.A

U.S. Department of the Interior 

U.S. Geological Survey

Prepared in cooperation with the 

City of Newport News

Dissolved Organic Carbon and Disinfection 

By-Product Precursors in Waters of the 

Chickahpminy River Basin, Virginia, and 

Implications for Public Supply

Water-Resources Investigations Report 00-4175

science 

uses

for a changing world

U.S. Department of the Interior 

U.S. Geological Survey

Dissolved Organic Carbon and Disinfection 

By-Product Precursors in Waters of the 

Chickahpminy River Basin, Virginia, and 

Implications for Public Supply

By Gary K. Speiran

Water-Resources Investigations Report 00-4175

Prepared in cooperation with the 

City of Newport News

Richmond, Virginia 

2000
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBTTT, Secretary

U.S. GEOLOGICAL SURVEY 

Charles G. Groat, Director

The use of trade or product names in this report is for identification 

purposes only and does not constitute endorsement by the 

U.S. Geological Survey.

For additional information write to:

District Chief 

U.S. Geological Survey 

1730 East Parham Road 

Richmond, VA 23228-2202

Copies of this report can be purchased from:

U.S. Geological Survey 

Branch of Information Services 

Box 25286, Federal Center 

Denver, CO 80225-0286
CONTENTS

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

Introduction ................................................................................. 2

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

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

Description of Study Area .......................................................................................................................................... 4

Acknowledgments ...................................................................................................................................................... 5

Study Methods ........................................................................................................................................................^ 5

Field Studies ............................................................................................................................................................... 6

Stream-Water Sampling ................................................................................................................................... 6

Ground-Water Sampling ................................................................................................................................... 8

Isotope Analysis ............................................................................................................................................... 9

Laboratory Studies ..................................................................................................................................................... 12

Stream-Bed Detritus ......................................................................................................................................... 12

Degradation of Dissolved Organic Carbon ...................................................................................................... 12

Basin Hydrology .................................................................................................................................................................. 13

Surface Water ............................................................................................................................................................^ 14

Evaporation ................................................................................................................................................................ 16

Ground Water ............................................................................................................................................................. 16

Light Absorbance at 253.7 Nanometers (UV254) as a Surrogate Analyte ........................................................................... 19

Dissolved Organic Carbon (DOC) and Disinfection By-Product (DBP) Precursors ........................................................... 20

Contributions of Stream-Bed Detritus to DOC in Stream Water ............................................................................... 24

Degradation of DOC in Stream Water ........................................................................................................................ 26

Temporal and Spatial Variability in Concentrations of DOC and DBP Precursors in Stream Water ......................... 28

Base-Flow Periods ............................................................................................................................................ 28

Ground-Water Sources ..................................................................................................................................... 28

Stormflow Periods ............................................................................................................................................ 32

Implications for Public Supply ............................................................................................................................................. 36

Summary and Conclusions ................................................................................................................................................... 40

References Cited .................................................................................................................................................................. 41

Appendix ................................................................................. 45

FIGURES

1. Map showing location and features of study area and location of surface-water sample collection

stations, Chickahominy River Basin, Virginia ......................................................................................................... 3

2-4. Schematics showing:

2. Conceptualized stream and ground-water interaction for a stream partly incised through the upland 

water-table aquifer (A), and for a stream fully incised through the upland water-table aquifer 

and into the confining unit (B) .......................................................................................................................... 10

3. General locations of the flood plain, uplands, seeps, wells, and the surface-water quality station in

part of the watershed of the tributary to Schiminoe Creek ............................................................................... 11

4. Treatment of water samples to evaluate degradation of dissolved organic carbon ........................................... 13

5-17. Graphs showing:

5. Relation of oxygen-18 and deuterium in streams showing the effects of evaporation (A) and in

ground water (B) ............................................................................................................................................... 17

6. Relation of light absorbance at 253.7 nanometers and dissolved organic carbon concentrations

for October 1996 (A), May 1997 (B), and all data (C) ..................................................................................... 21

Contents I
7. Relation of light absorbance at 253.7 nanometers and trihalomethane formation potential

concentrations for August 1996 (A), December 1996 (B), and all data (C) ...................................................... 22

8. Relation of light absorbance at 253.7 nanometers and total organic halide formation potential

concentrations for November 1997 (A), March 1996 (B), and all data (C) ...................................................... 23

9. Relation of light absorbance at 253.7 nanometers and haloacetic acid formation potential

concentrations for all data ................................................................................................................................. 24

10. Change in light absorbance at 253.7 nanometers of organic-carbon-free water incubated with

small branches, leaves, and porous wood ......................................................................................................... 25

11. Changes in light absorbance at 253.7 nanometers of replicate samples ........................................................... 27

12. Downstream changes in light absorbance at 253.7 nanometers in cold-weather months (A), 

light absorbance at 253.7 nanometers in warm-weather months (B), concentrations 

of dissolved organic carbon (C), concentrations of trihalomethane formation potential (D), 

concentrations of total organic halide formation potential (E), and concentrations of 

haloacetic acid formation potential (F) at base flow ......................................................................................... 29

13. Light absorbance at 253.7 nanometers (A) and concentrations of dissolved organic carbon (B), 

trihalomethane formation potential (C), total organic halide formation potential (D), and 

haloacetic acid formation potential (E) at the tributary and main-stem stations in downstream 

sequence number (Table 1) during synoptic sample-collection periods ........................................................... 30

14. Changes in streamflow and light absorbance at 253.7 nanometers during the 1997

summer storm at station CR02 ......................................................................................................................... 34

15. Relation of oxygen-18 and deuterium for the 1997 summer storm (A) and relation of oxygen-18

and deuterium for the 1997 summer and 1998 winter storms (B) at station CR02 .......................................... 35

16. Relation of streamflow and light absorbance at 253.7 nanometers (A) and concentrations of 

dissolved organic carbon (B), trihalomethane formation potential (C), and total organic 

halide formation potential (D) during the 1998 winter stormflow sample-collection 

period at station CR02 ...................................................................................................................................... 37

17. Percentage of total organic halide formation potential consisting of trihalomethane formation

potential in samples .......................................................................................................................................... 39

TABLES

1. Characteristics of water-sample collection stations ................................................................................................. 7

2. Streamflow characteristics at station CR02 for the period of record and for each year of the study period ........... 14

.3. Streamflow characteristics at stations CR87, UPB01, and CR02 ............................................................................ 15

4. Statistical relations between light absorbance at 253.7 nanometers and concentrations of 

dissolved organic carbon, trihalomethane formation potential, and total organic 

halide formation potential for surface-water samples .............................................................................................. 19

5. Fraction of original light absorbance at 253.7 nanometers and concentrations of organic 

carbon and trihalomethane formation potential remaining at the end of the laboratory 

study of the degradation of organic carbon in water collected October 1997 from station CNSO1 ........................ 26

6. Summary of light absorbance at 253.7 nanometers and concentrations of dissolved organic carbon 

of ground water from the upland water-table aquifer, ground water from wells and seeps in the 

alluvial water-table aquifer, and stream water during base-flow periods at stations SCT01 and CR02 .................. 31

7. Timing of peak in light absorbance at 253.7 nanometers and concentrations of dissolved organic carbon, 

trihalomethane formation potential, total organic halide formation potential, and haloacetic acid formation 

potential in relation to peak streamflow at selected stations during selected stormflow periods ............................. 33

8. Stage, light absorbance at 253.7 nanometers, and concentrations of dissolved organic carbon, trihalomethane 

formation potential, total organic halide formation potential, and haloacetic acid formation potential at 

initial, peak, and after peak flow of selected stormflow periods at stations CR87, WOS55, and CR02 ................. 38

II Contents
CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATED WATER-QUALITY UNITS

Multiply By To obtain

Measurements Reported in Inch-Pound Units

Length

inch (in.)

foot (ft)

mile (mi)

square mile (mi2)

inch per year (in/yr)

million gallons per day (Mgal/d)

cubic foot per second (ft3/5)

foot per second (ft/s)

2.54

0.3048

1.609

Area

2.590

Flow

25.40

3,785

0.028317

Velocity (Speed)

0.3048

centimeter

meter

kilometer

square kilometer

millimeter per day

cubic meter per day

cubic meter per second

meter per second

Measurements Reported in International System Units

nanometers (nm)

micrometer (|o.m)

centimeter (cm)

milliliter (mL) 

liter (L)

Length

0.00000003937 inch

0.00003937 inch

0.3937 inch

Volume

0.0002642

0.2642

gallon 

gallon

Water temperature is reported in degrees Celsius (C), which can be converted to degrees Fahrenheit (F) as follows: °F = (1.8 x °C) + 32

Vertical datum: 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.

Abbreviated water-quality units: Chemical concentration is reported in milligrams per liter (mg/L) or micrograms per liter (|o.g/L). Milligrams per 

liter is a unit expressing the concentration of chemical constituents in solution as mass (milligrams) of solute per unit volume (liter) of water. One 

thousand micrograms per liter is equivalent to one milligram per liter. For concentrations less than 7,000 mg/L, the numerical value is the same 

as for concentrations in parts per million. Specific electrical conductance of water is reported in microsiemens per centimeter at 25 degrees 

Celsius (nS/cm). Stable-isotope concentration is reported in per mil, which is equivalent to parts per thousand.

Contents

Dissolved Organic Carbon and Disinfection By-Product 

Precursors in Waters of the Chickahominy River Basin, 

Virginia, and Implications for Public Supply

By Gary K. Speiran

ABSTRACT

Surface water that is treated for use in public 

supplies typically is disinfected with chlorine to 

help ensure potability. When water containing 

dissolved organic carbon (DOC) is chlorinated, 

chlorinated disinfection by-products (DBFs), such 

as trihalomethanes, are formed. Many of these 

DBFs are carcinogenic. Only certain types of 

dissolved organic compounds, however, produce 

DBFs; these compounds are commonly called 

DBF precursors. Water treatment removes a large 

part of the DOC from the water but cannot 

selectively remove DBF precursors. Although 

treating water before chlorination reduces 

concentrations of DBFs in finished water, 

concentrations can still exceed drinking-water 

standards. Knowledge of factors affecting the 

spatial and temporal variability in concentrations 

of DBF precursors in source waters will allow 

utilities to withdraw water when concentrations 

are low. This strategy will facilitate water 

treatment, reduce water-treatment costs, and 

provide finished water having lower 

concentrations of DBFs.

Results of field and laboratory studies 

conducted from April 1995 through September 

1998 were used to evaluate spatial and temporal 

variability in concentrations of DOC and DBF 

precursors in the Chickahominy River Basin, a 

raw-water source for the City of Newport News, 

Va. During base-flow periods, concentrations of 

DOC and DBF precursors decreased as much as 

50 percent where the river flowed through 

extensive wetlands. During stormflow periods,

concentrations of DOC and DBF precursors 

increased to peak values at, or following, peak 

streamflow.

Variability in concentrations of DOC and 

DBF precursors in stream water depended on 

hydrologic conditions. During base-flow periods, 

ground-water discharge and stream-bed detritus 

were the principal sources of DOC and DBF 

precursors to the streams, while organic litter 

distributed across the wetlands was only an 

indirect source because it had little contact with 

stream water. Concentrations of DOC and DBF 

precursors decreased downstream because of 

dilution from tributary inflow having a low organic 

content and because of decomposition of DOC as 

water flowed through the broad and shallow 

channels of the Coastal Plain reaches of the 

Chickahominy River.

During stormflow periods, infiltrating 

precipitation leached DOC and DBF precursors 

from the organic litter into the soil and shallow 

ground water. Discharge of DOC and DBF 

precursors with interflow and shallow ground 

water likely accounts for the peak in 

concentrations of DOC and DBF precursor at, or 

following, the peak in streamflow.

Study results have important implications 

for the use of water for public supply. Water 

treatment costs would be reduced and 

concentrations of DOC and DBFs in finished 

water would be lower if (1) withdrawal points are 

placed as far downstream as possible and (2) water 

is withdrawn and stored during the early parts of 

stormflow periods and withdrawal is discontinued 

when concentrations of DOC and DBF precursors 

increase.

Abstract 1
INTRODUCTION

Surface waters used for public supplies are 

commonly disinfected with chlorine to help ensure 

potability. When the water contains dissolved organic 

carbon (DOC), however, the chlorine and other 

halogens (primarily bromine) introduced by the 

disinfection process react with the organic carbon to 

produce a variety of halogenated organic compounds, 

commonly referred to as disinfection by-products 

(DBFs). Many of these DBFs are known, or suspected, 

carcinogens (U.S. Environmental Protection Agency, 

1998).

The presence of DOC in raw water supplies 

presents treatment problems even if disinfection 

methods are used that do not form DBFs. DOC reacts 

with metal coagulants and oxidants used in the 

production of potable water. Thus, higher DOC 

concentrations require more chemicals for treatment, 

thereby increasing water-treatment costs. DOC also can 

impart unpleasant color, taste, and odor to the water. 

Consequently, knowledge of the occurrence of DOC 

and the processes that affect the concentration of DOC 

in raw water is needed to facilitate water treatment and 

minimize water-treatment costs.

In 1998, the City of Newport News, Va., used 

about 52 Mgal/d of water; approximately 43 percent of 

the raw water was withdrawn from the Chickahominy 

River at Walkers Dam (fig. 1) (Ronald E. Harris, City 

of Newport News, Planning and Programs, oral 

commun., 1999). Withdrawal from the river is not 

allowed to reduce streamflow below 10 ft3/s at the dam. 

The Chickahominy River flows through extensive 

wetlands (primarily bottomland hardwood wetlands) in 

central Virginia and has a dark brown, "tea" color, 

indicative of the presence of humic substances. 

Withdrawn water can be stored in a network of 

reservoirs having a hydraulic retention time of 100 

days or more, or the water can be pumped directly to 

terminal reservoirs that have hydraulic retention times 

of approximately 30 days prior to treatment. 

Consequently, the city has the following options: (1) 

pump water containing low concentrations of DOC into 

the main reservoirs for later use; (2) pump water 

containing high concentrations of DOC into the main 

reservoirs for later use, thereby allowing natural 

processes within the reservoirs to reduce 

concentrations of DOC; or (3) pump water containing 

low or high concentrations of DOC into terminal 

reservoirs for more immediate use. Stored water can be

used during times when water in the Chickahominy 

River has high, or difficult to remove, concentrations of 

DOC or when streamflow in the river is low.

The U.S. Geological Survey (USGS), in 

cooperation with the City of Newport News, Va., 

conducted a study from April 1995 through September 

1998 to evaluate spatial and temporal variations in the 

DOC content of waters of the Chickahominy River 

Basin. This study focused on the effects of different 

hydrologic conditions on the potential formation of 

DBPs.

PURPOSE AND SCOPE

The purpose of this report is to describe spatial 

and temporal variability in concentrations of DOC and 

DBP precursors in the Chickahominy River Basin 

during base-flow and stormflow periods and to identify 

the processes that likely affect the variability. 

Characteristics of DOC are presented that serve as 

indicators of the amount of DBPs likely to form when 

the water is chlorinated. Strategies to reduce watertreatment costs by adjusting operations to account for 

variability in the DOC content of the raw water also are 

discussed.

Descriptions are based on results of field and 

laboratory studies conducted from April 1995 through 

September 1998. Surface-water sampling was 

conducted to evaluate spatial and temporal variability 

in DOC and DBP precursors in stream water from the 

Chickahominy River Basin during base-flow and 

stormflow periods. Data were collected at main-stem 

and tributary stations throughout the basin upstream of 

Walkers Dam. Samples were collected quarterly during 

base-flow and during selected stormflow periods. 

Samples of ground water were collected from wells and 

seeps in a sub-basin near the middle of the 

Chickahominy River Basin to investigate ground water 

as a transport pathway for DOC to streams. Laboratory 

studies also were conducted to evaluate (1) the 

contribution of stream-bed detritus to the DOC content 

of stream water and (2) the degradation of DOC in 

stream water.

Background

Rook (1974) determined that the chlorination of 

water containing DOC produces several halogenated 

organic compounds that are volatile and have a low

2 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
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molecular weight. These compounds include carbon 

tetrachloride (CCU) and the trihalomethanes (THMs) 

chloroform (CHCls) (the primary product), 

dichlorobromomethane (CHC^Br), 

chlorodibromomethane (CHClBr2), and bromoform 

(CHBrs). Chlorination also produces a mixture of nonvolatile, high molecular weight, halogenated organic 

compounds (Johnson and Jensen, 1995).

Environmental regulations, however, have 

targeted THMs. A drinking-water standard, also known 

as a maximum contaminant level (MCL), of 100 M-g/L 

was first established for THMs and has been lowered to 

80 |ig/L (U.S. Environmental Protection Agency, 

1998). An MCL of 60 flg/L also has been established 

for the sum of the concentrations of five haloacetic 

acids (HAA5): monochloroacetic acid, dichloroacetic 

acid, trichloroacetic acid, monobromoacetic acid, and 

dibromoacetic acid. These also are low molecular 

weight compounds. Although an MCL has not been 

established, the combination of all halogenated organic 

compounds is commonly referred to as total organic 

halides (TOXs).

Researchers have attempted to identify those 

types of dissolved organic compounds that are 

precursors to the formation of THMs and other DBFs. 

Although tannic acid (Youseffi and others, 1978) and 

nitrogen-containing organic compounds (Morris and 

Baum, 1978) have been shown to contribute to the 

formation of DBFs, much of the research has focused 

on the role of humic substances in producing DBFs 

(Rook, 1974; Oliver and Visser, 1980; Oliver and 

Thurman, 1981; Saito and others, 1989). Humic 

substances are naturally occurring, high molecularweight, organic substances that consist of humic acids 

(humic substances insoluble below pH 2) and fulvic 

acids (humic substances soluble throughout the pH 

range) (Aiken and others, 1985). Humic substances 

generally contribute from 40 to 60 percent of the DOC 

in natural waters (Thurman, 1985). Oliver and Visser 

(1980) determined that humic and fulvic acids in 

stream and lake water produce chloroform at similar 

rates per mass of the acid. Fulvic acids, however, 

produced much more chloroform than humic acids 

because fulvic acids dominate the composition of 

humic substances in water. The relations of chloroform 

production by humic and fulvic acids are consistent 

through the full range of molecular weights of the 

acids. The production of chloroform, however, was

greatest for those humic substances having a molecular 

weight of 1,000 to 10,000 units and decreased rapidly 

as the molecular weight increased to 30,000 units.

Because of the variety of organic substances that 

are precursors to the formation of THMs and other 

DBFs, the use of surrogate analyses has been studied as 

a way to evaluate the likelihood of the formation of 

large concentrations of DBFs. For example, the 

absorbance of light at 253.7 nanometers (referred to as 

UV254) by water commonly correlates with the 

presence of precursors to the formation of THMs and 

other organic halides (Singer and others, 1981; 

Edzwald and others, 1985); this determination, 

therefore, is frequently used as such a surrogate for the 

precursors. Although strong correlations may exist 

between UV254 and DBF formation potential, UV254 

is a measure of only one characteristic of the DOC; this 

characteristic does not necessarily contribute to the 

formation of DBFs. Thus, changes in the reactivity of 

the DOC with chlorine can differ from changes in 

UV254, thereby limiting the use of UV254 as a 

surrogate. The effectiveness of UV254 as a surrogate, 

therefore, likely depends on the system and the 

hydrologic conditions being studied.

Because commonly used treatment processes 

cannot selectively remove DBF precursors, all of the 

DOC must be treated to produce the lowest possible 

concentrations of DBFs in finished water supplies. 

Thus, the cost of removal of DBF precursors is heavily 

influenced by the total amount of DOC in the raw 

water. In general, high molecular-weight organic 

compounds are less soluble and more easily removed 

from water by conventional water-treatment processes 

than low molecular-weight organic compounds. 

Because the low molecular-weight compounds tend to 

form more DBFs (Oliver and Visser, 1980), as well as 

being more difficult to remove, reducing the 

concentration of DBFs in treated water supplies can be 

difficult and costly.

Description of Study Area

More than 80 percent of the Chickahominy River 

Basin lies within the Coastal Plain Physiographic 

Province in eastern Virginia (fig. 1). The headwaters of 

the river are in the Piedmont Physiographic Province, 

where consolidated bedrock is overlain by weathered 

rock (saprolite). Saprolite largely consists of silt and 

clay that contain variable amounts of sand. The

4 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
thickness of the saprolite ranges from less than 1 ft to 

several tens of feet. The Coastal Plain is underlain by a 

wedge of interlayered gravel, sand, silt, and clay 

deposited on a base of consolidated bedrock.

The Chickahominy River flows in a general 

southeasterly direction and discharges into the tidal 

James River. Chickahominy Reservoir is formed on the 

Chickahominy River by Walkers Dam (fig. 1). The 

river is tidal below the dam and generally nontidal 

above the dam. One of the purposes of the dam is to 

minimize the upstream flow of salty water. During 

spring tides (periods of extremely low and high tides 

caused by the alignment of the sun and the moon), 

however, salty water can flow upstream over the dam if 

streamflow is low.

The City of Newport News withdraws water 

from the reservoir just upstream from the dam. The 

drainage area above the dam is 301 mi2 . The 

characteristics of the stream channel and adjacent flood 

plain vary, depending on the hydrogeology of the 

physiographic province. In the Piedmont, the river 

generally has a single channel that is deeply incised 

into a narrow flood plain that limits the extent of 

adjoining wetlands. The average gradient in the stream 

channel decreases from about 0.01 in the extreme 

headwaters to 0.005 at the uppermost water-quality 

sample-collection station (CR60, fig. 1), to 0.002 

where the river enters the Coastal Plain. In the Coastal 

Plain, the flood plain widens to 1 to 2 mi and the width 

and depth of incision of the stream channel are highly 

variable. Although a deeply incised single channel is 

present along some reaches of the river, multiple 

shallow and wide channels spread across the broad 

flood plain along other reaches. The broad flood plain 

contributes to the presence of lowland wetlands. The 

channel slope generally is less than 0.001 along most 

stream reaches in the Coastal Plain.

Land use and cover in the uplands differ between 

the upper and lower parts of the basin. Most of the 

upper half of the basin (except for the extreme upper 

part) is primarily urbanized and consists of parts of the 

City of Richmond and the developed parts of Henrico 

and Hanover Counties. The lower half of the basin is 

primarily forested and contains some agriculture. For 

the entire basin in 1994, approximately 54 percent was 

forested (excluding forested wetlands), 16 percent was 

wetlands, 10 percent was residential, 7 percent was 

urban/developed, 9 percent was agriculture, 3 percent 

was grasslands, and 1 percent was old fields (Diane

Eckles, U.S. Department of Agriculture, Natural 

Resources and Conservation Service, written commun., 

1997).

The climate of the basin is characteristic of the 

humid Middle Atlantic states. Precipitation is plentiful 

(about 44 in/yr) and is fairly evenly distributed 

throughout the year (National Oceanic and 

Atmospheric Administration, 1996). The high summer 

and low winter air temperatures create seasonal 

changes in rates of evaporation and plant uptake of 

water (evapotranspiration); rates are highest in the 

summer and lowest in the winter. High rates of 

evapotranspiration in the summer remove large 

quantities of water from the soil and subsurface water, 

causing ground-water levels to decline and streamflow 

to decrease.

Acknowledgments

The author wishes to thank various individuals 

for involvement that was critical to the success of this 

study and completion of this report. Richard 

Mountcastle and Peter Daniel provided access to their 

property for local study components. Cody W. Reinitz, 

Karen J. Gregg, and Robert W. Jacobsen, who were 

employed by the USGS as a part of the cooperative 

program for students from Virginia Polytechnic and 

State University, assisted with data collection, data 

processing, and data presentation. Richard J. Ahlin, 

William V. Daniels, Jr., Karl M. Dydak, and Joel R. 

Guyer of the USGS Virginia District also collected 

data. Sherry Williams, Water Quality Manager for the 

City of Newport News Waterworks, and the rest of the 

laboratory staff analyzed samples for a variety of 

organic constituents. Robert B. Banks and Theodore B. 

Samsel III of the USGS Virginia District assisted in the 

preparation of illustrations. Technical content of this 

report was improved by reviews provided by Marcus C. 

Waldron (USGS, Northborough, Mass.) and William R. 

Green (USGS, Little Rock, Ark.). The readability of 

this report was significantly improved by the editing 

provided by Martha L. Erwin.

STUDY METHODS

The study consisted of field and laboratory 

studies. Field studies were designed to evaluate spatial 

and temporal variability in concentrations of DOC and 

DBP precursors in stream water and the contribution of

Study Methods 5
ground water to the organic content of stream water. 

Laboratory studies were conducted to evaluate (1) the 

contribution of stream-bed detritus to the DOC content 

of stream water and (2) the degradation of DOC in 

stream water.

Samples were analyzed for numerous analytes 

depending on the purpose of the sample. Analyses 

included the absorbance of light at 253.7 nm (UV254) 

and concentrations of major ions, stable isotopes 

(oxygen-18/oxygen-16 ratios ( 18O) and deuterium/ 

hydrogen ratios (D)), DOC, and total organic carbon 

(TOC). Samples also were analyzed for THM 

formation potential (THMFP), TOX formation 

potential (TOXFP), and haloacetic acid formation 

potential (HAAFP).

UV254 of samples was analyzed by the USGS 

laboratory in Richmond, Va., using a method described 

by the U.S. Environmental Protection Agency (1994). 

Absorbance is defined by the following equation:

A = logP0/P

where A is the absorbance, P0 is the power of the light 

beam after passing through de-ionized water, and P is 

the power of the light beam after passing through 

sample water (Skoog and West, 1963). Because 

cuvettes of different widths can be used, units of absorbance are reported as "per the width of sample cuvette 

through which the light beam passes." Units for absorbance in this report are "per centimeter" (cm1 ).

Concentrations of stable isotopes were analyzed 

by the USGS laboratory in Reston, Va., using a method 

described by Coplen and others (1991). Concentrations 

of major ions were analyzed by the USGS National 

Water Quality Laboratory in Arvada, Colo., using 

methods described in Fishman and Friedman (1989) 

and Fishman (1993). Concentrations of DOC, TOC, 

THMFP, TOXFP, and HAAFP were analyzed by the 

Waterworks Laboratory of the City of Newport News 

using methods described by the American Public 

Health Association (1995) and the U.S. Environmental 

Protection Agency (1992; 1994). THMFP is expressed 

as the sum of the concentrations of the trihalomethanes 

that are formed, in micrograms per liter. TOXFP is 

expressed as the concentration of chlorine that reacts 

with the DOC, in micrograms per liter of chloride (Cl). 

HAAFP is expressed as the concentration of the sum of 

the haloacetic acids that are formed, in micrograms per 

liter. The complexity and cost of many of the analyses

limited the number of samples that could be analyzed. 

Consequently, UV254 was used as a surrogate for the 

other organic analyses for many samples to provide a 

more comprehensive representation of the natural 

system than could otherwise be obtained. Only field 

parameters and UV254, therefore, were analyzed for 

many of the samples.

Results of analyses of stable isotopes, majors 

ions, and UV254 performed by USGS laboratories are 

published in White and others (1996; 1997; 1998; 

1999). UV254 and results of analyses of DOC, TOC, 

THMFP, TOXFP, and HAAFP performed by the 

Waterworks Laboratory of the City of Newport News 

are included in the appendix of this report.

Field Studies

Field studies consisted of stream-water and 

ground-water sampling. Stream-water samples were 

collected at a network of stations located throughout 

the basin. Ground-water samples were collected at 

wells and seeps in a sub-basin of the Chickahominy 

River.

Stream-Water Sampling

Stream-water samples were collected from a 

network of 27 stations located throughout the basin 

upstream from Walkers Dam (table 1, fig. 1). The 

network consisted of 6 main-stem Chickahominy River 

stations and 21 tributary stations. The main-stem 

stations are identified by "CR" followed by a number 

(CR60, for example). Main-stem stations were 

distributed from station CR60 in the headwaters to 

station CR02 about 6.5 mi upstream from Walkers 

Dam. No stations were located farther downstream than 

station CR02 because of backwater effects of 

Chickahominy Reservoir and tidal flow downstream of 

the dam. Station CR02 is a focus of this report because 

it is the main-stem station closest to the water-supply 

withdrawal point for the City of Newport News. 

Tributary stations were selected to represent the range 

of tributary characteristics that include drainage area, 

characteristics of valley incisement into the uplands 

(narrow, steeply sloped valleys or broad valley), land 

use, location of the sub-basin in the main basin, and the 

amount of wetlands. The stream length bordered by

6 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
Table 1. Characteristics of water-sample collection stations, Chickahominy River Basin, Virginia

[B, base-flow synoptic sample collection; Q, quarterly sample collection; S, stormflow sample collection; -, not available

Downstream 

sequence 

number

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

Station 

number

CR60

STR01

CR87

UPB01

HSW01

BDT01

BDC01

PWC01

BSC01

CRT01

CR40

CRT08

HGS01

CR45

TCT07

CRT07

WOS48

CNS01

WOS55

CRS01

CR70

CRT06

TRB06

SCT01

SNC01

CR02

DCR03

USGS station 

identification 

number

02042260

02042284

02042287

02042426

02042429

02042432

02042433

02042437

02042438

02042439

02042440

020424410

02042442

02042445

02042446

02042447

02042448

02042454

02042455

02042460

02042470

02042475

02042476

02042478

02042480

02042500

02042726

Station name

Chickahominy River at Rt. 624 nr. Farrington, Va.

Stony Run at Rt. 656 nr. Greenwood, Va.

Chickahominy River at US 301 nr. Atlee, Va.

Upham Brook at Wilkinson Road nr. Richmond, Va.

Horse Swamp at Richmond/Henrico Turnpike at Richmond, Va.

Beaverdam Creek Tributary nr. Mechanicsville, Va.

Beaverdam Creek at Rt. 156 nr. Mechanicsville, Va.

Powhite Creek at Rt. 156 at Cold Harbor nr. Meadows, Va.

Boatswain Creek nr. Highland Springs, Va.

Chickahominy River Tributary No. 1 at Rt. 613 nr. Richmond, Va.

Chickahominy River at Rt. 156 nr. Seven Pines, Va.

Chickahominy River Tributary No. 8 at Rt. 613 nr. Seven Pines, Va.

Higgins Swamp at Rt. 613 nr. White Oak Swamp, Va.

Chickahominy River at US 60 nr. White Oak Swamp, Va.

Chickahominy River Tributary to Tributary 7 at White Oak Rd. nr. 

White Oak Swamp, Va.

Chickahominy River Tributary 7 at White Oak Rd. nr. White Oak 

Swamp, Va.

White Oak Swamp at Beulah Road at Seven Pines, Va.

Canal Swamp at Portugee Rd. at Elko, Va.

White Oak Swamp at Rt. 156 at Elko, Va.

Crumps Swamp at US 60 nr. Roxbury, Va.

Chickahominy River at Rt 609 nr. Roxbury, Va.

Chickahominy River Tributary 6 at Rt 615 nr. Roxbury, Va.

Chickahominy River Tributary 6 at US 60 nr. Roxbury, Va.

Tributary to Schiminoe Creek at US 60 nr. Providence Forge, Va.

Schiminoe Creek at US 60 nr. Providence Forge, Va.

Chickahominy River at Rt. 61 8 nr. Providence Forge, Va.

Diascund Creek at Rt. 628 nr. New Kent, Va.

Stream

length 

bordered 

by wetland 

(percent)

48

54

45

31

0

0

39

-

53

71

45

82

74

49

0

5

0

82

74

83

55

0

0

51

87

56

55

Drainage 

area 

(square 

miles)

6.8

18.1

62.2

37.6

1.9

.1

11.3

2.9

0.9

2.1

149.3

1.0

2.1

171.3

.1

1.6

1.0

2.3

23.6

3.1

225.6

.4

.8

1.6

5.2

252

9.3

Sampling 

regime

B

B

B, Q, S

B

B

B

B

B

B

B

B, Q

B

B

B

B

B,Q

B

B,Q

B, Q,S

B

B,Q

B

B

B, Q, S

B

B, Q, S

B, Q, S

Study Methods 7
wetlands (fig. 1) was derived from the 1994 wetlands 

delineation by the U.S. Fish and Wildlife Service 

(Diane Eckles, written commun., 1997).

Samples were collected at different frequencies 

during both base-flow and stormflow periods at 

different stations depending on the objective of the 

sample collection. Samples were collected at all 

stations during several synoptic base-flow collection 

periods (stations identified by a "B" in table 1). 

Synoptic base-flow sample collection was intended to 

provide a detailed assessment of the spatial distribution 

of the organic content of stream water throughout the 

basin during base-flow periods. Samples also were 

collected at five stations during selected stormflow 

periods (stations identified by an "S" in table 1) to 

evaluate changes in the organic content of the stream 

water as a result of stormflow. Samples were not 

collected at all five stations during each stormflow 

sample-collection period. Samples also were collected 

approximately once a quarter at nine stations to 

evaluate temporal changes in the organic content of 

stream water (stations identified by a "Q" in table 1). 

These included four main-stem and five tributary 

stations. Although quarterly sampling was intended to 

occur during base-flow periods, some samples were 

collected toward the end of stormflow periods at mainstem stations. Samples collected during quarterly 

sampling generally were analyzed for a more 

comprehensive group of analytes than samples 

collected during the synoptic sample collection.

The five stations in the stormflow samplecollection network were equipped with continuous 

stage recorders to assist in distributing the collection of 

samples over the stormflow hydrograph. At stations not 

equipped with continuous stage recorders, a temporary 

reference point was established, and the depth to the 

water surface from this reference point was measured 

when samples were collected. This measurement was 

subtracted from an arbitrary datum of 100 ft, according 

to protocols of the Virginia District of the USGS for 

establishing temporary reference points.

Samples were collected with a weighted glass 

bottle by depth integration at the center of streamflow 

when possible. Where water was too shallow, sample 

bottles were dipped near the center of streamflow. 

Water at all sampling stations was analyzed for fieldmeasured properties (water temperature, dissolved 

oxygen concentration, specific conductance, and pH). 

In the laboratory, all samples were analyzed for 

UV254, and selected samples were analyzed for

concentrations of major ions (dissolved sodium, 

potassium, calcium, magnesium, chloride, fluoride, and 

sulfate), stable isotopes ( 18O and D), DOC, TOC, 

THMFP, TOXFP, and HAAFP. The analyses performed 

on a given sample varied depending on the reason the 

sample was collected and the workload of the 

laboratory that performed each analysis.

Samples were processed and preserved 

differently in the field depending on the intended 

analysis. Analyses for stable isotopes and for THMFP, 

TOXFP, and HAAFP used whole water samples that 

required no processing other than being poured into the 

sample bottle. Samples for analyses of stable isotopes 

were stored in clear-glass poly seal bottles with no head 

space. Samples for analyses of THMFP, TOXFP, and 

HAAFP were stored in separate amber-glass bottles 

with no head space and were chilled on ice. TOC 

analyses used whole-water samples stored in amberglass vials to which two drops of concentrated 

hydrochloric acid (HC1) were added; samples were 

stored on ice. Samples for analysis of DOC and UV254 

were filtered in the field by use of a 0.45-|im pore size, 

silver filter in a stainless-steel filter support. Filtered 

samples were stored in 60-mL, amber-glass vials and 

chilled on ice. Two drops of concentrated HC1 were 

added to each DOC sample; the UV254 samples 

received no additional treatment. Major ion samples 

were filtered in the field using a 0.45-Jim pore size, 

membrane capsule filter. Anion samples received no 

additional treatment and were stored in plastic bottles. 

Cation samples were stored in acid-rinsed plastic 

bottles to which 1 mL of concentrated nitric acid was 

added.

Ground-Water Sampling

Ground water provides a large part of the 

streamflow in the Chickahominy River Basin and is 

also a potential source of organic carbon to stream 

water. Consequently, samples of ground water were 

collected from wells and seeps in the basin of an 

unnamed creek that is a tributary to Schiminoe Creek 

(near station SCT01, fig. 1), a tributary to the 

Chickahominy River. Wells were constructed in 

clusters at different locations to determine the organic 

content of ground water at different locations within 

the ground-water flow system. Wells in each cluster 

were screened at different depths to identify any 

vertical differences in the organic content of the ground

8 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
water. Water was collected from seeps in the stream 

bank of the creek because the seeps are sources of 

ground-water discharge to the stream.

Station SCT01 is near the lower end of the basin 

in which ground-water samples were collected. This 

part of the basin was selected for ground-water 

sampling because it appeared to represent the two 

major types of water-table aquifers in the Coastal Plain 

part of the Chickahominy River Basin. An upland 

water-table aquifer borders the creek (typical of the 

stream incision in fig. 2A) downstream of a reach that 

is bordered by an alluvial water-table aquifer overlain 

by a several-hundred-foot-wide wetland flood plain 

(typical of the stream incision in fig. 2B). Although it is 

not typical to have an upland water-table aquifer 

adjacent to a stream downstream of an alluvial watertable aquifer, this system provided an opportunity to 

evaluate the difference in the organic content of the 

ground water derived from both types of water-table 

aquifers.

One cluster of wells (wells UN30A, UN30B, and 

UN30C) was installed in the water-table aquifer about 

50 ft from the creek where it is bordered by the upland 

water-table aquifer (fig. 3). A transect of wells also was 

constructed from the edge of the wetland flood plain 

across the flood plain overlying the alluvial water-table 

aquifer. Two wells at the edge of the flood plain (wells 

ULS-1 and ULD-1) were open to the upland watertable aquifer. Two wells in the middle of the flood plain 

(wells FPS and FPD) and one at the edge of the creek 

(well FP05) were open to the alluvial water-table 

aquifer. Wells were constructed of 2-in-diameter 

polyvinylchloride well casings and 1-ft-long screens.

Ground-water samples were collected after 

pumping water from the wells until field-measured 

properties stabilized. Because of the high clay content 

of parts of the water-table aquifer, several wells yielded 

water very slowly and were pumped dry. In these 

situations, the wells were allowed to refill with water 

that was then pumped for samples. Water was collected 

from seeps in the stream bed (SP01, SP02, and SP03) 

by placing plastic food-storage bags under the seep 

until the bag filled with sufficient water for analysis. 

Mini-piezometers were driven into the stream bed and 

pumped to collect ground water immediately before it 

discharged to the stream. Sufficient water could not be 

pumped from the mini-piezometers for analysis, 

however, because the stream bed had a high clay 

content and low permeability. Consequently, only water 

from seeps and wells was analyzed for organic carbon

content. Water from the wells and seeps was analyzed 

for field-measured properties (water temperature, 

specific conductance, and pH), UV254, and 

concentrations of major ions, stable isotopes, and 

DOC. Ground-water samples were processed in the 

same manner as the surface-water samples.

Isotope Analysis

The abundance of 18O and D, the heavy, stable 

isotopes of oxygen and hydrogen, was analyzed in 

stream water and ground water to determine the 

seasonal effects of ground-water discharge and 

evaporation on streamflow of the Chickahominy River 

Basin. 18O and D occur in the natural environment, 

including in the water molecule, wherever the more 

abundant lighter-weight isotopes ( 16O and H, 

respectively) are present (Gat and Gonfiantini, 1981; 

Coplen, 1993). The abundance of 18O and D in water 

varies on global and local scales; therefore, 

measurement of the abundance of 18O and D in water 

can be an important tool in evaluating hydrologic 

processes and pathways. This variability occurs 

because the heavy isotopes react chemically and 

physically in a different manner than the lighter weight 

isotopes. This difference in reaction results in 

fractionation that depletes or enriches their abundance 

in the source water. Evaporation and condensation are 

among the processes that fractionate 18O and D.

Because of the limited abundance of 18O and D, 

the ratios of 18O to 16O ( 18O/16O) and D to H (D/H) can 

be measured to an order of magnitude greater accuracy 

than actual concentrations (Coplen, 1993). To provide a 

common reference, ratios of the isotopic composition 

of samples typically are compared to those of a 

standard. Comparisons are expressed as delta (6) values 

in units of parts per thousand (per mil) as indicated by 

the following equation for 18O:

,^,^,. ,

( O/ O)sample

 

O/ O)standard

-1 x 1,000.

Values from oxygen and hydrogen isotope samples are 

reported relative to the Vienna Standard Mean Ocean 

Water (VSMOW). A negative 5 value indicates that the 

sample is isotopically depleted relative to the standard 

and is referred to as isotopically "light." This is typical 

of waters in the Chickahominy River Basin.

Study Methods 9
UPLAND WATER-TABkE AQUIFER 

(SAND)

CONFINING UNIT SILT AND CLAY)

SPRINGS

AND 

SEEPS UPLAND WATER-TABLE 

AQUIFER (SAND) UPLAND WATER-TABL 

AQUIFER (SAND)

CONFINING UNIT 

(SILT AND CLAY)

ALLUVIAL WATER-TABLE 

AQUIFER

NOT TO SCALE

EXPLANATION

- WATER FLOW PATH

Figure 2. Conceptualized stream and ground-water interaction for a stream partly incised 

through the upland water-table aquifer (A), and for a stream fully incised through the upland 

water-table aquifer and into the confining unit (B).

10 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
SP01

FP05

SCT01

EXPLANATION

SEEP LOCATION AND 

NUMBER

WELL LOCATION AND NUMBER

SURFACE-WATER QUALITY 

STATION LOCATION AND 

NUMBER

DIRECTION OF STREAMFLOW

NOT TO SCALE

Figure 3. General locations of the flood plain, uplands, seeps, wells, and the surface-water quality station in part of 

the watershed of the tributary to Schiminoe Creek, Chickahominy River Basin, Virginia.

Study Methods 11
The relation of 8 18O and 8D in precipitation is 

defined by the equation

18 8D = m8 O-d,

where m is the slope of the relation and d is the 

deuterium excess. Globally, the mean deuterium excess 

is +10 per mil (Craig, 1961). The line formed by this 

relation applied globally is called the "global meteoric 

water line." Because the deuterium excess differs by 

location, a different equation can be derived for local 

precipitation. If isotopes in precipitation that 

contributes to streamflow are not fractionated, the 

isotopic composition of stream water will coincide 

with that of the local meteoric water line. If a 

substantial part of the stream water evaporates, the 

fractionated isotopes will result in a relation having a 

slope less than 8, and typically ranging from 3 to 6 

(Coplen, 1993). In moderate climates such as that in 

the Chickahominy River Basin, evaporation typically is 

not a factor in the fractionation of isotopes in water 

except where large lakes or reservoirs provide a large 

surface area for evaporation (Gat and Gonfiantini, 

1981).

Laboratory Studies

Laboratory studies were conducted to evaluate 

(1) the potential contribution of stream-bed detritus to 

the DOC content of stream water and (2) the potential 

for degradation of DOC in stream water.

Stream-Bed Detritus

Stream-bed detritus consisting of leaves, small 

branches, and pieces of porous wood was collected 

from the tributary to Schiminoe Creek near station 

SCT01 (fig. 1). These materials were selected because 

they were the predominant detritus in the stream bed. 

The materials were washed with tap water followed by 

an organic-free, de-ionized water rinse to remove 

stream water containing DOC and to leach readily 

soluble organic carbon from the surface of the material. 

The samples were then air dried for weighing purposes. 

The branches and wood were broken into pieces that 

would fit into the clear-glass, 1-L bottles in which the

samples were incubated. Material was not broken up 

further to minimize exposure of surfaces not previously 

exposed to water in the stream. Three samples of each 

type of material were weighed and placed in separate 

bottles. Similar sizes of branches and wood were 

placed in each bottle to reduce the differences in the 

amount of exposed surface area in replicate samples. 

The amount of surface area per unit mass of material, 

however, clearly differed among the different types of 

material and likely differed among samples of the same 

material type. Each bottle was filled with organic-free, 

de-ionized water. Bottles were capped and incubated 

for 11 days in the laboratory at room temperature. 

Bottles were shaken once or twice a day.

Each bottle was shaken and uncapped, and 

approximately 5 mL of water were extracted with a 

syringe. Water samples were filtered through 0.45-|im 

pore size, glass-fiber syringe filters and analyzed for 

UV254. Samples were first analyzed as soon as 

possible after all bottles were filled and capped; this 

analysis provided a baseline reference for subsequent 

analyses. Samples were also analyzed at 4 hours and at 

1,4, 8, and 11 days.

Degradation of Dissolved Organic Carbon

DOC degradation studies were designed to 

evaluate the potential for DOC degradation in stream 

water and to determine if photodegradation is a 

significant factor in this process. Water was collected at 

station CNS01 (fig. 1) on October 22,1997, as a part of 

quarterly sample collection. This site was selected 

because it is on a tributary that was shown to have a 

high DOC content based on results of the field studies. 

To evaluate DOC degradation, water was treated and 

incubated in several ways (fig. 4). Part of the water was 

filtered and part remained unfiltered. Unfiltered water 

was used to represent stream water that, among other 

factors, contains particulate organic material and large 

populations of microbes that can decompose the 

organic material. Water was filtered to remove 

particulate organic material and a large part of the 

microbial population. Samples were filtered in the 

field, and both filtered and unfiltered samples were 

chilled to 4°C and stored until the start of the 

incubation period. A 0.45-jim pore size, membrane 

capsule filter was used rather than the 0.45-|nm pore 

size silver filter because a large quantity of water was

12 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
needed for these studies. Silver filters are easily 

plugged and could not pass the needed volume of 

stream water.

To minimize possible contamination of the 

sample by organic residue from the capsule filter, the 

filter was washed with approximately 4 L of organicfree water. Approximately 0.5 L of sample water was 

then passed through the filter. Six amber-glass, 1-L 

bottles and six clear-glass, 1-L bottles were then filled 

with filtered water. Amber-glass bottles were used to 

inhibit light penetration to sample water; clear-glass 

bottles were used to permit light penetration to sample 

water. Bottles were filled sequentially with water 

directly discharged from the filter. Similarly, six amberglass, 1-L bottles and six clear-glass, 1-L bottles were 

filled with unfiltered water.

Of the six bottles of each glass type containing 

filtered or unfiltered sample water, half were incubated 

at room temperature on a south-facing window sill to 

promote biological degradation and photodegradation 

of the DOC. The other half of the sample bottles were

incubated at 4°C in a refrigerator to minimize 

degradation. This regime provided triplicate samples of 

each combination of filtration, bottle type, and 

incubation method.

Periodically, 5 to 10 mL of sample was poured 

from each bottle into individual small beakers. Water 

from unfiltered samples was filtered through 0.45-jnm 

pore size, glass-fiber syringe filters to remove particles 

that would increase absorbance readings. A portion of 

each sample was poured into a quartz cuvette and 

analyzed for UV254. A subsample from one of the 

three bottles of each of the treatments also was 

analyzed for concentrations of DOC and THMFP at the 

beginning and end of the study. The degradation studies 

were continued for 83 days from October 22, 1997, 

through January 13, 1998.

RAW WATER

FILTERED

AMBER GLASS

in

QC

O uj

QC Q.

^ 

LU

Q 

111

I 

O

UNFILTERED

CLEAR GLASS AMBER GLASS

LLJ 

DC

§1

OuS

CCQ_^

LLJ

Q 

LU

I 

O

CLEAR GLASS

LU 

CC

OLU DC o_

S

LU

Q 

LU

I 

O

LU

DC

DC a.

s

UJ

Q 

LU

I 

O

Figure 4. Treatment of water samples to evaluate degradation of dissolved organic carbon.

Study Methods 13
BASIN HYDROLOGY

The hydrology of the Chickahominy River Basin 

affects water quality within the basin, including the 

organic carbon content of streams. Ground and surface 

water are hydraulically interconnected, and both, 

therefore, can be important transport pathways for 

organic carbon.

Surface Water

Streamflow was variable during the study period 

(table 2). Mean annual flow at station CR02 in water 

year 1995 was about 57 percent of the mean annual 

flow for the period of record. A record low flow of 

0.30 ft3/s for station CR02 was recorded in September 

1995. Mean annual flow in water year 1996 was near 

the long-term average. Mean annual flow in 1997 was 

about 16 percent greater than the long-term average. 

This, however, was a year of very contrasting flows. 

The monthly mean flow of 748 ft3/s in December 1996 

was about 2.6 times the monthly mean flow for the

period of record for December. In contrast the mean 

monthly flow for September 1997 was 0.17 ft3/s (less 

than 0.2 percent of the normal flow for the month). 

Another record low flow (0.06 ft3/s) was recorded on 

several days in September 1997. Water year 1998 was 

the wettest year of the study; the mean annual flow of 

380 ft3/s was 144 percent of the mean annual flow for 

the period of record. This year, however, was another 

year of extremely contrasting flow. The low flow of 

record was nearly repeated in October 1997 before 

flows increased to a peak mean monthly flow of 

1,198 ft3/s in February 1998. This was 2.8 times the 

mean monthly flow for February for the period of 

record. Streamflow again decreased to approximately 

15 percent or less of the mean monthly Streamflow in 

August and September 1998.

Streamflow in the Chickahominy River Basin 

consists of either stormflow or base flow. Stormflow 

consists of ground-water discharge and surface runoff, 

but is largely surface runoff; base flow is entirely 

ground-water discharge. During stormflow periods, 

Streamflow normally increases from base flow to a 

peak flow and then declines back to base flow. The

Table 2. Streamflow characteristics at station CR02 for the period of record and for each year of 

the study period, Chickahominy River Basin, Virginia (units are cubic feet per second) (White 

and others, 1996; 1997; 1998; 1999)

Month or flow category

October

November

December

January

February

March

April

May

June

July

August

September

Mean annual flow

Instantaneous peak flow

Instantaneous low flow

Water year

1942-1998

144

209

287

380

430

481

384

240

165

146

161

107

263

7,710

.06

1995

84.7

237

144

300

195

334

102

254

71.6

44.4

5.53

13.8

149

1,040

.30

1996

113

209

154

524

534

297

377

155

97.2

181

156

459'

270

2,230

7.7

1997

508

373

748

329

447

490

266

260

111

97.0

20.6

.17

304

1,450

.06

1998

24.9

287

150

643

1,198

1,055

561

350

169

157

15.2

16.3

380

2,880

.07

14 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
response time to attain peak flow, the size of the peak, 

and the relative contribution of surface runoff and 

ground-water discharge to stormflow are influenced by 

land use and cover, soil composition, and basin size, 

shape, and geomorphology (Focazio and Cooper, 

1995). Two of the most important aspects of land use 

and cover that affect stormflow characteristics are the 

amount of impervious area and the amount of wetland 

flood plains.

Typically, Streamflow responds rapidly to 

precipitation in small basins and in basins that have 

large percentages of impervious area, high slopes, or 

only small areas of wetland flood plains. Response to 

precipitation is slower in large basins and in basins that 

have little impervious area, low slopes, or extensive 

wetland flood plains. Thus, Streamflow responds more 

rapidly to precipitation in tributaries of the urbanized 

areas and headwaters than in downstream parts of the 

main stem of the Chickahominy River. In small 

tributaries, Streamflow can attain peak flow within a 

few hours and return to base flow a few hours later. In 

contrast, Streamflow typically requires 3 to 5 days after 

the precipitation to reach its peak at the farthest 

downstream main-stem station (CR02), and 10 to 14 

days to return to base flow.

Although the total runoff from a given stormflow 

event generally increases downstream with increasing 

drainage area, the peak flow in the Chickahominy 

River for a given storm can be greater upstream 

because the peak is attenuated as the water flows 

downstream and spreads over the broad wetland flood 

plain. For example, the peak flow at stations CR87 and 

CR02 for water year 1996 (from October 1, 1995, 

through September 30,1996) occurred during the same 

runoff event in January 1996. The peak flow at CR87 

was 3,070 ft3/s on January 20, but the peak flow 

downstream at CR02 on January 22 was only 

2,230 ft3/s (table 3).

During low, base-flow periods, the meandering 

nature of the Chickahominy River and the presence of 

multiple shallow stream channels results in sluggish 

flow and long traveltimes from the headwaters to the 

lower nontidal part of the basin. On the basis of average 

flow velocities measured throughout the basin during 

the August 1995 sample-collection period, the 

traveltime from the headwaters to station CR02 was 

estimated to be about 60 days. Because Streamflow 

velocity was insufficient to measure with a current 

meter at many points in the streams, average measured 

velocities likely are greater than average actual

Table 3. Streamflow characteristics at stations CR87, UPB01, and CR02 (Prugh and others, 1995; White and others, 

1997), Chickahominy River Basin, Virginia

9 o

[mi , square miles; ft /s, cubic feet per second; in/yr, inches per year; NR, no record]

Characteristic and units

^

Drainage area (mi )

Period of record

Mean annual flow for the period of record (ft3/s)

Mean annual runoff for the period of record (in/yr)

T

Mean annual flow for water year 1996 (ft /s)

Mean annual runoff for water year 1996 (in/yr)

Instantaneous peak flow for the period of record (ft /s)

Date of instantaneous peak flow for the period of record

Instantaneous peak flow for water year 1996 (fP/s)

Date of instantaneous peak flow for water year 1 996

Instantaneous low flow for the period of record (ft /s)

Date of instantaneous low flow for the period of record

CR87

62.2

Jan. 1990 to 

Oct. 1 997

56.4

12.32

62.8

13.74

4,220

March 5, 1993

3,070

Jan. 20, 1996

.00

Aug. 1-6, 1993, and Aug. 29

UPB01

37.6

Dec. 1989 to Oct. 

1994

39.4

13.88

NR

NR

2,410

Nov. 28, 1993

NR

NR

.21

lima OZ. Ida'3

CR02

252

Jan. 1942 to present

260

14.04

270

14.57

7,710

Aug. 15, 1955

2,230

Jan. 22, 1996

.06

Qant 19 14.1P 1QQ7

to Sept. 1, 1995

Basin Hydrology 15
velocities for the stream reaches represented by a given 

measurement. Consequently, the actual traveltime 

probably was substantially longer than the estimated 60 

days. The long traveltime and the shallow and 

meandering characteristics of much of the stream 

channel enhance the opportunity for degradation 

processes to decrease concentrations of DOC in the 

stream water.

The flow of water from a stream into adjacent 

alluvial sediments and back into the stream can 

significantly affect the chemistry of the stream water. 

The sediments through which infiltrating stream water 

flows are referred to as the hyporheic zone. Numerous 

studies have shown substantial effects of the exchange 

of water between the stream and the hyporheic zone on 

dissolved oxygen and DOC concentrations of stream 

water (Findlay, 1995). These studies generally have 

been conducted in mountain and headwater streams 

that flow through thick, permeable sand and gravel 

deposits (Bencala and others, 1984; Constanz, 1998; 

Harvey and Bencala, 1993). Harvey and Bencala 

(1993) indicate that pool and riffle sequences provide 

the head differences between the stream and the 

hyporheic zone that are needed for stream water to 

infiltrate into bed sediments and subsequently return to 

the stream. Because of the low gradient in the stream 

bed of the Chickahominy River, however, few pool and 

riffle sequences are present. Additionally, the alluvial 

bed sediments are composed of low permeability, finegrained sand, silt, and clay. Thus, exchange of water 

between the Chickahominy River and the hyporheic 

zone is probably limited.

Evaporation

Evaporation from a stream surface can result in a 

a substantial loss of water from the stream, even in the 

humid and temperate climate of Virginia. The shallow, 

wide, and meandering stream channel of the 

Chickahominy River makes it prone to evaporation 

during warm summer months.

The abundance of 18O and D in stream water of 

the Chickahominy River Basin, unlike that of most 

streams in moderate climates, indicates that 

evaporation of stream water is substantial in the basin 

(fig. 5A). A meteoric water line for the Chickahominy 

River Basin was developed from isotope data from 

stream samples collected during the cold-weather 

months (late November through April). This meteoric 

water line has a slope of 8 (making it parallel to the

global meteoric water line) and a deuterium excess of 

13.8 per mil VSMOW. During warm-weather months, 

the 18O and D relation deviates from the meteoric water 

line, having a slope of 5.1, a deuterium excess of 

-4.0 per mil VSMOW, and an R2 of 0.93 (fig. 5A). The 

slope of the warm-weather relation is consistent with 

the slope of relations that reflect isotopic enrichment 

from evaporation. Although Gat and Gonfiantini 

(1981) indicate that evaporation in moderate climates 

typically is not sufficient to fractionate isotopes, 

evaporation appears to be an important factor in the 

Chickahominy River Basin. The sluggish flow and 

shallow meandering channel that enhance evaporation 

would also enhance degradation of DOC by providing 

a large surface for exposure to sunlight and bacteria, as 

well as a long traveltime.

Ground Water

Ground-water discharge contributes a major part 

of the streamflow in the Chickahominy River Basin, 

and therefore, can substantially affect the quality of 

stream water. Ground-water discharge at station CR02 

averaged 10.60 in/yr, or 70 percent of the mean annual 

flow from 1970 through 1990 (Richardson, 1994). Of 

the total ground water discharged to the river during 

that period, 6.36 in. discharged in the winter, 2.32 in. in 

the summer, and the remainder in the spring and fall. 

These seasonal differences result from the high rates of 

evapotranspiration in the summer that reduce the 

amount of ground water discharged to the streams.

Ground water flows through two major types of 

aquifer systems in the Chickahominy River Basin. In 

the Piedmont, water flows through fractures in the 

bedrock and pore spaces in the saprolite. In the Coastal 

Plain, water flows through pore spaces in the sand and 

gravel aquifers. In both the Piedmont and Coastal Plain 

systems, ground water is recharged by precipitation 

that infiltrates through the soils and percolates to the 

water table. Water flows vertically and laterally 

through the aquifers and confining units to areas of low 

elevation, where it discharges to streams, ditches, 

springs, seeps, and ponds. Ground water also 

discharges through evapotranspiration, particularly in 

wetlands. Ground-water discharge contributes part of 

the streamflow during stormflow periods and all of the 

natural streamflow during base-flow periods. Because 

most of the basin lies within the Coastal Plain, the 

remaining discussion focuses on the Coastal Plain 

aquifer system.

16 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
-10

oc 

£ -20

£ -30

ILJLJ 

Q

-50

-60

1 I i i i i r

(A)

Chickahominy River Basin Meteoric Water Line 

Deuterium = 8.0 x Oxygen-18 + 13.8

Chickahominy River Basin

Evaporation Line 

Deuterium = 5.1 x Oxygen-18 - 4.0

Global Meteoric Water Line 

/ Deuterium = 8.0 x Oxygen-18 + 10

I_____I_____I_____I_____I_____I

-10

QC

LU -20

Q_

ffi

ID 

LU 

Q

LU 

Q

-40

-50

-60

I I I I I I l I

Chickahominy River Basin Meteoric Water Liney 

Deuterium = 8.0 x Oxygen-18 + 13.8

Chickahominy River Basin Evaporation Line 

Deuterium = 5.1 x Oxygen-18 - 4.0

J_____I I_____I_____I_____I

-9 -8 -7 -6 -5 -4 -3 -2 

DELTA OXYGEN-18, IN PER MIL

Figure 5. Relation of oxygen-18 and deuterium in streams showing the effects 

of evaporation (A) and in ground water (B), Chickahominy River Basin, Virginia.

Basin Hydrology 17
The Coastal Plain aquifer system consists of 

upper unconfined, or water-table, aquifers underlain by 

a confining unit and confined, or artesian, aquifers 

separated from one another by additional confining 

units (Meng and Harsh, 1988). Because surface waters 

are in better hydraulic connection with the water-table 

aquifers than with confined aquifers, the water-table 

aquifers have a more pronounced effect on streamflow 

and stream-water quality than the confined aquifers. 

Two types of water-table aquifers are present in the 

Chickahominy River Basin: (1) an upland aquifer and 

(2) alluvial aquifers. The organic content of the water 

discharged from each aquifer type differs because of 

differences in the characteristics of each type.

Upland sandy sediment (Daniels and Onuschak, 

1974) forms the upland water-table aquifer. On the 

basis of the aquifer delineation of Meng and Harsh 

(1988), the upland water-table aquifer consists of 

unconfined parts of the Yorktown-Eastover aquifer. 

This aquifer is partly incised by the upstream parts of 

tributaries to the Chickahominy River, creating a good 

hydraulic connection between the aquifer and the 

tributaries (fig. 2A). The upstream parts of the 

tributaries generally form narrow, V-shaped valleys, 

providing limited wetlands and little available organic 

material.

Alluvial water-table aquifers are present where 

the Chickahominy River and downstream parts of the 

tributaries have eroded and fully incised through the 

sand of the upland water-table aquifer and into the 

underlying clayey confining unit. Because the clayey 

sediment erodes less readily than the upland sandy 

sediment, the Chickahominy River and lower parts of 

the tributaries meander and erode wider and flatter 

valleys than upstream parts of the tributaries, forming 

broad wetland flood plains (fig. 2B). This erosion 

creates wide "depositional basins" in the clayey 

sediment into which the eroded sediments have been 

redeposited. The redeposited sediments consist of 

organic and poorly sorted fluvial sediment ranging 

from clay to gravel in size. On the basis of information 

in Daniels and Onuschak (1974) and data from several 

holes that were augered in the flood plain, the thickness 

of the sediments that form the alluvial aquifers is less 

than 10 ft. In general, these aquifers tend to be of low 

permeability because of the high silt and clay content. 

The alluvial water-table aquifers appear to be 

discontinuous along some tributaries. The wetlands and 

high organic content of the aquifer sediment provide a 

large source of organic material for the ground water.

The contact between the upland water-table 

aquifer and the underlying confining unit is above the 

floor of the valleys in many areas. In such areas, the 

upland water-table aquifer is not in direct hydraulic 

contact with the alluvial water-table aquifers (fig. 2B). 

Consequently, seeps and springs commonly discharge 

from the upland water-table aquifer along valley walls 

at the basal contact between the aquifer and the 

confining unit. Because the tributaries intercept much 

of the discharge from the upland water-table aquifer, 

fewer seeps and springs discharge along the valley 

walls of the Chickahominy River than its tributaries. 

Water discharged from the upland water-table aquifer 

flows across the flood plains and is a locally important 

source of water for many of the wetland plants and 

animals. As the water flows across the flood plains, it 

dissolves soluble organic carbon in the flood plain and 

either recharges the alluvial aquifers or flows into the 

nearby streams. Water in the alluvial aquifers 

discharges as evapotranspiration or flows toward the 

streams where it discharges as seeps along the stream 

banks or directly through the stream beds to the 

streams. Seeps discharge through sediment of relatively 

high permeability in the stream banks that overlie 

sediment of relatively low permeability. These seeps 

typically occur in lines along the contact between the 

sediments. Water also discharges through macropores 

that vary in size and are as large as several inches in 

diameter. Discharge from the seeps and macropores 

appears to be derived from both interflow (lateral flow 

through soil above the water table) and ground water 

because some seeps and macropores only flowed for a 

short time after precipitation while others flowed 

during extended dry periods. Flow velocities from the 

macropores can be substantial; fans of sand were 

deposited in the stream bank at the mouth of many of 

the macropores. The channels of the tributaries are 

incised as much as 3 to 5 ft into the alluvial sediments.

Because the flood plain of the Chickahominy 

River is broad and fairly flat, gradients in the water 

table generally are small, which limits the amount of 

ground water discharged directly to the river. In areas 

where multiple channels are present, ground water has 

greater opportunity to discharge to surface waters. 

Because of the extensive vegetated wetland flood plain, 

evapotranspiration is a major discharge pathway for 

ground water, and because of the low permeability of 

much of the alluvial sediment, discharge to the river is 

commonly through seeps in the stream banks.

18 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
The isotopic composition of ground water and 

surface water in the Chickahominy River Basin 

indicates that ground water is the predominant source 

of stream water during base-flow periods. Water in 

both the alluvial and upland water-table aquifers has a 

consistent 18O and D composition that plots on the 

meteoric water line at the point of intersection with the 

stream-water evaporation line for the Chickahominy 

River Basin (fig. 5B).

LIGHT ABSORBANCE AT 253.7 

NANOMETERS (UV254) AS A 

SURROGATE ANALYTE

UV254 can be used as a surrogate for 

concentrations of DOC, THMFP, TOXFP, and HAAFP 

if sufficiently strong relations can be identified between

the variables (Singer and others, 1981; Edzwald and 

others, 1985). Although specific UV254, or SUVA 

(UV254 divided by the concentration of DOC), 

commonly provides stronger relations than UV254 in 

many systems, SUVA was not strongly related to 

concentrations of the substances analyzed in the 

Chickahominy River Basin and is not used here.

Relations between UV254 and concentrations of 

DOC and THMFP generally were strong; relations 

between UV254 and TOXFP were not as strong 

(table 4). Relations varied depending on the samplecollection period. Relations between UV254 and 

HAAFP were weak and are not summarized in table 4 

because HAAFP analyses were too few during most 

sample-collection periods to summarize. Relations 

'' between UV254 and concentrations of DOC, THMFP, 

and TOXFP are presented individually for each baseflow and stormflow collection period having sufficient

Table 4. Statistical relations between light absorbance at 253.7 nanometers and concentrations of dissolved organic 

carbon (DOC), trihalomethane formation potential (THMFP), and total organic halide formation potential (TOXFP) for 

surface-water samples, Chickahominy River Basin, Virginia

[R2 , coefficient of determination; N, sample size, values are for DOC, THMFP, and TOXFP; -, no value]

Sample-collection period

DOC THMFP TOXFP

All sample-collection periods

All sample-collection periods (N=239, 214, 96) 0.67 0.0000 0.67 0.0000 0.70 0.0000

Base-flow periods

All base-flow periods (N=156, 131, 52)

August 1995 (N=23, 23, 0)

March 1996 (N=22, 22, 22)

November 1996 (N=8, 9, 0)

December 1996 (N=25, 25, 0)

January 1997 (N=9, 7, 8)

April 1997(N=9,7,6)

May 1997 (N= 19, 16,0)

October 1997 (N=7, 5,0)

January 1998 (N=l 8, 14, 18)

.71

.79

.91

.91

.94

.90

.91

.95

.70

.68

.0000

.0000

.0000

.0003

.0000

.0001

.0001

.0000

.0192

.0000

.67

.77

.94

.95

.97

.91

.88

.93

.62

.49

.0000

.0000

.0000

.0000

.0000

.0008

.0018

.0000

.1139

.0054

.54

-

.84

-

-

.49

.42

-

-

.57

.0000

-

.0000

-

-

.0540

.1637

-

-

.0003

Stormflow periods

All stormflow periods (N=80, 80, 40)

August 1996 (N=l 6, 16, 11)

October 1996 (N=23, 22, 0)

November 1997 (N=22, 22, 13)

February 1998 (N= 19, 20, 16)

.48

.66

.58

.58

.91

.0000

.0001

.0000

.0000

.0000

.60

.12

.50

.60

.75

.0000

.1906

.0002

.0000

.0000

.68

.51

-

.08

.74

.0000

.0136

-

.3568

.0000

Light Absorbance at 253.7 Nanometers as a Surrogate Analyte 19
data for analysis. Relations are also presented for all 

base-flow periods collectively, all stormflow periods 

collectively, and all sample-collection periods 

collectively.

UV254 appears to be an effective surrogate for 

DOC concentrations because relations between UV254 

and DOC concentrations for individual samplecollection periods and for all data analyzed collectively 

generally were statistically significant (p<0.05) and 

strong (based on coefficient of determination (R2) 

values) (table 4). The p values were 0.0192 or less for 

all sample-collection periods evaluated individually or 

collectively (table 4). The R2 values for relations for 

individual sample-collection periods ranged from 0.58 

(p = 0.0000) for the October 1996 and November 1997 

stormflow periods (table 4; fig. 6A) to 0.95 

(p = 0.0000) for the May 1997 base-flow period 

(table 4; fig. 6B). In general, UV254 and DOC 

concentrations were more closely related for individual 

sample-collection periods, particularly the base-flow 

periods, than for all sample-collection periods 

combined (R2 = 0.67; p = 0.0000) (table 4; fig. 6C). 

The R2 values for six of the nine base-flow periods 

were equal to, or greater than, 0.90. The R2 values for 

the individual stormflow periods (0.58 to 0.91) 

generally were less than those of individual base-flow 

periods. The R2 values for the individual samplecollection periods probably were higher than for the 

data evaluated collectively because the relation 

between UV254 and DOC concentrations likely 

changed seasonally and under different hydrologic 

conditions.

Similarly, UV254 appears to be an effective 

surrogate for THMFP concentrations because relations 

between UV254 and THMFP concentrations for 

individual sample-collection periods and for data 

evaluated collectively generally were strong and 

statistically significant (table 4). The p values for 11 of 

13 sample-collection periods and for collectively 

analyzed data were less than 0.01. The p values were 

greater than 0.1 for the October 1997 base-flow period 

(p = 0.1139) and the August 1996 storm-flow period 

(p = 0.1906). The R2 values for the relation between 

UV254 and THMFP concentrations ranged from 0.12 

for the August 1996 stormflow sample-collection 

period (table 4; fig. 7A) to 0.97 for the December 1996 

base-flow sample-collection period (table 4; fig. 7B). 

In general, UV254 and THMFP concentrations were 

more closely related for individual sample-collection 

periods, particularly the base-flow periods, than for all 

sample-collection periods combined (R2 = 0.67;

p = 0.0000) (table 4; fig. 7C). The R2 values for five of 

the nine base-flow periods were greater than 0.90. The 

R2 values for the individual stormflow periods (0.12 to 

0.75) generally were less than those of individual baseflow periods. The low R2 values and the high p value 

for the August 1996 storm-flow period indicate the lack 

of a significant relation at that time. As with DOC 

concentrations, the R2 values for the individual samplecollection periods probably were higher than the R2 

values for the data evaluated collectively because the 

relation between UV254 and THMFP concentrations 

likely changed seasonally and under different 

hydrologic conditions.

Based on the statistical significance and the 

strength of fit of relations between UV254 and TOXFP 

concentrations, UV254 may not be an effective 

surrogate for TOXFP concentrations during certain 

sample-collection periods, but is an effective surrogate 

for all sample-collection periods combined. The p 

values of only three of seven periods were less than 

0.01 and four were less than 0.05. The R2 values of the 

relation between UV254 and concentrations of TOXFP 

ranged from 0.08 (p = 0.3568) (table 4; fig. 8A) for the 

November 1997 stormflow sample-collection period to 

0.84 (p = 0.0000) for the March 1996 base-flow 

sample-collection period (table 4; fig. 8B). The R2 

value was 0.70 (p = 0.0000) for all sample-collection 

periods combined (table 4; fig. 8C). The R2 values for 

all individual sample-collection periods except the 

March 1996 base-flow and the February 1998 

stormflow period were less than the R2 values for all 

sample-collection periods combined.

Based on the statistical significance and the 

strength of fit of relations between UV254 and HAAFP 

concentrations, UV254 was not an effective surrogate 

for HAAFP. The R2 of the relation between UV254 and 

concentrations of HAAFP was only 0.16 for all data 

although the p value was 0.0000 (fig. 9).

Based on the statistical significance and strength 

of the relations between UV254 and concentrations of 

DOC, THMFP, and TOXFP, the use of UV254 

generally is an effective surrogate for their 

concentrations. Because of the significance and 

strength of these relations, the following discussions 

focuses on UV254 results.

20 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
15

10

CC 

LJJ

b o

£ 15 

Q.

CC 

(D

^ 10

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DC 

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15

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y = 4.0 + 14.9x 

R2 = 0.58

x BASE-FLOW SAMPLE

(B)

y = 0.49 + 25.5x 

R2 = 0.95

STORMFLOW SAMPLE

(C)

y = 3.4 + 16.7x 

R2 = 0.67

XK,

XX «

x BASE-FLOW SAMPLE 

 STORMFLOW SAMPLE

0 0.2 0.4 0.6 0.8 1.0 1.2 

LIGHT ABSORBANCE AT 253.7 NANOMETERS, IN PER CENTIMETER

Figure 6. Relation of light absorbance at 253.7 nanometers and dissolved organic 

carbon concentrations for October 1996 (A), May 1997 (B), and all data (C), 

Chickahominy River Basin, Virginia.

Light Absorbance at 253.7 Nanometers as a Surrogate Analyte 21
1,500

1,000

500

DC 

LLJ

cc

HI

(A)

y = 625 + 580x 

R2 = 0.12

x BASE-FLOW SAMPLE

< 1,500

CC

(D

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CC

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LU

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500

= 130 + 1,400x

(C)

x BASE-FLOW SAMPLE 

 STORMFLOW SAMPLE

0 0.2 0.4 0.6 0.8 1.0 1.2 

LIGHT ABSORBANCE AT 253.7 NANOMETERS, IN PER CENTIMETER

Figure 7. Relation of light absorbance at 253.7 nanometers and trihalomethane formation 

potential concentrations for August 1996 (A), December 1996 (B), and all data (C), 

Chickahominy River Basin, Virginia.

22 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
3,000

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DC

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LU

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LU

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CD 2,500

O

DC

O

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p 1,500

z

LU

1,000

(A)

x x y = 2,600x 

R2 = 0.08

BASE-FLOW SAMPLE

500

D_

Z

o

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DC

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111

§ 6,000

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DC 

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= 110 + 4,220x 

R2 = 0.84

STORMFLOW SAMPLE

(C)

y = 205 + 5,800x 

R2 = 0.70

BASE-FLOW SAMPLE 

STORMFLOW SAMPLE

0 0.2 0.4 0.6 0.8 1.0 1.2 

LIGHT ABSORBANCE AT 253.7 NANOMETERS, IN PER CENTIMETER

Figure 8. Relation of light absorbance at 253.7 nanometers and total organic halide 

formation potential concentrations for November 1997 (A), March 1996 (B), and all data (C), 

Chickahominy River Basin, Virginia.

Light Absorbance at 253.7 Nanometers as a Surrogate Analyte 23
O rLLJ

P<°- 

LU p 

O ^

li

2,000

1,800

1,600

1,400

1,200

1,000

800

600

400

200

0

y = 490 + 650x 

R2=0.16

0 0.2 0.4 0.6 0.8 1 1.2 

LIGHT ABSORBANCE AT 253.7 NANOMETERS, IN PER CENTIMETER

Figure 9. Relation of light absorbance at 253.7 nanometers and haloacetic acid formation 

potential concentrations for all data, Chickahominy River Basin, Virginia.

DISSOLVED ORGANIC CARBON (DOC) 

AND DISINFECTION BY-PRODUCT (DBP) 

PRECURSORS

The DOC content of streams of the 

Chickahominy River Basin varies spatially and 

temporally depending on the sources of organic carbon 

in the basin, transport pathways to the river, seasonal 

variability in climate and hydrologic conditions, and 

the hydrologic response to storm events. The DOC 

content of the streams also is influenced by instream 

processes such as the leaching of organic material from 

stream-bed detritus and biological and 

photodegradation of the DOC. Results of laboratory 

studies show the role of stream-bed detritus as a source 

of DOC in stream water and the role of degradation in 

reducing DOC concentrations in stream water. Results 

of analyses of surface-water samples from the 

Chickahominy River Basin show spatial and temporal 

variability in concentrations of DOC and DBP 

precursors in the river. Emphasis is placed on station 

CR02, the farthest downstream sampling point and the 

point nearest to the City of Newport News water intake. 

Results of analyses of samples from tributary streams 

and from ground-water sources show the importance of 

these water and DOC transport pathways.

Contributions of Stream-Bed Detritus to 

DOC in Stream Water

In the laboratory studies of stream-bed detritus, 

changes in UV254 varied considerably among replicate 

samples of each material type, as well as among 

material types (fig. 10). UV254 increased at the 

greatest rate in all samples in the first 4 hours (0.17 

days) of incubation. A "tea color" common to waters 

having a high humic-substance content also developed 

within the first 4 hours of incubation. Although the 

intensity of the tea color and the UV254 generally 

increased with time, the rate of increase in UV254 

generally decreased with time. The UV254 was 0.041 

to 0.447 cm' 1 after the first four hours (fig. 10), a range 

commonly observed in stream waters of the 

Chickahominy River Basin (fig 6C). At the end of the 

first day, the highest three UV254 values (0.773 to 

0.991 cm- 1 ) were greater than those commonly 

observed in stream water of the basin. By the fourth 

day, UV254 ranged from 0.491 to 2.78 cm' 1 in water 

from the samples incubated with branches, 1.53 to 

2.3 cm4 in water from the samples incubated with 

leaves, and 0.106 to 0.606 cnr 1 in water from samples 

incubated with porous wood. Values for the leaf and 

small branch samples were greater than those 

commonly observed in stream water of the 

Chickahominy River Basin.

24 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
DC 

LJJ

LU

LJJ 

O

DC 

LJJ 

Q_

CO 

DC 

LJJ

LJJ 

S 

O 

Z 

< 

Z 

hcd

LO 

CM

LJJ 

O

Z 

<

m DC O

CO

m

O

SMALL BRANCHES

LEAVES

POROUS WOOD

Figure 10. Change in light absorbance at 253.7 nanometers of organic-carbon-free 

water incubated with small branches, leaves, and porous wood.

Dissolved Organic Carbon and Disinfection By-Product Precursors 25
The rapid development of the tea color and the 

rapid increase in UV254 in these laboratory studies 

indicate that leaves, small branches, and wood in 

stream beds likely are a substantial source of UV254, 

DOC, and THMFP in stream water. In order to equate 

values .of UV254 and the contributions of stream-bed 

detritus to the organic content of the stream water, field 

studies must determine the amount of organic material 

in the stream bed and relate the amount of organic 

material to the amount of streamflow.

Degradation of DOC in Stream Water

Results of the degradation studies present 

UV254 as the decimal fraction of the original UV254 

of sample in each bottle. Based on the UV254 of 

samples incubated at room temperature, degradation 

appears to reduce the DOC content of stream water 

(table 5; fig. 11). UV254 decreased 8 to 20 percent in 

both filtered and unfiltered samples incubated at room 

temperature in amber glass and 29 to 41 percent in 

filtered samples incubated at room temperature in clear 

glass. The greatest decrease in UV254 (45 to 58 

percent) was in unfiltered samples incubated at room 

temperature in clear glass. Because UV254 decreased 

considerably more in samples in clear glass than in

amber glass, a large part of the decrease in UV254 

appears to result from photodegradation or photoenhancement of the degradation.

The role of biodegradation, however, is not clear. 

The decrease in UV254 in amber glass was similar in 

the filtered samples to that in the unfiltered samples. 

The decrease in UV254 in clear glass, however, was 

less in the filtered samples than in the unfiltered 

samples. These results indicate that biodegradation 

is likely an important process that may, in part, be 

mediated by sunlight.

In filtered samples incubated at room 

temperature, concentrations of DOC and THMFP 

decreased proportionally similar to UV254 (table 5). 

Thus, the decrease in UV254 of filtered samples during 

the study probably is representative of changes in 

concentrations of DOC and THMFP.

The UV254 of five of the six samples filtered in 

the field and chilled remained at least 99 percent of the 

original value over the 83 days of the study (table 5; 

fig. 11). UV254 of the sixth sample remained at least 

99 percent of the original value to between 21 and 33 

days of the study and remained at least 94 percent of 

the original value through the 57th day of the study. 

Similarly, the UV254 of the unfiltered and chilled 

samples remained 91 percent of the original value or

Table 5. Fraction of original light absorbance at 253.7 nanometers (UV254) and concentrations of organic 

carbon (dissolved for filtered samples and total for unfiltered samples) and trihalomethane formation potential 

(THMFP) remaining at the end of the laboratory study of the degradation of organic carbon in water collected 

October 1997 from station CNS01, Chickahominy River Basin, Virginia

[cm , per centimeter; mg/L milligrams per liter; (j.g/1, micrograms per liter; -, no data]

Filtered samples

Determination Chilled

1 2 3

Room temperature

1 23

Unfiltered samples

Chilled

1 2 3

Room temperature

1 2 3

Amber glass

UV254(cm-') 0.99 0.99 0.99

Organic carbon 

(mg/L) ' yci

THMFP (|j.g/L) .80

0.80 0.92 0.82

.78

.71

0.99 0.98 0.95

.96

.90 - -

0.86

.95

.77

0.84 0.83

-

-

Clear glass

UV254(cm-') .91 1.00 .99

Organic carbon - - .89

THMFP - - .77

.61 .59 .71

.76

.75

1.00 .91 .95

.86

.76 -

.55

.91

.66

.49 .42

-

-

26 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
C/) 

DC 

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CO 

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03

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1.2 

1.0 

0.8 

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FILTERED UNFILTERED 

CHILLED IN AMBER GLASS

I I I I I I I I i i i i

ROOM TEMPERATURE IN AMBER GLASS

1 I I I I I I I

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CHILLED IN CLEAR GLASS

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ROOM TEMPERATURE IN CLEAR GLASS

i i i

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10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90

Figure 11. Changes in light absorbance at 253.7 nanometers of replicate samples.

Dissolved Organic Carbon and Disinfection By-Product Precursors 27
greater through the 83rd day of the study; the UV254 

of two of six samples remained at least 99 percent of 

the original value.

These results indicate that degradation of DOC 

and DBF precursors in stream water of the 

Chickahominy River Basin at least partly 

counterbalances input from sources such as stream-bed 

detritus. Instream degradation is likely to be greatest 

during summer base flows when stream-water 

temperatures are elevated, instream traveltime is high, 

and the duration and intensity of sunlight are greatest.

Temporal and Spatial Variability in 

Concentrations of DOC and DBF 

Precursors in Stream Water

The temporal and spatial variability in 

concentrations of DOC and DBF precursors varies 

depending on streamflow conditions. This variability 

results from changes in sources of organic carbon, in 

transport pathways, and in transformation processes 

that result from hydrologic changes.

Base-Flow Periods

During base-flow periods, UV254 and 

concentrations of DOC, THMFP, TOXFP, and HAAFP 

generally decreased along the main stem of the 

Chickahominy River from station CR60 to CR40 and 

stabilized between station CR40 and CR02 at the 

downstream end of the nontidal part of the river (fig. 

12). This is somewhat surprising in that wetlands are 

more predominant in the middle and lower parts of the 

Chickahominy River Basin and were expected to be a 

substantial source of organic material. Thurman (1985) 

reports that rivers draining swamps and wetlands have 

the largest DOC concentrations. UV254 and the 

organic content of the river decreased downstream 

from the headwaters during both cold-weather months 

(November through March) and warm-weather months 

(April through October).

During each of these seasons, the organic content 

of the river increased slightly downstream from stations 

CR45 and CR70 to station CR02. This increase could 

have resulted in part from residual stormflow in the 

lower part of the basin. Because streamflow at station 

CR02 can take two weeks or more to return to baseflow conditions from a stormflow period, "base-flow" 

samples commonly reflect remnants of stormflow

periods in the lower nontidal part of the basin. 

Although streamflow declines after peak flow in the 

lower nontidal part of the basin, the organic content of 

the water can be elevated as a result of the previous 

storm. Samples collected at station CR02, therefore, 

probably seldom reflect true base-flow conditions.

Synoptic sampling of tributary streams during 

base-flow conditions show that the downstream decline 

in the organic content of the Chickahominy River 

between sampling station CR60 and CR40 is in part 

due to dilution from the lower organic content of water 

discharged from the tributaries (fig. 13). The UV254 

and concentrations of DOC of the tributaries were in all 

cases less than the concentrations of the main-stem 

Chickahominy River. Below station CR40, UV254 and 

DOC concentrations of the tributaries were also 

generally less than the main-stem Chickahominy River, 

yet concentrations at downstream sampling station 

CR45, CR70, and CR02 do not show similar declines. 

This indicates the presence of an additional source of 

organic carbon in or discharging to the lower 

Chickahominy River that counterbalances the effects of 

dilution from the lower tributaries. The most likely 

sources of DOC in the lower Chickahominy River 

during base-flow periods are ground-water discharge 

from the alluvial aquifer, leachate from stream-bed 

detritus, and residual effects from previous storms.

During base-flow periods, THMFP and TOXFP 

concentrations varied spatially in a manner similar to 

UV254 and DOC concentrations. THMFP 

concentrations exceeded the MCL for THMs in all 

samples collected during base-flow periods at station 

CR02 and at all other stations except for two samples 

collected at station CRT06. HAAFP concentrations 

exceed the MCL during base-flow periods for all 

samples.

Ground-Water Sources

Ground-water flow is an important transport 

pathway for organic carbon in the Chickahominy River 

Basin. Ground water discharge averaged 70 percent of 

the annual streamflow in the Chickahominy River from 

1970 through 1990 (Richardson, 1994) and constitutes 

all of the base flow and part of the stormflow of the 

basin. The organic content of ground water in the 

Schiminoe Creek tributary was elevated, indicating that 

ground water can be a substantial source of DOC and 

DBF precursors.

28 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
0.8

ggffi 0.6

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STATION NUMBER 

9

DC DC 

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j_____i_____i_____i

March 1996

fee?

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0 5 10 15 20 25 30 35

DISTANCE DOWNSTREAM FROM

HEADWATERS, IN MILES

EXPLANATION

n MAXIMUM

MEDIAN

u MINIMUM

STATION NUMBER

OC DC 

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1,000

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^ January 1 996 

January 1997^^. ^.yl _ t

Drinking-water maximum contaminant level 

(60 micrograms per liter)

0 5 10 15 20 25 30 35

DISTANCE DOWNSTREAM FROM

HEADWATERS, IN MILES

Figure 12. Downstream changes in light absorbance at 253.7 nanometers in cold-weather months (November through 

March) (A), light absorbance at 253.7 nanometers in warm-weather months (April through October) (B), concentrations of 

dissolved organic carbon (C), concentrations of trihalomethane formation potential (D), concentrations of total organic halide 

formation potential (E), and concentrations of haloacetic acid formation potential (F) at base flow, Chickahominy River 

Basin, Virginia.

Dissolved Organic Carbon and Disinfection By-Product Precursors 29
CD LU

CM

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(E)

_

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/ level (60 micrograms per liter)

-

/

/ . « t

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i i i i i

 > c ^ n HIT on oc o

EXPLANATION

CR60 STATION NUMBER FOR MAIN-STEM

SAMPLING STATION

TRIBUTARY MAIN-STEM

STATION STATION

n MAXIMUM n MAXIMUM

-

 MEDIAN MEDIAN

n U MINIMUM LI MINIMUM 5 10 15 20 25 30

DOWNSTREAM SEQUENCE NUMBER

Figure 13. Light absorbance at 253.7 nanometers (A) and concentrations of dissolved organic carbon (B), trihalomethane 

formation potential (C), total organic halide formation potential (D), and haloacetic acid formation potential (E) at the tributary 

(unidentified) and main-stem (identified by station number and shading) stations in downstream sequence number (Table 1) 

during synoptic sample-collection periods, Chickahominy River Basin, Virginia.

30 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
In the Schiminoe Creek Watershed, the organic 

content of the ground water from the upland watertable aquifer was less than that from the alluvial watertable aquifer. UV254 ranged from 0.017 to 0.209 cm- 1 

and DOC ranged from 0.60 to 1.4 mg/L in water from 

wells open to the upland water-table aquifer (table 6). 

UV254 ranged from 0.102 to 2.450 cm-' and DOC 

ranged from 2.5 to 5.2 mg/L in water from wells open 

to the alluvial water-table aquifer. UV254 and DOC of 

water discharged from seeps ranged from 0.131 to 

0.668 cnr 1 and 4.1 to 9.5 mg/L, respectively.

The concentration of DOC of water discharging 

from the alluvial water-table aquifer through seeps in 

the stream bank was almost twice that of ground water 

from wells open to the same aquifer. The UV254 of 

water from the wells, however, was about twice that of 

water discharging through seeps. This difference in the 

characteristics of DOC of water discharging through 

seeps from that in ground water from the wells likely 

results from changes as the ground water flows through 

the aquifer to areas of discharge.

The organic content of the ground water only 

partly accounts for the organic content of stream water 

based on a comparison of the ground water from the 

alluvial aquifer and water in the tributary to Schiminoe 

Creek (station SCT01). Although the median and 

maximum UV254 values of water from the alluvial 

water-table aquifer are greater than median and 

maximum values from station SCT01, median and 

maximum values of the DOC of water from the alluvial 

water-table aquifer are less than equivalent values from 

station SCT01. This likely results from the different 

characteristics of the DOC of the ground water 

compared to that of the surface water: DOC derived 

from the ground water appears to have a greater UV254 

for an equivalent DOC than that of the surface water. 

This difference may in part result from the contribution 

of DOC to stream water by stream-bed detritus.

Organic carbon in ground-water discharge from 

the.alluvial aquifer is derived from two sources: 

(1) organic material in the aquifer sediment that was 

derived at the time the sediment was deposited, and

Table 6. Summary of light absorbance at 253.7 nanometers (UV254) and concentrations of dissolved organic 

carbon (DOC) of ground water from the upland water-table aquifer, ground water from wells and seeps in the 

alluvial water-table aquifer, and stream water during base-flow periods at stations SCT01 and CR02, 

Chickahominy River Basin, Virginia

Determination Minimum Maximum Median

Number 

of 

samples

Upland Water-Table Aquifer

UV254 (per centimeter) 

DOC (milligrams per liter)

0.017 0.209 

.60 1 .4

0.040 

1.3

7 

5

Wells in the Alluvial Water-Table Aquifer

UV254 (per centimeter) 

DOC (milligrams per liter)

.102 2.450 

2.5 5.2

.600 

3.2

10 

6

Seeps in the Alluvial Water-Table Aquifer

UV254 (per centimeter) 

DOC (milligrams per liter)

.131 .668 

4.1 9.5

.257 

5.6

4 

4

Schiminoe Creek Tributary (SCT01)

UV254 (per centimeter) 

DOC (milligrams per liter)

.148 .535 

5.4 15

.270 

7.9

15 

11

CR02

UV254 (per centimeter) 

DOC (milligrams per liter)

.171 .616 

6.7 13

.284 

9.1

17 

12

Dissolved Organic Carbon and Disinfection By-Product Precursors 31
(2) soluble organic carbon leached from the organic 

litter by infiltrating water. Because much of the alluvial 

aquifer consists of silt and clay deposited in low-energy 

environments of the flood plains where organic 

material had also accumulated, the sediment contains 

abundant organic carbon. As this organic carbon 

decomposes, the soluble organic carbon can leach into 

the ground water and be transported to streams. 

Although sorption of DOC to clay typically decreases 

the DOC of infiltrating water (Thurman, 1985), the 

natural abundance of organic material in alluvial 

sediment can limit the sorption of DOC in infiltrating 

water.

Precipitation and decomposition of the organic 

litter contribute DOC to ground water. The flood-plain 

wetlands are seasonally inundated and saturated; 

consequently, several months can pass without 

inundation of these wetlands. These periods typically 

occur during warm-weather months when rates of 

decomposition of the organic litter and 

evapotranspiration are high. Therefore, large amounts 

of soluble organic carbon can form and remain in the 

organic litter as the litter decomposes. Because the 

initial precipitation infiltrates through the organic litter 

and into the unsaturated soil rather than running off, the 

first transport pathway for soluble organic carbon is 

from the organic litter to the water table. Precipitation 

often is not sufficient to produce substantial runoff or to 

cause infiltrating water to reach the water table; 

therefore, a reservoir of soluble organic carbon can be 

created in the unsaturated soil. Even when precipitation 

is sufficient to produce surface runoff, the initial part of 

that precipitation will also infiltrate through the organic 

litter and into the unsaturated soil, adding to the 

reservoir of soluble organic carbon. This reservoir of 

soluble organic carbon will not be available for 

transport across the flood plain in surface runoff. When 

sufficient water infiltrates to recharge the ground water, 

DOC in the unsaturated zone will be transported to the 

ground water and can then be transported to the 

streams. Because streamflow during base-flow 

conditions is entirely ground-water discharge, ground 

water can, therefore, be a substantial source of DOC to 

the streams.

DOC also can be transported with water that 

flows above the water table through macropores and 

through relatively high permeability soils that overlie 

relatively low permeability soils. This flow, commonly

referred to as interflow, occurs mostly during and 

immediately after significant storms and can affect the 

timing and the amount of DOC transported to streams.

Stormflow Periods

Stormflow response was similar seasonally and 

among sites in that the peak in the organic content of 

stream water generally occurred at, or after, peak 

streamflow (table 7, appendix 1). UV254 increased by 

16 to almost 100 percent from base flow to after peak 

flow at station CR02; the greatest increase was by more 

than 200 percent at station CR87 in November 1997 

(appendix). Increases in concentrations of DOC, 

THMFP, and TOXFP varied among Stormflow periods 

and stations but generally ranged from 25 to 75 

percent.

Two Stormflow sample-collection periods (July 

16-September 17, 1997, and February 16-March 13, 

1998) for station CR02 exemplify the Stormflow 

response. These two collection periods were selected 

because (1) one was in the middle of a summer baseflow period, (2) one was in the middle of a winter highflow period, and (3) both are represented by samples 

collected before, during, and after the Stormflow 

periods. These two Stormflow collection periods 

occurred in the middle of the most extreme hydrologic 

conditions of the study.

Initially, Stormflow sample collection was 

designed to represent Stormflow from single, discrete 

storms at station CR02. Because 3 to 5 days typically 

pass between the time of precipitation and peak 

streamflow, and 10 to 14 days typically pass before 

streamflow returns to near base-flow conditions at 

station CR02, it was difficult to collect samples through 

a full Stormflow period before another Stormflow 

period began. Consequently, sample collection at 

station CR02 generally was not able to fully 

characterize the organic content of the stream water 

throughout a discrete Stormflow period. During an 

extended dry period, however, the time before, during, 

and after a complete Stormflow period was sampled 

from July 16-September 17,1997 (hereafter referred to 

as the 1997 summer storm). The 1997 summer storm 

resulted primarily from a single precipitation period on 

July 21, 1997.

Daily streamflow averaged from 7.4 to 10 ft3/s 

before the Stormflow period and increased to a peak 

daily flow of 338 ft3/s on July 26, 1997 (White and 

others, 1998) (fig. 14). Streamflow returned to near

32 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
Table 7. Timing of peak in light absorbance at 253.7 nanometers (UV254) and concentrations of dissolved organic 

carbon (DOC), trihalomethane formation potential (THMFP), total organic halide formation potential (TOXFP), and 

haloacetic acid formation potential (HAAFP) in relation to peak streamflow at selected stations during selected 

stormflow periods, Chickahominy River Basin, Virginia

[cm" 1 , per centimeter; mg/L, milligrams per liter; pig/1, micrograms per liter; |0,g/l as Cl, micrograms per liter as chloride; IS, insufficient sample 

distribution to determine; =, at the time of peak flow; +, after peak streamflow; -, before peak streamflow]

Determination

Station number

CR87 WOS55 SCT01 CR02 DCR03

August 1-6, 1996

UV254(cm-')

DOC (mg/L)

THMFP (^tg/L)

TOXFP (u.g/L as Cl)

HAAFP (M.g/L)

IS + +

IS +

IS +

IS + +

IS IS IS

= +

+ IS

IS

IS

+ IS

September 6-1 6, 1996

UV254(cm-') IS + - + IS

October 8-1 7, 1996

UV254 (cm"')

DOC (mg/L)

THMFP ftig/L)

= = +

IS =

IS +

= +

= +

= +

March 13-16, 1997

UV254(cm-') - - IS

July 17 through September 17, 1997

UV254(cm-') + IS + IS

November 7-20, 1997

UV254(cm-')

DOC (mg/L)

THMFP (jig/L)

+ + -

IS IS

IS IS

IS

IS IS

IS IS

February 16 through March 13, 1998

UV254(cm-')

DOC (mg/L)

THMFP (n,g/L)

TOXFP (ng/L as Cl)

IS IS IS

IS IS IS

IS IS IS

IS IS IS

+ +

+ IS

+ IS

+ IS

Dissolved Organic Carbon and Disinfection By-Product Precursors 33
base-flow conditions about August 4, 1997, and 

decreased to record low flows (0.06 ft3/s) by September 

4, 1997 (White and others, 1998).

UV254 responded to changing streamflow at 

station CR02 (fig. 14). In three samples collected 

before the stormflow period and in the first sample 

collected during the stormflow period, UV254 ranged 

from 0.311 to 0.316 cm" 1 . As streamflow initially 

increased, UV254 decreased to 0.201 cm' 1 on July 23, 

1997, and returned to near pre-storm values at about 

the time of peak flow. UV254 peaked at 0.551 cm' 1 on 

August 4, 1997, 14 days after precipitation and 9 days 

after peak flow. The increase in UV254 was about 75 

percent above pre-storm levels and 175 percent above 

the low value early in the stormflow period. UV254 

then gradually declined through September 17, 1997, 

to a low of 0.245 cm' 1 .

Changes in 18O and D reflected the hydrologic 

response of the system during this stormflow period 

(fig. 15A). The composition of 18O and D before and 

during the early part of the stormflow period indicates 

that stream water was affected by evaporation as 

streamflow increased from 7.7 to 55 ft3/s. The isotopic 

composition then shifted to approximately that of

global meteoric water as streamflow increased to a 

peak of 314 ft3/s, and then slowly decreased to 

25.2 ft3/s. This shift reflected the presence of water that 

likely originated from recent precipitation and was 

transported through either surface runoff, interflow, or 

shallow ground-water flow. At the end of the samplecollection period (September 17), the isotopic 

composition of the stream water again reflected the 

effects of evaporation.

Changes in UV254 during this stormflow period 

can be explained by the hydrologic response inferred 

from the isotopic composition of the stream water. 

UV254 was stable early in the stormflow period when 

the stable isotopes were of uniform composition and 

reflected evaporation. The increased streamflow during 

this period probably reflects the flushing of water that 

had been in the basin prior to the storm. The decreases 

in UV254 occurred coincident with the isotopic shift 

toward that of meteoric water and probably resulted 

from dilution of the stream water by direct 

precipitation on the stream and by surface runoff from 

the watershed. The isotopic composition of the stream 

water (sample 4) at the time of the lowest UV254 (July 

23) was that of meteoric water. As UV254 increased

co DC

LLJ 

LLJ

< cc 

z Lu

co «^ in ^

CM =

< LU 

LLI O

OD:

-r

DC ?

O

CO

CD

<

Io

0.6

0.5

0.4

0.3

0.2

0.1

0 

7/14/97 7/21/97 7/28/97 8/4/97 8/11/97

1,000

100

10

0.1

8/18/97 

DATE

8/25/97 9/1/97

0.01 

9/8/97 9/15/97 9/22/97

O 

O

DC 

LLI 

Q_

LLI 

LLI 

LL

O 

CO

ID 

O

LLI 

DC

fe

Figure 14. Changes in streamflow (Q) and light absorbance at 253.7 nanometers (UV254) during the 1997 summer storm at 

station CR02, Chickahominy River Basin, Virginia.

34 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
CC 

LU 

Q.

? -10

=>

CC 

LUILLJ 

Q

LU 

Q

-20

-30

Chickahominy River Basin Meteoric Water Line

(A)

STREAMFLOW

SAMPLE (CUBIC FEET 

NUMBER DATE PER SECOND)

7/16/97

7/18/97

7/21/97

7/23/97

7/27/97

8/4/97

9/17/97

7.7

17

55

222

314

25.2

0.06

Chickahominy River Basin Evaporation Line

-5 -4 -3 -2 -1 

DELTA OXYGEN-18, IN PER MIL

cc

LLJ 

CL

-10

-20

CC

W -30

ID 

LU 

Q

LU 

Q

-40

-50 -

-60

Chickahominy River Basin 

Meteoric Water Line

Chickahominy River Basin 

Evaporation Line

/ Global Meteoric Water Line

J_____I

* 1997 SUMMER STORM 

O 1998 WINTER STORM

I_____I_____I_____

-9 -8 -7 -6 -5 -4 -3 -2 

DELTA OXYGEN-18, IN PER MIL

-1

Figure 15. Relation of oxygen-18 and deuterium for the 1997 summer storm (A) 

and relation of oxygen-18 and deuterium for the 1997 summer and 1998 winter 

storms (B) at station CR02, Chickahominy River Basin, Virginia.

Dissolved Organic Carbon and Disinfection By-Product Precursors 35
toward the end of the stormflow period, the isotopic 

composition of the stream water remained that of 

meteoric water, indicating the continued effects of 

recent precipitation. After the stormflow period ended, 

the isotopic composition of the stream water again 

reflected evaporation at the end of the samplecollection period.

The peak in UV254 after the peak in streamflow, 

as the stream began to return to base-flow conditions, 

likely resulted from the discharge of DOC transported 

through interflow and shallow ground water. Water 

flowing along these transport pathways has a longer 

traveltime than surface runoff and comprises a larger 

part of the streamflow as stormflows decrease. These 

transport pathways also have a greater likelihood of 

encountering soluble organic material as the water 

infiltrates through surface leaf litter and the shallow 

soil zone.

The February 16-March 13, 1998 samplecollection period (hereafter referred to as the 1998 

winter storm) was a time of periodic precipitation and 

storm-water runoff. As such, samples collected in this 

period show the effects of one precipitation period 

superimposed on the effects of antecedent precipitation 

periods.

Streamflow at station CR02 in February 1998 

averaged 1,198 ft3/s, 2.8 times the long-term monthly 

average of 430 ft3/s, and in March 1998 averaged 

1,055 ft3/s, about 2.2 times the long-term monthly 

average of 481 ft3/s (table 3). Streamflow increased 

from 429 ft3/s when the first sample was collected to a 

first peak of 1,330 ft3/s on February 21, 1998, 

following precipitation on February 16-17; streamflow 

declined to 878 ft3/s on February 26, then increased to 

950 ft3/s on February 27, 1998 (fig. 16A) following 

additional precipitation on February 22. Streamflow 

then declined to a low of 353 ft3/s on March 6 before 

increasing to 1,590 ft3/s on March 13, 1998, after 

precipitation on March 6. Sample collection ended 

March 13.

UV254 generally responded in a manner similar 

to its response in other storms, increasing from 

0.242 cm' 1 on February 16 to 0.371 cm' 1 on February 

23 (an increase of approximately 53 percent), two days 

after the first peak in streamflow (table 8; fig. 16A). 

UV254 declined to 0.280 cm' 1 on February 27, the day 

before the small second peak in flow and again peaked 

at 0.345 cm' 1 on March 4, four days after the second 

peak in streamflow. Concentrations of DOC, THMFP, 

and TOXFP responded similarly to UV254: the

concentration of DOC peaked three days after the first 

peak in streamflow (fig. 16B), THMFP concentrations 

peaked two to three days after the first peak in 

streamflow (fig. 16C), and TOXFP concentrations 

peaked the day after the first peak in streamflow (fig. 

16D). DOC and THMFP concentrations increased 

about 50 percent, TOXFP concentrations increased by 

more than 75 percent, and HAAFP concentrations 

increased less than 25 percent from antecedent to peak 

conditions. The isotopic composition of the stream 

water changed little during the 1998 winter storm as 

evaporation rates are low this time of year and the 

isotopic composition of stream water was similar to 

that of meteoric water for the Chickahominy River 

Basin (fig. 15B).

Although the antecedent hydrologic conditions 

were very different between the summer and winter 

storms, the responses of UV254 to increasing 

streamflow were similar. Of the seven storm periods 

sampled at station CR02 during the course of the study, 

the peak in UV254 lagged the peak in streamflow three 

times, occurred approximately at the peak in 

streamflow three times, and preceded the peak in flow 

once. In all cases, increasing streamflow resulted in 

increased concentrations of DOC, THMFP, TOXFP, 

and HAAFP compared to antecedent conditions.

IMPLICATIONS FOR PUBLIC SUPPLY

Results of this study have implications for the 

timing of withdrawal of water for public supply at 

Walkers Dam and for water treatment, as well as for the 

use of other rivers for public water supply. The City of 

Newport News withdraws water from the 

Chickahominy River at Walkers Dam because it is the 

closest point on the river to the water treatment plant 

that is not substantially affected by saltwater. This 

location is fortuitous because of the downstream 

decrease in concentrations of DOC and DBP 

precursors. Concentrations of DOC and DBP 

precursors at CR02, the closest sampling point to 

Walkers Dam, were among the lowest measured in the 

nontidal part of the Chickahominy River. The 

downstream decrease in the organic content of stream 

water observed in the Chickahominy River likely will 

be observed in other streams that have similar channel 

and flow characteristics. Therefore, locating 

withdrawal points in the lower part of basins, so long as 

other problems such as saltwater intrusion are not

36 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
o OJ "^ ^ 3 3 

IT J2.CQ ^ CD

I g | gcjT

CD 05 G> ~_* O1 O

~> 3 - » 13 -^ 3

03-0 S ifXo

^?|^^S

-D' - s

TOTAL ORGANIC HALIDE

FORMATION POTENTIAL, IN

MICROGRAMS PER LITER

AS CHLORIDE

Ul

o 

o o

N> NJ CO 

O Ul O 

O O O 

000

-D

CD

.

03^ 

03 0-~t 03 .

o 3-

. 0) 

CQ

o o

m

co O CD^^

00 tt

Q.

01

CO

2/15/98 r r

2/22/98

3/1/98

3/8/98

3/15/98

Ul -1

§ 8o

TRIHALOMETHANE

FORMATION POTENTIAL, IN

MICROGRAMS PER LITER

DISSOLVED ORGANIC

CARBON, IN MILLIGRAMS

PER LITER

CJ1 

O 

O

Ul

o 

o

STREAMFLOW, IN CUBIC FEET PER SECOND

 o

T3
Table 8. Stage, light absorbance at 253.7 nanometers (UV254), and concentrations of dissolved organic carbon 

(DOC), trihalomethane formation potential (THMFP), total organic halide formation potential (TOXFP), and 

haloacetic acid formation potential (HAAFP) at initial, peak, and after peak ("After") flow of selected stormflow 

periods at stations CR87, WOS55, and CR02, Chickahominy River Basin, Virginia

[cm, centimeter; -, no data; mg/L, milligrams per liter; p.g/L, micrograms per liter; Cl, chloride]

Station number

Determination CR87 WOS55

Initial Peak After Initial Peak After Initial

CR02

Peak After

August 1-6, 1996

Stage (feet)

UV254 (per cm)

DOC (mg/L)

THMFP Qig/L)

TOXFP Qigfl, as Cl)

HAAFP Qig/L)

- - - 2.41 3.24

- - - 0.625 0.679

 13 17

630 1,300

- - - 4,400 4,900

- - - 600 600

2.78

0.679

17

1,300

4,900

600

4.15

0.437

11

760

2,800

520

5.75

0.571

14

940

3,200

640

5.25

0.547

14

930

2,600

640

September 6-1 6, 1 996

Stage (feet)

UV254 (per cm)

2.12 3.25

- - - .394 .615

2.59

.615

2.99

.376

8.81

.734

7.45

.734

October 8-1 7, 1996

Stage (feet)

UV254 (per cm)

DOC (mg/L)

THMFP (ug/L) -

3.47 6.12 2.03 2.86 4.29

.197 .415 .335 .333 .758

6.1 9.9 9.6 9.8 14

380 620 610 640 1,000

2.01

.541

14

1,000

5.55

.325

7.8

520

8.77

.411

11

710

6.65

.340

8.5

570

March 13-16,1997

Stage (feet)

UV254 (per cm)

Stage (feet)

UV254 (per cm)

2.72 4.04 2.87 2.15 2.65

.305 .408 .310 - .304 .487

July 17 through September 17,

1.60 3.05 1.50 . 1.91 1.91

.224 .353 .162 - .298 .432

2.16

.288

1997

1.15

.115

5.96

.280

1.93

.311

6.01

.353

5.66

.551

5.70

.291

1.75

.245

November 7-20, 1997

Stage (feet)

UV254 (per cm)

DOC (mg/L)

THMFP Qig/L)

Stage (feet)

UV254(percm)

DOC (mg/L)

THMFP (jig/L)

TOXFP Qig/L as Cl)

HAAFP (jig/L)

2.35 5.39 2.50 . 2.55 3.41

.143 .442 .266 .325 .478

7.6 12 6.7 13 15

290 710 550 630 810

February 16 through March 13,

- - - - -

- - - - -

_

- - .- - -

- - - - -

- - - - -

2.09

.273

11

670

1998

-

-

-

-

-

-

3.58

.179

8.2

350

6.45

.242

6.6

360

1,600

710

6.83

.309

12

470

8.69

.371

9.9

530

2,900

870

5.26

.197

10

420

6.03

.280

8.4

470

2,400

800

38 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
created, should reduce the cost of removing DOC and 

reduce the formation of DBFs as water is treated for 

public supply.

The observed change in the organic content of 

stream water resulting from stormflow is a 

consideration in timing the withdrawal of raw water. 

During stormflow periods, the organic content of 

stream water was typically lowest in the early part of 

stormflow periods and increased to higher levels at, or 

following, the peak in streamflow. Water having 

relatively low organic content could be withdrawn 

early in stormflow periods, and withdrawal could be 

stopped in the middle to later part of the stormflow 

period to minimize the cost of removing DOC and DBF 

precursors. This strategy would be particularly useful 

when storage in reservoirs is depleted. During 

extremely low base-flow periods, such as that in the 

summer of 1997, the City of Newport News 

Waterworks is not permitted to withdraw water from 

the Chickahominy River because flow cannot be 

reduced to less than 10 ft3/s by withdrawals. When 

streamflow increases because of storm-water runoff, 

the delay in the increase in the organic content of 

stream water would provide an opportunity to

withdraw water and store it in the large reservoirs for 

later use and (or) to pump it to the terminal reservoirs 

for more immediate use. Withdrawal of water could 

resume later in the stormflow period after the organic 

content of the stream water declines to acceptable 

levels.

Concentrations of THMFP and HAAFP 

exceeded the MCLs of 80 and 60 |ig/L for THMs and 

HAAs, respectively, in all samples collected at station 

CR02 and in almost all samples collected at all other 

stations throughout the basin. Because treatment of the 

raw water with alum before chlorination removes 50 to 

75 percent of the THMFP and HAAFP, concentrations 

of THMs and HAAs in treated water average 50 (ig/L 

annually (Michael Hotaling, Newport News 

Waterworks, written commun., 1999). Thus, removal of 

DOC before chlorination of the raw water is essential 

in providing water having concentrations of THMs and 

HAAs less than the MCLs.

The fact that a large part of the TOXFP consists 

of organic halides other than THMs has important 

implications if MCLs for additional organic halides are 

developed. The percentage of THMFP concentrations 

composing TOXFP concentrations varied depending on

oc

LU

Ocr

I- LLJ 

< Q_

UJ

DC

cc

LU

2,000

1,500

1,000

500

100%

1,000 2,000 3,000 4,000 5,000 6,000

TOTAL ORGANIC HALIDE FORMATION POTENTIAL, 

IN MICROGRAMS PER LITER AS CHLORIDE

Figure 17. Percentage of total organic halide formation potential consisting of trihalomethane formation potential in 

samples, Chickahominy River Basin, Virginia.

Implications for Public Supply 39
TOXFP concentrations (fig. 17). Percentages are 

calculated by assuming that the THMs consist entirely 

of chloroform (THMs are largely chloroform) to 

determine how much of the THM concentration is 

chloride. This is necessary because the TOXFP 

concentration is expressed as chloride. At TOXFP 

concentrations less than 1,000 |Ug/L, THMFP 

concentrations composed from 10 to almost 100 

percent of the TOXFP. The maximum THMFP 

concentrations increased proportionally less than the 

TOXFP concentrations as TOXFP concentrations 

increased from 1,000 to 5,000 |ig/L, and the maximum 

percentage of the THMFP composing the TOXFP 

concentrations greater than 1,000 |ig/L approached 25 

percent.

Water suppliers can take advantage of natural 

spatial and temporal variability in the organic content 

of stream water in locating withdrawal points and in 

deciding when to make withdrawals. Raw-water 

withdrawal points can be located along a stream where 

the organic content of the stream water is lowest. By 

using reservoirs to store water temporarily, the water 

supplier can withdraw water when the organic content 

of the water is low. Reservoirs also allow time for 

degradation of the DOC to occur by natural processes.

The specific nature of changes in the organic 

content of water withdrawn from the Chickahominy 

River and stored in the reservoirs is not known. An 

evaluation of these changes using existing and possibly 

newly collected data would be useful in determining 

how to use the reservoirs to reduce the organic content 

of the raw water and, consequently, the cost of treating 

the water. Moreover, storing water in reservoirs has 

potential implications for the effects of the organic 

content on taste and odor, in addition to its effects on 

DBPs.

SUMMARY AND CONCLUSIONS

Surface waters used for public supply are 

commonly disinfected with chlorine to help assure 

potability. When chlorinated water contains dissolved 

organic carbon (DOC), however, the chlorine and other 

halogens react with the organic carbon to produce a 

variety of halogenated disinfection by-products 

(DBPs). Many of these DBPs are known, or suspected, 

carcinogens that include trihalomethanes (THMs) and 

haloacetic acids (HAAs). Knowledge of how 

concentrations of the precursors and DOC change

spatially and temporally can be used to minimize water 

treatment and pumping costs and to allow for effective 

treatment of the raw water.

The Chickahominy River is used by the City of 

Newport News, Va., as a part of its raw-water supply. 

Because the DOC concentration in the river commonly 

ranges from 6 to 12 mg/L, formation of DBPs is of 

concern.

This report describes results of a study 

conducted by the U.S. Geological Survey, in 

cooperation with the City of Newport News, to evaluate 

spatial and temporal variations in the organic content of 

the Chickahominy River. Field studies evaluated 

variations in the organic content of stream water under 

a range of hydrologic conditions to determine possible 

effects on use of the water for public supply. 

Laboratory studies evaluated (1) the role of stream-bed 

detritus as a source of DOC to stream water and (2) 

degradation processes as a cause of decreasing DOC in 

stream water. The role of ground-water discharge as a 

source of organic carbon was evaluated by analyzing 

the organic content of water from wells and stream-bed 

seeps.

Selected samples were analyzed for 

concentrations of DOC, THM formation potential 

(THMFP), total organic halide formation potential 

(TOXFP), and HAA formation potential (HAAFP). 

Light absorbance at 253.7 nm (UV254) was used as a 

surrogate for these analyses in additional samples to 

provide a more comprehensive representation of the 

natural system than could otherwise be obtained. The 

stable isotopes oxygen-18 and deuterium were 

analyzed in selected samples to help evaluate the 

effects of hydrologic processes on the organic content 

of stream water.

Results indicate that stream-bed detritus can be a 

substantial source of DOC to stream water; UV254 of 

de-ionized water increased from 0.041 to 0.447 cm' 1 

after the first 4 hours of incubation. These values were 

similar to those commonly measured in stream water. 

Results also indicate that degradation of the DOC in 

stream water through photodegradation is an important 

process; the UV254 of samples exposed to sunlight at 

room temperature decreased by as much as 50 percent 

in 83 days.

Ground water can be a substantial source of 

organic carbon to stream water. UV254 of water from 

wells and seeps in alluvial sediments was equal to, or

40 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
greater than, that of streams, ranging from 0.102 to 

2.45 cm' 1 . The DOC content of the seeps and ground 

water ranged from 2.5 to 9.5 mg/L.

During base-flow periods, UV254 and 

concentrations of DOC, THMFP, TOXFP, and HAAFP 

generally decreased downstream along the main stem 

of the Chickahominy River. Decreases of 50 percent or 

more were common. These analytes decreased because 

the input of organic carbon to the stream water was 

exceeded by decreases in the organic carbon. This 

probably occurred because (1) the organic content of 

water in the tributaries in the upper part of the basin 

was lower than, and diluted, the higher organic content 

of water in the main stem of the Chickahominy River; 

(2) during base-flow periods the direct contribution to 

the organic content of the stream water by the organic 

litter in the wetland flood plain was limited; (3) 

traveltimes were long between the headwaters and the 

lower nontidal part of the basin, thus allowing 

substantial time for DOC degradation; and (4) the 

meandering, broad channels and the presence of 

multiple shallow channels in the Coastal Plain part of 

the Chickahominy River enhanced the opportunity for 

degradation.

During stormflow periods, the time of peak 

organic content of stream water was generally at, or 

after, the time of peak streamflow. UV254 and 

concentrations of DOC, THMFP, and TOXFP generally 

increased from 16 to almost 100 percent above prestorm levels during stormflow periods. During a 

stormflow period in the summer of 1997, for example, 

UV254 at the downstream station (CR02) first 

decreased from 0.311 cnr 1 before the storm to 

0.201 cm' 1 early in the storm, then peaked at 0.551 cm' 1 

10 days after the peak in streamflow. UV254 gradually 

declined to a low of 0.245 cm- 1 53 days after the peak 

in streamflow.

Several processes appear to control the organic 

content of stream water during stormflow periods. 

Decreases in UV254 such as those identified early in 

the 1997 summer storm are likely not a common 

occurrence but probably result from dilution by the 

high intensity and short duration of the precipitation 

that produces the stormflows during extremely dry 

periods. UV254 probably peaked after the peak in 

streamflow because organic carbon leached from the 

organic litter through the soil and discharged to the 

streams with interflow and shallow ground water late in 

the stormflow period. Because soluble organic carbon 

was leached from the organic litter layer by infiltrating

precipitation, the amount of soluble organic carbon 

available to surface runoff was limited. The decrease in 

UV254 during and after return to base-flow conditions 

probably resulted from the decrease in the interflow 

and shallow ground-water contribution to streamflow 

and the degradation of organic carbon.

Study results have implications for use of the 

Chickahominy River and similar rivers for public 

supply. The downstream decrease in the organic 

content of stream water observed in the Chickahominy 

River likely will be observed in other streams that have 

broad, meandering channels and sluggish flow 

characteristics. Thus, locating withdrawal points as far 

downstream as possible likely would minimize the 

formation of DBPs. Such decreases probably would not 

occur in rivers that have deep channels and moderately 

flowing water.

Concentrations of THMFP and HAAFP 

exceeded the recently established maximum 

contaminant levels (MCLs) of 80 and 60 |lg/L for 

THMs and HAAs, respectively, in all samples collected 

at the farthest downstream station on the 

Chickahominy River. Because treatment of the raw 

water with alum before chlorination removes 50 to 75 

percent of the THMFP and HAAFP, concentrations of 

THMs and HAAs in treated water average 50 (ig/L 

annually. Consequently, treatment of the raw water 

prior to chlorination helps to reduce the THM and 

HAA concentrations below the MCLs.

The organic content of stream water changes 

during stormflows; while streamflow increases and the 

organic content of the water remains low, water can be 

withdrawn and stored for a variable amount of time in 

the reservoirs. Withdrawal can be discontinued when 

the organic content of the river water exceeds a selected 

level, then resumed after the organic content drops 

below that level. The organic content of water can 

change when the water is stored in reservoirs, and an 

evaluation of these changes would be useful in 

determining how the reservoirs can be used to reduce 

the organic content of the raw water and, consequently, 

the cost of treating the water.

Summary and Conclusions 41
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MacCarthy, Patrick, 1985, Humic substances in soil, 

sediment, and water Geochemistry, isolation, and 

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American Public Health Association, 1995, Standard 

methods for the evaluation of water and wastewater 

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Bencala, K.E., Kennedy, V.C., Zellweger, G.W., Jackman, 

A.P., and Avanzino, R.J., 1984, Interactions of solutes 

and streambed sediment 1. An experimental analysis 

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Constantz, Jim, 1998, Interaction between stream

temperature, streamflow, and groundwater exchanges in 

alpine streams: Water Resources Research, v. 34, no. 7, 

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Coplen, T.B., Wildman, J.D., and Chen, J., 1991, 

Improvements in the gaseous hydrogen-water 

equilibration technique for hydrogen isotope ratio 

analysis: Analytical Chemistry, v. 63, p. 910-912.

Coplen, T.B., 1993, Uses of environmental isotopes, in

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York, Van Nostrand Reinhold, p. 227-253.

Craig, H. 1961, Isotopic variations in meteoric waters: 

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Daniels, P. A., Jr., and Onuschak, Emil, 1974, Geology of the 

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quadrangles, Virginia: Virginia Department of 

Conservation and Economic Development, Division of 

Mineral Resources, Report of Investigations 38, 75 p., 

13 plates.

Edzwald, J.K., Becker, W.C., and Wattier, K.L., 1985,

Surrogate parameters for monitoring organic matter and 

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Findlay, Stuart, 1995, Importance of surface-subsurface 

exchange in stream ecosystems the hyporheic zones: 

Limnology and Oceanography, v. 40, no. 1, p. 159-164.

Fishman, M.J., ed., 1993, Methods of analysis by the U.S. 

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Laboratory determinations of inorganic and organic 

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Focazio, M.J., and Cooper, R.E., 1995, Selected

characteristics of stormflow and base flow affected by 

land use and cover in the Chickahominy River Basin, 

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42 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
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References Cited 43

APPENDIX
Appendix 1 . Streamflow and stage and selected organic analyses of stream-water samples, Chickahominy River 

Basin, Virginia

[-, no data; mg/L, milligrams per liter; (ig/L, micrograms per liter; Cl, chloride]

Station 

number

CR60

CR60

CR60

CR60

CR60

CR60

STR01

STR01

STR01

STROf

STR01

STR01

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

uses

identification number

2042260

2042260

2042260

2042260

2042260

2042260

2042284

2042284

2042284

2042284

2042284

2042284

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

Date

8/21/95

3/14/96

12/9/96

2/11/97

5/29/97

9/16/97

8/21/95

3/11/96

12/9/96

2/11/97

5/29/97

9/16/97

8/23/95

3/11/96

10/8/96

10/9/96

10/9/96

10/10/96

10/12/96

10/14/96

10/17/96

11/13/96

12/11/96

1/14/97

2/11/97

3/13/97

3/14/97

3/14/97

3/15/97

3/15/97

3/16/97

3/17/97

3/18/97

Streamflow 

Time (cubic 

feet per 

second)

900 0.000

930

1330

1050

830

810

1015 .103

1050

1445

1135

915

910

1815

1220

1500

930

1800

1400

1520

1015

1100

945

750

1030

1200

1510

1515

1850

935

1525

1315

1045

940

Stage 

(feet)

-

-

94.00

94.07

93.09

92.92

-

-

95.55

93.68

-

91.65

1.43

2.77

3.47

5.69

6.12

5.53

2.97

2.28

2.03

2.91

4.25

3.19

3.92

2.72

2.93

3.10

3.79

4.04

3.58

3.10

2.87

Light 

absorbanceat 

253.7 

nanometers 

(per 

centimeter)

0.321

.518

.734

.572

.459

.321

.262

.341

.505

.346

.374

.156

.597

.301

.197

.262

.415

.343

.346

.335

.345

.487

.429

.317

.315

.305

.408

.331

.370

.385

.312

.310

.313 ,

Dissolved 

organic 

carbon 

(mg/L)

11

13

20

-

13

-

9.0

8.7

14

-

12

-

17

8.7

6.1

7.6

-

9.9

9.6

-

-

13

11

9.9

-

-

-

-

-

-

-

-

-

Total 

organic 

carbon 

(mg/L)

-

-

20

-

13

-

-

-

14

-

12

-

-

-

7.2

7.7

-

10

10

-

-

13

11

10

-

-

-

-

-

-

-

-

-

Trihalomethane 

formation 

potential

fog/L)

960

1,000

1,300

-

790

-

690

650

800

-

580

-

1,200

690

380

460

-

620

610

-

-

760

710

840

-

-

-

-

-

- -

-

-

-

Total

organic 

halide 

formation 

potential

fog/las Cl)

-

2,300

-

-

-

-

-

1,600

-

-

-

-

-

1,400

-

-

-

-

-

-

-

-

-

1,200

-

-

-

-

-

-

-

-

-

Haloacetic 

acid 

formation 

potential 

(M/L)

-

-

-

-

-

-

-

540

-

-

-

-

-

-

340

-

-

-

-

-

-

-

-

950

-

-

-

-

-

-

-

-

-

46 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
Appendix 1 . Streamflow and stage and selected organic analyses of stream-water samples, Chickahominy River 

Basin, Virginia Continued

[-, no data; mg/L, milligrams per liter; jig/L, micrograms per liter; Cl, chloride]

Station 

number

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

CR87

UPB01

UPB01

UPB01

UPB01

UPB01

UPB01

HSW01

uses

identification number

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042287

2042426

2042426

2042426

2042426

2042426

2042426

2042429

Date

4/14/97

5/29/97

7/16/97

7/16/97

7/16/97

7/17/97

7/17/97

7/18/97

7/21/97

7/22/97

9/10/97

9/11/97

9/16/97

10/22/97

11/7/97

11/7/97

11/8/97

11/8/97

11/9/97

11/9/97

11/10/97

11/12/97

11/13/97

1/14/98

4/16/98

7/8/98

8/23/95

3/11/96

12/11/96

2/11/97

5/29/97

9/16/97

8/21/95

Streamflow 

Time (cubic 

feet per 

second)

1500

945

1010

1700

1950

915

1400

830

1020

830

840

905

945

900

900

1700

915

1415

930

1630

1330

1330

1430

930

700

845

1730

1305

840

1250

1010

1010

1245 .067

Stage 

(feet)

2.91

2.00

1.60

1.66

1.80

3.05

3.04

2.73

1.85

1.79

1.50

1.53

1.62

1.87

2.35

3.82

4.59

4.88

5.39

5.14

4.51

2.50

-

2.48

2.85

1.70

-

-

-

-

-

-

_

Light 

absorbanceat 

253.7 

nanometers 

(per 

centimeter)

.409

.356

.315

.317

.340

.224

.226

.225

.350

.353

.224

.162

.253

.134

.143

.191

.230

.258

.352

.420

.442

.266

.309

.296

.350

.468

.265

.232

.305

.270

.307

.250

.112

Dissolved 

organic 

carbon 

(mg/L)

9.6

9.3

-

-

-

-

-

-

-

-

-

-

-

7.6

9.0

9.2

11

-

12

-

12

6.7

-

11

-

-

8.0

6.7

9.0

-

7.7

-

4.9

Total 

organic 

carbon 

(mg/L)

9.6

9.3

-

-

-

-

-

-

-

-

-

-

-

6.8

7.8

8.9

10

-

13

-

11

10

-

10

9.3

-

-

-

8.7

-

7.8

-

_

Trihalomethane 

formation 

potential

(MIL)

770

560

-

-

-

-

-

-

-

-

-

-

-

200

290

500

580

-

710

-

680

550

-

560

-

-

540

430

500

-

440

-

190

Total

organic 

halide 

formation 

potential

asCI)

1,400

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

1,600

-

2,400

-

2,000

1,000

-

2,200

-

-

-

1,200

-

-

-

-

_

Haloacid 

formation 

potential

-

-

-

-

-

-

-

-

-

-

-

-

-

240

-

-

-

-

1,200

-

820

760

-

940

-

-

-

560

-

-

-

-

_

Appendix 47
Appendix 1 . Streamflow and stage and selected organic analyses of stream-water samples, Chickahominy River 

Basin, Virginia Continued

[-, no data; mg/L, milligrams per liter; (ig/L, micrograms per liter; Cl, chloride]

Station 

number

HSW01

HSW01

HSW01

HSW01

HSW01

BDT01

BDT01

BDT01

BDT01

BDT01

BDT01

BDC01

BDC01

BDC01

BDC01

BDC01

BDC01

PWC01

PWC01

PWC01

PWC01

PWC01

PWC01

BSC01

BSC01

BSC01

BSC01

BSC01

BSC01

CRT01

CRT01

CRT01

CRT01

USGS 

identification number

2042429

2042429

2042429

2042429

2042429

2042432

2042432

2042432

2042432

2042432

2042432

2042433

2042433

2042433

2042433

2042433

2042433

2042437

2042437

2042437

2042437

2042437

2042437

2042438

2042438

2042438

2042438

2042438

2042438

2042439

2042439

2042439

2042439

Date

3/11/96

12/11/96

2/11/97

5/29/97

9/16/97

8/21/95

3/12/96

12/9/96

2/11/97

5/29/97

9/19/97

8/21/95

3/11/96

12/9/96

2/11/97

5/29/97

9/16/97

8/22/95

3/12/96

12/9/96

2/12/97

5/29/97

9/16/97

8/22/95

3/12/96

12/9/96

2/12/97

5/29/97

9/16/97

8/21/95

3/12/96

12/10/96

2/12/97

Streamflow 

Time (cubic 

feet per 

second)

1430

915

1325

1030

1035

1515 .023

845

1600

1420

1050

1130

1415 2.36

1545

1535

1405

1100

1150

830 .798

1015

1630

845

1530

1230

915 .011

1100

1705

915

1510

1250

1645 .552

1415 - '

945

1040

Light 

absorbanceat

Stage 253'7

(feet) na"°- 

v ' meters

(Per 

centimeter)

.077

.102

.078

.079

.084

.143

.043

.072

.047

.038

.033

.142

.141

.111

.105

.100

.125

.226

.135

.179

.104

.170

.154

.387

.172

.231

.129

.309

.213

.096

.090

.247

.100

Dissolved 

organic 

carbon 

(mg/L)

3.6

4.2

-

3.3

-

2.2

1.9

1.6

-

1.4

-

4.2

3.2

5.8

-

-

-

6.6

4.0

5.4

-

5.6

-

11

5.2

6.1

-

7.5

-

3

3

7.0

-

Total 

organic 

carbon 

(mg/L)

-

4.6

-

3.4

-

-

-

1.9

-

1.3

-

-

-

4.1

-

-

-

-

-

5.3

-

5.8

-

-

-

6.0

-

7.9

-

-

-

6.7

-

Trihalomethane 

formation 

potential

feg/L)

110

130

-

100

-

110

140

100

-

130

-

280

160

300

-

-

-

530

290

360

-

410

-

770

380

410

-

580

-

170

170

450

-

Total

organic 

halide 

formation 

potential

asCI)

240

-

-

-

-

-

310

-

-

-

-

-

430

-

-

-

-

-

710

-

-

-

-

-

760

-

-

-

-

-

360

-

-

Haloacid 

formation 

potential

-

-

-

-

-

-

200

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

48 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
Appendix 1. Streamflow and stage and selected organic analyses of stream-water samples, Chickahominy River 

Basin, Virginia Continued

[-, no data; mg/L, milligrams per liter; (ig/L, micrograms per liter; Cl, chloride]

Station 

number

CRT01

CRT01

CR40

CR40

CR40

CR40

CR40

CR40

CR40

CR40

CR40

CR40

CR40

CR40

CRT08

CRT08

CRT08

CRT08

CRT08

CRT08

HGS01

HGS01

HGS01

HGS01

HGS01

HGS01

CR45

CR45

CR45

CR45

CR45

CR45

TCT07

uses

identification number

2042439

2042439

2042440

2042440

2042440

2042440

2042440

2042440

2042440

2042440

2042440

2042440

2042440

2042440

2042441

2042441

2042441

2042441

2042441

2042441

2042442

2042442

2042442

2042442

2042442

2042442

2042445

2042445

2042445

2042445

2042445

2042445

2042446

Date

5/29/97

9/16/97

11/13/96

12/11/96

1/14/97

2/12/97

4/14/97

5/29/97

7/16/97

9/16/97

10/22/97

1/14/98

4/16/98

7/8/98

8/23/95

3/12/96

12/10/96

2/12/97

5/29/97

9/16/97

8/23/95

3/12/96

12/10/96

2/12/97

5/29/97

9/16/97

8/22/95

3/14/96

12/10/96

2/12/97

5/30/97

9/16/97

8/22/95

Streamflow 

Time (cubic 

feet per 

second)

1410

1420

1100

1015

1200

940

1330

1440

1120

1325

1015

1100

845

920

845 .136

1515

1030

1000

1600

1550

1015 .224

1615

1110

1405

1620

1635

1300 .213

945

1720

1340

930

1705

1410 .014

Stage 

(feet)

-

-

86.04

86.53

85.61

85.81

-

82.50

83.82

84.51

84.88

85.71

85.41

85.35

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

Light 

absorbanceat 

253.7 

nanometers 

(per 

centimeter)

.144

.058

.390

.337

.210

.226

.353

.261

.308

.223

.160

.221

.335

.397

.242

.139

.187

.112

.277

.174

.499

.142

.130

.068

.150

.109

.358

.238

.286

.197

.256

.267

.074

Dissolved 

organic 

carbon 

(mg/L)

3.5

-

12

11

6.9

-

9.2

7.1

-

-

6.9

8.8

-

-

6.0

6.5

4.5

-

7.2

-

8.5

4.6

3.5

-

4.0

-

11

8.2

7.9

-

-

-

2.8

Total 

organic 

carbon 

(mg/L)

3.7

-

12

9.8

7.0

-

9.0

7.1

-

-

7.2

8.5

-

-

-

-

4.9

-

7.3

-

-

-

-

-

3.1

-

-

-

7.7

-

-

-

_

Trihalomethane 

formation 

potential

(M*U

260

-

570

610

510

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

690

310

250

-

-

-

800

460

490

-

-

-

.150

Total

organic 

halide 

formation 

potential

asCI)

-

-

-

-

670

-

-

-

-

-

1,600

1,800

-

-

-

660

-

-

-

-

-

660

-

-

-

-

-

1,000

-

-

-

-

_

Haloacetic 

acid 

formation 

potential

-

-

-

-

710

-

-

-

-

-

920

900

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-.

_

Appendix 49
Appendix 1 . Streamflow and stage and selected organic analyses of stream-water samples, Chickahominy River 

Basin, Virginia Continued

[-, no data; mg/L, milligrams per liter; [igfL, micrograms per liter; Cl, chloride]

Station 

number

TCT07

TCT07

TCT07

TCT07

TCT07

CRT07

CRT07

CRT07

CRT07

CRT07

CRT07

CRT07

CRT07

CRT07

CRT07

CRT07

CRT07

CRT07

CRT07

WOS48

WOS48

WOS48

WOS48

WOS48

WOS48

CNS01

CNS01

CNS01

CNS01

CNS01

CNS01

CNS01

CNS01

USGS 

identification number

2042446

2042446

2042446

2042446

2042446

2042447

2042447

2042447

2042447

2042447

2042447

2042447

2042447

2042447

2042447

2042447

2042447

2042447

2042447

2042448

2042448

2042448

2042448

2042448

2042448

2042454

2042454

2042454

2042454

2042454

2042454

2042454

2042454

Date

3/13/96

12/10/96

2/12/97

5/30/97

9/17/97

8/22/95

3/13/96

11/13/96

12/10/96

1/14/97

2/12/97

4/14/97

5/30/97

7/16/97

9/17/97

10/22/97

1/14/98

4/16/98

7/6/98

8/22/95

3/12/96

12/10/96

2/12/97

5/29/97

9/16/97

8/22/95

3/14/96

11/14/96

12/10/96

1/13/97

2/12/97

4/14/97

5/30/97

Streamflow 

Time (cubic 

feet per 

second)

1415

1345

1255

845

855

1500 .137

1500

1315

1410

1515

1315

1100

915

1340

920

1400

1415

1230

1345

1100 .147

1300

1150

1105

1655

1450

1600 .132

830

1215

1225

1315

1135

945

815

Light 

absorbanceat

/* *\ nanometers 

(per 

centimeter)

.093

.088

.057

.061

.045

.188

.106

.135

.140

.104

.102

.174

.213

.249

.138

.155

.111

.140

.280

.051

.164

.151

.099

.068

.095

.774

.180

.373

.357

.260

.212

.502

- -

Dissolved 

organic 

carbon 

(mg/L)

2.7

3.0

-

2.0

-

4.7

3.7

4.3

8.0

4.0

-

5.3

5.6

-

-

4.1

4.3

4.2

-

2.9

-

5.3

-

3.0

-

14

6.0

10

11

6.9

-

9.7

11

Total 

organic 

carbon 

(mg/L)

-

3.0

-

2.3

-

-

-

5.0

8.2

3.1

-

5.5

5.7

-

-

4.4

3.8

4.5

-

-

-

5.5

-

3.1

-

-

-

11

9.3

7.8

-

11

12

Trihalomethane 

formation 

potential

<M*U

120

170

-

120

-

400

180

320

330

-

-

500

380

-

-

260

280

-

-

110

-

343

-

140

-

1,100

450

610

680

740

-

1,100

750

Total

organic 

halide 

formation 

potential

fog/las Cl)

410

-

-

-

-

-

660

-

-

550

-

-

-

-

-

1,300

780

-

-

-

3,300

-

-

-

-

-

1,300

-

-

900

-

3,400

-

Haloacetic 

acid 

formation 

potential

260

-

-

-

-

240

230

-

-

390

-

-

-

-

-

440

640

-

-

-

-

-

-

-

-

-

540

-

-

780

-

-

-

50 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
Appendix 1 . Streamflow and stage and selected organic analyses of stream-water samples, Chickahominy River 

Basin, Virginia Continued

[-, no data; mg/L, milligrams per liter; |0.g/L, micrograms per liter; Cl, chloride]

Station 

number

CNS01

CNS01

CNS01

CNS01

CNS01

CNS01

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

USGS 

identification number

2042454

2042454

2042454

2042454

2042454

2042454

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

Date

7/16/97

9/16/97

10/22/97

1/14/98

4/16/98

7/16/98

4/20/95

6/13/95

8/22/95

11/30/95

1/26/96

3/14/96

5/21/96

7/17/96

8/1/96

8/2/96

8/2/96

8/3/96

9/6/96

9/6/96

9/7/96

9/8/96

10/8/96

10/8/96

10/9/96

10/9/96

10/10/96

10/12/96

10/17/96

11/14/96

12/10/96

1/14/97

2/12/97

Streamflow 

Time (cubic 

feet per 

second)

1300

1745

1500

1240

1045

1015

830

830

900

815

900

830

730

800

1515

930

1625

845

615

1520

1355

1255

1345

1920

1030

1700

1200

1330

1020

815

1255

1415

1205

Stage 

(feet)

-

-

-

-

-

-

-

-

1.05

2.02

2.50

2.02

1.82

2.91

2.41

3.10

3.24

2.78

2.12

2.48

3.25

2.59

2.86

3.40

4.01

3.73

4.29

2.89

2.01

2.09

2.96

2.17

2.33

Light 

absorbanceat 

253.7 

nanometers 

(per 

centimeter)

.339

.125

.387

.234

.282

.334

.610

.583

.247

.406

.316

-

.783

.785

.625

.612

.671

.679

.394

.424

.543

.615

.333

.477

.468

.581

.758

.543

.541

.395

.330

.216

.191

Dissolved 

organic 

carbon 

(mg/L)

-

-

9.2

8.0

6.8

-

8.3

7.6

6.3

10

-

6.6

14

15

13

14

14

17

-

-

-

-

9.8

9.3

12

-

14

14

-

9.6

9.3

6.8

_

Total 

organic 

carbon 

(mg/L)

-

-

9.4

9.1

8.1

-

7.8

7.8

6.8

11

8.0

-

17

17

13

-

-

-

-

-

-

-

11

11

12

-

14

14

-

11

9.1

7.2

-

Trihalomethane 

formation 

potential

<«!/L)

-

-

600

600

-

-

1,400

840

740

190

840

-

-

-

630

1,100

1,200

1,300

-

-

-

-

640

500

710

-

800

1,000

-

610

620

570

_

Total

organic 

halide 

formation 

potential

fog/las Cl)

-

-

3,500

2,300

-

-

-

-

-

-

-

1,700

-

-

-

4,400

4,400

4,900

-

-

-

-

-

-

-

-

-

-

-

-

-

680

-

Haloacetic 

acid 

formation 

potential

-

-

-

1,300

-

-

820

970

670

410

970

430

-

-

600

590

580

600

-

-

-

-

-

-

-

-

-

-

-

-

-

790

-
Appendix 1. Streamflow and stage and selected organic analyses of stream-water samples, Chickahominy River 

Basin, Virginia Continued

[-, no data; mg/L, milligrams per liter; JJ,g/L, micrograms per liter; Cl, chloride]

Station 

number

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55

WOS55.

WOS55

WOS55

CRS01

CRS01

CRS01

CRS01

CRS01

USGS 

identification number

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042455

2042460

2042460

2042460

2042460

2042460

Date

3/13/97

3/14/97

3/14/97

3/15/97

3/15/97

3/16/97

3/17/97

3/18/97

4/16/97

5/29/97

7/16/97

7/17/97

7/17/97

9/9/97

9/10/97

9/11/97

9/16/97

10/22/97

11/7/97

11/7/97

11/8/97

11/8/97

11/9/97

11/10/97

11/12/97

1/15/98

4/16/98

7/16/98

8/22/95

3/13/96

12/10/96

2/12/97

5/30/97

Streamflow 

Time (cubic 

feet per 

second)

1600

1340

1800

1030

1415

1425

1200

1030

730

1720

1750

715

1015

745

1000

1000

1815

745

1015

1550

1030

1510

1100

1445

1500

830

745

745

1730 .016

1315

1650

1445 . -

815

Stage 

(feet)

2.15

2.27

2.37

2.65

2.65

2.34

2.21

2.16

1.94

1.69

1.91

1.91

1.83

1.18

1.15

1.21

1.15

1.85

2.55

3.10

3.41

3.21

2.88

2.76

2.09

1.14

2.08

1.44

-

-

-

-

_

Light 

absorbanceat 

253.7 

nanometers 

(per 

centimeter)

.304

.478

.487

.327

.436

.309

.288

.343

.591

.384

.298

.432

.317

.124

.122

.165

.115

.231

.325

.363

.418

.478

.358

.317

.273

.257

.439

.330

.308

.151

.127

.113

.481

Dissolved 

organic 

carbon 

(mg/L)

-

-

-

-

-

-

-

-

11

11

-

-

-

-

-

-

-

9.2

13

15

15

-

13

12

11

8.0

10

-

9.3

4.9

4.1

-

-

Total 

organic 

carbon 

(mg/L)

-

-

-

-

-

-

-

-

11

12

-

-

-

-

-

-

-

9.4

13

15

16

-

13

12

11

8.7

9.8

-

-

-

4.1

- .

-

Trihalomethane 

formation 

potential

<«I/L)

-

-

-

-

-

-

-

-

1,100

730

-

-

-

-

-

-

-

360

630

810

670

-

730

720

710

410

-

' -

620

310

240

-

-

Total

organic 

halide 

formation 

potential

asCI)

-

-

-

-

-

-

-

-

4,400

-

-

-

-

-

-

-

-

1,900

2,000

-

2,100

-

2,400

-

-

1,600

-

-

-

690

-

-

-

Haloacetic 

acid 

formation 

potential

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

1,100

-

-

-

-

1,200

-

-

610

-

-

-

-

-

-

-

52 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
Appendix 1. Streamflow and stage and selected organic analyses of stream-water samples, Chickahominy River 

Basin, Virginia Continued

[-, no data; mg/L, milligrams per liter; |o.g/L, micrograms per liter; Cl, chloride]

Station 

number

CRS01

CR70

CR70

CR70

CR70

CR70

CR70

CR70

CR70

CR70

CR70

CR70

CR70

CR70

CR70

CRT06

CRT06

CRT06

CRT06

CRT06

CRT06

TRT06

TRT06

TRT06

TRT06

TRT06

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

USGS 

identification number

2042460

2042470

2042470

2042470

2042470

2042470

2042470

2042470

2042470

2042470

2042470

2042470

2042470

2042470

2042470

2042475

2042475

2042475

2042475

2042475

2042475

2042476

2042476

2042476

2042476

2042476

2042478

2042478

2042478

2042478

2042478

2042478

2042478

Date

9/17/97

8/23/95

3/14/96

11/13/96

12/11/96

1/14/97

2/12/97

4/14/97

5/30/97

7/16/97

9/17/97

10/22/97

1/14/98

4/16/98

7/6/98

8/23/95

3/13/96

12/10/96

2/12/97

5/30/97

9/17/97

3/13/96

12/10/96

2/12/97

5/30/97

9/17/97

4/20/95

6/13/95

11/30/95

1/25/96

3/14/96

5/21/96

7/17/96

Streamflow 

Time (cubic 

feet per 

second)

1010

1430

1215

1400

1115

1645

1515

1200

1020

1500

1100

1130

1530

1330

1500

1400 .023

1100

1625

1600

1100

1210

1215

1600

1540

11210

1140

1130

1000

1000

1215

1015

930

930

Light 

absorbanceat

Stage ££

(per 

centimeter)

.140

.318

.238

.379

.268

.199

.162

.328

.307

.310

.265

.188

.230

.345

.480

.091

.076

.082

.070

.090

.050

.073

.096

.059

.131

.079

.391

1 .070

1 .22 .229

1 .28 .243

1.14

0.98 .436

1.02 .515

Dissolved 

organic 

carbon 

(mg/L)

-

9.9

7.9

12

8.4

6.6

-

8.6

6.9

-

-

8.0

8.8

9.2

-

2.5

2.5

2.9

-

-

-

3.0

3.1

-

4.3

-

7.3

16

9.6

-

5.7

12

10

Total 

organic 

carbon 

(mg/L)

-

-

-

11

7.6

6.6

-

8.6

7.0

-

-

8.3

8.7

9.3

-

-

-

2.8

-

-

-

-

2.9

-

4.5

-

7.9

21

10

8.0

-

12

_

Trihalomethane 

formation 

potential

(H9/L)

-

750

500

600

510

-

-

-

-

-

-

-

-

-

-

42

65

185

-

-

-

150

180

-

240

-

1,000

1,200

600

-

350

-

_

Total

organic 

halide 

formation 

potential

(MS/L 

asCI)

-

-

1,100

-

-

750

-

-

-

-

-

1,800

2,000

-

-

-

720

-

-

-

-

520

-

-

-

-

-

-

-

-

1,200

-

_

Haloacetic 

acid 

formation 

potential

-

-

-

-

-

700

-

-

-

-

-

1,100

700

-

-

-

170

-

-

-

-

150

-

-

-

-

1,000

1,800

400

-

420

-

_

Appendix 53
Appendix 1. Streamflow and stage and selected organic analyses of stream-water samples, Chickahominy River 

Basin, Virginia Continued

[-, no data; mg/L, milligrams per liter; (J-g/L, micrograms per liter; Cl, chloride]

Station 

number

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

USGS 

identification number

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

Date

8/1/96

8/1/96

8/1/96

8/1/96

8/2/96

8/3/96

9/5/96

9/6/96

9/6/96

9/6/96

9/8/96

10/8/96

10/8/96

10/8/96

10/9/96

10/9/96

10/10/96

10/12/96

10/14/96

10/17/96

11/14/96

12/10/96

1/15/97

2/12/97

3/13/97

3/14/97

3/14/97

3/14/97

3/14/97

3/14/97

3/14/97

3/14/97

3/14/97

Streamflow 

Time (cubic 

feet per 

second)

1030

1415

1612

1700

1040

945

1500

710

1015

1620

1140

1000

1230

1610

1145

1630

1120

1215

915

950

945

1530

1145

1635

1705

1100

1225

1235

1255

1455

1655

1855

2055

Stage 

(feet)

1.12

1.16

1.36

1.36

1.05

0.98

0.84

1.68

1.73

1.27

0.90

2.58

3.54

3.58

1.32

1.25

1.42

0.98

0.90

0.83

0.87

1.22

1.04

1.03

1.05

1.23

1.29

1.29

1.30

1.31

-

1.35

1.33

Light 

absorbanceat 

253.7 

nanometers 

(per 

centimeter)

.443

.521

.418

.503

.698

.560

.401

.430

.415

, .402

.355

.407

.410

.462

.465

.483

.453

.356

.345

.455

.297

.188

.186

.148

.174

-

.277

.241

.292

.316

.306

.305

.288

Dissolved 

organic 

carbon 

(mg/L)

12

-

11

14

13

13

-

-

-

-

-

11

11

11

10

-

-

15

7.8

-

7.8

6.0

5.4

-

-

-

-

-

-

-

-

-

-

TrihaloTotal methor- ane 

ganic formacarbon tion 

(mg/L) potential

(W/L)

13 1,100

-

920

1,100

830

880

-

-

-

-

-

12 660

12 750

12 650

11 620

-

-

9.8 660

-

-

8.1 470

6.2 440

5.6 340

-

-

-

-

-

-

-

-

-

- -

Total

or- .. , Halogame hand. aM?'c

for- acid 

ma- formation "f" poten- P°te,n- tial 

tial

asCI)

580

-

2,800

-

3,100 570

3,400 580

-

-

-

-

-

570

-

1 ,200

. -

-

-

-

-

-

-

-

1,100 560

-

-

-

-

-

-

-

-

-

- -

54 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
Appendix 1. Streamflow and stage and selected organic analyses of stream-water samples, Chickahominy River 

Basin, Virginia Continued

 , no data; mg/L, milligrams per liter; |J.g/L, micrograms per liter; Cl, chloride]

Station 

number

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

uses

identification number

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

Date

3/14/97

3/15/97

3/15/97

3/15/97

3/16/97

4/16/97

5/30/97

6/18/97

7/16/97

7/17/97

7/17/97

7/18/97

7/22/97

7/22/97

7/22/97

7/22/97

7/22/97

7/22/97

7/22/97

7/23/97

7/24/97

7/24/97

7/24/97

7/24/97

7/24/97

7/24/97

7/25/97

8/6/97

10/22/97

11/7/97

11/7/97

11/7/97

11/7/97

Streamflow 

Time (cubic 

feet per 

second)

2255

55

255

1140

1610

900

1145

1300

1845

830

1100

950

1524

1554

1754

1814

1909

2109

2309

1500

903

1103

1303

1503

1703

1903

1515

1830

930

800

825

955

1055

Stage 

(feet)

1.29

1.27

1.25

1.17

-

0.93

0.85

-

0.68

0.66

0.64

0.65

-

-

-

-

-

-

-

0.90

-

-

-

-

-

-

0.91

-

0.74

0.99

1.20

1.35

1.49

Light Triabsor- halobanceat . . Total meth- solved 253.7 or- ane

nano- . ganic forma- ganic . meters . carbon tion 

. carbon . .

(per (mg/L) (mg/L) potencenti- { ® ' tial

meter) (l^g/L)

.283 -

.248 -

.285

.232 -

.210 -

.220 7.1 8.9 520

.329 7.6 8.1 470

.535 -

.357 - -

.523 -

.500 -

.455 -

.317 _ _ _

.320 -

.400 -

.402 -

.307 -

.450 -

.365 -

.511

.439 -

.474 -

.503 -

.486 -

.512 -

.492 -

.438 -

.452 -

.449 15 15 400

.364 14 14 680

.373 - -

.449 - - -

.388 14 15 760

Total

organic 

halide 

formation 

potential

asCI)

-

-

-

-

-

2,100

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

1,800

2,200

-

-

_

Haloacetic 

acid 

formation 

potential

-

-

-

' -

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

700

-

-

-

_

Appendix 55
Appendix 1 . Streamflow and stage and selected organic analyses of stream-water samples, Chickahominy River 

Basin, Virginia Continued

[-, no data; mg/L, milligrams per liter; |J,g/L, micrograms per liter; Cl, chloride]

Station 

number

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SCT01

SNC01

SNC01

SNC01

SNC01

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

USGS 

identification number

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042478

2042480

2042480

2042480

2042480

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

Date

11/7/97

11/7/97

11/7/97

11/7/97

11/7/97

11/7/97

11/7/97

11/8/97

11/8/97

11/8/97

11/9/97

11/10/97

1/15/98

4/16/98

7/16/98

3/13/96

12/10/96

2/12/97

5/30/97

4/19/95

6/12/95

8/21/95

11/29/95

12/11/95

1/24/96

2/13/96

3/13/96

5/22/96

6/24/96

7/17/96

8/1/96

8/2/96

8/3/96

Time

1155

1230

1425

1612

1812

2012

2212

12

212

1645

1315

1630

950

930

900

845

1510

1620

1230

1330

1245

1230

1245

905

1200

850

1300

1200

905

1245

1335

1125

1005

Streamflow 

(cubic 

feet per 

second)

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

133

72

2.1

87

130

1,420

935

256

195

26

321

161

242

272

Stage 

(feet)

1.70

1.91

1.89

-

-

-

-

-

-

0.99

1.13

0.91

1.01

.85

0.62

-

-

-

-

3.99

3.10

1.80

3.32

3.95

8.78

8.05

5.00

4.74

2.28

5.72

4.15

5.02

5.32

Light 

absorbanceat 

253.7 

nanometers 

(per 

centimeter)

.387

.385

.347

.370

.359

.357

.346

.347

.338

.346

.331

.291

.353

.222

.410

.204

.195

.124

.239

.385

.462

.261

.283

-

.352

-

.204

.616

-

.448

.473

.466

.494

Dissolved 

organic 

carbon 

(mg/L)

-

-

15

-

-

-

-

-

-

-

-

12.

9.4

8.1

-

6.2

6.4

-

7.3

8.1

9.2

7.8

9.1

-

-

-

8.3

13

-

10

11

10

11

Total 

organic 

carbon 

(mg/L)

-

-

14

-

-

-

-

-

-

-

-

12

9.7

7.6

-

-

6.2

-

7.5

8.3

9.3

-

9.3

9.2

8.7

6.6

-

13

12

10

10

-

-

Trihalomethane 

formation 

potential

<rau

-

-

760

-

-

-

.

-

-

-

-

590

570

-

-

450

410

-

500

1,100

720

720

1,100

660

-

430

540

-

770

-

760

800

760

Total

organic 

halide 

formation 

potential

asCI)

-

-

2,400

-

-

-

-

-

-

-

-

-

2,200

-

-

1,200

-

-

-

-

-

-

-

-

-

-

1,100

-

-

-

-

2,800

3,000

Haloacetic 

acid 

formation 

potential

-

-

-

-

-

-

-

-

-

-

-

-

940

-,

-

-

-

-

-

500

970

600

390

-

-

-

510

-

-

-

520

560

520

56 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
Appendix 1. Streamflow and stage and selected organic analyses of stream-water samples, Chickahominy River 

Basin, Virginia Continued

 , no data; mg/L, milligrams per liter; (ig/L, micrograms per liter; Cl, chloride]

Station 

number

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

USGS 

identification number

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

Date

8/5/96

8/6/96

9/6/96

9/8/96

9/9/96

9/10/96

9/12/96

9/16/96

9/16/96

10/8/96

10/9/96

10/10/96

10/12/96

10/14/96

10/17/96

11/14/96

12/11/96

1/15/97

2/13/97

3/13/97

3/14/97

3/15/97

3/16/97

3/17/97

3/18/97

4/16/97

5/30/97

7/16/97

7/17/97

7/18/97

7/21/97

7/22/97

7/23/97

Time

1200

1025

1700

1045

945

1130

1005

910

1030

1700

825

1040

1125

835

850

1045

1215

1255

905

1755

1635

1345

1520

912

1210

1015

1245

1130

1150

1030

1130

1100

1215

Streamflow 

(cubic 

feet per 

second)

326

265

78

147

1,450

1,330

1,620

711

704

277

545

874

1,380

902

449

426

1,290

346

428

362

339

345

330

332

315

212

105

7.7

9.1

17

55

74

222

Stage 

(feet)

5.75

5.25

2.99

3.98

8.81

8.70

8.99

7.47

7.45

5.55

6.94

8.05

8.77

8.14

6.65

6.43

8.69

6.03

6.52

6.12

5.96

6.01

5.89

5.90

5.7

4.93

3.62

1.90

1.93

2.12

2.83

3.16

4.96

Light 

absorbanceat 

253.7 

nanometers 

(per 

centimeter)

.571

.547

.376

.374

.361

.418

.512

V

.734

.325

-

-

.411

.340

.335

.435

.279

.195

.171

.280

.344

.353

.278

-

.291

.393

.348

.314

.311

.316

.313

.229

.201

Dissolved 

organic 

carbon 

(mg/L)

13

13

-

-

-

-

-

-

7.8

-

9.3

11

8.5

-

10

8.6

6.7

-

-

-

-

-

-

-

9.4

-

-

-

-

-

-

_

Total 

organic 

carbon 

(mg/L)

-

-

-

-

-

-

-

15

-

9.2

11

9.5

10

8.8

-

11

8.7

6.5

-

-

-

-

-

7.5

-

9.6

-

-

-

-

-

-

_

Trihalomethane 

formation 

potential

feg/U

940

930

-

-

-

- .

- -

1,100

-

520

690

530

710

570

-

610

540

440

-

-

-

-

-

530

-

670

-

-

-

-

-

-

_

Total

organic 

halide 

formation 

potential

asCI)

3,200

2,600

-

-

-

-

-

-

-

-

-

-

-

-

-

-

. -

890

-

-

-

-

-

-

-

2,300

-

-

-

-

-

-

_

Haloacetic 

acid 

formation 

potential

540

660

-

-

-

-

-

-

-

900

-

-

920

-

"

-

-

680

-

-

-

-

-

-

-

-

-

-

-

-

-

-

_

Appendix 57
Appendix 1. Streamflow and stage and selected organic analyses of stream-water samples, Chickahominy River 

Basin, Virginia Continued

[-, no data; mg/L, milligrams per liter; |0.g/L, micrograms per liter; Cl, chloride]

Station 

number

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

USGS 

identification number

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

Date

7/24/97

7/25/97

7/28/97

7/29/97

8/1/97

8/4/97

8/5/97

8/6/97

8/12/97

8/18/97

8/25/97

9/3/97

9/9/97

9/11/97

9/17/97

10/21/97

11/7/97

11/8/97

11/8/97

11/9/97

11/10/97

11/12/97

11/13/97

11/18/97

11/20/97

1/16/98

2/16/98

2/17/98

2/17/98

2/18/98

2/18/98

2/19/98

2/20/98

Time

900

1330

1115

845

920

1400

1445

1430

945

1055

1330

1130

840

1050

1305

1200

1130

1140

1610

1415

1545

1550

1315

1330

1345

1115

1520

1140

1715

1115

1515

1515

1100

Streamflow 

(cubic 

feet per 

second)

189

314

293

268

212

26

22

21

10

5.2

1'3

.32

.10

.10

.06

50

105

253

-

413

-

520

-

262

-

340

429

493

-

569

812

1,010

1,040

Stage 

(feet)

4.65

5.66

5.48

5.31

4.85

2.29

2.21

2.18

1.96

1.89

2.02

1.81

1.77

1.77

1.75

2.74

3.58

5.20

5.33

6.32

6.80

6.83

-

5.26

-

6.36

6.45

6.73

7.03

7.03

7.75

8.18

8.25

Light 

absorbanceat 

253.7 

nanometers 

(per 

centimeter)

.276

.300

.411

.469

.527

.551

.507

.478

.376

.355

.351

.275

.266

.283

.245

.210

.179

.244

.293

.309

.298

.249

.259

.231

.197

.284

.242

.252

.256

.246

.273

.285

-

Dissolved 

organic 

carbon 

(mg/L)

-

-

-

-

-

- .

-

-

-

- 

-

-

-

-

-

-

8.2

11

-

12

12

11

-

10

-

9.9

-

6.6

-

7.2

7.6

7.5

7.7

Total 

organic 

carbon 

(mg/L)

-

-

-

-

-

-

-

-

-

9.3

-

-

-

-

-

-

7.6

11

-

13

13

11

-

9.9

-

9.7

-

8.0

-

7.1

8.2

7.4

7.7

Trihalomethane 

formation 

potential

<MU

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

. 350

450

-

470

380

440

-

420

-

490

-

360

-

430

380

370

480

Total

organic 

halide 

formation 

potential

asCI)

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

2,400

2,100

-

-

-

2,000

-

1,800

-

1,800

-

1 ,600

'

1,600

1 ,900

2,200

2,100

Haloacetic 

acid 

formation 

potential

-

-

-

-

-

-

-

660

-

-

-

-

-

-

-

-

-

-

-

-

-

1,000

-

1,000

-

930

-

-

-

710

-

-

800

58 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
Appendix 1. Streamflow and stage and selected organic analyses of stream-water samples, Chickahominy River 

Basin, Virginia Continued

[-, no data; mg/L, milligrams per liter; |J,g/L, micrograms per liter; Cl, chloride]

Station 

number

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

CR02

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

USGS 

identification number

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042500

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

Date

2/21/98

2/22/98

2/23/98

2/24/98

2/25/98

2/26/98

2/27/98

3/2/98

3/4/98

3/6/98

3/9/98

3/10/98

3/11/98

3/12/98

3/13/98

4/16/98

7/16/98

4/20/95

6/13/95

8/22/95

11/30/95

1/14/96

1/25/96

3/14/96

5/21/96

7/17/96

8/1/96

8/2/96

8/3/96

9/6/96

9/6/96

9/7/96

9/8/96

Time

900

910

930

915

930

945

845

1030

1100

930

900

915

945

850

800

1015

1000

1330

1215

1100

1200

850

845

1145

1100

1100

1200

1215

1105

835

1230

1040

915

Streamflow 

(cubic 

feet per 

second)

1,330

1,250

1,010

935

902

878

950

718

449

353

771

1,270

1,350

1,570

1,590

353

237

1.9

10

2.7

4.3

-

8.6

4.9

4.2

12

-

-

-

-

-

-

Stage 

(feet)

8.69

8.59

8.20

8.06

7.98

7.91

8.08

7.50

6.53

6.03

7.62

8.61

8.71

8.93

8.96

6.04

5.93

-

-

-

3.22

3.78

3.30

3.04

3.06

3.67

3.48

3.68

3.44

3.84

3.95

3.93

3.64

Light

absorbanceat 

253.7 

nanometers 

(per 

centimeter)

.296

.324

.371

.357

.320

.314

.280

.325

.345

.300

.309

.327

.386

.326

.360

.450

.388

.246

.837

.345

.204

.305

.189

-

.645

.553

.321

.372

.421

-

.381

.355

.371

Dissolved 

organic 

carbon 

(mg/L)

8.8

9.0

9.4

9.9

8.8

8.7

8.4

9.7

9.3

9.3

-

-

-

-

-

11

-

6.3

8.8

10

6.5

-

-

-

10

13

9.3

-

11

-

-

-

_

Total 

organic 

carbon 

(mg/L)

9.0

9.2

9.5

8.9

8.8

8.7

8.2

9.2

9.4

9.4

-

7.8

-

-

-

11

-

-

8.9

10

6.7

-

6.2

-

11

14

9.9

-

-

-

-

-

_

Trihalomethane 

formation 

potential

(H9/I-)

470

520

530

530

470

520

500

550

530

510

-

150

-

-

-

-

-

950

760

850

470

-

-

-

-

-

760

-

890

-

-

-

_

Total

organic 

halide 

formation 

potential

(H9/L

asCI)

2,500

2,900

2,800

2,600

2,700

2,500

2,400

2,600

2,500

2,600

-

-

-

-

-

-

-

-

-

-

-

-

-

790

-

-

-

-

2,800

-

-

-

_

Haloacetic 

acid 

formation 

potential

(H9/L)

840

-

870

-

790

-

810

960

-

-

-

-

-

-

-

-

-

560

1,200

710

360

-

-

-

-

-

530

-

540

-

-

-

_

Appendix 59
Appendix 1. Streamflow and stage and selected organic analyses of stream-water samples, Chickahominy River 

Basin, Virginia Continued

[-, no data; mg/L, milligrams per liter; |0.g/L, micrograms per liter; Cl, chloride]

Station 

number

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

DCR03

USGS 

identification number

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

2042726

Date

10/8/96

10/8/96

10/9/96

10/9/96

10/12/96

11/14/96

1/15/97

2/13/97

4/16/97

5/30/97

7/17/97

9/10/97

9/10/97

9/17/97

10/22/97

1/15/98

2/16/98

2/17/98

2/17/98

2/17/98

2/18/98

2/18/98

2/18/98

2/19/98

2/20/98

4/16/98

7/16/98

Streamflow 

Time (cubic 

feet per 

second)

1130

1805

930

1315

940

1215

1445

1015

1230

1345

1000 7.8

1130

1335

1635

1100

1120

1645

940

1430

1755

1000

1400

1405

1340

1300

1130

1745

Stage 

(feet)

4.28

6.04

4.24

4.72

3.78

3.82

3.81

3.74

3.66

3.43

3.50

3.63

-

3.66

3.76

3.67

3.66

3.91

4.16

4.38

4.10

4.02

4.02

3.80

3.72

3.64

3.39

Light 

absorbanceat 

253.7 

nanometers 

(per 

centimeter)

.167

.268

.406

.481

.305

' .166

.127

.124

.200

.333

.394

.227

.170

.180

.261

.231

.154

.145

.175

.196

.268

.212

.212

.204

.181

.302

.389

Dissolved 

organic 

carbon 

(mg/L)

5.8

6.9

9.0

8.4

8.5

5.1

4.9

-

6.1

-

-

-

-

-

-

6.6

-

-

-

5.9

6.1

5.8

5.6

5.8

-

7.1

-

Total 

organic 

carbon 

(mg/L)

5.8

7.1

9.1

9.3

8.9

5.6

4.4

-

7.0

-

-

-

-

-

-

6.6

-

-

-

5.5

5.7

5.8

5.6

6.7

-

6.8

-

Trihalomethane 

formation 

potential

(Utt

390

450

550

500

570

370

310

-

510

-

-

-

-

-

-

360

-

-

-

340

320

320

310

350

-

-

-

Total

organic 

halide 

formation 

potential

fog/las Cl)

-

-

-

-

-

-

720

-

2,500

-

-

-

-

-

-

1,300

-

-

-

1,800

1,300

1,500

1,600

1,600

-

-

-

Haloacetic 

acid 

formation 

potential

374

500

-

920

-

-

420

-

-

-

-

-

-

-

-

720

-

-

-

-

-

-

-

-

-

-

-

60 Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River Basin, Virginia
Speiran Dissolved Organic Carbon and Disinfection By-Product Precursors in Waters of the Chickahominy River B

and Implications for Public Supply WRIR 00-4175