or bromide were detected at PR8 or PR10, 

below the thin clay unit beginning about 9.4 m beneath the 

bottom of the test basin, during the second tracer experiment. 

It should be noted here that previous recharge experiments 

conducted at the research field site have shown that no 

displacement of preexisting water occurs below the clay lens 

until a few days after recharge from the test basin begins 

(Schroeder and others, 2003). 

Third Tracer Experiment, August 2000

Because the third tracer experiment was conducted to 

confirm the results obtained from the second tracer 

experiment, the seeding procedure used for the second tracer 

experiment was repeated. During the third recharge 

experiment, the depth and volume of recycled water in the test 

basin were 2.0 m and about 1,000 m3, respectively. Solutions 

containing 5 × 1013 PFU of PRD1, 5.3 × 1014 PFU of MS2, 

and 72 kg of bromide were applied to the test basin during the 

initial seeding and injection period. During the 7-day tracer 

experiment, water samples were collected from the same 

sampling points as during the second experiment, and from 

GP4 and GP5. No water samples were collected from PR8 and 

PR10 during the third tracer experiment.

Bromide concentrations in water samples collected 

during the third tracer experiment are contained in Appendix 

E, and bacteriophage MS2 and PRD1 concentrations are 

contained in Appendix F. The average concentrations of 

bacteriophage and bromide in the test basin were determined to 

be 8.9 ± 4.8 × 103 PFU/mL for PRD1, 6.0 ± 2.6 × 104 PFU/mL 

for MS2, and 85.0 ± 5.0 mg/L for bromide. Bromide arrived at 

WP1 after about 4 hours and at WP2 after about 8 hours 

(fig. 8). The bromide spikes at the shallower depths are due to 

overestimating the volume of recycled water present in the test 

basin and (or) incomplete mixing in the test basin during the 

first few hours of the experiment. The bromide breakthrough 

curves for WP7, PR9, and PR11 show that bromide arrived at 

these greater depths after about 1.2, 2.0, and 1.7 days, 

respectively, with less than 50 percent reduction in the 

maximum bromide concentration. The bacteriophage MS2 

arrived at WP1 at about the same time as did bromide, and 

reached a maximum concentration slightly greater than 1 × 103

PFU/mL (fig. 9). The arrival time for MS2 at WP2 was greater 

than 20 hours, and the maximum concentration was about 

1 × 103 PFU/mL. The MS2 breakthrough curves at WP1 and 

WP2 also indicated that the concentration of MS2 remained 

above about 5 × 101 PFU/mL throughout the first 6 days of the 

experiment. The breakthrough curves for PRD1 are shown for 

GP1 and GP2, since during the third tracer experiment no 

PRD1 was found below 1.0 m at a concentration greater than 

the detection limit (fig. 10). 
Virus Fate and Transport During Recharge 15

0

0123456

50

100

150

200

250

300

TIME SINCE TRACER EXPERIMENT BEGAN, IN DAYS

BROMIDE CONCENTRATION, IN MILLI

GRAMS PER LITER

WP1 (1.5 meters, center)

WP2 (3.0 meters, center)

WP7 (3.0 meters, berm)

PR9 (7.6 meters, center)

PR12 (test basin)

PR11 (7.6 meters, berm)

Figure 5. Bromide concentrations during the second tracer experiment, August–September 1998, from a research field site located in Los Angeles County, 

California.
16 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

z

0123456

TIME SINCE TRACER EXPERIMENT BEGAN, IN DAYS

MS2 CONCENTRATION,

IN PLAQUE-FORMIN

G UNITS PER MILLILITER

105

106

104

103

102

101

100

WP1 (1.5 meters)

WP2 (3.0 meters)

PR12 (test basin)

Figure 6. Bacteriophage MS2 concentrations during the second tracer experiment, August–September 1998, from a research field site located in Los Angeles 

County, California. 
Virus Fate and Transport During Recharge 17

WP1 (1.5 meters)

WP2 (3.0 meters)

PR12 (test basin)

0123456

TIME SINCE TRACER EXPERIMENT BEGAN, IN DAYS

PRD1 CONCENTRATION,

IN PLAQUE-FORMIN

G UNITS PER MILLILITER

105

106

104

103

102

101

100

Figure 7. Bacteriophage PRD1 concentrations during the second tracer experiment, August–September 1998, from a research field site located in Los Angeles 

County, California.
18 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

0

0123456

50

100

150

200

250

300

TIME SINCE TRACER EXPERIMENT BEGAN, IN DAYS

BROMIDE CONCENTRATION, IN MILLI

GRAMS PER LITER

WP1 (1.5 meters, center)

WP2 (3.0 meters, center)

WP7 (3.0 meters, berm)

PR9 (7.6 meters, center)

PR12 (test basin)

PR11 (7.6 meters, berm)

Figure 8. Bromide concentrations during the third tracer experiment, August 2000, from a research field site located in Los Angeles County, California.
Virus Fate and Transport During Recharge 19

0123456

TIME SINCE TRACER EXPERIMENT BEGAN, IN DAYS

MS2 CONCENTRATION,

IN PLAQUE-FORMIN

G UNITS PER MILLILITER

105

106

104

103

102

101

100

WP1 (1.5 meters)

WP2 (3.0 meters)

PR12 (test basin)

Figure 9. Bacteriophage MS2 concentrations during the third tracer experiment, August 2000, from a research field site located in Los Angeles County, 

California.
20 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

0123456

TIME SINCE TRACER EXPERIMENT BEGAN, IN DAYS

PRD1 CONCENTRATION,

IN PLAQUE-FORMIN

G UNITS PER MILLILITER

105

106

104

103

102

101

100

GP1 (0.3 meters)

GP2 (0.6 meters)

PR12 (test basin)

Figure 10. Bacteriophage PRD1 concentrations during the third tracer experiment, August 2000, from a research field site located in Los Angeles County, 

California.
Virus Fate and Transport During Recharge 21

Inactivation Rates

The rate of bacteriophage inactivation in the recycled 

water independent of any processes occurring in the subsurface 

was determined from measurements on water in the pond itself 

during the second and third tracer experiments. Assuming that 

virus inactivation is a first-order process (Yates and others, 

1985), the rate of bacteriophage inactivation can be determined 

by linear-regression analysis of the observed normalized 

bacteriophage log-concentrations. For the second tracer 

experiment, during the 16-hour period when no additional 

recycled water or bacteriophage were being delivered to the 

test basin, inactivation rates were 0.07 hr-1 (r2 = 0.94) for MS2 

and 0.02 hr-1 (r2 = 0.36) for PRD1 (fig. 11). These values 

indicate that the inactivation rate for MS2 was higher than for 

PRD1. However, for the 5-hour period when no recycled water 

or bacteriophage were delivered to the test basin during the 

third tracer experiment, inactivation rates were 0.02 hr-1

(r2 = 0.02) and 0.2 hr-1 (r2 = 0.44) for MS2 and PRD1, 

respectively (fig. 12). It is not clear what caused the increase in 

the inactivation rate of PRD1 during the third experiment. 

Temperature, an important factor that controls the degree of 

virus inactivation, was similar between the tracer experiments. 

Other factors that are known to influence the rate of 

inactivation in aquatic systems, such as Brownian coagulation 

of viruses (Grant, 1994) and (or) microbial activity (Janson and 

others, 1989) were not monitored. 

It should be noted here that Sim and Chrysikopoulos 

(1996) have proposed that the inactivation rate coefficients 

should be time-dependent, which may explain the lower 

correlations. They suggested that virus transport data collected 

in the vicinity of the source of contamination at early times are 

most reliable for estimation of inactivation rate coefficients, 

and temporally variable inactivation rate coefficients can 

significantly affect the predicted virus migration in porous 

media. However, the inactivation rate coefficients measured 

during the tracer experiments can provide a conservative 

estimate for the adequate soil-retention time requirement for 

pathogen removal.

Attenuation Rates

In order to correct for the effect of dilution by antecedent 

soil moisture or regional ground water, bacteriophage 

concentrations were normalized with respect to bromide 

concentrations for samples collected during the second and 

third tracer experiments. Only a few bromide samples were 

analyzed during the first tracer experiment. For the second 

experiment, the bacteriophage to bromide ratios were 

calculated for samples from the test basin itself, and from 

0.3, 0.6, 1.0, 1.5, and 3.0 m below the floor of the test basin. 

The resulting bacteriophage to bromide ratio plots at 3, 6, 9, 

and 21 hours after the addition of bacteriophage and bromide 

show the initial removal of MS2 and PRD1 during infiltration 

through the floor of the test basin at the soil-water interface, 

and then subsequent removal as the bacteriophage move 

through the percolation zone in the shallow part of the aquifer 

(fig. 13). Regression analysis of almost 125 bacteriophage to 

bromide ratios collected during the second tracer experiment 

was used to estimate the attenuation rates of MS2 and PRD1 

during aquifer recharge. The attenuation rates are defined as the 

logarithmic reduction in the bacteriophage to bromide ratio, 

expressed as log10 (Cvirus/Cbromide), during percolation of the 

amended recycled water beneath the test basin. Regression 

analysis of the data collected during the second experiment 

yielded an attenuation rate of 0.37 log10 units per meter for 

MS2 and 0.55 log10 units per meter for PRD1 (fig.14). The low 

correlations, r2 = 0.14 (n = 70) and r2 = 0.22 (n = 54) for MS2 

and PRD1, respectively, indicate substantial deviations from 

the regression line. Schijven and others (1999) suggested that 

such deviations are probably due to subsurface heterogeneities 

and (or) analytical variability.

For the third tracer experiment, regression analysis of data 

collected from the test basin itself and from 0.3, 0.6, 1.0, 1.2, 

1.5, and 3.0 m below the floor of the test basin yielded an 

attenuation rate of 0.83 log10 units per meter and r2 of 0.32 

(n = 162) for MS2 and an attenuation rate of 3.0 log10 units per 

meter and r2 of 0.71 (n = 53) for PRD1 (fig. 15). The third 

tracer experiment showed an increase in the attenuation rates 

and higher correlations for both MS2 and PRD1, especially for 

PRD1, due to increased removal and (or) inactivation. 

Collision Efficiency 

The average interstitial velocity, U, and the hydrodynamic 

dispersion coefficient, D, were determined by fitting the 

experimental bromide breakthrough curves using the computer 

program CXTFIT. During the second experiment, 

U = 7.17 × 10−5 m/s and D = 1.34 × 10−6 m2/s at 1.5 m beneath 

the test basin. At 3.0 m, U = 8.35 × 10−5 m/s and 

D = 1.18 x 10−6 m2/s. During the third experiment, 

U = 8.52 × 10−5 m/s and D = 1.38 × 10−6 m2/s at 1.5 m and 

U = 7.11 × 10−6 m/s and D = 1.05 × 10−6 m2/s at 3.0 m. The 

slight increase in fluid velocities with depth during the second 

experiment and slight decease with depth during the third 

experiment indicate different hydraulic conditions existed 

beneath the test basin during these two experiments. 
22 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

MS2

 = 0.07 hr-1, r2 = 0.94

 = 0.02 hr-1, r2 = 0.36

PRD1

5

-2.0

-1.5

0.5

0

-0.5

-1.0

10 15 20 25

TIME SINCE TRACER EXPERIMENT BEGAN, IN DAYS

ln(C/C0)

Figure 11. Normalized log-concentrations of MS2 (solid circles) and PRD1 (solid squares) in the test basin as a function of time for the second tracer 

experiment, August–September 1998. The slope of the fitted lines (solid line for MS2, and dashed line for PRD1) represents the corresponding inactivation rate 

coefficients, λ, for bacteriophage MS2 and PRD1. Shaded area is 16-hour period when no recycled water or tracer was being delivered to the test basin, Los 

Angeles County, California.
Virus Fate and Transport During Recharge 23

MS2

 = 0.02 hr-1, r2 = 0.02

 = 0.2 hr-1, r2 = 0.44

PRD1

5

-2.0

-1.5

0.5

0

-0.5

-1.0

10 15 20 25

TIME SINCE TRACER EXPERIMENT BEGAN, IN DAYS

ln(C/C0)

Figure 12. Normalized log-concentrations of MS2 (solid circles) and PRD1 (solid squares) in the test basin as a function of time for the third tracer experiment, 

August 2000. The slope of the fitted lines (solid line for MS2, and dashed line for PRD1) represents the corresponding inactivation rate coefficients, λ, for 

bacteriophage MS2 and PRD1. Shaded area is 5-hour period when no recycled water or tracer was being delivered to the test basin, Los Angeles County, 

California.
24 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

0123 0123

PHA

GE TO BROMIDE RATIO, IN PLAQUE-FORMIN

G UNITS PER MILLI

GRAM

105

106

107

104

103

102

101

100

105

106

107

104

103

102

101

100

DEPTH BELOW BOTTOM OF TEST BASIN, IN METERS

3 HOURS SINCE TRACER EXPERIMENT BEGAN 6 HOURS SINCE TRACER EXPERIMENT BEGAN

9 HOURS SINCE TRACER EXPERIMENT BEGAN

MS2

MS2

MS2

MS2

PRD1

PRD1

PRD1

PRD1

21 HOURS SINCE TRACER EXPERIMENT BEGAN

Figure 13. Bacteriophage to bromide ratio plots for the test basin (open symbols) and selected depths beneath the test basin (solid symbols) at 3, 6, 9, and 21 

hours after the addition of bacteriophage and bromide during the second tracer experiment, August–September 1998, from a research field site located in Los 

Angeles County, California.
Virus Fate and Transport During Recharge 25

0 1 2 3456

PHA

GE TO BROMIDE RATIO, IN PLAQUE-FORMIN

G UNITS PER MILLI

GRAM

105

106

107

104

103

102

101

100

105

106

107

104

103

102

101

100

DEPTH BELOW BOTTOM OF TEST BASIN, IN METERS

MS2

-0.37 log10 units m-1

r2 = 0.14

n = 70

-0.55 log10 units m-1

r2 = 0.22

n = 54

PRD1

Figure 14. Attenuation rates, defined as the logarithmic reduction in the bacteriophage to bromide ratio (solid line), for MS2 (solid circles) and PRD1 (solid 

squares) during the second tracer experiment August–September 1998, from a research field site located in Los Angeles County, California. 
26 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

0 1 2 3456

PHA

GE TO BROMIDE RAITO, IN PLAQUE-FORMIN

G UNITS PER MILLI

GRAM

105

106

107

104

103

102

101

100

105

106

107

104

103

102

101

100

DEPTH BELOW BOTTOM OF TEST BASIN, IN METERS

MS2

-0.83 log10 units m-1

r2 = 0.32

n = 162

-3.0 log10 units m-1

r2 = 0.71

n = 53

PRD1

Figure 15. Attenuation rates, defined as the logarithmic reduction in the bacteriophage to bromide ratio (solid line), for MS2 (solid circles) and PRD1 (solid 

squares) during the third tracer experiment, August 2000, from a research field site located in Los Angeles County, California.
Virus Fate and Transport During Recharge 27

The RBs (equation 1) for MS2 after 1.5 m and 3.0 m of 

transport were 3.35 × 10−2 and 1.70 × 10−2, respectively, for 

the second tracer experiment, and 4.33 × 10−3 and

7.35 × 10−4, respectively, for the third experiment. The RBs for 

PRD1 after 1.5 m and 3.0 m of transport were 1.97 × 10−3 and 

3.43 × 10−3, respectively, for the second tracer experiment. 

Since measured PRD1 concentrations were never greater than 

the detection limit below 1.0 m during the third tracer 

experiment, RBs were determined from data for 0.3 m and 0.6 

m of transport beneath the test basin. The corresponding RBs 

for PRD1 during the third tracer experiment were 1.99 × 10−2

at 0.3 m and 1.51 × 10−4 at 0.6 m. 

The collision efficiency (equation 2) was determined for 

each bacteriophage during the second and third tracer 

experiments with the longitudinal dispersivity, αL, calculated 

from fitted U and D values, the overall single collector 

efficiency, η, obtained from equation 3 and assigning a 

porosity, θ, of 0.3. The αL values ranged from 0.014 to 

0.019 m and indicate that the degree of soil formation 

heterogeneity beneath the test basin is slight. Table 3 contains 

additional parameter values used to calculate collision 

efficiencies for MS2 and PRD1 during the second and third 

tracer experiments. The α values for MS2 after 1.5 m and 3 m 

of transport were 1.37 × 10−3 and 8.94 × 10−4, respectively, 

during the second tracer experiment, and 2.51 × 10−3 and 

1.44 × 10−3, respectively, during the third experiment. The α

values for PRD1 during the second tracer experiment were 

4.78 × 10−3 and 2.30 × 10−3 after 1.5 m and 3.0 m of transport, 

respectively. During the third tracer experiment, α values were 

7.56 × 10−1 and 1.05 × 10−1 after 0.3 and 0.6 m of transport. 

The α values for PRD1 after 0.6 m of transport during the third 

experiment were not determined because PRD1 was only 

measured at the detection limit. 

The collision efficiency for both bacteriophage indicates 

attachment conditions were more favorable for PRD1 than for 

MS2 during the tracer experiments. The more favorable 

attachment conditions (higher collision efficiency) for 

bacteriophage PRD1 are due to its lipid-containing structure 

and higher hydrophobicity, whereas a more hydrophilic virus 

such as MS2 behaves more conservatively (Kinoshita and 

others, 1993). For comparison, collision efficiencies have been 

reported in the literature under different physiochemical and 

hydrologic conditions. Pieper and others (1997) reported that 

α = 1.3 × 10−2 in an uncontaminated aquifer zone and 

α = 1.4 × 10−3 in a contaminated zone. The lower collision 

efficiency (less favorable attachment conditions) in the 

contaminated zone was attributed to the presence of high 

dissolved organic matter that enhances bacteriophage 

transport. Schroeder and others (2003) reported dissolved 

organic carbon concentrations of almost 10 mg/L in recycled 

water at the research field site. 

Deborde and others (1999) calculated α = 4.0 × 10−3 for 

MS2 and α = 1.4 × 10−2 for PRD1 in a gravel-dominated 

floodplain aquifer. Although these α values are equal in 

magnitude to those obtained in our study, greater dp values of 

1.25 mm (coarse sand) and 12.0 mm (medium pebbles) at their 

site suggest less favorable attachment conditions existed due to 

higher ground-water velocities and lower specific 

conductance. Schijven and others (1999) studied the removal 

of viruses by dune recharge and found that α values ranged 

from 1.4 x 10−3 to 2.7 × 10−4 for MS2 and 2.4 × 10−3 to

4.3 × 10−4 for PRD1. Their very low α values reflect highly 

unfavorable conditions for attachment and are consistent with 

the concept that in sandy soils with pH values of 7.3–8.3, 

electrostatic repulsion is important in restricting attachment 

(Bales and others, 1993). Considering the slight difference in 

pH values reported by Schijven and others (1999) and 

Schroeder and others (2003), as well as the higher velocities 

during aquifer recharge and the presence of organic matter in 

recycled water, one would expect less-favorable conditions for 

attachment should have existed at the research site of our 

study. 

Table 3. Parameter values used to calculate collision efficiencies for MS2 and 

PRD1 during the second and third tracer experiments in Los Angeles County, 

California

[Parameters: kB, Boltzman constant; T, solute temperature; μ, fluid viscosity; dv, 

virus diameter; dp, average grain diameter; θ, porosity; As, Happel’s sphere-in-cell 

model correction factor, where ε = (1-θ)

1/3; Units: kg, kilogram; m, meter; s, 

second; K, degrees Kelvin]

Parameter Values Units

kB 1.38 × 10−23 (kg⋅m2)/(s2⋅K)

T 298 K

μ 8.91 × 10−4 kg/(m⋅s)

dp 2.5 × 10−4 m

dv 2.5 × 10−8 (MS2) m

6.2 × 10−8 (PRD1) m

θ .3

ε .89

As 75.5
28 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

The increased collision efficiency during the third tracer 

experiment for MS2 and PRD1 at the research field site, 

especially for PRD1, may be explained by changes in the 

attachment characteristics of each bacteriophage for the 

conditions present during the experiment. However, factors 

like temperature and ground-water quality that could affect the 

degree of attachment have been shown to be similar between 

tracer experiments, while other factors, such as viral surface 

properties or sediment surface charges, are not expected to 

change between experiments. 

Another possible explanation for the increased collision 

efficiencies (more favorable attachment conditions) at the 

research field site is due to alterations in the surface structure 

as well as the porosity of the filtering media during the recharge 

experiment. This explanation seems reasonable considering 

the changes in water flux and hydraulic conductivities that can 

occur over time during artificial recharge because of the 

presence of entrapped air, sealing of the soil surface, and the 

effect of biofilms sealing the pores within the wetted zones. 

Furthermore, such an explanation would be consistent with the 

increased attenuation rates during the third tracer experiment. 

Summary and Conclusions

The first tracer experiment established the feasibility of 

conducting such experiments under actual recharge conditions 

using recycled water seeded (augmented) with high 

concentrations of bacteriophage and bromide as tracers. On the 

basis of the results of the first tracer experiment, a second tracer 

experiment was designed to measure more precisely the fate 

and transport of surrogates for human viruses under actual 

recharge conditions. The third tracer experiment was 

completed to confirm the results obtained from the second 

tracer. 

The attenuation rates for MS2 and PRD1 during the 

second and third tracer experiments indicate that rapid 

reduction occurs in the concentration of bacterial viruses 

released into the environment with recycled water during 

aquifer recharge. Furthermore, these tracer experiments 

indicate that adsorption, not inactivation, is the predominant 

removal mechanism for viruses during aquifer recharge.

Collision efficiencies for MS2 and PRD1 confirm that 

favorable attachment conditions existed for both 

bacteriophage, especially for PRD1. The increased collision 

efficiencies during the third tracer experiment are explained by 

changes in the inactivation rates and (or) attachment 

characteristics of each bacteriophage for the conditions present 

during the experiment although factors such as temperature, 

specific conductance, and pH that could affect the degree of 

virus inactivation and attachment were determined to be 

similar between experiments. Furthermore, factors such as 

viral surface properties or sediment surface charges are not 

expected to change between experiments. A plausible 

explanation is that different attachment conditions between 

experiments were created by temporal changes in water flux 

and hydraulic conductivities beneath the test basin. 

Therefore, additional studies are needed to identify how 

these factors might contribute to variability in the collision 

efficiency between tracer experiments. Such information 

would also help quantify how to make effective use of the soil 

to protect public health in planned water-reuse programs and to 

design an optimal management scenario that maximizes the 

amount of recycled water applied to the spreading grounds 

while still maintaining favorable attachment conditions for 

virus removal. A management scenario that considers virus 

removal by attachment and (or) inactivation will ensure 

protection to the ground water supply. Finally, this study 

illustrates the importance of conducting field-scale tracer 

experiments at a specific site under actual recharge conditions 

with recycled water using surrogates for human viruses to 

establish setback requirements that ensure adequate pathogen 

removal.

References Cited

American Public Health Association, American Water Works 

Association, Water Pollution Control Federation, 1985, 

Standard methods for the examination of water and 

wastewater, 16th edition: American Public Health 

Association Publication, Washington, D.C., p. 827–944.

Anders, Robert, 1997, Water-quality changes during artificial 

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Anders, Robert, and Schroeder, R.A., 1997, Water-quality 

changes during recharge with recycled water at a research 

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California, in Proceedings of the AWRA 33rd National 

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Resources: Aquifer Storage and Recovery, California 

American Water Resources Association, TPS-97-2. 

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Anders, Robert, and Schroeder, R.A., 2003, Use of waterquality indicators and environmental tracers to determine the 

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30 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

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Appendixes 31

Appendixes
32 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

Appendix A. Water-quality data for selected wells at the research field site in Montebello Forebay, Los Angeles County, California, 1997–2000—Continued

Station name

(Local identifier) Date Time

Depth of 

well 

(ft)

(72008)

Altitude of 

land surface

(ft)

(72000)

Oxygen,

dissolved

(mg/L)

(00300)

pH,

field

(standard 

units)

(00400)

Specific 

conductance,

field

(μS/cm)

(00095)

Water 

temperature

(

οC)

(00010)

Calcium, 

dissolved

(mg/L as Ca)

(00915)

2S/11-W18L27 08/25/1998 1230 49 160.93 0.2 7.4 689 21.6 50.9

(PR8)

2S/11-W18L28 08/25/1998 0945 25 161.04 .5 7.2 895 19.6 67.3

(PR9) 08/28/1998 1130 25 161.04 — 7.2 982 24.7 69.5

08/02/2000 1530 25 161.04 .1 7 959 28.5 59.5

2S/11-W18L29 08/25/1998 1130 60 171.91 0 7.3 632 20.8 45.6

(PR10)

2S/11-W18L30 08/25/1998 1030 36 171.87 .3 7.1 841 19.7 65.1

(PR11) 08/28/1998 1000 36 171.87 7 1,010 26 63.5

08/02/2000 1645 36 171.87 .2 7 936 28.9 58.8

Pond at Pico 08/27/1997 1134 — — — — — — —

08/27/1997 1334 — — — — — — —

08/27/1997 1504 — — — — — — —

08/27/1997 1519 — — — — — — —

08/27/1997 1719 — — — — — — —

08/28/1997 1031 — — — — — — —

08/25/1998 1300 — — 8.6 7.3 1,000 28.8 53.4

08/28/1998 1200 — — 7.3 1,010 29 53.2

08/02/2000 1730 — — 2.1 7.1 990 28.4 56.1

08/04/2000 0300 — — — — — — —

Sewage Effluent 08/25/1998 1800 — — — 7.1 1,080 28.6 55.1

2S/11-W18L31 08/27/1997 1225 7.13 161.88 — — — — —

(WP1) 08/27/1997 1240 7.13 161.88 — — — — —

08/27/1997 1255 7.13 161.88 — — — — —

08/27/1997 1310 7.13 161.88 — — — — —

08/27/1997 1325 7.13 161.88 — — — — —

08/27/1997 1340 7.13 161.88 — — — — —

08/27/1997 1355 7.13 161.88 — — — — —

08/27/1997 1410 7.13 161.88 — — — — —

08/27/1997 1510 7.13 161.88 — — — — —

08/27/1997 1511 7.13 161.88 — — — — —

08/27/1997 1610 7.13 161.88 — — — — —

08/27/1997 1810 7.13 161.88 — — — — —

08/28/1997 0930 7.13 161.88 — — — — —

08/28/1997 1000 7.13 161.88 — — — — —

08/28/1997 1030 7.13 161.88 — — — — —

08/25/1998 1700 7.13 161.88 — 7.1 1,010 28.3 57.4

08/28/1998 1055 7.13 161.88 — 7.2 1,020 29 55.7

Appendix A. Water-quality data for selected wells at the research field site in Montebello Forebay, Los Angeles County, California, 1997–2000

[Number below the compound is the data parameter code, which is a 5-digit number used in the U.S. Geological Survey computerized data system, National 

Water Information System (NWIS), to uniquely identify a specific constituent or property; ft, feet below basin floor or land surface; μS/cm, microsiemens per 

centimeter; οC, degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; <, actual value less than value shown; —, no data; MLS, multilevel 

sampler]
Appendix A 33

2S/11-W18L32 08/28/1997 0930 12.25 161.43 — — — — —

(WP2) 08/28/1997 1000 12.25 161.43 — — — — —

08/28/1997 1030 12.25 161.43 — — — — —

08/25/1998 1100 12.25 161.43 0.2 7.1 992 28.6 56.9

08/28/1998 1115 12.25 161.43 — 7.1 1,030 28.9 57.4

08/04/2000 1030 12.25 161.43 — — — — —

2S/11-W18L42 08/25/1998 1600 60 172.4 — 7.4 641 21.1 47.7

(PR14)

2S/11-W18L43 08/25/1998 1730 35 172.4 .2 7.2 784 21.6 62

(PR15) 08/02/2000 1745 35 172.4 .3 6.7 891 21.5 67.5

Appendix A. Water-quality data for selected wells at the research field site in Montebello Forebay, Los Angeles County, California, 1997–2000—Continued

Station name

(Local identifier) Date Time

Depth of 

well 

(ft)

(72008)

Altitude of 

land surface

(ft)

(72000)

Oxygen,

dissolved

(mg/L)

(00300)

pH,

field

(standard 

units)

(00400)

Specific 

conductance,

field

(μS/cm)

(00095)

Water 

temperature

(

οC)

(00010)

Calcium, 

dissolved

(mg/L as Ca)

(00915)
34 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

Appendix A. Water-quality data for selected wells at the research field site in Montebello Forebay, Los Angeles County, California, 1997–2000—Continued

Station name

(Local identifier) Date Time

Magnesium, 

dissoslved

(mg/L as Mg)

(00925)

Potassium,

dissolved

(mg/L as K)

(90935)

Sodium,

dissolved

(mg/L as Na)

(00930)

Acid

neutralizing

capacity, lab

(mg/L as 

CaCO3)

(90410)

Alkalinity,

fixed 

endpoint,

field,

(mg/L as 

CaCO3)

(39036)

Bromide,

dissolved

(mg/L as Br)

(71870)

Chloride,

dissolved

(mg/L as Cl)

(00940)

2S/11-W18L27 08/25/1998 1230 14.1 4.63 66.9 148 120 0.12 58

(PR8)

2S/11-W18L28 08/25/1998 0945 19.4 6.12 82.9 173 140 .13 93.2

(PR9) 08/28/1998 1130 19.7 7.22 98.8 179 140 2.33 110

08/02/2000 1530 15.7 12 101 — 185 .08 108

2S/11-W18L29 08/25/1998 1130 12.7 4.32 62.7 152 120 .1 46.8

(PR10)

2S/11-W18L30 08/25/1998 1030 18.9 6.01 76.6 167 140 .11 87.6

(PR11) 08/28/1998 1000 17.7 8.4 107 172 140 31.3 113

08/02/2000 1645 16.3 11.1 110 — 182 .08 108

Pond at Pico 08/27/1997 1134 — — — — — 67.2 120

08/27/1997 1334 — — — — — 65.9 122

08/27/1997 1504 — — — — — 78.7 121

08/27/1997 1519 — — — — — 14.9 125

08/27/1997 1719 — — — — — 11.1 130

08/28/1997 1031 — — — — — 2.84 120

08/25/1998 1300 16.5 14.4 110 137 140 .09 113

08/28/1998 1200 16.2 14.9 108 147 140 .25 114

08/02/2000 1730 16.6 12.9 108 — 188 .07 112

08/04/2000 0300

Sewage Effluent 08/25/1998 1800 16.7 10.7 107 121 170 .05 120

2S/11-W18L31 08/27/1997 1225 — — — — — .13 126

(WP1) 08/27/1997 1240 — — — — — .47 124

08/27/1997 1255 — — — — — 4.97 124

08/27/1997 1310 — — — — — 19.1 124

08/27/1997 1325 — — — — — 34.9 123

08/27/1997 1340 — — — — — 49.9 125

08/27/1997 1355 — — — — — 69.1 126

08/27/1997 1410 — — — — — 22.5 121

08/27/1997 1510 — — — — — 115 125

08/27/1997 1511 — — — — — 115 123

08/27/1997 1610 — — — — — 108 120

08/27/1997 1810 — — — — — 85.9 123

08/28/1997 0930 — — — — — 15.9 120

08/28/1997 1000 — — — — — 5.51 122

08/28/1997 1030 — — — — — 14.8 127

08/25/1998 1700 16 12.4 108 147 140 .11 116

08/28/1998 1055 16.1 20.2 112 162 150 7.79 115
Appendix A 35

2S/11-W18L32 08/28/1997 0930 — — — — — 5.33 119

(WP2) 08/28/1997 1000 — — — — — 15.5 125

08/28/1997 1030 — — — — — 4.72 130

08/25/1998 1100 15.5 12.2 102 150 140 .09 109

08/28/1998 1115 16.7 13.3 113 154 150 10.1 115

08/04/2000 1030

2S/11-W18L42 08/25/1998 1600 13.4 4.27 61.7 155 120 .09 48

(PR14)

2S/11-W18L43 08/25/1998 1730 18.9 6.11 67 162 130 .14 68.6

(PR15) 08/02/2000 1745 18.8 6.85 87.2 — 143 .17 95.2

Appendix A. Water-quality data for selected wells at the research field site in Montebello Forebay, Los Angeles County, California, 1997–2000—Continued

Station name

(Local identifier) Date Time

Magnesium, 

dissoslved

(mg/L as Mg)

(00925)

Potassium,

dissolved

(mg/L as K)

(90935)

Sodium,

dissolved

(mg/L as Na)

(00930)

Acid

neutralizing

capacity, lab

(mg/L as 

CaCO3)

(90410)

Alkalinity,

fixed 

endpoint,

field,

(mg/L as 

CaCO3)

(39036)

Bromide,

dissolved

(mg/L as Br)

(71870)

Chloride,

dissolved

(mg/L as Cl)

(00940)
36 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

Appendix A. Water-quality data for selected wells at the research field site in Montebello Forebay, Los Angeles County, California, 1997–2000—Continued

Station name

(Local identifier) Date Time

Fluoride,

dissolved

(mg/L as F)

(00950)

Iodine,

dissolved

(mg/L as I)

(71865)

Silica,

dissolved

(mg/L as 

SiO2)

(00955)

Sulfate,

dissolved

(mg/L as 

SO4)

(00945)

Nitrogen,

ammonia 

plus organic 

nitrogran,

dissolved

(mg/L as N)

(00623)

Nitrogen,

ammonia, 

dissolved

(mg/L as N)

(00608)

Nitrogen,

nitrite plus 

nitrate, 

dissolved

(mg/L as N)

(00631)

2S/11-W18L27 08/25/1998 1230 0.6 0.019 16.9 99 <0.1 0.03 0.91

(PR8)

2S/11-W18L28 08/25/1998 0945 .6 .024 16.9 115 .48 .03 2.22

(PR9) 08/28/1998 1130 .7 .023 20.4 113 .67 .18 4.84

08/02/2000 1530 .7 — 20.1 105 3 2.39 3.17

2S/11-W18L29 08/25/1998 1130 .7 .016 16.7 86.9 .12 .03 1.06

(PR10)

2S/11-W18L30 08/25/1998 1030 .5 .022 17.7 107 .34 .12 1.69

(PR11) 08/28/1998 1000 .6 .016 21.7 112 .65 .22 3.46

08/02/2000 1645 .6 — 20.3 105 1.3 .78 2.12

Pond at Pico 08/27/1997 1134 — — — — — — —

08/27/1997 1334 — — — — — — —

08/27/1997 1504 — — — — — — —

08/27/1997 1519 — — — — — — —

08/27/1997 1719 — — — — — — —

08/28/1997 1031 — — — — — — —

08/25/1998 1300 .6 .02 19.4 114 6.7 5.59 6.4

08/28/1998 1200 .6 .017 19.8 108 6.9 5.58 5.71

08/02/2000 1730 .6 — 21.9 105 8.8 <.02 <.05

08/04/2000 0300 — — — — — — —

Sewage Effluent 08/25/1998 1800 .6 .077 20.5 105 16 15.4 4.62

2S/11-W18L31 08/27/1997 1225 — — — — — — —

(WP1) 08/27/1997 1240 — — — — — — —

08/27/1997 1255 — — — — — — —

08/27/1997 1310 — — — — — — —

08/27/1997 1325 — — — — — — —

08/27/1997 1340 — — — — — — —

08/27/1997 1355 — — — — — — —

08/27/1997 1410 — — — — — — —

08/27/1997 1510 — — — — — — —

08/27/1997 1511 — — — — — — —

08/27/1997 1610 — — — — — — —

08/27/1997 1810 — — — — — — —

08/28/1997 0930 — — — — — — —

08/28/1997 1000 — — — — — — —

08/28/1997 1030 — — — — — — —

08/25/1998 1700 .5 .012 19.2 114 5.2 4.59 5.57

08/28/1998 1055 .6 0.01 18.3 111 5.2 4.45 2.74
Appendix A 37

2S/11-W18L32 08/28/1997 0930 — — — — — — —

(WP2) 08/28/1997 1000 — — — — — — —

08/28/1997 1030 — — — — — — —

08/25/1998 1100 0.6 0.021 19.8 113 5 4.38 5.3

08/28/1998 1115 .6 .01 18.4 112 5.6 5.22 3.39

08/04/2000 1030 — — — — — — —

2S/11-W18L42 08/25/1998 1600 .6 .017 16.9 87.7 <.1 .03 .43

(PR14)

2S/11-W18L43 08/25/1998 1730 .5 .031 17.8 121 <.1 .04 .09

(PR15) 08/02/2000 1745 .3 20.2 149 .13 <.02 .23

Appendix A. Water-quality data for selected wells at the research field site in Montebello Forebay, Los Angeles County, California, 1997–2000—Continued

Station name

(Local identifier) Date Time

Fluoride,

dissolved

(mg/L as F)

(00950)

Iodine,

dissolved

(mg/L as I)

(71865)

Silica,

dissolved

(mg/L as 

SiO2)

(00955)

Sulfate,

dissolved

(mg/L as 

SO4)

(00945)

Nitrogen,

ammonia 

plus organic 

nitrogran,

dissolved

(mg/L as N)

(00623)

Nitrogen,

ammonia, 

dissolved

(mg/L as N)

(00608)

Nitrogen,

nitrite plus 

nitrate, 

dissolved

(mg/L as N)

(00631)
38 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

Appendix A. Water-quality data for selected wells at the research field site in Montebello Forebay, Los Angeles County, California, 1997–2000—Continued

Station name

(Local identifier) Date Time

Nitrogen,

nitrite,

dissolved

(mg/L as N)

(00613)

Phosphorus,

dissolved

(mg/L as P)

(00666)

Total organic 

carbon

(mg/L)

(00681)

Organic 

carbon,

dissolved

(mg/L)

(00680

Boron,

dissolved

(mg/L as B)

(01020)

Iron,

dissolved

(mg/L as Fe)

(01046)

Manganese,

dissolved

(mg/L as Mn)

(01056)

2S/11-W18L27 08/25/1998 1230 0.03 1.7 187 <10 934

(PR8)

2S/11-W18L28 08/25/1998 0945 .821 — 3.4 — 251 <10 1,420

(PR9) 08/28/1998 1130 2.25 — 4.5 — 364 <10 1,370

08/02/2000 1530 .378 1.46 — 4.5 438 18 4.5

2S/11-W18L29 08/25/1998 1130 .041 — 1.5 — 168 <10 920

(PR10)

2S/11-W18L30 08/25/1998 1030 .339 — 3.2 — 241 <10 1,010

(PR11) 08/28/1998 1000 1.25 — 4.8 — 373 <10 <4

08/02/2000 1645 .018 1.4 — 4.3 454 15 2.3

Pond at Pico 08/27/1997 1134 — — — — — — —

08/27/1997 1334 — — — — — — —

08/27/1997 1504 — — — — — — —

08/27/1997 1519 — — — — — — —

08/27/1997 1719 — — — — — — —

08/28/1997 1031 — — — — — — —

08/25/1998 1300 3.04 — 9 — 399 33 13.4

08/28/1998 1200 2.73 — 8.8 — 372 29 4.3

08/02/2000 1730 <.01 1.59 — 9.1 454 29 15.9

08/04/2000 0300 — — — 9.5 — — —

Sewage Effluent 08/25/1998 1800 2.43 — 8.8 — 362 45 13.4

2S/11-W18L31 08/27/1997 1225 — — — — — — —

(WP1) 08/27/1997 1240 — — — — — — —

08/27/1997 1255 — — — — — — —

08/27/1997 1310 — — — — — — —

08/27/1997 1325 — — — — — — —

08/27/1997 1340 — — — — — — —

08/27/1997 1355 — — — — — — —

08/27/1997 1410 — — — — — — —

08/27/1997 1510 — — — — — — —

08/27/1997 1511 — — — — — — —

08/27/1997 1610 — — — — — — —

08/27/1997 1810 — — — — — — —

08/28/1997 0930 — — — — — — —

08/28/1997 1000 — — — — — — —

08/28/1997 1030 — — — — — — —

08/25/1998 1700 2.57 — 6.6 — 400 284 55.7

08/28/1998 1055 1.09 — 5.9 — 351 129 52.4

2S/11-W18L32 08/28/1997 0930 — — — — — — —

(WP2) 08/28/1997 1000 — — — — — — —
Appendix A 39

08/28/1997 1030 — — — — — — —

08/25/1998 1100 2.6 — 5.8 — 369 24 21.3

08/28/1998 1115 1.98 — 5.8 — 336 15 29.3

08/04/2000 1030 — — — 4.6 — — —

2S/11-W18L42 08/25/1998 1600 .027 — 1.6 — 181 <10 828

(PR14)

2S/11-W18L43 08/25/1998 1730 <.01 — 2 — 194 <10 515

(PR15) 08/02/2000 1745 <.01 0.68 — 1.5 264 <10 2.3

Appendix A. Water-quality data for selected wells at the research field site in Montebello Forebay, Los Angeles County, California, 1997–2000—Continued

Station name

(Local identifier) Date Time

Nitrogen,

nitrite,

dissolved

(mg/L as N)

(00613)

Phosphorus,

dissolved

(mg/L as P)

(00666)

Total organic 

carbon

(mg/L)

(00681)

Organic 

carbon,

dissolved

(mg/L)

(00680

Boron,

dissolved

(mg/L as B)

(01020)

Iron,

dissolved

(mg/L as Fe)

(01046)

Manganese,

dissolved

(mg/L as Mn)

(01056)
40 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

Appendix B. Measured bacteriophage for water samples collected during the 1997 tracer experiment from a research field site located in Los Angeles County, 

California—Continued

Date and time collected

Elapsed

time

(hr)

PRD1

(pfu/mL) Date and time collected

Elapsed

time

(hr)

PRD1

(pfu/mL)

PRD1

(pfu/mL)

PR12 WP1 (1.5 m) WP2 (3.0 m)

08/27/1997 1104 0.23 1.9 × 104 08/27/1997 1140 0.83 <1 —

08/27/1997 1119 0.48 2.8 × 104 08/27/1997 1155 1.08 <1 —

08/27/1997 1134 0.73 2.1 × 104 08/27/1997 1201 1.18 <1 —

08/27/1997 1149 0.98 2.4 × 104 08/27/1997 1225 1.58 <1 —

08/27/1997 1204 1.23 2.3 × 104 08/27/1997 1240 1.83 1 —

08/27/1997 1219 1.48 2.1 × 104 08/27/1997 1255 2.08 15 —

08/27/1997 1234 1.73 2.6 × 104 08/27/1997 1310 2.33 50 —

08/27/1997 1249 1.98 1.7 × 104 08/27/1997 1325 2.58 88 —

08/27/1997 1304 2.23 2.1 × 104 08/27/1997 1340 2.83 100 —

08/27/1997 1319 2.48 2.1 × 104 08/27/1997 1355 3.08 130 —

08/27/1997 1334 2.73 2.3 × 104 08/27/1997 1410 3.33 85 —

08/27/1997 1349 2.98 2.7 × 104 08/27/1997 1425 3.58 120 —

08/27/1997 1404 3.23 2.7 × 104 08/27/1997 1440 3.83 110 —

08/27/1997 1419 3.48 2.1 × 104 08/27/1997 1455 4.08 93 —

08/27/1997 1434 3.73 1.9 × 104 08/27/1997 1510 4.33 87 —

08/27/1997 1449 3.98 2.2 × 104 08/27/1997 1525 4.58 66 —

08/27/1997 1504 4.23 1.7 × 104 08/27/1997 1540 4.83 140 —

08/27/1997 1519 4.48 3.8 × 102 08/27/1997 1555 5.08 62 —

08/27/1997 1534 4.73 4.0 × 102 08/27/1997 1610 5.33 120 —

08/27/1997 1549 4.98 2.0 × 102 08/27/1997 1625 5.58 45 —

08/27/1997 1604 5.23 9.9 × 101 08/27/1997 1640 5.83 67 —

08/27/1997 1619 5.48 1.6 × 102 08/27/1997 1655 6.08 57 —

08/27/1997 1634 5.73 1.6 × 102 08/27/1997 1710 6.33 60 —

08/27/1997 1649 5.98 1.6 × 102 08/27/1997 1725 6.58 58 <1

08/27/1997 1704 6.23 1.1 × 102 08/27/1997 1740 6.83 58 <1

08/27/1997 1719 6.48 9.0 × 101 08/27/1997 1755 7.08 46 <1

08/27/1997 1734 6.73 1.3 × 102 08/27/1997 1810 7.33 46 <1

08/27/1997 1749 6.98 1.1 × 102 08/28/1997 0900 22.17 6 <1

08/27/1997 1804 7.23 1.2 × 102 08/28/1997 0930 22.67 3 <1

08/28/1997 1030 23.67 4.2 × 101 08/28/1997 1000 23.17 7 <1

08/28/1997 1330 26.67 2.4 × 101 08/28/1997 1030 23.67 4 <1

08/28/1997 1100 24.17 6 <1

P2 08/28/1997 1130 24.67 3 <1

8/27/1997 11:02 0.20 2.6 × 102 08/28/1997 1200 25.17 6 <1

8/27/1997 11:17 0.45 2.4 × 103 08/28/1997 1230 25.67 5 <1

8/27/1997 11:32 0.70 2.5 × 103 08/28/1997 1300 26.17 3 <1

08/28/1997 1330 26.67 1 <1

P3 08/28/1997 1400 27.17 6 <1

8/27/1997 11:47 0.95 1.4 × 103 08/28/1997 1430 27.67 2 <1

8/27/1997 12:02 1.20 1.5 × 104 08/28/1997 1500 28.17 6 <1

Appendix B. Measured bacteriophage concentrations for water samples collected during the 1997 tracer experiment from a research field site located in Los 

Angeles County, California

[hr, hour; pfu/mL, plaque-forming units per millileter; <, actual value less than value shown; — no data; P2–P4, samples collected along perimeter of test basin]
Appendix B 41

08/27/1997 1217 1.45 7.2 × 104 08/28/1997 1530 28.67 2 <1

08/27/1997 1104 0.23 7.2 × 104 08/28/1997 1600 29.17 2 <1

08/27/1997 1119 0.48 1.9 × 104 08/28/1997 1700 30.17 4 <1

08/27/1997 1134 0.73 1.8 × 104 08/29/1997 1000 47.17 <1 <1

P4

08/27/1997 1149 0.98 2.8 × 104

08/27/1997 1204 1.23 2.0 × 104

08/27/1997 1219 1.48 1.6 × 104

08/27/1997 1108 0.30 3.0 × 100

08/27/1997 1123 0.55 4.0 × 100

08/27/1997 1138 0.80 9.0 × 100

08/27/1997 1157 1.12 7.0 × 100

08/27/1997 1208 1.30 1.6 × 101

08/27/1997 1223 1.55 1.1 × 101

Appendix B. Measured bacteriophage for water samples collected during the 1997 tracer experiment from a research field site located in Los Angeles County, 

California—Continued

Date and time collected

Elapsed

time

(hr)

PRD1

(pfu/mL) Date and time collected

Elapsed

time

(hr)

PRD1

(pfu/mL)

PRD1

(pfu/mL)
42 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

Appendix C. Measured bromide concentrations for water samples collected during the 1998 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

Bromide

(mg/L)

PR12 08/26/1998 1005 0.08 266.45

08/26/1998 1030 .50 218.65

08/26/1998 1100 1.00 116.40

08/26/1998 1230 2.50 105.40

08/26/1998 1405 4.08 101.25

08/26/1998 1500 5.00 99.97

08/26/1998 1600 6.00 99.78

08/26/1998 1700 7.00 100.81

08/26/1998 1800 8.00 99.33

08/26/1998 1900 9.00 97.19

08/26/1998 2000 10.00 97.04

08/26/1998 2100 11.00 97.94

08/26/1998 2200 12.00 98.42

08/26/1998 2300 13.00 97.74

08/26/1998 0000 14.00 99.88

08/27/1998 0200 16.00 98.70

08/27/1998 0600 20.00 97.92

08/27/1998 0900 23.00 98.26

08/27/1998 1000 24.00 74.50

08/27/1998 1030 24.50 69.87

08/27/1998 1100 25.00 61.28

08/27/1998 1130 25.50 57.92

08/27/1998 1200 26.00 53.82

08/27/1998 1245 26.75 48.03

08/27/1998 1315 27.25 40.75

08/27/1998 1345 27.75 37.49

08/27/1998 1500 29.00 29.95

08/27/1998 1600 30.00 29.31

08/27/1998 1700 31.00 22.69

08/27/1998 1800 32.00 20.91

08/28/1998 1200 50.00 2.88

08/29/1998 0820 70.33 .40

08/30/1998 0950 95.83 .40

08/31/1998 1025 120.42 .40

09/01/1998 0840 142.67 .40

09/02/1998 0846 166.77 .40

09/03/1998 0847 190.78 .40

09/04/1998 0905 215.08 .40

P1 08/26/1998 1010 .17 —

08/26/1998 1105 1.08 145.57

08/26/1998 1405 4.08 103.11

08/26/1998 1705 7.08 113.90

Appendix C. Measured bromide concentrations for water samples collected during the 1998 tracer experiment from a research field site located in Los 

Angeles County, California

[hr, hour; mg/L, milligrams per liter; —, no data]
Appendix C 43

08/27/1998 0700 21.00 98.21

P2 08/26/1998 1010 .17 133.07

08/26/1998 1105 1.08 113.84

08/26/1998 1405 4.08 97.93

08/26/1998 1705 7.08 101.30

08/27/1998 0700 21.00 98.51

P3 08/26/1998 1010 .17 116.89

08/26/1998 1105 1.08 109.53

08/26/1998 1405 4.08 102.50

08/26/1998 1705 7.08 106.52

08/27/1998 0700 21.00 98.94

P4 08/26/1998 1010 .17 55.33

08/26/1998 1105 1.08 104.94

08/26/1998 1405 4.08 97.95

08/26/1998 1705 7.08 99.43

08/27/1998 0700 21.00 99.96

WP1 08/26/1998 1030 0.50 .20

08/26/1998 1100 1.00 .20

08/26/1998 1130 1.50 .20

08/26/1998 1230 2.50 .20

08/26/1998 1305 3.08 .20

08/26/1998 1330 3.50 .20

08/26/1998 1335 3.58 .57

08/26/1998 1340 3.67 1.31

08/26/1998 1350 3.83 3.36

08/26/1998 1355 3.92 4.98

08/26/1998 1405 4.08 8.30

08/26/1998 1410 4.17 12.19

08/26/1998 1420 4.33 18.04

08/26/1998 1425 4.42 21.87

08/26/1998 1430 4.50 24.80

08/26/1998 1435 4.58 32.13

08/26/1998 1440 4.67 28.61

08/26/1998 1445 4.75 37.13

08/26/1998 1450 4.83 44.98

08/26/1998 1455 4.92 48.67

08/26/1998 1500 5.00 53.41

08/26/1998 1505 5.08 64.49

08/26/1998 1510 5.17 63.45

08/26/1998 1515 5.25 67.45

08/26/1998 1520 5.33 73.64

08/26/1998 1530 5.50 78.30

08/26/1998 1535 5.58 80.19

08/26/1998 1540 5.67 83.65

08/26/1998 1545 5.75 89.86

Appendix C. Measured bromide concentrations for water samples collected during the 1998 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

Bromide

(mg/L)
44 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

08/26/1998 1550 5.83 95.50

08/26/1998 1600 6.00 101.40

08/26/1998 1615 6.25 109.97

08/26/1998 1630 6.50 119.80

08/26/1998 1645 6.75 124.30

08/26/1998 1700 7.00 130.26

08/26/1998 1715 7.25 132.37

08/26/1998 1730 7.50 131.40

08/26/1998 1800 8.00 125.82

08/26/1998 1900 9.00 111.68

08/26/1998 2000 10.00 105.06

08/26/1998 2100 11.00 102.30

08/26/1998 2200 12.00 100.11

08/26/1998 2300 13.00 98.50

08/27/1998 0000 14.00 99.02

08/27/1998 0200 16.00 97.89

08/27/1998 0600 20.00 91.31

08/27/1998 0700 21.00 93.5

08/27/1998 1245 26.75 98.09

08/27/1998 1500 29.00 98.70

08/27/1998 1600 30.00 101.54

08/27/1998 1700 31.00 91.31

08/27/1998 1800 32.00 85.69

08/28/1998 1055 48.92 7.80

08/28/1998 1205 50.08 .40

08/29/1998 0810 70.17 .70

08/30/1998 0935 95.58 .40

08/31/1998 1012 120.20 .40

09/01/1998 0825 142.42 .40

09/02/1998 0930 167.50 .40

09/03/1998 0842 190.70 .40

09/04/1998 0855 214.92 .40

WP2 08/26/1998 1405 4.08 .20

08/26/1998 1500 5.00 .20

08/26/1998 1600 6.00 .20

08/26/1998 1700 7.00 .20

08/26/1998 1800 8.00 4.31

08/26/1998 1820 8.33 17.15

08/26/1998 1830 8.50 22.79

08/26/1998 1840 8.67 33.22

08/26/1998 1850 8.83 42.33

08/26/1998 1900 9.00 57.48

08/26/1998 1915 9.25 70.37

08/26/1998 1930 9.50 87.42

Appendix C. Measured bromide concentrations for water samples collected during the 1998 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

Bromide

(mg/L)
Appendix C 45

08/26/1998 1945 9.75 100.58

08/26/1998 2000 10.00 114.28

08/26/1998 2015 10.25 107.70

08/26/1998 2030 10.50 125.96

08/26/1998 2100 11.00 138.94

08/26/1998 2115 11.25 134.75

08/26/1998 2200 12.00 135.57

08/26/1998 2300 13.00 122.93

08/26/1998 0000 14.00 112.37

08/27/1998 0200 16.00 104.45

08/27/1998 0600 20.00 97.41

08/27/1998 0700 21.00 101.24

08/27/1998 1000 24.00 97.88

08/27/1998 1315 27.25 96.80

08/27/1998 1630 30.50 97.10

08/27/1998 1800 32.00 91.79

08/28/1998 1115 49.25 8.71

08/29/1998 0815 70.25 1.26

08/30/1998 0940 95.67 .40

08/31/1998 1013 120.22 .40

09/01/1998 0825 142.42 .40

09/02/1998 0840 166.67 .40

09/03/1998 0856 190.93 .40

09/04/1998 0915 215.25 .40

WP7 08/26/1998 2200 12.00 .2

08/27/1998 0200 16.00 4.73

08/27/1998 0600 20.00 5.46

08/27/1998 1030 24.50 .2

08/27/1998 1115 25.25 .2

08/27/1998 1245 26.75 .2

08/27/1998 1500 29.00 .2

08/27/1998 1600 30.00 .2

08/27/1998 1700 31.00 .2

08/27/1998 1800 32.00 4.18

08/28/1998 1030 48.50 39.81

08/29/1998 0830 70.50 68.40

08/30/1998 0925 95.42 7.37

08/31/1998 1006 120.10 .98

09/01/1998 0830 142.50 .2

09/02/1998 0955 167.92 .26

09/03/1998 0835 190.58 .2

09/04/1998 0900 215.00 .2

PR9 08/26/1998 1500 5.00 .2

08/26/1998 1600 6.00 .2

08/26/1998 1700 7.00 .2

08/26/1998 1800 8.00 0.2

Appendix C. Measured bromide concentrations for water samples collected during the 1998 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

Bromide

(mg/L)
46 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

08/26/1998 1900 9.00 .2

08/26/1998 2000 10.00 .2

08/26/1998 2100 11.00 .2

08/27/1998 0200 16.00 .2

08/27/1998 0415 18.25 .2

08/27/1998 0600 20.00 .2

08/27/1998 0700 21.00 .2

08/27/1998 0900 23.00 .2

08/27/1998 1000 24.00 .2

08/27/1998 1030 24.50 .2

08/27/1998 1100 25.00 .2

08/27/1998 1130 25.50 .2

08/27/1998 1245 26.75 .2

08/27/1998 1315 27.25 .2

08/27/1998 1500 29.00 .2

08/27/1998 1600 30.00 .2

08/27/1998 1700 31.00 .2

08/27/1998 1800 32.00 .2

08/28/1998 1130 49.50 2.73

08/29/1998 855 70.92 32.59

08/30/1998 1000 96.00 28.04

08/31/1998 1030 120.50 5.98

09/01/1998 0855 142.92 .19

09/02/1998 0925 167.42 .2

09/03/1998 0856 190.93 .2

09/04/1998 0925 215.42 .2

PR11 08/27/1998 0700 21.00 <.3

08/27/1998 1100 25.00 .5

08/27/1998 1115 25.25 .5

08/27/1998 1515 29.25 .6

08/27/1998 1630 30.50 .5

08/27/1998 1800 32.00 1

08/28/1998 0925 47.42 4.2

08/28/1998 1000 48.00 14

08/29/1998 0800 70.00 31

08/30/1998 0855 94.92 55

08/31/1998 0935 119.58 64

09/01/1998 0811 142.18 56

09/02/1998 0821 166.35 43

09/03/1998 0814 190.23 17

09/04/1998 0830 214.50 3.7

GP1 08/26/1998 1320 3.33 108.90

08/26/1998 1605 6.08 98.18

08/26/1998 1915 9.25 95.50

Appendix C. Measured bromide concentrations for water samples collected during the 1998 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

Bromide

(mg/L)
Appendix C 47

08/27/1998 0720 21.33 97.59

GP2 08/26/1998 1315 3.25 124.1

08/26/1998 1610 6.17 98.40

08/26/1998 1910 9.17 96.11

08/27/1998 0735 21.58 97.9

GP3 08/26/1998 1310 3.17 179.00

08/26/1998 1615 6.25 102.00

08/26/1998 1905 9.08 96.30

GP3 08/26/1998 1310 3.17 179.00

Appendix C. Measured bromide concentrations for water samples collected during the 1998 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

Bromide

(mg/L)
48 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

Appendix D. Measured bacteriophage concentrations for water samples collected during the 1998 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

MS2 PRD1

(pfu/mL)

PR12 08/26/1998 1005 0.08 6.5 × 105 6.9 × 104

08/26/1998 1105 1.08 3.3 × 105 3.0 × 104

08/26/1998 1205 2.08 2.4 × 105 2.0 × 104

08/26/1998 1305 3.08 2.2 × 105 3.0 × 104

08/26/1998 1405 4.08 2.9 × 105 3.1 × 104

08/26/1998 1500 5.00 2.5 × 105 3.1 × 104

08/26/1998 1605 6.08 1.9 × 105 1.5 × 104

08/26/1998 1705 7.08 1.5 × 105 1.2 × 104

08/27/1998 0105 15.08 6.6 × 104 6.4 × 103

08/27/1998 0700 21.00 5.4 × 104 9.0 × 103

08/27/1998 0900 23.00 4.9 × 104 7.4 × 103

08/27/1998 1000 24.00 2.0 × 104 2.4 × 103

08/27/1998 1100 25.00 1.6 × 104 1.9 × 103

08/27/1998 1200 26.00 1.4 × 104 1.1 × 103

08/27/1998 1505 29.08 1.7 × 103 6.5 × 100

08/27/1998 1705 31.08 7.2 × 102 1.5 × 100

08/28/1998 0937 47.62 5.1 × 101 .0 × 100

08/29/1998 0820 70.33 5.5 × 100 1.0 × 100

08/30/1998 0950 95.83 5.0 × 10−1 5.0 × 10−1

08/31/1998 1025 120.42 2.0 × 10−2 2.0 × 102

09/01/1998 0840 142.67 3.5 × 100 2.0 × 10−2

09/02/1998 0846 166.77 2.8 × 100 2.0 × 10−2

09/03/1998 0847 190.78 2.8 × 100 2.0 × 10−2

09/04/1998 0905 215.08 8.0 × 10−1 2.0 × 10−2

P1 08/26/1998 1010 .17 6.5 × 105 6.9 × 104

08/26/1998 1105 1.08 3.3 × 105 3.0 × 104

08/26/1998 1405 4.08 2.9 × 105 3.1 × 104

08/26/1998 1705 7.08 1.5 × 105 1.2 × 104

08/27/1998 0700 21.00 5.4 × 104 9.0 × 103

P2 08/26/1998 1010 .17 2.2 × 104 2.1 × 103

08/26/1998 1105 1.08 4.1 × 105 3.8 × 104

08/26/1998 1405 4.08 2.7 × 105 2.7 × 104

08/26/1998 1705 7.08 6.3 × 104 6.8 × 103

08/27/1998 0700 21.00 3.5 × 104 8.1 × 103

P3 08/26/1998 1010 .17 3.5 × 105 3.0 × 104

08/26/1998 1105 1.08 3.5 × 105 4.2 × 104

08/26/1998 1405 4.08 1.2 × 105 2.3 × 104

08/26/1998 1705 7.08 9.4 × 104 1.5 × 104

Appendix D. Measured bacteriophage concentrations for water samples collected during the 1998 tracer experiment from a research field site located in Los 

Angeles County, California

[hr, hour; pfu/L, plaque forming units per milliliter]
Appendix D 49

08/27/1998 0700 21.00 5.4 × 104 8.9 × 103

P4 08/26/1998 1010 .17 5.4 × 104 8.9 × 103

08/26/1998 1105 1.08 5.9 × 105 4.2 × 104

08/26/1998 1405 4.08 1.1 × 105 2.0 × 104

08/26/1998 1705 7.08 1.2 × 105 8.9 × 103

08/27/1998 0700 21.00 6.7 × 104 1.0 × 104

WP1 08/26/1998 1205 2.08 5.0 × 10−1 .0 × 100

08/26/1998 1305 3.08 5.7 × 101 5.0 × 10−1

08/26/1998 1405 4.08 5.5 × 103 1.2 × 102

08/26/1998 1500 5.00 1.8 × 104 2.0 × 102

08/26/1998 1605 6.08 3.2 × 104 3.2 × 102

08/26/1998 1705 7.08 6.0 × 104 2.6 × 102

08/26/1998 1800 8.00 3.7 × 104 2.3 × 102

08/26/1998 1900 9.00 3.9 × 104 1.8 × 102

08/26/1998 2005 10.08 2.4 × 104 1.5 × 102

08/26/1998 2105 11.08 2.1 × 104 1.1 × 102

08/26/1998 2305 13.08 1.2 × 104 5.1 × 101

08/27/1998 0105 15.08 9.3 × 103 2.0 × 101

08/27/1998 0300 17.00 9.5 × 102 1.8 × 101

08/27/1998 0500 19.00 1.5 × 102 1.0 × 101

08/27/1998 0700 21.00 1.0 × 103 5.0 × 100

08/27/1998 0900 23.00 1.3 × 103 2.5 × 100

08/27/1998 1100 25.00 8.6 × 102 2.0 × 100

08/27/1998 1305 27.08 6.2 × 102 1.0 × 100

08/27/1998 1505 29.08 4.0 × 102 3.5 × 100

08/27/1998 1705 31.08 6.9 × 102 1.0 × 100

08/27/1998 1805 32.08 4.5 × 102 5.0 × 10−1

08/28/1998 0955 47.92 2.4 × 100 4.0 × 10−2

08/29/1998 0810 70.17 4.7 × 101 1.5 × 100

08/30/1998 0935 95.58 1.6 × 101 6.0 × 10−2

08/31/1998 10:12 120.20 3.0 × 100 2.0 × 10−2

09/01/1998 0825 142.42 2.4 × 100 2.0 × 10−2

09/02/1998 0930 167.50 5.0 × 100 2.0 × 10−2

09/03/1998 0842 190.70 1.3 × 100 2.0 × 10−2

09/04/1998 0855 214.92 2.3 × 10−1 2.0 × 10−2

WP2 08/26/1998 1405 4.08 2.0 × 10−2 2.0 × 10−2

08/26/1998 1500 5.00 4.0 × 10−2 2.0 × 10−2

08/26/1998 1805 8.08 1.1 × 103 5.0 × 101

08/26/1998 1902 9.03 1.0 × 104 1.2 × 102

08/26/1998 2005 10.08 2.0 × 104 2.0 × 102

08/26/1998 2105 11.08 2.3 × 104 2.2 × 102

08/26/1998 2205 12.08 2.5 × 104 2.4 × 102

08/26/1998 2305 13.08 2.6 × 104 3.4 × 102

08/27/1998 0005 14.08 3.4 × 104 4.2 × 102

08/27/1998 0105 15.08 2.5 × 104 5.6 × 102

Appendix D. Measured bacteriophage concentrations for water samples collected during the 1998 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

MS2 PRD1

(pfu/mL)
50 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

08/27/1998 0203 16.05 4.0 × 102 4.3 × 102

08/27/1998 0300 17.00 2.3 × 103 2.7 × 102

08/27/1998 0400 18.00 2.5 × 103 1.2 × 102

08/27/1998 0500 19.00 6.6 × 102 8.0 × 101

08/27/1998 0600 20.00 4.6 × 102 7.5 × 101

08/27/1998 0700 21.00 1.6 × 101 2.0 × 10−2

08/27/1998 0900 23.00 1.2 × 103 1.3 × 100

08/27/1998 1100 25.00 8.0 × 102 2.8 × 100

08/27/1998 1305 27.08 2.8 × 103 3.0 × 101

08/27/1998 1505 29.08 2.4 × 103 0.0 × 100

08/27/1998 1705 31.08 1.6 × 101 1.4 × 100

08/27/1998 1805 32.08 1.6 × 101 7.0 × 10−1

08/28/1998 0955 47.92 2.4 × 100 1.1 × 10−1

08/29/1998 0815 70.25 2.4 × 100 9.0 × 10−2

08/30/1998 0940 95.67 2.4 × 100 2.0 × 10−2

08/31/1998 1013 120.22 8.0 × 10−1 2.0 × 10−2

09/01/1998 0825 142.42 2.4 × 100 2.0 × 10−2

09/02/1998 0840 166.67 5.0 × 100 2.0 × 10−2

09/03/1998 0856 190.93 8.0 × 10−1 2.0 × 10−2

09/04/1998 0915 215.25 1.1 × 100 2.0 × 10−2

WP7 08/27/1998 0700 21.00 >1/1000 <1/1000

08/27/1998 1100 25.00 <1/1000 <1/1000

08/27/1998 1505 29.08 <1/1000 <1/1000

08/27/1998 1805 32.08 >1/1000 <1/1000

08/28/1998 1000 48.00 >1/1000 <1/1000

08/29/1998 0830 70.50 >1/1000 >1/1000

08/30/1998 0925 95.42 >1/1000 <1/1000

08/31/1998 1006 120.10 >1/1000 <1/1000

09/01/1998 0830 142.50 >1/1000 <1/

09/02/1998 0955 167.92 >1/1000 >1/1000

09/03/1998 0835 190.58 >1/1000 >1/1000

09/04/1998 0900 215.00 >1/1000 >1/1000

PR9 08/26/1998 1900 9.00 <1/100 <1/1000

08/26/1998 2105 11.08 <1/100 <1/1000

08/26/1998 2305 13.08 >1/100 <1/1000

08/27/1998 0105 15.08 <1/100 <1/1000

08/27/1998 0400 18.00 <1/100 <1/1000

08/27/1998 0700 21.00 <1/100 <1/1000

08/27/1998 1100 25.00 <1/100 <1/1000

08/27/1998 1505 29.08 <1/100 <1/1000

08/27/1998 1805 32.08 <1/100 <1/1000

08/28/1998 1055 48.92 >1/100 <1/1000

08/29/1998 0855 70.92 >1/100 <1/1000

08/30/1998 1000 96.00 >1/100 <1/1000

Appendix D. Measured bacteriophage concentrations for water samples collected during the 1998 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

MS2 PRD1

(pfu/mL)
Appendix D 51

08/31/1998 1030 120.50 >1/100 <1/1000

09/01/1998 0855 142.92 >1/100 <1/

09/02/1998 0925 167.42 >1/100 <1/1000

09/03/1998 0856 190.93 >1/100 <1/1000

09/04/1998 0925 215.42 >1/100 <1/1000

PR11 08/27/1998 0700 21.00 >1/1000 <1/1000

08/27/1998 1100 25.00 >1/1000 <1/1000

08/27/1998 1505 29.08 <1/1000 <1/1000

08/27/1998 1805 32.08 <1/1000 <1/1000

08/28/1998 0925 47.42 >1/1000 <1/1000

08/29/1998 0800 70.00 >1/1000 >1/1000

08/30/1998 0855 94.92 >1/1000 <1/1000

08/31/1998 0935 119.58 >1/1000 <1/1000

09/01/1998 0811 142.18 >1/1000 <1/

09/02/1998 0821 166.35 >1/1000 <1/1000

09/03/1998 0814 190.23 >1/1000 <1/1000

09/04/1998 0830 214.50 >1/1000 <1/1000

GP1 08/26/1998 1320 3.33 1.4 × 105 1.1 × 104

08/26/1998 1605 6.08 9.0 × 104 1.1 × 104

08/26/1998 1915 9.25 1.1 × 105 8.0 × 103

08/27/1998 0720 21.33 1.9 × 104 3.4 × 103

GP2 08/26/1998 1315 3.25 1.3 × 105 6.5 × 103

08/26/1998 1610 6.17 9.8 × 104 6.7 × 103

08/26/1998 1910 9.17 8.6 × 104 5.9 × 103

08/27/1998 0735 21.58 3.6 × 103 2.1 × 102

GP3 08/26/1998 1310 3.17 1.1 × 105 2.4 × 103

08/26/1998 1615 6.25 2.3 × 104 7.5 × 102

08/26/1998 1905 9.08 4.1 × 104 1.9 × 103

08/27/1998 0745 21.75 2.4 × 103 5.5 × 101

Appendix D. Measured bacteriophage concentrations for water samples collected during the 1998 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

MS2 PRD1

(pfu/mL)
52 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

Appendix E. Measured bromide concentrations for water samples collected during the 2000 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

Bromide

(mg/L)

PR12 08/03/2000 1600 0.50 185

08/03/2000 1700 1.50 95

08/03/2000 1800 2.50 80

08/03/2000 1900 3.50 90

08/03/2000 2000 4.50 86

08/03/2000 2100 5.50 85

08/03/2000 2200 6.50 86

08/03/2000 2300 7.50 81

08/04/2000 0000 8.50 80

08/04/2000 0100 9.50 82

08/04/2000 0200 10.50 93

08/04/2000 0300 11.50 95

08/04/2000 0400 12.50 86

08/04/2000 0500 13.50 86

08/04/2000 0600 14.50 84

08/04/2000 1200 20.50 68

08/04/2000 2000 28.50 36

08/04/2000 2200 30.50 33

08/05/2000 0000 32.50 29

08/05/2000 0745 40.25 23

08/05/2000 1230 45.00 14

08/05/2000 1800 50.50 9.1

08/06/2000 0600 62.50 4.9

08/06/2000 1200 68.50 2.9

08/06/2000 1800 74.50 2.2

08/07/2000 1230 93.00 .7

08/07/2000 1630 97.00 .6

08/08/2000 0800 112.50 .5

08/08/2000 1300 117.50 .4

08/08/2000 1700 121.50 .5

08/09/2000 0800 136.50 .5

08/10/2000 1150 164.33 .5

WP1 08/03/2000 1630 1.00 <0.3

08/03/2000 1900 3.50 1.1

08/03/2000 1910 3.67 2.9

08/03/2000 1922 3.87 9.2

08/03/2000 1930 4.00 23

08/03/2000 1940 4.17 50

08/03/2000 1950 4.33 71

08/03/2000 2000 4.50 94

08/03/2000 2015 4.75 124

08/03/2000 2030 5.00 165

08/03/2000 2045 5.25 190

Appendix E. Measured bromide concentrations for water samples collected during the 2000 tracer experiment from a research field site located in Los Angeles 

County, California

[hr, hour; mg/L, milligrams per liter]
Appendix E 53

08/03/2000 2100 5.50 210

08/03/2000 2115 5.75 210

08/03/2000 2130 6.00 190

08/03/2000 2145 6.25 180

08/03/2000 2200 6.50 145

08/03/2000 2300 7.50 92

08/04/2000 0000 8.50 81.3

08/04/2000 0100 9.50 83

08/04/2000 0200 10.50 80

08/04/2000 0300 11.50 80

08/04/2000 0400 12.50 81

08/04/2000 0500 13.50 78

08/04/2000 0600 14.50 80

08/04/2000 0800 16.50 80

08/04/2000 1000 18.50 81

08/04/2000 1200 20.50 79

08/04/2000 1400 22.50 79

08/04/2000 1600 24.50 78

08/04/2000 2000 28.50 63

08/04/2000 2200 30.50 54

08/05/2000 0000 32.50 42.3

08/05/2000 0800 40.50 29

08/05/2000 1800 50.50 14

08/06/2000 0600 62.50 12

08/06/2000 1800 74.50 3.1

08/08/2000 0800 112.50 .7

08/09/2000 0800 136.50 .8

WP2 08/03/2000 2130 6.00 <.3

08/03/2000 2200 6.50 <.3

08/03/2000 2300 7.50 .5

08/04/2000 0000 8.50 .5

08/04/2000 0100 9.50 .6

08/04/2000 0130 10.00 4.1

08/04/2000 0140 10.17 11

08/04/2000 0150 10.33 16

08/04/2000 0200 10.50 29

08/04/2000 0215 10.75 46

08/04/2000 0230 11.00 60

08/04/2000 0245 11.25 88

08/04/2000 0300 11.50 105

08/04/2000 0315 11.75 121

08/04/2000 0330 12.00 125

08/04/2000 0400 12.50 140

08/04/2000 0500 13.50 135

08/04/2000 0600 14.50 126

08/04/2000 0700 15.50 107

Appendix E. Measured bromide concentrations for water samples collected during the 2000 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

Bromide

(mg/L)
54 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

08/04/2000 0800 16.50 94

08/04/2000 0900 17.50 95

08/04/2000 1000 18.50 89

08/04/2000 1200 20.50 87

08/04/2000 1400 22.50 85

08/04/2000 1600 24.50 86

08/04/2000 2000 28.50 81

08/04/2000 2200 30.50 83

08/05/2000 0000 32.50 76

08/05/2000 1800 50.50 21

08/06/2000 0600 62.50 10

08/06/2000 1800 74.50 4.9

08/08/2000 0800 112.50 1.4

08/09/2000 0800 136.50 .7

08/10/2000 1130 164.00 <.3

WP7 08/04/2000 1300 21.50 <0.3

08/04/2000 1500 23.50 .7

08/04/2000 1700 25.50 6.2

08/04/2000 1745 26.25 10

08/04/2000 1800 26.50 10

08/04/2000 1815 26.75 13

08/04/2000 1830 27.00 14

08/04/2000 1900 27.50 19

08/04/2000 2000 28.50 22

08/04/2000 2200 30.50 21

08/05/2000 0000 32.50 25

08/05/2000 0845 41.25 58

08/05/2000 1245 45.25 59

08/05/2000 1800 50.50 58

08/06/2000 0600 62.50 36

08/06/2000 1158 68.47 34

08/06/2000 1800 74.50 22

08/07/2000 0815 88.75 8.8

08/07/2000 1230 93.00 7.1

08/07/2000 1630 97.00 5.7

08/08/2000 0800 112.50 2

08/08/2000 1300 117.50 1.8

08/08/2000 1700 121.50 1.5

08/09/2000 0830 137.00 .9

08/10/2000 1115 163.75 .9

PR9 08/04/2000 0730 16.00 .5

08/04/2000 1130 20.00 .5

08/04/2000 1300 21.50 .6

08/04/2000 1500 23.50 1.1

Appendix E. Measured bromide concentrations for water samples collected during the 2000 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

Bromide

(mg/L)
Appendix E 55

08/04/2000 1700 25.50 1.5

08/04/2000 2000 28.50 2.3

08/04/2000 2030 29.00 2.3

08/04/2000 2100 29.50 2.7

08/04/2000 2200 30.50 2.9

08/05/2000 0000 32.50 3.8

08/05/2000 0730 40.00 7

08/05/2000 1330 46.00 11

08/05/2000 1800 50.50 19

08/06/2000 0600 62.50 49

08/06/2000 1230 69.00 56

08/06/2000 1800 74.50 56

08/07/2000 1230 93.00 31

08/08/2000 0800 112.50 8.5

08/08/2000 1330 118.00 6.2

08/08/2000 1700 121.50 5

08/09/2000 0800 136.50 1.9

08/10/2000 1145 164.25 .5

PR11 08/04/2000 1130 20.00 <.3

08/04/2000 1300 21.50 .5

08/04/2000 1500 23.50 .5

08/04/2000 1700 25.50 .6

08/04/2000 2000 28.50 .5

08/04/2000 2200 30.50 1

08/05/2000 0000 32.50 4.2

08/05/2000 0815 40.75 14

08/05/2000 1230 45.00 31

08/05/2000 1800 50.50 55

08/06/2000 0600 62.50 64

08/06/2000 1200 68.50 56

08/06/2000 1800 74.50 43

08/07/2000 1230 93.00 17

08/08/2000 0820 112.83 3.7

08/08/2000 1300 117.50 2.8

08/08/2000 1700 121.50 1.9

08/09/2000 0800 136.50 .7

08/10/2000 1200 164.50 .4

GP1 08/03/2000 1630 1.00 140

08/03/2000 1645 1.25 167

08/03/2000 1700 1.50 155

08/03/2000 1722 1.87 160

08/03/2000 1800 2.50 152

08/03/2000 1835 3.08 158

08/03/2000 1900 3.50 156

08/03/2000 1936 4.10 90

08/03/2000 2000 4.50 80

Appendix E. Measured bromide concentrations for water samples collected during the 2000 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

Bromide

(mg/L)
56 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

08/03/2000 2100 5.50 88

08/03/2000 2200 6.50 80

08/03/2000 2300 7.50 78

08/04/2000 0000 8.50 81

08/04/2000 0100 9.50 84

08/04/2000 0200 10.50 82

08/04/2000 0300 11.50 84

08/04/2000 0400 12.50 85

08/04/2000 0500 13.50 83

08/04/2000 0600 14.50 83

08/04/2000 0700 15.50 81

08/04/2000 0800 16.50 79

08/04/2000 0900 17.50 85

08/04/2000 1000 18.50 82

08/04/2000 1100 19.50 77

08/04/2000 1200 20.50 74

08/04/2000 1500 23.50 69

08/04/2000 2100 29.50 39

08/05/2000 0000 32.50 34

08/05/2000 0600 38.50 23

08/05/2000 1800 50.50 9.8

08/06/2000 0600 62.50 4.8

08/06/2000 1800 74.50 2.2

GP2 08/03/2000 1635 1.08 .6

08/03/2000 1646 1.27 .4

08/03/2000 1700 1.50 8.7

08/03/2000 1726 1.93 60

08/03/2000 1800 2.50 150

08/03/2000 1838 3.13 130

08/03/2000 1900 3.50 97

08/03/2000 1934 4.07 95

08/03/2000 2000 4.50 82

08/03/2000 2100 5.50 81

08/03/2000 2200 6.50 82

08/03/2000 2300 7.50 81

08/04/2000 0000 8.50 82

08/04/2000 0100 9.50 79

08/04/2000 0200 10.50 77

08/04/2000 0300 11.50 80

08/04/2000 0400 12.50 62

08/04/2000 0500 13.50 77

08/04/2000 0600 14.50 90

08/04/2000 0700 15.50 81

08/04/2000 0800 16.50 89

Appendix E. Measured bromide concentrations for water samples collected during the 2000 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

Bromide

(mg/L)
Appendix E 57

08/04/2000 0900 17.50 91

08/04/2000 1000 18.50 81

08/04/2000 1100 19.50 82

08/04/2000 1200 20.50 70

08/04/2000 1500 23.50 73

08/04/2000 2100 29.50 40

08/05/2000 0000 32.50 37

08/05/2000 0600 38.50 26

08/05/2000 1800 50.50 12

08/06/2000 0600 62.50 5.9

08/06/2000 1800 74.50 2.5

GP3 08/03/2000 1800 2.50 <.3

08/03/2000 1840 3.17 .8

08/03/2000 1900 3.50 38.7

08/03/2000 1932 4.03 85

08/03/2000 2000 4.50 113.1

08/03/2000 2100 5.50 93.9

08/03/2000 2200 6.50 73

08/03/2000 2300 7.50 71.5

08/04/2000 0000 8.50 72

08/04/2000 0100 9.50 68.4

08/04/2000 0200 10.50 69.1

08/04/2000 0300 11.50 72.1

08/04/2000 0400 12.50 71.1

08/04/2000 0600 14.50 72.8

08/04/2000 0700 15.50 73.2

08/04/2000 0800 16.50 72.3

08/04/2000 0900 17.50 73.3

08/04/2000 1000 18.50 79.8

08/04/2000 1100 19.50 73.9

08/04/2000 1200 20.50 73.8

08/04/2000 1500 23.50 73.8

08/04/2000 2100 29.50 75.4

08/05/2000 0000 32.50 49

08/05/2000 0600 38.50 35.7

08/05/2000 1800 50.50 25.6

08/06/2000 0600 62.50 6.5

08/06/2000 1800 74.50 2.7

GP4 08/03/2000 1700 1.5 <.3

08/03/2000 1800 2.5 <.3

08/03/2000 1850 3.3 22.4

08/03/2000 1900 3.5 49.5

08/03/2000 1930 4 90.8

08/03/2000 2000 4.5 144

08/03/2000 2100 5.5 100.4

08/03/2000 2200 6.5 75.3

Appendix E. Measured bromide concentrations for water samples collected during the 2000 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

Bromide

(mg/L)
58 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

08/03/2000 2300 7.5 74.6

08/04/2000 0000 8.5 75.3

08/04/2000 0100 9.5 73.9

08/04/2000 0200 10.5 74.1

08/04/2000 0300 11.5 72.2

08/04/2000 0400 12.5 68.1

08/04/2000 0500 13.5 71.2

08/04/2000 0600 14.5 71.4

08/04/2000 0700 15.5 72.7

08/04/2000 0800 16.5 64.3

08/04/2000 0900 17.5 72.2

08/04/2000 1000 18.5 78.3

08/04/2000 1000 18.5 78.3

08/04/2000 1100 19.5 69.9

08/04/2000 1200 20.5 71

08/04/2000 1500 23.5 69.9

08/04/2000 2100 29.5 46

08/05/2000 0000 32.5 35.1

08/05/2000 0600 38.5 24.2

08/05/2000 1800 50.5 12

08/06/2000 0600 62.5 6.5

08/06/2000 1800 74.5 2.8

GP5 08/03/2000 1800 2.5 <.3

08/03/2000 1900 3.5 <.3

08/03/2000 1924 3.9 13

08/03/2000 2000 4.5 63.4

08/03/2000 2100 5.5 141.4

08/03/2000 2200 6.5 92.5

08/03/2000 2300 7.5 77.4

08/04/2000 0000 8.5 84.4

08/04/2000 0100 9.5 85.5

08/04/2000 0200 10.5 82.1

08/04/2000 0300 11.5 82.1

08/04/2000 0400 12.5 83.6

08/04/2000 0500 13.5 83.2

08/04/2000 0600 14.5 84.1

08/04/2000 0700 15.5 83.8

08/04/2000 0800 16.5 79.1

08/04/2000 0900 17.5 77.6

08/04/2000 1000 18.5 81.3

08/04/2000 1100 19.5 77.5

08/04/2000 1200 20.5 78.2

08/04/2000 1400 22.5 76

08/04/2000 1600 24.5 79.7

Appendix E. Measured bromide concentrations for water samples collected during the 2000 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

Bromide

(mg/L)
Appendix E 59

08/04/2000 2200 30.5 63.5

08/05/2000 0000 32.5 61.6

08/05/2000 1800 50.5 13

08/06/2000 0600 62.5 7.7

08/06/2000 1800 74.5 3.7

Appendix E. Measured bromide concentrations for water samples collected during the 2000 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

Bromide

(mg/L)
60 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

Appendix F. Measured bacteriophage concentrations for water samples collected during the 2000 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

MS2 PRD1

MPN(pfu/L)

PR12 08/03/2000 1600 0.5 9.50 × 107 1.26 × 107

08/03/2000 1700 1.5 6.60 × 107 4.70 × 106

08/03/2000 1900 3.5 4.42 × 107 5.95 × 106

08/03/2000 2100 5.5 6.30 × 107 1.16 × 107

08/03/2000 2200 6.5 6.40 × 107 6.60 × 106

08/03/2000 2300 7.5 5.90 × 107 5.40 × 106

08/04/2000 0000 8.5 1.05 × 108 7.15 × 106

08/04/2000 0100 9.5 8.25 × 107 4.85 × 106

08/04/2000 0200 10.5 4.35 × 107 3.40 × 106

08/04/2000 0300 11.5 6.35 × 107 8.40 × 106

08/04/2000 0400 12.5 5.05 × 107 2.17 × 106

08/04/2000 0500 13.5 5.50 × 107 2.09 × 106

08/04/2000 0600 14.5 6.70 × 107 2.06 × 106

08/04/2000 1200 20.5 1.56 × 107 2.42 × 106

08/04/2000 1800 26.5 4.10 × 106 1.67 × 105

08/05/2000 0000 32.5 2.74 × 106 1.15 × 105

08/05/2000 1230 45.0 1.90 × 105 7.00 × 103

08/05/2000 1800 50.5 5.15 × 104 2.50 × 103

08/06/2000 0600 62.5 1.70 × 104 <500

08/06/2000 1200 68.5 5.50 × 103 <500

08/06/2000 1800 74.5 1.00 × 103 <500

08/07/2000 1230 93.0 <500 <500

08/08/2000 1330 118.0 5.00 × 102 <500

08/09/2000 0830 137.0 5.00 × 102 <500

P2 08/03/2000 1600 .5 5.5 × 107 7.50 × 106

08/03/2000 1700 1.5 3.2 × 107 1.08 × 107

08/03/2000 1900 3.5 3.4 × 107 9.60 × 106

P3 08/03/2000 1600 .5 1.1 × 108 2.44 × 107

08/03/2000 1700 1.5 4.8 × 107 6.60 × 106

08/03/2000 1900 3.5 5.1 × 107 5.65 × 106

P4 08/03/2000 1600 .5 5.8 × 107 1.23 × 107

08/03/2000 1700 1.5 2.4 × 107 5.15 × 106

08/03/2000 1900 3.5 3.4 × 107 1.01 × 107

WP1 08/03/2000 1900 3.5 1.2 × 104 <500

08/03/2000 2000 4.5 3.1 × 105 5.0 × 102

08/03/2000 2100 5.5 3.4 × 105 <500

08/03/2000 2200 6.5 3.9 × 105 5.0 × 102

08/03/2000 2300 7.5 5.6 × 105 <500

08/04/2000 0000 8.5 4.8 × 105 <500

08/04/2000 0100 9.5 4.3 × 105 5.0 × 102

08/04/2000 0200 10.5 3.8 × 105 <500

Appendix F. Measured bacteriophage concentrations for water samples collected during the 2000 tracer experiment from a research field site located in Los 

Angeles County, California

[hr, hour; MPN, most probable number; pfu/L, plaque forming units per liter]
Appendix F 61

08/04/2000 0300 11.5 9.8 × 105 <500

08/04/2000 0400 12.5 8.9 × 105 <500

08/04/2000 0500 13.5 6.7 × 105 <500

08/04/2000 0600 14.5 2.0 × 105 <500

08/04/2000 0800 16.5 1.0 × 105 <500

08/04/2000 1000 18.5 1.4 × 105 <500

08/04/2000 1400 22.5 1.6 × 105 <500

08/04/2000 1800 26.5 2.3 × 105 5.0 × 102

08/04/2000 2200 30.5 1.5 × 105 <500

08/05/2000 0000 32.5 1.0 × 105 <500

08/05/2000 0800 40.5 7.8 × 104 <500

08/05/2000 1800 50.5 3.3 × 104 <500

08/06/2000 0600 62.5 7.5 × 103 <500

08/06/2000 1800 74.5 5.0 × 103 <500

08/10/2000 1120 163.8 <500 <500

WP2 08/03/2000 2300 7.5 <500 <500

08/04/2000 0000 8.5 <500 <500

08/04/2000 0100 9.5 <500 <500

08/04/2000 0200 10.5 <500 <500

08/04/2000 0300 11.5 1.1 × 104 <500

08/04/2000 0400 12.5 3.1 × 104 <500

08/04/2000 0500 13.5 4.3 × 104 <500

08/04/2000 0600 14.5 7.4 × 104 <500

08/04/2000 0700 15.5 3.9 × 104 <500

08/04/2000 0800 16.5 6.6 × 104 <500

08/04/2000 0900 17.5 3.2 × 104 <500

08/04/2000 1000 18.5 7.0 × 104 <500

08/04/2000 1200 20.5 3.5 × 104 <500

08/04/2000 1400 22.5 4.7 × 104 <500

08/04/2000 1600 24.5 6.3 × 104 <500

08/04/2000 1800 26.5 4.1 × 104 5.0 × 102

08/04/2000 2000 28.5 3.8 × 104 <500

08/04/2000 2200 30.5 3.0 × 104 5.0 × 102

08/05/2000 0000 32.5 3.3 × 104 <500

08/05/2000 0805 40.6 2.1 × 104 <500

08/05/2000 1800 50.5 7.5 × 103 <500

08/06/2000 0600 62.5 1.1 × 104 <500

08/06/2000 1800 74.5 5.5 × 103 <500

08/10/2000 1130 164.0 <500 <500

WP7 08/04/2000 2000 28.50 >161 9.0 × 10−1

08/04/2000 2200 30.50 1.6 × 102 7.9 × 10−1

08/05/2000 0000 32.50 2.3 × 101 <.2

08/05/2000 0600 38.50 >161 1.8 × 10−1

08/05/2000 1200 44.50 >161 1.8 × 10−1

08/05/2000 1800 50.50 >161 1.8 × 10−1

Appendix F. Measured bacteriophage concentrations for water samples collected during the 2000 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

MS2 PRD1

MPN(pfu/L)
62 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

08/06/2000 0715 63.75 3.5 × 103 <.2

08/06/2000 1200 68.50 7.9 × 102 <.2

08/06/2000 1800 74.50 >161 <.2

08/07/2000 0815 88.75 2.3 × 102 2.0 × 10−1

08/07/2000 1245 93.25 2.3 × 102 <.2

08/07/2000 1630 97.00 1.6 × 103 <.2

08/08/2000 0800 112.50 >1610 <.2

08/08/2000 1330 118.00 1.3 × 102 <.2

08/08/2000 1700 121.50 2.4 × 102 <.2

08/09/2000 0830 137.00 1.3 × 102 <.2

08/10/2000 1115 163.75 1.3 × 103 <.2

PR9 08/04/2000 2000 28.50 >161 4.1 × 100

08/04/2000 2200 30.50 >161 2.4 × 101

08/05/2000 0000 32.50 >161 1.4 × 100

08/05/2000 0600 38.50 3.6 × 101 4.0 × 10−1

08/05/2000 1200 44.50 >161 3.7 × 10−1

08/05/2000 1800 50.50 4.9 × 100 2.0 × 10−1

08/06/2000 0630 63.00 7.9 × 101 <.2

08/06/2000 1200 68.50 1.3 × 101 <.2

08/06/2000 1800 74.50 5.4 × 101 <.2

08/07/2000 0800 88.50 5.4 × 101 6.0 × 10−1

08/07/2000 1245 93.25 1.6 × 102 <.2

08/07/2000 1630 97.00 1.6 × 102 4.9 × 100

08/08/2000 0820 112.83 5.4 × 101 <.2

08/08/2000 1330 118.00 3.5 × 101 <.2

08/08/2000 1700 121.50 5.4 × 101 <.2

08/09/2000 0845 137.25 2.4 × 101 <.2

08/10/2000 1145 164.25 2.8 × 101 <.2

PR11 08/04/2000 2000 28.50 >161 2.1 × 100

08/04/2000 2200 30.50 >161 1.3 × 101

08/05/2000 0000 32.50 >161 2.0 × 100

08/05/2000 0600 38.50 >161 3.7 × 10−1

08/05/2000 1200 44.50 3.5 × 101 <.2

08/05/2000 1800 50.50 4.9 × 100 5.0 × 10−1

08/06/2000 0700 63.50 9.3 × 100 <.2

08/06/2000 1200 68.50 2.0 × 100 <.2

08/06/2000 1800 74.50 3.5 × 101 <.2

08/07/2000 0830 89.00 2.4 × 101 8.0 × 10−1

08/07/2000 1245 93.25 5.4 × 101 2.0 × 10−1

08/07/2000 1630 97.00 3.0 × 101 7.0 × 10−1

08/08/2000 0835 113.08 3.5 × 101 <.2

08/08/2000 1330 118.00 2.0 × 101 <.2

08/08/2000 1700 121.50 7.9 × 100 <.2

Appendix F. Measured bacteriophage concentrations for water samples collected during the 2000 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

MS2 PRD1

MPN(pfu/L)
Appendix F 63

08/09/2000 0900 137.50 3.5 × 101 5.0 × 10−1

08/10/2000 1200 164.50 1.7 × 101 <.2

GP1 08/03/2000 1645 1.2 4.2 × 106 4.2 × 105

08/03/2000 1700 1.5 3.4 × 106 4.1 × 105

08/03/2000 1900 3.5 8.5 × 106 7.0 × 105

08/03/2000 2000 4.5 8.7 × 106 1.2 × 105

08/03/2000 2100 5.5 5.0 × 106 5.2 × 105

08/03/2000 2200 6.5 9.1 × 106 8.2 × 104

08/03/2000 2300 7.5 6.4 × 106 4.6 × 105

08/04/2000 0000 8.5 9.7 × 106 1.4 × 105

08/04/2000 0100 9.5 7.3 × 106 9.2 × 104

08/04/2000 0200 10.5 8.7 × 106 1.3 × 105

08/04/2000 0300 11.5 6.5 × 106 1.1 × 105

08/04/2000 0400 12.5 7.0 × 106 1.7 × 105

08/04/2000 0500 13.5 5.1 × 106 6.5 × 104

08/04/2000 0700 15.5 3.1 × 106 2.2 × 105

08/04/2000 0800 16.5 3.2 × 106 2.3 × 105

08/04/2000 1100 19.5 2.9 × 106 1.9 × 105

08/04/2000 1800 26.5 8.2 × 105 6.3 × 104

08/04/2000 2100 29.5 3.8 × 105 2.2 × 104

08/05/2000 0600 38.5 5.8 × 105 1.3 × 104

08/05/2000 1800 50.5 7.6 × 104 6.0 × 103

08/06/2000 0600 62.5 2.9 × 104 4.0 × 103

08/06/2000 1800 74.5 1.3 × 104 5.0 × 103

GP2 08/03/2000 1645 1.25 4.5 × 103 1.0 × 103

08/03/2000 1700 1.50 2.7 × 104 5.0 × 102

08/03/2000 1800 2.50 1.6 × 105 <500

08/03/2000 1900 3.50 6.2 × 105 2.0 × 103

08/03/2000 2000 4.50 6.3 × 105 1.0 × 103

08/03/2000 2100 5.50 6.1 × 105 2.0 × 103

08/03/2000 2300 7.50 7.6 × 105 1.5 × 103

08/04/2000 0100 9.50 5.3 × 105 <500

08/04/2000 0300 11.50 1.1 × 106 2.0 × 103

08/04/2000 0500 13.50 4.9 × 105 1.0 × 103

08/04/2000 0700 15.50 4.7 × 105 2.5 × 103

08/04/2000 0900 17.50 1.1 × 105 <500

08/04/2000 1000 18.50 4.4 × 104 <500

08/04/2000 1100 19.50 2.5 × 105 <500

08/04/2000 1500 23.50 2.3 × 105 5.0 × 102

08/04/2000 1800 26.50 1.0 × 105 5.0 × 102

08/04/2000 2100 29.50 7.1 × 104 5.0 × 102

08/05/2000 0600 38.50 4.3 × 104 <500

08/05/2000 1800 50.50 1.5 × 104 5.0 × 102

08/06/2000 0600 62.50 5.5 × 103 5.0 × 102

08/06/2000 1800 74.50 6.0 × 103 <500

Appendix F. Measured bacteriophage concentrations for water samples collected during the 2000 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

MS2 PRD1

MPN(pfu/L)
64 Virus Fate and Transport During Recharge Using Recycled Water at a Research Field Site, Los Angeles County, California

GP3 08/03/2000 1700 1.50 <500 <500

08/03/2000 1800 2.50 <500 <500

08/03/2000 1900 3.50 2.5 × 104 <500

08/03/2000 2000 4.50 7.0 × 103 <500

08/03/2000 2100 5.50 5.0 × 103 <500

08/03/2000 2200 6.50 1.3 × 104 <500

08/03/2000 2300 7.50 1.8 × 104 <500

08/04/2000 0000 8.50 5.5 × 104 <500

08/04/2000 0100 9.50 5.2 × 104 <500

08/04/2000 0200 10.50 6.3 × 104 <500

08/04/2000 0300 11.50 4.9 × 104 <500

08/04/2000 0500 13.50 5.1 × 104 <500

08/04/2000 0700 15.50 2.6 × 104 <500

08/04/2000 0800 16.50 5.5 × 104 <500

08/04/2000 1100 19.50 1.3 × 104 <500

08/04/2000 1500 23.50 9.5 × 103 <500

08/04/2000 1800 26.50 1.6 × 104 <500

08/04/2000 2100 29.50 1.7 × 104 <500

08/05/2000 0000 32.50 1.8 × 104 <500

08/05/2000 0600 38.50 1.1 × 104 <500

08/05/2000 1800 50.50 1.2 × 104 <500

08/06/2000 0600 62.50 1.5 × 103 <500

08/06/2000 0075 74.50 1.5 × 103 <500

GP4 08/03/2000 1700 1.50 <500 <500

08/03/2000 1800 2.50 <500 <500

08/03/2000 1900 3.50 1.5 × 103 <500

08/03/2000 2000 4.50 3.5 × 103 <500

08/03/2000 2100 5.50 6.5 × 103 <500

08/03/2000 2200 6.50 2.0 × 104 <500

08/03/2000 2300 7.50 2.1 × 104 <500

08/04/2000 0000 8.50 2.0 × 104 <500

08/04/2000 0100 9.50 8.5 × 103 5.0 × 102

08/04/2000 0200 10.50 2.0 × 104 <500

08/04/2000 0300 11.50 3.7 × 104 <500

08/04/2000 0500 13.50 2.8 × 104 <500

08/04/2000 0700 15.50 1.2 × 104 <500

08/04/2000 0800 16.50 1.5 × 104 <500

08/04/2000 1100 19.50 4.5 × 103 <500

08/04/2000 1500 23.50 6.5 × 103 <500

08/04/2000 1800 26.50 6.5 × 103 <500

08/04/2000 2100 29.50 1.3 × 104 <500

08/05/2000 0000 32.50 4.0 × 103 <500

08/05/2000 0600 38.50 5.0 × 103 <500

08/05/2000 1800 50.50 3.0 × 103 <500

Appendix F. Measured bacteriophage concentrations for water samples collected during the 2000 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

MS2 PRD1

MPN(pfu/L)
Appendix F 65

08/06/2000 0600 62.50 3.0 × 103 <500

08/06/2000 0075 74.50 1.0 × 103 <500

GP5 08/03/2000 1800 2.50 <500 <500

08/03/2000 1900 3.50 <500 <500

08/03/2000 2000 4.50 5.0 × 102 <500

08/03/2000 2100 5.50 3.0 × 103 <500

08/03/2000 2200 6.50 1.5 × 103 <500

08/03/2000 2300 7.50 4.0 × 103 <500

08/04/2000 0000 8.50 2.4 × 104 <500

08/04/2000 0100 9.50 2.0 × 103 <500

08/04/2000 0200 10.50 1.5 × 103 <500

08/04/2000 0300 11.50 5.5 × 103 <500

08/04/2000 0400 12.50 5.0 × 103 <500

08/04/2000 0500 13.50 2.0 × 103 <500

08/04/2000 0600 14.50 2.5 × 103 <500

08/04/2000 0700 15.50 2.0 × 103 <500

08/04/2000 0800 16.50 1.5 × 104 <500

08/04/2000 1100 19.50 3.5 × 103 <500

08/04/2000 1400 22.50 1.1 × 104 <500

08/04/2000 1600 24.50 5.0 × 102 <500

08/04/2000 1800 26.50 1.5 × 103 <500

08/04/2000 2000 28.50 <500 <500

08/04/2000 2200 30.50 6.5 × 103 <500

08/05/2000 0000 32.50 3.0 × 103 <500

08/05/2000 0600 38.50 1.0 × 103 <500

08/05/2000 1800 50.50 5.0 × 102 <500

08/06/2000 0025 62.50 <500 <500

08/06/2000 0075 74.50 1.0 × 103 <500

Appendix F. Measured bacteriophage concentrations for water samples collected during the 2000 tracer experiment from a research field site located in Los 

Angeles County, California—Continued

Sample Date and time collected Elapsed time

(hr)

MS2 PRD1

MPN(pfu/L)